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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/module.h>
26#include <linux/platform_device.h>
27#include <linux/pwm.h>
28
29/* LPC18xx SCT registers */
30#define LPC18XX_PWM_CONFIG 0x000
31#define LPC18XX_PWM_CONFIG_UNIFY BIT(0)
32#define LPC18XX_PWM_CONFIG_NORELOAD BIT(7)
33
34#define LPC18XX_PWM_CTRL 0x004
35#define LPC18XX_PWM_CTRL_HALT BIT(2)
36#define LPC18XX_PWM_BIDIR BIT(4)
37#define LPC18XX_PWM_PRE_SHIFT 5
38#define LPC18XX_PWM_PRE_MASK (0xff << LPC18XX_PWM_PRE_SHIFT)
39#define LPC18XX_PWM_PRE(x) (x << LPC18XX_PWM_PRE_SHIFT)
40
41#define LPC18XX_PWM_LIMIT 0x008
42
43#define LPC18XX_PWM_RES_BASE 0x058
44#define LPC18XX_PWM_RES_SHIFT(_ch) (_ch * 2)
45#define LPC18XX_PWM_RES(_ch, _action) (_action << LPC18XX_PWM_RES_SHIFT(_ch))
46#define LPC18XX_PWM_RES_MASK(_ch) (0x3 << LPC18XX_PWM_RES_SHIFT(_ch))
47
48#define LPC18XX_PWM_MATCH_BASE 0x100
49#define LPC18XX_PWM_MATCH(_ch) (LPC18XX_PWM_MATCH_BASE + _ch * 4)
50
51#define LPC18XX_PWM_MATCHREL_BASE 0x200
52#define LPC18XX_PWM_MATCHREL(_ch) (LPC18XX_PWM_MATCHREL_BASE + _ch * 4)
53
54#define LPC18XX_PWM_EVSTATEMSK_BASE 0x300
55#define LPC18XX_PWM_EVSTATEMSK(_ch) (LPC18XX_PWM_EVSTATEMSK_BASE + _ch * 8)
56#define LPC18XX_PWM_EVSTATEMSK_ALL 0xffffffff
57
58#define LPC18XX_PWM_EVCTRL_BASE 0x304
59#define LPC18XX_PWM_EVCTRL(_ev) (LPC18XX_PWM_EVCTRL_BASE + _ev * 8)
60
61#define LPC18XX_PWM_EVCTRL_MATCH(_ch) _ch
62
63#define LPC18XX_PWM_EVCTRL_COMB_SHIFT 12
64#define LPC18XX_PWM_EVCTRL_COMB_MATCH (0x1 << LPC18XX_PWM_EVCTRL_COMB_SHIFT)
65
66#define LPC18XX_PWM_OUTPUTSET_BASE 0x500
67#define LPC18XX_PWM_OUTPUTSET(_ch) (LPC18XX_PWM_OUTPUTSET_BASE + _ch * 8)
68
69#define LPC18XX_PWM_OUTPUTCL_BASE 0x504
70#define LPC18XX_PWM_OUTPUTCL(_ch) (LPC18XX_PWM_OUTPUTCL_BASE + _ch * 8)
71
72/* LPC18xx SCT unified counter */
73#define LPC18XX_PWM_TIMER_MAX 0xffffffff
74
75/* LPC18xx SCT events */
76#define LPC18XX_PWM_EVENT_PERIOD 0
77#define LPC18XX_PWM_EVENT_MAX 16
78
79/* SCT conflict resolution */
80enum lpc18xx_pwm_res_action {
81 LPC18XX_PWM_RES_NONE,
82 LPC18XX_PWM_RES_SET,
83 LPC18XX_PWM_RES_CLEAR,
84 LPC18XX_PWM_RES_TOGGLE,
85};
86
87struct lpc18xx_pwm_data {
88 unsigned int duty_event;
89};
90
91struct lpc18xx_pwm_chip {
92 struct device *dev;
93 struct pwm_chip chip;
94 void __iomem *base;
95 struct clk *pwm_clk;
96 unsigned long clk_rate;
97 unsigned int period_ns;
98 unsigned int min_period_ns;
99 unsigned int max_period_ns;
100 unsigned int period_event;
101 unsigned long event_map;
102 struct mutex res_lock;
103 struct mutex period_lock;
104};
105
106static inline struct lpc18xx_pwm_chip *
107to_lpc18xx_pwm_chip(struct pwm_chip *chip)
108{
109 return container_of(chip, struct lpc18xx_pwm_chip, chip);
110}
111
112static inline void lpc18xx_pwm_writel(struct lpc18xx_pwm_chip *lpc18xx_pwm,
113 u32 reg, u32 val)
114{
115 writel(val, lpc18xx_pwm->base + reg);
116}
117
118static inline u32 lpc18xx_pwm_readl(struct lpc18xx_pwm_chip *lpc18xx_pwm,
119 u32 reg)
120{
121 return readl(lpc18xx_pwm->base + reg);
122}
123
124static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
125 struct pwm_device *pwm,
126 enum lpc18xx_pwm_res_action action)
127{
128 u32 val;
129
130 mutex_lock(&lpc18xx_pwm->res_lock);
131
132 /*
133 * Simultaneous set and clear may happen on an output, that is the case
134 * when duty_ns == period_ns. LPC18xx SCT allows to set a conflict
135 * resolution action to be taken in such a case.
