1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2005 Simtec Electronics
4 * Ben Dooks <ben@simtec.co.uk>
5 *
6 * Simtec Generic I2C Controller
7 */
8
9 #include <linux/kernel.h>
10 #include <linux/module.h>
11 #include <linux/delay.h>
12 #include <linux/platform_device.h>
13 #include <linux/slab.h>
14 #include <linux/io.h>
15
16 #include <linux/i2c.h>
17 #include <linux/i2c-algo-bit.h>
18
19 struct simtec_i2c_data {
20 struct resource *ioarea;
21 void __iomem *reg;
22 struct i2c_adapter adap;
23 struct i2c_algo_bit_data bit;
24 };
25
26 #define CMD_SET_SDA (1<<2)
27 #define CMD_SET_SCL (1<<3)
28
29 #define STATE_SDA (1<<0)
30 #define STATE_SCL (1<<1)
31
32 /* i2c bit-bus functions */
33
simtec_i2c_setsda(void * pw,int state)34 static void simtec_i2c_setsda(void *pw, int state)
35 {
36 struct simtec_i2c_data *pd = pw;
37 writeb(CMD_SET_SDA | (state ? STATE_SDA : 0), pd->reg);
38 }
39
simtec_i2c_setscl(void * pw,int state)40 static void simtec_i2c_setscl(void *pw, int state)
41 {
42 struct simtec_i2c_data *pd = pw;
43 writeb(CMD_SET_SCL | (state ? STATE_SCL : 0), pd->reg);
44 }
45
simtec_i2c_getsda(void * pw)46 static int simtec_i2c_getsda(void *pw)
47 {
48 struct simtec_i2c_data *pd = pw;
49 return readb(pd->reg) & STATE_SDA ? 1 : 0;
50 }
51
simtec_i2c_getscl(void * pw)52 static int simtec_i2c_getscl(void *pw)
53 {
54 struct simtec_i2c_data *pd = pw;
55 return readb(pd->reg) & STATE_SCL ? 1 : 0;
56 }
57
58 /* device registration */
59
simtec_i2c_probe(struct platform_device * dev)60 static int simtec_i2c_probe(struct platform_device *dev)
61 {
62 struct simtec_i2c_data *pd;
63 struct resource *res;
64 int size;
65 int ret;
66
67 pd = kzalloc(sizeof(struct simtec_i2c_data), GFP_KERNEL);
68 if (pd == NULL)
69 return -ENOMEM;
70
71 platform_set_drvdata(dev, pd);
72
73 res = platform_get_resource(dev, IORESOURCE_MEM, 0);
74 if (res == NULL) {
75 dev_err(&dev->dev, "cannot find IO resource\n");
76 ret = -ENOENT;
77 goto err;
78 }
79
80 size = resource_size(res);
81
82 pd->ioarea = request_mem_region(res->start, size, dev->name);
83 if (pd->ioarea == NULL) {
84 dev_err(&dev->dev, "cannot request IO\n");
85 ret = -ENXIO;
86 goto err;
87 }
88
89 pd->reg = ioremap(res->start, size);
90 if (pd->reg == NULL) {
91 dev_err(&dev->dev, "cannot map IO\n");
92 ret = -ENXIO;
93 goto err_res;
94 }
95
96 /* setup the private data */
97
98 pd->adap.owner = THIS_MODULE;
99 pd->adap.algo_data = &pd->bit;
100 pd->adap.dev.parent = &dev->dev;
101
102 strscpy(pd->adap.name, "Simtec I2C", sizeof(pd->adap.name));
103
104 pd->bit.data = pd;
105 pd->bit.setsda = simtec_i2c_setsda;
106 pd->bit.setscl = simtec_i2c_setscl;
107 pd->bit.getsda = simtec_i2c_getsda;
108 pd->bit.getscl = simtec_i2c_getscl;
109 pd->bit.timeout = HZ;
110 pd->bit.udelay = 20;
111
112 ret = i2c_bit_add_bus(&pd->adap);
113 if (ret)
114 goto err_all;
115
116 return 0;
117
118 err_all:
119 iounmap(pd->reg);
120
121 err_res:
122 release_mem_region(pd->ioarea->start, size);
123
124 err:
125 kfree(pd);
126 return ret;
127 }
128
simtec_i2c_remove(struct platform_device * dev)129 static void simtec_i2c_remove(struct platform_device *dev)
130 {
131 struct simtec_i2c_data *pd = platform_get_drvdata(dev);
132
133 i2c_del_adapter(&pd->adap);
134
135 iounmap(pd->reg);
136 release_mem_region(pd->ioarea->start, resource_size(pd->ioarea));
137 kfree(pd);
138 }
139
140 /* device driver */
141
142 static struct platform_driver simtec_i2c_driver = {
143 .driver = {
144 .name = "simtec-i2c",
145 },
146 .probe = simtec_i2c_probe,
147 .remove_new = simtec_i2c_remove,
148 };
149
150 module_platform_driver(simtec_i2c_driver);
151
152 MODULE_DESCRIPTION("Simtec Generic I2C Bus driver");
153 MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
154 MODULE_LICENSE("GPL");
155 MODULE_ALIAS("platform:simtec-i2c");
156