1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * I2C bus driver for Kontron COM modules
4 *
5 * Copyright (c) 2010-2013 Kontron Europe GmbH
6 * Author: Michael Brunner <michael.brunner@kontron.com>
7 *
8 * The driver is based on the i2c-ocores driver by Peter Korsgaard.
9 */
10
11 #include <linux/module.h>
12 #include <linux/platform_device.h>
13 #include <linux/i2c.h>
14 #include <linux/delay.h>
15 #include <linux/mfd/kempld.h>
16
17 #define KEMPLD_I2C_PRELOW 0x0b
18 #define KEMPLD_I2C_PREHIGH 0x0c
19 #define KEMPLD_I2C_DATA 0x0e
20
21 #define KEMPLD_I2C_CTRL 0x0d
22 #define I2C_CTRL_IEN 0x40
23 #define I2C_CTRL_EN 0x80
24
25 #define KEMPLD_I2C_STAT 0x0f
26 #define I2C_STAT_IF 0x01
27 #define I2C_STAT_TIP 0x02
28 #define I2C_STAT_ARBLOST 0x20
29 #define I2C_STAT_BUSY 0x40
30 #define I2C_STAT_NACK 0x80
31
32 #define KEMPLD_I2C_CMD 0x0f
33 #define I2C_CMD_START 0x91
34 #define I2C_CMD_STOP 0x41
35 #define I2C_CMD_READ 0x21
36 #define I2C_CMD_WRITE 0x11
37 #define I2C_CMD_READ_ACK 0x21
38 #define I2C_CMD_READ_NACK 0x29
39 #define I2C_CMD_IACK 0x01
40
41 #define KEMPLD_I2C_FREQ_MAX 2700 /* 2.7 mHz */
42 #define KEMPLD_I2C_FREQ_STD 100 /* 100 kHz */
43
44 enum {
45 STATE_DONE = 0,
46 STATE_INIT,
47 STATE_ADDR,
48 STATE_ADDR10,
49 STATE_START,
50 STATE_WRITE,
51 STATE_READ,
52 STATE_ERROR,
53 };
54
55 struct kempld_i2c_data {
56 struct device *dev;
57 struct kempld_device_data *pld;
58 struct i2c_adapter adap;
59 struct i2c_msg *msg;
60 int pos;
61 int nmsgs;
62 int state;
63 bool was_active;
64 };
65
66 static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;
67 module_param(bus_frequency, uint, 0);
68 MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="
69 __MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");
70
71 static int i2c_bus = -1;
72 module_param(i2c_bus, int, 0);
73 MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");
74
75 static bool i2c_gpio_mux;
76 module_param(i2c_gpio_mux, bool, 0);
77 MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");
78
79 /*
80 * kempld_get_mutex must be called prior to calling this function.
81 */
kempld_i2c_process(struct kempld_i2c_data * i2c)82 static int kempld_i2c_process(struct kempld_i2c_data *i2c)
83 {
84 struct kempld_device_data *pld = i2c->pld;
85 u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
86 struct i2c_msg *msg = i2c->msg;
87 u8 addr;
88
89 /* Ready? */
90 if (stat & I2C_STAT_TIP)
91 return -EBUSY;
92
93 if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {
94 /* Stop has been sent */
95 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
96 if (i2c->state == STATE_ERROR)
97 return -EIO;
98 return 0;
99 }
100
101 /* Error? */
102 if (stat & I2C_STAT_ARBLOST) {
103 i2c->state = STATE_ERROR;
104 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
105 return -EAGAIN;
106 }
107
108 if (i2c->state == STATE_INIT) {
109 if (stat & I2C_STAT_BUSY)
110 return -EBUSY;
111
112 i2c->state = STATE_ADDR;
113 }
114
115 if (i2c->state == STATE_ADDR) {
116 /* 10 bit address? */
117 if (i2c->msg->flags & I2C_M_TEN) {
118 addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);
119 /* Set read bit if necessary */
120 addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;
121 i2c->state = STATE_ADDR10;
122 } else {
123 addr = i2c_8bit_addr_from_msg(i2c->msg);
124 i2c->state = STATE_START;
125 }
126
127 kempld_write8(pld, KEMPLD_I2C_DATA, addr);
128 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);
129
130 return 0;
131 }
132
133 /* Second part of 10 bit addressing */
134 if (i2c->state == STATE_ADDR10) {
135 kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);
136 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
137
