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1/*
2 * NXP LPC18xx State Configurable Timer - Pulse Width Modulator driver
3 *
4 * Copyright (c) 2015 Ariel D'Alessandro <ariel@vanguardiasur.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License.
9 *
10 * Notes
11 * =====
12 * NXP LPC18xx provides a State Configurable Timer (SCT) which can be configured
13 * as a Pulse Width Modulator.
14 *
15 * SCT supports 16 outputs, 16 events and 16 registers. Each event will be
16 * triggered when its related register matches the SCT counter value, and it
17 * will set or clear a selected output.
18 *
19 * One of the events is preselected to generate the period, thus the maximum
20 * number of simultaneous channels is limited to 15. Notice that period is
21 * global to all the channels, thus PWM driver will refuse setting different
22 * values to it, unless there's only one channel requested.
23 */
24
25#include <linux/clk.h>
26#include <linux/err.h>
27#include <linux/io.h>
28#include <linux/module.h>
29#include <linux/platform_device.h>
30#include <linux/pwm.h>
31
32/* LPC18xx SCT registers */
33#define LPC18XX_PWM_CONFIG 0x000
34#define LPC18XX_PWM_CONFIG_UNIFY BIT(0)
35#define LPC18XX_PWM_CONFIG_NORELOAD BIT(7)
36
37#define LPC18XX_PWM_CTRL 0x004
38#define LPC18XX_PWM_CTRL_HALT BIT(2)
39#define LPC18XX_PWM_BIDIR BIT(4)
40#define LPC18XX_PWM_PRE_SHIFT 5
41#define LPC18XX_PWM_PRE_MASK (0xff << LPC18XX_PWM_PRE_SHIFT)
42#define LPC18XX_PWM_PRE(x) (x << LPC18XX_PWM_PRE_SHIFT)
43
44#define LPC18XX_PWM_LIMIT 0x008
45
46#define LPC18XX_PWM_RES_BASE 0x058
47#define LPC18XX_PWM_RES_SHIFT(_ch) (_ch * 2)
48#define LPC18XX_PWM_RES(_ch, _action) (_action << LPC18XX_PWM_RES_SHIFT(_ch))
49#define LPC18XX_PWM_RES_MASK(_ch) (0x3 << LPC18XX_PWM_RES_SHIFT(_ch))
50
51#define LPC18XX_PWM_MATCH_BASE 0x100
52#define LPC18XX_PWM_MATCH(_ch) (LPC18XX_PWM_MATCH_BASE + _ch * 4)
53
54#define LPC18XX_PWM_MATCHREL_BASE 0x200
55#define LPC18XX_PWM_MATCHREL(_ch) (LPC18XX_PWM_MATCHREL_BASE + _ch * 4)
56
57#define LPC18XX_PWM_EVSTATEMSK_BASE 0x300
58#define LPC18XX_PWM_EVSTATEMSK(_ch) (LPC18XX_PWM_EVSTATEMSK_BASE + _ch * 8)
59#define LPC18XX_PWM_EVSTATEMSK_ALL 0xffffffff
60
61#define LPC18XX_PWM_EVCTRL_BASE 0x304
62#define LPC18XX_PWM_EVCTRL(_ev) (LPC18XX_PWM_EVCTRL_BASE + _ev * 8)
63
64#define LPC18XX_PWM_EVCTRL_MATCH(_ch) _ch
65
66#define LPC18XX_PWM_EVCTRL_COMB_SHIFT 12
67#define LPC18XX_PWM_EVCTRL_COMB_MATCH (0x1 << LPC18XX_PWM_EVCTRL_COMB_SHIFT)
68
69#define LPC18XX_PWM_OUTPUTSET_BASE 0x500
70#define LPC18XX_PWM_OUTPUTSET(_ch) (LPC18XX_PWM_OUTPUTSET_BASE + _ch * 8)
71
72#define LPC18XX_PWM_OUTPUTCL_BASE 0x504
73#define LPC18XX_PWM_OUTPUTCL(_ch) (LPC18XX_PWM_OUTPUTCL_BASE + _ch * 8)
74
75/* LPC18xx SCT unified counter */
76#define LPC18XX_PWM_TIMER_MAX 0xffffffff
77
78/* LPC18xx SCT events */
79#define LPC18XX_PWM_EVENT_PERIOD 0
80#define LPC18XX_PWM_EVENT_MAX 16
81
82/* SCT conflict resolution */
83enum 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
90struct lpc18xx_pwm_data {
91 unsigned int duty_event;
92};
93
94struct lpc18xx_pwm_chip {
95 struct device *dev;
