[PATCH v2 3/3] pwm: tegra: Implement .get_state()

[Uwe Kleine-König]

The registers of the PWM IP are readable. Use that to implement the
.get_state() callback.

Reviewed-by: Mikko Perttunen <mperttunen@xxxxxxxxxx>
Tested-by: Ola Chr. Vaage <ola.christoffer.vage@xxxxxxxxxxx>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxx>
---
 drivers/pwm/pwm-tegra.c | 48 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

diff --git a/drivers/pwm/pwm-tegra.c b/drivers/pwm/pwm-tegra.c
index b461d3877f43..0520d025c776 100644
--- a/drivers/pwm/pwm-tegra.c
+++ b/drivers/pwm/pwm-tegra.c
@@ -310,8 +310,56 @@ static int tegra_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	return err;
 }
 
+static int tegra_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+			       struct pwm_state *state)
+{
+	struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
+	int rc;
+	u32 val;
+
+	rc = pm_runtime_resume_and_get(pwmchip_parent(chip));
+	if (rc)
+		return rc;
+
+	val = tegra_pwm_readl(pwm, pc->soc->enable_reg);
+	if (val & TEGRA_PWM_ENABLE) {
+		u32 scale, pwm0;
+
+		if (pc->soc->enable_reg != TEGRA_PWM_CSR_0)
+			val = tegra_pwm_readl(pwm, TEGRA_PWM_CSR_0);
+
+		scale = (val >> TEGRA_PWM_SCALE_SHIFT) & ((1 << pc->soc->scale_width) - 1);
+		pwm0 = (val >> TEGRA_PWM_DUTY_SHIFT) & (2 * TEGRA_PWM_DEPTH - 1);
+
+		if (pwm0 > TEGRA_PWM_DEPTH)
+			pwm0 = TEGRA_PWM_DEPTH;
+
+		/*
+		 * scale + 1 is at most 1 << 17, TEGRA_PWM_DEPTH is 256, so the
+		 * multiplication for .period doesn't overflow a u64. With
+		 * pwm0 ≤ TEGRA_PWM_DEPTH, .duty_cycle is also fine.
+		 */
+		*state = (struct pwm_state){
+			.period = DIV64_U64_ROUND_UP((u64)(scale + 1) * TEGRA_PWM_DEPTH * NSEC_PER_SEC, pc->clk_rate),
+			.duty_cycle = DIV64_U64_ROUND_UP((u64)(scale + 1) * pwm0 * NSEC_PER_SEC, pc->clk_rate),
+			.polarity = PWM_POLARITY_NORMAL,
+			.enabled = true,
+		};
+
+	} else {
+		*state = (struct pwm_state){
+			.enabled = false,
+		};
+	}
+
+	pm_runtime_put(pwmchip_parent(chip));
+
+	return 0;
+}
+
 static const struct pwm_ops tegra_pwm_ops = {
 	.apply = tegra_pwm_apply,
+	.get_state = tegra_pwm_get_state,
 };
 
 static int tegra_pwm_probe(struct platform_device *pdev)
-- 
2.47.3