1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * R-Mobile TPU PWM driver
4 *
5 * Copyright (C) 2012 Renesas Solutions Corp.
6 */
7
8 #include <linux/clk.h>
9 #include <linux/err.h>
10 #include <linux/io.h>
11 #include <linux/init.h>
12 #include <linux/ioport.h>
13 #include <linux/module.h>
14 #include <linux/mutex.h>
15 #include <linux/of.h>
16 #include <linux/platform_device.h>
17 #include <linux/pm_runtime.h>
18 #include <linux/pwm.h>
19 #include <linux/slab.h>
20 #include <linux/spinlock.h>
21
22 #define TPU_CHANNEL_MAX 4
23
24 #define TPU_TSTR 0x00 /* Timer start register (shared) */
25
26 #define TPU_TCRn 0x00 /* Timer control register */
27 #define TPU_TCR_CCLR_NONE (0 << 5)
28 #define TPU_TCR_CCLR_TGRA (1 << 5)
29 #define TPU_TCR_CCLR_TGRB (2 << 5)
30 #define TPU_TCR_CCLR_TGRC (5 << 5)
31 #define TPU_TCR_CCLR_TGRD (6 << 5)
32 #define TPU_TCR_CKEG_RISING (0 << 3)
33 #define TPU_TCR_CKEG_FALLING (1 << 3)
34 #define TPU_TCR_CKEG_BOTH (2 << 3)
35 #define TPU_TMDRn 0x04 /* Timer mode register */
36 #define TPU_TMDR_BFWT (1 << 6)
37 #define TPU_TMDR_BFB (1 << 5)
38 #define TPU_TMDR_BFA (1 << 4)
39 #define TPU_TMDR_MD_NORMAL (0 << 0)
40 #define TPU_TMDR_MD_PWM (2 << 0)
41 #define TPU_TIORn 0x08 /* Timer I/O control register */
42 #define TPU_TIOR_IOA_0 (0 << 0)
43 #define TPU_TIOR_IOA_0_CLR (1 << 0)
44 #define TPU_TIOR_IOA_0_SET (2 << 0)
45 #define TPU_TIOR_IOA_0_TOGGLE (3 << 0)
46 #define TPU_TIOR_IOA_1 (4 << 0)
47 #define TPU_TIOR_IOA_1_CLR (5 << 0)
48 #define TPU_TIOR_IOA_1_SET (6 << 0)
49 #define TPU_TIOR_IOA_1_TOGGLE (7 << 0)
50 #define TPU_TIERn 0x0c /* Timer interrupt enable register */
51 #define TPU_TSRn 0x10 /* Timer status register */
52 #define TPU_TCNTn 0x14 /* Timer counter */
53 #define TPU_TGRAn 0x18 /* Timer general register A */
54 #define TPU_TGRBn 0x1c /* Timer general register B */
55 #define TPU_TGRCn 0x20 /* Timer general register C */
56 #define TPU_TGRDn 0x24 /* Timer general register D */
57
58 #define TPU_CHANNEL_OFFSET 0x10
59 #define TPU_CHANNEL_SIZE 0x40
60
61 enum tpu_pin_state {
62 TPU_PIN_INACTIVE, /* Pin is driven inactive */
63 TPU_PIN_PWM, /* Pin is driven by PWM */
64 TPU_PIN_ACTIVE, /* Pin is driven active */
65 };
66
67 struct tpu_device;
68
69 struct tpu_pwm_device {
70 bool timer_on; /* Whether the timer is running */
71
72 struct tpu_device *tpu;
73 unsigned int channel; /* Channel number in the TPU */
74
75 enum pwm_polarity polarity;
76 unsigned int prescaler;
77 u16 period;
78 u16 duty;
79 };
80
81 struct tpu_device {
82 struct platform_device *pdev;
83 struct pwm_chip chip;
84 spinlock_t lock;
85
86 void __iomem *base;
87 struct clk *clk;
88 };
89
90 #define to_tpu_device(c) container_of(c, struct tpu_device, chip)
91
tpu_pwm_write(struct tpu_pwm_device * tpd,int reg_nr,u16 value)92 static void tpu_pwm_write(struct tpu_pwm_device *tpd, int reg_nr, u16 value)
93 {
94 void __iomem *base = tpd->tpu->base + TPU_CHANNEL_OFFSET
95 + tpd->channel * TPU_CHANNEL_SIZE;
96
97 iowrite16(value, base + reg_nr);
98 }
99
tpu_pwm_set_pin(struct tpu_pwm_device * tpd,enum tpu_pin_state state)100 static void tpu_pwm_set_pin(struct tpu_pwm_device *tpd,
101 enum tpu_pin_state state)
102 {
103 static const char * const states[] = { "inactive", "PWM", "active" };
104
105 dev_dbg(&tpd->tpu->pdev->dev, "%u: configuring pin as %s\n",
106 tpd->channel, states[state]);
107
108 switch (state) {
109 case TPU_PIN_INACTIVE:
110 tpu_pwm_write(tpd, TPU_TIORn,
111 tpd->polarity == PWM_POLARITY_INVERSED ?
