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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Driver for Atmel Pulse Width Modulation Controller
4 *
5 * Copyright (C) 2013 Atmel Corporation
6 * Bo Shen <voice.shen@atmel.com>
7 *
8 * Links to reference manuals for the supported PWM chips can be found in
9 * Documentation/arm/microchip.rst.
10 *
11 * Limitations:
12 * - Periods start with the inactive level.
13 * - Hardware has to be stopped in general to update settings.
14 *
15 * Software bugs/possible improvements:
16 * - When atmel_pwm_apply() is called with state->enabled=false a change in
17 * state->polarity isn't honored.
18 * - Instead of sleeping to wait for a completed period, the interrupt
19 * functionality could be used.
20 */
21
22#include <linux/clk.h>
23#include <linux/delay.h>
24#include <linux/err.h>
25#include <linux/io.h>
26#include <linux/module.h>
27#include <linux/mutex.h>
28#include <linux/of.h>
29#include <linux/of_device.h>
30#include <linux/platform_device.h>
31#include <linux/pwm.h>
32#include <linux/slab.h>
33
34/* The following is global registers for PWM controller */
35#define PWM_ENA 0x04
36#define PWM_DIS 0x08
37#define PWM_SR 0x0C
38#define PWM_ISR 0x1C
39/* Bit field in SR */
40#define PWM_SR_ALL_CH_ON 0x0F
41
42/* The following register is PWM channel related registers */
43#define PWM_CH_REG_OFFSET 0x200
44#define PWM_CH_REG_SIZE 0x20
45
46#define PWM_CMR 0x0
47/* Bit field in CMR */
48#define PWM_CMR_CPOL (1 << 9)
49#define PWM_CMR_UPD_CDTY (1 << 10)
50#define PWM_CMR_CPRE_MSK 0xF
51
52/* The following registers for PWM v1 */
53#define PWMV1_CDTY 0x04
54#define PWMV1_CPRD 0x08
55#define PWMV1_CUPD 0x10
56
57/* The following registers for PWM v2 */
58#define PWMV2_CDTY 0x04
59#define PWMV2_CDTYUPD 0x08
60#define PWMV2_CPRD 0x0C
61#define PWMV2_CPRDUPD 0x10
62
63#define PWM_MAX_PRES 10
64
65struct atmel_pwm_registers {
66 u8 period;
67 u8 period_upd;
68 u8 duty;
69 u8 duty_upd;
70};
71
72struct atmel_pwm_config {
73 u32 period_bits;
74};
75
76struct atmel_pwm_data {
77 struct atmel_pwm_registers regs;
78 struct atmel_pwm_config cfg;
79};
80
81struct atmel_pwm_chip {
82 struct pwm_chip chip;
83 struct clk *clk;
84 void __iomem *base;
85 const struct atmel_pwm_data *data;
86
87 unsigned int updated_pwms;
88 /* ISR is cleared when read, ensure only one thread does that */
89 struct mutex isr_lock;
90};
91
92static inline struct atmel_pwm_chip *to_atmel_pwm_chip(struct pwm_chip *chip)
93{
94 return container_of(chip, struct atmel_pwm_chip, chip);
95}
96
97static inline u32 atmel_pwm_readl(struct atmel_pwm_chip *chip,
98 unsigned long offset)
99{
100 return readl_relaxed(chip->base + offset);
101}
102
103static inline void atmel_pwm_writel(struct atmel_pwm_chip *chip,
104 unsigned long offset, unsigned long val)
105{
106 writel_relaxed(val, chip->base + offset);
107}
108
109static inline u32 atmel_pwm_ch_readl(struct atmel_pwm_chip *chip,
110 unsigned int ch, unsigned long offset)
111{
112 unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE;
113
114 return atmel_pwm_readl(chip, base + offset);
115}
116
117static inline void atmel_pwm_ch_writel(struct atmel_pwm_chip *chip,
118 unsigned int ch, unsigned long offset,
119 unsigned long val)
120{
121 unsigned long base = PWM_CH_REG_OFFSET + ch * PWM_CH_REG_SIZE;
122
123 atmel_pwm_writel(chip, base + offset, val);
124}
125
126static int atmel_pwm_calculate_cprd_and_pres(struct pwm_chip *chip,
127 unsigned long clkrate,
128 const struct pwm_state *state,
129 unsigned long *cprd, u32 *pres)
130{
131 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
132 unsigned long long cycles = state->period;
133 int shift;
134
135 /* Calculate the period cycles and prescale value */
136 cycles *= clkrate;
137 do_div(cycles, NSEC_PER_SEC);
138
139 /*
140 * The register for the period length is cfg.period_bits bits wide.
