aboutsummaryrefslogtreecommitdiff
path: root/drivers/w1/masters/mxc_w1.c
blob: 12c1ab844d800e310b3121d49ddb50363dd76c02 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
/*
 * 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/slab.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 __devinit 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, NULL);
	if (IS_ERR(mdev->clk)) {
		err = PTR_ERR(mdev->clk);
		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_prepare_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 __devexit 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_unprepare(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");