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 | */ |
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(msg: i2c->msg); |
124 | i2c->state = STATE_START; |
125 | } |
126 | |
127 | kempld_write8(pld, KEMPLD_I2C_DATA, 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, 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, data: i2c->pos == (msg->len - 1) ? |
177 | I2C_CMD_READ_NACK : I2C_CMD_READ_ACK); |
178 | } else { |
179 | kempld_write8(pld, KEMPLD_I2C_DATA, data: msg->buf[i2c->pos++]); |
180 | kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE); |
181 | } |
182 | |
183 | return 0; |
184 | } |
185 | |
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(min: 5, max: 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 | */ |
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, data: 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, data: prescale_corr & 0xff); |
253 | kempld_write8(pld, KEMPLD_I2C_PREHIGH, data: 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, data: 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, data: 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 | |
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_DEPRECATED, |
287 | .algo = &kempld_i2c_algorithm, |
288 | }; |
289 | |
290 | static int kempld_i2c_probe(struct platform_device *pdev) |
291 | { |
292 | struct kempld_device_data *pld = dev_get_drvdata(dev: pdev->dev.parent); |
293 | struct kempld_i2c_data *i2c; |
294 | int ret; |
295 | u8 ctrl; |
296 | |
297 | i2c = devm_kzalloc(dev: &pdev->dev, size: 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 | ACPI_COMPANION_SET(&i2c->adap.dev, ACPI_COMPANION(&pdev->dev)); |
306 | i2c_set_adapdata(adap: &i2c->adap, data: i2c); |
307 | platform_set_drvdata(pdev, data: i2c); |
308 | |
309 | kempld_get_mutex(pld); |
310 | ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL); |
311 | |
312 | if (ctrl & I2C_CTRL_EN) |
313 | i2c->was_active = true; |
314 | |
315 | kempld_i2c_device_init(i2c); |
316 | kempld_release_mutex(pld); |
317 | |
318 | /* Add I2C adapter to I2C tree */ |
319 | if (i2c_bus >= -1) |
320 | i2c->adap.nr = i2c_bus; |
321 | ret = i2c_add_numbered_adapter(adap: &i2c->adap); |
322 | if (ret) |
323 | return ret; |
324 | |
325 | dev_info(i2c->dev, "I2C bus initialized at %dkHz\n" , |
326 | bus_frequency); |
327 | |
328 | return 0; |
329 | } |
330 | |
331 | static void kempld_i2c_remove(struct platform_device *pdev) |
332 | { |
333 | struct kempld_i2c_data *i2c = platform_get_drvdata(pdev); |
334 | struct kempld_device_data *pld = i2c->pld; |
335 | u8 ctrl; |
336 | |
337 | kempld_get_mutex(pld); |
338 | /* |
339 | * Disable I2C logic if it was not activated before the |
340 | * driver loaded |
341 | */ |
342 | if (!i2c->was_active) { |
343 | ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL); |
344 | ctrl &= ~I2C_CTRL_EN; |
345 | kempld_write8(pld, KEMPLD_I2C_CTRL, data: ctrl); |
346 | } |
347 | kempld_release_mutex(pld); |
348 | |
349 | i2c_del_adapter(adap: &i2c->adap); |
350 | } |
351 | |
352 | static int kempld_i2c_suspend(struct device *dev) |
353 | { |
354 | struct kempld_i2c_data *i2c = dev_get_drvdata(dev); |
355 | struct kempld_device_data *pld = i2c->pld; |
356 | u8 ctrl; |
357 | |
358 | kempld_get_mutex(pld); |
359 | ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL); |
360 | ctrl &= ~I2C_CTRL_EN; |
361 | kempld_write8(pld, KEMPLD_I2C_CTRL, data: ctrl); |
362 | kempld_release_mutex(pld); |
363 | |
364 | return 0; |
365 | } |
366 | |
367 | static int kempld_i2c_resume(struct device *dev) |
368 | { |
369 | struct kempld_i2c_data *i2c = dev_get_drvdata(dev); |
370 | struct kempld_device_data *pld = i2c->pld; |
371 | |
372 | kempld_get_mutex(pld); |
373 | kempld_i2c_device_init(i2c); |
374 | kempld_release_mutex(pld); |
375 | |
376 | return 0; |
377 | } |
378 | |
379 | static DEFINE_SIMPLE_DEV_PM_OPS(kempld_i2c_pm_ops, |
380 | kempld_i2c_suspend, kempld_i2c_resume); |
381 | |
382 | static struct platform_driver kempld_i2c_driver = { |
383 | .driver = { |
384 | .name = "kempld-i2c" , |
385 | .pm = pm_sleep_ptr(&kempld_i2c_pm_ops), |
386 | }, |
387 | .probe = kempld_i2c_probe, |
388 | .remove_new = kempld_i2c_remove, |
389 | }; |
390 | |
391 | module_platform_driver(kempld_i2c_driver); |
392 | |
393 | MODULE_DESCRIPTION("KEM PLD I2C Driver" ); |
394 | MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>" ); |
395 | MODULE_LICENSE("GPL" ); |
396 | MODULE_ALIAS("platform:kempld_i2c" ); |
397 | |