112 TPU_TIOR_IOA_1 : TPU_TIOR_IOA_0);
113 break;
114 case TPU_PIN_PWM:
115 tpu_pwm_write(tpd, TPU_TIORn,
116 tpd->polarity == PWM_POLARITY_INVERSED ?
117 TPU_TIOR_IOA_0_SET : TPU_TIOR_IOA_1_CLR);
118 break;
119 case TPU_PIN_ACTIVE:
120 tpu_pwm_write(tpd, TPU_TIORn,
121 tpd->polarity == PWM_POLARITY_INVERSED ?
122 TPU_TIOR_IOA_0 : TPU_TIOR_IOA_1);
123 break;
124 }
125 }
126
tpu_pwm_start_stop(struct tpu_pwm_device * tpd,int start)127 static void tpu_pwm_start_stop(struct tpu_pwm_device *tpd, int start)
128 {
129 unsigned long flags;
130 u16 value;
131
132 spin_lock_irqsave(&tpd->tpu->lock, flags);
133 value = ioread16(tpd->tpu->base + TPU_TSTR);
134
135 if (start)
136 value |= 1 << tpd->channel;
137 else
138 value &= ~(1 << tpd->channel);
139
140 iowrite16(value, tpd->tpu->base + TPU_TSTR);
141 spin_unlock_irqrestore(&tpd->tpu->lock, flags);
142 }
143
tpu_pwm_timer_start(struct tpu_pwm_device * tpd)144 static int tpu_pwm_timer_start(struct tpu_pwm_device *tpd)
145 {
146 int ret;
147
148 if (!tpd->timer_on) {
149 /* Wake up device and enable clock. */
150 pm_runtime_get_sync(&tpd->tpu->pdev->dev);
151 ret = clk_prepare_enable(tpd->tpu->clk);
152 if (ret) {
153 dev_err(&tpd->tpu->pdev->dev, "cannot enable clock\n");
154 return ret;
155 }
156 tpd->timer_on = true;
157 }
158
159 /*
160 * Make sure the channel is stopped, as we need to reconfigure it
161 * completely. First drive the pin to the inactive state to avoid
162 * glitches.
163 */
164 tpu_pwm_set_pin(tpd, TPU_PIN_INACTIVE);
165 tpu_pwm_start_stop(tpd, false);
166
167 /*
168 * - Clear TCNT on TGRB match
169 * - Count on rising edge
170 * - Set prescaler
171 * - Output 0 until TGRA, output 1 until TGRB (active low polarity)
172 * - Output 1 until TGRA, output 0 until TGRB (active high polarity
173 * - PWM mode
174 */
175 tpu_pwm_write(tpd, TPU_TCRn, TPU_TCR_CCLR_TGRB | TPU_TCR_CKEG_RISING |
176 tpd->prescaler);
177 tpu_pwm_write(tpd, TPU_TMDRn, TPU_TMDR_MD_PWM);
178 tpu_pwm_set_pin(tpd, TPU_PIN_PWM);
179 tpu_pwm_write(tpd, TPU_TGRAn, tpd->duty);
180 tpu_pwm_write(tpd, TPU_TGRBn, tpd->period);
181
182 dev_dbg(&tpd->tpu->pdev->dev, "%u: TGRA 0x%04x TGRB 0x%04x\n",
183 tpd->channel, tpd->duty, tpd->period);
184
185 /* Start the channel. */
186 tpu_pwm_start_stop(tpd, true);
187
188 return 0;
189 }
190
tpu_pwm_timer_stop(struct tpu_pwm_device * tpd)191 static void tpu_pwm_timer_stop(struct tpu_pwm_device *tpd)
192 {
193 if (!tpd->timer_on)
194 return;
195
196 /* Disable channel. */
197 tpu_pwm_start_stop(tpd, false);
198
199 /* Stop clock and mark device as idle. */
200 clk_disable_unprepare(tpd->tpu->clk);
201 pm_runtime_put(&tpd->tpu->pdev->dev);
202
203 tpd->timer_on = false;
204 }
205
206 /* -----------------------------------------------------------------------------
207 * PWM API
208 */
209
tpu_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)210 static int tpu_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
211 {
212 struct tpu_device *tpu = to_tpu_device(chip);
213 struct tpu_pwm_device *tpd;
214
215 if (pwm->hwpwm >= TPU_CHANNEL_MAX)
216 return -EINVAL;
217
218 tpd = kzalloc(sizeof(*tpd), GFP_KERNEL);
219 if (tpd == NULL)
220 return -ENOMEM;
221
222 tpd->tpu = tpu;
223 tpd->channel = pwm->hwpwm;
224 tpd->polarity = PWM_POLARITY_NORMAL;
225 tpd->prescaler = 0;
226 tpd->period = 0;
227 tpd->duty = 0;
228
229 tpd->timer_on = false;
230
231 pwm_set_chip_data(pwm, tpd);
232
233 return 0;
234 }
235
tpu_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)236 static void tpu_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
237 {
238 struct tpu_pwm_device *tpd = pwm_get_chip_data(pwm);
239
240 tpu_pwm_timer_stop(tpd);
241 kfree(tpd);
242 }
243
