Merge branch 's3c-touchscreen-2.6.31' into om-gta01-2.6.31

14 files changed, 2039 insertions, 0 deletions

diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 72e2712c7e2..f8c4dd2226b 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -11,6 +11,68 @@ menuconfig INPUT_TOUCHSCREEN
 
 if INPUT_TOUCHSCREEN
 
+menuconfig TOUCHSCREEN_FILTER
+	boolean "Touchscreen Filtering"
+	depends on INPUT_TOUCHSCREEN
+	select TOUCHSCREEN_FILTER_GROUP
+	select TOUCHSCREEN_FILTER_MEDIAN
+	select TOUCHSCREEN_FILTER_MEAN
+	select TOUCHSCREEN_FILTER_LINEAR
+	help
+	  Select this to include kernel touchscreen filter support.  The filters
+	  can be combined in any order in your machine init and the parameters
+	  for them can also be set there.
+
+config TOUCHSCREEN_FILTER_GROUP
+	bool "Group Touchscreen Filter"
+	depends on INPUT_TOUCHSCREEN && TOUCHSCREEN_FILTER
+	default Y
+	help
+	  Say Y here if you want to use the Group touchscreen filter, it
+	  avoids using atypical samples.
+
+config TOUCHSCREEN_FILTER_MEDIAN
+	bool "Median Average Touchscreen Filter"
+	depends on INPUT_TOUCHSCREEN && TOUCHSCREEN_FILTER
+	default Y
+	help
+	  Say Y here if you want to use the Median touchscreen filter, it's
+	  highly effective if you data is noisy with occasional excursions.
+
+config TOUCHSCREEN_FILTER_MEAN
+	bool "Mean Average Touchscreen Filter"
+	depends on INPUT_TOUCHSCREEN && TOUCHSCREEN_FILTER
+	default Y
+	help
+	  Say Y here if you want to use the Mean touchscreen filter, it
+	  can further improve decent quality data by removing jitter
+
+config TOUCHSCREEN_FILTER_LINEAR
+	bool "Linear Touchscreen Filter"
+	depends on INPUT_TOUCHSCREEN && TOUCHSCREEN_FILTER
+	default Y
+	help
+	  Say Y here if you want to use the Linear touchscreen filter, it
+	  enables the use of calibration data for the touchscreen.
+
+config TOUCHSCREEN_S3C2410
+	tristate "Samsung S3C2410 touchscreen input driver"
+	depends on ARCH_S3C2410 && INPUT && INPUT_TOUCHSCREEN
+	select SERIO
+	help
+	  Say Y here if you have the s3c2410 touchscreen.
+
+	  If unsure, say N.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called s3c2410_ts.
+
+config TOUCHSCREEN_S3C2410_DEBUG
+	boolean "Samsung S3C2410 touchscreen debug messages"
+	depends on TOUCHSCREEN_S3C2410
+	help
+	  Select this if you want debug messages
+
 config TOUCHSCREEN_ADS7846
 	tristate "ADS7846/TSC2046 and ADS7843 based touchscreens"
 	depends on SPI_MASTER
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 3e1c5e0b952..dafec0b5e3f 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -40,3 +40,9 @@ obj-$(CONFIG_TOUCHSCREEN_WM97XX_ATMEL)	+= atmel-wm97xx.o
 obj-$(CONFIG_TOUCHSCREEN_WM97XX_MAINSTONE)	+= mainstone-wm97xx.o
 obj-$(CONFIG_TOUCHSCREEN_WM97XX_ZYLONITE)	+= zylonite-wm97xx.o
 obj-$(CONFIG_TOUCHSCREEN_W90X900)	+= w90p910_ts.o
+obj-$(CONFIG_TOUCHSCREEN_FILTER)	+= ts_filter_chain.o
+obj-$(CONFIG_TOUCHSCREEN_FILTER_GROUP)	+= ts_filter_group.o
+obj-$(CONFIG_TOUCHSCREEN_FILTER_LINEAR)	+= ts_filter_linear.o
+obj-$(CONFIG_TOUCHSCREEN_FILTER_MEDIAN)	+= ts_filter_median.o
+obj-$(CONFIG_TOUCHSCREEN_FILTER_MEAN)	+= ts_filter_mean.o
+obj-$(CONFIG_TOUCHSCREEN_S3C2410)	+= s3c2410_ts.o
diff --git a/drivers/input/touchscreen/s3c2410_ts.c b/drivers/input/touchscreen/s3c2410_ts.c
new file mode 100644
index 00000000000..caccc83cd12
--- /dev/null
+++ b/drivers/input/touchscreen/s3c2410_ts.c
@@ -0,0 +1,552 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (c) 2004 Arnaud Patard <arnaud.patard@rtp-net.org>
+ * iPAQ H1940 touchscreen support
+ *
+ * ChangeLog
+ *
+ * 2004-09-05: Herbert Pötzl <herbert@13thfloor.at>
+ *      - Added clock (de-)allocation code
+ *
+ * 2005-03-06: Arnaud Patard <arnaud.patard@rtp-net.org>
+ *      - h1940_ -> s3c2410 (this driver is now also used on the n30
+ *        machines :P)
+ *      - Debug messages are now enabled with the config option
+ *        TOUCHSCREEN_S3C2410_DEBUG
+ *      - Changed the way the value are read
+ *      - Input subsystem should now work
+ *      - Use ioremap and readl/writel
+ *
+ * 2005-03-23: Arnaud Patard <arnaud.patard@rtp-net.org>
+ *      - Make use of some undocumented features of the touchscreen
+ *        controller
+ *
+ * 2007-05-23: Harald Welte <laforge@openmoko.org>
+ *      - Add proper support for S32440
+ *
+ * 2008-06-23: Andy Green <andy@warmcat.com>
+ *      - Removed averaging system
+ *      - Added generic Touchscreen filter stuff
+ *
+ * 2008-11-27: Nelson Castillo <arhuaco@freaks-unidos.net>
+ *      - Improve interrupt handling
+ *
+ * 2009-04-09: Nelson Castillo <arhuaco@freaks-unidos.net>
+ *      - Use s3c-adc API (Vasily Khoruzhick <anarsoul@gmail.com> provided
+ *        a working example for a simpler version of this driver).
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/input.h>
+#include <linux/init.h>
+#include <linux/serio.h>
+#include <linux/timer.h>
+#include <linux/kfifo.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <asm/irq.h>
+
+#include <mach/regs-gpio.h>
+#include <mach/gpio-nrs.h>
+#include <mach/gpio-fns.h>
+#include <mach/ts.h>
+#include <mach/hardware.h>
+#include <plat/regs-adc.h>
+#include <plat/adc.h>
+
+#include "ts_filter_chain.h"
+
+/* For ts.dev.id.version */
+#define S3C2410TSVERSION	0x0101
+
+#define WAIT4INT(x)		(((x)<<8) | \
+				S3C2410_ADCTSC_YM_SEN | \
+				S3C2410_ADCTSC_YP_SEN | \
+				S3C2410_ADCTSC_XP_SEN | \
+				S3C2410_ADCTSC_XY_PST(3))
+
+#define TSPRINTK(fmt, args...) \
+	printk(KERN_DEBUG "%s: " fmt, __func__ , ## args)
+#ifdef CONFIG_TOUCHSCREEN_S3C2410_DEBUG
+#	define DPRINTK TSPRINTK
+#else
+#	define DPRINTK(fmt, args...)
+#endif
+
+
+MODULE_AUTHOR("Arnaud Patard <arnaud.patard@rtp-net.org>");
+MODULE_DESCRIPTION("s3c2410 touchscreen driver");
+MODULE_LICENSE("GPL");
+
+/*
+ * Definitions & global arrays.
+ */
+
+static char *s3c2410ts_name = "s3c2410 TouchScreen";
+
+#define TS_RELEASE_TIMEOUT (HZ >> 7 ? HZ >> 7 : 1) /* 8ms (5ms if HZ is 200) */
+#define TS_EVENT_FIFO_SIZE (2 << 6) /* Must be a power of 2. */
+
+/*
+ * Per-touchscreen data.
+ */
+
+enum	ts_state {TS_STATE_STANDBY, TS_STATE_PRESSED, TS_STATE_RELEASE_PENDING,
+		  TS_STATE_RELEASE};
+
+struct s3c2410ts {
+	struct input_dev *dev;
+	struct ts_filter_chain *chain;
+	enum ts_state state;
+	int is_down;
+	struct kfifo *event_fifo;
+	struct s3c_adc_client *adc_client;
+	unsigned adc_selected;
+};
+
+static struct s3c2410ts ts;
+
+static void __iomem *base_addr;
+
+/*
+ * A few low level functions.
