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

["Rafael V. Volkmer" <rafael.v.volkmer@gmail.com>]

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@gmail.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