1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
4 *
5 * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
6 *
7 * Notes
8 * =====
9 * NXP LPC18xx provides a State Configurable Timer (SCT) which can be configured
10 * as a Pulse Width Modulator.
11 *
12 * SCT supports 16 outputs, 16 events and 16 registers. Each event will be
13 * triggered when its related register matches the SCT counter value, and it
14 * will set or clear a selected output.
15 *
16 * One of the events is preselected to generate the period, thus the maximum
17 * number of simultaneous channels is limited to 15. Notice that period is
18 * global to all the channels, thus PWM driver will refuse setting different
19 * values to it, unless there's only one channel requested.
20 */
21
22 #include <linux/clk.h>
23 #include <linux/err.h>
24 #include <linux/io.h>
25 #include <linux/mod_devicetable.h>
26 #include <linux/module.h>
27 #include <linux/platform_device.h>
28 #include <linux/pwm.h>
29
30 /* LPC18xx SCT registers */
31 #define LPC18XX_PWM_CONFIG 0x000
32 #define LPC18XX_PWM_CONFIG_UNIFY BIT(0)
33 #define LPC18XX_PWM_CONFIG_NORELOAD BIT(7)
34
35 #define LPC18XX_PWM_CTRL 0x004
36 #define LPC18XX_PWM_CTRL_HALT BIT(2)
37 #define LPC18XX_PWM_BIDIR BIT(4)
38 #define LPC18XX_PWM_PRE_SHIFT 5
39 #define LPC18XX_PWM_PRE_MASK (0xff << LPC18XX_PWM_PRE_SHIFT)
40 #define LPC18XX_PWM_PRE(x) (x << LPC18XX_PWM_PRE_SHIFT)
41
42 #define LPC18XX_PWM_LIMIT 0x008
43
44 #define LPC18XX_PWM_RES_BASE 0x058
45 #define LPC18XX_PWM_RES_SHIFT(_ch) (_ch * 2)
46 #define LPC18XX_PWM_RES(_ch, _action) (_action << LPC18XX_PWM_RES_SHIFT(_ch))
47 #define LPC18XX_PWM_RES_MASK(_ch) (0x3 << LPC18XX_PWM_RES_SHIFT(_ch))
48
49 #define LPC18XX_PWM_MATCH_BASE 0x100
50 #define LPC18XX_PWM_MATCH(_ch) (LPC18XX_PWM_MATCH_BASE + _ch * 4)
51
52 #define LPC18XX_PWM_MATCHREL_BASE 0x200
53 #define LPC18XX_PWM_MATCHREL(_ch) (LPC18XX_PWM_MATCHREL_BASE + _ch * 4)
54
55 #define LPC18XX_PWM_EVSTATEMSK_BASE 0x300
56 #define LPC18XX_PWM_EVSTATEMSK(_ch) (LPC18XX_PWM_EVSTATEMSK_BASE + _ch * 8)
57 #define LPC18XX_PWM_EVSTATEMSK_ALL 0xffffffff
58
59 #define LPC18XX_PWM_EVCTRL_BASE 0x304
60 #define LPC18XX_PWM_EVCTRL(_ev) (LPC18XX_PWM_EVCTRL_BASE + _ev * 8)
61
62 #define LPC18XX_PWM_EVCTRL_MATCH(_ch) _ch
63
64 #define LPC18XX_PWM_EVCTRL_COMB_SHIFT 12
65 #define LPC18XX_PWM_EVCTRL_COMB_MATCH (0x1 << LPC18XX_PWM_EVCTRL_COMB_SHIFT)
66
67 #define LPC18XX_PWM_OUTPUTSET_BASE 0x500
68 #define LPC18XX_PWM_OUTPUTSET(_ch) (LPC18XX_PWM_OUTPUTSET_BASE + _ch * 8)
69
70 #define LPC18XX_PWM_OUTPUTCL_BASE 0x504
71 #define LPC18XX_PWM_OUTPUTCL(_ch) (LPC18XX_PWM_OUTPUTCL_BASE + _ch * 8)
72
73 /* LPC18xx SCT unified counter */
74 #define LPC18XX_PWM_TIMER_MAX 0xffffffff
75
76 /* LPC18xx SCT events */
77 #define LPC18XX_PWM_EVENT_PERIOD 0
78 #define LPC18XX_PWM_EVENT_MAX 16
79
80 #define LPC18XX_NUM_PWMS 16
81
82 /* SCT conflict resolution */
83 enum lpc18xx_pwm_res_action {
84 LPC18XX_PWM_RES_NONE,
85 LPC18XX_PWM_RES_SET,
86 LPC18XX_PWM_RES_CLEAR,
87 LPC18XX_PWM_RES_TOGGLE,
88 };
89
90 struct lpc18xx_pwm_data {
91 unsigned int duty_event;
92 };
93
94 struct lpc18xx_pwm_chip {
95 void __iomem *base;
96 struct clk *pwm_clk;
97 unsigned long clk_rate;
98 unsigned int period_ns;
99 unsigned int min_period_ns;
100 u64 max_period_ns;
101 unsigned int period_event;
102 unsigned long event_map;
103 struct mutex res_lock;
104 struct mutex period_lock;
105 struct lpc18xx_pwm_data channeldata[LPC18XX_NUM_PWMS];
106 };
107
108 static inline struct lpc18xx_pwm_chip *
to_lpc18xx_pwm_chip(struct pwm_chip * chip)109 to_lpc18xx_pwm_chip(struct pwm_chip *chip)
