i2c: add support for the Digicolor I2C controller
[deliverable/linux.git] / drivers / i2c / busses / i2c-digicolor.c
CommitLineData
4a7a0822
BS
1/*
2 * I2C bus driver for Conexant Digicolor SoCs
3 *
4 * Author: Baruch Siach <baruch@tkos.co.il>
5 *
6 * Copyright (C) 2015 Paradox Innovation Ltd.
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/clk.h>
14#include <linux/completion.h>
15#include <linux/i2c.h>
16#include <linux/interrupt.h>
17#include <linux/io.h>
18#include <linux/clk.h>
19#include <linux/delay.h>
20#include <linux/kernel.h>
21#include <linux/module.h>
22#include <linux/of.h>
23#include <linux/platform_device.h>
24
25#define DEFAULT_FREQ 100000
26#define TIMEOUT_MS 100
27
28#define II_CONTROL 0x0
29#define II_CONTROL_LOCAL_RESET BIT(0)
30
31#define II_CLOCKTIME 0x1
32
33#define II_COMMAND 0x2
34#define II_CMD_START 1
35#define II_CMD_RESTART 2
36#define II_CMD_SEND_ACK 3
37#define II_CMD_GET_ACK 6
38#define II_CMD_GET_NOACK 7
39#define II_CMD_STOP 10
40#define II_COMMAND_GO BIT(7)
41#define II_COMMAND_COMPLETION_STATUS(r) (((r) >> 5) & 3)
42#define II_CMD_STATUS_NORMAL 0
43#define II_CMD_STATUS_ACK_GOOD 1
44#define II_CMD_STATUS_ACK_BAD 2
45#define II_CMD_STATUS_ABORT 3
46
47#define II_DATA 0x3
48#define II_INTFLAG_CLEAR 0x8
49#define II_INTENABLE 0xa
50
51struct dc_i2c {
52 struct i2c_adapter adap;
53 struct device *dev;
54 void __iomem *regs;
55 struct clk *clk;
56 unsigned int frequency;
57
58 struct i2c_msg *msg;
59 unsigned int msgbuf_ptr;
60 int last;
61 spinlock_t lock;
62 struct completion done;
63 int state;
64 int error;
65};
66
67enum {
68 STATE_IDLE,
69 STATE_START,
70 STATE_ADDR,
71 STATE_WRITE,
72 STATE_READ,
73 STATE_STOP,
74};
75
76static void dc_i2c_cmd(struct dc_i2c *i2c, u8 cmd)
77{
78 writeb_relaxed(cmd | II_COMMAND_GO, i2c->regs + II_COMMAND);
79}
80
81static u8 dc_i2c_addr_cmd(struct i2c_msg *msg)
82{
83 u8 addr = (msg->addr & 0x7f) << 1;
84
85 if (msg->flags & I2C_M_RD)
86 addr |= 1;
87
88 return addr;
89}
90
91static void dc_i2c_data(struct dc_i2c *i2c, u8 data)
92{
93 writeb_relaxed(data, i2c->regs + II_DATA);
94}
95
96static void dc_i2c_write_byte(struct dc_i2c *i2c, u8 byte)
97{
98 dc_i2c_data(i2c, byte);
99 dc_i2c_cmd(i2c, II_CMD_SEND_ACK);
100}
101
102static void dc_i2c_write_buf(struct dc_i2c *i2c)
103{
104 dc_i2c_write_byte(i2c, i2c->msg->buf[i2c->msgbuf_ptr++]);
105}
106
107static void dc_i2c_next_read(struct dc_i2c *i2c)
108{
109 bool last = (i2c->msgbuf_ptr + 1 == i2c->msg->len);
110
111 dc_i2c_cmd(i2c, last ? II_CMD_GET_NOACK : II_CMD_GET_ACK);
112}
113
114static void dc_i2c_stop(struct dc_i2c *i2c)
115{
116 i2c->state = STATE_STOP;
117 if (i2c->last)
118 dc_i2c_cmd(i2c, II_CMD_STOP);
119 else
120 complete(&i2c->done);
121}
122
123static u8 dc_i2c_read_byte(struct dc_i2c *i2c)
124{
125 return readb_relaxed(i2c->regs + II_DATA);
126}
127
128static void dc_i2c_read_buf(struct dc_i2c *i2c)
129{
130 i2c->msg->buf[i2c->msgbuf_ptr++] = dc_i2c_read_byte(i2c);
131 dc_i2c_next_read(i2c);
132}
133
134static void dc_i2c_set_irq(struct dc_i2c *i2c, int enable)
135{
136 if (enable)
