[v2,2/3] pwm: stm32: split breakinput apply routine to ease PM support
diff mbox series

Message ID 1570193633-6600-3-git-send-email-fabrice.gasnier@st.com
State Accepted
Headers show
Series
  • Add PM support to STM32 Timer PWM
Related show

Commit Message

Fabrice Gasnier Oct. 4, 2019, 12:53 p.m. UTC
Split breakinput routine that configures STM32 timers 'break' safety
feature upon probe, into two routines:
- stm32_pwm_apply_breakinputs() sets all the break inputs into registers.
- stm32_pwm_probe_breakinputs() probes the device tree break input settings
  before calling stm32_pwm_apply_breakinputs()

This is a precursor patch to ease PM support. Registers content may get
lost during low power. So, break input settings applied upon probe need
to be restored upon resume (e.g. by calling stm32_pwm_apply_breakinputs()).

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
---
 drivers/pwm/pwm-stm32.c | 48 ++++++++++++++++++++++++++++--------------------
 1 file changed, 28 insertions(+), 20 deletions(-)

Comments

Thierry Reding Oct. 16, 2019, 7:03 a.m. UTC | #1
On Fri, Oct 04, 2019 at 02:53:52PM +0200, Fabrice Gasnier wrote:
> Split breakinput routine that configures STM32 timers 'break' safety
> feature upon probe, into two routines:
> - stm32_pwm_apply_breakinputs() sets all the break inputs into registers.
> - stm32_pwm_probe_breakinputs() probes the device tree break input settings
>   before calling stm32_pwm_apply_breakinputs()
> 
> This is a precursor patch to ease PM support. Registers content may get
> lost during low power. So, break input settings applied upon probe need
> to be restored upon resume (e.g. by calling stm32_pwm_apply_breakinputs()).
> 
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
> ---
>  drivers/pwm/pwm-stm32.c | 48 ++++++++++++++++++++++++++++--------------------
>  1 file changed, 28 insertions(+), 20 deletions(-)

Applied, thanks. I've made some minor changes, mostly for consistency
with other drivers and the PWM core. See below.

> diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
> index 359b085..cf8658c 100644
> --- a/drivers/pwm/pwm-stm32.c
> +++ b/drivers/pwm/pwm-stm32.c
> @@ -19,6 +19,12 @@
>  #define CCMR_CHANNEL_MASK  0xFF
>  #define MAX_BREAKINPUT 2
>  
> +struct stm32_breakinput {
> +	u32 index;
> +	u32 level;
> +	u32 filter;
> +};
> +
>  struct stm32_pwm {
>  	struct pwm_chip chip;
>  	struct mutex lock; /* protect pwm config/enable */
> @@ -26,15 +32,11 @@ struct stm32_pwm {
>  	struct regmap *regmap;
>  	u32 max_arr;
>  	bool have_complementary_output;
> +	struct stm32_breakinput breakinput[MAX_BREAKINPUT];
> +	unsigned int nbreakinput;

I changed these to breakinputs and num_breakinputs since they are
slightly more consistent with the naming elsewhere in PWM.

>  	u32 capture[4] ____cacheline_aligned; /* DMA'able buffer */
>  };
>  
> -struct stm32_breakinput {
> -	u32 index;
> -	u32 level;
> -	u32 filter;
> -};
> -
>  static inline struct stm32_pwm *to_stm32_pwm_dev(struct pwm_chip *chip)
>  {
>  	return container_of(chip, struct stm32_pwm, chip);
> @@ -512,15 +514,27 @@ static int stm32_pwm_set_breakinput(struct stm32_pwm *priv,
>  	return (bdtr & bke) ? 0 : -EINVAL;
>  }
>  
> -static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
> +static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv)
> +{
> +	int i, ret = 0;

Made i unsigned int.

> +
> +	for (i = 0; i < priv->nbreakinput && !ret; i++) {
> +		ret = stm32_pwm_set_breakinput(priv,
> +					       priv->breakinput[i].index,
> +					       priv->breakinput[i].level,
> +					       priv->breakinput[i].filter);
> +	}

I thought this was a little odd, so I changed it to explicitly check the
value of ret and return on error.

> +
> +	return ret;

And then this became "return 0;"

> +}
> +
> +static int stm32_pwm_probe_breakinputs(struct stm32_pwm *priv,
>  				       struct device_node *np)
>  {
> -	struct stm32_breakinput breakinput[MAX_BREAKINPUT];
> -	int nb, ret, i, array_size;
> +	int nb, ret, array_size;
>  
>  	nb = of_property_count_elems_of_size(np, "st,breakinput",
>  					     sizeof(struct stm32_breakinput));
> -

Dropped this since it made the code look cluttered.