110 {
111 return pwmchip_get_drvdata(chip);
112 }
113
lpc18xx_pwm_writel(struct lpc18xx_pwm_chip * lpc18xx_pwm,u32 reg,u32 val)114 static inline void lpc18xx_pwm_writel(struct lpc18xx_pwm_chip *lpc18xx_pwm,
115 u32 reg, u32 val)
116 {
117 writel(val, lpc18xx_pwm->base + reg);
118 }
119
lpc18xx_pwm_readl(struct lpc18xx_pwm_chip * lpc18xx_pwm,u32 reg)120 static inline u32 lpc18xx_pwm_readl(struct lpc18xx_pwm_chip *lpc18xx_pwm,
121 u32 reg)
122 {
123 return readl(lpc18xx_pwm->base + reg);
124 }
125
lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip * lpc18xx_pwm,struct pwm_device * pwm,enum lpc18xx_pwm_res_action action)126 static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
127 struct pwm_device *pwm,
128 enum lpc18xx_pwm_res_action action)
129 {
130 u32 val;
131
132 mutex_lock(&lpc18xx_pwm->res_lock);
133
134 /*
135 * Simultaneous set and clear may happen on an output, that is the case
136 * when duty_ns == period_ns. LPC18xx SCT allows to set a conflict
137 * resolution action to be taken in such a case.
138 */
139 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_RES_BASE);
140 val &= ~LPC18XX_PWM_RES_MASK(pwm->hwpwm);
141 val |= LPC18XX_PWM_RES(pwm->hwpwm, action);
142 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_RES_BASE, val);
143
144 mutex_unlock(&lpc18xx_pwm->res_lock);
145 }
146
lpc18xx_pwm_config_period(struct pwm_chip * chip,u64 period_ns)147 static void lpc18xx_pwm_config_period(struct pwm_chip *chip, u64 period_ns)
148 {
149 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
150 u32 val;
151
152 /*
153 * With clk_rate < NSEC_PER_SEC this cannot overflow.
154 * With period_ns < max_period_ns this also fits into an u32.
155 * As period_ns >= min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC, lpc18xx_pwm->clk_rate);
156 * we have val >= 1.
157 */
158 val = mul_u64_u64_div_u64(period_ns, lpc18xx_pwm->clk_rate, NSEC_PER_SEC);
159
160 lpc18xx_pwm_writel(lpc18xx_pwm,
161 LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
162 val - 1);
163
164 lpc18xx_pwm_writel(lpc18xx_pwm,
165 LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
166 val - 1);
167 }
168
lpc18xx_pwm_config_duty(struct pwm_chip * chip,struct pwm_device * pwm,u64 duty_ns)169 static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
170 struct pwm_device *pwm, u64 duty_ns)
171 {
172 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
173 struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
174 u32 val;
175
176 /*
177 * With clk_rate <= NSEC_PER_SEC this cannot overflow.
178 * With duty_ns <= period_ns < max_period_ns this also fits into an u32.
179 */
180 val = mul_u64_u64_div_u64(duty_ns, lpc18xx_pwm->clk_rate, NSEC_PER_SEC);
181
182 lpc18xx_pwm_writel(lpc18xx_pwm,
183 LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
184 val);
185
186 lpc18xx_pwm_writel(lpc18xx_pwm,
187 LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
188 val);
189 }
190
lpc18xx_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)191 static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
192 int duty_ns, int period_ns)
193 {
194 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
195 int requested_events;
196
197 if (period_ns < lpc18xx_pwm->min_period_ns ||
198 period_ns > lpc18xx_pwm->max_period_ns) {
199 dev_err(pwmchip_parent(chip), "period %d not in range\n", period_ns);
200 return -ERANGE;
201 }
202
203 mutex_lock(&lpc18xx_pwm->period_lock);
204
205 requested_events = bitmap_weight(&lpc18xx_pwm->event_map,
206 LPC18XX_PWM_EVENT_MAX);
207
208 /*
209 * The PWM supports only a single period for all PWM channels.