96 struct pwm_chip chip;
97 void __iomem *base;
98 struct clk *pwm_clk;
99 unsigned long clk_rate;
100 unsigned int period_ns;
101 unsigned int min_period_ns;
102 unsigned int max_period_ns;
103 unsigned int period_event;
104 unsigned long event_map;
105 struct mutex res_lock;
106 struct mutex period_lock;
107};
108
109static inline struct lpc18xx_pwm_chip *
110to_lpc18xx_pwm_chip(struct pwm_chip *chip)
111{
112 return container_of(chip, struct lpc18xx_pwm_chip, chip);
113}
114
115static inline void lpc18xx_pwm_writel(struct lpc18xx_pwm_chip *lpc18xx_pwm,
116 u32 reg, u32 val)
117{
118 writel(val, lpc18xx_pwm->base + reg);
119}
120
121static inline u32 lpc18xx_pwm_readl(struct lpc18xx_pwm_chip *lpc18xx_pwm,
122 u32 reg)
123{
124 return readl(lpc18xx_pwm->base + reg);
125}
126
127static void lpc18xx_pwm_set_conflict_res(struct lpc18xx_pwm_chip *lpc18xx_pwm,
128 struct pwm_device *pwm,
129 enum lpc18xx_pwm_res_action action)
130{
131 u32 val;
132
133 mutex_lock(&lpc18xx_pwm->res_lock);
134
135 /*
136 * Simultaneous set and clear may happen on an output, that is the case
137 * when duty_ns == period_ns. LPC18xx SCT allows to set a conflict
138 * resolution action to be taken in such a case.
139 */
140 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_RES_BASE);
141 val &= ~LPC18XX_PWM_RES_MASK(pwm->hwpwm);
142 val |= LPC18XX_PWM_RES(pwm->hwpwm, action);
143 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_RES_BASE, val);
144
145 mutex_unlock(&lpc18xx_pwm->res_lock);
146}
147
148static void lpc18xx_pwm_config_period(struct pwm_chip *chip, int period_ns)
149{
150 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
151 u64 val;
152
153 val = (u64)period_ns * lpc18xx_pwm->clk_rate;
154 do_div(val, NSEC_PER_SEC);
155
156 lpc18xx_pwm_writel(lpc18xx_pwm,
157 LPC18XX_PWM_MATCH(lpc18xx_pwm->period_event),
158 (u32)val - 1);
159
160 lpc18xx_pwm_writel(lpc18xx_pwm,
161 LPC18XX_PWM_MATCHREL(lpc18xx_pwm->period_event),
162 (u32)val - 1);
163}
164
165static void lpc18xx_pwm_config_duty(struct pwm_chip *chip,
166 struct pwm_device *pwm, int duty_ns)
167{
168 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
169 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
170 u64 val;
171
172 val = (u64)duty_ns * lpc18xx_pwm->clk_rate;
173 do_div(val, NSEC_PER_SEC);
174
175 lpc18xx_pwm_writel(lpc18xx_pwm,
176 LPC18XX_PWM_MATCH(lpc18xx_data->duty_event),
177 (u32)val);
178
179 lpc18xx_pwm_writel(lpc18xx_pwm,
180 LPC18XX_PWM_MATCHREL(lpc18xx_data->duty_event),
181 (u32)val);
182}
183
184static int lpc18xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
185 int duty_ns, int period_ns)
186{
187 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
188 int requested_events, i;
189
190 if (period_ns < lpc18xx_pwm->min_period_ns ||
191 period_ns > lpc18xx_pwm->max_period_ns) {
192 dev_err(chip->dev, "period %d not in range\n", period_ns);
193 return -ERANGE;
194 }
195
196 mutex_lock(&lpc18xx_pwm->period_lock);
197
198 requested_events = bitmap_weight(&lpc18xx_pwm->event_map,
199 LPC18XX_PWM_EVENT_MAX);
200
201 /*
202 * The PWM supports only a single period for all PWM channels.
