thermal: imx: add necessary clk operation

Thermal sensor needs pll3_usb_otg when measuring temperature, otherwise the temperature read will be incorrect, so need to enable this clk before sensor working, for alarm function, as hardware will take measurement periodically, so we should keep this clk always on once alarm function is enabled. Signed-off-by: Anson Huang <b20788@freescale.com> Acked-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Zhang Rui <rui.zhang@intel.com>

thermal: imx: add necessary clk operation
Thermal sensor needs pll3_usb_otg when measuring temperature, otherwise the temperature read will be incorrect, so need to enable this clk before sensor working, for alarm function, as hardware will take measurement periodically, so we should keep this clk always on once alarm function is enabled. Signed-off-by: Anson Huang <b20788@freescale.com> Acked-by: Shawn Guo <shawn.guo@linaro.org> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Anson Huang · Zhang Rui
1 parent beeb5a1e0e
Showing 2 changed files with 24 additions and 0 deletions Side-by-side Diff
Documentation/devicetree/bindings/thermal/imx-thermal.txt
drivers/thermal/imx_thermal.c
@@ -8,11 +8,15 @@
   calibration data, e.g. OCOTP on imx6q.  The details about calibration data
   can be found in SoC Reference Manual.
  
+Optional properties:
+- clocks : thermal sensor's clock source.
+
 Example:
  
 tempmon {
 	compatible = "fsl,imx6q-tempmon";
 	fsl,tempmon = <&anatop>;
 	fsl,tempmon-data = <&ocotp>;
+	clocks = <&clks 172>;
 };
@@ -7,6 +7,7 @@
  *
  */
  
+#include <linux/clk.h>
 #include <linux/cpu_cooling.h>
 #include <linux/cpufreq.h>
 #include <linux/delay.h>
@@ -73,6 +74,7 @@
 	unsigned long last_temp;
 	bool irq_enabled;
 	int irq;
+	struct clk *thermal_clk;
 };
  
 static void imx_set_alarm_temp(struct imx_thermal_data *data,
@@ -457,6 +459,22 @@
 		return ret;
 	}
  
+	data->thermal_clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(data->thermal_clk)) {
+		dev_warn(&pdev->dev, "failed to get thermal clk!\n");
+	} else {
+		/*
+		 * Thermal sensor needs clk on to get correct value, normally
+		 * we should enable its clk before taking measurement and disable
+		 * clk after measurement is done, but if alarm function is enabled,
+		 * hardware will auto measure the temperature periodically, so we
+		 * need to keep the clk always on for alarm function.
+		 */
+		ret = clk_prepare_enable(data->thermal_clk);
+		if (ret)
+			dev_warn(&pdev->dev, "failed to enable thermal clk: %d\n", ret);
+	}
+
 	/* Enable measurements at ~ 10 Hz */
 	regmap_write(map, TEMPSENSE1 + REG_CLR, TEMPSENSE1_MEASURE_FREQ);
 	measure_freq = DIV_ROUND_UP(32768, 10); /* 10 Hz */
@@ -478,6 +496,8 @@
  
 	/* Disable measurements */
 	regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);
+	if (!IS_ERR(data->thermal_clk))
+		clk_disable_unprepare(data->thermal_clk);
  
 	thermal_zone_device_unregister(data->tz);
 	cpufreq_cooling_unregister(data->cdev);
...	...	@@ -8,11 +8,15 @@
8	8	calibration data, e.g. OCOTP on imx6q. The details about calibration data
9	9	can be found in SoC Reference Manual.
10	10
	11	+Optional properties:
	12	+- clocks : thermal sensor's clock source.
	13	+
11	14	Example:
12	15
13	16	tempmon {
14	17	compatible = "fsl,imx6q-tempmon";
15	18	fsl,tempmon = <&anatop>;
16	19	fsl,tempmon-data = <&ocotp>;
	20	+ clocks = <&clks 172>;
17	21	};
...	...	@@ -7,6 +7,7 @@
7	7	*
8	8	*/
9	9
	10	+#include <linux/clk.h>
10	11	#include <linux/cpu_cooling.h>
11	12	#include <linux/cpufreq.h>
12	13	#include <linux/delay.h>
...	...	@@ -73,6 +74,7 @@
73	74	unsigned long last_temp;
74	75	bool irq_enabled;
75	76	int irq;
	77	+ struct clk *thermal_clk;
76	78	};
77	79
78	80	static void imx_set_alarm_temp(struct imx_thermal_data *data,
...	...	@@ -457,6 +459,22 @@
457	459	return ret;
458	460	}
459	461
	462	+ data->thermal_clk = devm_clk_get(&pdev->dev, NULL);
	463	+ if (IS_ERR(data->thermal_clk)) {
	464	+ dev_warn(&pdev->dev, "failed to get thermal clk!\n");
	465	+ } else {
	466	+ /*
	467	+ * Thermal sensor needs clk on to get correct value, normally
	468	+ * we should enable its clk before taking measurement and disable
	469	+ * clk after measurement is done, but if alarm function is enabled,
	470	+ * hardware will auto measure the temperature periodically, so we
	471	+ * need to keep the clk always on for alarm function.
	472	+ */
	473	+ ret = clk_prepare_enable(data->thermal_clk);
	474	+ if (ret)
	475	+ dev_warn(&pdev->dev, "failed to enable thermal clk: %d\n", ret);
	476	+ }
	477	+
460	478	/* Enable measurements at ~ 10 Hz */
461	479	regmap_write(map, TEMPSENSE1 + REG_CLR, TEMPSENSE1_MEASURE_FREQ);
462	480	measure_freq = DIV_ROUND_UP(32768, 10); /* 10 Hz */
...	...	@@ -478,6 +496,8 @@
478	496
479	497	/* Disable measurements */
480	498	regmap_write(map, TEMPSENSE0 + REG_SET, TEMPSENSE0_POWER_DOWN);
	499	+ if (!IS_ERR(data->thermal_clk))
	500	+ clk_disable_unprepare(data->thermal_clk);
481	501
482	502	thermal_zone_device_unregister(data->tz);
483	503	cpufreq_cooling_unregister(data->cdev);