[PATCH] pwm: imx: switch to the atomic interface and related cleanup

[Boris Brezillon]

This is just a crappy commit to show you how atomic update can be
implemented. Please do not submit the changes as is.

This commit is based on https://lkml.org/lkml/2016/10/7/454.

Signed-off-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxxxxxxx>
---
 drivers/pwm/pwm-imx.c | 262 +++++++++++++++++++++++---------------------------
 1 file changed, 119 insertions(+), 143 deletions(-)

diff --git a/drivers/pwm/pwm-imx.c b/drivers/pwm/pwm-imx.c
index c37d22371848..c6d55f92dc40 100644
--- a/drivers/pwm/pwm-imx.c
+++ b/drivers/pwm/pwm-imx.c
@@ -66,8 +66,6 @@ struct imx_chip {
 static int imx_pwm_config_v1(struct pwm_chip *chip,
 		struct pwm_device *pwm, int duty_ns, int period_ns)
 {
-	struct imx_chip *imx = to_imx_chip(chip);
-
 	/*
 	 * The PWM subsystem allows for exact frequencies. However,
 	 * I cannot connect a scope on my device to the PWM line and
@@ -85,81 +83,118 @@ static int imx_pwm_config_v1(struct pwm_chip *chip,
 	 * both the prescaler (/1 .. /128) and then by CLKSEL
 	 * (/2 .. /16).
 	 */
+	struct imx_chip *imx = to_imx_chip(chip);
 	u32 max = readl(imx->mmio_base + MX1_PWMP);
 	u32 p = max * duty_ns / period_ns;
+	int ret;
+
+	ret = clk_prepare_enable(imx->clk_ipg);
+	if (ret)
+		return ret;
+
 	writel(max - p, imx->mmio_base + MX1_PWMS);
 
+	clk_disable_unprepare(imx->clk_ipg);
+
 	return 0;
 }
 
-static void imx_pwm_set_enable_v1(struct pwm_chip *chip, bool enable)
+static int imx_pwm_enable_v1(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct imx_chip *imx = to_imx_chip(chip);
+	int ret;
 	u32 val;
 
+	ret = clk_prepare_enable(imx->clk_ipg);
+	if (ret)
+		return ret;
+
 	val = readl(imx->mmio_base + MX1_PWMC);
 
-	if (enable)
-		val |= MX1_PWMC_EN;
-	else
-		val &= ~MX1_PWMC_EN;
+	val |= MX1_PWMC_EN;
 
 	writel(val, imx->mmio_base + MX1_PWMC);
+
+	clk_disable_unprepare(imx->clk_per);
+
+	return 0;
 }
 
-static int imx_pwm_config_v2(struct pwm_chip *chip,
-		struct pwm_device *pwm, int duty_ns, int period_ns)
+static void imx_pwm_disable_v1(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+	struct imx_chip *imx = to_imx_chip(chip);
+	u32 val;
+
+	val = readl(imx->mmio_base + MX1_PWMC);
+
+	val &= ~MX1_PWMC_EN;
+
+	writel(val, imx->mmio_base + MX1_PWMC);
+
+	clk_disable_unprepare(imx->clk_per);
+}
+
+static void imx_pwm_wait_fifo_slot(struct pwm_chip *chip, struct pwm_device *pwm)
 {
 	struct imx_chip *imx = to_imx_chip(chip);
 	struct device *dev = chip->dev;
-	unsigned long long c;
-	unsigned long period_cycles, duty_cycles, prescale;
 	unsigned int period_ms;
-	bool enable = pwm_is_enabled(pwm);
-	int wait_count = 0, fifoav;
-	u32 cr, sr;
+	int fifoav;
+	u32 sr;
+
+	sr = readl(imx->mmio_base + MX3_PWMSR);
+	fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
+	if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
+		period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
+					 NSEC_PER_MSEC);
+		msleep(period_ms);
 