+ */
+
+static inline void s3c2410_ts_connect(void)
+{
+	s3c2410_gpio_cfgpin(S3C2410_GPG(12), S3C2410_GPG12_XMON);
+	s3c2410_gpio_cfgpin(S3C2410_GPG(13), S3C2410_GPG13_nXPON);
+	s3c2410_gpio_cfgpin(S3C2410_GPG(14), S3C2410_GPG14_YMON);
+	s3c2410_gpio_cfgpin(S3C2410_GPG(15), S3C2410_GPG15_nYPON);
+}
+
+/*
+ * Code that starts ADC conversions.
+ */
+
+static void ts_adc_timer_f(unsigned long data);
+static struct timer_list ts_adc_timer = TIMER_INITIALIZER(ts_adc_timer_f, 0, 0);
+
+static void ts_adc_timer_f(unsigned long data)
+{
+	if (s3c_adc_start(ts.adc_client, 0, 1))
+		mod_timer(&ts_adc_timer, jiffies + 1);
+}
+
+static void s3c2410_ts_start_adc_conversion(void)
+{
+	if (ts.adc_selected)
+		mod_timer(&ts_adc_timer, jiffies + 1);
+	else
+		ts_adc_timer_f(0);
+}
+
+/* Callback for the s3c-adc API. */
+void adc_selected_f(unsigned selected)
+{
+	ts.adc_selected = selected;
+}
+
+/*
+ * Just send the input events.
+ */
+
+enum ts_input_event {IE_DOWN = 0, IE_UP};
+
+static void ts_input_report(int event, int coords[])
+{
+#ifdef CONFIG_TOUCHSCREEN_S3C2410_DEBUG
+	static char *s[] = {"down", "up"};
+	struct timeval tv;
+
+	do_gettimeofday(&tv);
+#endif
+
+	if (event == IE_DOWN) {
+		input_report_abs(ts.dev, ABS_X, coords[0]);
+		input_report_abs(ts.dev, ABS_Y, coords[1]);
+		input_report_key(ts.dev, BTN_TOUCH, 1);
+		input_report_abs(ts.dev, ABS_PRESSURE, 1);
+
+		DPRINTK("T:%06d %6s (X:%03d, Y:%03d)\n",
+			(int)tv.tv_usec, s[event], coords[0], coords[1]);
+	} else {
+		input_report_key(ts.dev, BTN_TOUCH, 0);
+		input_report_abs(ts.dev, ABS_PRESSURE, 0);
+
+		DPRINTK("T:%06d %6s\n",
+			(int)tv.tv_usec, s[event]);
+	}
+
+	input_sync(ts.dev);
+}
+
+/*
+ * Manage the state of the touchscreen.
+ */
+
+static void event_send_timer_f(unsigned long data);
+
+static struct timer_list event_send_timer =
+		TIMER_INITIALIZER(event_send_timer_f, 0, 0);
+
+static void event_send_timer_f(unsigned long data)
+{
+	static int noop_counter;
+	int event_type;
+
+	while (__kfifo_get(ts.event_fifo, (unsigned char *)&event_type,
+			   sizeof(int))) {
+		int buf[2];
+
+		switch (event_type) {
+		case 'D':
+			if (ts.state == TS_STATE_RELEASE_PENDING)
+				/* Ignore short UP event. */
+				ts.state = TS_STATE_PRESSED;
+			break;
+
+		case 'U':
+			ts.state = TS_STATE_RELEASE_PENDING;
+			break;
+
+		case 'P':
+			if (ts.is_down) /* Stylus_action needs a conversion. */
+				s3c2410_ts_start_adc_conversion();
+
+			if (unlikely(__kfifo_get(ts.event_fifo,
+						 (unsigned char *)buf,
+						 sizeof(int) * 2)
+				     != sizeof(int) * 2)) {
+				/* This will only happen if we have a bug. */
+				TSPRINTK("Invalid packet\n");
+				return;
+			}
+
+			ts_input_report(IE_DOWN, buf);
+			ts.state = TS_STATE_PRESSED;
+			break;
+		}
+
+		noop_counter = 0;
+	}
+
+	if (noop_counter++ >= 1) {
+		noop_counter = 0;
+		if (ts.state == TS_STATE_RELEASE_PENDING) {
+			/*
+			 * We delay the UP event for a while to avoid jitter.
+			 * If we get a DOWN event we do not send it.
+			 */
+			ts_input_report(IE_UP, NULL);
+			ts.state = TS_STATE_STANDBY;
+
+			ts_filter_chain_clear(ts.chain);
+		}
+	} else {
+		mod_timer(&event_send_timer, jiffies + TS_RELEASE_TIMEOUT);
+	}
+}
+
+/*
+ * Manage interrupts.
+ */
+
+static irqreturn_t stylus_updown(int irq, void *dev_id)
+{
+	unsigned long data0;
+	unsigned long data1;
+	int event_type;
+
+	data0 = readl(base_addr + S3C2410_ADCDAT0);
+	data1 = readl(base_addr + S3C2410_ADCDAT1);
+
+	ts.is_down = !(data0 & S3C2410_ADCDAT0_UPDOWN) &&
+		     !(data1 & S3C2410_ADCDAT0_UPDOWN);
+
+	event_type = ts.is_down ? 'D' : 'U';
+
+	if (unlikely(__kfifo_put(ts.event_fifo, (unsigned char *)&event_type,
+		     sizeof(int)) != sizeof(int)))
+		/* Only happens if we have a bug. */
+		TSPRINTK("FIFO full\n");
+
+	if (ts.is_down)
+		s3c2410_ts_start_adc_conversion();
+	else
+		writel(WAIT4INT(0), base_addr + S3C2410_ADCTSC);
+
+	mod_timer(&event_send_timer, jiffies + 1);
+
+	return IRQ_HANDLED;
+}
+
+static void stylus_adc_action(unsigned p0, unsigned p1, unsigned *conv_left)
+{
+	int buf[3];
+
+	/* TODO: Do we really need this? */
+	if (p0 & S3C2410_ADCDAT0_AUTO_PST ||
+	    p1 & S3C2410_ADCDAT1_AUTO_PST) {
+		*conv_left = 1;
+		return;
+	}
+
+	buf[1] = p0;
+	buf[2] = p1;
+
+	switch (ts_filter_chain_feed(ts.chain, &buf[1])) {
+	case 0:
+		/* The filter wants more points. */
+		*conv_left = 1;
+		return;
+	case 1:
+		/* We have a point from the filters or no filtering enabled. */
+		buf[0] = 'P';
+		break;
+	default:
+		TSPRINTK("invalid return value\n");
+	case -1:
+		/* Too much noise. Ignore the event. */
+		ts_filter_chain_clear(ts.chain);
+		writel(WAIT4INT(1), base_addr + S3C2410_ADCTSC);
+		return;
+	};
+
+	if (unlikely(__kfifo_put(ts.event_fifo, (unsigned char *)buf,
+		     sizeof(int) * 3) != sizeof(int) * 3))
+		/* This will only happen if we have a bug. */
+		TSPRINTK("FIFO full\n");
+
+	writel(WAIT4INT(1), base_addr + S3C2410_ADCTSC);
+	mod_timer(&event_send_timer, jiffies + 1);
+
+	return;
+}
+
+/*
+ * The functions for inserting/removing us as a module.
