pwm: axi-pwmgen: Implementation of the waveform callbacks

Convert the axi-pwmgen driver to use the new callbacks for hardware
programming.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Tested-by: Trevor Gamblin <tgamblin@baylibre.com>
Link: https://lore.kernel.org/r/922277f07b1d1fb9c9cd915b1ec3fdeec888a916.1726819463.git.u.kleine-koenig@baylibre.com
Signed-off-by: Uwe Kleine-König <ukleinek@kernel.org>

1 files changed, 105 insertions, 43 deletions

diff --git a/drivers/pwm/pwm-axi-pwmgen.c b/drivers/pwm/pwm-axi-pwmgen.c
index b5477659ba18..39d184417c7c 100644
--- a/drivers/pwm/pwm-axi-pwmgen.c
+++ b/drivers/pwm/pwm-axi-pwmgen.c
@@ -23,6 +23,7 @@
 #include <linux/err.h>
 #include <linux/fpga/adi-axi-common.h>
 #include <linux/io.h>
+#include <linux/minmax.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/pwm.h>
@@ -53,81 +54,142 @@ static const struct regmap_config axi_pwmgen_regmap_config = {
 	.max_register = 0xFC,
 };
 
-static int axi_pwmgen_apply(struct pwm_chip *chip, struct pwm_device *pwm,
-			    const struct pwm_state *state)
+/* This represents a hardware configuration for one channel */
+struct axi_pwmgen_waveform {
+	u32 period_cnt;
+	u32 duty_cycle_cnt;
+	u32 duty_offset_cnt;
+};
+
+static int axi_pwmgen_round_waveform_tohw(struct pwm_chip *chip,
+					  struct pwm_device *pwm,
+					  const struct pwm_waveform *wf,
+					  void *_wfhw)
 {
+	struct axi_pwmgen_waveform *wfhw = _wfhw;
 	struct axi_pwmgen_ddata *ddata = pwmchip_get_drvdata(chip);
-	unsigned int ch = pwm->hwpwm;
-	struct regmap *regmap = ddata->regmap;
-	u64 period_cnt, duty_cnt;
-	int ret;
 
-	if (state->polarity != PWM_POLARITY_NORMAL)
-		return -EINVAL;
+	if (wf->period_length_ns == 0) {
+		*wfhw = (struct axi_pwmgen_waveform){
+			.period_cnt = 0,
+			.duty_cycle_cnt = 0,
+			.duty_offset_cnt = 0,
+		};
+	} else {
+		/* With ddata->clk_rate_hz < NSEC_PER_SEC this won't overflow. */
+		wfhw->period_cnt = min_t(u64,
+					 mul_u64_u32_div(wf->period_length_ns, ddata->clk_rate_hz, NSEC_PER_SEC),
+					 U32_MAX);
+
+		if (wfhw->period_cnt == 0) {
+			/*
+			 * The specified period is too short for the hardware.
+			 * Let's round .duty_cycle down to 0 to get a (somewhat)
+			 * valid result.
+			 */
+			wfhw->period_cnt = 1;
+			wfhw->duty_cycle_cnt = 0;
+			wfhw->duty_offset_cnt = 0;
+		} else {
+			wfhw->duty_cycle_cnt = min_t(u64,
+						     mul_u64_u32_div(wf->duty_length_ns, ddata->clk_rate_hz, NSEC_PER_SEC),
+						     U32_MAX);
+			wfhw->duty_offset_cnt = min_t(u64,
+						      mul_u64_u32_div(wf->duty_offset_ns, ddata->clk_rate_hz, NSEC_PER_SEC),
+						      U32_MAX);
+		}
+	}
 
-	if (state->enabled) {
-		period_cnt = mul_u64_u64_div_u64(state->period, ddata->clk_rate_hz, NSEC_PER_SEC);
-		if (period_cnt > UINT_MAX)
-			period_cnt = UINT_MAX;
+	dev_dbg(&chip->dev, "pwm#%u: %lld/%lld [+%lld] @%lu -> PERIOD: %08x, DUTY: %08x, OFFSET: %08x\n",
+		pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
+		ddata->clk_rate_hz, wfhw->period_cnt, wfhw->duty_cycle_cnt, wfhw->duty_offset_cnt);
 
-		if (period_cnt == 0)
-			return -EINVAL;
+	return 0;
+}
 
-		ret = regmap_write(regmap, AXI_PWMGEN_CHX_PERIOD(ch), period_cnt);
-		if (ret)
-			return ret;
+static int axi_pwmgen_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm,
+					     const void *_wfhw, struct pwm_waveform *wf)
+{
+	const struct axi_pwmgen_waveform *wfhw = _wfhw;
+	struct axi_pwmgen_ddata *ddata = pwmchip_get_drvdata(chip);
 
-		duty_cnt = mul_u64_u64_div_u64(state->duty_cycle, ddata->clk_rate_hz, NSEC_PER_SEC);
-		if (duty_cnt > UINT_MAX)
-			duty_cnt = UINT_MAX;
+	wf->period_length_ns = DIV64_U64_ROUND_UP((u64)wfhw->period_cnt * NSEC_PER_SEC,
+					ddata->clk_rate_hz);
 