141 * So for each bit the number of clock cycles is wider divide the input
142 * clock frequency by two using pres and shift cprd accordingly.
143 */
144 shift = fls(cycles) - atmel_pwm->data->cfg.period_bits;
145
146 if (shift > PWM_MAX_PRES) {
147 dev_err(chip->dev, "pres exceeds the maximum value\n");
148 return -EINVAL;
149 } else if (shift > 0) {
150 *pres = shift;
151 cycles >>= *pres;
152 } else {
153 *pres = 0;
154 }
155
156 *cprd = cycles;
157
158 return 0;
159}
160
161static void atmel_pwm_calculate_cdty(const struct pwm_state *state,
162 unsigned long clkrate, unsigned long cprd,
163 u32 pres, unsigned long *cdty)
164{
165 unsigned long long cycles = state->duty_cycle;
166
167 cycles *= clkrate;
168 do_div(cycles, NSEC_PER_SEC);
169 cycles >>= pres;
170 *cdty = cprd - cycles;
171}
172
173static void atmel_pwm_update_cdty(struct pwm_chip *chip, struct pwm_device *pwm,
174 unsigned long cdty)
175{
176 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
177 u32 val;
178
179 if (atmel_pwm->data->regs.duty_upd ==
180 atmel_pwm->data->regs.period_upd) {
181 val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
182 val &= ~PWM_CMR_UPD_CDTY;
183 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
184 }
185
186 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
187 atmel_pwm->data->regs.duty_upd, cdty);
188}
189
190static void atmel_pwm_set_cprd_cdty(struct pwm_chip *chip,
191 struct pwm_device *pwm,
192 unsigned long cprd, unsigned long cdty)
193{
194 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
195
196 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
197 atmel_pwm->data->regs.duty, cdty);
198 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm,
199 atmel_pwm->data->regs.period, cprd);
200}
201
202static void atmel_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm,
203 bool disable_clk)
204{
205 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
206 unsigned long timeout = jiffies + 2 * HZ;
207
208 /*
209 * Wait for at least a complete period to have passed before disabling a
210 * channel to be sure that CDTY has been updated
211 */
212 mutex_lock(&atmel_pwm->isr_lock);
213 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);
214
215 while (!(atmel_pwm->updated_pwms & (1 << pwm->hwpwm)) &&
216 time_before(jiffies, timeout)) {
217 usleep_range(10, 100);
218 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);
219 }
220
221 mutex_unlock(&atmel_pwm->isr_lock);
222 atmel_pwm_writel(atmel_pwm, PWM_DIS, 1 << pwm->hwpwm);
223
224 /*
225 * Wait for the PWM channel disable operation to be effective before
226 * stopping the clock.