+ */
+
+static int __init s3c2410ts_probe(struct platform_device *pdev)
+{
+	int rc;
+	struct s3c2410_ts_mach_info *info;
+	struct input_dev *input_dev;
+	int ret = 0;
+
+	dev_info(&pdev->dev, "Starting\n");
+
+	info = (struct s3c2410_ts_mach_info *)pdev->dev.platform_data;
+
+	if (!info) {
+		dev_err(&pdev->dev, "No platform data\n");
+		return -EINVAL;
+	}
+
+	base_addr = ioremap(S3C2410_PA_ADC, 0x20);
+	if (base_addr == NULL) {
+		dev_err(&pdev->dev, "Failed to remap register block\n");
+		ret = -ENOMEM;
+		goto bail0;
+	}
+
+	/* If we acutally are a S3C2410: Configure GPIOs */
+	if (!strcmp(pdev->name, "s3c2410-ts"))
+		s3c2410_ts_connect();
+
+	writel(WAIT4INT(0), base_addr + S3C2410_ADCTSC);
+
+	/* Initialise input stuff */
+	memset(&ts, 0, sizeof(struct s3c2410ts));
+
+	ts.adc_client =
+		s3c_adc_register(pdev, adc_selected_f, stylus_adc_action, 1);
+	if (!ts.adc_client) {
+		dev_err(&pdev->dev,
+			"Unable to register s3c2410_ts as s3_adc client\n");
+		iounmap(base_addr);
+		ret = -EIO;
+		goto bail0;
+	}
+
+	input_dev = input_allocate_device();
+	if (!input_dev) {
+		dev_err(&pdev->dev, "Unable to allocate the input device\n");
+		ret = -ENOMEM;
+		goto bail1;
+	}
+
+	ts.dev = input_dev;
+	ts.dev->evbit[0] = BIT_MASK(EV_SYN) | BIT_MASK(EV_KEY) |
+			   BIT_MASK(EV_ABS);
+	ts.dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
+	input_set_abs_params(ts.dev, ABS_X, 0, 0x3FF, 0, 0);
+	input_set_abs_params(ts.dev, ABS_Y, 0, 0x3FF, 0, 0);
+	input_set_abs_params(ts.dev, ABS_PRESSURE, 0, 1, 0, 0);
+
+	ts.dev->name = s3c2410ts_name;
+	ts.dev->id.bustype = BUS_RS232;
+	ts.dev->id.vendor = 0xDEAD;
+	ts.dev->id.product = 0xBEEF;
+	ts.dev->id.version = S3C2410TSVERSION;
+	ts.state = TS_STATE_STANDBY;
+	ts.event_fifo = kfifo_alloc(TS_EVENT_FIFO_SIZE, GFP_KERNEL, NULL);
+	if (IS_ERR(ts.event_fifo)) {
+		ret = -EIO;
+		goto bail2;
+	}
+
+	/* Create the filter chain set up for the 2 coordinates we produce. */
+	ts.chain = ts_filter_chain_create(pdev, info->filter_config, 2);
+
+	if (IS_ERR(ts.chain))
+		goto bail2;
+
+	ts_filter_chain_clear(ts.chain);
+
+	/* Get IRQ. */
+	if (request_irq(IRQ_TC, stylus_updown, 0, "s3c2410_action", ts.dev)) {
+		dev_err(&pdev->dev, "Could not allocate ts IRQ_TC !\n");
+		iounmap(base_addr);
+		ret = -EIO;
+		goto bail3;
+	}
+
+	dev_info(&pdev->dev, "Successfully loaded\n");
+
+	/* All went ok. Register to the input system. */
+	rc = input_register_device(ts.dev);
+	if (rc) {
+		dev_info(&pdev->dev, "Could not register input device\n");
+		ret = -EIO;
+		goto bail4;
+	}
+
+	return 0;
+
+bail4:
+	free_irq(IRQ_TC, ts.dev);
+	iounmap(base_addr);
+	disable_irq(IRQ_TC);
+bail3:
+	ts_filter_chain_destroy(ts.chain);
+	kfifo_free(ts.event_fifo);
+bail2:
+	input_unregister_device(ts.dev);
+bail1:
+	iounmap(base_addr);
+bail0:
+
+	return ret;
+}
+
+static int s3c2410ts_remove(struct platform_device *pdev)
+{
+	disable_irq(IRQ_TC);
+	free_irq(IRQ_TC, ts.dev);
+
+	s3c_adc_release(ts.adc_client);
+	input_unregister_device(ts.dev);
+	iounmap(base_addr);
+
+	ts_filter_chain_destroy(ts.chain);
+
+	kfifo_free(ts.event_fifo);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM
+
+#define TSC_SLEEP	(S3C2410_ADCTSC_PULL_UP_DISABLE | \
+			 S3C2410_ADCTSC_XY_PST(0))
+
+static int s3c2410ts_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	writel(TSC_SLEEP, base_addr + S3C2410_ADCTSC);
+	writel(readl(base_addr + S3C2410_ADCCON) | S3C2410_ADCCON_STDBM,
+	       base_addr + S3C2410_ADCCON);
+	disable_irq(IRQ_TC);
+
+	return 0;
+}
+
+static int s3c2410ts_resume(struct platform_device *pdev)
+{
+	ts_filter_chain_clear(ts.chain);
+	enable_irq(IRQ_TC);
+	writel(WAIT4INT(0), base_addr + S3C2410_ADCTSC);
+
+	return 0;
+}
+
+#else
+#define s3c2410ts_suspend NULL
+#define s3c2410ts_resume  NULL
+#endif
+
+static struct platform_driver s3c2410ts_driver = {
+	.driver = {
+		.name	= "s3c2410-ts",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= s3c2410ts_probe,
+	.remove		= s3c2410ts_remove,
+	.suspend	= s3c2410ts_suspend,
+	.resume		= s3c2410ts_resume,
+};
+
+static struct platform_driver s3c2440ts_driver = {
+	.driver = {
+		.name	= "s3c2440-ts",
+		.owner	= THIS_MODULE,
+	},
+	.probe		= s3c2410ts_probe,
+	.remove		= s3c2410ts_remove,
+	.suspend	= s3c2410ts_suspend,
+	.resume		= s3c2410ts_resume,
+};
+
+static int __init s3c2410ts_init(void)
+{
+	int rc;
+
+	rc = platform_driver_register(&s3c2410ts_driver);
+	if (rc < 0)
+		return rc;
+
+	rc = platform_driver_register(&s3c2440ts_driver);
+	if (rc < 0)
+		platform_driver_unregister(&s3c2410ts_driver);
+
+	return rc;
+}
+
+static void __exit s3c2410ts_exit(void)
+{
+	platform_driver_unregister(&s3c2440ts_driver);
+	platform_driver_unregister(&s3c2410ts_driver);
+}
+
+module_init(s3c2410ts_init);
+module_exit(s3c2410ts_exit);
+
diff --git a/drivers/input/touchscreen/ts_filter.h b/drivers/input/touchscreen/ts_filter.h
new file mode 100644
index 00000000000..632e5fb3f4e
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter.h
@@ -0,0 +1,74 @@
+#ifndef __TS_FILTER_H__
+#define __TS_FILTER_H__
+
+/*
+ * Touchscreen filter.
+ *
+ * (c) 2008,2009 Andy Green <andy@warmcat.com>
+ */
+
+#include <linux/platform_device.h>
+
+#define MAX_TS_FILTER_COORDS		3  /* X, Y and Z (pressure). */
+
+struct ts_filter;
+struct ts_filter_configuration;
+
+/* Operations that a filter can perform. */
+
+struct ts_filter_api {
+	/* Create the filter - mandatory. */
+	struct ts_filter * (*create)(
+		struct platform_device *pdev,
+		const struct ts_filter_configuration *config,
+		int count_coords);
+	/* Destroy the filter - mandatory. */
+	void (*destroy)(struct ts_filter *filter);
+	/* Clear the filter - optional. */
+	void (*clear)(struct ts_filter *filter);
+
+
+	/*
+	 * The next three API functions only make sense if all of them are
+	 * set for a filter. If a filter has the next three methods then
+	 * it can propagate coordinates in the chain.
+	 */
+
+	/*
+	 * Process the filter.
+	 * It returns non-zero if the filter reaches an error.
+	 */
+	int (*process)(struct ts_filter *filter, int *coords);
+	/*
+	 * Is the filter ready to return a point?
+	 * Please do not code side effects in this function.
+	 */
+	int (*haspoint)(struct ts_filter *filter);
+	/*
+	 * Get a point.
+	 * Do not call unless the filter actually has a point to deliver.
+	 */
+	void (*getpoint)(struct ts_filter *filter, int *coords);
+
+	/*
+	 * Scale the points - optional.
+	 * A filter could only scale coordinates.
+	 */
+	void (*scale)(struct ts_filter *filter, int *coords);
+};
+
+/*
+ * Generic filter configuration. Actual configurations have this structure
+ * as a member.
+ */
+struct ts_filter_configuration {
+};
+
+struct ts_filter {
+	/* Operations for this filter. */
+	const struct ts_filter_api *api;
+	/* Number of coordinates to process. */
+	int count_coords;
+};
+
+#endif
diff --git a/drivers/input/touchscreen/ts_filter_chain.c b/drivers/input/touchscreen/ts_filter_chain.c
new file mode 100644
index 00000000000..17793ace144
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_chain.c
@@ -0,0 +1,183 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (c) 2008,2009 Andy Green <andy@warmcat.com>
+ */
+
+#include <linux/kernel.h>
+#include <linux/device.h>
+
+#include "ts_filter_chain.h"
+#include "ts_filter.h"
+
+/*
+ * Tux, would you like the following function in /lib?
+ * It helps us avoid silly code.