138 i2c->state = STATE_START;
139 return 0;
140 }
141
142 if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {
143 i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;
144
145 if (stat & I2C_STAT_NACK) {
146 i2c->state = STATE_ERROR;
147 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
148 return -ENXIO;
149 }
150 } else {
151 msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);
152 }
153
154 if (i2c->pos >= msg->len) {
155 i2c->nmsgs--;
156 i2c->msg++;
157 i2c->pos = 0;
158 msg = i2c->msg;
159
160 if (i2c->nmsgs) {
161 if (!(msg->flags & I2C_M_NOSTART)) {
162 i2c->state = STATE_ADDR;
163 return 0;
164 } else {
165 i2c->state = (msg->flags & I2C_M_RD)
166 ? STATE_READ : STATE_WRITE;
167 }
168 } else {
169 i2c->state = STATE_DONE;
170 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
171 return 0;
172 }
173 }
174
175 if (i2c->state == STATE_READ) {
176 kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?
177 I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);
178 } else {
179 kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);
180 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);
181 }
182
183 return 0;
184 }
185
kempld_i2c_xfer(struct i2c_adapter * adap,struct i2c_msg * msgs,int num)186 static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
187 int num)
188 {
189 struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);
190 struct kempld_device_data *pld = i2c->pld;
191 unsigned long timeout = jiffies + HZ;
192 int ret;
193
194 i2c->msg = msgs;
195 i2c->pos = 0;
196 i2c->nmsgs = num;
197 i2c->state = STATE_INIT;
198
199 /* Handle the transfer */
200 while (time_before(jiffies, timeout)) {
201 kempld_get_mutex(pld);
202 ret = kempld_i2c_process(i2c);
203 kempld_release_mutex(pld);
204
205 if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
206 return (i2c->state == STATE_DONE) ? num : ret;
207
208 if (ret == 0)
209 timeout = jiffies + HZ;
210
211 usleep_range(5, 15);
212 }
213
214 i2c->state = STATE_ERROR;
215
216 return -ETIMEDOUT;
217 }
218
219 /*
220 * kempld_get_mutex must be called prior to calling this function.
221 */
kempld_i2c_device_init(struct kempld_i2c_data * i2c)222 static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)
223 {
224 struct kempld_device_data *pld = i2c->pld;
225 u16 prescale_corr;
226 long prescale;
227 u8 ctrl;
228 u8 stat;
229 u8 cfg;
230
231 /* Make sure the device is disabled */
232 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
233 ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);
234 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
235
236 if (bus_frequency > KEMPLD_I2C_FREQ_MAX)
237 bus_frequency = KEMPLD_I2C_FREQ_MAX;
238
239 if (pld->info.spec_major == 1)
240 prescale = pld->pld_clock / (bus_frequency * 5) - 1000;
241 else
242 prescale = pld->pld_clock / (bus_frequency * 4) - 3000;
243
244 if (prescale < 0)
245 prescale = 0;
246
247 /* Round to the best matching value */
248 prescale_corr = prescale / 1000;
249 if (prescale % 1000 >= 500)
250 prescale_corr++;
251
252 kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);
253 kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);
254
255 /* Activate I2C bus output on GPIO pins */
256 cfg = kempld_read8(pld, KEMPLD_CFG);
257 if (i2c_gpio_mux)
258 cfg |= KEMPLD_CFG_GPIO_I2C_MUX;
259 else
260 cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;
261 kempld_write8(pld, KEMPLD_CFG, cfg);
262
263 /* Enable the device */
264 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);
265 ctrl |= I2C_CTRL_EN;
266 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
267
268 stat = kempld_read8(pld, KEMPLD_I2C_STAT);
269 if (stat & I2C_STAT_BUSY)
