2 * Driver for Allwinner sun4i Pulse Width Modulation Controller
4 * Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@free-electrons.com>
6 * Licensed under GPLv2.
9 #include <linux/bitops.h>
10 #include <linux/clk.h>
11 #include <linux/delay.h>
12 #include <linux/err.h>
14 #include <linux/jiffies.h>
15 #include <linux/module.h>
17 #include <linux/of_device.h>
18 #include <linux/platform_device.h>
19 #include <linux/pwm.h>
20 #include <linux/slab.h>
21 #include <linux/spinlock.h>
22 #include <linux/time.h>
24 #define PWM_CTRL_REG 0x0
26 #define PWM_CH_PRD_BASE 0x4
27 #define PWM_CH_PRD_OFFSET 0x4
28 #define PWM_CH_PRD(ch) (PWM_CH_PRD_BASE + PWM_CH_PRD_OFFSET * (ch))
30 #define PWMCH_OFFSET 15
31 #define PWM_PRESCAL_MASK GENMASK(3, 0)
32 #define PWM_PRESCAL_OFF 0
34 #define PWM_ACT_STATE BIT(5)
35 #define PWM_CLK_GATING BIT(6)
36 #define PWM_MODE BIT(7)
37 #define PWM_PULSE BIT(8)
38 #define PWM_BYPASS BIT(9)
40 #define PWM_RDY_BASE 28
41 #define PWM_RDY_OFFSET 1
42 #define PWM_RDY(ch) BIT(PWM_RDY_BASE + PWM_RDY_OFFSET * (ch))
44 #define PWM_PRD(prd) (((prd) - 1) << 16)
45 #define PWM_PRD_MASK GENMASK(15, 0)
47 #define PWM_DTY_MASK GENMASK(15, 0)
49 #define PWM_REG_PRD(reg) ((((reg) >> 16) & PWM_PRD_MASK) + 1)
50 #define PWM_REG_DTY(reg) ((reg) & PWM_DTY_MASK)
51 #define PWM_REG_PRESCAL(reg, chan) (((reg) >> ((chan) * PWMCH_OFFSET)) & PWM_PRESCAL_MASK)
53 #define BIT_CH(bit, chan) ((bit) << ((chan) * PWMCH_OFFSET))
55 static const u32 prescaler_table[] = {
71 0, /* Actually 1 but tested separately */
74 struct sun4i_pwm_data {
75 bool has_prescaler_bypass;
80 struct sun4i_pwm_chip {
85 const struct sun4i_pwm_data *data;
86 unsigned long next_period[2];
90 static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip)
92 return container_of(chip, struct sun4i_pwm_chip, chip);
95 static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip,
98 return readl(chip->base + offset);
101 static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
102 u32 val, unsigned long offset)
104 writel(val, chip->base + offset);
107 static void sun4i_pwm_get_state(struct pwm_chip *chip,
108 struct pwm_device *pwm,
109 struct pwm_state *state)
111 struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
114 unsigned int prescaler;
116 clk_rate = clk_get_rate(sun4i_pwm->clk);
118 val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
120 if ((val == PWM_PRESCAL_MASK) && sun4i_pwm->data->has_prescaler_bypass)
123 prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)];
128 if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm))
129 state->polarity = PWM_POLARITY_NORMAL;
131 state->polarity = PWM_POLARITY_INVERSED;
133 if (val & BIT_CH(PWM_CLK_GATING | PWM_EN, pwm->hwpwm))
134 state->enabled = true;
136 state->enabled = false;
138 val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm));
140 tmp = prescaler * NSEC_PER_SEC * PWM_REG_DTY(val);
141 state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
143 tmp = prescaler * NSEC_PER_SEC * PWM_REG_PRD(val);
144 state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
147 static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
148 struct pwm_state *state,
149 u32 *dty, u32 *prd, unsigned int *prsclr)
151 u64 clk_rate, div = 0;
152 unsigned int pval, prescaler = 0;
154 clk_rate = clk_get_rate(sun4i_pwm->clk);
156 if (sun4i_pwm->data->has_prescaler_bypass) {
157 /* First, test without any prescaler when available */
158 prescaler = PWM_PRESCAL_MASK;
161 * When not using any prescaler, the clock period in nanoseconds
162 * is not an integer so round it half up instead of
163 * truncating to get less surprising values.