+ */
+
+/**
+ * sptrlen - Count how many non-null pointers are in a pointer array
+ * @arr: The array of pointers
+ */
+static int sptrlen(const void *arr)
+{
+	/* All pointers have the same size. */
+	const int **p = (const int **)arr;
+	int len = 0;
+
+	while (*(p++))
+		len++;
+
+	return len;
+}
+
+
+struct ts_filter_chain {
+	/* All of the filters. */
+	struct ts_filter **arr;
+	/* Filters that can propagate values in the chain. */
+	struct ts_filter **pchain;
+	/* Length of the pchain array. */
+	int pchain_len;
+	/* FIXME: Add a spinlock and use it. */
+};
+
+struct ts_filter_chain *ts_filter_chain_create(
+	struct platform_device *pdev,
+	const struct ts_filter_chain_configuration conf[],
+	int count_coords)
+{
+	struct ts_filter_chain *c;
+	int count = 0;
+	int len;
+
+	BUG_ON((count_coords < 1));
+	BUG_ON(count_coords > MAX_TS_FILTER_COORDS);
+
+	c = kzalloc(sizeof(struct ts_filter_chain), GFP_KERNEL);
+	if (!c)
+		goto create_err_1;
+
+	len = (sptrlen(conf) + 1);
+	/* Memory for two null-terminated arrays of filters. */
+	c->arr = kzalloc(2 * sizeof(struct ts_filter *) * len, GFP_KERNEL);
+	if (!c->arr)
+		goto create_err_1;
+	c->pchain = c->arr + len;
+
+	while (conf->api) {
+		/* TODO: Can we get away with only sending pdev->dev? */
+		struct ts_filter *f =
+			(conf->api->create)(pdev, conf->config, count_coords);
+		if (!f) {
+			dev_info(&pdev->dev, "Filter %d creation failed\n",
+				 count);
+			goto create_err_2;
+		}
+
+		f->api = conf->api;
+		c->arr[count++] = f;
+
+		if (f->api->haspoint && f->api->getpoint && f->api->process)
+			c->pchain[c->pchain_len++] = f;
+
+		conf++;
+	}
+
+	dev_info(&pdev->dev, "%d filter(s) initialized\n", count);
+
+	return c;
+
+create_err_2:
+	ts_filter_chain_destroy(c); /* Also frees c. */
+create_err_1:
+	dev_info(&pdev->dev, "Error in filter chain initialization\n");
+	/*
+	 * FIXME: Individual filters have to return errors this way.
+	 * We only have to forward the errors we find.
+	 */
+	return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL_GPL(ts_filter_chain_create);
+
+void ts_filter_chain_destroy(struct ts_filter_chain *c)
+{
+	if (c->arr) {
+		struct ts_filter **a = c->arr;
+		while (*a) {
+			((*a)->api->destroy)(*a);
+			a++;
+		}
+		kfree(c->arr);
+	}
+	kfree(c);
+}
+EXPORT_SYMBOL_GPL(ts_filter_chain_destroy);
+
+void ts_filter_chain_clear(struct ts_filter_chain *c)
+{
+	struct ts_filter **a = c->arr;
+
+	while (*a) {
+		if ((*a)->api->clear)
+			((*a)->api->clear)(*a);
+		a++;
+	}
+}
+EXPORT_SYMBOL_GPL(ts_filter_chain_clear);
+
+static void ts_filter_chain_scale(struct ts_filter_chain *c, int *coords)
+{
+	struct ts_filter **a = c->arr;
+	while (*a) {
+		if ((*a)->api->scale)
+			((*a)->api->scale)(*a, coords);
+		a++;
+	}
+}
+
+int ts_filter_chain_feed(struct ts_filter_chain *c, int *coords)
+{
+	int len = c->pchain_len;
+	int i = len - 1;
+
+	if (!c->pchain[0])
+		return 1; /* Nothing to do. */
+
+	BUG_ON(c->pchain[0]->api->haspoint(c->pchain[0]));
+
+	if (c->pchain[0]->api->process(c->pchain[0], coords))
+		return -1;
+
+	while (i >= 0 && i < len) {
+		if (c->pchain[i]->api->haspoint(c->pchain[i])) {
+			c->pchain[i]->api->getpoint(c->pchain[i], coords);
+			if (++i < len &&
+			    c->pchain[i]->api->process(c->pchain[i], coords))
+				return -1; /* Error. */
+		} else {
+			i--;
+		}
+	}
+
+	if (i >= 0) {	/* Same as i == len. */
+		ts_filter_chain_scale(c, coords);
+		return 1;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(ts_filter_chain_feed);
+
diff --git a/drivers/input/touchscreen/ts_filter_chain.h b/drivers/input/touchscreen/ts_filter_chain.h
new file mode 100644
index 00000000000..065a6a026d2
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_chain.h
@@ -0,0 +1,58 @@
+#ifndef __TS_FILTER_CHAIN_H__
+#define __TS_FILTER_CHAIN_H__
+
+/*
+ * Touchscreen filter chains.
+ *
+ * (c) 2008,2009 Andy Green <andy@warmcat.com>
+ */
+
+#include "ts_filter.h"
+
+#include <linux/err.h>
+
+struct ts_filter_chain_configuration {
+	/* API to use. */
+	const struct ts_filter_api *api;
+	/* Generic filter configuration. Different for each filter. */
+	const struct ts_filter_configuration *config;
+};
+
+struct ts_filter_chain;
+
+#ifdef CONFIG_TOUCHSCREEN_FILTER
+
+/*
+ * Create a filter chain. It will allocate an array of
+ * null-terminated pointers to filters. On error it will return
+ * an error you can check with IS_ERR.
+ */
+extern struct ts_filter_chain *ts_filter_chain_create(
+	struct platform_device *pdev,
+	const struct ts_filter_chain_configuration conf[],
+	int count_coords);
+
+/* Destroy the chain. */
+extern void ts_filter_chain_destroy(struct ts_filter_chain *c);
+
+/* Clear the filter chain. */
+extern void ts_filter_chain_clear(struct ts_filter_chain *c);
+
+/*
+ * Try to get one point. Returns 0 if no points are available.
+ * coords will be used as temporal space, thus you supply a point
+ * using coords but you shouldn't rely on its value on return unless
+ * it returns a nonzero value that is not -1.
+ * If one of the filters find an error then this function will
+ * return -1.
+ */
+int ts_filter_chain_feed(struct ts_filter_chain *c, int *coords);
+
+#else /* !CONFIG_TOUCHSCREEN_FILTER */
+#define ts_filter_chain_create(pdev, config, count_coords) (NULL)
+#define ts_filter_chain_destroy(c) do { } while (0)
+#define ts_filter_chain_clear(c) do { } while (0)
+#define ts_filter_chain_feed(c, coords) (1)
+#endif
+
+#endif
diff --git a/drivers/input/touchscreen/ts_filter_group.c b/drivers/input/touchscreen/ts_filter_group.c
new file mode 100644
index 00000000000..722e8dfbdae
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_group.c
@@ -0,0 +1,330 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) 2008,2009 by Openmoko, Inc.
+ * Author: Nelson Castillo <arhuaco@freaks-unidos.net>
+ * All rights reserved.
+ *
+ *
+ * This filter is useful to reject samples that are not reliable. We consider
+ * that a sample is not reliable if it deviates form the Majority.
+ * This filter mixes information from all the available dimensions. It means
+ * that for two dimensions we draw a rectangle where the thought-to-be good
+ * points can be found.
+ *
+ * The implementation would be more efficient with a double-linked list but
+ * let's keep it simple for now.
+ *
+ * 1) We collect S samples and keep it in sorted sets.
+ *  - Points that are "close enough" are considered to be in the same set.
+ *    We don't actually keep the sets but ranges of points.
+ *
+ * 2) For each dimension:
+ *  - We choose the range with more elements. If more than "threshold"
+ *    points are in this range we use the minimum and the maximum point
+ *    of the range to define the valid range for this dimension [min, max],
+ *    otherwise we discard all the points and the ranges and go to step 1.
