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Add SNVS clock support to rtc-snvs driver

PATCH RESEND Superseded Sanchayan Maity 4 participants 9 messages Dec 3, 2014 – Dec 5, 2014 Real time clock (RTC)

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Sanchayan Maity

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#0 lore raw

PATCH RESEND v2 1/1 Add SNVS clock support to rtc-snvs driver

For v2:
As such this patch remains the same, but is being resend and in isolation after the previous discussions here.
https://lkml.org/lkml/2014/11/7/295

Since the changes on rtc-snvs.c will need to go through the rtc subsystem tree and the DT changes cannot be applied by Shawn, till this driver patch gets mainlined, this driver patch I am sending by itself without the DT changes send earlier.

The first version of the patches were send quiet a while back.
https://lkml.org/lkml/2014/9/26/492

The reason for sending this v2 of the patches late was to prevent any changes midway to the VF dts patches being tried with the below commit.
https://lkml.org/lkml/2014/10/22/605

Changes since v1:
The clock enable and disable functions for the SNVS are now optional and only enable/disable it, if it has been defined in the device tree node. Instead of failing and returning error as in the earlier set of patches, this makes sure that the driver does not break for the other i.MX devices for which the clock has not been defined and enabled elsewhere.

Sanchayan Maity (1):
drivers/rtc/rtc-snvs: Add clock support

 drivers/rtc/rtc-snvs.c |   34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)
Signature · 1 line
1.7.9.5
author
#1 lore raw

PATCH RESEND v2 1/1 drivers/rtc/rtc-snvs: Add clock support

This patch adds clock enable and disable support for the SNVS peripheral, which is required for using the RTC within the SNVS block.

The clock is not strictly enforced, as this would break the i.MX devices. The clocking for the i.MX devices seems to be enabled elsewhere and enabling RTC SNVS for Vybrid results in a crash. This patch adds the clock support but also makes it optional so Vybrid platform can use the clock if defined while making sure not to break i.MX .

Signed-off-by Sanchayan Maity <[email protected]>
---
 drivers/rtc/rtc-snvs.c |   34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)
drivers/rtc/rtc-snvs.c +32 -2
index fa384fe..d4a6512 100644
@@ -17,6 +17,7 @@
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
+#include <linux/clk.h>
 
 /* These register offsets are relative to LP (Low Power) range */
 #define SNVS_LPCR		0x04

@@ -39,6 +40,7 @@ struct snvs_rtc_data {
 	void __iomem *ioaddr;
 	int irq;
 	spinlock_t lock;
+	struct clk *clk;
 };
 
 static u32 rtc_read_lp_counter(void __iomem *ioaddr)

@@ -260,6 +262,18 @@ static int snvs_rtc_probe(struct platform_device *pdev)
 	if (data->irq < 0)
 		return data->irq;
 
+	data->clk = devm_clk_get(&pdev->dev, "snvs-rtc");
+	if (IS_ERR(data->clk)) {
+		data->clk = NULL;
+	} else {
+		ret = clk_prepare_enable(data->clk);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"Could not prepare or enable the snvs clock\n");
+			return ret;
+		}
+	}
+
 	platform_set_drvdata(pdev, data);
 
 	spin_lock_init(&data->lock);

@@ -280,7 +294,7 @@ static int snvs_rtc_probe(struct platform_device *pdev)
 	if (ret) {
 		dev_err(&pdev->dev, "failed to request irq %d: %d\n",
 			data->irq, ret);
-		return ret;
+		goto error_rtc_device_register;
 	}
 
 	data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,

@@ -288,10 +302,16 @@ static int snvs_rtc_probe(struct platform_device *pdev)
 	if (IS_ERR(data->rtc)) {
 		ret = PTR_ERR(data->rtc);
 		dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
-		return ret;
+		goto error_rtc_device_register;
 	}
 
 	return 0;
+
+error_rtc_device_register:
+	if (data->clk)
+		clk_disable_unprepare(data->clk);
+
+	return ret;
 }
 
 #ifdef CONFIG_PM_SLEEP

@@ -302,16 +322,26 @@ static int snvs_rtc_suspend(struct device *dev)
 	if (device_may_wakeup(dev))
 		enable_irq_wake(data->irq);
 
+	if (data->clk)
+		clk_disable_unprepare(data->clk);
+
 	return 0;
 }
 
 static int snvs_rtc_resume(struct device *dev)
 {
 	struct snvs_rtc_data *data = dev_get_drvdata(dev);
+	int ret;
 
 	if (device_may_wakeup(dev))
 		disable_irq_wake(data->irq);
 
+	if (data->clk) {
+		ret = clk_prepare_enable(data->clk);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }
 #endif
Signature · 1 line
1.7.9.5
Acked-by on v2 1/1
#2 lore raw

Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

Quoted 100 lines · Sanchayan Maity

This patch adds clock enable and disable support for the SNVS peripheral, which is required for using the RTC within the SNVS block.