203 * Once the period is set, it can only be changed if no more than one
204 * channel is requested at that moment.
205 */
206 if (requested_events > 2 && lpc18xx_pwm->period_ns != period_ns &&
207 lpc18xx_pwm->period_ns) {
208 dev_err(chip->dev, "conflicting period requested for PWM %u\n",
209 pwm->hwpwm);
210 mutex_unlock(&lpc18xx_pwm->period_lock);
211 return -EBUSY;
212 }
213
214 if ((requested_events <= 2 && lpc18xx_pwm->period_ns != period_ns) ||
215 !lpc18xx_pwm->period_ns) {
216 lpc18xx_pwm->period_ns = period_ns;
217 for (i = 0; i < chip->npwm; i++)
218 pwm_set_period(&chip->pwms[i], period_ns);
219 lpc18xx_pwm_config_period(chip, period_ns);
220 }
221
222 mutex_unlock(&lpc18xx_pwm->period_lock);
223
224 lpc18xx_pwm_config_duty(chip, pwm, duty_ns);
225
226 return 0;
227}
228
229static int lpc18xx_pwm_set_polarity(struct pwm_chip *chip,
230 struct pwm_device *pwm,
231 enum pwm_polarity polarity)
232{
233 return 0;
234}
235
236static int lpc18xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
237{
238 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
239 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
240 enum lpc18xx_pwm_res_action res_action;
241 unsigned int set_event, clear_event;
242
243 lpc18xx_pwm_writel(lpc18xx_pwm,
244 LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event),
245 LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_data->duty_event) |
246 LPC18XX_PWM_EVCTRL_COMB_MATCH);
247
248 lpc18xx_pwm_writel(lpc18xx_pwm,
249 LPC18XX_PWM_EVSTATEMSK(lpc18xx_data->duty_event),
250 LPC18XX_PWM_EVSTATEMSK_ALL);
251
252 if (pwm->polarity == PWM_POLARITY_NORMAL) {
253 set_event = lpc18xx_pwm->period_event;
254 clear_event = lpc18xx_data->duty_event;
255 res_action = LPC18XX_PWM_RES_SET;
256 } else {
257 set_event = lpc18xx_data->duty_event;
258 clear_event = lpc18xx_pwm->period_event;
259 res_action = LPC18XX_PWM_RES_CLEAR;
260 }
261
262 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm),
263 BIT(set_event));
264 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm),
265 BIT(clear_event));
266 lpc18xx_pwm_set_conflict_res(lpc18xx_pwm, pwm, res_action);
267
268 return 0;
269}
270
271static void lpc18xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
272{
273 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
274 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
275
276 lpc18xx_pwm_writel(lpc18xx_pwm,
277 LPC18XX_PWM_EVCTRL(lpc18xx_data->duty_event), 0);
278 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTSET(pwm->hwpwm), 0);
279 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_OUTPUTCL(pwm->hwpwm), 0);
280}
281
282static int lpc18xx_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
283{
284 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
285 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
286 unsigned long event;
287
288 event = find_first_zero_bit(&lpc18xx_pwm->event_map,
289 LPC18XX_PWM_EVENT_MAX);
290
291 if (event >= LPC18XX_PWM_EVENT_MAX) {
292 dev_err(lpc18xx_pwm->dev,
293 "maximum number of simultaneous channels reached\n");
