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0857ba3c AK |
1 | /* |
2 | * CBUS I2C driver for Nokia Internet Tablets. | |
3 | * | |
4 | * Copyright (C) 2004-2010 Nokia Corporation | |
5 | * | |
6 | * Based on code written by Juha Yrjölä, David Weinehall, Mikko Ylinen and | |
7 | * Felipe Balbi. Converted to I2C driver by Aaro Koskinen. | |
8 | * | |
9 | * This file is subject to the terms and conditions of the GNU General | |
10 | * Public License. See the file "COPYING" in the main directory of this | |
11 | * archive for more details. | |
12 | * | |
13 | * This program is distributed in the hope that it will be useful, | |
14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
16 | * GNU General Public License for more details. | |
17 | */ | |
18 | ||
19 | #include <linux/io.h> | |
20 | #include <linux/i2c.h> | |
21 | #include <linux/gpio.h> | |
0857ba3c AK |
22 | #include <linux/slab.h> |
23 | #include <linux/delay.h> | |
24 | #include <linux/errno.h> | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/module.h> | |
27 | #include <linux/of_gpio.h> | |
28 | #include <linux/interrupt.h> | |
29 | #include <linux/platform_device.h> | |
30 | #include <linux/platform_data/i2c-cbus-gpio.h> | |
31 | ||
32 | /* | |
33 | * Bit counts are derived from Nokia implementation. These should be checked | |
34 | * if other CBUS implementations appear. | |
35 | */ | |
36 | #define CBUS_ADDR_BITS 3 | |
37 | #define CBUS_REG_BITS 5 | |
38 | ||
39 | struct cbus_host { | |
40 | spinlock_t lock; /* host lock */ | |
41 | struct device *dev; | |
42 | int clk_gpio; | |
43 | int dat_gpio; | |
44 | int sel_gpio; | |
45 | }; | |
46 | ||
47 | /** | |
48 | * cbus_send_bit - sends one bit over the bus | |
49 | * @host: the host we're using | |
50 | * @bit: one bit of information to send | |
51 | */ | |
52 | static void cbus_send_bit(struct cbus_host *host, unsigned bit) | |
53 | { | |
54 | gpio_set_value(host->dat_gpio, bit ? 1 : 0); | |
55 | gpio_set_value(host->clk_gpio, 1); | |
56 | gpio_set_value(host->clk_gpio, 0); | |
57 | } | |
58 | ||
59 | /** | |
60 | * cbus_send_data - sends @len amount of data over the bus | |
61 | * @host: the host we're using | |
62 | * @data: the data to send | |
63 | * @len: size of the transfer | |
64 | */ | |
65 | static void cbus_send_data(struct cbus_host *host, unsigned data, unsigned len) | |
66 | { | |
67 | int i; | |
68 | ||
69 | for (i = len; i > 0; i--) | |
70 | cbus_send_bit(host, data & (1 << (i - 1))); | |
71 | } | |
72 | ||
73 | /** | |
74 | * cbus_receive_bit - receives one bit from the bus | |
75 | * @host: the host we're using | |
76 | */ | |
77 | static int cbus_receive_bit(struct cbus_host *host) | |
78 | { | |
79 | int ret; | |
80 | ||
81 | gpio_set_value(host->clk_gpio, 1); | |
82 | ret = gpio_get_value(host->dat_gpio); | |
83 | gpio_set_value(host->clk_gpio, 0); | |
84 | return ret; | |
85 | } | |
86 | ||
87 | /** | |
88 | * cbus_receive_word - receives 16-bit word from the bus | |
89 | * @host: the host we're using | |
90 | */ | |
91 | static int cbus_receive_word(struct cbus_host *host) | |
92 | { | |
93 | int ret = 0; | |
94 | int i; | |
95 | ||
96 | for (i = 16; i > 0; i--) { | |
97 | int bit = cbus_receive_bit(host); | |
98 | ||
99 | if (bit < 0) | |
100 | return bit; | |
101 | ||
102 | if (bit) | |
