[PATCH v3] pwm: mediatek: Convert to waveform API
Uwe Kleine-König
u.kleine-koenig at baylibre.com
Mon Oct 13 04:42:56 PDT 2025
Implement the new waveform callbacks which makes the usage of this
hardware more flexible and allows to use it via the pwm character
device.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig at baylibre.com>
---
Hello,
this patch was part of a series before, find v2 at
https://lore.kernel.org/linux-pwm/20250725154506.2610172-10-u.kleine-koenig@baylibre.com
. All patches apart from this one was applied back then.
The problem here was, that the driver didn't properly work with the
newly added GPIO support (see commit v6.18-rc1~169^2~19 = e7c9b66b1069
("pwm: Provide a gpio device for waveform drivers")).
This is fixed here. The changes in detail are:
- Rebase over
ed5902a24648 pwm: mediatek: Lock and cache clock rate
849b064c1697 pwm: mediatek: Fix various issues in the .apply() callback
- Improve clk handling (don't only fail once for invalid clock rates)
- report minimal period for a disabled PWM in .round_waveform_fromhw()
(this fixes the above mentioned problem)
Best regards
Uwe
drivers/pwm/pwm-mediatek.c | 335 ++++++++++++++++++++++---------------
1 file changed, 201 insertions(+), 134 deletions(-)
diff --git a/drivers/pwm/pwm-mediatek.c b/drivers/pwm/pwm-mediatek.c
index 4291072a13a7..f2c918c0d26a 100644
--- a/drivers/pwm/pwm-mediatek.c
+++ b/drivers/pwm/pwm-mediatek.c
@@ -135,50 +135,51 @@ static inline u32 pwm_mediatek_readl(struct pwm_mediatek_chip *chip,
num * chip->soc->chanreg_width + offset);
}
-static void pwm_mediatek_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
- u32 value;
-
- value = readl(pc->regs);
- value |= BIT(pwm->hwpwm);
- writel(value, pc->regs);
-}
-
-static void pwm_mediatek_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
- struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
- u32 value;
-
- value = readl(pc->regs);
- value &= ~BIT(pwm->hwpwm);
- writel(value, pc->regs);
-}
-
-static int pwm_mediatek_config(struct pwm_chip *chip, struct pwm_device *pwm,
- u64 duty_ns, u64 period_ns)
+struct pwm_mediatek_waveform {
+ u32 enable;
+ u32 con;
+ u32 width;
+ u32 thres;
+};
+
+static int pwm_mediatek_round_waveform_tohw(struct pwm_chip *chip, struct pwm_device *pwm,
+ const struct pwm_waveform *wf, void *_wfhw)
{
+ struct pwm_mediatek_waveform *wfhw = _wfhw;
struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
u32 clkdiv, enable;
- u32 reg_width = PWMDWIDTH, reg_thres = PWMTHRES;
u64 cnt_period, cnt_duty;
unsigned long clk_rate;
- int ret;
+ int ret = 0;
- ret = pwm_mediatek_clk_enable(pc, pwm->hwpwm);
- if (ret < 0)
- return ret;
+ if (wf->period_length_ns == 0) {
+ *wfhw = (typeof(*wfhw)){
+ .enable = 0,
+ };
+
+ return 0;
+ }
+
+ if (!pc->clk_pwms[pwm->hwpwm].rate) {
+ struct clk *clk = pc->clk_pwms[pwm->hwpwm].clk;
+
+ ret = clk_prepare_enable(clk);
+ if (ret)
+ return ret;
+
+ pc->clk_pwms[pwm->hwpwm].rate = clk_get_rate(clk);
+
+ clk_disable_unprepare(clk);
+ }
clk_rate = pc->clk_pwms[pwm->hwpwm].rate;