137 writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
138 writeb_relaxed(!!enable, i2c->regs + II_INTENABLE);
139}
140
141static int dc_i2c_cmd_status(struct dc_i2c *i2c)
142{
143 u8 cmd = readb_relaxed(i2c->regs + II_COMMAND);
144
145 return II_COMMAND_COMPLETION_STATUS(cmd);
146}
147
148static void dc_i2c_start_msg(struct dc_i2c *i2c, int first)
149{
150 struct i2c_msg *msg = i2c->msg;
151
152 if (!(msg->flags & I2C_M_NOSTART)) {
153 i2c->state = STATE_START;
154 dc_i2c_cmd(i2c, first ? II_CMD_START : II_CMD_RESTART);
155 } else if (msg->flags & I2C_M_RD) {
156 i2c->state = STATE_READ;
157 dc_i2c_next_read(i2c);
158 } else {
159 i2c->state = STATE_WRITE;
160 dc_i2c_write_buf(i2c);
161 }
162}
163
164static irqreturn_t dc_i2c_irq(int irq, void *dev_id)
165{
166 struct dc_i2c *i2c = dev_id;
167 int cmd_status = dc_i2c_cmd_status(i2c);
168 unsigned long flags;
169 u8 addr_cmd;
170
171 writeb_relaxed(1, i2c->regs + II_INTFLAG_CLEAR);
172
173 spin_lock_irqsave(&i2c->lock, flags);
174
175 if (cmd_status == II_CMD_STATUS_ACK_BAD
176 || cmd_status == II_CMD_STATUS_ABORT) {
177 i2c->error = -EIO;
178 complete(&i2c->done);
179 goto out;
180 }
181
182 switch (i2c->state) {
183 case STATE_START:
184 addr_cmd = dc_i2c_addr_cmd(i2c->msg);
185 dc_i2c_write_byte(i2c, addr_cmd);
186 i2c->state = STATE_ADDR;
187 break;
188 case STATE_ADDR:
189 if (i2c->msg->flags & I2C_M_RD) {
190 dc_i2c_next_read(i2c);
191 i2c->state = STATE_READ;
192 break;
193 }
194 i2c->state = STATE_WRITE;
195 /* fall through */
196 case STATE_WRITE:
197 if (i2c->msgbuf_ptr < i2c->msg->len)
198 dc_i2c_write_buf(i2c);
199 else
200 dc_i2c_stop(i2c);
201 break;
202 case STATE_READ:
203 if (i2c->msgbuf_ptr < i2c->msg->len)
204 dc_i2c_read_buf(i2c);
205 else
206 dc_i2c_stop(i2c);
207 break;
208 case STATE_STOP:
209 i2c->state = STATE_IDLE;
210 complete(&i2c->done);
211 break;
212 }
213
214out:
215 spin_unlock_irqrestore(&i2c->lock, flags);
216 return IRQ_HANDLED;
217}
218
219static int dc_i2c_xfer_msg(struct dc_i2c *i2c, struct i2c_msg *msg, int first,
220 int last)
221{
222 unsigned long timeout = msecs_to_jiffies(TIMEOUT_MS);
223 unsigned long flags;
224
225 spin_lock_irqsave(&i2c->lock, flags);
226 i2c->msg = msg;
227 i2c->msgbuf_ptr = 0;
228 i2c->last = last;
229 i2c->error = 0;
230
231 reinit_completion(&i2c->done);
232 dc_i2c_set_irq(i2c, 1);
233 dc_i2c_start_msg(i2c, first);
234 spin_unlock_irqrestore(&i2c->lock, flags);
235
236 timeout = wait_for_completion_timeout(&i2c->done, timeout);
237 dc_i2c_set_irq(i2c, 0);
238 if (timeout == 0) {
239 i2c->state = STATE_IDLE;
240 return -ETIMEDOUT;
241 }
242
243 if (i2c->error)
244 return i2c->error;
245
246 return 0;
247}
248
249static int dc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
250{
251 struct dc_i2c *i2c = adap->algo_data;
252 int i, ret;
253
254 for (i = 0; i < num; i++) {
255 ret = dc_i2c_xfer_msg(i2c, &msgs[i], i == 0, i == num - 1);
256 if (ret)
257 return ret;
258 }
259
260 return num;
261}
262
263static int dc_i2c_init_hw(struct dc_i2c *i2c)
264{
265 unsigned long clk_rate = clk_get_rate(i2c->clk);
266 unsigned int clocktime;
