spi: add spi_ppc4xx driver

This adds a SPI driver for the SPI controller found in the IBM/AMCC
4xx PowerPC's.

Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Wolfgang Ocker <weo@reccoware.de>
Acked-by: Josh Boyer <jwboyer@linux.vnet.ibm.com>
Signed-off-by: Steven A. Falco <sfalco@harris.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 612 insertions, 0 deletions

diff --git a/drivers/spi/spi_ppc4xx.c b/drivers/spi/spi_ppc4xx.c
new file mode 100644
index 00000000000..140a18d6cf3
--- /dev/null
+++ b/drivers/spi/spi_ppc4xx.c
@@ -0,0 +1,612 @@
+/*
+ * SPI_PPC4XX SPI controller driver.
+ *
+ * Copyright (C) 2007 Gary Jennejohn <garyj@denx.de>
+ * Copyright 2008 Stefan Roese <sr@denx.de>, DENX Software Engineering
+ * Copyright 2009 Harris Corporation, Steven A. Falco <sfalco@harris.com>
+ *
+ * Based in part on drivers/spi/spi_s3c24xx.c
+ *
+ * Copyright (c) 2006 Ben Dooks
+ * Copyright (c) 2006 Simtec Electronics
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * This program is free software; you can redistribute  it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published
+ * by the Free Software Foundation.
+ */
+
+/*
+ * The PPC4xx SPI controller has no FIFO so each sent/received byte will
+ * generate an interrupt to the CPU. This can cause high CPU utilization.
+ * This driver allows platforms to reduce the interrupt load on the CPU
+ * during SPI transfers by setting max_speed_hz via the device tree.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/sched.h>
+#include <linux/errno.h>
+#include <linux/wait.h>
+#include <linux/of_platform.h>
+#include <linux/of_spi.h>
+#include <linux/of_gpio.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+
+#include <linux/gpio.h>
+#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
+
+#include <asm/io.h>
+#include <asm/dcr.h>
+#include <asm/dcr-regs.h>
+
+/* bits in mode register - bit 0 is MSb */
+
+/*
+ * SPI_PPC4XX_MODE_SCP = 0 means "data latched on trailing edge of clock"
+ * SPI_PPC4XX_MODE_SCP = 1 means "data latched on leading edge of clock"
+ * Note: This is the inverse of CPHA.
+ */
+#define SPI_PPC4XX_MODE_SCP	(0x80 >> 3)
+
+/* SPI_PPC4XX_MODE_SPE = 1 means "port enabled" */
+#define SPI_PPC4XX_MODE_SPE	(0x80 >> 4)
+
+/*
+ * SPI_PPC4XX_MODE_RD = 0 means "MSB first" - this is the normal mode
+ * SPI_PPC4XX_MODE_RD = 1 means "LSB first" - this is bit-reversed mode
+ * Note: This is identical to SPI_LSB_FIRST.
+ */
+#define SPI_PPC4XX_MODE_RD	(0x80 >> 5)
+
+/*
+ * SPI_PPC4XX_MODE_CI = 0 means "clock idles low"
+ * SPI_PPC4XX_MODE_CI = 1 means "clock idles high"
+ * Note: This is identical to CPOL.
+ */
+#define SPI_PPC4XX_MODE_CI	(0x80 >> 6)
+
+/*
+ * SPI_PPC4XX_MODE_IL = 0 means "loopback disable"
+ * SPI_PPC4XX_MODE_IL = 1 means "loopback enable"
+ */
+#define SPI_PPC4XX_MODE_IL	(0x80 >> 7)
+
+/* bits in control register */
+/* starts a transfer when set */
+#define SPI_PPC4XX_CR_STR	(0x80 >> 7)
+
+/* bits in status register */
+/* port is busy with a transfer */
+#define SPI_PPC4XX_SR_BSY	(0x80 >> 6)
+/* RxD ready */
+#define SPI_PPC4XX_SR_RBR	(0x80 >> 7)
+
+/* clock settings (SCP and CI) for various SPI modes */
+#define SPI_CLK_MODE0	(SPI_PPC4XX_MODE_SCP | 0)
+#define SPI_CLK_MODE1	(0 | 0)
+#define SPI_CLK_MODE2	(SPI_PPC4XX_MODE_SCP | SPI_PPC4XX_MODE_CI)
+#define SPI_CLK_MODE3	(0 | SPI_PPC4XX_MODE_CI)
+
+#define DRIVER_NAME	"spi_ppc4xx_of"
+
+struct spi_ppc4xx_regs {
+	u8 mode;
+	u8 rxd;
+	u8 txd;
+	u8 cr;
+	u8 sr;
+	u8 dummy;
+	/*
+	 * Clock divisor modulus register
+	 * This uses the follwing formula:
+	 *    SCPClkOut = OPBCLK/(4(CDM + 1))
+	 * or
+	 *    CDM = (OPBCLK/4*SCPClkOut) - 1
+	 * bit 0 is the MSb!
