1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * STM32 Low-Power Timer Encoder and Counter driver
4 *
5 * Copyright (C) STMicroelectronics 2017
6 *
7 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
8 *
9 * Inspired by 104-quad-8 and stm32-timer-trigger drivers.
10 *
11 */
12
13 #include <linux/bitfield.h>
14 #include <linux/counter.h>
15 #include <linux/mfd/stm32-lptimer.h>
16 #include <linux/mod_devicetable.h>
17 #include <linux/module.h>
18 #include <linux/pinctrl/consumer.h>
19 #include <linux/platform_device.h>
20
21 struct stm32_lptim_cnt {
22 struct counter_device counter;
23 struct device *dev;
24 struct regmap *regmap;
25 struct clk *clk;
26 u32 ceiling;
27 u32 polarity;
28 u32 quadrature_mode;
29 bool enabled;
30 };
31
stm32_lptim_is_enabled(struct stm32_lptim_cnt * priv)32 static int stm32_lptim_is_enabled(struct stm32_lptim_cnt *priv)
33 {
34 u32 val;
35 int ret;
36
37 ret = regmap_read(priv->regmap, STM32_LPTIM_CR, &val);
38 if (ret)
39 return ret;
40
41 return FIELD_GET(STM32_LPTIM_ENABLE, val);
42 }
43
stm32_lptim_set_enable_state(struct stm32_lptim_cnt * priv,int enable)44 static int stm32_lptim_set_enable_state(struct stm32_lptim_cnt *priv,
45 int enable)
46 {
47 int ret;
48 u32 val;
49
50 val = FIELD_PREP(STM32_LPTIM_ENABLE, enable);
51 ret = regmap_write(priv->regmap, STM32_LPTIM_CR, val);
52 if (ret)
53 return ret;
54
55 if (!enable) {
56 clk_disable(priv->clk);
57 priv->enabled = false;
58 return 0;
59 }
60
61 /* LP timer must be enabled before writing CMP & ARR */
62 ret = regmap_write(priv->regmap, STM32_LPTIM_ARR, priv->ceiling);
63 if (ret)
64 return ret;
65
66 ret = regmap_write(priv->regmap, STM32_LPTIM_CMP, 0);
67 if (ret)
68 return ret;
69
70 /* ensure CMP & ARR registers are properly written */
71 ret = regmap_read_poll_timeout(priv->regmap, STM32_LPTIM_ISR, val,
72 (val & STM32_LPTIM_CMPOK_ARROK) == STM32_LPTIM_CMPOK_ARROK,
73 100, 1000);
74 if (ret)
75 return ret;
76
77 ret = regmap_write(priv->regmap, STM32_LPTIM_ICR,
78 STM32_LPTIM_CMPOKCF_ARROKCF);
79 if (ret)
80 return ret;
81
82 ret = clk_enable(priv->clk);
83 if (ret) {
84 regmap_write(priv->regmap, STM32_LPTIM_CR, 0);
85 return ret;
86 }
87 priv->enabled = true;
88
89 /* Start LP timer in continuous mode */
90 return regmap_update_bits(priv->regmap, STM32_LPTIM_CR,
91 STM32_LPTIM_CNTSTRT, STM32_LPTIM_CNTSTRT);
92 }
93
stm32_lptim_setup(struct stm32_lptim_cnt * priv,int enable)94 static int stm32_lptim_setup(struct stm32_lptim_cnt *priv, int enable)
95 {
96 u32 mask = STM32_LPTIM_ENC | STM32_LPTIM_COUNTMODE |
97 STM32_LPTIM_CKPOL | STM32_LPTIM_PRESC;
98 u32 val;
99
100 /* Setup LP timer encoder/counter and polarity, without prescaler */
101 if (priv->quadrature_mode)
102 val = enable ? STM32_LPTIM_ENC : 0;
103 else
104 val = enable ? STM32_LPTIM_COUNTMODE : 0;
105 val |= FIELD_PREP(STM32_LPTIM_CKPOL, enable ? priv->polarity : 0);
106
107 return regmap_update_bits(priv->regmap, STM32_LPTIM_CFGR, mask, val);
108 }
109
110 /**
111 * enum stm32_lptim_cnt_function - enumerates LPTimer counter & encoder modes
112 * @STM32_LPTIM_COUNTER_INCREASE: up count on IN1 rising, falling or both edges
113 * @STM32_LPTIM_ENCODER_BOTH_EDGE: count on both edges (IN1 & IN2 quadrature)
114 *
115 * In non-quadrature mode, device counts up on active edge.
