2 * PWM device driver for ST SoCs.
3 * Author: Ajit Pal Singh <ajitpal.singh@st.com>
5 * Copyright (C) 2013-2014 STMicroelectronics (R&D) Limited
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
13 #include <linux/clk.h>
14 #include <linux/math64.h>
15 #include <linux/mfd/syscon.h>
16 #include <linux/module.h>
18 #include <linux/platform_device.h>
19 #include <linux/pwm.h>
20 #include <linux/regmap.h>
21 #include <linux/slab.h>
22 #include <linux/time.h>
24 #define PWM_OUT_VAL(x) (0x00 + (4 * (x))) /* Device's Duty Cycle register */
26 #define STI_PWM_CTRL 0x50 /* Control/Config register */
27 #define STI_INT_EN 0x54 /* Interrupt Enable/Disable register */
28 #define PWM_PRESCALE_LOW_MASK 0x0f
29 #define PWM_PRESCALE_HIGH_MASK 0xf0
45 struct sti_pwm_compat_data {
46 const struct reg_field *reg_fields;
47 unsigned int num_devs;
48 unsigned int max_pwm_cnt;
49 unsigned int max_prescale;
55 struct regmap *regmap;
56 struct sti_pwm_compat_data *cdata;
57 struct regmap_field *prescale_low;
58 struct regmap_field *prescale_high;
59 struct regmap_field *pwm_out_en;
60 struct regmap_field *pwm_cpt_int_en;
62 struct pwm_device *cur;
63 unsigned long configured;
64 unsigned int en_count;
65 struct mutex sti_pwm_lock; /* To sync between enable/disable calls */
69 static const struct reg_field sti_pwm_regfields[MAX_REGFIELDS] = {
70 [PWMCLK_PRESCALE_LOW] = REG_FIELD(STI_PWM_CTRL, 0, 3),
71 [PWMCLK_PRESCALE_HIGH] = REG_FIELD(STI_PWM_CTRL, 11, 14),
72 [PWM_OUT_EN] = REG_FIELD(STI_PWM_CTRL, 9, 9),
73 [PWM_CPT_INT_EN] = REG_FIELD(STI_INT_EN, 1, 4),
76 static inline struct sti_pwm_chip *to_sti_pwmchip(struct pwm_chip *chip)
78 return container_of(chip, struct sti_pwm_chip, chip);
82 * Calculate the prescaler value corresponding to the period.
84 static int sti_pwm_get_prescale(struct sti_pwm_chip *pc, unsigned long period,
85 unsigned int *prescale)
87 struct sti_pwm_compat_data *cdata = pc->cdata;
88 unsigned long clk_rate;
92 clk_rate = clk_get_rate(pc->pwm_clk);
94 dev_err(pc->dev, "failed to get clock rate\n");
99 * prescale = ((period_ns * clk_rate) / (10^9 * (max_pwm_count + 1)) - 1
101 val = NSEC_PER_SEC / clk_rate;
102 val *= cdata->max_pwm_cnt + 1;
107 ps = period / val - 1;
108 if (ps > cdata->max_prescale)
117 * For STiH4xx PWM IP, the PWM period is fixed to 256 local clock cycles.
118 * The only way to change the period (apart from changing the PWM input clock)
119 * is to change the PWM clock prescaler.
120 * The prescaler is of 8 bits, so 256 prescaler values and hence
121 * 256 possible period values are supported (for a particular clock rate).
122 * The requested period will be applied only if it matches one of these
125 static int sti_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
126 int duty_ns, int period_ns)
128 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
129 struct sti_pwm_compat_data *cdata = pc->cdata;
130 struct pwm_device *cur = pc->cur;
131 struct device *dev = pc->dev;
132 unsigned int prescale = 0, pwmvalx;
135 bool period_same = false;
137 ncfg = hweight_long(pc->configured);
139 period_same = (period_ns == pwm_get_period(cur));
141 /* Allow configuration changes if one of the
142 * following conditions satisfy.
143 * 1. No devices have been configured.
144 * 2. Only one device has been configured and the new request
145 * is for the same device.
146 * 3. Only one device has been configured and the new request is
147 * for a new device and period of the new device is same as
148 * the current configured period.
149 * 4. More than one devices are configured and period of the new
150 * requestis the same as the current period.
153 ((ncfg == 1) && (pwm->hwpwm == cur->hwpwm)) ||
154 ((ncfg == 1) && (pwm->hwpwm != cur->hwpwm) && period_same) ||
155 ((ncfg > 1) && period_same)) {
156 /* Enable clock before writing to PWM registers. */
157 ret = clk_enable(pc->pwm_clk);
162 ret = sti_pwm_get_prescale(pc, period_ns, &prescale);
167 regmap_field_write(pc->prescale_low,
168 prescale & PWM_PRESCALE_LOW_MASK);
173 regmap_field_write(pc->prescale_high,
174 (prescale & PWM_PRESCALE_HIGH_MASK) >> 4);
180 * When PWMVal == 0, PWM pulse = 1 local clock cycle.
181 * When PWMVal == max_pwm_count,
182 * PWM pulse = (max_pwm_count + 1) local cycles,
183 * that is continuous pulse: signal never goes low.
185 pwmvalx = cdata->max_pwm_cnt * duty_ns / period_ns;
187 ret = regmap_write(pc->regmap,
188 PWM_OUT_VAL(pwm->hwpwm), pwmvalx);
192 ret = regmap_field_write(pc->pwm_cpt_int_en, 0);
194 set_bit(pwm->hwpwm, &pc->configured);
197 dev_dbg(dev, "prescale:%u, period:%i, duty:%i, pwmvalx:%u\n",
198 prescale, period_ns, duty_ns, pwmvalx);
204 clk_disable(pc->pwm_clk);
208 static int sti_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
210 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
211 struct device *dev = pc->dev;
215 * Since we have a common enable for all PWM devices,
216 * do not enable if already enabled.