+ *
+ * 3) We consider the unsorted S samples and try to feed them to the next
+ *    filter in the chain. If one of the points of each sample
+ *    is not in the allowed range for its dimension we discard the sample.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include "ts_filter_group.h"
+
+struct coord_range {
+	int min;	/* Minimum value of the range. */
+	int max;	/* Maximum value of the range  */
+	int N;		/* Number of points in the range. */
+};
+
+struct ts_filter_group {
+	/* Private filter configuration. */
+	struct ts_filter_group_configuration *config;
+	/* Filter API. */
+	struct ts_filter tsf;
+
+	int N;			/* How many samples we have. */
+	int *samples[MAX_TS_FILTER_COORDS];	/* The samples: our input. */
+
+	/* Temporal values that help us compute range_min and range_max. */
+	struct coord_range *ranges[MAX_TS_FILTER_COORDS];	/* Ranges. */
+	int n_ranges[MAX_TS_FILTER_COORDS];		/* Number of ranges */
+
+	/* Computed ranges that help us filter the points. */
+	int range_max[MAX_TS_FILTER_COORDS];	/* Max. computed ranges. */
+	int range_min[MAX_TS_FILTER_COORDS];	/* Min. computed ranges. */
+
+	int tries_left;		/* We finish if we can't get enough samples. */
+	int ready;		/* If we are ready to deliver samples. */
+	int result;		/* Index of the point being returned. */
+};
+
+#define ts_filter_to_filter_group(f) \
+	container_of(f, struct ts_filter_group, tsf)
+
+
+static void ts_filter_group_clear_internal(struct ts_filter_group *tsfg,
+					   int attempts)
+{
+	int n;
+	tsfg->N = 0;
+	tsfg->tries_left = attempts;
+	tsfg->ready = 0;
+	tsfg->result = 0;
+	for (n = 0; n < tsfg->tsf.count_coords; n++)
+		tsfg->n_ranges[n] = 0;
+}
+
+static void ts_filter_group_clear(struct ts_filter *tsf)
+{
+	struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf);
+
+	ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
+}
+
+static struct ts_filter *ts_filter_group_create(
+	struct platform_device *pdev,
+	const struct ts_filter_configuration *conf,
+	int count_coords)
+{
+	struct ts_filter_group *tsfg;
+	int i;
+
+	tsfg = kzalloc(sizeof(struct ts_filter_group), GFP_KERNEL);
+	if (!tsfg)
+		return NULL;
+
+	tsfg->config = container_of(conf,
+				    struct ts_filter_group_configuration,
+				    config);
+	tsfg->tsf.count_coords = count_coords;
+
+	BUG_ON(tsfg->config->attempts <= 0);
+	BUG_ON(tsfg->config->length < tsfg->config->threshold);
+
+	tsfg->samples[0] = kmalloc(count_coords * sizeof(int) *
+				   tsfg->config->length, GFP_KERNEL);
+	if (!tsfg->samples[0]) {
+		kfree(tsfg);
+		return NULL;
+	}
+	for (i = 1; i < count_coords; ++i)
+		tsfg->samples[i] = tsfg->samples[0] + i * tsfg->config->length;
+
+	tsfg->ranges[0] = kmalloc(count_coords * sizeof(struct coord_range) *
+				  tsfg->config->length, GFP_KERNEL);
+	if (!tsfg->ranges[0]) {
+		kfree(tsfg->samples[0]);
+		kfree(tsfg);
+		return NULL;
+	}
+	for (i = 1; i < count_coords; ++i)
+		tsfg->ranges[i] = tsfg->ranges[0] + i * tsfg->config->length;
+
+	ts_filter_group_clear_internal(tsfg, tsfg->config->attempts);
+
+	dev_info(&pdev->dev, "Created Group filter len:%d coords:%d close:%d "
+		 "thresh:%d\n", tsfg->config->length, count_coords,
+		 tsfg->config->close_enough, tsfg->config->threshold);
+
+	return &tsfg->tsf;
+}
+
+static void ts_filter_group_destroy(struct ts_filter *tsf)
+{
+	struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf);
+
+	kfree(tsfg->samples[0]);
+	kfree(tsfg->ranges[0]);
+	kfree(tsf);
+}
+
+static void ts_filter_group_prepare_next(struct ts_filter *tsf);
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+#define IN_RANGE(c, r) ((c) >= (r).min - tsfg->config->close_enough && \
+			(c) <= (r).max + tsfg->config->close_enough)
+
+static void delete_spot(struct coord_range *v, int n, int size)
+{
+	int i;
+	for (i = n; i < size - 1; ++i)
+		v[i] = v[i + 1];
+}
+
+static int ts_filter_group_process(struct ts_filter *tsf, int *coords)
+{
+	struct ts_filter_group *tsfg = ts_filter_to_filter_group(tsf);
+	int n;
+	int j;
+
+	BUG_ON(tsfg->N >= tsfg->config->length);
+	BUG_ON(tsfg->ready);
+
+	for (n = 0; n < tsfg->tsf.count_coords; n++) {
+		int i;
+		struct coord_range *range = tsfg->ranges[n];
+		int *n_ranges = &tsfg->n_ranges[n];
+		int found = 0;
+
+		tsfg->samples[n][tsfg->N] = coords[n];
+
+		for (i = 0; i < *n_ranges; ++i) {
+			if (IN_RANGE(coords[n], range[i])) {
+				range[i].min  = MIN(range[i].min, coords[n]);
+				range[i].max  = MAX(range[i].max, coords[n]);
+				range[i].N++;
+				found = 1;
+				break;
+			} else if (coords[n] <= range[i].min)
+				break;	/* We need to insert a range. */
+		}
+		if (found) { /* We might need to melt ranges. */
+			if (i && range[i - 1].max + tsfg->config->close_enough
+			    >= range[i].min) {
+				BUG_ON(range[i - 1].max >= range[i].max);
+				range[i - 1].max = range[i].max;
+				range[i - 1].N += range[i].N;
+				delete_spot(range, i, *n_ranges);
+				(*n_ranges)--;
+				i--;
+			}
+			if (i < *n_ranges - 1 && range[i + 1].min -
+			    tsfg->config->close_enough <= range[i].max) {
+				range[i].max = range[i + 1].max;
+				range[i].N += range[i + 1].N;
+				delete_spot(range, i + 1, *n_ranges);
+				(*n_ranges)--;
+			}
+		} else {
+			BUG_ON((*n_ranges) >= tsfg->config->length);
+			(*n_ranges)++;
+			for (j = *n_ranges - 1; j > i; --j)
+				range[j] = range[j - 1];
+			range[i].N = 1;
+			range[i].min = coords[n];
+			range[i].max = coords[n];
+		}
+	}
+
+	if (++tsfg->N < tsfg->config->length)
+		return 0;
+
+	for (n = 0; n < tsfg->tsf.count_coords; ++n) {
+		int best = 0;
+		for (j = 1; j < tsfg->n_ranges[n]; ++j)
+			if (tsfg->ranges[n][best].N  < tsfg->ranges[n][j].N)
+				best = j;
+		if (tsfg->ranges[n][best].N < tsfg->config->threshold) {
+			/* This set of points is not good enough for us. */
+			if (--tsfg->tries_left) {
+				ts_filter_group_clear_internal
+					(tsfg, tsfg->tries_left);
+				/* No errors but we need more samples. */
+				return 0;
+			}
+			return 1; /* We give up: error. */
+		}
+		tsfg->range_min[n] = tsfg->ranges[n][best].min;
+		tsfg->range_max[n] = tsfg->ranges[n][best].max;
+	}
+
+	ts_filter_group_prepare_next(tsf);
+
+	return 0;
+}
+
+/*
+ * This private function prepares a point that will be returned
+ * in ts_filter_group_getpoint if it is available. It updates
+ * the priv->ready state also.
+ */
+static void ts_filter_group_prepare_next(struct ts_filter *tsf)
+{
+	struct ts_filter_group *priv = ts_filter_to_filter_group(tsf);
+	int n;
+
+	while (priv->result < priv->N) {
+		for (n = 0; n < priv->tsf.count_coords; ++n) {
+			if (priv->samples[n][priv->result] <
+			    priv->range_min[n] ||
+			    priv->samples[n][priv->result] > priv->range_max[n])
+				break;
+		}
+
+		if (n == priv->tsf.count_coords) /* Sample is OK. */
+			break;
+
+		priv->result++;
+	}
+
+	if (unlikely(priv->result >= priv->N)) { /* No sample to deliver. */
+		ts_filter_group_clear_internal(priv, priv->config->attempts);
+		priv->ready = 0;
+	} else {
+		priv->ready = 1;
+	}
+}
+
+static int ts_filter_group_haspoint(struct ts_filter *tsf)
+{
+	struct ts_filter_group *priv = ts_filter_to_filter_group(tsf);
+
+	return priv->ready;
+}
+
+static void ts_filter_group_getpoint(struct ts_filter *tsf, int *point)
+{
+	struct ts_filter_group *priv = ts_filter_to_filter_group(tsf);
+	int n;
+
+	BUG_ON(!priv->ready);
+
+	for (n = 0; n < priv->tsf.count_coords; n++)
+		point[n] = priv->samples[n][priv->result];
+
+	priv->result++;
+
+	/* This call will update priv->ready. */
+	ts_filter_group_prepare_next(tsf);
+}
+
+/*
+ * Get ready to process the next batch of points, forget
+ * points we could have delivered.