294 return -EBUSY;
295 };
296
297 set_bit(event, &lpc18xx_pwm->event_map);
298 lpc18xx_data->duty_event = event;
299 lpc18xx_pwm_config_duty(chip, pwm, pwm_get_duty_cycle(pwm));
300
301 return 0;
302}
303
304static void lpc18xx_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
305{
306 struct lpc18xx_pwm_chip *lpc18xx_pwm = to_lpc18xx_pwm_chip(chip);
307 struct lpc18xx_pwm_data *lpc18xx_data = pwm_get_chip_data(pwm);
308
309 pwm_disable(pwm);
310 pwm_set_duty_cycle(pwm, 0);
311 clear_bit(lpc18xx_data->duty_event, &lpc18xx_pwm->event_map);
312}
313
314static const struct pwm_ops lpc18xx_pwm_ops = {
315 .config = lpc18xx_pwm_config,
316 .set_polarity = lpc18xx_pwm_set_polarity,
317 .enable = lpc18xx_pwm_enable,
318 .disable = lpc18xx_pwm_disable,
319 .request = lpc18xx_pwm_request,
320 .free = lpc18xx_pwm_free,
321 .owner = THIS_MODULE,
322};
323
324static const struct of_device_id lpc18xx_pwm_of_match[] = {
325 { .compatible = "nxp,lpc1850-sct-pwm" },
326 {}
327};
328MODULE_DEVICE_TABLE(of, lpc18xx_pwm_of_match);
329
330static int lpc18xx_pwm_probe(struct platform_device *pdev)
331{
332 struct lpc18xx_pwm_chip *lpc18xx_pwm;
333 struct pwm_device *pwm;
334 struct resource *res;
335 int ret, i;
336 u64 val;
337
338 lpc18xx_pwm = devm_kzalloc(&pdev->dev, sizeof(*lpc18xx_pwm),
339 GFP_KERNEL);
340 if (!lpc18xx_pwm)
341 return -ENOMEM;
342
343 lpc18xx_pwm->dev = &pdev->dev;
344
345 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
346 lpc18xx_pwm->base = devm_ioremap_resource(&pdev->dev, res);
347 if (IS_ERR(lpc18xx_pwm->base))
348 return PTR_ERR(lpc18xx_pwm->base);
349
350 lpc18xx_pwm->pwm_clk = devm_clk_get(&pdev->dev, "pwm");
351 if (IS_ERR(lpc18xx_pwm->pwm_clk)) {
352 dev_err(&pdev->dev, "failed to get pwm clock\n");
353 return PTR_ERR(lpc18xx_pwm->pwm_clk);
354 }
355
356 ret = clk_prepare_enable(lpc18xx_pwm->pwm_clk);
357 if (ret < 0) {
358 dev_err(&pdev->dev, "could not prepare or enable pwm clock\n");
359 return ret;
360 }
361
362 lpc18xx_pwm->clk_rate = clk_get_rate(lpc18xx_pwm->pwm_clk);
363 if (!lpc18xx_pwm->clk_rate) {
364 dev_err(&pdev->dev, "pwm clock has no frequency\n");
365 ret = -EINVAL;
366 goto disable_pwmclk;
367 }
368
369 mutex_init(&lpc18xx_pwm->res_lock);
370 mutex_init(&lpc18xx_pwm->period_lock);
371
372 val = (u64)NSEC_PER_SEC * LPC18XX_PWM_TIMER_MAX;
373 do_div(val, lpc18xx_pwm->clk_rate);
374 lpc18xx_pwm->max_period_ns = val;
375
376 lpc18xx_pwm->min_period_ns = DIV_ROUND_UP(NSEC_PER_SEC,
377 lpc18xx_pwm->clk_rate);
378
379 lpc18xx_pwm->chip.dev = &pdev->dev;
380 lpc18xx_pwm->chip.ops = &lpc18xx_pwm_ops;
381 lpc18xx_pwm->chip.base = -1;
382 lpc18xx_pwm->chip.npwm = 16;
383 lpc18xx_pwm->chip.of_xlate = of_pwm_xlate_with_flags;
384 lpc18xx_pwm->chip.of_pwm_n_cells = 3;
385
386 /* SCT counter must be in unify (32 bit) mode */
387 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CONFIG,
388 LPC18XX_PWM_CONFIG_UNIFY);
389
390 /*
391 * Everytime the timer counter reaches the period value, the related
392 * event will be triggered and the counter reset to 0.