227 */
228 timeout = jiffies + 2 * HZ;
229
230 while ((atmel_pwm_readl(atmel_pwm, PWM_SR) & (1 << pwm->hwpwm)) &&
231 time_before(jiffies, timeout))
232 usleep_range(10, 100);
233
234 if (disable_clk)
235 clk_disable(atmel_pwm->clk);
236}
237
238static int atmel_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
239 const struct pwm_state *state)
240{
241 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
242 struct pwm_state cstate;
243 unsigned long cprd, cdty;
244 u32 pres, val;
245 int ret;
246
247 pwm_get_state(pwm, &cstate);
248
249 if (state->enabled) {
250 unsigned long clkrate = clk_get_rate(atmel_pwm->clk);
251
252 if (cstate.enabled &&
253 cstate.polarity == state->polarity &&
254 cstate.period == state->period) {
255 u32 cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
256
257 cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
258 atmel_pwm->data->regs.period);
259 pres = cmr & PWM_CMR_CPRE_MSK;
260
261 atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty);
262 atmel_pwm_update_cdty(chip, pwm, cdty);
263 return 0;
264 }
265
266 ret = atmel_pwm_calculate_cprd_and_pres(chip, clkrate, state, &cprd,
267 &pres);
268 if (ret) {
269 dev_err(chip->dev,
270 "failed to calculate cprd and prescaler\n");
271 return ret;
272 }
273
274 atmel_pwm_calculate_cdty(state, clkrate, cprd, pres, &cdty);
275
276 if (cstate.enabled) {
277 atmel_pwm_disable(chip, pwm, false);
278 } else {
279 ret = clk_enable(atmel_pwm->clk);
280 if (ret) {
281 dev_err(chip->dev, "failed to enable clock\n");
282 return ret;
283 }
284 }
285
286 /* It is necessary to preserve CPOL, inside CMR */
287 val = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
288 val = (val & ~PWM_CMR_CPRE_MSK) | (pres & PWM_CMR_CPRE_MSK);
289 if (state->polarity == PWM_POLARITY_NORMAL)
290 val &= ~PWM_CMR_CPOL;
291 else
292 val |= PWM_CMR_CPOL;
293 atmel_pwm_ch_writel(atmel_pwm, pwm->hwpwm, PWM_CMR, val);
294 atmel_pwm_set_cprd_cdty(chip, pwm, cprd, cdty);
295 mutex_lock(&atmel_pwm->isr_lock);
296 atmel_pwm->updated_pwms |= atmel_pwm_readl(atmel_pwm, PWM_ISR);
297 atmel_pwm->updated_pwms &= ~(1 << pwm->hwpwm);
298 mutex_unlock(&atmel_pwm->isr_lock);
299 atmel_pwm_writel(atmel_pwm, PWM_ENA, 1 << pwm->hwpwm);
300 } else if (cstate.enabled) {
301 atmel_pwm_disable(chip, pwm, true);
302 }
303
304 return 0;
305}
306
307static void atmel_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
308 struct pwm_state *state)
309{
310 struct atmel_pwm_chip *atmel_pwm = to_atmel_pwm_chip(chip);
311 u32 sr, cmr;
312
313 sr = atmel_pwm_readl(atmel_pwm, PWM_SR);
314 cmr = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm, PWM_CMR);
315
316 if (sr & (1 << pwm->hwpwm)) {
317 unsigned long rate = clk_get_rate(atmel_pwm->clk);
318 u32 cdty, cprd, pres;
319 u64 tmp;
320
321 pres = cmr & PWM_CMR_CPRE_MSK;
322
323 cprd = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
324 atmel_pwm->data->regs.period);
325 tmp = (u64)cprd * NSEC_PER_SEC;
326 tmp <<= pres;
327 state->period = DIV64_U64_ROUND_UP(tmp, rate);
328
329 cdty = atmel_pwm_ch_readl(atmel_pwm, pwm->hwpwm,
330 atmel_pwm->data->regs.duty);
331 tmp = (u64)(cprd - cdty) * NSEC_PER_SEC;
332 tmp <<= pres;
333 state->duty_cycle = DIV64_U64_ROUND_UP(tmp, rate);
334
335 state->enabled = true;
336 } else {
337 state->enabled = false;
338 }
339
340 if (cmr & PWM_CMR_CPOL)
341 state->polarity = PWM_POLARITY_INVERSED;
342 else
343 state->polarity = PWM_POLARITY_NORMAL;
