linux-kernel - [PATCH v4 3/4] pwm: tiehrpwm: ensure clock and runtime PM are enabled if hardware is active

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Message-Id: <20250419195830.79053-1-rafael.v.volkmer@gmail.com>
Date: Sat, 19 Apr 2025 16:58:30 -0300
From: "Rafael V. Volkmer" <rafael.v.volkmer@...il.com>
To: rafael.v.volkmer@...il.com
Cc: linux-kernel@...r.kernel.org,
	linux-pwm@...r.kernel.org,
	ukleinek@...nel.org
Subject: [PATCH v4 3/4] pwm: tiehrpwm: ensure clock and runtime PM are enabled if hardware is active

During probe, if the hardware is already active, it is not guaranteed
that the clock is enabled. To address this, ehrpwm_pwm_probe() now
checks whether the PWM is enabled and ensures that the necessary
resources are initialized.

Signed-off-by: Rafael V. Volkmer <rafael.v.volkmer@...il.com>
---
 drivers/pwm/pwm-tiehrpwm.c | 46 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)

diff --git a/drivers/pwm/pwm-tiehrpwm.c b/drivers/pwm/pwm-tiehrpwm.c
index cde331a73696..23530d53e177 100644
--- a/drivers/pwm/pwm-tiehrpwm.c
+++ b/drivers/pwm/pwm-tiehrpwm.c
@@ -583,15 +583,50 @@ static int ehrpwm_pwm_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
 	struct ehrpwm_pwm_chip *pc;
+	struct pwm_device *pwm;
+	struct pwm_state state;
 	struct pwm_chip *chip;
 	struct clk *clk;
+	bool tbclk_enabled;
 	int ret;
 
+	u16 aqcsfrc_reg, aqctl_reg;
+
+	u8 csf_bits;
+
 	chip = devm_pwmchip_alloc(&pdev->dev, NUM_PWM_CHANNEL, sizeof(*pc));
 	if (IS_ERR(chip))
 		return PTR_ERR(chip);
 	pc = to_ehrpwm_pwm_chip(chip);
 
+	pwm = &chip->pwms[0];
+
+	if (pwm->hwpwm == 0) {
+		aqcsfrc_reg = readw(pc->mmio_base + AQCSFRC);
+		csf_bits = FIELD_GET(AQCSFRC_CSFA_MASK, aqcsfrc_reg);
+		aqctl_reg = readw(pc->mmio_base + AQCTLA);
+	} else {
+		aqcsfrc_reg = readw(pc->mmio_base + AQCSFRC);
+		csf_bits = FIELD_GET(AQCSFRC_CSFB_MASK, aqcsfrc_reg);
+		aqctl_reg = readw(pc->mmio_base + AQCTLB);
+	}
+
+	if (csf_bits)
+		state.enabled = false;
+	else if (aqctl_reg)
+		state.enabled = true;
+	else
+		state.enabled = false;
+
+	if (state.enabled) {
+		ret = clk_enable(pc->tbclk);
+		if (ret) {
+			dev_err_probe(&pdev->dev, ret, "clk_prepare_enable() failed");
+			goto err_pwmchip_remove;
+		}
+		tbclk_enabled = true;
+	}
+
 	clk = devm_clk_get(&pdev->dev, "fck");
 	if (IS_ERR(clk)) {
 		if (of_device_is_compatible(np, "ti,am33xx-ecap")) {
@@ -626,6 +661,15 @@ static int ehrpwm_pwm_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	if (state.enabled) {
+		ret = pm_runtime_get_sync(&pdev->dev);
+		if (ret < 0) {
+			dev_err_probe(&pdev->dev, ret, "pm_runtime_get_sync() failed");
+			clk_disable_unprepare(pc->tbclk);
+			goto err_pwmchip_remove;
+			}
+	}
+
 	ret = pwmchip_add(chip);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
@@ -637,6 +681,8 @@ static int ehrpwm_pwm_probe(struct platform_device *pdev)
 
 	return 0;
 
+err_pwmchip_remove:
+		pwmchip_remove(chip);
 err_clk_unprepare:
 	clk_unprepare(pc->tbclk);
 
-- 
2.25.1