[PATCH 0/7] hwrnd: atmel - add runtime pm support

[PATCH 0/7] hwrnd: atmel - add runtime pm support

[Claudiu Beznea]

Hi,

This series adds runtime PM support for atmel-rng driver. Along with
this some cleanup and fixes patches were added to the series.

Thank you,
Claudiu Beznea

Claudiu Beznea (7):
  hwrng: atmel - add wait for ready support on read
  hwrnd: atmel - disable trng on failure path
  hwrnd: atmel - rename enable/disable functions to init/cleanup
  hwrng: atmel - move set of TRNG_HALFR in atmel_trng_init()
  hwrnd: atmel - use __maybe_unused and pm_ptr() for pm ops
  hwrnd: atmel - add runtime pm support
  hwrnd: atmel - remove extra line

 drivers/char/hw_random/atmel-rng.c | 148 ++++++++++++++++++-----------
 1 file changed, 91 insertions(+), 57 deletions(-)

-- 
2.32.0

[PATCH 1/7] hwrng: atmel - add wait for ready support on read

[Claudiu Beznea]

Add wait for ready support on read.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 drivers/char/hw_random/atmel-rng.c | 43 +++++++++++++++++++++---------
 1 file changed, 30 insertions(+), 13 deletions(-)

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index ecb71c4317a5..1a4874668c04 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -13,6 +13,7 @@
 #include <linux/err.h>
 #include <linux/clk.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/hw_random.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
@@ -20,6 +21,7 @@
 #define TRNG_CR		0x00
 #define TRNG_MR		0x04
 #define TRNG_ISR	0x1c
+#define TRNG_ISR_DATRDY	BIT(0)
 #define TRNG_ODATA	0x50
 
 #define TRNG_KEY	0x524e4700 /* RNG */
@@ -36,25 +38,40 @@ struct atmel_trng {
 	struct hwrng rng;
 };
 
+static bool atmel_trng_wait_ready(struct atmel_trng *trng, bool wait)
+{
+	int ready;
+
+	ready = readl(trng->base + TRNG_ISR) & TRNG_ISR_DATRDY;
+	if (!ready && wait)
+		readl_poll_timeout(trng->base + TRNG_ISR, ready,
+				   ready & TRNG_ISR_DATRDY, 1000, 20000);
+
+	return !!ready;
+}
+
 static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
 			   bool wait)
 {
 	struct atmel_trng *trng = container_of(rng, struct atmel_trng, rng);
 	u32 *data = buf;
+	int ret;
+
+	ret = atmel_trng_wait_ready(trng, wait);
+	if (!ret)
+		goto out;
 
-	/* data ready? */
-	if (readl(trng->base + TRNG_ISR) & 1) {
-		*data = readl(trng->base + TRNG_ODATA);
-		/*
-		  ensure data ready is only set again AFTER the next data
-		  word is ready in case it got set between checking ISR
-		  and reading ODATA, so we don't risk re-reading the
-		  same word
-		*/
-		readl(trng->base + TRNG_ISR);
-		return 4;
-	} else
-		return 0;
+	*data = readl(trng->base + TRNG_ODATA);
+	/*
+	 * ensure data ready is only set again AFTER the next data word is ready
+	 * in case it got set between checking ISR and reading ODATA, so we
+	 * don't risk re-reading the same word
+	 */
+	readl(trng->base + TRNG_ISR);
+	ret = 4;
+
+out:
+	return ret;
 }
 
 static void atmel_trng_enable(struct atmel_trng *trng)
-- 
2.32.0

[PATCH 2/7] hwrnd: atmel - disable trng on failure path

[Claudiu Beznea]

Call atmel_trng_disable() on failure path of probe.

Fixes: a1fa98d8116f ("hwrng: atmel - disable TRNG during suspend")
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 drivers/char/hw_random/atmel-rng.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index 1a4874668c04..b7ef951927fb 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -131,6 +131,7 @@ static int atmel_trng_probe(struct platform_device *pdev)
 
 err_register:
 	clk_disable_unprepare(trng->clk);
+	atmel_trng_disable(trng);
 	return ret;
 }
 
-- 
2.32.0

[PATCH 3/7] hwrnd: atmel - rename enable/disable functions to init/cleanup

[Claudiu Beznea]

s/atmel_trng_disable/atmel_trng_cleanup/g and
s/atmel_trng_enable/atmel_trng_init/g to cope with
struct hwrng::{init, cleanup} members.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 drivers/char/hw_random/atmel-rng.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index b7ef951927fb..17f02049c112 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -74,12 +74,12 @@ static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
 	return ret;
 }
 
