pwm: mediatek: Convert to waveform API

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@baylibre.com>
Link: https://patch.msgid.link/20251013114258.149260-2-u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

Author: ukleinek

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);
-}
+struct pwm_mediatek_waveform {
+	u32 enable;
+	u32 con;
+	u32 width;
+	u32 thres;
+};
 
-static int pwm_mediatek_config(struct pwm_chip *chip, struct pwm_device *pwm,
-			       u64 duty_ns, u64 period_ns)
+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,
+		};
 
-	clk_rate = pc->clk_pwms[pwm->hwpwm].rate;
+		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;
 
-	/* 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);
+		pc->clk_pwms[pwm->hwpwm].rate = clk_get_rate(clk);
 
-	cnt_period = mul_u64_u64_div_u64(period_ns, clk_rate, NSEC_PER_SEC);
+		clk_disable_unprepare(clk);
+	}
+
+	clk_rate = pc->clk_pwms[pwm->hwpwm].rate;
+	if (clk_rate == 0 || clk_rate > 1000000000)
+		return -EINVAL;
+
+	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;
 
@@ -206,121 +207,187 @@ 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);
 
-	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;
-	}
+	*wfhw = (typeof(*wfhw)){
+		.enable = enable,
+		.con = clkdiv,
+		.width = cnt_period,
+		.thres = cnt_duty,
+	};
 
-	pwm_mediatek_writel(pc, pwm->hwpwm, PWMCON, BIT(15) | clkdiv);
-	pwm_mediatek_writel(pc, pwm->hwpwm, reg_width, cnt_period);
+	return ret;
+}
 
-	if (enable) {
-		pwm_mediatek_writel(pc, pwm->hwpwm, reg_thres, cnt_duty);
-		pwm_mediatek_enable(chip, pwm);
+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);
+
+		/*
+		 * 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.
+		 */
+		*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 {
-		pwm_mediatek_disable(chip, pwm);
-	}
+		clkdiv = 0;
+		cnt_period = 0;
+		cnt_duty = 0;
 
-out:
-	pwm_mediatek_clk_disable(pc, pwm->hwpwm);
+		/*
+		 * .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,
+		};
+	};
 
-	return ret;
+	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_apply(struct pwm_chip *chip, struct pwm_device *pwm,
-			      const struct pwm_state *state)
+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);
-	int err;
+	u32 enable, clkdiv, cnt_period, cnt_duty;
+	u32 reg_width = PWMDWIDTH, reg_thres = PWMTHRES;
+	int ret;
 
-	if (state->polarity != PWM_POLARITY_NORMAL)
-		return -EINVAL;
+	ret = pwm_mediatek_clk_enable(pc, pwm->hwpwm);
+	if (ret < 0)
+		return ret;
 
-	if (!state->enabled) {
-		if (pwm->state.enabled) {
-			pwm_mediatek_disable(chip, pwm);
-			pwm_mediatek_clk_disable(pc, pwm->hwpwm);
+	enable = readl(pc->regs) & BIT(pwm->hwpwm);
+
+	if (enable) {
+		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;
 		}
 
-		return 0;
-	}
+		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));
 
-	err = pwm_mediatek_config(chip, pwm, state->duty_cycle, state->period);
-	if (err)
-		return err;
+		*wfhw = (typeof(*wfhw)){
+			.enable = enable,
+			.con = BIT(15) | clkdiv,
+			.width = cnt_period,
+			.thres = cnt_duty,
+		};
+	} else {
+		*wfhw = (typeof(*wfhw)){
+			.enable = 0,
+		};
+	}
 
-	if (!pwm->state.enabled)
-		err = pwm_mediatek_clk_enable(pc, pwm->hwpwm);
+	pwm_mediatek_clk_disable(pc, pwm->hwpwm);
 
-	return err;
+	return ret;
 }
 
-static int pwm_mediatek_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				  struct pwm_state *state)
+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;
-	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;
+	ctrl = readl(pc->regs);
 
-		clk_rate = pc->clk_pwms[pwm->hwpwm].rate;
+	if (wfhw->enable) {
+		u32 reg_width = PWMDWIDTH, reg_thres = PWMTHRES;
 
-		state->enabled = true;
-		state->polarity = PWM_POLARITY_NORMAL;
+		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));
+		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);
+		}
 
-		/*
-		 * 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);
+		/* 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 {
-		state->enabled = false;
+		if (ctrl & BIT(pwm->hwpwm)) {
+			ctrl &= ~BIT(pwm->hwpwm);
+			writel(ctrl, pc->regs);
+
+			pwm_mediatek_clk_disable(pc, pwm->hwpwm);
+		}
 	}
 
+out:
 	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)