tpu_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,u64 duty_ns,u64 period_ns,bool enabled)244 static int tpu_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
245 u64 duty_ns, u64 period_ns, bool enabled)
246 {
247 struct tpu_pwm_device *tpd = pwm_get_chip_data(pwm);
248 struct tpu_device *tpu = to_tpu_device(chip);
249 unsigned int prescaler;
250 bool duty_only = false;
251 u32 clk_rate;
252 u64 period;
253 u32 duty;
254 int ret;
255
256 clk_rate = clk_get_rate(tpu->clk);
257 if (unlikely(clk_rate > NSEC_PER_SEC)) {
258 /*
259 * This won't happen in the nearer future, so this is only a
260 * safeguard to prevent the following calculation from
261 * overflowing. With this clk_rate * period_ns / NSEC_PER_SEC is
262 * not greater than period_ns and so fits into an u64.
263 */
264 return -EINVAL;
265 }
266
267 period = mul_u64_u64_div_u64(clk_rate, period_ns, NSEC_PER_SEC);
268
269 /*
270 * Find the minimal prescaler in [0..3] such that
271 *
272 * period >> (2 * prescaler) < 0x10000
273 *
274 * This could be calculated using something like:
275 *
276 * prescaler = max(ilog2(period) / 2, 7) - 7;
277 *
278 * but given there are only four allowed results and that ilog2 isn't
279 * cheap on all platforms using a switch statement is more effective.
280 */
281 switch (period) {
282 case 1 ... 0xffff:
283 prescaler = 0;
284 break;
285
286 case 0x10000 ... 0x3ffff:
287 prescaler = 1;
288 break;
289
290 case 0x40000 ... 0xfffff:
291 prescaler = 2;
292 break;
293
294 case 0x100000 ... 0x3fffff:
295 prescaler = 3;
296 break;
297
298 default:
299 return -EINVAL;
300 }
301
302 period >>= 2 * prescaler;
303
304 if (duty_ns)
305 duty = mul_u64_u64_div_u64(clk_rate, duty_ns,
306 (u64)NSEC_PER_SEC << (2 * prescaler));
307 else
308 duty = 0;
309
310 dev_dbg(&tpu->pdev->dev,
311 "rate %u, prescaler %u, period %u, duty %u\n",
312 clk_rate, 1 << (2 * prescaler), (u32)period, duty);
313
314 if (tpd->prescaler == prescaler && tpd->period == period)
315 duty_only = true;
316
317 tpd->prescaler = prescaler;
318 tpd->period = period;
319 tpd->duty = duty;
320
321 /* If the channel is disabled we're done. */
322 if (!enabled)
323 return 0;
324
325 if (duty_only && tpd->timer_on) {
326 /*
327 * If only the duty cycle changed and the timer is already
328 * running, there's no need to reconfigure it completely, Just
329 * modify the duty cycle.
330 */
331 tpu_pwm_write(tpd, TPU_TGRAn, tpd->duty);
332 dev_dbg(&tpu->pdev->dev, "%u: TGRA 0x%04x\n", tpd->channel,
333 tpd->duty);
334 } else {
335 /* Otherwise perform a full reconfiguration. */
336 ret = tpu_pwm_timer_start(tpd);
337 if (ret < 0)
338 return ret;
339 }
340
341 if (duty == 0 || duty == period) {
342 /*
343 * To avoid running the timer when not strictly required, handle
344 * 0% and 100% duty cycles as fixed levels and stop the timer.
345 */
346 tpu_pwm_set_pin(tpd, duty ? TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
347 tpu_pwm_timer_stop(tpd);
348 }
349
350 return 0;
351 }
352
tpu_pwm_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)353 static int tpu_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
354 enum pwm_polarity polarity)
355 {
356 struct tpu_pwm_device *tpd = pwm_get_chip_data(pwm);
357
358 tpd->polarity = polarity;
359
360 return 0;
361 }
362
tpu_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)363 static int tpu_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
364 {
365 struct tpu_pwm_device *tpd = pwm_get_chip_data(pwm);
366 int ret;
367
368 ret = tpu_pwm_timer_start(tpd);
369 if (ret < 0)
370 return ret;
371
372 /*
373 * To avoid running the timer when not strictly required, handle 0% and
374 * 100% duty cycles as fixed levels and stop the timer.