The clock is not strictly enforced, as this would break the i.MX devices. The clocking for the i.MX devices seems to be enabled elsewhere and enabling RTC SNVS for Vybrid results in a crash. This patch adds the clock support but also makes it optional so Vybrid platform can use the clock if defined while making sure not to break i.MX .

Signed-off-by Sanchayan Maity <[email protected]>
---
 drivers/rtc/rtc-snvs.c |   34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)
drivers/rtc/rtc-snvs.c +26 -2
index fa384fe..d4a6512 100644
@@ -17,6 +17,7 @@
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/rtc.h>
+#include <linux/clk.h>
 
 /* These register offsets are relative to LP (Low Power) range */
 #define SNVS_LPCR		0x04

@@ -39,6 +40,7 @@ struct snvs_rtc_data {
 	void __iomem *ioaddr;
 	int irq;
 	spinlock_t lock;
+	struct clk *clk;
 };
 
 static u32 rtc_read_lp_counter(void __iomem *ioaddr)

@@ -260,6 +262,18 @@ static int snvs_rtc_probe(struct platform_device *pdev)
 	if (data->irq < 0)
 		return data->irq;
 
+	data->clk = devm_clk_get(&pdev->dev, "snvs-rtc");
+	if (IS_ERR(data->clk)) {
+		data->clk = NULL;
+	} else {
+		ret = clk_prepare_enable(data->clk);
+		if (ret) {
+			dev_err(&pdev->dev,
+				"Could not prepare or enable the snvs clock\n");
+			return ret;
+		}
+	}
+
 	platform_set_drvdata(pdev, data);
 
 	spin_lock_init(&data->lock);

@@ -280,7 +294,7 @@ static int snvs_rtc_probe(struct platform_device *pdev)
 	if (ret) {
 		dev_err(&pdev->dev, "failed to request irq %d: %d\n",
 			data->irq, ret);
-		return ret;
+		goto error_rtc_device_register;
 	}
 
 	data->rtc = devm_rtc_device_register(&pdev->dev, pdev->name,

@@ -288,10 +302,16 @@ static int snvs_rtc_probe(struct platform_device *pdev)
 	if (IS_ERR(data->rtc)) {
 		ret = PTR_ERR(data->rtc);
 		dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
-		return ret;
+		goto error_rtc_device_register;
 	}
 
 	return 0;
+
+error_rtc_device_register:
+	if (data->clk)
+		clk_disable_unprepare(data->clk);
+
+	return ret;
 }
 
 #ifdef CONFIG_PM_SLEEP

@@ -302,16 +322,26 @@ static int snvs_rtc_suspend(struct device *dev)
 	if (device_may_wakeup(dev))
 		enable_irq_wake(data->irq);
 
+	if (data->clk)
+		clk_disable_unprepare(data->clk);
+
 	return 0;
 }
 
 static int snvs_rtc_resume(struct device *dev)
 {
 	struct snvs_rtc_data *data = dev_get_drvdata(dev);
+	int ret;
 
 	if (device_may_wakeup(dev))
 		disable_irq_wake(data->irq);

drivers/rtc/rtc-snvs.c static int snvs_rtc_suspend(struct device *dev) · line 347

Quoted 10 lines
drivers/rtc/rtc-snvs.c +6 -0
 
+	if (data->clk) {
+		ret = clk_prepare_enable(data->clk);
+		if (ret)
+			return ret;
+	}
+
 	return 0;
 }
 #endif
Acked-by Stefan Agner <[email protected]>

--
Stefan

Acked-by on v2 1/1
#3 lore raw

Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

In reply to Sanchayan Maity
Quoted 9 lines · On Wed, 3 Dec 2014 11:28:55 +0530 Sanchayan Maity <[email protected]>…

The clock is not strictly enforced, as this would break the i.MX devices. The clocking for the i.MX devices seems to be enabled elsewhere and enabling RTC SNVS for Vybrid results in a crash. This patch adds the clock support but also makes it optional so Vybrid platform can use the clock if defined while making sure not to break i.MX .

Signed-off-by Sanchayan Maity <[email protected]>
Acked-by Alessandro Zummo <[email protected]>
Signature · 6 lines
 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it
#4 lore raw

Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

Quoted 11 lines · Alessandro Zummo
Quoted 8 lines · On Wed, 3 Dec 2014 11:28:55 +0530 Sanchayan Maity <[email protected]>…

The clock is not strictly enforced, as this would break the i.MX devices. The clocking for the i.MX devices seems to be enabled elsewhere and enabling RTC SNVS for Vybrid results in a crash. This patch adds the clock support but also makes it optional so Vybrid platform can use the clock if defined while making sure not to break i.MX .