103 | ret |= 1 << (i - 1); | |
104 | } | |
105 | return ret; | |
106 | } | |
107 | ||
108 | /** | |
109 | * cbus_transfer - transfers data over the bus | |
110 | * @host: the host we're using | |
111 | * @rw: read/write flag | |
112 | * @dev: device address | |
113 | * @reg: register address | |
114 | * @data: if @rw == I2C_SBUS_WRITE data to send otherwise 0 | |
115 | */ | |
116 | static int cbus_transfer(struct cbus_host *host, char rw, unsigned dev, | |
117 | unsigned reg, unsigned data) | |
118 | { | |
119 | unsigned long flags; | |
120 | int ret; | |
121 | ||
122 | /* We don't want interrupts disturbing our transfer */ | |
123 | spin_lock_irqsave(&host->lock, flags); | |
124 | ||
125 | /* Reset state and start of transfer, SEL stays down during transfer */ | |
126 | gpio_set_value(host->sel_gpio, 0); | |
127 | ||
128 | /* Set the DAT pin to output */ | |
129 | gpio_direction_output(host->dat_gpio, 1); | |
130 | ||
131 | /* Send the device address */ | |
132 | cbus_send_data(host, dev, CBUS_ADDR_BITS); | |
133 | ||
134 | /* Send the rw flag */ | |
135 | cbus_send_bit(host, rw == I2C_SMBUS_READ); | |
136 | ||
137 | /* Send the register address */ | |
138 | cbus_send_data(host, reg, CBUS_REG_BITS); | |
139 | ||
140 | if (rw == I2C_SMBUS_WRITE) { | |
141 | cbus_send_data(host, data, 16); | |
142 | ret = 0; | |
143 | } else { | |
144 | ret = gpio_direction_input(host->dat_gpio); | |
145 | if (ret) { | |
146 | dev_dbg(host->dev, "failed setting direction\n"); | |
147 | goto out; | |
148 | } | |
149 | gpio_set_value(host->clk_gpio, 1); | |
150 | ||
151 | ret = cbus_receive_word(host); | |
152 | if (ret < 0) { | |
153 | dev_dbg(host->dev, "failed receiving data\n"); | |
154 | goto out; | |
155 | } | |
156 | } | |
157 | ||
158 | /* Indicate end of transfer, SEL goes up until next transfer */ | |
159 | gpio_set_value(host->sel_gpio, 1); | |
160 | gpio_set_value(host->clk_gpio, 1); | |
161 | gpio_set_value(host->clk_gpio, 0); | |
162 | ||
163 | out: | |
164 | spin_unlock_irqrestore(&host->lock, flags); | |
165 | ||
166 | return ret; | |
167 | } | |
168 | ||
169 | static int cbus_i2c_smbus_xfer(struct i2c_adapter *adapter, | |
170 | u16 addr, | |
171 | unsigned short flags, | |
172 | char read_write, | |
173 | u8 command, | |
174 | int size, | |
175 | union i2c_smbus_data *data) | |
176 | { | |
177 | struct cbus_host *chost = i2c_get_adapdata(adapter); | |
178 | int ret; | |
179 | ||
180 | if (size != I2C_SMBUS_WORD_DATA) | |
181 | return -EINVAL; | |
182 | ||
183 | ret = cbus_transfer(chost, read_write == I2C_SMBUS_READ, addr, | |
184 | command, data->word); | |
185 | if (ret < 0) | |
186 | return ret; | |
187 | ||
188 | if (read_write == I2C_SMBUS_READ) | |
189 | data->word = ret; | |
190 | ||
191 | return 0; | |
192 | } | |
193 | ||
194 | static u32 cbus_i2c_func(struct i2c_adapter *adapter) | |
195 | { | |
196 | return I2C_FUNC_SMBUS_READ_WORD_DATA | I2C_FUNC_SMBUS_WRITE_WORD_DATA; | |
197 | } | |
198 | ||
199 | static const struct i2c_algorithm cbus_i2c_algo = { | |
200 | .smbus_xfer = cbus_i2c_smbus_xfer, | |
201 | .functionality = cbus_i2c_func, | |
202 | }; | |
203 | ||
204 | static int cbus_i2c_remove(struct platform_device *pdev) | |
205 | { | |
206 | struct i2c_adapter *adapter = platform_get_drvdata(pdev); | |
207 | ||
bf51a8c5 LPC |
208 | i2c_del_adapter(adapter); |