+ if (clk_rate == 0 || clk_rate > 1000000000)
+ return -EINVAL;
- /* Make sure we use the bus clock and not the 26MHz clock */
- if (pc->soc->pwm_ck_26m_sel_reg)
- writel(0, pc->regs + pc->soc->pwm_ck_26m_sel_reg);
-
- cnt_period = mul_u64_u64_div_u64(period_ns, clk_rate, NSEC_PER_SEC);
+ cnt_period = mul_u64_u64_div_u64(wf->period_length_ns, clk_rate, NSEC_PER_SEC);
if (cnt_period == 0) {
- ret = -ERANGE;
- goto out;
+ cnt_period = 1;
+ ret = 1;
}
if (cnt_period > FIELD_MAX(PWMDWIDTH_PERIOD) + 1) {
@@ -193,7 +194,7 @@ static int pwm_mediatek_config(struct pwm_chip *chip, struct pwm_device *pwm,
clkdiv = 0;
}
- cnt_duty = mul_u64_u64_div_u64(duty_ns, clk_rate, NSEC_PER_SEC) >> clkdiv;
+ cnt_duty = mul_u64_u64_div_u64(wf->duty_length_ns, clk_rate, NSEC_PER_SEC) >> clkdiv;
if (cnt_duty > cnt_period)
cnt_duty = cnt_period;
@@ -206,26 +207,173 @@ static int pwm_mediatek_config(struct pwm_chip *chip, struct pwm_device *pwm,
cnt_period -= 1;
- dev_dbg(&chip->dev, "pwm#%u: %lld/%lld @%lu -> CON: %x, PERIOD: %llx, DUTY: %llx\n",
- pwm->hwpwm, duty_ns, period_ns, clk_rate, clkdiv, cnt_period, cnt_duty);
+ dev_dbg(&chip->dev, "pwm#%u: %lld/%lld @%lu -> ENABLE: %x, CON: %x, PERIOD: %llx, DUTY: %llx\n",
+ pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, clk_rate,
+ enable, clkdiv, cnt_period, cnt_duty);
+
+ *wfhw = (typeof(*wfhw)){
+ .enable = enable,
+ .con = clkdiv,
+ .width = cnt_period,
+ .thres = cnt_duty,
+ };
+
+ return ret;
+}
+
+static int pwm_mediatek_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm,
+ const void *_wfhw, struct pwm_waveform *wf)
+{
+ const struct pwm_mediatek_waveform *wfhw = _wfhw;
+ struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
+ u32 clkdiv, cnt_period, cnt_duty;
+ unsigned long clk_rate;
+
+ /*
+ * When _wfhw was populated, the clock was on, so .rate is
+ * already set appropriately.
+ */
+ clk_rate = pc->clk_pwms[pwm->hwpwm].rate;
+
+ if (wfhw->enable) {
+ clkdiv = FIELD_GET(PWMCON_CLKDIV, wfhw->con);
+ cnt_period = FIELD_GET(PWMDWIDTH_PERIOD, wfhw->width);
+ cnt_duty = FIELD_GET(PWMTHRES_DUTY, wfhw->thres);
- if (pc->soc->pwm45_fixup && pwm->hwpwm > 2) {
/*
- * PWM[4,5] has distinct offset for PWMDWIDTH and PWMTHRES
- * from the other PWMs on MT7623.
+ * cnt_period is a 13 bit value, NSEC_PER_SEC is 30 bits wide
+ * and clkdiv is less than 8, so the multiplication doesn't
+ * overflow an u64.
*/
- reg_width = PWM45DWIDTH_FIXUP;
- reg_thres = PWM45THRES_FIXUP;
- }
+ *wf = (typeof(*wf)){
+ .period_length_ns =
+ DIV_ROUND_UP_ULL((u64)(cnt_period + 1) * NSEC_PER_SEC << clkdiv, clk_rate),
+ .duty_length_ns =
+ DIV_ROUND_UP_ULL((u64)(cnt_duty + 1) * NSEC_PER_SEC << clkdiv, clk_rate),
+ };
+ } else {
+ clkdiv = 0;
+ cnt_period = 0;
+ cnt_duty = 0;
- pwm_mediatek_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | clkdiv);
- pwm_mediatek_writel(pc, pwm->hwpwm, reg_width, cnt_period);
+ /*
+ * .enable = 0 is also used for too small duty_cycle values, so
+ * report the HW as being enabled to communicate the minimal
+ * period.