-	/*
-	 * i.MX PWMv2 has a 4-word sample FIFO.
-	 * In order to avoid FIFO overflow issue, we do software reset
-	 * to clear all sample FIFO if the controller is disabled or
-	 * wait for a full PWM cycle to get a relinquished FIFO slot
-	 * when the controller is enabled and the FIFO is fully loaded.
-	 */
-	if (enable) {
 		sr = readl(imx->mmio_base + MX3_PWMSR);
-		fifoav = sr & MX3_PWMSR_FIFOAV_MASK;
-		if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
-			period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
-						 NSEC_PER_MSEC);
-			msleep(period_ms);
-
-			sr = readl(imx->mmio_base + MX3_PWMSR);
-			if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
-				dev_warn(dev, "there is no free FIFO slot\n");
-		}
-	} else {
-		writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
-		do {
-			usleep_range(200, 1000);
-			cr = readl(imx->mmio_base + MX3_PWMCR);
-		} while ((cr & MX3_PWMCR_SWR) &&
-			 (wait_count++ < MX3_PWM_SWR_LOOP));
-
-		if (cr & MX3_PWMCR_SWR)
-			dev_warn(dev, "software reset timeout\n");
+		if (fifoav == (sr & MX3_PWMSR_FIFOAV_MASK))
+			dev_warn(dev, "there is no free FIFO slot\n");
 	}
+}
+
+static void imx_pwm_empty_fifo(struct pwm_chip *chip)
+{
+	struct imx_chip *imx = to_imx_chip(chip);
+	struct device *dev = chip->dev;
+	int wait_count = 0;
+	u32 cr;
+
+	writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
+	do {
+		usleep_range(200, 1000);
+		cr = readl(imx->mmio_base + MX3_PWMCR);
+	} while ((cr & MX3_PWMCR_SWR) &&
+		 (wait_count++ < MX3_PWM_SWR_LOOP));
+
+	if (cr & MX3_PWMCR_SWR)
+		dev_warn(dev, "software reset timeout\n");
+}
+
+static int imx_pwm_apply_v2(struct pwm_chip *chip, struct pwm_device *pwm,
+			    struct pwm_state *state)
+{
+	struct imx_chip *imx = to_imx_chip(chip);
+	unsigned long long c;
+	unsigned long period_cycles, duty_cycles, prescale;
+	struct pwm_state cstate;
+	int ret;
+	u32 cr = 0;
+
+	pwm_get_state(pwm, &cstate);
 
 	c = clk_get_rate(imx->clk_per);
-	c = c * period_ns;
+	c = c * state->period;
 	do_div(c, 1000000000);
 	period_cycles = c;
 
 	prescale = period_cycles / 0x10000 + 1;
 
 	period_cycles /= prescale;
-	c = (unsigned long long)period_cycles * duty_ns;
-	do_div(c, period_ns);
+	c = (unsigned long long)period_cycles * state->duty_cycle;
+	do_div(c, state->period);
 	duty_cycles = c;
 
 	/*
@@ -171,134 +206,72 @@ static int imx_pwm_config_v2(struct pwm_chip *chip,
 	else
 		period_cycles = 0;
 
-	writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
-	writel(period_cycles, imx->mmio_base + MX3_PWMPR);
-
-	cr = MX3_PWMCR_PRESCALER(prescale) |
-		MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
-		MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH;
-
-	if (enable)
-		cr |= MX3_PWMCR_EN;
-
-	if (pwm->args.polarity == PWM_POLARITY_INVERSED)
-		cr |= MX3_PWMCR_POUTC;
-
-	writel(cr, imx->mmio_base + MX3_PWMCR);
-
-	return 0;
-}
-
-static void imx_pwm_set_enable_v2(struct pwm_chip *chip, bool enable)
-{
-	struct imx_chip *imx = to_imx_chip(chip);
-	u32 val;
-
-	val = readl(imx->mmio_base + MX3_PWMCR);
-
-	if (enable)
-		val |= MX3_PWMCR_EN;
-	else
-		val &= ~MX3_PWMCR_EN;
-
-	writel(val, imx->mmio_base + MX3_PWMCR);
-}
-
-static int imx_pwm_config(struct pwm_chip *chip,
-		struct pwm_device *pwm, int duty_ns, int period_ns)
-{
-	struct imx_chip *imx = to_imx_chip(chip);
-	int ret;
-
-	ret = clk_prepare_enable(imx->clk_ipg);
-	if (ret)
-		return ret;
-
-	ret = imx->config(chip, pwm, duty_ns, period_ns);
-
-	clk_disable_unprepare(imx->clk_ipg);
-
-	return ret;
-}
-
-static int imx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct imx_chip *imx = to_imx_chip(chip);
-	int ret;
-
 	ret = clk_prepare_enable(imx->clk_per);
 	if (ret)
 		return ret;
 
-	imx->set_enable(chip, true);
-
-	return 0;
-}
+	/* Enable the clock if the PWM is being enabled. */
+	if (state->enabled && !cstate.enabled) {
+		ret = clk_prepare_enable(imx->clk_per);
+		if (ret)
+			return ret;
+	}
 
-static void imx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
-{
-	struct imx_chip *imx = to_imx_chip(chip);
+	/*
+	 * Wait for a free FIFO slot if the PWM is already enabled, and flush
+	 * the FIFO if the PWM was disabled and is about to be enabled.
+	 */
+	if (cstate.enabled)
+		imx_pwm_wait_fifo_slot(chip, pwm);
+	else if (state->enabled)
+		imx_pwm_empty_fifo(chip);
 
