[04/13] thermal/drivers/hisi: Simplify the temperature/step computation

Message ID 1504082857-21702-4-git-send-email-daniel.lezcano@linaro.org
State Superseded
Headers show
Series
  • Untitled series #3640
Related show

Commit Message

Daniel Lezcano Aug. 30, 2017, 8:47 a.m.
The step and the base temperature are fixed values, we can simplify the
computation by converting the base temperature to milli celsius and use a
pre-computed step value. That saves us a lot of mult + div for nothing at
runtime.

Take also the opportunity to change the function names to be consistent with
the rest of the code.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>

---
 drivers/thermal/hisi_thermal.c | 41 ++++++++++++++++++++++++++++-------------
 1 file changed, 28 insertions(+), 13 deletions(-)

-- 
2.7.4

Comments

Leo Yan Sept. 1, 2017, 2:24 p.m. | #1
On Wed, Aug 30, 2017 at 10:47:28AM +0200, Daniel Lezcano wrote:
> The step and the base temperature are fixed values, we can simplify the

> computation by converting the base temperature to milli celsius and use a

> pre-computed step value. That saves us a lot of mult + div for nothing at

> runtime.

> 

> Take also the opportunity to change the function names to be consistent with

> the rest of the code.

> 

> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>


Reviewed-by: Leo Yan <leo.yan@linaro.org>

Tested-by: Leo Yan <leo.yan@linaro.org>


> ---

>  drivers/thermal/hisi_thermal.c | 41 ++++++++++++++++++++++++++++-------------

>  1 file changed, 28 insertions(+), 13 deletions(-)

> 

> diff --git a/drivers/thermal/hisi_thermal.c b/drivers/thermal/hisi_thermal.c

> index 67db523..b58ad40 100644

> --- a/drivers/thermal/hisi_thermal.c

> +++ b/drivers/thermal/hisi_thermal.c

> @@ -35,8 +35,9 @@

>  #define TEMP0_RST_MSK			(0x1C)

>  #define TEMP0_VALUE			(0x28)

>  

> -#define HISI_TEMP_BASE			(-60)

> +#define HISI_TEMP_BASE			(-60000)

>  #define HISI_TEMP_RESET			(100000)

> +#define HISI_TEMP_STEP			(784)

>  

>  #define HISI_MAX_SENSORS		4

>  #define HISI_DEFAULT_SENSOR		2

> @@ -61,19 +62,32 @@ struct hisi_thermal_data {

>  	void __iomem *regs;

>  };

>  

> -/* in millicelsius */

> -static inline int _step_to_temp(int step)

> +/*

> + * The temperature computation on the tsensor is as follow:

> + *	Unit: millidegree Celsius

> + *	Step: 255/200 (0.7843)

> + *	Temperature base: -60°C

> + *

> + * The register is programmed in temperature steps, every step is 784

> + * millidegree and begins at -60 000 m°C

> + *

> + * The temperature from the steps:

> + *

> + *	Temp = TempBase + (steps x 784)

> + *

> + * and the steps from the temperature:

> + *

> + *	steps = (Temp - TempBase) / 784

> + *

> + */

> +static inline int hisi_thermal_step_to_temp(int step)

>  {

> -	/*

> -	 * Every step equals (1 * 200) / 255 celsius, and finally

> -	 * need convert to millicelsius.

> -	 */

> -	return (HISI_TEMP_BASE * 1000 + (step * 200000 / 255));

> +	return HISI_TEMP_BASE + (step * HISI_TEMP_STEP);

>  }

>  

> -static inline long _temp_to_step(long temp)

> +static inline long hisi_thermal_temp_to_step(long temp)

>  {

> -	return ((temp - HISI_TEMP_BASE * 1000) * 255) / 200000;

> +	return (temp - HISI_TEMP_BASE) / HISI_TEMP_STEP;

>  }

>  

>  static long hisi_thermal_get_sensor_temp(struct hisi_thermal_data *data,

> @@ -99,7 +113,7 @@ static long hisi_thermal_get_sensor_temp(struct hisi_thermal_data *data,

>  	usleep_range(3000, 5000);

>  

>  	val = readl(data->regs + TEMP0_VALUE);

> -	val = _step_to_temp(val);

> +	val = hisi_thermal_step_to_temp(val);

>  

>  	mutex_unlock(&data->thermal_lock);