375 */
376 if (tpd->duty == 0 || tpd->duty == tpd->period) {
377 tpu_pwm_set_pin(tpd, tpd->duty ?
378 TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
379 tpu_pwm_timer_stop(tpd);
380 }
381
382 return 0;
383 }
384
tpu_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)385 static void tpu_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
386 {
387 struct tpu_pwm_device *tpd = pwm_get_chip_data(pwm);
388
389 /* The timer must be running to modify the pin output configuration. */
390 tpu_pwm_timer_start(tpd);
391 tpu_pwm_set_pin(tpd, TPU_PIN_INACTIVE);
392 tpu_pwm_timer_stop(tpd);
393 }
394
tpu_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)395 static int tpu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
396 const struct pwm_state *state)
397 {
398 int err;
399 bool enabled = pwm->state.enabled;
400
401 if (state->polarity != pwm->state.polarity) {
402 if (enabled) {
403 tpu_pwm_disable(chip, pwm);
404 enabled = false;
405 }
406
407 err = tpu_pwm_set_polarity(chip, pwm, state->polarity);
408 if (err)
409 return err;
410 }
411
412 if (!state->enabled) {
413 if (enabled)
414 tpu_pwm_disable(chip, pwm);
415
416 return 0;
417 }
418
419 err = tpu_pwm_config(pwm->chip, pwm,
420 state->duty_cycle, state->period, enabled);
421 if (err)
422 return err;
423
424 if (!enabled)
425 err = tpu_pwm_enable(chip, pwm);
426
427 return err;
428 }
429
430 static const struct pwm_ops tpu_pwm_ops = {
431 .request = tpu_pwm_request,
432 .free = tpu_pwm_free,
433 .apply = tpu_pwm_apply,
434 .owner = THIS_MODULE,
435 };
436
437 /* -----------------------------------------------------------------------------
438 * Probe and remove
439 */
440
tpu_probe(struct platform_device * pdev)441 static int tpu_probe(struct platform_device *pdev)
442 {
443 struct tpu_device *tpu;
444 int ret;
445
446 tpu = devm_kzalloc(&pdev->dev, sizeof(*tpu), GFP_KERNEL);
447 if (tpu == NULL)
448 return -ENOMEM;
449
450 spin_lock_init(&tpu->lock);
451 tpu->pdev = pdev;
452
453 /* Map memory, get clock and pin control. */
454 tpu->base = devm_platform_ioremap_resource(pdev, 0);
455 if (IS_ERR(tpu->base))
456 return PTR_ERR(tpu->base);
457
458 tpu->clk = devm_clk_get(&pdev->dev, NULL);
459 if (IS_ERR(tpu->clk))
460 return dev_err_probe(&pdev->dev, PTR_ERR(tpu->clk), "Failed to get clock\n");
461
462 /* Initialize and register the device. */
463 platform_set_drvdata(pdev, tpu);
464
465 tpu->chip.dev = &pdev->dev;
466 tpu->chip.ops = &tpu_pwm_ops;
467 tpu->chip.npwm = TPU_CHANNEL_MAX;
468
469 ret = devm_pm_runtime_enable(&pdev->dev);
470 if (ret < 0)
471 return dev_err_probe(&pdev->dev, ret, "Failed to enable runtime PM\n");
472
473 ret = devm_pwmchip_add(&pdev->dev, &tpu->chip);
474 if (ret < 0)
475 return dev_err_probe(&pdev->dev, ret, "Failed to register PWM chip\n");
476
477 return 0;
478 }
479
480 #ifdef CONFIG_OF
481 static const struct of_device_id tpu_of_table[] = {
482 { .compatible = "renesas,tpu-r8a73a4", },
483 { .compatible = "renesas,tpu-r8a7740", },
484 { .compatible = "renesas,tpu-r8a7790", },
485 { .compatible = "renesas,tpu", },
486 { },
487 };
488
489 MODULE_DEVICE_TABLE(of, tpu_of_table);
490 #endif
491
492 static struct platform_driver tpu_driver = {
493 .probe = tpu_probe,
494 .driver = {
495 .name = "renesas-tpu-pwm",
496 .of_match_table = of_match_ptr(tpu_of_table),
497 }
498 };
499
500 module_platform_driver(tpu_driver);
501
502 MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
503 MODULE_DESCRIPTION("Renesas TPU PWM Driver");
504 MODULE_LICENSE("GPL v2");
505 MODULE_ALIAS("platform:renesas-tpu-pwm");
506