1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (c) 2015 Neil Armstrong <narmstrong@baylibre.com>
4 * Copyright (c) 2014 Joachim Eastwood <manabian@gmail.com>
5 * Copyright (c) 2012 NeilBrown <neilb@suse.de>
6 * Heavily based on earlier code which is:
7 * Copyright (c) 2010 Grant Erickson <marathon96@gmail.com>
8 *
9 * Also based on pwm-samsung.c
10 *
11 * Description:
12 * This file is the core OMAP support for the generic, Linux
13 * PWM driver / controller, using the OMAP's dual-mode timers.
14 */
15
16 #include <linux/clk.h>
17 #include <linux/err.h>
18 #include <linux/kernel.h>
19 #include <linux/module.h>
20 #include <linux/mutex.h>
21 #include <linux/of.h>
22 #include <linux/of_platform.h>
23 #include <linux/platform_data/dmtimer-omap.h>
24 #include <linux/platform_data/pwm_omap_dmtimer.h>
25 #include <linux/platform_device.h>
26 #include <linux/pm_runtime.h>
27 #include <linux/pwm.h>
28 #include <linux/slab.h>
29 #include <linux/time.h>
30
31 #define DM_TIMER_LOAD_MIN 0xfffffffe
32 #define DM_TIMER_MAX 0xffffffff
33
34 struct pwm_omap_dmtimer_chip {
35 struct pwm_chip chip;
36 struct mutex mutex;
37 pwm_omap_dmtimer *dm_timer;
38 const struct omap_dm_timer_ops *pdata;
39 struct platform_device *dm_timer_pdev;
40 };
41
42 static inline struct pwm_omap_dmtimer_chip *
to_pwm_omap_dmtimer_chip(struct pwm_chip * chip)43 to_pwm_omap_dmtimer_chip(struct pwm_chip *chip)
44 {
45 return container_of(chip, struct pwm_omap_dmtimer_chip, chip);
46 }
47
pwm_omap_dmtimer_get_clock_cycles(unsigned long clk_rate,int ns)48 static u32 pwm_omap_dmtimer_get_clock_cycles(unsigned long clk_rate, int ns)
49 {
50 return DIV_ROUND_CLOSEST_ULL((u64)clk_rate * ns, NSEC_PER_SEC);
51 }
52
pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip * omap)53 static void pwm_omap_dmtimer_start(struct pwm_omap_dmtimer_chip *omap)
54 {
55 /*
56 * According to OMAP 4 TRM section 22.2.4.10 the counter should be
57 * started at 0xFFFFFFFE when overflow and match is used to ensure
58 * that the PWM line is toggled on the first event.
59 *
60 * Note that omap_dm_timer_enable/disable is for register access and
61 * not the timer counter itself.