270 kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);
271 }
272
kempld_i2c_func(struct i2c_adapter * adap)273 static u32 kempld_i2c_func(struct i2c_adapter *adap)
274 {
275 return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;
276 }
277
278 static const struct i2c_algorithm kempld_i2c_algorithm = {
279 .master_xfer = kempld_i2c_xfer,
280 .functionality = kempld_i2c_func,
281 };
282
283 static const struct i2c_adapter kempld_i2c_adapter = {
284 .owner = THIS_MODULE,
285 .name = "i2c-kempld",
286 .class = I2C_CLASS_HWMON | I2C_CLASS_SPD,
287 .algo = &kempld_i2c_algorithm,
288 };
289
kempld_i2c_probe(struct platform_device * pdev)290 static int kempld_i2c_probe(struct platform_device *pdev)
291 {
292 struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);
293 struct kempld_i2c_data *i2c;
294 int ret;
295 u8 ctrl;
296
297 i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
298 if (!i2c)
299 return -ENOMEM;
300
301 i2c->pld = pld;
302 i2c->dev = &pdev->dev;
303 i2c->adap = kempld_i2c_adapter;
304 i2c->adap.dev.parent = i2c->dev;
305 i2c_set_adapdata(&i2c->adap, i2c);
306 platform_set_drvdata(pdev, i2c);
307
308 kempld_get_mutex(pld);
309 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
310
311 if (ctrl & I2C_CTRL_EN)
312 i2c->was_active = true;
313
314 kempld_i2c_device_init(i2c);
315 kempld_release_mutex(pld);
316
317 /* Add I2C adapter to I2C tree */
318 if (i2c_bus >= -1)
319 i2c->adap.nr = i2c_bus;
320 ret = i2c_add_numbered_adapter(&i2c->adap);
321 if (ret)
322 return ret;
323
324 dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",
325 bus_frequency);
326
327 return 0;
328 }
329
kempld_i2c_remove(struct platform_device * pdev)330 static int kempld_i2c_remove(struct platform_device *pdev)
331 {
332 struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
333 struct kempld_device_data *pld = i2c->pld;
334 u8 ctrl;
335
336 kempld_get_mutex(pld);
337 /*
338 * Disable I2C logic if it was not activated before the
339 * driver loaded
340 */
341 if (!i2c->was_active) {
342 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
343 ctrl &= ~I2C_CTRL_EN;
344 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
345 }
346 kempld_release_mutex(pld);
347
348 i2c_del_adapter(&i2c->adap);
349
350 return 0;
351 }
352
353 #ifdef CONFIG_PM
kempld_i2c_suspend(struct platform_device * pdev,pm_message_t state)354 static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)
355 {
356 struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
357 struct kempld_device_data *pld = i2c->pld;
358 u8 ctrl;
359
360 kempld_get_mutex(pld);
361 ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);
362 ctrl &= ~I2C_CTRL_EN;
363 kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);
364 kempld_release_mutex(pld);
365
366 return 0;
367 }
368
kempld_i2c_resume(struct platform_device * pdev)369 static int kempld_i2c_resume(struct platform_device *pdev)
370 {
371 struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);
372 struct kempld_device_data *pld = i2c->pld;
373
374 kempld_get_mutex(pld);
375 kempld_i2c_device_init(i2c);
376 kempld_release_mutex(pld);
377
378 return 0;
379 }
380 #else
381 #define kempld_i2c_suspend NULL
382 #define kempld_i2c_resume NULL
383 #endif
384
385 static struct platform_driver kempld_i2c_driver = {
386 .driver = {
387 .name = "kempld-i2c",
388 },
389 .probe = kempld_i2c_probe,
390 .remove = kempld_i2c_remove,
391 .suspend = kempld_i2c_suspend,
392 .resume = kempld_i2c_resume,
393 };
394
395 module_platform_driver(kempld_i2c_driver);
396
397 MODULE_DESCRIPTION("KEM PLD I2C Driver");
398 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
399 MODULE_LICENSE("GPL");
400 MODULE_ALIAS("platform:kempld_i2c");
401