[PATCH 0/2] ARM: AM437X: Add rtc clock handling

[PATCH 0/2] ARM: AM437X: Add rtc clock handling

[Keerthy]

The series is applicable for all am437x series of processors.
It adds clock handling support. Boot tested on am437x-gp-evm.

Keerthy (2):
  ARM: dts: AM437x: Add the internal and external clock nodes for rtc
  rtc: omap: Add external clock enabling support

 arch/arm/boot/dts/am4372.dtsi        |  2 ++
 arch/arm/boot/dts/am437x-gp-evm.dts  | 13 +++++++++++
 arch/arm/boot/dts/am437x-idk-evm.dts |  9 ++++++++
 arch/arm/boot/dts/am437x-sk-evm.dts  |  9 ++++++++
 drivers/rtc/rtc-omap.c               | 44 ++++++++++++++++++++++++++++++++++++
 5 files changed, 77 insertions(+)

-- 
1.9.1

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[PATCH 1/2] ARM: dts: AM437x: Add the internal and external clock nodes for rtc

[Keerthy]

rtc can either be supplied from internal 32k clock or external crystal
generated 32k clock. Internal clock is SOC specific and the external
clock is board dependent. Adding the corresponding nodes.

Signed-off-by: Keerthy <j-keerthy-l0cyMroinI0@public.gmane.org>
---
 arch/arm/boot/dts/am4372.dtsi        |  2 ++
 arch/arm/boot/dts/am437x-gp-evm.dts  | 13 +++++++++++++
 arch/arm/boot/dts/am437x-idk-evm.dts |  9 +++++++++
 arch/arm/boot/dts/am437x-sk-evm.dts  |  9 +++++++++
 4 files changed, 33 insertions(+)

diff --git a/arch/arm/boot/dts/am4372.dtsi b/arch/arm/boot/dts/am4372.dtsi
index d99b2ee..484f092 100644
--- a/arch/arm/boot/dts/am4372.dtsi
+++ b/arch/arm/boot/dts/am4372.dtsi
@@ -336,6 +336,8 @@
 			interrupts = <GIC_SPI 75 IRQ_TYPE_LEVEL_HIGH
 				      GIC_SPI 76 IRQ_TYPE_LEVEL_HIGH>;
 			ti,hwmods = "rtc";
+			clocks = <&clk_32768_ck>;
+			clock-names = "int-clk";
 			status = "disabled";
 		};
 
diff --git a/arch/arm/boot/dts/am437x-gp-evm.dts b/arch/arm/boot/dts/am437x-gp-evm.dts
index 215775d..22038f2 100644
--- a/arch/arm/boot/dts/am437x-gp-evm.dts
+++ b/arch/arm/boot/dts/am437x-gp-evm.dts
@@ -112,6 +112,13 @@
 		clock-frequency = <12000000>;
 	};
 
+	/* fixed 32k external oscillator clock */
+	clk_32k_rtc: clk_32k_rtc {
+		#clock-cells = <0>;
+		compatible = "fixed-clock";
+		clock-frequency = <32768>;
+	};
+
 	sound0: sound@0 {
 		compatible = "simple-audio-card";
 		simple-audio-card,name = "AM437x-GP-EVM";
@@ -941,3 +948,9 @@
 	tx-num-evt = <32>;
 	rx-num-evt = <32>;
 };
+
+&rtc {
+	clocks = <&clk_32k_rtc>, <&clk_32768_ck>;
+	clock-names = "ext-clk", "int-clk";
+	status = "okay";
+};
diff --git a/arch/arm/boot/dts/am437x-idk-evm.dts b/arch/arm/boot/dts/am437x-idk-evm.dts
index 37834427..af25801 100644
--- a/arch/arm/boot/dts/am437x-idk-evm.dts
+++ b/arch/arm/boot/dts/am437x-idk-evm.dts
@@ -110,6 +110,13 @@
 			gpios = <&gpio4 2 GPIO_ACTIVE_LOW>;
 		};
 	};
+
+	/* fixed 32k external oscillator clock */
+	clk_32k_rtc: clk_32k_rtc {
+		#clock-cells = <0>;
+		compatible = "fixed-clock";
+		clock-frequency = <32768>;
+	};
 };
 