116 * In quadrature mode, encoder counting scenarios are as follows:
117 * +---------+----------+--------------------+--------------------+
118 * | Active | Level on | IN1 signal | IN2 signal |
119 * | edge | opposite +----------+---------+----------+---------+
120 * | | signal | Rising | Falling | Rising | Falling |
121 * +---------+----------+----------+---------+----------+---------+
122 * | Rising | High -> | Down | - | Up | - |
123 * | edge | Low -> | Up | - | Down | - |
124 * +---------+----------+----------+---------+----------+---------+
125 * | Falling | High -> | - | Up | - | Down |
126 * | edge | Low -> | - | Down | - | Up |
127 * +---------+----------+----------+---------+----------+---------+
128 * | Both | High -> | Down | Up | Up | Down |
129 * | edges | Low -> | Up | Down | Down | Up |
130 * +---------+----------+----------+---------+----------+---------+
131 */
132 enum stm32_lptim_cnt_function {
133 STM32_LPTIM_COUNTER_INCREASE,
134 STM32_LPTIM_ENCODER_BOTH_EDGE,
135 };
136
137 static enum counter_count_function stm32_lptim_cnt_functions[] = {
138 [STM32_LPTIM_COUNTER_INCREASE] = COUNTER_COUNT_FUNCTION_INCREASE,
139 [STM32_LPTIM_ENCODER_BOTH_EDGE] = COUNTER_COUNT_FUNCTION_QUADRATURE_X4,
140 };
141
142 enum stm32_lptim_synapse_action {
143 STM32_LPTIM_SYNAPSE_ACTION_RISING_EDGE,
144 STM32_LPTIM_SYNAPSE_ACTION_FALLING_EDGE,
145 STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES,
146 STM32_LPTIM_SYNAPSE_ACTION_NONE,
147 };
148
149 static enum counter_synapse_action stm32_lptim_cnt_synapse_actions[] = {
150 /* Index must match with stm32_lptim_cnt_polarity[] (priv->polarity) */
151 [STM32_LPTIM_SYNAPSE_ACTION_RISING_EDGE] = COUNTER_SYNAPSE_ACTION_RISING_EDGE,
152 [STM32_LPTIM_SYNAPSE_ACTION_FALLING_EDGE] = COUNTER_SYNAPSE_ACTION_FALLING_EDGE,
153 [STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES] = COUNTER_SYNAPSE_ACTION_BOTH_EDGES,
154 [STM32_LPTIM_SYNAPSE_ACTION_NONE] = COUNTER_SYNAPSE_ACTION_NONE,
155 };
156
stm32_lptim_cnt_read(struct counter_device * counter,struct counter_count * count,unsigned long * val)157 static int stm32_lptim_cnt_read(struct counter_device *counter,
158 struct counter_count *count, unsigned long *val)
159 {
160 struct stm32_lptim_cnt *const priv = counter->priv;
161 u32 cnt;
162 int ret;
163
164 ret = regmap_read(priv->regmap, STM32_LPTIM_CNT, &cnt);
165 if (ret)
166 return ret;
167
168 *val = cnt;
169
170 return 0;
171 }
172
stm32_lptim_cnt_function_get(struct counter_device * counter,struct counter_count * count,size_t * function)173 static int stm32_lptim_cnt_function_get(struct counter_device *counter,
174 struct counter_count *count,
175 size_t *function)
176 {
177 struct stm32_lptim_cnt *const priv = counter->priv;
178
179 if (!priv->quadrature_mode) {
180 *function = STM32_LPTIM_COUNTER_INCREASE;
181 return 0;
182 }
183
184 if (priv->polarity == STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES) {
185 *function = STM32_LPTIM_ENCODER_BOTH_EDGE;
186 return 0;
187 }
188
189 return -EINVAL;
190 }
191
stm32_lptim_cnt_function_set(struct counter_device * counter,struct counter_count * count,size_t function)192 static int stm32_lptim_cnt_function_set(struct counter_device *counter,
193 struct counter_count *count,
194 size_t function)
195 {