344}
345
346static const struct pwm_ops atmel_pwm_ops = {
347 .apply = atmel_pwm_apply,
348 .get_state = atmel_pwm_get_state,
349 .owner = THIS_MODULE,
350};
351
352static const struct atmel_pwm_data atmel_sam9rl_pwm_data = {
353 .regs = {
354 .period = PWMV1_CPRD,
355 .period_upd = PWMV1_CUPD,
356 .duty = PWMV1_CDTY,
357 .duty_upd = PWMV1_CUPD,
358 },
359 .cfg = {
360 /* 16 bits to keep period and duty. */
361 .period_bits = 16,
362 },
363};
364
365static const struct atmel_pwm_data atmel_sama5_pwm_data = {
366 .regs = {
367 .period = PWMV2_CPRD,
368 .period_upd = PWMV2_CPRDUPD,
369 .duty = PWMV2_CDTY,
370 .duty_upd = PWMV2_CDTYUPD,
371 },
372 .cfg = {
373 /* 16 bits to keep period and duty. */
374 .period_bits = 16,
375 },
376};
377
378static const struct atmel_pwm_data mchp_sam9x60_pwm_data = {
379 .regs = {
380 .period = PWMV1_CPRD,
381 .period_upd = PWMV1_CUPD,
382 .duty = PWMV1_CDTY,
383 .duty_upd = PWMV1_CUPD,
384 },
385 .cfg = {
386 /* 32 bits to keep period and duty. */
387 .period_bits = 32,
388 },
389};
390
391static const struct of_device_id atmel_pwm_dt_ids[] = {
392 {
393 .compatible = "atmel,at91sam9rl-pwm",
394 .data = &atmel_sam9rl_pwm_data,
395 }, {
396 .compatible = "atmel,sama5d3-pwm",
397 .data = &atmel_sama5_pwm_data,
398 }, {
399 .compatible = "atmel,sama5d2-pwm",
400 .data = &atmel_sama5_pwm_data,
401 }, {
402 .compatible = "microchip,sam9x60-pwm",
403 .data = &mchp_sam9x60_pwm_data,
404 }, {
405 /* sentinel */
406 },
407};
408MODULE_DEVICE_TABLE(of, atmel_pwm_dt_ids);
409
410static int atmel_pwm_probe(struct platform_device *pdev)
411{
412 struct atmel_pwm_chip *atmel_pwm;
413 int ret;
414
415 atmel_pwm = devm_kzalloc(&pdev->dev, sizeof(*atmel_pwm), GFP_KERNEL);
416 if (!atmel_pwm)
417 return -ENOMEM;
418
419 mutex_init(&atmel_pwm->isr_lock);
420 atmel_pwm->data = of_device_get_match_data(&pdev->dev);
421 atmel_pwm->updated_pwms = 0;
422
423 atmel_pwm->base = devm_platform_ioremap_resource(pdev, 0);
424 if (IS_ERR(atmel_pwm->base))
425 return PTR_ERR(atmel_pwm->base);
426
427 atmel_pwm->clk = devm_clk_get(&pdev->dev, NULL);
428 if (IS_ERR(atmel_pwm->clk))
429 return PTR_ERR(atmel_pwm->clk);
430
431 ret = clk_prepare(atmel_pwm->clk);
432 if (ret) {
433 dev_err(&pdev->dev, "failed to prepare PWM clock\n");
434 return ret;
435 }
436
437 atmel_pwm->chip.dev = &pdev->dev;
438 atmel_pwm->chip.ops = &atmel_pwm_ops;
439 atmel_pwm->chip.npwm = 4;
440
441 ret = pwmchip_add(&atmel_pwm->chip);
442 if (ret < 0) {
443 dev_err(&pdev->dev, "failed to add PWM chip %d\n", ret);
444 goto unprepare_clk;
445 }
446
447 platform_set_drvdata(pdev, atmel_pwm);
448
449 return ret;
450
451unprepare_clk:
452 clk_unprepare(atmel_pwm->clk);
453 return ret;
454}
455
456static int atmel_pwm_remove(struct platform_device *pdev)
457{
458 struct atmel_pwm_chip *atmel_pwm = platform_get_drvdata(pdev);
459
460 pwmchip_remove(&atmel_pwm->chip);
461
462 clk_unprepare(atmel_pwm->clk);
463 mutex_destroy(&atmel_pwm->isr_lock);
464
465 return 0;
466}
467
468static struct platform_driver atmel_pwm_driver = {
469 .driver = {
470 .name = "atmel-pwm",
471 .of_match_table = of_match_ptr(atmel_pwm_dt_ids),
472 },
473 .probe = atmel_pwm_probe,
474 .remove = atmel_pwm_remove,
475};
476module_platform_driver(atmel_pwm_driver);
477
478MODULE_ALIAS("platform:atmel-pwm");
479MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>");
480MODULE_DESCRIPTION("Atmel PWM driver");
481MODULE_LICENSE("GPL v2");