 &am43xx_pinmux {
@@ -394,6 +401,8 @@
 };
 
 &rtc {
+	clocks = <&clk_32k_rtc>, <&clk_32768_ck>;
+	clock-names = "ext-clk", "int-clk";
 	status = "okay";
 };
 
diff --git a/arch/arm/boot/dts/am437x-sk-evm.dts b/arch/arm/boot/dts/am437x-sk-evm.dts
index 22af448..7da7c2d 100644
--- a/arch/arm/boot/dts/am437x-sk-evm.dts
+++ b/arch/arm/boot/dts/am437x-sk-evm.dts
@@ -24,6 +24,13 @@
 		display0 = &lcd0;
 	};
 
+	/* fixed 32k external oscillator clock */
+	clk_32k_rtc: clk_32k_rtc {
+		#clock-cells = <0>;
+		compatible = "fixed-clock";
+		clock-frequency = <32768>;
+	};
+
 	backlight {
 		compatible = "pwm-backlight";
 		pwms = <&ecap0 0 50000 PWM_POLARITY_INVERTED>;
@@ -697,6 +704,8 @@
 };
 
 &rtc {
+	clocks = <&clk_32k_rtc>, <&clk_32768_ck>;
+	clock-names = "ext-clk", "int-clk";
 	status = "okay";
 };
 
-- 
1.9.1

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[PATCH 2/2] rtc: omap: Add external clock enabling support

[Keerthy]

Configure the clock source to either internal clock
or external clock based on the availability of the clocks.
External clock is preferred as it can be ticking during suspend.

Signed-off-by: Keerthy <j-keerthy-l0cyMroinI0@public.gmane.org>
---
 drivers/rtc/rtc-omap.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index 8b6355f..479f730 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -25,6 +25,7 @@
 #include <linux/of_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/io.h>
+#include <linux/clk.h>
 
 /*
  * The OMAP RTC is a year/month/day/hours/minutes/seconds BCD clock
@@ -107,6 +108,7 @@
 
 /* OMAP_RTC_OSC_REG bit fields: */
 #define OMAP_RTC_OSC_32KCLK_EN		BIT(6)
+#define OMAP_RTC_OSC_SEL_32KCLK_SRC	BIT(3)
 
 /* OMAP_RTC_IRQWAKEEN bit fields: */
 #define OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN	BIT(1)
@@ -136,6 +138,7 @@ struct omap_rtc {
 	int irq_timer;
 	u8 interrupts_reg;
 	bool is_pmic_controller;
+	bool has_ext_clk;
 	const struct omap_rtc_device_type *type;
 };
 
@@ -525,6 +528,7 @@ static int omap_rtc_probe(struct platform_device *pdev)
 {
 	struct omap_rtc	*rtc;
 	struct resource	*res;
+	struct clk *ext_clk, *int_clk;
 	u8 reg, mask, new_ctrl;
 	const struct platform_device_id *id_entry;
 	const struct of_device_id *of_id;
@@ -553,6 +557,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
 	if (rtc->irq_alarm <= 0)
 		return -ENOENT;
 
+	ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
+	if (!IS_ERR(ext_clk)) {
+		rtc->has_ext_clk = true;
+		clk_prepare(ext_clk);
+	} else {
+		int_clk = devm_clk_get(&pdev->dev, "int-clk");
+
+		if (!IS_ERR(int_clk))
+			clk_prepare(int_clk);
+	}
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	rtc->base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(rtc->base))
@@ -627,6 +642,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
 	if (reg != new_ctrl)
 		rtc_write(rtc, OMAP_RTC_CTRL_REG, new_ctrl);
 