+	 */
+	u8 cdm;
+};
+
+/* SPI Controller driver's private data. */
+struct ppc4xx_spi {
+	/* bitbang has to be first */
+	struct spi_bitbang bitbang;
+	struct completion done;
+
+	u64 mapbase;
+	u64 mapsize;
+	int irqnum;
+	/* need this to set the SPI clock */
+	unsigned int opb_freq;
+
+	/* for transfers */
+	int len;
+	int count;
+	/* data buffers */
+	const unsigned char *tx;
+	unsigned char *rx;
+
+	int *gpios;
+
+	struct spi_ppc4xx_regs __iomem *regs; /* pointer to the registers */
+	struct spi_master *master;
+	struct device *dev;
+};
+
+/* need this so we can set the clock in the chipselect routine */
+struct spi_ppc4xx_cs {
+	u8 mode;
+};
+
+static int spi_ppc4xx_txrx(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ppc4xx_spi *hw;
+	u8 data;
+
+	dev_dbg(&spi->dev, "txrx: tx %p, rx %p, len %d\n",
+		t->tx_buf, t->rx_buf, t->len);
+
+	hw = spi_master_get_devdata(spi->master);
+
+	hw->tx = t->tx_buf;
+	hw->rx = t->rx_buf;
+	hw->len = t->len;
+	hw->count = 0;
+
+	/* send the first byte */
+	data = hw->tx ? hw->tx[0] : 0;
+	out_8(&hw->regs->txd, data);
+	out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
+	wait_for_completion(&hw->done);
+
+	return hw->count;
+}
+
+static int spi_ppc4xx_setupxfer(struct spi_device *spi, struct spi_transfer *t)
+{
+	struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
+	struct spi_ppc4xx_cs *cs = spi->controller_state;
+	int scr;
+	u8 cdm = 0;
+	u32 speed;
+	u8 bits_per_word;
+
+	/* Start with the generic configuration for this device. */
+	bits_per_word = spi->bits_per_word;
+	speed = spi->max_speed_hz;
+
+	/*
+	 * Modify the configuration if the transfer overrides it.  Do not allow
+	 * the transfer to overwrite the generic configuration with zeros.
+	 */
+	if (t) {
+		if (t->bits_per_word)
+			bits_per_word = t->bits_per_word;
+
+		if (t->speed_hz)
+			speed = min(t->speed_hz, spi->max_speed_hz);
+	}
+
+	if (bits_per_word != 8) {
+		dev_err(&spi->dev, "invalid bits-per-word (%d)\n",
+				bits_per_word);
+		return -EINVAL;
+	}
+
+	if (!speed || (speed > spi->max_speed_hz)) {
+		dev_err(&spi->dev, "invalid speed_hz (%d)\n", speed);
+		return -EINVAL;
+	}
+
+	/* Write new configration */
+	out_8(&hw->regs->mode, cs->mode);
+
+	/* Set the clock */
+	/* opb_freq was already divided by 4 */
+	scr = (hw->opb_freq / speed) - 1;
+	if (scr > 0)
+		cdm = min(scr, 0xff);
+
+	dev_dbg(&spi->dev, "setting pre-scaler to %d (hz %d)\n", cdm, speed);
+
+	if (in_8(&hw->regs->cdm) != cdm)
+		out_8(&hw->regs->cdm, cdm);
+
+	spin_lock(&hw->bitbang.lock);
+	if (!hw->bitbang.busy) {
+		hw->bitbang.chipselect(spi, BITBANG_CS_INACTIVE);
+		/* Need to ndelay here? */
+	}
+	spin_unlock(&hw->bitbang.lock);
+
+	return 0;
+}
+
+static int spi_ppc4xx_setup(struct spi_device *spi)
+{
+	struct spi_ppc4xx_cs *cs = spi->controller_state;
+
+	if (spi->bits_per_word != 8) {
+		dev_err(&spi->dev, "invalid bits-per-word (%d)\n",
+			spi->bits_per_word);
+		return -EINVAL;
+	}
+
+	if (!spi->max_speed_hz) {