+ */
+static void ts_filter_group_scale(struct ts_filter *tsf, int *coords)
+{
+	struct ts_filter_group *priv = ts_filter_to_filter_group(tsf);
+
+	ts_filter_group_clear_internal(priv, priv->config->attempts);
+}
+
+const struct ts_filter_api ts_filter_group_api = {
+	.create =	ts_filter_group_create,
+	.destroy =	ts_filter_group_destroy,
+	.clear =	ts_filter_group_clear,
+	.process =	ts_filter_group_process,
+	.haspoint =	ts_filter_group_haspoint,
+	.getpoint =	ts_filter_group_getpoint,
+	.scale =	ts_filter_group_scale,
+};
+EXPORT_SYMBOL_GPL(ts_filter_group_api);
+
diff --git a/drivers/input/touchscreen/ts_filter_group.h b/drivers/input/touchscreen/ts_filter_group.h
new file mode 100644
index 00000000000..d1e3590e936
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_group.h
@@ -0,0 +1,36 @@
+#ifndef __TS_FILTER_GROUP_H__
+#define __TS_FILTER_GROUP_H__
+
+#include "ts_filter.h"
+
+/*
+ * Touchscreen group filter.
+ *
+ * Copyright (C) 2008,2009 by Openmoko, Inc.
+ * Author: Nelson Castillo <arhuaco@freaks-unidos.net>
+ *
+ */
+
+struct ts_filter_group_configuration {
+	/* Size of the filter. */
+	int length;
+	/*
+	 * If two points are separated by this distance or less they
+	 * are considered to be members of the same group.
+	 */
+	int close_enough;
+	/* Minimum allowed size for the biggest group in the sample set. */
+	int threshold;
+	/*
+	 * Number of times we try to get a group of points with at least
+	 * threshold points.
+	 */
+	int attempts;
+
+	/* Generic filter configuration. */
+	struct ts_filter_configuration config;
+};
+
+extern const struct ts_filter_api ts_filter_group_api;
+
+#endif
diff --git a/drivers/input/touchscreen/ts_filter_linear.c b/drivers/input/touchscreen/ts_filter_linear.c
new file mode 100644
index 00000000000..7718bbc6e6d
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_linear.c
@@ -0,0 +1,212 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (C) 2008,2009 by Openmoko, Inc.
+ * Author: Nelson Castillo <arhuaco@freaks-unidos.net>
+ * All rights reserved.
+ *
+ * Linearly scale touchscreen values.
+ *
+ * Expose the TS_FILTER_LINEAR_NCONSTANTS for the linear transformation
+ * using sysfs.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+#include "ts_filter_linear.h"
+
+struct ts_filter_linear;
+
+/* Sysfs code. */
+
+struct const_obj {
+	/* The actual private object. */
+	struct ts_filter_linear *tsfl;
+	/* Our kobject. */
+	struct kobject kobj;
+};
+
+#define to_const_obj(x) container_of(x, struct const_obj, kobj)
+
+struct const_attribute {
+	struct attribute attr;
+	ssize_t (*show)(struct const_obj *const, struct const_attribute *attr,
+			char *buf);
+	ssize_t (*store)(struct const_obj *const, struct const_attribute *attr,
+			 const char *buf, size_t count);
+};
+
+#define to_const_attr(x) container_of(x, struct const_attribute, attr)
+
+
+/* Private linear filter structure. */
+
+struct ts_filter_linear {
+	/* Private configuration for this filter. */
+	struct ts_filter_linear_configuration *config;
+
+	/* Generic filter API. */
+	struct ts_filter tsf;
+
+	/* Linear constants for the transformation. */
+	int constants[TS_FILTER_LINEAR_NCONSTANTS];
+
+	/* Sysfs. */
+
+	/* Our const_object. */
+	struct const_obj c_obj;
+	/* Our type. We will stick operations to it. */
+	struct kobj_type const_ktype;
+	/* Attrs. of the virtual files. */
+	struct const_attribute kattrs[TS_FILTER_LINEAR_NCONSTANTS];
+	/* Default Attrs. Always NULL for us. */
+	struct attribute *attrs[TS_FILTER_LINEAR_NCONSTANTS + 1];
+	/* Storage for the name of the virtual files. */
+	char attr_names[TS_FILTER_LINEAR_NCONSTANTS][2];
+};
+
+#define ts_filter_to_filter_linear(f) \
+	container_of(f, struct ts_filter_linear, tsf)
+
+/* Sysfs functions. */
+
+static ssize_t const_attr_show(struct kobject *kobj,
+			       struct attribute *attr,
+			       char *buf)
+{
+	struct const_attribute *a = to_const_attr(attr);
+
+	return a->show(to_const_obj(kobj), a, buf);
+}
+
+static ssize_t const_attr_store(struct kobject *kobj,
+				struct attribute *attr,
+				const char *buf, size_t len)
+{
+	struct const_attribute *a = to_const_attr(attr);
+
+	return a->store(to_const_obj(kobj), a, buf, len);
+}
+
+static struct sysfs_ops const_sysfs_ops = {
+	.show =		const_attr_show,
+	.store =	const_attr_store,
+};
+
+static void const_release(struct kobject *kobj)
+{
+	kfree(to_const_obj(kobj)->tsfl);
+}
+
+static ssize_t const_show(struct const_obj *obj, struct const_attribute *attr,
+			  char *buf)
+{
+	int who;
+
+	sscanf(attr->attr.name, "%d", &who);
+	return sprintf(buf, "%d\n", obj->tsfl->constants[who]);
+}
+
+static ssize_t const_store(struct const_obj *obj, struct const_attribute *attr,
+			   const char *buf, size_t count)
+{
+	int who;
+
+	sscanf(attr->attr.name, "%d", &who);
+	sscanf(buf, "%d", &obj->tsfl->constants[who]);
+	return count;
+}
+
+/* Filter functions. */
+
+static struct ts_filter *ts_filter_linear_create(
+	struct platform_device *pdev,
+	const struct ts_filter_configuration *conf,
+	int count_coords)
+{
+	struct ts_filter_linear *tsfl;
+	int i;
+	int ret;
+
+	tsfl = kzalloc(sizeof(struct ts_filter_linear), GFP_KERNEL);
+	if (!tsfl)
+		return NULL;
+
+	tsfl->config = container_of(conf,
+				    struct ts_filter_linear_configuration,
+				    config);
+
+	tsfl->tsf.count_coords = count_coords;
+
+	for (i = 0; i < TS_FILTER_LINEAR_NCONSTANTS; ++i) {
+		tsfl->constants[i] = tsfl->config->constants[i];
+
+		/* sysfs */
+		sprintf(tsfl->attr_names[i], "%d", i);
+		tsfl->kattrs[i].attr.name = tsfl->attr_names[i];
+		tsfl->kattrs[i].attr.mode = 0666;
+		tsfl->kattrs[i].show = const_show;
+		tsfl->kattrs[i].store = const_store;
+		tsfl->attrs[i] = &tsfl->kattrs[i].attr;
+	}
+	tsfl->attrs[i] = NULL;
+
+	tsfl->const_ktype.sysfs_ops = &const_sysfs_ops;
+	tsfl->const_ktype.release = const_release;
+	tsfl->const_ktype.default_attrs = tsfl->attrs;
+	tsfl->c_obj.tsfl = tsfl; /* kernel frees tsfl in const_release */
+
+	ret = kobject_init_and_add(&tsfl->c_obj.kobj, &tsfl->const_ktype,
+				   &pdev->dev.kobj, "calibration");
+	if (ret) {
+		kobject_put(&tsfl->c_obj.kobj);
+		return NULL;
+	}
+
+	dev_info(&pdev->dev, "Created Linear filter coords:%d\n", count_coords);
+
+	return &tsfl->tsf;
+}
+
+static void ts_filter_linear_destroy(struct ts_filter *tsf)
+{
+	struct ts_filter_linear *tsfl = ts_filter_to_filter_linear(tsf);
+
+	/* Kernel frees tsfl in const_release. */
+	kobject_put(&tsfl->c_obj.kobj);
+}
+
+static void ts_filter_linear_scale(struct ts_filter *tsf, int *coords)
+{
+	struct ts_filter_linear *tsfl = ts_filter_to_filter_linear(tsf);
+
+	int *k = tsfl->constants;
+	int c0 = coords[tsfl->config->coord0];
+	int c1 = coords[tsfl->config->coord1];
+
+	coords[tsfl->config->coord0] = (k[2] + k[0] * c0 + k[1] * c1) / k[6];
+	coords[tsfl->config->coord1] = (k[5] + k[3] * c0 + k[4] * c1) / k[6];
+}
+
+const struct ts_filter_api ts_filter_linear_api = {
+	.create =	ts_filter_linear_create,
+	.destroy =	ts_filter_linear_destroy,
+	.scale =	ts_filter_linear_scale,
+};
+EXPORT_SYMBOL_GPL(ts_filter_linear_api);
+
diff --git a/drivers/input/touchscreen/ts_filter_linear.h b/drivers/input/touchscreen/ts_filter_linear.h
new file mode 100644
index 00000000000..82df3d25b50
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_linear.h
@@ -0,0 +1,31 @@
+#ifndef __TS_FILTER_LINEAR_H__
+#define __TS_FILTER_LINEAR_H__
+
+#include "ts_filter.h"
+#include <linux/kobject.h>
+
+/*
+ * Touchscreen linear filter.