136 */
137 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_RES_BASE);
138 val &= ~LPC18XX_PWM_RES_MASK(pwm->hwpwm);
139 val |= LPC18XX_PWM_RES(pwm->hwpwm, action);
140 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_RES_BASE, val);
141
142 mutex_unlock(&lpc18xx_pwm->res_lock);
143}
144
145static void lpc18xx_pwm_config_period(struct pwm_chip *chip, int period_ns)
146{
147 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
148 u64 val;
149
150 val = (u64)period_ns * lpc18xx_pwm->clk_rate;
151 do_div(val, NSEC_PER_SEC);
152
153 lpc18xx_pwm_writel(lpc18xx_pwm,
154 LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
155 (u32)val - 1);
156
157 lpc18xx_pwm_writel(lpc18xx_pwm,
158 LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
159 (u32)val - 1);
160}
161
162static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
163 struct pwm_device *pwm, int duty_ns)
164{
165 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
166 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
167 u64 val;
168
169 val = (u64)duty_ns * lpc18xx_pwm->clk_rate;
170 do_div(val, NSEC_PER_SEC);
171
172 lpc18xx_pwm_writel(lpc18xx_pwm,
173 LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
174 (u32)val);
175
176 lpc18xx_pwm_writel(lpc18xx_pwm,
177 LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
178 (u32)val);
179}
180
181static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
182 int duty_ns, int period_ns)
183{
184 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
185 int requested_events, i;
186
187 if (period_ns < lpc18xx_pwm->min_period_ns ||
188 period_ns > lpc18xx_pwm->max_period_ns) {
189 dev_err(chip->dev, "period %d not in range\n", period_ns);
190 return -ERANGE;
191 }
192
193 mutex_lock(&lpc18xx_pwm->period_lock);
194
195 requested_events = bitmap_weight(&lpc18xx_pwm->event_map,
196 LPC18XX_PWM_EVENT_MAX);
197
198 /*
199 * The PWM supports only a single period for all PWM channels.
200 * Once the period is set, it can only be changed if no more than one
201 * channel is requested at that moment.