165 div = clk_rate * state->period + NSEC_PER_SEC / 2;
166 do_div(div, NSEC_PER_SEC);
167 if (div - 1 > PWM_PRD_MASK)
171 if (prescaler == 0) {
172 /* Go up from the first divider */
173 for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) {
174 if (!prescaler_table[prescaler])
176 pval = prescaler_table[prescaler];
179 div = div * state->period;
180 do_div(div, NSEC_PER_SEC);
181 if (div - 1 <= PWM_PRD_MASK)
185 if (div - 1 > PWM_PRD_MASK)
190 div *= state->duty_cycle;
191 do_div(div, state->period);
195 div = (u64)pval * NSEC_PER_SEC * *prd;
196 state->period = DIV_ROUND_CLOSEST_ULL(div, clk_rate);
198 div = (u64)pval * NSEC_PER_SEC * *dty;
199 state->duty_cycle = DIV_ROUND_CLOSEST_ULL(div, clk_rate);
204 static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
205 struct pwm_state *state)
207 struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
208 struct pwm_state cstate;
211 unsigned int delay_us;
214 pwm_get_state(pwm, &cstate);
216 if (!cstate.enabled) {
217 ret = clk_prepare_enable(sun4i_pwm->clk);
219 dev_err(chip->dev, "failed to enable PWM clock\n");
224 spin_lock(&sun4i_pwm->ctrl_lock);
225 ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
227 if ((cstate.period != state->period) ||
228 (cstate.duty_cycle != state->duty_cycle)) {
229 u32 period, duty, val;
230 unsigned int prescaler;
232 ret = sun4i_pwm_calculate(sun4i_pwm, state,
233 &duty, &period, &prescaler);
235 dev_err(chip->dev, "period exceeds the maximum value\n");
236 spin_unlock(&sun4i_pwm->ctrl_lock);
238 clk_disable_unprepare(sun4i_pwm->clk);
242 if (PWM_REG_PRESCAL(ctrl, pwm->hwpwm) != prescaler) {
243 /* Prescaler changed, the clock has to be gated */
244 ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
245 sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);
247 ctrl &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm);
248 ctrl |= BIT_CH(prescaler, pwm->hwpwm);
251 val = (duty & PWM_DTY_MASK) | PWM_PRD(period);
252 sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm));
253 sun4i_pwm->next_period[pwm->hwpwm] = jiffies +
254 usecs_to_jiffies(cstate.period / 1000 + 1);
255 sun4i_pwm->needs_delay[pwm->hwpwm] = true;
258 if (state->polarity != PWM_POLARITY_NORMAL)
259 ctrl &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
261 ctrl |= BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
263 ctrl |= BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
264 if (state->enabled) {
265 ctrl |= BIT_CH(PWM_EN, pwm->hwpwm);
266 } else if (!sun4i_pwm->needs_delay[pwm->hwpwm]) {
267 ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm);
268 ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
271 sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);
273 spin_unlock(&sun4i_pwm->ctrl_lock);
278 if (!sun4i_pwm->needs_delay[pwm->hwpwm]) {
279 clk_disable_unprepare(sun4i_pwm->clk);
283 /* We need a full period to elapse before disabling the channel. */
285 if (sun4i_pwm->needs_delay[pwm->hwpwm] &&
286 time_before(now, sun4i_pwm->next_period[pwm->hwpwm])) {
287 delay_us = jiffies_to_usecs(sun4i_pwm->next_period[pwm->hwpwm] -
289 if ((delay_us / 500) > MAX_UDELAY_MS)