-	imx->set_enable(chip, false);
+	writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
+	writel(period_cycles, imx->mmio_base + MX3_PWMPR);
 
-	clk_disable_unprepare(imx->clk_per);
-}
+	cr |= MX3_PWMCR_PRESCALER(prescale) |
+	      MX3_PWMCR_DOZEEN | MX3_PWMCR_WAITEN |
+	      MX3_PWMCR_DBGEN | MX3_PWMCR_CLKSRC_IPG_HIGH;
 
-static int imx_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
-				enum pwm_polarity polarity)
-{
-	struct imx_chip *imx = to_imx_chip(chip);
-	u32 val;
+	if (state->enabled)
+		cr |= MX3_PWMCR_EN;
 
-	if (polarity == pwm->args.polarity)
-		return 0;
+	if (state->polarity == PWM_POLARITY_INVERSED)
+		cr |= MX3_PWMCR_POUTC;
 
-	val = readl(imx->mmio_base + MX3_PWMCR);
 
-	if (polarity == PWM_POLARITY_INVERSED)
-		val |= MX3_PWMCR_POUTC;
-	else
-		val &= ~MX3_PWMCR_POUTC;
+	writel(cr, imx->mmio_base + MX3_PWMCR);
 
-	writel(val, imx->mmio_base + MX3_PWMCR);
+	/* Disable the clock if the PWM is being disabled. */
+	if (!state->enabled && cstate.enabled)
+		clk_disable_unprepare(imx->clk_per);
 
-	dev_dbg(imx->chip.dev, "%s: polarity set to %s\n", __func__,
-		polarity == PWM_POLARITY_INVERSED ? "inverted" : "normal");
+	clk_disable_unprepare(imx->clk_per);
 
 	return 0;
 }
 
 static struct pwm_ops imx_pwm_ops_v1 = {
-	.enable = imx_pwm_enable,
-	.disable = imx_pwm_disable,
-	.config = imx_pwm_config,
+	.enable = imx_pwm_enable_v1,
+	.disable = imx_pwm_disable_v1,
+	.config = imx_pwm_config_v1,
 	.owner = THIS_MODULE,
 };
 
 static struct pwm_ops imx_pwm_ops_v2 = {
-	.enable = imx_pwm_enable,
-	.disable = imx_pwm_disable,
-	.set_polarity = imx_pwm_set_polarity,
-	.config = imx_pwm_config,
+	.apply = imx_pwm_apply_v2,
 	.owner = THIS_MODULE,
 };
 
 struct imx_pwm_data {
-	int (*config)(struct pwm_chip *chip,
-		struct pwm_device *pwm, int duty_ns, int period_ns);
-	void (*set_enable)(struct pwm_chip *chip, bool enable);
 	struct pwm_ops *pwm_ops;
 };
 
 static struct imx_pwm_data imx_pwm_data_v1 = {
-	.config = imx_pwm_config_v1,
-	.set_enable = imx_pwm_set_enable_v1,
 	.pwm_ops = &imx_pwm_ops_v1,
 };
 
 static struct imx_pwm_data imx_pwm_data_v2 = {
-	.config = imx_pwm_config_v2,
-	.set_enable = imx_pwm_set_enable_v2,
 	.pwm_ops = &imx_pwm_ops_v2,
 };
 
@@ -317,6 +290,7 @@ static int imx_pwm_probe(struct platform_device *pdev)
 	struct imx_chip *imx;
 	struct resource *r;
 	int ret = 0;
+	u32 cells;
 
 	if (!of_id)
 		return -ENODEV;
@@ -346,7 +320,12 @@ static int imx_pwm_probe(struct platform_device *pdev)
 	imx->chip.base = -1;
 	imx->chip.npwm = 1;
 	imx->chip.can_sleep = true;
-	if (data->pwm_ops->set_polarity) {
+
+	ret = of_property_read_u32(pdev->dev.of_node, "#pwm-cells", &cells);
+	if (ret)
+		return ret;
+
+	if (cells == 3) {
 		dev_dbg(&pdev->dev, "PWM supports output inversion\n");
 		imx->chip.of_xlate = of_pwm_xlate_with_flags;
 		imx->chip.of_pwm_n_cells = 3;
@@ -357,9 +336,6 @@ static int imx_pwm_probe(struct platform_device *pdev)
 	if (IS_ERR(imx->mmio_base))
 		return PTR_ERR(imx->mmio_base);
 
-	imx->config = data->config;
-	imx->set_enable = data->set_enable;
-
 	ret = pwmchip_add(&imx->chip);
 	if (ret < 0)
 		return ret;
-- 
2.7.4