+ *
+ * Copyright (C) 2008,2009 by Openmoko, Inc.
+ * Author: Nelson Castillo <arhuaco@freaks-unidos.net>
+ *
+ */
+
+#define TS_FILTER_LINEAR_NCONSTANTS 7
+
+struct ts_filter_linear_configuration {
+	/* Calibration constants. */
+	int constants[TS_FILTER_LINEAR_NCONSTANTS];
+	/* First coordinate. */
+	int coord0;
+	/* Second coordinate. */
+	int coord1;
+
+	/* Generic filter configuration. */
+	struct ts_filter_configuration config;
+};
+
+extern const struct ts_filter_api ts_filter_linear_api;
+
+#endif
diff --git a/drivers/input/touchscreen/ts_filter_mean.c b/drivers/input/touchscreen/ts_filter_mean.c
new file mode 100644
index 00000000000..0c604321713
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_mean.c
@@ -0,0 +1,174 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (c) 2008,2009
+ *       Andy Green <andy@warmcat.com>
+ *       Nelson Castillo <arhuaco@freaks-unidos.net>
+ *
+ * Simple mean filter.
+ *
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+
+#include "ts_filter_mean.h"
+
+struct ts_filter_mean {
+	/* Copy of the private filter configuration. */
+	struct ts_filter_mean_configuration *config;
+	/* Filter API. */
+	struct ts_filter tsf;
+
+	/* Index on a circular buffer. */
+	int curr;
+	/* Useful to tell if the circular buffer is full(read:ready). */
+	int count;
+	/* Sumation used to compute the mean. */
+	int sum[MAX_TS_FILTER_COORDS];
+	/* Keep point values and decrement them from the sum on time. */
+	int *fifo[MAX_TS_FILTER_COORDS];
+	/* Store the output of this filter. */
+	int ready;
+};
+
+#define ts_filter_to_filter_mean(f) container_of(f, struct ts_filter_mean, tsf)
+
+
+static void ts_filter_mean_clear(struct ts_filter *tsf);
+
+static struct ts_filter *ts_filter_mean_create(
+	struct platform_device *pdev,
+	const struct ts_filter_configuration *conf,
+	int count_coords)
+{
+	struct ts_filter_mean *priv;
+	int *v;
+	int n;
+
+	priv = kzalloc(sizeof(struct ts_filter_mean), GFP_KERNEL);
+	if (!priv)
+		return NULL;
+
+	priv->tsf.count_coords = count_coords;
+	priv->config = container_of(conf,
+				    struct ts_filter_mean_configuration,
+				    config);
+
+	BUG_ON(priv->config->length <= 0);
+
+	v = kmalloc(priv->config->length * sizeof(int) * count_coords,
+		    GFP_KERNEL);
+	if (!v)
+		return NULL;
+
+	for (n = 0; n < count_coords; n++) {
+		priv->fifo[n] = v;
+		v += priv->config->length;
+	}
+
+	ts_filter_mean_clear(&priv->tsf);
+
+	dev_info(&pdev->dev, "Created Mean filter len:%d coords:%d\n",
+		 priv->config->length, count_coords);
+
+	return &priv->tsf;
+}
+
+static void ts_filter_mean_destroy(struct ts_filter *tsf)
+{
+	struct ts_filter_mean *priv = ts_filter_to_filter_mean(tsf);
+
+	kfree(priv->fifo[0]); /* first guy has pointer from kmalloc */
+	kfree(tsf);
+}
+
+static void ts_filter_mean_clear(struct ts_filter *tsf)
+{
+	struct ts_filter_mean *priv = ts_filter_to_filter_mean(tsf);
+
+	priv->count = 0;
+	priv->curr = 0;
+	priv->ready = 0;
+	memset(priv->sum, 0, tsf->count_coords * sizeof(int));
+}
+
+static int ts_filter_mean_process(struct ts_filter *tsf, int *coords)
+{
+	struct ts_filter_mean *priv = ts_filter_to_filter_mean(tsf);
+	int n;
+
+	BUG_ON(priv->ready);
+
+	for (n = 0; n < tsf->count_coords; n++) {
+		priv->sum[n] += coords[n];
+		priv->fifo[n][priv->curr] = coords[n];
+	}
+
+	if (priv->count + 1 == priv->config->length)
+		priv->ready = 1;
+	else
+		priv->count++;
+
+	priv->curr = (priv->curr + 1) % priv->config->length;
+
+	return 0; /* No error. */
+}
+
+static int ts_filter_mean_haspoint(struct ts_filter *tsf)
+{
+	struct ts_filter_mean *priv = ts_filter_to_filter_mean(tsf);
+
+	return priv->ready;
+}
+
+static void ts_filter_mean_getpoint(struct ts_filter *tsf, int *point)
+{
+	struct ts_filter_mean *priv = ts_filter_to_filter_mean(tsf);
+	int n;
+
+	BUG_ON(!priv->ready);
+
+	for (n = 0; n < tsf->count_coords; n++) {
+		point[n] = priv->sum[n];
+		priv->sum[n] -= priv->fifo[n][priv->curr];
+	}
+
+	priv->ready = 0;
+}
+
+static void ts_filter_mean_scale(struct ts_filter *tsf, int *coords)
+{
+	int n;
+	struct ts_filter_mean *priv = ts_filter_to_filter_mean(tsf);
+
+	for (n = 0; n < tsf->count_coords; n++) {
+		coords[n] += priv->config->length >> 1; /* Rounding. */
+		coords[n] /= priv->config->length;
+	}
+}
+
+const struct ts_filter_api ts_filter_mean_api = {
+	.create =	ts_filter_mean_create,
+	.destroy =	ts_filter_mean_destroy,
+	.clear =	ts_filter_mean_clear,
+	.process =	ts_filter_mean_process,
+	.scale =	ts_filter_mean_scale,
+	.haspoint =	ts_filter_mean_haspoint,
+	.getpoint =	ts_filter_mean_getpoint,
+};
+EXPORT_SYMBOL_GPL(ts_filter_mean_api);
+
diff --git a/drivers/input/touchscreen/ts_filter_mean.h b/drivers/input/touchscreen/ts_filter_mean.h
new file mode 100644
index 00000000000..80f9b215dff
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_mean.h
@@ -0,0 +1,28 @@
+#ifndef __TS_FILTER_MEAN_H__
+#define __TS_FILTER_MEAN_H__
+
+#include "ts_filter.h"
+
+/*
+ * Touchscreen filter.
+ *
+ * mean
+ *
+ * (c) 2008,2009
+ *     Andy Green <andy@warmcat.com>
+ *     Nelson Castillo <arhuaco@freaks-unidos.net>
+ */
+
+/* Configuration for this filter. */
+struct ts_filter_mean_configuration {
+	/* Number of points for the mean. */
+	int length;
+
+	/* Generic filter configuration. */
+	struct ts_filter_configuration config;
+};
+
+/* API functions for the mean filter */
+extern const struct ts_filter_api ts_filter_mean_api;
+
+#endif /* __TS_FILTER_MEAN_H__ */
diff --git a/drivers/input/touchscreen/ts_filter_median.c b/drivers/input/touchscreen/ts_filter_median.c
new file mode 100644
index 00000000000..6f8aae5941d
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_median.c
@@ -0,0 +1,261 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Copyright (c) 2008 Andy Green <andy@warmcat.com>
+ *
+ *
+ * Median averaging stuff.  We sort incoming raw samples into an array of
+ * MEDIAN_SIZE length, discarding the oldest sample each time once we are full.
+ * We then return the sum of the middle three samples for X and Y.  It means
+ * the final result must be divided by (3 * scaling factor) to correct for
+ * avoiding the repeated /3.
+ *
+ * This strongly rejects brief excursions away from a central point that is
+ * sticky in time compared to the excursion duration.
+ *
+ * Thanks to Dale Schumacher (who wrote some example code) and Carl-Daniel
+ * Halifinger who pointed out this would be a good method.
