diff options
Diffstat (limited to 'drivers/w1/masters/mxc_w1.c')
| -rw-r--r-- | drivers/w1/masters/mxc_w1.c | 211 |
1 files changed, 211 insertions, 0 deletions
diff --git a/drivers/w1/masters/mxc_w1.c b/drivers/w1/masters/mxc_w1.c new file mode 100644 index 00000000000..b9d74d0b353 --- /dev/null +++ b/drivers/w1/masters/mxc_w1.c @@ -0,0 +1,211 @@ +/* + * Copyright 2005-2008 Freescale Semiconductor, Inc. All Rights Reserved. + * Copyright 2008 Luotao Fu, kernel@pengutronix.de + * + * 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + */ + +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/platform_device.h> +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/io.h> + +#include "../w1.h" +#include "../w1_int.h" +#include "../w1_log.h" + +/* According to the mx27 Datasheet the reset procedure should take up to about + * 1350us. We set the timeout to 500*100us = 50ms for sure */ +#define MXC_W1_RESET_TIMEOUT 500 + +/* + * MXC W1 Register offsets + */ +#define MXC_W1_CONTROL 0x00 +#define MXC_W1_TIME_DIVIDER 0x02 +#define MXC_W1_RESET 0x04 +#define MXC_W1_COMMAND 0x06 +#define MXC_W1_TXRX 0x08 +#define MXC_W1_INTERRUPT 0x0A +#define MXC_W1_INTERRUPT_EN 0x0C + +struct mxc_w1_device { + void __iomem *regs; + unsigned int clkdiv; + struct clk *clk; + struct w1_bus_master bus_master; +}; + +/* + * this is the low level routine to + * reset the device on the One Wire interface + * on the hardware + */ +static u8 mxc_w1_ds2_reset_bus(void *data) +{ + u8 reg_val; + unsigned int timeout_cnt = 0; + struct mxc_w1_device *dev = data; + + __raw_writeb(0x80, (dev->regs + MXC_W1_CONTROL)); + + while (1) { + reg_val = __raw_readb(dev->regs + MXC_W1_CONTROL); + + if (((reg_val >> 7) & 0x1) == 0 || + timeout_cnt > MXC_W1_RESET_TIMEOUT) + break; + else + timeout_cnt++; + + udelay(100); + } + return (reg_val >> 7) & 0x1; +} + +/* + * this is the low level routine to read/write a bit on the One Wire + * interface on the hardware. It does write 0 if parameter bit is set + * to 0, otherwise a write 1/read. + */ +static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit) +{ + struct mxc_w1_device *mdev = data; + void __iomem *ctrl_addr = mdev->regs + MXC_W1_CONTROL; + unsigned int timeout_cnt = 400; /* Takes max. 120us according to + * datasheet. + */ + + __raw_writeb((1 << (5 - bit)), ctrl_addr); + + while (timeout_cnt--) { + if (!((__raw_readb(ctrl_addr) >> (5 - bit)) & 0x1)) + break; + + udelay(1); + } + + return ((__raw_readb(ctrl_addr)) >> 3) & 0x1; +} + +static int __init mxc_w1_probe(struct platform_device *pdev) +{ + struct mxc_w1_device *mdev; + struct resource *res; + int err = 0; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (!res) + return -ENODEV; + + mdev = kzalloc(sizeof(struct mxc_w1_device), GFP_KERNEL); + if (!mdev) + return -ENOMEM; + + mdev->clk = clk_get(&pdev->dev, "owire_clk"); + if (!mdev->clk) { + err = -ENODEV; + goto failed_clk; + } + + mdev->clkdiv = (clk_get_rate(mdev->clk) / 1000000) - 1; + + res = request_mem_region(res->start, resource_size(res), + "mxc_w1"); + if (!res) { + err = -EBUSY; + goto failed_req; + } + + mdev->regs = ioremap(res->start, resource_size(res)); + if (!mdev->regs) { + printk(KERN_ERR "Cannot map frame buffer registers\n"); + goto failed_ioremap; + } + + clk_enable(mdev->clk); + __raw_writeb(mdev->clkdiv, mdev->regs + MXC_W1_TIME_DIVIDER); + + mdev->bus_master.data = mdev; + mdev->bus_master.reset_bus = mxc_w1_ds2_reset_bus; + mdev->bus_master.touch_bit = mxc_w1_ds2_touch_bit; + + err = w1_add_master_device(&mdev->bus_master); + + if (err) + goto failed_add; + + platform_set_drvdata(pdev, mdev); + return 0; + +failed_add: + iounmap(mdev->regs); +failed_ioremap: + release_mem_region(res->start, resource_size(res)); +failed_req: + clk_put(mdev->clk); +failed_clk: + kfree(mdev); + return err; +} + +/* + * disassociate the w1 device from the driver + */ +static int mxc_w1_remove(struct platform_device *pdev) +{ + struct mxc_w1_device *mdev = platform_get_drvdata(pdev); + struct resource *res; + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + + w1_remove_master_device(&mdev->bus_master); + + iounmap(mdev->regs); + release_mem_region(res->start, resource_size(res)); + clk_disable(mdev->clk); + clk_put(mdev->clk); + + platform_set_drvdata(pdev, NULL); + + return 0; +} + +static struct platform_driver mxc_w1_driver = { + .driver = { + .name = "mxc_w1", + }, + .probe = mxc_w1_probe, + .remove = mxc_w1_remove, +}; + +static int __init mxc_w1_init(void) +{ + return platform_driver_register(&mxc_w1_driver); +} + +static void mxc_w1_exit(void) +{ + platform_driver_unregister(&mxc_w1_driver); +} + +module_init(mxc_w1_init); +module_exit(mxc_w1_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Freescale Semiconductors Inc"); +MODULE_DESCRIPTION("Driver for One-Wire on MXC"); |