-static void atmel_trng_enable(struct atmel_trng *trng)
+static void atmel_trng_init(struct atmel_trng *trng)
 {
 	writel(TRNG_KEY | 1, trng->base + TRNG_CR);
 }
 
-static void atmel_trng_disable(struct atmel_trng *trng)
+static void atmel_trng_cleanup(struct atmel_trng *trng)
 {
 	writel(TRNG_KEY, trng->base + TRNG_CR);
 }
@@ -117,7 +117,7 @@ static int atmel_trng_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
-	atmel_trng_enable(trng);
+	atmel_trng_init(trng);
 	trng->rng.name = pdev->name;
 	trng->rng.read = atmel_trng_read;
 
@@ -131,7 +131,7 @@ static int atmel_trng_probe(struct platform_device *pdev)
 
 err_register:
 	clk_disable_unprepare(trng->clk);
-	atmel_trng_disable(trng);
+	atmel_trng_cleanup(trng);
 	return ret;
 }
 
@@ -140,7 +140,7 @@ static int atmel_trng_remove(struct platform_device *pdev)
 	struct atmel_trng *trng = platform_get_drvdata(pdev);
 
 
-	atmel_trng_disable(trng);
+	atmel_trng_cleanup(trng);
 	clk_disable_unprepare(trng->clk);
 
 	return 0;
@@ -151,7 +151,7 @@ static int atmel_trng_suspend(struct device *dev)
 {
 	struct atmel_trng *trng = dev_get_drvdata(dev);
 
-	atmel_trng_disable(trng);
+	atmel_trng_cleanup(trng);
 	clk_disable_unprepare(trng->clk);
 
 	return 0;
@@ -166,7 +166,7 @@ static int atmel_trng_resume(struct device *dev)
 	if (ret)
 		return ret;
 
-	atmel_trng_enable(trng);
+	atmel_trng_init(trng);
 
 	return 0;
 }
-- 
2.32.0

[PATCH 4/7] hwrng: atmel - move set of TRNG_HALFR in atmel_trng_init()

[Claudiu Beznea]

Move set of TRNG_HALFR in atmel_trng_init() as this function is
also called on resume path. In case of SAMA7G5 (where backup and
self-refresh PM mode is available) most of the SoC parts are
powered of (including TRNG) when entering suspend. In that case
on resuming path TRNG_HALFR should also be re-configured.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 drivers/char/hw_random/atmel-rng.c | 49 +++++++++++++++---------------
 1 file changed, 25 insertions(+), 24 deletions(-)

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index 17f02049c112..ef49dbe681cf 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -36,6 +36,7 @@ struct atmel_trng {
 	struct clk *clk;
 	void __iomem *base;
 	struct hwrng rng;
+	bool has_half_rate;
 };
 
 static bool atmel_trng_wait_ready(struct atmel_trng *trng, bool wait)
@@ -74,14 +75,32 @@ static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
 	return ret;
 }
 
-static void atmel_trng_init(struct atmel_trng *trng)
+static int atmel_trng_init(struct atmel_trng *trng)
 {
+	unsigned long rate;
+	int ret;
+
+	ret = clk_prepare_enable(trng->clk);
+	if (ret)
+		return ret;
+
+	if (trng->has_half_rate) {
+		rate = clk_get_rate(trng->clk);
+
+		/* if peripheral clk is above 100MHz, set HALFR */
+		if (rate > 100000000)
+			writel(TRNG_HALFR, trng->base + TRNG_MR);
+	}
+
 	writel(TRNG_KEY | 1, trng->base + TRNG_CR);
+
+	return 0;
 }
 
 static void atmel_trng_cleanup(struct atmel_trng *trng)
 {
 	writel(TRNG_KEY, trng->base + TRNG_CR);
+	clk_disable_unprepare(trng->clk);
 }
 
 static int atmel_trng_probe(struct platform_device *pdev)
@@ -105,22 +124,14 @@ static int atmel_trng_probe(struct platform_device *pdev)
 	if (!data)
 		return -ENODEV;
 
-	if (data->has_half_rate) {
-		unsigned long rate = clk_get_rate(trng->clk);
-
-		/* if peripheral clk is above 100MHz, set HALFR */
-		if (rate > 100000000)
-			writel(TRNG_HALFR, trng->base + TRNG_MR);
-	}
+	trng->has_half_rate = data->has_half_rate;
+	trng->rng.name = pdev->name;
+	trng->rng.read = atmel_trng_read;
 
-	ret = clk_prepare_enable(trng->clk);
+	ret = atmel_trng_init(trng);
 	if (ret)
 		return ret;
 