+	/*
+	 * If we have the external clock then
+	 * Switch to external clock so we can keep ticking
+	 * acorss suspend
+	 */
+	if (rtc->has_ext_clk) {
+		reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
+		rtc_write(rtc, OMAP_RTC_OSC_REG, reg |
+			  OMAP_RTC_OSC_SEL_32KCLK_SRC);
+	}
+
 	rtc->type->lock(rtc);
 
 	device_init_wakeup(&pdev->dev, true);
@@ -672,6 +698,8 @@ err:
 static int __exit omap_rtc_remove(struct platform_device *pdev)
 {
 	struct omap_rtc *rtc = platform_get_drvdata(pdev);
+	struct clk *ext_clk, *int_clk;
+	u8 reg;
 
 	if (pm_power_off == omap_rtc_power_off &&
 			omap_rtc_power_off_rtc == rtc) {
@@ -681,10 +709,26 @@ static int __exit omap_rtc_remove(struct platform_device *pdev)
 
 	device_init_wakeup(&pdev->dev, 0);
 
+	ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
+	if (!IS_ERR(ext_clk)) {
+		clk_unprepare(ext_clk);
+	} else {
+		int_clk = devm_clk_get(&pdev->dev, "int-clk");
+
+		if (!IS_ERR(int_clk))
+			clk_unprepare(int_clk);
+	}
+
 	rtc->type->unlock(rtc);
 	/* leave rtc running, but disable irqs */
 	rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, 0);
 
+	if (rtc->has_ext_clk) {
+		reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
+		reg &= ~OMAP_RTC_OSC_SEL_32KCLK_SRC;
+		rtc_write(rtc, OMAP_RTC_OSC_REG, reg);
+	}
+
 	rtc->type->lock(rtc);
 
 	/* Disable the clock/module */
-- 
1.9.1

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Re: [PATCH 2/2] rtc: omap: Add external clock enabling support

[Alexandre Belloni]

On 13/08/2015 at 12:37:48 +0530, Keerthy wrote :
> Configure the clock source to either internal clock
> or external clock based on the availability of the clocks.
> External clock is preferred as it can be ticking during suspend.
> 
> Signed-off-by: Keerthy <j-keerthy-l0cyMroinI0@public.gmane.org>
> ---
>  drivers/rtc/rtc-omap.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
> 
> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 8b6355f..479f730 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -25,6 +25,7 @@
>  #include <linux/of_device.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/io.h>
> +#include <linux/clk.h>
>  
>  /*
>   * The OMAP RTC is a year/month/day/hours/minutes/seconds BCD clock
> @@ -107,6 +108,7 @@
>  
>  /* OMAP_RTC_OSC_REG bit fields: */
>  #define OMAP_RTC_OSC_32KCLK_EN		BIT(6)
> +#define OMAP_RTC_OSC_SEL_32KCLK_SRC	BIT(3)
>  
>  /* OMAP_RTC_IRQWAKEEN bit fields: */
>  #define OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN	BIT(1)
> @@ -136,6 +138,7 @@ struct omap_rtc {
>  	int irq_timer;
>  	u8 interrupts_reg;
>  	bool is_pmic_controller;
> +	bool has_ext_clk;
>  	const struct omap_rtc_device_type *type;
>  };
>  
> @@ -525,6 +528,7 @@ static int omap_rtc_probe(struct platform_device *pdev)
>  {
>  	struct omap_rtc	*rtc;
>  	struct resource	*res;
> +	struct clk *ext_clk, *int_clk;
>  	u8 reg, mask, new_ctrl;
>  	const struct platform_device_id *id_entry;
>  	const struct of_device_id *of_id;
> @@ -553,6 +557,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
>  	if (rtc->irq_alarm <= 0)
>  		return -ENOENT;
>  
> +	ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
> +	if (!IS_ERR(ext_clk)) {
> +		rtc->has_ext_clk = true;
> +		clk_prepare(ext_clk);

I'd say this has to be prepare_enable because you are not enabling those
clocks anywhere

