This source file includes following definitions.
- cbus_send_bit
- cbus_send_data
- cbus_receive_bit
- cbus_receive_word
- cbus_transfer
- cbus_i2c_smbus_xfer
- cbus_i2c_func
- cbus_i2c_remove
- cbus_i2c_probe
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19 #include <linux/io.h>
20 #include <linux/i2c.h>
21 #include <linux/slab.h>
22 #include <linux/delay.h>
23 #include <linux/errno.h>
24 #include <linux/kernel.h>
25 #include <linux/module.h>
26 #include <linux/gpio/consumer.h>
27 #include <linux/interrupt.h>
28 #include <linux/platform_device.h>
29
30
31
32
33
34 #define CBUS_ADDR_BITS 3
35 #define CBUS_REG_BITS 5
36
37 struct cbus_host {
38 spinlock_t lock;
39 struct device *dev;
40 struct gpio_desc *clk;
41 struct gpio_desc *dat;
42 struct gpio_desc *sel;
43 };
44
45
46
47
48
49
50 static void cbus_send_bit(struct cbus_host *host, unsigned bit)
51 {
52 gpiod_set_value(host->dat, bit ? 1 : 0);
53 gpiod_set_value(host->clk, 1);
54 gpiod_set_value(host->clk, 0);
55 }
56
57
58
59
60
61
62
63 static void cbus_send_data(struct cbus_host *host, unsigned data, unsigned len)
64 {
65 int i;
66
67 for (i = len; i > 0; i--)
68 cbus_send_bit(host, data & (1 << (i - 1)));
69 }
70
71
72
73
74
75 static int cbus_receive_bit(struct cbus_host *host)
76 {
77 int ret;
78
79 gpiod_set_value(host->clk, 1);
80 ret = gpiod_get_value(host->dat);
81 gpiod_set_value(host->clk, 0);
82 return ret;
83 }
84
85
86
87
88
89 static int cbus_receive_word(struct cbus_host *host)
90 {
91 int ret = 0;
92 int i;
93
94 for (i = 16; i > 0; i--) {
95 int bit = cbus_receive_bit(host);
96
97 if (bit < 0)
98 return bit;
99
100 if (bit)
101 ret |= 1 << (i - 1);
102 }
103 return ret;
104 }
105
106
107
108
109
110
111
112
113
114 static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev,
115 unsigned reg, unsigned data)
116 {
117 unsigned long flags;
118 int ret;
119
120
121 spin_lock_irqsave(&host->lock, flags);
122
123
124 gpiod_set_value(host->sel, 0);
125
126
127 gpiod_direction_output(host->dat, 1);
128
129
130 cbus_send_data(host, dev, CBUS_ADDR_BITS);
131
132
133 cbus_send_bit(host, rw == I2C_SMBUS_READ);
134
135
136 cbus_send_data(host, reg, CBUS_REG_BITS);
137
138 if (rw == I2C_SMBUS_WRITE) {
139 cbus_send_data(host, data, 16);
140 ret = 0;
141 } else {
142 ret = gpiod_direction_input(host->dat);
143 if (ret) {
144 dev_dbg(host->dev, "failed setting direction\n");
145 goto out;
146 }
147 gpiod_set_value(host->clk, 1);
148
149 ret = cbus_receive_word(host);
150 if (ret < 0) {
151 dev_dbg(host->dev, "failed receiving data\n");
152 goto out;
153 }
154 }
155
156
157 gpiod_set_value(host->sel, 1);
158 gpiod_set_value(host->clk, 1);
159 gpiod_set_value(host->clk, 0);
160
161 out:
162 spin_unlock_irqrestore(&host->lock, flags);
163
164 return ret;
165 }
166
167 static int cbus_i2c_smbus_xfer(struct i2c_adapter *adapter,
168 u16 addr,
169 unsigned short flags,
170 char read_write,
171 u8 command,
172 int size,
173 union i2c_smbus_data *data)
174 {
175 struct cbus_host *chost = i2c_get_adapdata(adapter);
176 int ret;
177
