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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 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");
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