> +	} else {
> +		int_clk = devm_clk_get(&pdev->dev, "int-clk");
> +
> +		if (!IS_ERR(int_clk))
> +			clk_prepare(int_clk);
> +	}
> +
>  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>  	rtc->base = devm_ioremap_resource(&pdev->dev, res);
>  	if (IS_ERR(rtc->base))
> @@ -627,6 +642,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
>  	if (reg != new_ctrl)
>  		rtc_write(rtc, OMAP_RTC_CTRL_REG, new_ctrl);
>  
> +	/*
> +	 * If we have the external clock then
> +	 * Switch to external clock so we can keep ticking
> +	 * acorss suspend
> +	 */
> +	if (rtc->has_ext_clk) {
> +		reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
> +		rtc_write(rtc, OMAP_RTC_OSC_REG, reg |
> +			  OMAP_RTC_OSC_SEL_32KCLK_SRC);
> +	}
> +
>  	rtc->type->lock(rtc);
>  
>  	device_init_wakeup(&pdev->dev, true);
> @@ -672,6 +698,8 @@ err:
>  static int __exit omap_rtc_remove(struct platform_device *pdev)
>  {
>  	struct omap_rtc *rtc = platform_get_drvdata(pdev);
> +	struct clk *ext_clk, *int_clk;
> +	u8 reg;
>  
>  	if (pm_power_off == omap_rtc_power_off &&
>  			omap_rtc_power_off_rtc == rtc) {
> @@ -681,10 +709,26 @@ static int __exit omap_rtc_remove(struct platform_device *pdev)
>  
>  	device_init_wakeup(&pdev->dev, 0);
>  
> +	ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
> +	if (!IS_ERR(ext_clk)) {
> +		clk_unprepare(ext_clk);
> +	} else {
> +		int_clk = devm_clk_get(&pdev->dev, "int-clk");
> +
> +		if (!IS_ERR(int_clk))
> +			clk_unprepare(int_clk);
> +	}
> +

You can probably add ext_clk and int_clk to struct omap_rtc and avoid
those devm_clk_get.

>  	rtc->type->unlock(rtc);
>  	/* leave rtc running, but disable irqs */
>  	rtc_write(rtc, OMAP_RTC_INTERRUPTS_REG, 0);
>  
> +	if (rtc->has_ext_clk) {

Then you could also avoid has_ext_clk and simply test rtc->ext_clk.

> +		reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
> +		reg &= ~OMAP_RTC_OSC_SEL_32KCLK_SRC;
> +		rtc_write(rtc, OMAP_RTC_OSC_REG, reg);
> +	}
> +
>  	rtc->type->lock(rtc);
>  
>  	/* Disable the clock/module */
> -- 
> 1.9.1
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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Re: [PATCH 2/2] rtc: omap: Add external clock enabling support

[Vaibhav Hiremath]