202 */
203 if (requested_events > 2 && lpc18xx_pwm->period_ns != period_ns &&
204 lpc18xx_pwm->period_ns) {
205 dev_err(chip->dev, "conflicting period requested for PWM %u\n",
206 pwm->hwpwm);
207 mutex_unlock(&lpc18xx_pwm->period_lock);
208 return -EBUSY;
209 }
210
211 if ((requested_events <= 2 && lpc18xx_pwm->period_ns != period_ns) ||
212 !lpc18xx_pwm->period_ns) {
213 lpc18xx_pwm->period_ns = period_ns;
214 for (i = 0; i < chip->npwm; i++)
215 pwm_set_period(&chip->pwms[i], period_ns);
216 lpc18xx_pwm_config_period(chip, period_ns);
217 }
218
219 mutex_unlock(&lpc18xx_pwm->period_lock);
220
221 lpc18xx_pwm_config_duty(chip, pwm, duty_ns);
222
223 return 0;
224}
225
226static int lpc18xx_pwm_set_polarity(struct pwm_chip *chip,
227 struct pwm_device *pwm,
228 enum pwm_polarity polarity)
229{
230 return 0;
231}
232
233static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
234{
235 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
236 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
237 enum lpc18xx_pwm_res_action res_action;
238 unsigned int set_event, clear_event;
239
240 lpc18xx_pwm_writel(lpc18xx_pwm,
241 LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event),
242 LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_data->duty_event) |
243 LPC18XX_PWM_EVCTRL_COMB_MATCH);
244
245 lpc18xx_pwm_writel(lpc18xx_pwm,
246 LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
247 LPC18XX_PWM_EVSTATEMSK_ALL);
248
249 if (pwm_get_polarity(pwm) == PWM_POLARITY_NORMAL) {
250 set_event = lpc18xx_pwm->period_event;
251 clear_event = lpc18xx_data->duty_event;
252 res_action = LPC18XX_PWM_RES_SET;
253 } else {
254 set_event = lpc18xx_data->duty_event;
255 clear_event = lpc18xx_pwm->period_event;
256 res_action = LPC18XX_PWM_RES_CLEAR;
257 }
258
259 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm),
260 BIT(set_event));
261 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm),
262 BIT(clear_event));
263 lpc18xx_pwm_set_conflict_res(lpc18xx_pwm, pwm, res_action);
264
265 return 0;
266}
267
268static void lpc18xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
269{
270 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
271 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
272
273 lpc18xx_pwm_writel(lpc18xx_pwm,
274 LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event), 0);
275 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm), 0);
276 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm), 0);
277}
278
279static int lpc18xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
280{
281 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
282 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
283 unsigned long event;
284
285 event = find_first_zero_bit(&lpc18xx_pwm->event_map,
286 LPC18XX_PWM_EVENT_MAX);
287
288 if (event >= LPC18XX_PWM_EVENT_MAX) {
289 dev_err(lpc18xx_pwm->dev,
290 "maximum number of simultaneous channels reached\n");
291 return -EBUSY;
292 };
293
294 set_bit(event, &lpc18xx_pwm->event_map);
295 lpc18xx_data->duty_event = event;
296
297 return 0;
298}
299
300static void lpc18xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
301{
302 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
303 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
304
305 clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
306}
307
308static const struct pwm_ops lpc18xx_pwm_ops = {
309 .config = lpc18xx_pwm_config,
310 .set_polarity = lpc18xx_pwm_set_polarity,
311 .enable = lpc18xx_pwm_enable,
312 .disable = lpc18xx_pwm_disable,
313 .request = lpc18xx_pwm_request,
314 .free = lpc18xx_pwm_free,
315 .owner = THIS_MODULE,
316};
317
318static const struct of_device_id lpc18xx_pwm_of_match[] = {
319 { .compatible = "nxp,lpc1850-sct-pwm" },
320 {}
321};
322MODULE_DEVICE_TABLE(of, lpc18xx_pwm_of_match);
323
324static int lpc18xx_pwm_probe(struct platform_device *pdev)
325{
326 struct lpc18xx_pwm_chip *lpc18xx_pwm;
327 struct pwm_device *pwm;
328 struct resource *res;
329 int ret, i;
330 u64 val;
331
332 lpc18xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*lpc18xx_pwm),
333 GFP_KERNEL);
334 if (!lpc18xx_pwm)
335 return -ENOMEM;
336
337 lpc18xx_pwm->dev = &pdev->dev;
338
339 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
340 lpc18xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
341 if (IS_ERR(lpc18xx_pwm->base))
342 return PTR_ERR(lpc18xx_pwm->base);
343
344 lpc18xx_pwm->pwm_clk = devm_clk_get(&pdev->dev, "pwm");
345 if (IS_ERR(lpc18xx_pwm->pwm_clk)) {
346 dev_err(&pdev->dev, "failed to get pwm clock\n");
347 return PTR_ERR(lpc18xx_pwm->pwm_clk);
348 }
349
350 ret = clk_prepare_enable(lpc18xx_pwm->pwm_clk);
351 if (ret < 0) {
352 dev_err(&pdev->dev, "could not prepare or enable pwm clock\n");
353 return ret;
354 }
355
356 lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
357 if (!lpc18xx_pwm->clk_rate) {
358 dev_err(&pdev->dev, "pwm clock has no frequency\n");
359 ret = -EINVAL;
360 goto disable_pwmclk;
361 }
362
363 mutex_init(&lpc18xx_pwm->res_lock);
364 mutex_init(&lpc18xx_pwm->period_lock);
365
366 val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX;
367 do_div(val, lpc18xx_pwm->clk_rate);
368 lpc18xx_pwm->max_period_ns = val;
369
370 lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
371 lpc18xx_pwm->clk_rate);
372
373 lpc18xx_pwm->chip.dev = &pdev->dev;
374 lpc18xx_pwm->chip.ops = &lpc18xx_pwm_ops;
375 lpc18xx_pwm->chip.base = -1;
376 lpc18xx_pwm->chip.npwm = 16;
377 lpc18xx_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
378 lpc18xx_pwm->chip.of_pwm_n_cells = 3;
379
380 /* SCT counter must be in unify (32 bit) mode */
381 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG,
382 LPC18XX_PWM_CONFIG_UNIFY);
383
384 /*
385 * Everytime the timer counter reaches the period value, the related
386 * event will be triggered and the counter reset to 0.