Quoted 4 lines
Quoted 1 line
Signed-off-by Sanchayan Maity <[email protected]>
Acked-by Alessandro Zummo <[email protected]>

Through which tree is this going upstream?

--
Stefan

#5 lore raw

Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

Quoted 3 lines · On Thu, 04 Dec 2014 13:29:58 +0100 Stefan Agner <[email protected]> wrote:
Quoted 1 line
Acked-by Alessandro Zummo <[email protected]>

Through which tree is this going upstream?

Andrew usually picks up those small patches, unless there's a more appropriate tree.

Signature · 6 lines
 Best regards,

 Alessandro Zummo,
  Tower Technologies - Torino, Italy

  http://www.towertech.it
#6 lore raw

Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

In reply to Sanchayan Maity
Quoted 12 lines · On Wed, 3 Dec 2014 11:28:55 +0530 Sanchayan Maity <[email protected]>…

This patch adds clock enable and disable support for the SNVS peripheral, which is required for using the RTC within the SNVS block.

The clock is not strictly enforced, as this would break the i.MX devices. The clocking for the i.MX devices seems to be enabled elsewhere and enabling RTC SNVS for Vybrid results in a crash. This patch adds the clock support but also makes it optional so Vybrid platform can use the clock if defined while making sure not to break i.MX .

Quoted 1 line

...

I assume this hasn't been tested with CONFIG_HAVE_CLK=n. It all *looks* OK, but the clk API does its tests for clk==NULL in some very deep places.

drivers/rtc/rtc-snvs.c

Quoted 2 lines
drivers/rtc/rtc-snvs.c +0 -0

.

Quoted 16 lines

...

drivers/rtc/rtc-snvs.c +5 -1
@@ -288,10 +302,16 @@ static int snvs_rtc_probe(struct platform_device *pdev)
 	if (IS_ERR(data->rtc)) {
 		ret = PTR_ERR(data->rtc);
 		dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
-		return ret;
+		goto error_rtc_device_register;
 	}
 
 	return 0;
+
+error_rtc_device_register:
+	if (data->clk)
+		clk_disable_unprepare(data->clk);
Quoted 1 line

From my reading, there's no need to test data->clk here -

clk_disable_unprepare() handles that.

It doesn't hurt to test it - a reasonable approach would be to look around at what other users of the clk API are doing, and do that.

drivers/rtc/rtc-snvs.c static int snvs_rtc_suspend(struct device *dev) · line 326

Quoted 10 lines
drivers/rtc/rtc-snvs.c +3 -0
+	return ret;
 }
 
 #ifdef CONFIG_PM_SLEEP

@@ -302,16 +322,26 @@ static int snvs_rtc_suspend(struct device *dev)
 	if (device_may_wakeup(dev))
 		enable_irq_wake(data->irq);
 
+	if (data->clk)
+		clk_disable_unprepare(data->clk);

Ditto.

Quoted 6 lines
drivers/rtc/rtc-snvs.c +0 -0
 	return 0;
 }
 
 static int snvs_rtc_resume(struct device *dev)
 {
 	struct snvs_rtc_data *data = dev_get_drvdata(dev);

drivers/rtc/rtc-snvs.c static int snvs_rtc_suspend(struct device *dev) · line 343

Quoted 10 lines
drivers/rtc/rtc-snvs.c +6 -0
+	int ret;
 
 	if (device_may_wakeup(dev))
 		disable_irq_wake(data->irq);
 
+	if (data->clk) {
+		ret = clk_prepare_enable(data->clk);
+		if (ret)
+			return ret;
+	}

It could be omitted here also.

Quoted 3 lines
drivers/rtc/rtc-snvs.c +0 -0
 	return 0;
 }
 #endif
#7 lore raw

Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

Quoted 68 lines · Andrew Morton
Quoted 12 lines · On Wed, 3 Dec 2014 11:28:55 +0530 Sanchayan Maity <[email protected]>…

This patch adds clock enable and disable support for the SNVS peripheral, which is required for using the RTC within the SNVS block.

The clock is not strictly enforced, as this would break the i.MX devices. The clocking for the i.MX devices seems to be enabled elsewhere and enabling RTC SNVS for Vybrid results in a crash. This patch adds the clock support but also makes it optional so Vybrid platform can use the clock if defined while making sure not to break i.MX .

Quoted 1 line

...

I assume this hasn't been tested with CONFIG_HAVE_CLK=n. It all *looks* OK, but the clk API does its tests for clk==NULL in some very deep places.

drivers/rtc/rtc-snvs.c

Quoted 2 lines
drivers/rtc/rtc-snvs.c +0 -0

.

