w1: add 1-wire master driver for i.MX27 / i.MX31 (a5fd9139) · Commits · 戴 / test

Documentation/w1/masters/00-INDEX

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		@@ -4,5 +4,7 @@ ds2482
		- The Maxim/Dallas Semiconductor DS2482 provides 1-wire busses.
		ds2490
		- The Maxim/Dallas Semiconductor DS2490 builds USB <-> W1 bridges.
		mxc_w1
		- W1 master controller driver found on Freescale MX2/MX3 SoCs
		w1-gpio
		- GPIO 1-wire bus master driver.

Documentation/w1/masters/mxc-w1

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		Kernel driver mxc_w1
		====================

		Supported chips:
		* Freescale MX27, MX31 and probably other i.MX SoCs
		Datasheets:
		http://www.freescale.com/files/32bit/doc/data_sheet/MCIMX31.pdf?fpsp=1
		http://www.freescale.com/files/dsp/MCIMX27.pdf?fpsp=1

		Author: Originally based on Freescale code, prepared for mainline by
		Sascha Hauer <s.hauer@pengutronix.de>

drivers/w1/masters/Kconfig

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		@@ -34,6 +34,12 @@ config W1_MASTER_DS2482
		This driver can also be built as a module. If so, the module
		will be called ds2482.

		config W1_MASTER_MXC
		tristate "Freescale MXC 1-wire busmaster"
		depends on W1 && ARCH_MXC
		help
		Say Y here to enable MXC 1-wire host

		config W1_MASTER_DS1WM
		tristate "Maxim DS1WM 1-wire busmaster"
		depends on W1 && ARM && HAVE_CLK

drivers/w1/masters/Makefile

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		@@ -5,6 +5,8 @@
		obj-$(CONFIG_W1_MASTER_MATROX) += matrox_w1.o
		obj-$(CONFIG_W1_MASTER_DS2490) += ds2490.o
		obj-$(CONFIG_W1_MASTER_DS2482) += ds2482.o
		obj-$(CONFIG_W1_MASTER_MXC) += mxc_w1.o

		obj-$(CONFIG_W1_MASTER_DS1WM) += ds1wm.o
		obj-$(CONFIG_W1_MASTER_GPIO) += w1-gpio.o
		obj-$(CONFIG_HDQ_MASTER_OMAP) += omap_hdq.o

drivers/w1/masters/mxc_w1.c

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		/*
		* 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 500100us = 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");

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