62 */
63 omap->pdata->enable(omap->dm_timer);
64 omap->pdata->write_counter(omap->dm_timer, DM_TIMER_LOAD_MIN);
65 omap->pdata->disable(omap->dm_timer);
66
67 omap->pdata->start(omap->dm_timer);
68 }
69
pwm_omap_dmtimer_enable(struct pwm_chip * chip,struct pwm_device * pwm)70 static int pwm_omap_dmtimer_enable(struct pwm_chip *chip,
71 struct pwm_device *pwm)
72 {
73 struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
74
75 mutex_lock(&omap->mutex);
76 pwm_omap_dmtimer_start(omap);
77 mutex_unlock(&omap->mutex);
78
79 return 0;
80 }
81
pwm_omap_dmtimer_disable(struct pwm_chip * chip,struct pwm_device * pwm)82 static void pwm_omap_dmtimer_disable(struct pwm_chip *chip,
83 struct pwm_device *pwm)
84 {
85 struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
86
87 mutex_lock(&omap->mutex);
88 omap->pdata->stop(omap->dm_timer);
89 mutex_unlock(&omap->mutex);
90 }
91
pwm_omap_dmtimer_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)92 static int pwm_omap_dmtimer_config(struct pwm_chip *chip,
93 struct pwm_device *pwm,
94 int duty_ns, int period_ns)
95 {
96 struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
97 u32 period_cycles, duty_cycles;
98 u32 load_value, match_value;
99 struct clk *fclk;
100 unsigned long clk_rate;
101 bool timer_active;
102
103 dev_dbg(chip->dev, "requested duty cycle: %d ns, period: %d ns\n",
104 duty_ns, period_ns);
105
106 mutex_lock(&omap->mutex);
107 if (duty_ns == pwm_get_duty_cycle(pwm) &&
108 period_ns == pwm_get_period(pwm)) {
109 /* No change - don't cause any transients. */
110 mutex_unlock(&omap->mutex);
111 return 0;
112 }
113
114 fclk = omap->pdata->get_fclk(omap->dm_timer);
115 if (!fclk) {
116 dev_err(chip->dev, "invalid pmtimer fclk\n");
117 goto err_einval;
118 }
119
120 clk_rate = clk_get_rate(fclk);
121 if (!clk_rate) {
122 dev_err(chip->dev, "invalid pmtimer fclk rate\n");
123 goto err_einval;
124 }
125
126 dev_dbg(chip->dev, "clk rate: %luHz\n", clk_rate);
127
128 /*
129 * Calculate the appropriate load and match values based on the
130 * specified period and duty cycle. The load value determines the
131 * period time and the match value determines the duty time.
132 *
133 * The period lasts for (DM_TIMER_MAX-load_value+1) clock cycles.
134 * Similarly, the active time lasts (match_value-load_value+1) cycles.
135 * The non-active time is the remainder: (DM_TIMER_MAX-match_value)
136 * clock cycles.
137 *
138 * NOTE: It is required that: load_value <= match_value < DM_TIMER_MAX
139 *
140 * References:
141 * OMAP4430/60/70 TRM sections 22.2.4.10 and 22.2.4.11
142 * AM335x Sitara TRM sections 20.1.3.5 and 20.1.3.6
143 */
144 period_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, period_ns);
145 duty_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, duty_ns);
146
147 if (period_cycles < 2) {
148 dev_info(chip->dev,
149 "period %d ns too short for clock rate %lu Hz\n",
150 period_ns, clk_rate);
151 goto err_einval;
152 }
153
154 if (duty_cycles < 1) {
155 dev_dbg(chip->dev,
156 "duty cycle %d ns is too short for clock rate %lu Hz\n",
157 duty_ns, clk_rate);
158 dev_dbg(chip->dev, "using minimum of 1 clock cycle\n");
159 duty_cycles = 1;
160 } else if (duty_cycles >= period_cycles) {
161 dev_dbg(chip->dev,
162 "duty cycle %d ns is too long for period %d ns at clock rate %lu Hz\n",
163 duty_ns, period_ns, clk_rate);
164 dev_dbg(chip->dev, "using maximum of 1 clock cycle less than period\n");
165 duty_cycles = period_cycles - 1;
166 }
167
168 dev_dbg(chip->dev, "effective duty cycle: %lld ns, period: %lld ns\n",
169 DIV_ROUND_CLOSEST_ULL((u64)NSEC_PER_SEC * duty_cycles,
170 clk_rate),
171 DIV_ROUND_CLOSEST_ULL((u64)NSEC_PER_SEC * period_cycles,
172 clk_rate));
173
174 load_value = (DM_TIMER_MAX - period_cycles) + 1;
175 match_value = load_value + duty_cycles - 1;
176
177 /*
178 * We MUST stop the associated dual-mode timer before attempting to
179 * write its registers, but calls to omap_dm_timer_start/stop must
180 * be balanced so check if timer is active before calling timer_stop.