-	atmel_trng_init(trng);
-	trng->rng.name = pdev->name;
-	trng->rng.read = atmel_trng_read;
-
 	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
 	if (ret)
 		goto err_register;
@@ -130,7 +141,6 @@ static int atmel_trng_probe(struct platform_device *pdev)
 	return 0;
 
 err_register:
-	clk_disable_unprepare(trng->clk);
 	atmel_trng_cleanup(trng);
 	return ret;
 }
@@ -141,7 +151,6 @@ static int atmel_trng_remove(struct platform_device *pdev)
 
 
 	atmel_trng_cleanup(trng);
-	clk_disable_unprepare(trng->clk);
 
 	return 0;
 }
@@ -152,7 +161,6 @@ static int atmel_trng_suspend(struct device *dev)
 	struct atmel_trng *trng = dev_get_drvdata(dev);
 
 	atmel_trng_cleanup(trng);
-	clk_disable_unprepare(trng->clk);
 
 	return 0;
 }
@@ -160,15 +168,8 @@ static int atmel_trng_suspend(struct device *dev)
 static int atmel_trng_resume(struct device *dev)
 {
 	struct atmel_trng *trng = dev_get_drvdata(dev);
-	int ret;
 
-	ret = clk_prepare_enable(trng->clk);
-	if (ret)
-		return ret;
-
-	atmel_trng_init(trng);
-
-	return 0;
+	return atmel_trng_init(trng);
 }
 
 static const struct dev_pm_ops atmel_trng_pm_ops = {
-- 
2.32.0

[PATCH 5/7] hwrnd: atmel - use __maybe_unused and pm_ptr() for pm ops

[Claudiu Beznea]

Use __maybe_unused and pm_ptr() for pm ops.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 drivers/char/hw_random/atmel-rng.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index ef49dbe681cf..0fff74808472 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -155,8 +155,7 @@ static int atmel_trng_remove(struct platform_device *pdev)
 	return 0;
 }
 
-#ifdef CONFIG_PM
-static int atmel_trng_suspend(struct device *dev)
+static int __maybe_unused atmel_trng_suspend(struct device *dev)
 {
 	struct atmel_trng *trng = dev_get_drvdata(dev);
 
@@ -165,18 +164,17 @@ static int atmel_trng_suspend(struct device *dev)
 	return 0;
 }
 
-static int atmel_trng_resume(struct device *dev)
+static int __maybe_unused atmel_trng_resume(struct device *dev)
 {
 	struct atmel_trng *trng = dev_get_drvdata(dev);
 
 	return atmel_trng_init(trng);
 }
 
-static const struct dev_pm_ops atmel_trng_pm_ops = {
+static const struct dev_pm_ops __maybe_unused atmel_trng_pm_ops = {
 	.suspend	= atmel_trng_suspend,
 	.resume		= atmel_trng_resume,
 };
-#endif /* CONFIG_PM */
 
 static const struct atmel_trng_data at91sam9g45_config = {
 	.has_half_rate = false,
@@ -204,9 +202,7 @@ static struct platform_driver atmel_trng_driver = {
 	.remove		= atmel_trng_remove,
 	.driver		= {
 		.name	= "atmel-trng",
-#ifdef CONFIG_PM
-		.pm	= &atmel_trng_pm_ops,
-#endif /* CONFIG_PM */
+		.pm	= pm_ptr(&atmel_trng_pm_ops),
 		.of_match_table = atmel_trng_dt_ids,
 	},
 };
-- 
2.32.0

[PATCH 6/7] hwrnd: atmel - add runtime pm support

[Claudiu Beznea]

Add runtime PM support.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 drivers/char/hw_random/atmel-rng.c | 44 ++++++++++++++++++++++--------
 1 file changed, 32 insertions(+), 12 deletions(-)

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index 0fff74808472..b662d44a09a6 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -17,6 +17,7 @@
 #include <linux/hw_random.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
 
 #define TRNG_CR		0x00
 #define TRNG_MR		0x04
@@ -58,6 +59,12 @@ static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
 	u32 *data = buf;
 	int ret;
 
+	ret = pm_runtime_get_sync((struct device *)trng->rng.priv);
+	if (ret < 0) {
+		pm_runtime_put_sync((struct device *)trng->rng.priv);
+		return ret;
+	}
+
 	ret = atmel_trng_wait_ready(trng, wait);
 	if (!ret)
 		goto out;
@@ -72,6 +79,8 @@ static int atmel_trng_read(struct hwrng *rng, void *buf, size_t max,
 	ret = 4;
 
 out:
+	pm_runtime_mark_last_busy((struct device *)trng->rng.priv);
+	pm_runtime_put_sync_autosuspend((struct device *)trng->rng.priv);
 	return ret;
 }
 