393 */
394 set_bit(LPC18XX_PWM_EVENT_PERIOD, &lpc18xx_pwm->event_map);
395 lpc18xx_pwm->period_event = LPC18XX_PWM_EVENT_PERIOD;
396
397 lpc18xx_pwm_writel(lpc18xx_pwm,
398 LPC18XX_PWM_EVSTATEMSK(lpc18xx_pwm->period_event),
399 LPC18XX_PWM_EVSTATEMSK_ALL);
400
401 val = LPC18XX_PWM_EVCTRL_MATCH(lpc18xx_pwm->period_event) |
402 LPC18XX_PWM_EVCTRL_COMB_MATCH;
403 lpc18xx_pwm_writel(lpc18xx_pwm,
404 LPC18XX_PWM_EVCTRL(lpc18xx_pwm->period_event), val);
405
406 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_LIMIT,
407 BIT(lpc18xx_pwm->period_event));
408
409 ret = pwmchip_add(&lpc18xx_pwm->chip);
410 if (ret < 0) {
411 dev_err(&pdev->dev, "pwmchip_add failed: %d\n", ret);
412 goto disable_pwmclk;
413 }
414
415 for (i = 0; i < lpc18xx_pwm->chip.npwm; i++) {
416 pwm = &lpc18xx_pwm->chip.pwms[i];
417 pwm->chip_data = devm_kzalloc(lpc18xx_pwm->dev,
418 sizeof(struct lpc18xx_pwm_data),
419 GFP_KERNEL);
420 if (!pwm->chip_data) {
421 ret = -ENOMEM;
422 goto remove_pwmchip;
423 }
424 }
425
426 platform_set_drvdata(pdev, lpc18xx_pwm);
427
428 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
429 val &= ~LPC18XX_PWM_BIDIR;
430 val &= ~LPC18XX_PWM_CTRL_HALT;
431 val &= ~LPC18XX_PWM_PRE_MASK;
432 val |= LPC18XX_PWM_PRE(0);
433 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL, val);
434
435 return 0;
436
437remove_pwmchip:
438 pwmchip_remove(&lpc18xx_pwm->chip);
439disable_pwmclk:
440 clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
441 return ret;
442}
443
444static int lpc18xx_pwm_remove(struct platform_device *pdev)
445{
446 struct lpc18xx_pwm_chip *lpc18xx_pwm = platform_get_drvdata(pdev);
447 u32 val;
448
449 val = lpc18xx_pwm_readl(lpc18xx_pwm, LPC18XX_PWM_CTRL);
450 lpc18xx_pwm_writel(lpc18xx_pwm, LPC18XX_PWM_CTRL,
451 val | LPC18XX_PWM_CTRL_HALT);
452
453 clk_disable_unprepare(lpc18xx_pwm->pwm_clk);
454
455 return pwmchip_remove(&lpc18xx_pwm->chip);
456}
457
458static struct platform_driver lpc18xx_pwm_driver = {
459 .driver = {
460 .name = "lpc18xx-sct-pwm",
461 .of_match_table = lpc18xx_pwm_of_match,
462 },
463 .probe = lpc18xx_pwm_probe,
464 .remove = lpc18xx_pwm_remove,
465};
466module_platform_driver(lpc18xx_pwm_driver);
467
468MODULE_AUTHOR("Ariel D'Alessandro <ariel@vanguardiasur.com.ar>");
469MODULE_DESCRIPTION("NXP LPC18xx PWM driver");
470MODULE_LICENSE("GPL v2");