>  

> @@ -126,10 +140,11 @@ static void hisi_thermal_enable_bind_irq_sensor

>  	writel((sensor->id << 12), data->regs + TEMP0_CFG);

>  

>  	/* enable for interrupt */

> -	writel(_temp_to_step(sensor->thres_temp) | 0x0FFFFFF00,

> +	writel(hisi_thermal_temp_to_step(sensor->thres_temp) | 0x0FFFFFF00,

>  	       data->regs + TEMP0_TH);

>  

> -	writel(_temp_to_step(HISI_TEMP_RESET), data->regs + TEMP0_RST_TH);

> +	writel(hisi_thermal_temp_to_step(HISI_TEMP_RESET),

> +	       data->regs + TEMP0_RST_TH);

>  

>  	/* enable module */

>  	writel(0x1, data->regs + TEMP0_RST_MSK);

> -- 

> 2.7.4

>

Patch

diff --git a/drivers/thermal/hisi_thermal.c b/drivers/thermal/hisi_thermal.c
index 67db523..b58ad40 100644
--- a/drivers/thermal/hisi_thermal.c
+++ b/drivers/thermal/hisi_thermal.c
@@ -35,8 +35,9 @@ 
 #define TEMP0_RST_MSK			(0x1C)
 #define TEMP0_VALUE			(0x28)
 
-#define HISI_TEMP_BASE			(-60)
+#define HISI_TEMP_BASE			(-60000)
 #define HISI_TEMP_RESET			(100000)
+#define HISI_TEMP_STEP			(784)
 
 #define HISI_MAX_SENSORS		4
 #define HISI_DEFAULT_SENSOR		2
@@ -61,19 +62,32 @@  struct hisi_thermal_data {
 	void __iomem *regs;
 };
 
-/* in millicelsius */
-static inline int _step_to_temp(int step)
+/*
+ * The temperature computation on the tsensor is as follow:
+ *	Unit: millidegree Celsius
+ *	Step: 255/200 (0.7843)
+ *	Temperature base: -60°C
+ *
+ * The register is programmed in temperature steps, every step is 784
+ * millidegree and begins at -60 000 m°C
+ *
+ * The temperature from the steps:
+ *
+ *	Temp = TempBase + (steps x 784)
+ *
+ * and the steps from the temperature:
+ *
+ *	steps = (Temp - TempBase) / 784
+ *
+ */
+static inline int hisi_thermal_step_to_temp(int step)
 {
-	/*
-	 * Every step equals (1 * 200) / 255 celsius, and finally
-	 * need convert to millicelsius.
-	 */
-	return (HISI_TEMP_BASE * 1000 + (step * 200000 / 255));
+	return HISI_TEMP_BASE + (step * HISI_TEMP_STEP);
 }
 
-static inline long _temp_to_step(long temp)
+static inline long hisi_thermal_temp_to_step(long temp)
 {
-	return ((temp - HISI_TEMP_BASE * 1000) * 255) / 200000;
+	return (temp - HISI_TEMP_BASE) / HISI_TEMP_STEP;
 }
 
 static long hisi_thermal_get_sensor_temp(struct hisi_thermal_data *data,
@@ -99,7 +113,7 @@  static long hisi_thermal_get_sensor_temp(struct hisi_thermal_data *data,
 	usleep_range(3000, 5000);
 
 	val = readl(data->regs + TEMP0_VALUE);
-	val = _step_to_temp(val);
+	val = hisi_thermal_step_to_temp(val);
 
 	mutex_unlock(&data->thermal_lock);
 
@@ -126,10 +140,11 @@  static void hisi_thermal_enable_bind_irq_sensor
 	writel((sensor->id << 12), data->regs + TEMP0_CFG);
 
 	/* enable for interrupt */
-	writel(_temp_to_step(sensor->thres_temp) | 0x0FFFFFF00,
+	writel(hisi_thermal_temp_to_step(sensor->thres_temp) | 0x0FFFFFF00,
 	       data->regs + TEMP0_TH);
 
-	writel(_temp_to_step(HISI_TEMP_RESET), data->regs + TEMP0_RST_TH);
+	writel(hisi_thermal_temp_to_step(HISI_TEMP_RESET),
+	       data->regs + TEMP0_RST_TH);
 
 	/* enable module */
 	writel(0x1, data->regs + TEMP0_RST_MSK);