181 */
182 timer_active = pm_runtime_active(&omap->dm_timer_pdev->dev);
183 if (timer_active)
184 omap->pdata->stop(omap->dm_timer);
185
186 omap->pdata->set_load(omap->dm_timer, true, load_value);
187 omap->pdata->set_match(omap->dm_timer, true, match_value);
188
189 dev_dbg(chip->dev, "load value: %#08x (%d), match value: %#08x (%d)\n",
190 load_value, load_value, match_value, match_value);
191
192 omap->pdata->set_pwm(omap->dm_timer,
193 pwm_get_polarity(pwm) == PWM_POLARITY_INVERSED,
194 true,
195 PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);
196
197 /* If config was called while timer was running it must be reenabled. */
198 if (timer_active)
199 pwm_omap_dmtimer_start(omap);
200
201 mutex_unlock(&omap->mutex);
202
203 return 0;
204
205 err_einval:
206 mutex_unlock(&omap->mutex);
207
208 return -EINVAL;
209 }
210
pwm_omap_dmtimer_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)211 static int pwm_omap_dmtimer_set_polarity(struct pwm_chip *chip,
212 struct pwm_device *pwm,
213 enum pwm_polarity polarity)
214 {
215 struct pwm_omap_dmtimer_chip *omap = to_pwm_omap_dmtimer_chip(chip);
216
217 /*
218 * PWM core will not call set_polarity while PWM is enabled so it's
219 * safe to reconfigure the timer here without stopping it first.
220 */
221 mutex_lock(&omap->mutex);
222 omap->pdata->set_pwm(omap->dm_timer,
223 polarity == PWM_POLARITY_INVERSED,
224 true,
225 PWM_OMAP_DMTIMER_TRIGGER_OVERFLOW_AND_COMPARE);
226 mutex_unlock(&omap->mutex);
227
228 return 0;
229 }
230
231 static const struct pwm_ops pwm_omap_dmtimer_ops = {
232 .enable = pwm_omap_dmtimer_enable,
233 .disable = pwm_omap_dmtimer_disable,
234 .config = pwm_omap_dmtimer_config,
235 .set_polarity = pwm_omap_dmtimer_set_polarity,
236 .owner = THIS_MODULE,
237 };
238
pwm_omap_dmtimer_probe(struct platform_device * pdev)239 static int pwm_omap_dmtimer_probe(struct platform_device *pdev)
240 {
241 struct device_node *np = pdev->dev.of_node;
242 struct device_node *timer;
243 struct platform_device *timer_pdev;
244 struct pwm_omap_dmtimer_chip *omap;
245 struct dmtimer_platform_data *timer_pdata;
246 const struct omap_dm_timer_ops *pdata;
247 pwm_omap_dmtimer *dm_timer;
248 u32 v;
249 int ret = 0;
250
251 timer = of_parse_phandle(np, "ti,timers", 0);
252 if (!timer)
253 return -ENODEV;
254
255 timer_pdev = of_find_device_by_node(timer);
256 if (!timer_pdev) {
257 dev_err(&pdev->dev, "Unable to find Timer pdev\n");
258 ret = -ENODEV;
259 goto put;
260 }
261
262 timer_pdata = dev_get_platdata(&timer_pdev->dev);
263 if (!timer_pdata) {
264 dev_dbg(&pdev->dev,
265 "dmtimer pdata structure NULL, deferring probe\n");
266 ret = -EPROBE_DEFER;
267 goto put;
268 }
269
270 pdata = timer_pdata->timer_ops;
271
272 if (!pdata || !pdata->request_by_node ||
273 !pdata->free ||
274 !pdata->enable ||
275 !pdata->disable ||
276 !pdata->get_fclk ||
277 !pdata->start ||
278 !pdata->stop ||
279 !pdata->set_load ||
280 !pdata->set_match ||
281 !pdata->set_pwm ||
282 !pdata->set_prescaler ||
283 !pdata->write_counter) {
284 dev_err(&pdev->dev, "Incomplete dmtimer pdata structure\n");
285 ret = -EINVAL;
286 goto put;
287 }
288
289 if (!of_get_property(timer, "ti,timer-pwm", NULL)) {
290 dev_err(&pdev->dev, "Missing ti,timer-pwm capability\n");
291 ret = -ENODEV;
292 goto put;
293 }
294
295 dm_timer = pdata->request_by_node(timer);
296 if (!dm_timer) {
297 ret = -EPROBE_DEFER;
298 goto put;
299 }
300
301 put:
302 of_node_put(timer);
303 if (ret < 0)
304 return ret;
305
306 omap = devm_kzalloc(&pdev->dev, sizeof(*omap), GFP_KERNEL);
307 if (!omap) {
308 pdata->free(dm_timer);
309 return -ENOMEM;
310 }
311
312 omap->pdata = pdata;
313 omap->dm_timer = dm_timer;
314 omap->dm_timer_pdev = timer_pdev;
315
316 /*
317 * Ensure that the timer is stopped before we allow PWM core to call
318 * pwm_enable.