-		ret = regmap_write(regmap, AXI_PWMGEN_CHX_DUTY(ch), duty_cnt);
-		if (ret)
-			return ret;
-	} else {
-		ret = regmap_write(regmap, AXI_PWMGEN_CHX_PERIOD(ch), 0);
-		if (ret)
-			return ret;
+	wf->duty_length_ns = DIV64_U64_ROUND_UP((u64)wfhw->duty_cycle_cnt * NSEC_PER_SEC,
+					    ddata->clk_rate_hz);
 
-		ret = regmap_write(regmap, AXI_PWMGEN_CHX_DUTY(ch), 0);
-		if (ret)
-			return ret;
-	}
+	wf->duty_offset_ns = DIV64_U64_ROUND_UP((u64)wfhw->duty_offset_cnt * NSEC_PER_SEC,
+					     ddata->clk_rate_hz);
 
-	return regmap_write(regmap, AXI_PWMGEN_REG_CONFIG, AXI_PWMGEN_LOAD_CONFIG);
+	return 0;
 }
 
-static int axi_pwmgen_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
-				struct pwm_state *state)
+static int axi_pwmgen_write_waveform(struct pwm_chip *chip,
+				     struct pwm_device *pwm,
+				     const void *_wfhw)
 {
+	const struct axi_pwmgen_waveform *wfhw = _wfhw;
 	struct axi_pwmgen_ddata *ddata = pwmchip_get_drvdata(chip);
 	struct regmap *regmap = ddata->regmap;
 	unsigned int ch = pwm->hwpwm;
-	u32 cnt;
 	int ret;
 
-	ret = regmap_read(regmap, AXI_PWMGEN_CHX_PERIOD(ch), &cnt);
+	ret = regmap_write(regmap, AXI_PWMGEN_CHX_PERIOD(ch), wfhw->period_cnt);
 	if (ret)
 		return ret;
 
-	state->enabled = cnt != 0;
+	ret = regmap_write(regmap, AXI_PWMGEN_CHX_DUTY(ch), wfhw->duty_cycle_cnt);
+	if (ret)
+		return ret;
 
-	state->period = DIV_ROUND_UP_ULL((u64)cnt * NSEC_PER_SEC, ddata->clk_rate_hz);
+	ret = regmap_write(regmap, AXI_PWMGEN_CHX_OFFSET(ch), wfhw->duty_offset_cnt);
+	if (ret)
+		return ret;
 
-	ret = regmap_read(regmap, AXI_PWMGEN_CHX_DUTY(ch), &cnt);
+	return regmap_write(regmap, AXI_PWMGEN_REG_CONFIG, AXI_PWMGEN_LOAD_CONFIG);
+}
+
+static int axi_pwmgen_read_waveform(struct pwm_chip *chip,
+				    struct pwm_device *pwm,
+				    void *_wfhw)
+{
+	struct axi_pwmgen_waveform *wfhw = _wfhw;
+	struct axi_pwmgen_ddata *ddata = pwmchip_get_drvdata(chip);
+	struct regmap *regmap = ddata->regmap;
+	unsigned int ch = pwm->hwpwm;
+	int ret;
+
+	ret = regmap_read(regmap, AXI_PWMGEN_CHX_PERIOD(ch), &wfhw->period_cnt);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(regmap, AXI_PWMGEN_CHX_DUTY(ch), &wfhw->duty_cycle_cnt);
 	if (ret)
 		return ret;
 
-	state->duty_cycle = DIV_ROUND_UP_ULL((u64)cnt * NSEC_PER_SEC, ddata->clk_rate_hz);
+	ret = regmap_read(regmap, AXI_PWMGEN_CHX_OFFSET(ch), &wfhw->duty_offset_cnt);
+	if (ret)
+		return ret;
 
-	state->polarity = PWM_POLARITY_NORMAL;
+	if (wfhw->duty_cycle_cnt > wfhw->period_cnt)
+		wfhw->duty_cycle_cnt = wfhw->period_cnt;
+
+	/* XXX: is this the actual behaviour of the hardware? */
+	if (wfhw->duty_offset_cnt >= wfhw->period_cnt) {
+		wfhw->duty_cycle_cnt = 0;
+		wfhw->duty_offset_cnt = 0;
+	}
 
 	return 0;
 }
 
 static const struct pwm_ops axi_pwmgen_pwm_ops = {
-	.apply = axi_pwmgen_apply,
-	.get_state = axi_pwmgen_get_state,
+	.sizeof_wfhw = sizeof(struct axi_pwmgen_waveform),
+	.round_waveform_tohw = axi_pwmgen_round_waveform_tohw,
+	.round_waveform_fromhw = axi_pwmgen_round_waveform_fromhw,
+	.read_waveform = axi_pwmgen_read_waveform,
+	.write_waveform = axi_pwmgen_write_waveform,
 };
 
 static int axi_pwmgen_setup(struct regmap *regmap, struct device *dev)