On Friday 14 August 2015 02:03 PM, Alexandre Belloni wrote:
> On 13/08/2015 at 12:37:48 +0530, Keerthy wrote :
>> Configure the clock source to either internal clock
>> or external clock based on the availability of the clocks.
>> External clock is preferred as it can be ticking during suspend.
>>
>> Signed-off-by: Keerthy <j-keerthy-l0cyMroinI0@public.gmane.org>
>> ---
>>   drivers/rtc/rtc-omap.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
>>   1 file changed, 44 insertions(+)
>>
>> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
>> index 8b6355f..479f730 100644
>> --- a/drivers/rtc/rtc-omap.c
>> +++ b/drivers/rtc/rtc-omap.c
>> @@ -25,6 +25,7 @@
>>   #include <linux/of_device.h>
>>   #include <linux/pm_runtime.h>
>>   #include <linux/io.h>
>> +#include <linux/clk.h>
>>
>>   /*
>>    * The OMAP RTC is a year/month/day/hours/minutes/seconds BCD clock
>> @@ -107,6 +108,7 @@
>>
>>   /* OMAP_RTC_OSC_REG bit fields: */
>>   #define OMAP_RTC_OSC_32KCLK_EN		BIT(6)
>> +#define OMAP_RTC_OSC_SEL_32KCLK_SRC	BIT(3)
>>
>>   /* OMAP_RTC_IRQWAKEEN bit fields: */
>>   #define OMAP_RTC_IRQWAKEEN_ALARM_WAKEEN	BIT(1)
>> @@ -136,6 +138,7 @@ struct omap_rtc {
>>   	int irq_timer;
>>   	u8 interrupts_reg;
>>   	bool is_pmic_controller;
>> +	bool has_ext_clk;
>>   	const struct omap_rtc_device_type *type;
>>   };
>>
>> @@ -525,6 +528,7 @@ static int omap_rtc_probe(struct platform_device *pdev)
>>   {
>>   	struct omap_rtc	*rtc;
>>   	struct resource	*res;
>> +	struct clk *ext_clk, *int_clk;
>>   	u8 reg, mask, new_ctrl;
>>   	const struct platform_device_id *id_entry;
>>   	const struct of_device_id *of_id;
>> @@ -553,6 +557,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
>>   	if (rtc->irq_alarm <= 0)
>>   		return -ENOENT;
>>
>> +	ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
>> +	if (!IS_ERR(ext_clk)) {
>> +		rtc->has_ext_clk = true;
>> +		clk_prepare(ext_clk);
>
> I'd say this has to be prepare_enable because you are not enabling those
> clocks anywhere
>
>> +	} else {
>> +		int_clk = devm_clk_get(&pdev->dev, "int-clk");
>> +
>> +		if (!IS_ERR(int_clk))
>> +			clk_prepare(int_clk);
>> +	}
>> +
>>   	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>   	rtc->base = devm_ioremap_resource(&pdev->dev, res);
>>   	if (IS_ERR(rtc->base))
>> @@ -627,6 +642,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
>>   	if (reg != new_ctrl)
>>   		rtc_write(rtc, OMAP_RTC_CTRL_REG, new_ctrl);
>>
>> +	/*
>> +	 * If we have the external clock then
>> +	 * Switch to external clock so we can keep ticking
>> +	 * acorss suspend
>> +	 */
>> +	if (rtc->has_ext_clk) {
>> +		reg = rtc_read(rtc, OMAP_RTC_OSC_REG);
>> +		rtc_write(rtc, OMAP_RTC_OSC_REG, reg |
>> +			  OMAP_RTC_OSC_SEL_32KCLK_SRC);
>> +	}
>> +
>>   	rtc->type->lock(rtc);
>>
>>   	device_init_wakeup(&pdev->dev, true);
>> @@ -672,6 +698,8 @@ err:
>>   static int __exit omap_rtc_remove(struct platform_device *pdev)
>>   {
>>   	struct omap_rtc *rtc = platform_get_drvdata(pdev);
>> +	struct clk *ext_clk, *int_clk;
>> +	u8 reg;
>>
>>   	if (pm_power_off == omap_rtc_power_off &&
>>   			omap_rtc_power_off_rtc == rtc) {
>> @@ -681,10 +709,26 @@ static int __exit omap_rtc_remove(struct platform_device *pdev)
>>
>>   	device_init_wakeup(&pdev->dev, 0);
>>
>> +	ext_clk = devm_clk_get(&pdev->dev, "ext-clk");
>> +	if (!IS_ERR(ext_clk)) {
>> +		clk_unprepare(ext_clk);
>> +	} else {
>> +		int_clk = devm_clk_get(&pdev->dev, "int-clk");
>> +
>> +		if (!IS_ERR(int_clk))
>> +			clk_unprepare(int_clk);
>> +	}
>> +
>
> You can probably add ext_clk and int_clk to struct omap_rtc and avoid
> those devm_clk_get.
>


Since both int_clk and ext_clk are mutual exclusive, you can have only 
one variable.


Thanks,
Vaibhav
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Re: [PATCH 2/2] rtc: omap: Add external clock enabling support

[Johan Hovold]

On Thu, Aug 13, 2015 at 12:37:48PM +0530, Keerthy wrote:
> Configure the clock source to either internal clock
> or external clock based on the availability of the clocks.
> External clock is preferred as it can be ticking during suspend.
> 
> Signed-off-by: Keerthy <j-keerthy-l0cyMroinI0@public.gmane.org>

> @@ -627,6 +642,17 @@ static int omap_rtc_probe(struct platform_device *pdev)
>  	if (reg != new_ctrl)
>  		rtc_write(rtc, OMAP_RTC_CTRL_REG, new_ctrl);
>  
> +	/*
> +	 * If we have the external clock then
> +	 * Switch to external clock so we can keep ticking
> +	 * acorss suspend
> +	 */

You should fix up the comment (e.g. stray capitalisation and typo) as
well.

Perhaps reword as

	/*
	 * If we have an external clock then switch to it so we can keep
	 * ticking across suspend.
	 */

Johan
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