[RFC PATCH 2/3] pwm: axi-pwmgen: add duty offset support

[Trevor Gamblin]

Enable duty_offset feature now that it is supported in the pwm
subsystem. Related macros and struct fields related to duty_offset are
renamed to be consistent.

Signed-off-by: Trevor Gamblin <tgamblin@xxxxxxxxxxxx>
---
 drivers/pwm/pwm-axi-pwmgen.c | 35 +++++++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 8 deletions(-)

diff --git a/drivers/pwm/pwm-axi-pwmgen.c b/drivers/pwm/pwm-axi-pwmgen.c
index 539625c404ac..84ecb12e1e21 100644
--- a/drivers/pwm/pwm-axi-pwmgen.c
+++ b/drivers/pwm/pwm-axi-pwmgen.c
@@ -6,9 +6,9 @@
  * Copyright 2024 Baylibre SAS
  *
  * Limitations:
- * - The writes to registers for period and duty are shadowed until
- *   LOAD_CONFIG is written to AXI_PWMGEN_REG_CONFIG at the end of the
- *   current period.
+ * - The writes to registers for period, duty, and duty_offset are
+ *   shadowed until LOAD_CONFIG is written to AXI_PWMGEN_REG_CONFIG at
+ *   the end of the current period.
  * - Writing LOAD_CONFIG also has the effect of re-synchronizing all
  *   enabled channels, which could cause glitching on other channels. It
  *   is therefore expected that channels are assigned harmonic periods
@@ -34,7 +34,7 @@
 #define AXI_PWMGEN_REG_NPWM		0x14
 #define AXI_PWMGEN_CHX_PERIOD(v, ch)	((v)->period_base + (v)->ch_step * (ch))
 #define AXI_PWMGEN_CHX_DUTY(v, ch)	((v)->duty_base + (v)->ch_step * (ch))
-#define AXI_PWMGEN_CHX_OFFSET(v, ch)	((v)->offset_base + (v)->ch_step * (ch))
+#define AXI_PWMGEN_CHX_DUTY_OFFSET(v, ch)	((v)->duty_offset_base + (v)->ch_step * (ch))
 #define AXI_PWMGEN_REG_CORE_MAGIC_VAL	0x601A3471 /* Identification number to test during setup */
 #define AXI_PWMGEN_LOAD_CONFIG		BIT(1)
 #define AXI_PWMGEN_RESET		BIT(0)
@@ -42,7 +42,7 @@
 struct axi_pwm_variant {
 	u8 period_base;
 	u8 duty_base;
-	u8 offset_base;
+	u8 duty_offset_base;
 	u8 major_version;
 	u8 ch_step;
 };
@@ -62,7 +62,7 @@ static const struct regmap_config axi_pwmgen_regmap_config = {
 static const struct axi_pwm_variant pwmgen_1_00_variant = {
 	.period_base = 0x40,
 	.duty_base = 0x44,
-	.offset_base = 0x48,
+	.duty_offset_base = 0x48,
 	.major_version = 1,
 	.ch_step = 12,
 };
@@ -70,7 +70,7 @@ static const struct axi_pwm_variant pwmgen_1_00_variant = {
 static const struct axi_pwm_variant pwmgen_2_00_variant = {
 	.period_base = 0x40,
 	.duty_base = 0x80,
-	.offset_base = 0xC0,
+	.duty_offset_base = 0xC0,
 	.major_version = 2,
 	.ch_step = 4,
 };
@@ -83,7 +83,7 @@ static int axi_pwmgen_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	unsigned int ch = pwm->hwpwm;
 	struct regmap *regmap = ddata->regmap;
 	const struct axi_pwm_variant *variant = ddata->variant;
-	u64 period_cnt, duty_cnt;
+	u64 period_cnt, duty_cnt, duty_offset_cnt;
 	int ret;
 
 	if (state->polarity != PWM_POLARITY_NORMAL)
@@ -108,6 +108,14 @@ static int axi_pwmgen_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 		ret = regmap_write(regmap, AXI_PWMGEN_CHX_DUTY(variant, ch), duty_cnt);
 		if (ret)
 			return ret;
+
+		duty_offset_cnt = mul_u64_u64_div_u64(state->duty_offset, ddata->clk_rate_hz, NSEC_PER_SEC);
+		if (duty_offset_cnt > UINT_MAX)
+			duty_offset_cnt = UINT_MAX;
+
+		ret = regmap_write(regmap, AXI_PWMGEN_CHX_DUTY_OFFSET(variant, ch), duty_offset_cnt);
+		if (ret)
+			return ret;
 	} else {
 		ret = regmap_write(regmap, AXI_PWMGEN_CHX_PERIOD(variant, ch), 0);
 		if (ret)
@@ -116,6 +124,10 @@ static int axi_pwmgen_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 		ret = regmap_write(regmap, AXI_PWMGEN_CHX_DUTY(variant, ch), 0);
 		if (ret)
 			return ret;
+
+		ret = regmap_write(regmap, AXI_PWMGEN_CHX_DUTY_OFFSET(variant, ch), 0);
+		if (ret)
+			return ret;
 	}
 
 	return regmap_write(regmap, AXI_PWMGEN_REG_CONFIG, AXI_PWMGEN_LOAD_CONFIG);
@@ -145,6 +157,12 @@ static int axi_pwmgen_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	state->duty_cycle = DIV_ROUND_UP_ULL((u64)cnt * NSEC_PER_SEC, ddata->clk_rate_hz);
 
+	ret = regmap_read(regmap, AXI_PWMGEN_CHX_DUTY_OFFSET(variant, ch), &cnt);
+	if (ret)
+		return ret;
+
+	state->duty_offset = DIV_ROUND_UP_ULL((u64)cnt * NSEC_PER_SEC, ddata->clk_rate_hz);
+
 	state->polarity = PWM_POLARITY_NORMAL;
 
 	return 0;
@@ -254,6 +272,7 @@ static int axi_pwmgen_probe(struct platform_device *pdev)
 
 	chip->ops = &axi_pwmgen_pwm_ops;
 	chip->atomic = true;
+	chip->supports_offset = true;
 
 	return devm_pwmchip_add(dev, chip);
 }
-- 
2.44.0