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include "ts_filter_median.h"
+
+struct ts_filter_median {
+	/* Private configuration. */
+	struct ts_filter_median_configuration *config;
+	/* Generic Filter API. */
+	struct ts_filter tsf;
+
+	/* Count raw samples we get. */
+	int samples_count;
+	/*
+	 * Remember the last coordinates we got in order to know if
+	 * we are moving slow or fast.
+	 */
+	int last_issued[MAX_TS_FILTER_COORDS];
+	/* How many samples in the sort buffer are valid. */
+	int valid;
+	/* Samples taken for median in sorted form. */
+	int *sort[MAX_TS_FILTER_COORDS];
+	/* Samples taken for median. */
+	int *fifo[MAX_TS_FILTER_COORDS];
+	/* Where we are in the fifo sample memory. */
+	int pos;
+	/* Do we have a sample to deliver? */
+	int ready;
+};
+
+#define ts_filter_to_filter_median(f) \
+	container_of(f, struct ts_filter_median, tsf)
+
+
+static void ts_filter_median_insert(int *p, int sample, int count)
+{
+	int n;
+
+	/* Search through what we got so far to find where to put sample. */
+	for (n = 0; n < count; n++)
+		if (sample < p[n]) {	/* We met somebody bigger than us? */
+			/* Starting from the end, push bigger guys down one. */
+			for (count--; count >= n; count--)
+				p[count + 1] = p[count];
+			p[n] = sample; /* Put us in place of first bigger. */
+			return;
+		}
+
+	p[count] = sample; /* Nobody was bigger than us, add us on the end. */
+}
+
+static void ts_filter_median_del(int *p, int value, int count)
+{
+	int index;
+
+	for (index = 0; index < count; index++)
+		if (p[index] == value) {
+			for (; index < count; index++)
+				p[index] = p[index + 1];
+			return;
+		}
+}
+
+
+static void ts_filter_median_clear(struct ts_filter *tsf)
+{
+	struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf);
+
+	tsfm->pos = 0;
+	tsfm->valid = 0;
+	tsfm->ready = 0;
+	memset(&tsfm->last_issued[0], 1, tsf->count_coords * sizeof(int));
+}
+
+static struct ts_filter *ts_filter_median_create(
+	struct platform_device *pdev,
+	const struct ts_filter_configuration *conf,
+	int count_coords)
+{
+	int *p;
+	int n;
+	struct ts_filter_median *tsfm = kzalloc(sizeof(struct ts_filter_median),
+								    GFP_KERNEL);
+
+	if (!tsfm)
+		return NULL;
+
+	tsfm->config = container_of(conf,
+				    struct ts_filter_median_configuration,
+				    config);
+
+	tsfm->tsf.count_coords = count_coords;
+
+	tsfm->config->midpoint = (tsfm->config->extent >> 1) + 1;
+
+	p = kmalloc(2 * count_coords * sizeof(int) * (tsfm->config->extent + 1),
+		    GFP_KERNEL);
+	if (!p) {
+		kfree(tsfm);
+		return NULL;
+	}
+
+	for (n = 0; n < count_coords; n++) {
+		tsfm->sort[n] = p;
+		p += tsfm->config->extent + 1;
+		tsfm->fifo[n] = p;
+		p += tsfm->config->extent + 1;
+	}
+
+	ts_filter_median_clear(&tsfm->tsf);
+
+	dev_info(&pdev->dev,
+		 "Created Median filter len:%d coords:%d dec_threshold:%d\n",
+		 tsfm->config->extent, count_coords,
+		 tsfm->config->decimation_threshold);
+
+	return &tsfm->tsf;
+}
+
+static void ts_filter_median_destroy(struct ts_filter *tsf)
+{
+	struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf);
+
+	kfree(tsfm->sort[0]); /* First guy has pointer from kmalloc. */
+	kfree(tsf);
+}
+
+static void ts_filter_median_scale(struct ts_filter *tsf, int *coords)
+{
+	int n;
+
+	for (n = 0; n < tsf->count_coords; n++)
+		coords[n] = (coords[n] + 2) / 3;
+}
+
+/*
+ * Give us the raw sample data coords, and if we return 1 then you can
+ * get a filtered coordinate from coords. If we return 0 you didn't
+ * fill all the filters with samples yet.
+ */
+
+static int ts_filter_median_process(struct ts_filter *tsf, int *coords)
+{
+	struct ts_filter_median *tsfm = ts_filter_to_filter_median(tsf);
+	int n;
+	int movement = 1;
+
+	for (n = 0; n < tsf->count_coords; n++) {
+		/* Grab copy in insertion order to remove when oldest. */
+		tsfm->fifo[n][tsfm->pos] = coords[n];
+		/* Insert these samples in sorted order in the median arrays. */
+		ts_filter_median_insert(tsfm->sort[n], coords[n], tsfm->valid);
+	}
+	/* Move us on in the fifo. */
+	if (++tsfm->pos == (tsfm->config->extent + 1))
+		tsfm->pos = 0;
+
+	/* Have we finished a median sampling? */
+	if (++tsfm->valid < tsfm->config->extent)
+		goto process_exit; /* No valid sample to use. */
+
+	BUG_ON(tsfm->valid != tsfm->config->extent);
+
+	tsfm->valid--;
+
+	/*
+	 * Sum the middle 3 in the median sorted arrays. We don't divide back
+	 * down which increases the sum resolution by a factor of 3 until the
+	 * scale API function is called.
+	 */
+	for (n = 0; n < tsf->count_coords; n++)
+		/* Perform the deletion of the oldest sample. */
+		ts_filter_median_del(tsfm->sort[n], tsfm->fifo[n][tsfm->pos],
+				     tsfm->valid);
+
+	tsfm->samples_count--;
+	if (tsfm->samples_count >= 0)
+		goto process_exit;
+
+	for (n = 0; n < tsf->count_coords; n++) {
+		/* Give the coordinate result from summing median 3. */
+		coords[n] = tsfm->sort[n][tsfm->config->midpoint - 1] +
+			    tsfm->sort[n][tsfm->config->midpoint] +
+			    tsfm->sort[n][tsfm->config->midpoint + 1];
+
+		movement += abs(tsfm->last_issued[n] - coords[n]);
+	}
+
+	if (movement > tsfm->config->decimation_threshold) /* Moving fast. */
+		tsfm->samples_count = tsfm->config->decimation_above;
+	else
+		tsfm->samples_count = tsfm->config->decimation_below;
+
+	memcpy(&tsfm->last_issued[0], coords, tsf->count_coords * sizeof(int));
+
+	tsfm->ready = 1;
+
+process_exit:
+	return 0;
+}
+
+static int ts_filter_median_haspoint(struct ts_filter *tsf)
+{
+	struct ts_filter_median *priv = ts_filter_to_filter_median(tsf);
+
+	return priv->ready;
+}
+
+static void ts_filter_median_getpoint(struct ts_filter *tsf, int *point)
+{
+	struct ts_filter_median *priv = ts_filter_to_filter_median(tsf);
+
+	BUG_ON(!priv->ready);
+
+	memcpy(point, &priv->last_issued[0], tsf->count_coords * sizeof(int));
+
+	priv->ready = 0;
+}
+
+const struct ts_filter_api ts_filter_median_api = {
+	.create =	ts_filter_median_create,
+	.destroy =	ts_filter_median_destroy,
+	.clear =	ts_filter_median_clear,
+	.process =	ts_filter_median_process,
+	.scale =	ts_filter_median_scale,
+	.haspoint =	ts_filter_median_haspoint,
+	.getpoint =	ts_filter_median_getpoint,
+};
+EXPORT_SYMBOL_GPL(ts_filter_median_api);
+
diff --git a/drivers/input/touchscreen/ts_filter_median.h b/drivers/input/touchscreen/ts_filter_median.h
new file mode 100644
index 00000000000..b13f361bb6a
--- /dev/null
+++ b/drivers/input/touchscreen/ts_filter_median.h
@@ -0,0 +1,32 @@
+#ifndef __TS_FILTER_MEDIAN_H__
+#define __TS_FILTER_MEDIAN_H__
+
+#include "ts_filter.h"
+
+/*
+ * Touchscreen filter.
+ *
+ * median
+ *
+ * (c) 2008 Andy Green <andy@warmcat.com>
+ */
+
+struct ts_filter_median_configuration {
+	/* Size of the filter. */
+	int extent;
+	/* Precomputed midpoint. */
+	int midpoint;
+	/* A reference value for us to check if we are going fast or slow. */
+	int decimation_threshold;
+	/* How many points to replace if we're going fast. */
+	int decimation_above;
+	/* How many points to replace if we're going slow. */
+	int decimation_below;
+
+	/* Generic configuration. */
+	struct ts_filter_configuration config;
+};
+
+extern const struct ts_filter_api ts_filter_median_api;
+
+#endif