Quoted 5 lines

...

drivers/rtc/rtc-snvs.c +0 -0
@@ -288,10 +302,16 @@ static int snvs_rtc_probe(struct platform_device *pdev)
 	if (IS_ERR(data->rtc)) {
 		ret = PTR_ERR(data->rtc);

drivers/rtc/rtc-snvs.c static int snvs_rtc_probe(struct platform_device *pdev) · line 312

Quoted 10 lines
drivers/rtc/rtc-snvs.c +5 -1
 		dev_err(&pdev->dev, "failed to register rtc: %d\n", ret);
-		return ret;
+		goto error_rtc_device_register;
 	}
 
 	return 0;
+
+error_rtc_device_register:
+	if (data->clk)
+		clk_disable_unprepare(data->clk);

From my reading, there's no need to test data->clk here - clk_disable_unprepare() handles that.

It doesn't hurt to test it - a reasonable approach would be to look around at what other users of the clk API are doing, and do that.

drivers/rtc/rtc-snvs.c static int snvs_rtc_suspend(struct device *dev) · line 326

Quoted 10 lines
drivers/rtc/rtc-snvs.c +3 -0
+	return ret;
 }
 
 #ifdef CONFIG_PM_SLEEP

@@ -302,16 +322,26 @@ static int snvs_rtc_suspend(struct device *dev)
 	if (device_may_wakeup(dev))
 		enable_irq_wake(data->irq);
 
+	if (data->clk)
+		clk_disable_unprepare(data->clk);

Ditto.

Quoted 8 lines
drivers/rtc/rtc-snvs.c +1 -0
 	return 0;
 }
 
 static int snvs_rtc_resume(struct device *dev)
 {
 	struct snvs_rtc_data *data = dev_get_drvdata(dev);
+	int ret;
Quoted 9 lines

drivers/rtc/rtc-snvs.c static int snvs_rtc_suspend(struct device *dev) · line 343

Quoted 8 lines
drivers/rtc/rtc-snvs.c +5 -0
 	if (device_may_wakeup(dev))
 		disable_irq_wake(data->irq);
 
+	if (data->clk) {
+		ret = clk_prepare_enable(data->clk);
+		if (ret)
+			return ret;
+	}

Just discovered issue with suspend/resume I am testing right now: The alarm interrupt handler also reads registers which are part of SNVS and need clocks enabled. However, the resume function is called after IRQ's have been enabled, hence this leads to a abort:

[   90.755222] Unhandled fault: external abort on non-linefetch (0x1008)
at 0x908c604c
[   90.762892] Internal error: : 1008 [#1] ARM
[   90.767082] Modules linked in:
[   90.770174] CPU: 0 PID: 421 Comm: sh Not tainted
3.18.0-rc5-00135-g0689c67-dirty #1592
[   90.778100] task: 8e03e800 ti: 8cad8000 task.ti: 8cad8000
[   90.783530] PC is at snvs_rtc_irq_handler+0x14/0x74
[   90.788424] LR is at handle_irq_event_percpu+0x3c/0x144

It can be fixed, with something like this:

@@ -346,7 +347,10 @@ static int snvs_rtc_resume(struct device *dev)
}
#endif

-static SIMPLE_DEV_PM_OPS(snvs_rtc_pm_ops, snvs_rtc_suspend, snvs_rtc_resume);
+static const struct dev_pm_ops snvs_rtc_pm_ops = {
+ .suspend_noirq = snvs_rtc_suspend,
+ .resume_noirq = snvs_rtc_resume,
+};

 static const struct of_device_id snvs_dt_ids[] = {
        { .compatible = "fsl,sec-v4.0-mon-rtc-lp", },

Andrew, this patch is already merged, so it would need another fix for this, right?

--
Stefan

Quoted 5 lines

It could be omitted here also.

Quoted 3 lines
drivers/rtc/rtc-snvs.c +0 -0
 	return 0;
 }
 #endif
#8 lore raw

Re: [RESEND PATCHv2] drivers/rtc/rtc-snvs: Add clock support

Quoted 18 lines · On Fri, 05 Dec 2014 15:54:15 +0100 Stefan Agner <[email protected]> wrote:

It can be fixed, with something like this:

(quoted diff) +4 -1
@@ -346,7 +347,10 @@ static int snvs_rtc_resume(struct device *dev)
 }
 #endif
 
-static SIMPLE_DEV_PM_OPS(snvs_rtc_pm_ops, snvs_rtc_suspend,
 snvs_rtc_resume);
+static const struct dev_pm_ops snvs_rtc_pm_ops = {
+       .suspend_noirq = snvs_rtc_suspend,
+       .resume_noirq = snvs_rtc_resume,
+};
 
 static const struct of_device_id snvs_dt_ids[] = {

        { .compatible = "fsl,sec-v4.0-mon-rtc-lp", },
Quoted 2 lines

Andrew, this patch is already merged, so it would need another fix for this, right?

A replacement patch is OK. An incremental patch is OK too. I almost always turn the replacement into an incremental so that I and others can see what changed.