1 /*
2 * Copyright 2005-2008 Freescale Semiconductor, Inc. All Rights Reserved.
3 * Copyright 2008 Luotao Fu, kernel@pengutronix.de
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version 2
8 * of the License, or (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
17 *
18 */
19
20 #include <linux/module.h>
21 #include <linux/interrupt.h>
22 #include <linux/platform_device.h>
23 #include <linux/clk.h>
24 #include <linux/delay.h>
25 #include <linux/io.h>
26
27 #include "../w1.h"
28 #include "../w1_int.h"
29 #include "../w1_log.h"
30
31 /* According to the mx27 Datasheet the reset procedure should take up to about
32 * 1350us. We set the timeout to 500*100us = 50ms for sure */
33 #define MXC_W1_RESET_TIMEOUT 500
34
35 /*
36 * MXC W1 Register offsets
37 */
38 #define MXC_W1_CONTROL 0x00
39 #define MXC_W1_TIME_DIVIDER 0x02
40 #define MXC_W1_RESET 0x04
41 #define MXC_W1_COMMAND 0x06
42 #define MXC_W1_TXRX 0x08
43 #define MXC_W1_INTERRUPT 0x0A
44 #define MXC_W1_INTERRUPT_EN 0x0C
45
46 struct mxc_w1_device {
47 void __iomem *regs;
48 unsigned int clkdiv;
49 struct clk *clk;
50 struct w1_bus_master bus_master;
51 };
52
53 /*
54 * this is the low level routine to
55 * reset the device on the One Wire interface
56 * on the hardware
57 */
mxc_w1_ds2_reset_bus(void * data)58 static u8 mxc_w1_ds2_reset_bus(void *data)
59 {
60 u8 reg_val;
61 unsigned int timeout_cnt = 0;
62 struct mxc_w1_device *dev = data;
63
64 __raw_writeb(0x80, (dev->regs + MXC_W1_CONTROL));
65
66 while (1) {
67 reg_val = __raw_readb(dev->regs + MXC_W1_CONTROL);
68
69 if (((reg_val >> 7) & 0x1) == 0 ||
70 timeout_cnt > MXC_W1_RESET_TIMEOUT)
71 break;
72 else
73 timeout_cnt++;
74
75 udelay(100);
76 }
77 return (reg_val >> 7) & 0x1;
78 }
79
80 /*
81 * this is the low level routine to read/write a bit on the One Wire
82 * interface on the hardware. It does write 0 if parameter bit is set
83 * to 0, otherwise a write 1/read.
84 */
mxc_w1_ds2_touch_bit(void * data,u8 bit)85 static u8 mxc_w1_ds2_touch_bit(void *data, u8 bit)
86 {
87 struct mxc_w1_device *mdev = data;
88 void __iomem *ctrl_addr = mdev->regs + MXC_W1_CONTROL;
89 unsigned int timeout_cnt = 400; /* Takes max. 120us according to
90 * datasheet.
91 */
92
93 __raw_writeb((1 << (5 - bit)), ctrl_addr);
94
95 while (timeout_cnt--) {
96 if (!((__raw_readb(ctrl_addr) >> (5 - bit)) & 0x1))
97 break;
98
99 udelay(1);
100 }
101
102 return ((__raw_readb(ctrl_addr)) >> 3) & 0x1;
103 }
104
mxc_w1_probe(struct platform_device * pdev)105 static int __init mxc_w1_probe(struct platform_device *pdev)
106 {
107 struct mxc_w1_device *mdev;
108 struct resource *res;
109 int err = 0;
110
111 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
112 if (!res)
113 return -ENODEV;
114
115 mdev = kzalloc(sizeof(struct mxc_w1_device), GFP_KERNEL);
116 if (!mdev)
117 return -ENOMEM;
118
119 mdev->clk = clk_get(&pdev->dev, "owire_clk");
120 if (!mdev->clk) {
121 err = -ENODEV;
122 goto failed_clk;
123 }
124
125 mdev->clkdiv = (clk_get_rate(mdev->clk) / 1000000) - 1;
126
127 res = request_mem_region(res->start, resource_size(res),
128 "mxc_w1");
129 if (!res) {
130 err = -EBUSY;
131 goto failed_req;
132 }
133
134 mdev->regs = ioremap(res->start, resource_size(res));
135 if (!mdev->regs) {
136 printk(KERN_ERR "Cannot map frame buffer registers\n");
137 goto failed_ioremap;
138 }
139
140 clk_enable(mdev->clk);
141 __raw_writeb(mdev->clkdiv, mdev->regs + MXC_W1_TIME_DIVIDER);
142
143 mdev->bus_master.data = mdev;
144 mdev->bus_master.reset_bus = mxc_w1_ds2_reset_bus;
145 mdev->bus_master.touch_bit = mxc_w1_ds2_touch_bit;
146
147 err = w1_add_master_device(&mdev->bus_master);
148
149 if (err)
150 goto failed_add;
151
152 platform_set_drvdata(pdev, mdev);
153 return 0;
154
155 failed_add:
156 iounmap(mdev->regs);
157 failed_ioremap:
158 release_mem_region(res->start, resource_size(res));
159 failed_req:
160 clk_put(mdev->clk);
161 failed_clk:
162 kfree(mdev);
163 return err;
164 }
165
166 /*
167 * disassociate the w1 device from the driver
168 */
mxc_w1_remove(struct platform_device * pdev)169 static int mxc_w1_remove(struct platform_device *pdev)
170 {
171 struct mxc_w1_device *mdev = platform_get_drvdata(pdev);
172 struct resource *res;
173
174 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
175
176 w1_remove_master_device(&mdev->bus_master);
177
178 iounmap(mdev->regs);
179 release_mem_region(res->start, resource_size(res));
180 clk_disable(mdev->clk);
181 clk_put(mdev->clk);
182
183 platform_set_drvdata(pdev, NULL);
184
185 return 0;
186 }
187
188 static struct platform_driver mxc_w1_driver = {
189 .driver = {
190 .name = "mxc_w1",
191 },
192 .probe = mxc_w1_probe,
193 .remove = mxc_w1_remove,
194 };
195
mxc_w1_init(void)196 static int __init mxc_w1_init(void)
197 {
198 return platform_driver_register(&mxc_w1_driver);
199 }
200
mxc_w1_exit(void)201 static void mxc_w1_exit(void)
202 {
203 platform_driver_unregister(&mxc_w1_driver);
204 }
205
206 module_init(mxc_w1_init);
207 module_exit(mxc_w1_exit);
208
209 MODULE_LICENSE("GPL");
210 MODULE_AUTHOR("Freescale Semiconductors Inc");
211 MODULE_DESCRIPTION("Driver for One-Wire on MXC");
212