196 struct stm32_lptim_cnt *const priv = counter->priv;
197
198 if (stm32_lptim_is_enabled(priv))
199 return -EBUSY;
200
201 switch (function) {
202 case STM32_LPTIM_COUNTER_INCREASE:
203 priv->quadrature_mode = 0;
204 return 0;
205 case STM32_LPTIM_ENCODER_BOTH_EDGE:
206 priv->quadrature_mode = 1;
207 priv->polarity = STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES;
208 return 0;
209 }
210
211 return -EINVAL;
212 }
213
stm32_lptim_cnt_enable_read(struct counter_device * counter,struct counter_count * count,void * private,char * buf)214 static ssize_t stm32_lptim_cnt_enable_read(struct counter_device *counter,
215 struct counter_count *count,
216 void *private, char *buf)
217 {
218 struct stm32_lptim_cnt *const priv = counter->priv;
219 int ret;
220
221 ret = stm32_lptim_is_enabled(priv);
222 if (ret < 0)
223 return ret;
224
225 return scnprintf(buf, PAGE_SIZE, "%u\n", ret);
226 }
227
stm32_lptim_cnt_enable_write(struct counter_device * counter,struct counter_count * count,void * private,const char * buf,size_t len)228 static ssize_t stm32_lptim_cnt_enable_write(struct counter_device *counter,
229 struct counter_count *count,
230 void *private,
231 const char *buf, size_t len)
232 {
233 struct stm32_lptim_cnt *const priv = counter->priv;
234 bool enable;
235 int ret;
236
237 ret = kstrtobool(buf, &enable);
238 if (ret)
239 return ret;
240
241 /* Check nobody uses the timer, or already disabled/enabled */
242 ret = stm32_lptim_is_enabled(priv);
243 if ((ret < 0) || (!ret && !enable))
244 return ret;
245 if (enable && ret)
246 return -EBUSY;
247
248 ret = stm32_lptim_setup(priv, enable);
249 if (ret)
250 return ret;
251
252 ret = stm32_lptim_set_enable_state(priv, enable);
253 if (ret)
254 return ret;
255
256 return len;
257 }
258
stm32_lptim_cnt_ceiling_read(struct counter_device * counter,struct counter_count * count,void * private,char * buf)259 static ssize_t stm32_lptim_cnt_ceiling_read(struct counter_device *counter,
260 struct counter_count *count,
261 void *private, char *buf)
262 {
263 struct stm32_lptim_cnt *const priv = counter->priv;
264
265 return snprintf(buf, PAGE_SIZE, "%u\n", priv->ceiling);
266 }
267
stm32_lptim_cnt_ceiling_write(struct counter_device * counter,struct counter_count * count,void * private,const char * buf,size_t len)268 static ssize_t stm32_lptim_cnt_ceiling_write(struct counter_device *counter,
269 struct counter_count *count,
270 void *private,
271 const char *buf, size_t len)
272 {
273 struct stm32_lptim_cnt *const priv = counter->priv;
274 unsigned int ceiling;
275 int ret;
276
277 if (stm32_lptim_is_enabled(priv))
278 return -EBUSY;
279
280 ret = kstrtouint(buf, 0, &ceiling);
281 if (ret)
282 return ret;
283
284 if (ceiling > STM32_LPTIM_MAX_ARR)
285 return -EINVAL;
286
287 priv->ceiling = ceiling;
288
289 return len;
290 }
291
292 static const struct counter_count_ext stm32_lptim_cnt_ext[] = {
293 {
294 .name = "enable",
295 .read = stm32_lptim_cnt_enable_read,
296 .write = stm32_lptim_cnt_enable_write
297 },
298 {
299 .name = "ceiling",
300 .read = stm32_lptim_cnt_ceiling_read,
301 .write = stm32_lptim_cnt_ceiling_write
302 },
303 };
304
stm32_lptim_cnt_action_get(struct counter_device * counter,struct counter_count * count,struct counter_synapse * synapse,size_t * action)305 static int stm32_lptim_cnt_action_get(struct counter_device *counter,