+		dev_err(&spi->dev, "invalid max_speed_hz (must be non-zero)\n");
+		return -EINVAL;
+	}
+
+	if (cs == NULL) {
+		cs = kzalloc(sizeof *cs, GFP_KERNEL);
+		if (!cs)
+			return -ENOMEM;
+		spi->controller_state = cs;
+	}
+
+	/*
+	 * We set all bits of the SPI0_MODE register, so,
+	 * no need to read-modify-write
+	 */
+	cs->mode = SPI_PPC4XX_MODE_SPE;
+
+	switch (spi->mode & (SPI_CPHA | SPI_CPOL)) {
+	case SPI_MODE_0:
+		cs->mode |= SPI_CLK_MODE0;
+		break;
+	case SPI_MODE_1:
+		cs->mode |= SPI_CLK_MODE1;
+		break;
+	case SPI_MODE_2:
+		cs->mode |= SPI_CLK_MODE2;
+		break;
+	case SPI_MODE_3:
+		cs->mode |= SPI_CLK_MODE3;
+		break;
+	}
+
+	if (spi->mode & SPI_LSB_FIRST)
+		cs->mode |= SPI_PPC4XX_MODE_RD;
+
+	return 0;
+}
+
+static void spi_ppc4xx_chipsel(struct spi_device *spi, int value)
+{
+	struct ppc4xx_spi *hw = spi_master_get_devdata(spi->master);
+	unsigned int cs = spi->chip_select;
+	unsigned int cspol;
+
+	/*
+	 * If there are no chip selects at all, or if this is the special
+	 * case of a non-existent (dummy) chip select, do nothing.
+	 */
+
+	if (!hw->master->num_chipselect || hw->gpios[cs] == -EEXIST)
+		return;
+
+	cspol = spi->mode & SPI_CS_HIGH ? 1 : 0;
+	if (value == BITBANG_CS_INACTIVE)
+		cspol = !cspol;
+
+	gpio_set_value(hw->gpios[cs], cspol);
+}
+
+static irqreturn_t spi_ppc4xx_int(int irq, void *dev_id)
+{
+	struct ppc4xx_spi *hw;
+	u8 status;
+	u8 data;
+	unsigned int count;
+
+	hw = (struct ppc4xx_spi *)dev_id;
+
+	status = in_8(&hw->regs->sr);
+	if (!status)
+		return IRQ_NONE;
+
+	/*
+	 * BSY de-asserts one cycle after the transfer is complete.  The
+	 * interrupt is asserted after the transfer is complete.  The exact
+	 * relationship is not documented, hence this code.
+	 */
+
+	if (unlikely(status & SPI_PPC4XX_SR_BSY)) {
+		u8 lstatus;
+		int cnt = 0;
+
+		dev_dbg(hw->dev, "got interrupt but spi still busy?\n");
+		do {
+			ndelay(10);
+			lstatus = in_8(&hw->regs->sr);
+		} while (++cnt < 100 && lstatus & SPI_PPC4XX_SR_BSY);
+
+		if (cnt >= 100) {
+			dev_err(hw->dev, "busywait: too many loops!\n");
+			complete(&hw->done);
+			return IRQ_HANDLED;
+		} else {
+			/* status is always 1 (RBR) here */
+			status = in_8(&hw->regs->sr);
+			dev_dbg(hw->dev, "loops %d status %x\n", cnt, status);
+		}
+	}
+
+	count = hw->count;
+	hw->count++;
+
+	/* RBR triggered this interrupt.  Therefore, data must be ready. */
+	data = in_8(&hw->regs->rxd);
+	if (hw->rx)
+		hw->rx[count] = data;
+
+	count++;
+
+	if (count < hw->len) {
+		data = hw->tx ? hw->tx[count] : 0;
+		out_8(&hw->regs->txd, data);
+		out_8(&hw->regs->cr, SPI_PPC4XX_CR_STR);
+	} else {
+		complete(&hw->done);
+	}
+
+	return IRQ_HANDLED;
+}
+
+static void spi_ppc4xx_cleanup(struct spi_device *spi)
+{
+	kfree(spi->controller_state);
+}
+
+static void spi_ppc4xx_enable(struct ppc4xx_spi *hw)
+{
+	/*
+	 * On all 4xx PPC's the SPI bus is shared/multiplexed with
+	 * the 2nd I2C bus. We need to enable the the SPI bus before
+	 * using it.