+ */
+ *wf = (typeof(*wf)){
+ .period_length_ns =
+ DIV_ROUND_UP_ULL(NSEC_PER_SEC, clk_rate),
+ .duty_length_ns = 0,
+ };
+ };
+
+ dev_dbg(&chip->dev, "pwm#%u: ENABLE: %x, CLKDIV: %x, PERIOD: %x, DUTY: %x @%lu -> %lld/%lld\n",
+ pwm->hwpwm, wfhw->enable, clkdiv, cnt_period, cnt_duty, clk_rate,
+ wf->duty_length_ns, wf->period_length_ns);
+
+ return 0;
+}
+
+static int pwm_mediatek_read_waveform(struct pwm_chip *chip,
+ struct pwm_device *pwm, void *_wfhw)
+{
+ struct pwm_mediatek_waveform *wfhw = _wfhw;
+ struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
+ u32 enable, clkdiv, cnt_period, cnt_duty;
+ u32 reg_width = PWMDWIDTH, reg_thres = PWMTHRES;
+ int ret;
+
+ ret = pwm_mediatek_clk_enable(pc, pwm->hwpwm);
+ if (ret < 0)
+ return ret;
+
+ enable = readl(pc->regs) & BIT(pwm->hwpwm);
if (enable) {
- pwm_mediatek_writel(pc, pwm->hwpwm, reg_thres, cnt_duty);
- pwm_mediatek_enable(chip, pwm);
+ if (pc->soc->pwm45_fixup && pwm->hwpwm > 2) {
+ /*
+ * PWM[4,5] has distinct offset for PWMDWIDTH and PWMTHRES
+ * from the other PWMs on MT7623.
+ */
+ reg_width = PWM45DWIDTH_FIXUP;
+ reg_thres = PWM45THRES_FIXUP;
+ }
+
+ clkdiv = FIELD_GET(PWMCON_CLKDIV, pwm_mediatek_readl(pc, pwm->hwpwm, PWMCON));
+ cnt_period = FIELD_GET(PWMDWIDTH_PERIOD, pwm_mediatek_readl(pc, pwm->hwpwm, reg_width));
+ cnt_duty = FIELD_GET(PWMTHRES_DUTY, pwm_mediatek_readl(pc, pwm->hwpwm, reg_thres));
+
+ *wfhw = (typeof(*wfhw)){
+ .enable = enable,
+ .con = BIT(15) | clkdiv,
+ .width = cnt_period,
+ .thres = cnt_duty,
+ };
} else {
- pwm_mediatek_disable(chip, pwm);
+ *wfhw = (typeof(*wfhw)){
+ .enable = 0,
+ };
+ }
+
+ pwm_mediatek_clk_disable(pc, pwm->hwpwm);
+
+ return ret;
+}
+
+static int pwm_mediatek_write_waveform(struct pwm_chip *chip,
+ struct pwm_device *pwm, const void *_wfhw)
+{
+ const struct pwm_mediatek_waveform *wfhw = _wfhw;
+ struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
+ u32 ctrl;
+ int ret;
+
+ ret = pwm_mediatek_clk_enable(pc, pwm->hwpwm);
+ if (ret < 0)
+ return ret;
+
+ ctrl = readl(pc->regs);
+
+ if (wfhw->enable) {
+ u32 reg_width = PWMDWIDTH, reg_thres = PWMTHRES;
+
+ if (pc->soc->pwm45_fixup && pwm->hwpwm > 2) {
+ /*
+ * PWM[4,5] has distinct offset for PWMDWIDTH and PWMTHRES
+ * from the other PWMs on MT7623.
+ */
+ reg_width = PWM45DWIDTH_FIXUP;
+ reg_thres = PWM45THRES_FIXUP;
+ }
+
+ if (!(ctrl & BIT(pwm->hwpwm))) {
+ /*
+ * The clks are already on, just increasing the usage
+ * counter doesn't fail.