@@ -127,21 +136,28 @@ static int atmel_trng_probe(struct platform_device *pdev)
 	trng->has_half_rate = data->has_half_rate;
 	trng->rng.name = pdev->name;
 	trng->rng.read = atmel_trng_read;
+	trng->rng.priv = (unsigned long)&pdev->dev;
+	platform_set_drvdata(pdev, trng);
 
+#ifndef CONFIG_PM
 	ret = atmel_trng_init(trng);
 	if (ret)
 		return ret;
+#endif
 
-	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
-	if (ret)
-		goto err_register;
-
-	platform_set_drvdata(pdev, trng);
+	pm_runtime_set_autosuspend_delay(&pdev->dev, 100);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
 
-	return 0;
+	ret = devm_hwrng_register(&pdev->dev, &trng->rng);
+	if (ret) {
+		pm_runtime_disable(&pdev->dev);
+		pm_runtime_set_suspended(&pdev->dev);
+#ifndef CONFIG_PM
+		atmel_trng_cleanup(trng);
+#endif
+	}
 
-err_register:
-	atmel_trng_cleanup(trng);
 	return ret;
 }
 
@@ -151,11 +167,13 @@ static int atmel_trng_remove(struct platform_device *pdev)
 
 
 	atmel_trng_cleanup(trng);
+	pm_runtime_disable(&pdev->dev);
+	pm_runtime_set_suspended(&pdev->dev);
 
 	return 0;
 }
 
-static int __maybe_unused atmel_trng_suspend(struct device *dev)
+static int __maybe_unused atmel_trng_runtime_suspend(struct device *dev)
 {
 	struct atmel_trng *trng = dev_get_drvdata(dev);
 
@@ -164,7 +182,7 @@ static int __maybe_unused atmel_trng_suspend(struct device *dev)
 	return 0;
 }
 
-static int __maybe_unused atmel_trng_resume(struct device *dev)
+static int __maybe_unused atmel_trng_runtime_resume(struct device *dev)
 {
 	struct atmel_trng *trng = dev_get_drvdata(dev);
 
@@ -172,8 +190,10 @@ static int __maybe_unused atmel_trng_resume(struct device *dev)
 }
 
 static const struct dev_pm_ops __maybe_unused atmel_trng_pm_ops = {
-	.suspend	= atmel_trng_suspend,
-	.resume		= atmel_trng_resume,
+	SET_RUNTIME_PM_OPS(atmel_trng_runtime_suspend,
+			   atmel_trng_runtime_resume, NULL)
+	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
+				pm_runtime_force_resume)
 };
 
 static const struct atmel_trng_data at91sam9g45_config = {
-- 
2.32.0

[PATCH 7/7] hwrnd: atmel - remove extra line

[Claudiu Beznea]

Remove extra line.

Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
---
 drivers/char/hw_random/atmel-rng.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/char/hw_random/atmel-rng.c b/drivers/char/hw_random/atmel-rng.c
index b662d44a09a6..b8effe77d80f 100644
--- a/drivers/char/hw_random/atmel-rng.c
+++ b/drivers/char/hw_random/atmel-rng.c
@@ -165,7 +165,6 @@ static int atmel_trng_remove(struct platform_device *pdev)
 {
 	struct atmel_trng *trng = platform_get_drvdata(pdev);
 
-
 	atmel_trng_cleanup(trng);
 	pm_runtime_disable(&pdev->dev);
 	pm_runtime_set_suspended(&pdev->dev);
-- 
2.32.0

Re: [PATCH 0/7] hwrnd: atmel - add runtime pm support

[Alexandre Belloni]

On 18/02/2022 12:17:05+0200, Claudiu Beznea wrote:
> Hi,
> 
> This series adds runtime PM support for atmel-rng driver. Along with
> this some cleanup and fixes patches were added to the series.
> 
> Thank you,
> Claudiu Beznea
> 
> Claudiu Beznea (7):
>   hwrng: atmel - add wait for ready support on read
>   hwrnd: atmel - disable trng on failure path
>   hwrnd: atmel - rename enable/disable functions to init/cleanup
>   hwrng: atmel - move set of TRNG_HALFR in atmel_trng_init()
>   hwrnd: atmel - use __maybe_unused and pm_ptr() for pm ops
>   hwrnd: atmel - add runtime pm support
>   hwrnd: atmel - remove extra line
>

I don't mind too much but you are mixing hwrng and hwrnd ;)
 
>  drivers/char/hw_random/atmel-rng.c | 148 ++++++++++++++++++-----------
>  1 file changed, 91 insertions(+), 57 deletions(-)
> 
> -- 
> 2.32.0
> 

-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com