218 mutex_lock(&pc->sti_pwm_lock);
220 ret = clk_enable(pc->pwm_clk);
224 ret = regmap_field_write(pc->pwm_out_en, 1);
226 dev_err(dev, "failed to enable PWM device:%d\n",
233 mutex_unlock(&pc->sti_pwm_lock);
237 static void sti_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
239 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
241 mutex_lock(&pc->sti_pwm_lock);
242 if (--pc->en_count) {
243 mutex_unlock(&pc->sti_pwm_lock);
246 regmap_field_write(pc->pwm_out_en, 0);
248 clk_disable(pc->pwm_clk);
249 mutex_unlock(&pc->sti_pwm_lock);
252 static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
254 struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
256 clear_bit(pwm->hwpwm, &pc->configured);
259 static const struct pwm_ops sti_pwm_ops = {
260 .config = sti_pwm_config,
261 .enable = sti_pwm_enable,
262 .disable = sti_pwm_disable,
263 .free = sti_pwm_free,
264 .owner = THIS_MODULE,
267 static int sti_pwm_probe_dt(struct sti_pwm_chip *pc)
269 struct device *dev = pc->dev;
270 const struct reg_field *reg_fields;
271 struct device_node *np = dev->of_node;
272 struct sti_pwm_compat_data *cdata = pc->cdata;
275 of_property_read_u32(np, "st,pwm-num-chan", &num_devs);
277 cdata->num_devs = num_devs;
279 reg_fields = cdata->reg_fields;
281 pc->prescale_low = devm_regmap_field_alloc(dev, pc->regmap,
282 reg_fields[PWMCLK_PRESCALE_LOW]);
283 if (IS_ERR(pc->prescale_low))
284 return PTR_ERR(pc->prescale_low);
286 pc->prescale_high = devm_regmap_field_alloc(dev, pc->regmap,
287 reg_fields[PWMCLK_PRESCALE_HIGH]);
288 if (IS_ERR(pc->prescale_high))
289 return PTR_ERR(pc->prescale_high);
292 pc->pwm_out_en = devm_regmap_field_alloc(dev, pc->regmap,
293 reg_fields[PWM_OUT_EN]);
294 if (IS_ERR(pc->pwm_out_en))
295 return PTR_ERR(pc->pwm_out_en);
297 pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap,
298 reg_fields[PWM_CPT_INT_EN]);
299 if (IS_ERR(pc->pwm_cpt_int_en))
300 return PTR_ERR(pc->pwm_cpt_int_en);
305 static const struct regmap_config sti_pwm_regmap_config = {
311 static int sti_pwm_probe(struct platform_device *pdev)
313 struct device *dev = &pdev->dev;
314 struct sti_pwm_compat_data *cdata;
315 struct sti_pwm_chip *pc;
316 struct resource *res;
319 pc = devm_kzalloc(dev, sizeof(*pc), GFP_KERNEL);
323 cdata = devm_kzalloc(dev, sizeof(*cdata), GFP_KERNEL);
327 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
329 pc->mmio = devm_ioremap_resource(dev, res);
330 if (IS_ERR(pc->mmio))
331 return PTR_ERR(pc->mmio);
333 pc->regmap = devm_regmap_init_mmio(dev, pc->mmio,
334 &sti_pwm_regmap_config);
335 if (IS_ERR(pc->regmap))
336 return PTR_ERR(pc->regmap);
339 * Setup PWM data with default values: some values could be replaced
340 * with specific ones provided from Device Tree.
342 cdata->reg_fields = &sti_pwm_regfields[0];
343 cdata->max_prescale = 0xff;
344 cdata->max_pwm_cnt = 255;
350 mutex_init(&pc->sti_pwm_lock);
352 ret = sti_pwm_probe_dt(pc);
356 pc->pwm_clk = of_clk_get_by_name(dev->of_node, "pwm");
357 if (IS_ERR(pc->pwm_clk)) {
358 dev_err(dev, "failed to get PWM clock\n");
359 return PTR_ERR(pc->pwm_clk);
362 ret = clk_prepare(pc->pwm_clk);
364 dev_err(dev, "failed to prepare clock\n");
369 pc->chip.ops = &sti_pwm_ops;
371 pc->chip.npwm = pc->cdata->num_devs;
372 pc->chip.can_sleep = true;
374 ret = pwmchip_add(&pc->chip);
376 clk_unprepare(pc->pwm_clk);
380 platform_set_drvdata(pdev, pc);
385 static int sti_pwm_remove(struct platform_device *pdev)
387 struct sti_pwm_chip *pc = platform_get_drvdata(pdev);
390 for (i = 0; i < pc->cdata->num_devs; i++)
391 pwm_disable(&pc->chip.pwms[i]);
393 clk_unprepare(pc->pwm_clk);
395 return pwmchip_remove(&pc->chip);
398 static const struct of_device_id sti_pwm_of_match[] = {
399 { .compatible = "st,sti-pwm", },
402 MODULE_DEVICE_TABLE(of, sti_pwm_of_match);
404 static struct platform_driver sti_pwm_driver = {
407 .of_match_table = sti_pwm_of_match,
409 .probe = sti_pwm_probe,
410 .remove = sti_pwm_remove,
412 module_platform_driver(sti_pwm_driver);
414 MODULE_AUTHOR("Ajit Pal Singh <ajitpal.singh@st.com>");
415 MODULE_DESCRIPTION("STMicroelectronics ST PWM driver");
416 MODULE_LICENSE("GPL");