Thierry

>  	/*
>  	 * Because "st,breakinput" parameter is optional do not make probe
>  	 * failed if it doesn't exist.
> @@ -531,20 +545,14 @@ static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
>  	if (nb > MAX_BREAKINPUT)
>  		return -EINVAL;
>  
> +	priv->nbreakinput = nb;
>  	array_size = nb * sizeof(struct stm32_breakinput) / sizeof(u32);
>  	ret = of_property_read_u32_array(np, "st,breakinput",
> -					 (u32 *)breakinput, array_size);
> +					 (u32 *)priv->breakinput, array_size);
>  	if (ret)
>  		return ret;
>  
> -	for (i = 0; i < nb && !ret; i++) {
> -		ret = stm32_pwm_set_breakinput(priv,
> -					       breakinput[i].index,
> -					       breakinput[i].level,
> -					       breakinput[i].filter);
> -	}
> -
> -	return ret;
> +	return stm32_pwm_apply_breakinputs(priv);
>  }
>  
>  static void stm32_pwm_detect_complementary(struct stm32_pwm *priv)
> @@ -614,7 +622,7 @@ static int stm32_pwm_probe(struct platform_device *pdev)
>  	if (!priv->regmap || !priv->clk)
>  		return -EINVAL;
>  
> -	ret = stm32_pwm_apply_breakinputs(priv, np);
> +	ret = stm32_pwm_probe_breakinputs(priv, np);
>  	if (ret)
>  		return ret;
>  
> -- 
> 2.7.4
>

Patch
diff mbox series

diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c
index 359b085..cf8658c 100644
--- a/drivers/pwm/pwm-stm32.c
+++ b/drivers/pwm/pwm-stm32.c
@@ -19,6 +19,12 @@ 
 #define CCMR_CHANNEL_MASK  0xFF
 #define MAX_BREAKINPUT 2
 
+struct stm32_breakinput {
+	u32 index;
+	u32 level;
+	u32 filter;
+};
+
 struct stm32_pwm {
 	struct pwm_chip chip;
 	struct mutex lock; /* protect pwm config/enable */
@@ -26,15 +32,11 @@  struct stm32_pwm {
 	struct regmap *regmap;
 	u32 max_arr;
 	bool have_complementary_output;
+	struct stm32_breakinput breakinput[MAX_BREAKINPUT];
+	unsigned int nbreakinput;
 	u32 capture[4] ____cacheline_aligned; /* DMA'able buffer */
 };
 
-struct stm32_breakinput {
-	u32 index;
-	u32 level;
-	u32 filter;
-};
-
 static inline struct stm32_pwm *to_stm32_pwm_dev(struct pwm_chip *chip)
 {
 	return container_of(chip, struct stm32_pwm, chip);
@@ -512,15 +514,27 @@  static int stm32_pwm_set_breakinput(struct stm32_pwm *priv,
 	return (bdtr & bke) ? 0 : -EINVAL;
 }
 
-static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
+static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv)
+{
+	int i, ret = 0;
+
+	for (i = 0; i < priv->nbreakinput && !ret; i++) {
+		ret = stm32_pwm_set_breakinput(priv,
+					       priv->breakinput[i].index,
+					       priv->breakinput[i].level,
+					       priv->breakinput[i].filter);
+	}
+
+	return ret;
+}
+
+static int stm32_pwm_probe_breakinputs(struct stm32_pwm *priv,
 				       struct device_node *np)
 {
-	struct stm32_breakinput breakinput[MAX_BREAKINPUT];
-	int nb, ret, i, array_size;
+	int nb, ret, array_size;
 
 	nb = of_property_count_elems_of_size(np, "st,breakinput",
 					     sizeof(struct stm32_breakinput));
-
 	/*
 	 * Because "st,breakinput" parameter is optional do not make probe
 	 * failed if it doesn't exist.
@@ -531,20 +545,14 @@  static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv,
 	if (nb > MAX_BREAKINPUT)
 		return -EINVAL;
 
+	priv->nbreakinput = nb;
 	array_size = nb * sizeof(struct stm32_breakinput) / sizeof(u32);
 	ret = of_property_read_u32_array(np, "st,breakinput",
-					 (u32 *)breakinput, array_size);
+					 (u32 *)priv->breakinput, array_size);
 	if (ret)
 		return ret;
 
-	for (i = 0; i < nb && !ret; i++) {
-		ret = stm32_pwm_set_breakinput(priv,
-					       breakinput[i].index,
-					       breakinput[i].level,
-					       breakinput[i].filter);
-	}
-
-	return ret;
+	return stm32_pwm_apply_breakinputs(priv);
 }
 
 static void stm32_pwm_detect_complementary(struct stm32_pwm *priv)
@@ -614,7 +622,7 @@  static int stm32_pwm_probe(struct platform_device *pdev)
 	if (!priv->regmap || !priv->clk)
 		return -EINVAL;
 
-	ret = stm32_pwm_apply_breakinputs(priv, np);
+	ret = stm32_pwm_probe_breakinputs(priv, np);
 	if (ret)
 		return ret;