290 msleep(delay_us / 1000 + 1);
292 usleep_range(delay_us, delay_us * 2);
294 sun4i_pwm->needs_delay[pwm->hwpwm] = false;
296 spin_lock(&sun4i_pwm->ctrl_lock);
297 ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
298 ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
299 ctrl &= ~BIT_CH(PWM_EN, pwm->hwpwm);
300 sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);
301 spin_unlock(&sun4i_pwm->ctrl_lock);
303 clk_disable_unprepare(sun4i_pwm->clk);
308 static const struct pwm_ops sun4i_pwm_ops = {
309 .apply = sun4i_pwm_apply,
310 .get_state = sun4i_pwm_get_state,
311 .owner = THIS_MODULE,
314 static const struct sun4i_pwm_data sun4i_pwm_data_a10 = {
315 .has_prescaler_bypass = false,
320 static const struct sun4i_pwm_data sun4i_pwm_data_a10s = {
321 .has_prescaler_bypass = true,
326 static const struct sun4i_pwm_data sun4i_pwm_data_a13 = {
327 .has_prescaler_bypass = true,
332 static const struct sun4i_pwm_data sun4i_pwm_data_a20 = {
333 .has_prescaler_bypass = true,
338 static const struct sun4i_pwm_data sun4i_pwm_data_h3 = {
339 .has_prescaler_bypass = true,
344 static const struct of_device_id sun4i_pwm_dt_ids[] = {
346 .compatible = "allwinner,sun4i-a10-pwm",
347 .data = &sun4i_pwm_data_a10,
349 .compatible = "allwinner,sun5i-a10s-pwm",
350 .data = &sun4i_pwm_data_a10s,
352 .compatible = "allwinner,sun5i-a13-pwm",
353 .data = &sun4i_pwm_data_a13,
355 .compatible = "allwinner,sun7i-a20-pwm",
356 .data = &sun4i_pwm_data_a20,
358 .compatible = "allwinner,sun8i-h3-pwm",
359 .data = &sun4i_pwm_data_h3,
364 MODULE_DEVICE_TABLE(of, sun4i_pwm_dt_ids);
366 static int sun4i_pwm_probe(struct platform_device *pdev)
368 struct sun4i_pwm_chip *pwm;
369 struct resource *res;
371 const struct of_device_id *match;
373 match = of_match_device(sun4i_pwm_dt_ids, &pdev->dev);
375 pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
379 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
380 pwm->base = devm_ioremap_resource(&pdev->dev, res);
381 if (IS_ERR(pwm->base))
382 return PTR_ERR(pwm->base);
384 pwm->clk = devm_clk_get(&pdev->dev, NULL);
385 if (IS_ERR(pwm->clk))
386 return PTR_ERR(pwm->clk);
388 pwm->data = match->data;
389 pwm->chip.dev = &pdev->dev;
390 pwm->chip.ops = &sun4i_pwm_ops;
392 pwm->chip.npwm = pwm->data->npwm;
393 pwm->chip.of_xlate = of_pwm_xlate_with_flags;
394 pwm->chip.of_pwm_n_cells = 3;
396 spin_lock_init(&pwm->ctrl_lock);
398 ret = pwmchip_add(&pwm->chip);
400 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
404 platform_set_drvdata(pdev, pwm);
409 static int sun4i_pwm_remove(struct platform_device *pdev)
411 struct sun4i_pwm_chip *pwm = platform_get_drvdata(pdev);
413 return pwmchip_remove(&pwm->chip);
416 static struct platform_driver sun4i_pwm_driver = {
419 .of_match_table = sun4i_pwm_dt_ids,
421 .probe = sun4i_pwm_probe,
422 .remove = sun4i_pwm_remove,
424 module_platform_driver(sun4i_pwm_driver);
426 MODULE_ALIAS("platform:sun4i-pwm");
427 MODULE_AUTHOR("Alexandre Belloni <alexandre.belloni@free-electrons.com>");
428 MODULE_DESCRIPTION("Allwinner sun4i PWM driver");
429 MODULE_LICENSE("GPL v2");