+	 */
+
+	/* need to clear bit 14 to enable SPC */
+	dcri_clrset(SDR0, SDR0_PFC1, 0x80000000 >> 14, 0);
+}
+
+static void free_gpios(struct ppc4xx_spi *hw)
+{
+	if (hw->master->num_chipselect) {
+		int i;
+		for (i = 0; i < hw->master->num_chipselect; i++)
+			if (gpio_is_valid(hw->gpios[i]))
+				gpio_free(hw->gpios[i]);
+
+		kfree(hw->gpios);
+		hw->gpios = NULL;
+	}
+}
+
+/*
+ * of_device layer stuff...
+ */
+static int __init spi_ppc4xx_of_probe(struct of_device *op,
+				      const struct of_device_id *match)
+{
+	struct ppc4xx_spi *hw;
+	struct spi_master *master;
+	struct spi_bitbang *bbp;
+	struct resource resource;
+	struct device_node *np = op->node;
+	struct device *dev = &op->dev;
+	struct device_node *opbnp;
+	int ret;
+	int num_gpios;
+	const unsigned int *clk;
+
+	master = spi_alloc_master(dev, sizeof *hw);
+	if (master == NULL)
+		return -ENOMEM;
+	dev_set_drvdata(dev, master);
+	hw = spi_master_get_devdata(master);
+	hw->master = spi_master_get(master);
+	hw->dev = dev;
+
+	init_completion(&hw->done);
+
+	/*
+	 * A count of zero implies a single SPI device without any chip-select.
+	 * Note that of_gpio_count counts all gpios assigned to this spi master.
+	 * This includes both "null" gpio's and real ones.
+	 */
+	num_gpios = of_gpio_count(np);
+	if (num_gpios) {
+		int i;
+
+		hw->gpios = kzalloc(sizeof(int) * num_gpios, GFP_KERNEL);
+		if (!hw->gpios) {
+			ret = -ENOMEM;
+			goto free_master;
+		}
+
+		for (i = 0; i < num_gpios; i++) {
+			int gpio;
+			enum of_gpio_flags flags;
+
+			gpio = of_get_gpio_flags(np, i, &flags);
+			hw->gpios[i] = gpio;
+
+			if (gpio_is_valid(gpio)) {
+				/* Real CS - set the initial state. */
+				ret = gpio_request(gpio, np->name);
+				if (ret < 0) {
+					dev_err(dev, "can't request gpio "
+							"#%d: %d\n", i, ret);
+					goto free_gpios;
+				}
+
+				gpio_direction_output(gpio,
+						!!(flags & OF_GPIO_ACTIVE_LOW));
+			} else if (gpio == -EEXIST) {
+				; /* No CS, but that's OK. */
+			} else {
+				dev_err(dev, "invalid gpio #%d: %d\n", i, gpio);
+				ret = -EINVAL;
+				goto free_gpios;
+			}
+		}
+	}
+
+	/* Setup the state for the bitbang driver */
+	bbp = &hw->bitbang;
+	bbp->master = hw->master;
+	bbp->setup_transfer = spi_ppc4xx_setupxfer;
+	bbp->chipselect = spi_ppc4xx_chipsel;
+	bbp->txrx_bufs = spi_ppc4xx_txrx;
+	bbp->use_dma = 0;
+	bbp->master->setup = spi_ppc4xx_setup;
+	bbp->master->cleanup = spi_ppc4xx_cleanup;
+
+	/* Allocate bus num dynamically. */
+	bbp->master->bus_num = -1;
+
+	/* the spi->mode bits understood by this driver: */
+	bbp->master->mode_bits =
+		SPI_CPHA | SPI_CPOL | SPI_CS_HIGH | SPI_LSB_FIRST;
+
+	/* this many pins in all GPIO controllers */
+	bbp->master->num_chipselect = num_gpios;
+
+	/* Get the clock for the OPB */
+	opbnp = of_find_compatible_node(NULL, NULL, "ibm,opb");
+	if (opbnp == NULL) {
+		dev_err(dev, "OPB: cannot find node\n");
+		ret = -ENODEV;
+		goto free_gpios;
+	}
+	/* Get the clock (Hz) for the OPB */
+	clk = of_get_property(opbnp, "clock-frequency", NULL);