319 */
320 if (pm_runtime_active(&omap->dm_timer_pdev->dev))
321 omap->pdata->stop(omap->dm_timer);
322
323 if (!of_property_read_u32(pdev->dev.of_node, "ti,prescaler", &v))
324 omap->pdata->set_prescaler(omap->dm_timer, v);
325
326 /* setup dmtimer clock source */
327 if (!of_property_read_u32(pdev->dev.of_node, "ti,clock-source", &v))
328 omap->pdata->set_source(omap->dm_timer, v);
329
330 omap->chip.dev = &pdev->dev;
331 omap->chip.ops = &pwm_omap_dmtimer_ops;
332 omap->chip.base = -1;
333 omap->chip.npwm = 1;
334 omap->chip.of_xlate = of_pwm_xlate_with_flags;
335 omap->chip.of_pwm_n_cells = 3;
336
337 mutex_init(&omap->mutex);
338
339 ret = pwmchip_add(&omap->chip);
340 if (ret < 0) {
341 dev_err(&pdev->dev, "failed to register PWM\n");
342 omap->pdata->free(omap->dm_timer);
343 return ret;
344 }
345
346 platform_set_drvdata(pdev, omap);
347
348 return 0;
349 }
350
pwm_omap_dmtimer_remove(struct platform_device * pdev)351 static int pwm_omap_dmtimer_remove(struct platform_device *pdev)
352 {
353 struct pwm_omap_dmtimer_chip *omap = platform_get_drvdata(pdev);
354
355 if (pm_runtime_active(&omap->dm_timer_pdev->dev))
356 omap->pdata->stop(omap->dm_timer);
357
358 omap->pdata->free(omap->dm_timer);
359
360 mutex_destroy(&omap->mutex);
361
362 return pwmchip_remove(&omap->chip);
363 }
364
365 static const struct of_device_id pwm_omap_dmtimer_of_match[] = {
366 {.compatible = "ti,omap-dmtimer-pwm"},
367 {}
368 };
369 MODULE_DEVICE_TABLE(of, pwm_omap_dmtimer_of_match);
370
371 static struct platform_driver pwm_omap_dmtimer_driver = {
372 .driver = {
373 .name = "omap-dmtimer-pwm",
374 .of_match_table = of_match_ptr(pwm_omap_dmtimer_of_match),
375 },
376 .probe = pwm_omap_dmtimer_probe,
377 .remove = pwm_omap_dmtimer_remove,
378 };
379 module_platform_driver(pwm_omap_dmtimer_driver);
380
381 MODULE_AUTHOR("Grant Erickson <marathon96@gmail.com>");
382 MODULE_AUTHOR("NeilBrown <neilb@suse.de>");
383 MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
384 MODULE_LICENSE("GPL v2");
385 MODULE_DESCRIPTION("OMAP PWM Driver using Dual-mode Timers");
386