210 * Once the period is set, it can only be changed if no more than one
211 * channel is requested at that moment.
212 */
213 if (requested_events > 2 && lpc18xx_pwm->period_ns != period_ns &&
214 lpc18xx_pwm->period_ns) {
215 dev_err(pwmchip_parent(chip), "conflicting period requested for PWM %u\n",
216 pwm->hwpwm);
217 mutex_unlock(&lpc18xx_pwm->period_lock);
218 return -EBUSY;
219 }
220
221 if ((requested_events <= 2 && lpc18xx_pwm->period_ns != period_ns) ||
222 !lpc18xx_pwm->period_ns) {
223 lpc18xx_pwm->period_ns = period_ns;
224 lpc18xx_pwm_config_period(chip, period_ns);
225 }
226
227 mutex_unlock(&lpc18xx_pwm->period_lock);
228
229 lpc18xx_pwm_config_duty(chip, pwm, duty_ns);
230
231 return 0;
232 }
233
lpc18xx_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)234 static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm, enum pwm_polarity polarity)
235 {
236 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
237 struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
238 enum lpc18xx_pwm_res_action res_action;
239 unsigned int set_event, clear_event;
240
241 lpc18xx_pwm_writel(lpc18xx_pwm,
242 LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event),
243 LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_data->duty_event) |
244 LPC18XX_PWM_EVCTRL_COMB_MATCH);
245
246 lpc18xx_pwm_writel(lpc18xx_pwm,
247 LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
248 LPC18XX_PWM_EVSTATEMSK_ALL);
249
250 if (polarity == PWM_POLARITY_NORMAL) {
251 set_event = lpc18xx_pwm->period_event;
252 clear_event = lpc18xx_data->duty_event;
253 res_action = LPC18XX_PWM_RES_SET;
254 } else {
255 set_event = lpc18xx_data->duty_event;
256 clear_event = lpc18xx_pwm->period_event;
257 res_action = LPC18XX_PWM_RES_CLEAR;
258 }
259
260 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm),
261 BIT(set_event));
262 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm),
263 BIT(clear_event));
264 lpc18xx_pwm_set_conflict_res(lpc18xx_pwm, pwm, res_action);
265
266 return 0;
267 }
268
lpc18xx_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)269 static void lpc18xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
270 {
271 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
272 struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
273
274 lpc18xx_pwm_writel(lpc18xx_pwm,
275 LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event), 0);
276 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm), 0);
277 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm), 0);
278 }
279
lpc18xx_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)280 static int lpc18xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
281 {
282 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
283 struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
284 unsigned long event;
285
286 event = find_first_zero_bit(&lpc18xx_pwm->event_map,
287 LPC18XX_PWM_EVENT_MAX);
288
289 if (event >= LPC18XX_PWM_EVENT_MAX) {
290 dev_err(pwmchip_parent(chip),
291 "maximum number of simultaneous channels reached\n");
292 return -EBUSY;
293 }
294
295 set_bit(event, &lpc18xx_pwm->event_map);
296 lpc18xx_data->duty_event = event;
297
298 return 0;
299 }
300
lpc18xx_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)301 static void lpc18xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
302 {
303 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
304 struct lpc18xx_pwm_data *lpc18xx_data = &lpc18xx_pwm->channeldata[pwm->hwpwm];
305
306 clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
307 }
308
lpc18xx_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)309 static int lpc18xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
310 const struct pwm_state *state)
311 {
312 int err;
313 bool enabled = pwm->state.enabled;
314
315 if (state->polarity != pwm->state.polarity && pwm->state.enabled) {
316 lpc18xx_pwm_disable(chip, pwm);
317 enabled = false;
318 }
319
320 if (!state->enabled) {
321 if (enabled)
322 lpc18xx_pwm_disable(chip, pwm);
323
324 return 0;
325 }
326
327 err = lpc18xx_pwm_config(chip, pwm, state->duty_cycle, state->period);
328 if (err)