306 struct counter_count *count,
307 struct counter_synapse *synapse,
308 size_t *action)
309 {
310 struct stm32_lptim_cnt *const priv = counter->priv;
311 size_t function;
312 int err;
313
314 err = stm32_lptim_cnt_function_get(counter, count, &function);
315 if (err)
316 return err;
317
318 switch (function) {
319 case STM32_LPTIM_COUNTER_INCREASE:
320 /* LP Timer acts as up-counter on input 1 */
321 if (synapse->signal->id == count->synapses[0].signal->id)
322 *action = priv->polarity;
323 else
324 *action = STM32_LPTIM_SYNAPSE_ACTION_NONE;
325 return 0;
326 case STM32_LPTIM_ENCODER_BOTH_EDGE:
327 *action = priv->polarity;
328 return 0;
329 }
330
331 return -EINVAL;
332 }
333
stm32_lptim_cnt_action_set(struct counter_device * counter,struct counter_count * count,struct counter_synapse * synapse,size_t action)334 static int stm32_lptim_cnt_action_set(struct counter_device *counter,
335 struct counter_count *count,
336 struct counter_synapse *synapse,
337 size_t action)
338 {
339 struct stm32_lptim_cnt *const priv = counter->priv;
340 size_t function;
341 int err;
342
343 if (stm32_lptim_is_enabled(priv))
344 return -EBUSY;
345
346 err = stm32_lptim_cnt_function_get(counter, count, &function);
347 if (err)
348 return err;
349
350 /* only set polarity when in counter mode (on input 1) */
351 if (function == STM32_LPTIM_COUNTER_INCREASE
352 && synapse->signal->id == count->synapses[0].signal->id) {
353 switch (action) {
354 case STM32_LPTIM_SYNAPSE_ACTION_RISING_EDGE:
355 case STM32_LPTIM_SYNAPSE_ACTION_FALLING_EDGE:
356 case STM32_LPTIM_SYNAPSE_ACTION_BOTH_EDGES:
357 priv->polarity = action;
358 return 0;
359 }
360 }
361
362 return -EINVAL;
363 }
364
365 static const struct counter_ops stm32_lptim_cnt_ops = {
366 .count_read = stm32_lptim_cnt_read,
367 .function_get = stm32_lptim_cnt_function_get,
368 .function_set = stm32_lptim_cnt_function_set,
369 .action_get = stm32_lptim_cnt_action_get,
370 .action_set = stm32_lptim_cnt_action_set,
371 };
372
373 static struct counter_signal stm32_lptim_cnt_signals[] = {
374 {
375 .id = 0,
376 .name = "Channel 1 Quadrature A"
377 },
378 {
379 .id = 1,
380 .name = "Channel 1 Quadrature B"
381 }
382 };
383
384 static struct counter_synapse stm32_lptim_cnt_synapses[] = {
385 {
386 .actions_list = stm32_lptim_cnt_synapse_actions,
387 .num_actions = ARRAY_SIZE(stm32_lptim_cnt_synapse_actions),
388 .signal = &stm32_lptim_cnt_signals[0]
389 },
390 {
391 .actions_list = stm32_lptim_cnt_synapse_actions,
392 .num_actions = ARRAY_SIZE(stm32_lptim_cnt_synapse_actions),
393 .signal = &stm32_lptim_cnt_signals[1]
394 }
395 };
396
397 /* LP timer with encoder */
398 static struct counter_count stm32_lptim_enc_counts = {
399 .id = 0,
400 .name = "LPTimer Count",
401 .functions_list = stm32_lptim_cnt_functions,
402 .num_functions = ARRAY_SIZE(stm32_lptim_cnt_functions),
403 .synapses = stm32_lptim_cnt_synapses,
404 .num_synapses = ARRAY_SIZE(stm32_lptim_cnt_synapses),
405 .ext = stm32_lptim_cnt_ext,
406 .num_ext = ARRAY_SIZE(stm32_lptim_cnt_ext)
407 };
408
409 /* LP timer without encoder (counter only) */
410 static struct counter_count stm32_lptim_in1_counts = {
411 .id = 0,
412 .name = "LPTimer Count",
413 .functions_list = stm32_lptim_cnt_functions,