209 | ||
210 | return 0; | |
0857ba3c AK |
211 | } |
212 | ||
213 | static int cbus_i2c_probe(struct platform_device *pdev) | |
214 | { | |
215 | struct i2c_adapter *adapter; | |
216 | struct cbus_host *chost; | |
217 | int ret; | |
218 | ||
219 | adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter), | |
220 | GFP_KERNEL); | |
221 | if (!adapter) | |
222 | return -ENOMEM; | |
223 | ||
224 | chost = devm_kzalloc(&pdev->dev, sizeof(*chost), GFP_KERNEL); | |
225 | if (!chost) | |
226 | return -ENOMEM; | |
227 | ||
228 | if (pdev->dev.of_node) { | |
229 | struct device_node *dnode = pdev->dev.of_node; | |
230 | if (of_gpio_count(dnode) != 3) | |
231 | return -ENODEV; | |
232 | chost->clk_gpio = of_get_gpio(dnode, 0); | |
233 | chost->dat_gpio = of_get_gpio(dnode, 1); | |
234 | chost->sel_gpio = of_get_gpio(dnode, 2); | |
6d4028c6 JH |
235 | } else if (dev_get_platdata(&pdev->dev)) { |
236 | struct i2c_cbus_platform_data *pdata = | |
237 | dev_get_platdata(&pdev->dev); | |
0857ba3c AK |
238 | chost->clk_gpio = pdata->clk_gpio; |
239 | chost->dat_gpio = pdata->dat_gpio; | |
240 | chost->sel_gpio = pdata->sel_gpio; | |
241 | } else { | |
242 | return -ENODEV; | |
243 | } | |
244 | ||
245 | adapter->owner = THIS_MODULE; | |
246 | adapter->class = I2C_CLASS_HWMON; | |
247 | adapter->dev.parent = &pdev->dev; | |
de546c8a | 248 | adapter->dev.of_node = pdev->dev.of_node; |
0857ba3c AK |
249 | adapter->nr = pdev->id; |
250 | adapter->timeout = HZ; | |
251 | adapter->algo = &cbus_i2c_algo; | |
252 | strlcpy(adapter->name, "CBUS I2C adapter", sizeof(adapter->name)); | |
253 | ||
254 | spin_lock_init(&chost->lock); | |
255 | chost->dev = &pdev->dev; | |
256 | ||
257 | ret = devm_gpio_request_one(&pdev->dev, chost->clk_gpio, | |
258 | GPIOF_OUT_INIT_LOW, "CBUS clk"); | |
259 | if (ret) | |
260 | return ret; | |
261 | ||
262 | ret = devm_gpio_request_one(&pdev->dev, chost->dat_gpio, GPIOF_IN, | |
263 | "CBUS data"); | |
264 | if (ret) | |
265 | return ret; | |
266 | ||
267 | ret = devm_gpio_request_one(&pdev->dev, chost->sel_gpio, | |
268 | GPIOF_OUT_INIT_HIGH, "CBUS sel"); | |
269 | if (ret) | |
270 | return ret; | |
271 | ||
272 | i2c_set_adapdata(adapter, chost); | |
273 | platform_set_drvdata(pdev, adapter); | |
274 | ||
275 | return i2c_add_numbered_adapter(adapter); | |
276 | } | |
277 | ||
278 | #if defined(CONFIG_OF) | |
279 | static const struct of_device_id i2c_cbus_dt_ids[] = { | |
280 | { .compatible = "i2c-cbus-gpio", }, | |
281 | { } | |
282 | }; | |
283 | MODULE_DEVICE_TABLE(of, i2c_cbus_dt_ids); | |
284 | #endif | |
285 | ||
286 | static struct platform_driver cbus_i2c_driver = { | |
287 | .probe = cbus_i2c_probe, | |
288 | .remove = cbus_i2c_remove, | |
289 | .driver = { | |
0857ba3c | 290 | .name = "i2c-cbus-gpio", |
de546c8a | 291 | .of_match_table = of_match_ptr(i2c_cbus_dt_ids), |
0857ba3c AK |
292 | }, |
293 | }; | |
294 | module_platform_driver(cbus_i2c_driver); | |
295 | ||
296 | MODULE_ALIAS("platform:i2c-cbus-gpio"); | |
297 | MODULE_DESCRIPTION("CBUS I2C driver"); | |
298 | MODULE_AUTHOR("Juha Yrjölä"); | |
299 | MODULE_AUTHOR("David Weinehall"); | |
300 | MODULE_AUTHOR("Mikko Ylinen"); | |
301 | MODULE_AUTHOR("Felipe Balbi"); | |
302 | MODULE_AUTHOR("Aaro Koskinen <aaro.koskinen@iki.fi>"); | |
303 | MODULE_LICENSE("GPL"); |