+ */
+ ret = pwm_mediatek_clk_enable(pc, pwm->hwpwm);
+ if (unlikely(ret < 0))
+ goto out;
+
+ ctrl |= BIT(pwm->hwpwm);
+ writel(ctrl, pc->regs);
+ }
+
+ /* Make sure we use the bus clock and not the 26MHz clock */
+ if (pc->soc->pwm_ck_26m_sel_reg)
+ writel(0, pc->regs + pc->soc->pwm_ck_26m_sel_reg);
+
+ pwm_mediatek_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | wfhw->con);
+ pwm_mediatek_writel(pc, pwm->hwpwm, reg_width, wfhw->width);
+ pwm_mediatek_writel(pc, pwm->hwpwm, reg_thres, wfhw->thres);
+ } else {
+ if (ctrl & BIT(pwm->hwpwm)) {
+ ctrl &= ~BIT(pwm->hwpwm);
+ writel(ctrl, pc->regs);
+
+ pwm_mediatek_clk_disable(pc, pwm->hwpwm);
+ }
}
out:
@@ -234,93 +382,12 @@ static int pwm_mediatek_config(struct pwm_chip *chip, struct pwm_device *pwm,
return ret;
}
-static int pwm_mediatek_apply(struct pwm_chip *chip, struct pwm_device *pwm,
- const struct pwm_state *state)
-{
- struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
- int err;
-
- if (state->polarity != PWM_POLARITY_NORMAL)
- return -EINVAL;
-
- if (!state->enabled) {
- if (pwm->state.enabled) {
- pwm_mediatek_disable(chip, pwm);
- pwm_mediatek_clk_disable(pc, pwm->hwpwm);
- }
-
- return 0;
- }
-
- err = pwm_mediatek_config(chip, pwm, state->duty_cycle, state->period);
- if (err)
- return err;
-
- if (!pwm->state.enabled)
- err = pwm_mediatek_clk_enable(pc, pwm->hwpwm);
-
- return err;
-}
-
-static int pwm_mediatek_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
- struct pwm_state *state)
-{
- struct pwm_mediatek_chip *pc = to_pwm_mediatek_chip(chip);
- int ret;
- u32 enable;
- u32 reg_width = PWMDWIDTH, reg_thres = PWMTHRES;
-
- if (pc->soc->pwm45_fixup && pwm->hwpwm > 2) {
- /*
- * PWM[4,5] has distinct offset for PWMDWIDTH and PWMTHRES
- * from the other PWMs on MT7623.
- */
- reg_width = PWM45DWIDTH_FIXUP;
- reg_thres = PWM45THRES_FIXUP;
- }
-
- ret = pwm_mediatek_clk_enable(pc, pwm->hwpwm);
- if (ret < 0)
- return ret;
-
- enable = readl(pc->regs);
- if (enable & BIT(pwm->hwpwm)) {
- u32 clkdiv, cnt_period, cnt_duty;
- unsigned long clk_rate;
-
- clk_rate = pc->clk_pwms[pwm->hwpwm].rate;
-
- state->enabled = true;
- state->polarity = PWM_POLARITY_NORMAL;
-
- clkdiv = FIELD_GET(PWMCON_CLKDIV,
- pwm_mediatek_readl(pc, pwm->hwpwm, PWMCON));
- cnt_period = FIELD_GET(PWMDWIDTH_PERIOD,
- pwm_mediatek_readl(pc, pwm->hwpwm, reg_width));
- cnt_duty = FIELD_GET(PWMTHRES_DUTY,
- pwm_mediatek_readl(pc, pwm->hwpwm, reg_thres));
-
- /*
- * cnt_period is a 13 bit value, NSEC_PER_SEC is 30 bits wide
- * and clkdiv is less than 8, so the multiplication doesn't
- * overflow an u64.
- */
- state->period =
- DIV_ROUND_UP_ULL((u64)cnt_period * NSEC_PER_SEC << clkdiv, clk_rate);
- state->duty_cycle =
- DIV_ROUND_UP_ULL((u64)cnt_duty * NSEC_PER_SEC << clkdiv, clk_rate);
- } else {
- state->enabled = false;
- }
-
- pwm_mediatek_clk_disable(pc, pwm->hwpwm);
-
- return ret;
-}
-
static const struct pwm_ops pwm_mediatek_ops = {
- .apply = pwm_mediatek_apply,
- .get_state = pwm_mediatek_get_state,
+ .sizeof_wfhw = sizeof(struct pwm_mediatek_waveform),
+ .round_waveform_tohw = pwm_mediatek_round_waveform_tohw,
+ .round_waveform_fromhw = pwm_mediatek_round_waveform_fromhw,
+ .read_waveform = pwm_mediatek_read_waveform,
+ .write_waveform = pwm_mediatek_write_waveform,
};
static int pwm_mediatek_init_used_clks(struct pwm_mediatek_chip *pc)
base-commit: d80df3e4bc3504eb959d1ea227ff1abe9073fc3f
prerequisite-patch-id: c502c97e7ce053cec32133df9b8d32adfdcb34fb
--
2.51.0
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