414 .num_functions = 1,
415 .synapses = stm32_lptim_cnt_synapses,
416 .num_synapses = 1,
417 .ext = stm32_lptim_cnt_ext,
418 .num_ext = ARRAY_SIZE(stm32_lptim_cnt_ext)
419 };
420
stm32_lptim_cnt_probe(struct platform_device * pdev)421 static int stm32_lptim_cnt_probe(struct platform_device *pdev)
422 {
423 struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent);
424 struct stm32_lptim_cnt *priv;
425
426 if (IS_ERR_OR_NULL(ddata))
427 return -EINVAL;
428
429 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
430 if (!priv)
431 return -ENOMEM;
432
433 priv->dev = &pdev->dev;
434 priv->regmap = ddata->regmap;
435 priv->clk = ddata->clk;
436 priv->ceiling = STM32_LPTIM_MAX_ARR;
437
438 /* Initialize Counter device */
439 priv->counter.name = dev_name(&pdev->dev);
440 priv->counter.parent = &pdev->dev;
441 priv->counter.ops = &stm32_lptim_cnt_ops;
442 if (ddata->has_encoder) {
443 priv->counter.counts = &stm32_lptim_enc_counts;
444 priv->counter.num_signals = ARRAY_SIZE(stm32_lptim_cnt_signals);
445 } else {
446 priv->counter.counts = &stm32_lptim_in1_counts;
447 priv->counter.num_signals = 1;
448 }
449 priv->counter.num_counts = 1;
450 priv->counter.signals = stm32_lptim_cnt_signals;
451 priv->counter.priv = priv;
452
453 platform_set_drvdata(pdev, priv);
454
455 return devm_counter_register(&pdev->dev, &priv->counter);
456 }
457
458 #ifdef CONFIG_PM_SLEEP
stm32_lptim_cnt_suspend(struct device * dev)459 static int stm32_lptim_cnt_suspend(struct device *dev)
460 {
461 struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
462 int ret;
463
464 /* Only take care of enabled counter: don't disturb other MFD child */
465 if (priv->enabled) {
466 ret = stm32_lptim_setup(priv, 0);
467 if (ret)
468 return ret;
469
470 ret = stm32_lptim_set_enable_state(priv, 0);
471 if (ret)
472 return ret;
473
474 /* Force enable state for later resume */
475 priv->enabled = true;
476 }
477
478 return pinctrl_pm_select_sleep_state(dev);
479 }
480
stm32_lptim_cnt_resume(struct device * dev)481 static int stm32_lptim_cnt_resume(struct device *dev)
482 {
483 struct stm32_lptim_cnt *priv = dev_get_drvdata(dev);
484 int ret;
485
486 ret = pinctrl_pm_select_default_state(dev);
487 if (ret)
488 return ret;
489
490 if (priv->enabled) {
491 priv->enabled = false;
492 ret = stm32_lptim_setup(priv, 1);
493 if (ret)
494 return ret;
495
496 ret = stm32_lptim_set_enable_state(priv, 1);
497 if (ret)
498 return ret;
499 }
500
501 return 0;
502 }
503 #endif
504
505 static SIMPLE_DEV_PM_OPS(stm32_lptim_cnt_pm_ops, stm32_lptim_cnt_suspend,
506 stm32_lptim_cnt_resume);
507
508 static const struct of_device_id stm32_lptim_cnt_of_match[] = {
509 { .compatible = "st,stm32-lptimer-counter", },
510 {},
511 };
512 MODULE_DEVICE_TABLE(of, stm32_lptim_cnt_of_match);
513
514 static struct platform_driver stm32_lptim_cnt_driver = {
515 .probe = stm32_lptim_cnt_probe,
516 .driver = {
517 .name = "stm32-lptimer-counter",
518 .of_match_table = stm32_lptim_cnt_of_match,
519 .pm = &stm32_lptim_cnt_pm_ops,
520 },
521 };
522 module_platform_driver(stm32_lptim_cnt_driver);
523
524 MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
525 MODULE_ALIAS("platform:stm32-lptimer-counter");
526 MODULE_DESCRIPTION("STMicroelectronics STM32 LPTIM counter driver");
527 MODULE_LICENSE("GPL v2");
528