329 return err;
330
331 if (!enabled)
332 err = lpc18xx_pwm_enable(chip, pwm, state->polarity);
333
334 return err;
335 }
336 static const struct pwm_ops lpc18xx_pwm_ops = {
337 .apply = lpc18xx_pwm_apply,
338 .request = lpc18xx_pwm_request,
339 .free = lpc18xx_pwm_free,
340 };
341
342 static const struct of_device_id lpc18xx_pwm_of_match[] = {
343 { .compatible = "nxp,lpc1850-sct-pwm" },
344 {}
345 };
346 MODULE_DEVICE_TABLE(of, lpc18xx_pwm_of_match);
347
lpc18xx_pwm_probe(struct platform_device * pdev)348 static int lpc18xx_pwm_probe(struct platform_device *pdev)
349 {
350 struct pwm_chip *chip;
351 struct lpc18xx_pwm_chip *lpc18xx_pwm;
352 int ret;
353 u64 val;
354
355 chip = devm_pwmchip_alloc(&pdev->dev, LPC18XX_NUM_PWMS, sizeof(*lpc18xx_pwm));
356 if (IS_ERR(chip))
357 return PTR_ERR(chip);
358 lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
359
360 lpc18xx_pwm->base = devm_platform_ioremap_resource(pdev, 0);
361 if (IS_ERR(lpc18xx_pwm->base))
362 return PTR_ERR(lpc18xx_pwm->base);
363
364 lpc18xx_pwm->pwm_clk = devm_clk_get_enabled(&pdev->dev, "pwm");
365 if (IS_ERR(lpc18xx_pwm->pwm_clk))
366 return dev_err_probe(&pdev->dev, PTR_ERR(lpc18xx_pwm->pwm_clk),
367 "failed to get pwm clock\n");
368
369 lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
370 if (!lpc18xx_pwm->clk_rate)
371 return dev_err_probe(&pdev->dev,
372 -EINVAL, "pwm clock has no frequency\n");
373
374 /*
375 * If clkrate is too fast, the calculations in .apply() might overflow.
376 */
377 if (lpc18xx_pwm->clk_rate > NSEC_PER_SEC)
378 return dev_err_probe(&pdev->dev, -EINVAL, "pwm clock to fast\n");
379
380 mutex_init(&lpc18xx_pwm->res_lock);
381 mutex_init(&lpc18xx_pwm->period_lock);
382
383 lpc18xx_pwm->max_period_ns =
384 mul_u64_u64_div_u64(NSEC_PER_SEC, LPC18XX_PWM_TIMER_MAX, lpc18xx_pwm->clk_rate);
385
386 lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
387 lpc18xx_pwm->clk_rate);
388
389 chip->ops = &lpc18xx_pwm_ops;
390
391 /* SCT counter must be in unify (32 bit) mode */
392 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG,
393 LPC18XX_PWM_CONFIG_UNIFY);
394
395 /*
396 * Everytime the timer counter reaches the period value, the related
397 * event will be triggered and the counter reset to 0.
398 */
399 set_bit(LPC18XX_PWM_EVENT_PERIOD, &lpc18xx_pwm->event_map);
400 lpc18xx_pwm->period_event = LPC18XX_PWM_EVENT_PERIOD;
401
402 lpc18xx_pwm_writel(lpc18xx_pwm,
403 LPC18XX_PWM_EVSTATEMSK(lpc18xx_pwm->period_event),
404 LPC18XX_PWM_EVSTATEMSK_ALL);
405
406 val = LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_pwm->period_event) |
407 LPC18XX_PWM_EVCTRL_COMB_MATCH;
408 lpc18xx_pwm_writel(lpc18xx_pwm,
409 LPC18XX_PWM_EVCTRL(lpc18xx_pwm->period_event), val);
410
411 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
412 BIT(lpc18xx_pwm->period_event));
413
414 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
415 val &= ~LPC18XX_PWM_BIDIR;
416 val &= ~LPC18XX_PWM_CTRL_HALT;
417 val &= ~LPC18XX_PWM_PRE_MASK;
418 val |= LPC18XX_PWM_PRE(0);
419 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);
420
421 ret = pwmchip_add(chip);
422 if (ret < 0)
423 return dev_err_probe(&pdev->dev, ret, "pwmchip_add failed\n");
424
425 platform_set_drvdata(pdev, chip);
426
427 return 0;
428 }
429
lpc18xx_pwm_remove(struct platform_device * pdev)430 static void lpc18xx_pwm_remove(struct platform_device *pdev)
431 {
432 struct pwm_chip *chip = platform_get_drvdata(pdev);
433 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
434 u32 val;
435
436 pwmchip_remove(chip);
437
438 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
439 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL,
440 val | LPC18XX_PWM_CTRL_HALT);
441 }
442
443 static struct platform_driver lpc18xx_pwm_driver = {
444 .driver = {
445 .name = "lpc18xx-sct-pwm",
446 .of_match_table = lpc18xx_pwm_of_match,
447 },
448 .probe = lpc18xx_pwm_probe,
449 .remove = lpc18xx_pwm_remove,
450 };
451 module_platform_driver(lpc18xx_pwm_driver);
452
453 MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
454 MODULE_DESCRIPTION("NXP LPC18xx PWM driver");
455 MODULE_LICENSE("GPL v2");
456