267
268 writeb_relaxed(II_CONTROL_LOCAL_RESET, i2c->regs + II_CONTROL);
269 udelay(100);
270 writeb_relaxed(0, i2c->regs + II_CONTROL);
271 udelay(100);
272
273 clocktime = DIV_ROUND_UP(clk_rate, 64 * i2c->frequency);
274 if (clocktime < 1 || clocktime > 0xff) {
275 dev_err(i2c->dev, "can't set bus speed of %u Hz\n",
276 i2c->frequency);
277 return -EINVAL;
278 }
279 writeb_relaxed(clocktime - 1, i2c->regs + II_CLOCKTIME);
280
281 return 0;
282}
283
284static u32 dc_i2c_func(struct i2c_adapter *adap)
285{
286 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART;
287}
288
289static const struct i2c_algorithm dc_i2c_algorithm = {
290 .master_xfer = dc_i2c_xfer,
291 .functionality = dc_i2c_func,
292};
293
294static int dc_i2c_probe(struct platform_device *pdev)
295{
296 struct device_node *np = pdev->dev.of_node;
297 struct dc_i2c *i2c;
298 struct resource *r;
299 int ret = 0, irq;
300
301 i2c = devm_kzalloc(&pdev->dev, sizeof(struct dc_i2c), GFP_KERNEL);
302 if (!i2c)
303 return -ENOMEM;
304
305 if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
306 &i2c->frequency))
307 i2c->frequency = DEFAULT_FREQ;
308
309 i2c->dev = &pdev->dev;
310 platform_set_drvdata(pdev, i2c);
311
312 spin_lock_init(&i2c->lock);
313 init_completion(&i2c->done);
314
315 i2c->clk = devm_clk_get(&pdev->dev, NULL);
316 if (IS_ERR(i2c->clk))
317 return PTR_ERR(i2c->clk);
318
319 r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
320 i2c->regs = devm_ioremap_resource(&pdev->dev, r);
321 if (IS_ERR(i2c->regs))
322 return PTR_ERR(i2c->regs);
323
324 irq = platform_get_irq(pdev, 0);
325 if (irq < 0)
326 return irq;
327
328 ret = devm_request_irq(&pdev->dev, irq, dc_i2c_irq, 0,
329 dev_name(&pdev->dev), i2c);
330 if (ret < 0)
331 return ret;
332
333 strlcpy(i2c->adap.name, "Conexant Digicolor I2C adapter",
334 sizeof(i2c->adap.name));
335 i2c->adap.owner = THIS_MODULE;
336 i2c->adap.algo = &dc_i2c_algorithm;
337 i2c->adap.dev.parent = &pdev->dev;
338 i2c->adap.dev.of_node = np;
339 i2c->adap.algo_data = i2c;
340
341 ret = dc_i2c_init_hw(i2c);
342 if (ret)
343 return ret;
344
345 ret = clk_prepare_enable(i2c->clk);
346 if (ret < 0)
347 return ret;
348
349 ret = i2c_add_adapter(&i2c->adap);
350 if (ret < 0) {
351 clk_unprepare(i2c->clk);
352 return ret;
353 }
354
355 return 0;
356}
357
358static int dc_i2c_remove(struct platform_device *pdev)
359{
360 struct dc_i2c *i2c = platform_get_drvdata(pdev);
361
362 i2c_del_adapter(&i2c->adap);
363 clk_disable_unprepare(i2c->clk);
364
365 return 0;
366}
367
368static const struct of_device_id dc_i2c_match[] = {
369 { .compatible = "cnxt,cx92755-i2c" },
370 { },
371};
372
373static struct platform_driver dc_i2c_driver = {
374 .probe = dc_i2c_probe,
375 .remove = dc_i2c_remove,
376 .driver = {
377 .name = "digicolor-i2c",
378 .of_match_table = dc_i2c_match,
379 },
380};
381module_platform_driver(dc_i2c_driver);
382
383MODULE_AUTHOR("Baruch Siach <baruch@tkos.co.il>");
384MODULE_DESCRIPTION("Conexant Digicolor I2C master driver");
385MODULE_LICENSE("GPL v2");
This page took 0.037786 seconds and 5 git commands to generate.