178 if (size != I2C_SMBUS_WORD_DATA)
179 return -EINVAL;
180
181 ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr,
182 command, data->word);
183 if (ret < 0)
184 return ret;
185
186 if (read_write == I2C_SMBUS_READ)
187 data->word = ret;
188
189 return 0;
190 }
191
192 static u32 cbus_i2c_func(struct i2c_adapter *adapter)
193 {
194 return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA;
195 }
196
197 static const struct i2c_algorithm cbus_i2c_algo = {
198 .smbus_xfer = cbus_i2c_smbus_xfer,
199 .functionality = cbus_i2c_func,
200 };
201
202 static int cbus_i2c_remove(struct platform_device *pdev)
203 {
204 struct i2c_adapter *adapter = platform_get_drvdata(pdev);
205
206 i2c_del_adapter(adapter);
207
208 return 0;
209 }
210
211 static int cbus_i2c_probe(struct platform_device *pdev)
212 {
213 struct i2c_adapter *adapter;
214 struct cbus_host *chost;
215
216 adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter),
217 GFP_KERNEL);
218 if (!adapter)
219 return -ENOMEM;
220
221 chost = devm_kzalloc(&pdev->dev, sizeof(*chost), GFP_KERNEL);
222 if (!chost)
223 return -ENOMEM;
224
225 if (gpiod_count(&pdev->dev, NULL) != 3)
226 return -ENODEV;
227 chost->clk = devm_gpiod_get_index(&pdev->dev, NULL, 0, GPIOD_OUT_LOW);
228 if (IS_ERR(chost->clk))
229 return PTR_ERR(chost->clk);
230 chost->dat = devm_gpiod_get_index(&pdev->dev, NULL, 1, GPIOD_IN);
231 if (IS_ERR(chost->dat))
232 return PTR_ERR(chost->dat);
233 chost->sel = devm_gpiod_get_index(&pdev->dev, NULL, 2, GPIOD_OUT_HIGH);
234 if (IS_ERR(chost->sel))
235 return PTR_ERR(chost->sel);
236 gpiod_set_consumer_name(chost->clk, "CBUS clk");
237 gpiod_set_consumer_name(chost->dat, "CBUS dat");
238 gpiod_set_consumer_name(chost->sel, "CBUS sel");
239
240 adapter->owner = THIS_MODULE;
241 adapter->class = I2C_CLASS_HWMON;
242 adapter->dev.parent = &pdev->dev;
243 adapter->dev.of_node = pdev->dev.of_node;
244 adapter->nr = pdev->id;
245 adapter->timeout = HZ;
246 adapter->algo = &cbus_i2c_algo;
247 strlcpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name));
248
249 spin_lock_init(&chost->lock);
250 chost->dev = &pdev->dev;
251
252 i2c_set_adapdata(adapter, chost);
253 platform_set_drvdata(pdev, adapter);
254
255 return i2c_add_numbered_adapter(adapter);
256 }
257
258 #if defined(CONFIG_OF)
259 static const struct of_device_id i2c_cbus_dt_ids[] = {
260 { .compatible = "i2c-cbus-gpio", },
261 { }
262 };
263 MODULE_DEVICE_TABLE(of, i2c_cbus_dt_ids);
264 #endif
265
266 static struct platform_driver cbus_i2c_driver = {
267 .probe = cbus_i2c_probe,
268 .remove = cbus_i2c_remove,
269 .driver = {
270 .name = "i2c-cbus-gpio",
271 .of_match_table = of_match_ptr(i2c_cbus_dt_ids),
272 },
273 };
274 module_platform_driver(cbus_i2c_driver);
275
276 MODULE_ALIAS("platform:i2c-cbus-gpio");
277 MODULE_DESCRIPTION("CBUS I2C driver");
278 MODULE_AUTHOR("Juha Yrjölä");
279 MODULE_AUTHOR("David Weinehall");
280 MODULE_AUTHOR("Mikko Ylinen");
281 MODULE_AUTHOR("Felipe Balbi");
282 MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>");
283 MODULE_LICENSE("GPL");