387 */
388 set_bit(LPC18XX_PWM_EVENT_PERIOD, &lpc18xx_pwm->event_map);
389 lpc18xx_pwm->period_event = LPC18XX_PWM_EVENT_PERIOD;
390
391 lpc18xx_pwm_writel(lpc18xx_pwm,
392 LPC18XX_PWM_EVSTATEMSK(lpc18xx_pwm->period_event),
393 LPC18XX_PWM_EVSTATEMSK_ALL);
394
395 val = LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_pwm->period_event) |
396 LPC18XX_PWM_EVCTRL_COMB_MATCH;
397 lpc18xx_pwm_writel(lpc18xx_pwm,
398 LPC18XX_PWM_EVCTRL(lpc18xx_pwm->period_event), val);
399
400 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
401 BIT(lpc18xx_pwm->period_event));
402
403 ret = pwmchip_add(&lpc18xx_pwm->chip);
404 if (ret < 0) {
405 dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
406 goto disable_pwmclk;
407 }
408
409 for (i = 0; i < lpc18xx_pwm->chip.npwm; i++) {
410 struct lpc18xx_pwm_data *data;
411
412 pwm = &lpc18xx_pwm->chip.pwms[i];
413
414 data = devm_kzalloc(lpc18xx_pwm->dev, sizeof(*data),
415 GFP_KERNEL);
416 if (!data) {
417 ret = -ENOMEM;
418 goto remove_pwmchip;
419 }
420
421 pwm_set_chip_data(pwm, data);
422 }
423
424 platform_set_drvdata(pdev, lpc18xx_pwm);
425
426 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
427 val &= ~LPC18XX_PWM_BIDIR;
428 val &= ~LPC18XX_PWM_CTRL_HALT;
429 val &= ~LPC18XX_PWM_PRE_MASK;
430 val |= LPC18XX_PWM_PRE(0);
431 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);
432
433 return 0;
434
435remove_pwmchip:
436 pwmchip_remove(&lpc18xx_pwm->chip);
437disable_pwmclk:
438 clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
439 return ret;
440}
441
442static int lpc18xx_pwm_remove(struct platform_device *pdev)
443{
444 struct lpc18xx_pwm_chip *lpc18xx_pwm = platform_get_drvdata(pdev);
445 u32 val;
446
447 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
448 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL,
449 val | LPC18XX_PWM_CTRL_HALT);
450
451 clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
452
453 return pwmchip_remove(&lpc18xx_pwm->chip);
454}
455
456static struct platform_driver lpc18xx_pwm_driver = {
457 .driver = {
458 .name = "lpc18xx-sct-pwm",
459 .of_match_table = lpc18xx_pwm_of_match,
460 },
461 .probe = lpc18xx_pwm_probe,
462 .remove = lpc18xx_pwm_remove,
463};
464module_platform_driver(lpc18xx_pwm_driver);
465
466MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
467MODULE_DESCRIPTION("NXP LPC18xx PWM driver");
468MODULE_LICENSE("GPL v2");