+	if (clk == NULL) {
+		dev_err(dev, "OPB: no clock-frequency property set\n");
+		of_node_put(opbnp);
+		ret = -ENODEV;
+		goto free_gpios;
+	}
+	hw->opb_freq = *clk;
+	hw->opb_freq >>= 2;
+	of_node_put(opbnp);
+
+	ret = of_address_to_resource(np, 0, &resource);
+	if (ret) {
+		dev_err(dev, "error while parsing device node resource\n");
+		goto free_gpios;
+	}
+	hw->mapbase = resource.start;
+	hw->mapsize = resource.end - resource.start + 1;
+
+	/* Sanity check */
+	if (hw->mapsize < sizeof(struct spi_ppc4xx_regs)) {
+		dev_err(dev, "too small to map registers\n");
+		ret = -EINVAL;
+		goto free_gpios;
+	}
+
+	/* Request IRQ */
+	hw->irqnum = irq_of_parse_and_map(np, 0);
+	ret = request_irq(hw->irqnum, spi_ppc4xx_int,
+			  IRQF_DISABLED, "spi_ppc4xx_of", (void *)hw);
+	if (ret) {
+		dev_err(dev, "unable to allocate interrupt\n");
+		goto free_gpios;
+	}
+
+	if (!request_mem_region(hw->mapbase, hw->mapsize, DRIVER_NAME)) {
+		dev_err(dev, "resource unavailable\n");
+		ret = -EBUSY;
+		goto request_mem_error;
+	}
+
+	hw->regs = ioremap(hw->mapbase, sizeof(struct spi_ppc4xx_regs));
+
+	if (!hw->regs) {
+		dev_err(dev, "unable to memory map registers\n");
+		ret = -ENXIO;
+		goto map_io_error;
+	}
+
+	spi_ppc4xx_enable(hw);
+
+	/* Finally register our spi controller */
+	dev->dma_mask = 0;
+	ret = spi_bitbang_start(bbp);
+	if (ret) {
+		dev_err(dev, "failed to register SPI master\n");
+		goto unmap_regs;
+	}
+
+	dev_info(dev, "driver initialized\n");
+	of_register_spi_devices(master, np);
+
+	return 0;
+
+unmap_regs:
+	iounmap(hw->regs);
+map_io_error:
+	release_mem_region(hw->mapbase, hw->mapsize);
+request_mem_error:
+	free_irq(hw->irqnum, hw);
+free_gpios:
+	free_gpios(hw);
+free_master:
+	dev_set_drvdata(dev, NULL);
+	spi_master_put(master);
+
+	dev_err(dev, "initialization failed\n");
+	return ret;
+}
+
+static int __exit spi_ppc4xx_of_remove(struct of_device *op)
+{
+	struct spi_master *master = dev_get_drvdata(&op->dev);
+	struct ppc4xx_spi *hw = spi_master_get_devdata(master);
+
+	spi_bitbang_stop(&hw->bitbang);
+	dev_set_drvdata(&op->dev, NULL);
+	release_mem_region(hw->mapbase, hw->mapsize);
+	free_irq(hw->irqnum, hw);
+	iounmap(hw->regs);
+	free_gpios(hw);
+	return 0;
+}
+
+static struct of_device_id spi_ppc4xx_of_match[] = {
+	{ .compatible = "ibm,ppc4xx-spi", },
+	{},
+};
+
+MODULE_DEVICE_TABLE(of, spi_ppc4xx_of_match);
+
+static struct of_platform_driver spi_ppc4xx_of_driver = {
+	.match_table = spi_ppc4xx_of_match,
+	.probe = spi_ppc4xx_of_probe,
+	.remove = __exit_p(spi_ppc4xx_of_remove),
+	.driver = {
+		.name = DRIVER_NAME,
+		.owner = THIS_MODULE,
+	},
+};
+
+static int __init spi_ppc4xx_init(void)
+{
+	return of_register_platform_driver(&spi_ppc4xx_of_driver);
+}
+module_init(spi_ppc4xx_init);
+
+static void __exit spi_ppc4xx_exit(void)
+{
+	of_unregister_platform_driver(&spi_ppc4xx_of_driver);
+}
+module_exit(spi_ppc4xx_exit);
+
+MODULE_AUTHOR("Gary Jennejohn & Stefan Roese");
+MODULE_DESCRIPTION("Simple PPC4xx SPI Driver");
+MODULE_LICENSE("GPL");