atmel_flexcom: Support resuming after a chip reset

The controller used by a flexcom module is configured at boot, and left alone after this. In the suspend mode called "backup with self-refresh" available on SAMA5D2, the chip will resume with most of its registers reset. In this case, we need to restore the state of the flexcom driver on resume.

Signed-off-by Romain Izard <[email protected]>

---
Changes in v5:
* extract from the patch series, and send as a standalone patch

Changes in v6:
* Reword the patch title and description
* Rename the internal structure to ddata

 drivers/mfd/atmel-flexcom.c | 63 ++++++++++++++++++++++++++++++++++-----------
 1 file changed, 48 insertions(+), 15 deletions(-)

drivers/mfd/atmel-flexcom.c +48 -15

index 064bde9cff5a..f684a93a3340 100644
@@ -39,34 +39,43 @@
 #define FLEX_MR_OPMODE(opmode)	(((opmode) << FLEX_MR_OPMODE_OFFSET) &	\
 				 FLEX_MR_OPMODE_MASK)
 
+struct atmel_flexcom {
+	void __iomem *base;
+	u32 opmode;
+	struct clk *clk;
+};
 
 static int atmel_flexcom_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
-	struct clk *clk;
 	struct resource *res;
-	void __iomem *base;
-	u32 opmode;
+	struct atmel_flexcom *ddata;
 	int err;
 
-	err = of_property_read_u32(np, "atmel,flexcom-mode", &opmode);
+	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, ddata);
+
+	err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
 	if (err)
 		return err;
 
-	if (opmode < ATMEL_FLEXCOM_MODE_USART ||
-	    opmode > ATMEL_FLEXCOM_MODE_TWI)
+	if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
+	    ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
 		return -EINVAL;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	base = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(base))
-		return PTR_ERR(base);
+	ddata->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ddata->base))
+		return PTR_ERR(ddata->base);
 
-	clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(clk))
-		return PTR_ERR(clk);
+	ddata->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(ddata->clk))
+		return PTR_ERR(ddata->clk);
 
-	err = clk_prepare_enable(clk);
+	err = clk_prepare_enable(ddata->clk);
 	if (err)
 		return err;
 

@@ -76,9 +85,9 @@ static int atmel_flexcom_probe(struct platform_device *pdev)
 	 * inaccessible and are read as zero. Also the external I/O lines of the
 	 * Flexcom are muxed to reach the selected device.
 	 */
-	writel(FLEX_MR_OPMODE(opmode), base + FLEX_MR);
+	writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
 
-	clk_disable_unprepare(clk);
+	clk_disable_unprepare(ddata->clk);
 
 	return devm_of_platform_populate(&pdev->dev);
 }

@@ -89,10 +98,34 @@ static const struct of_device_id atmel_flexcom_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
 
+#ifdef CONFIG_PM_SLEEP
+static int atmel_flexcom_resume(struct device *dev)
+{
+	struct atmel_flexcom *ddata = dev_get_drvdata(dev);
+	int err;
+	u32 val;
+
+	err = clk_prepare_enable(ddata->clk);
+	if (err)
+		return err;
+
+	val = FLEX_MR_OPMODE(ddata->opmode),
+	writel(val, ddata->base + FLEX_MR);
+
+	clk_disable_unprepare(ddata->clk);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
+			 atmel_flexcom_resume);
+
 static struct platform_driver atmel_flexcom_driver = {
 	.probe	= atmel_flexcom_probe,
 	.driver	= {
 		.name		= "atmel_flexcom",
+		.pm		= &atmel_flexcom_pm_ops,
 		.of_match_table	= atmel_flexcom_of_match,
 	},
 };

Signature · 1 line

2.14.1

Quoted 6 lines · Romain Izard

The controller used by a flexcom module is configured at boot, and left alone after this. In the suspend mode called "backup with self-refresh" available on SAMA5D2, the chip will resume with most of its registers reset. In this case, we need to restore the state of the flexcom driver on resume.

Quoted 1 line

Signed-off-by Romain Izard <[email protected]>

Seems good to me

Acked-by Alexandre Belloni <[email protected]>

Quoted 122 lines

---
Changes in v5:
* extract from the patch series, and send as a standalone patch

Changes in v6:
* Reword the patch title and description
* Rename the internal structure to ddata

 drivers/mfd/atmel-flexcom.c | 63 ++++++++++++++++++++++++++++++++++-----------
 1 file changed, 48 insertions(+), 15 deletions(-)

drivers/mfd/atmel-flexcom.c +48 -15

index 064bde9cff5a..f684a93a3340 100644
@@ -39,34 +39,43 @@
 #define FLEX_MR_OPMODE(opmode)	(((opmode) << FLEX_MR_OPMODE_OFFSET) &	\
 				 FLEX_MR_OPMODE_MASK)
 
+struct atmel_flexcom {
+	void __iomem *base;
+	u32 opmode;
+	struct clk *clk;
+};
 
 static int atmel_flexcom_probe(struct platform_device *pdev)
 {
 	struct device_node *np = pdev->dev.of_node;
-	struct clk *clk;
 	struct resource *res;
-	void __iomem *base;
-	u32 opmode;
+	struct atmel_flexcom *ddata;
 	int err;
 
-	err = of_property_read_u32(np, "atmel,flexcom-mode", &opmode);
+	ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
+	if (!ddata)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, ddata);
+
+	err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
 	if (err)
 		return err;
 
-	if (opmode < ATMEL_FLEXCOM_MODE_USART ||
-	    opmode > ATMEL_FLEXCOM_MODE_TWI)
+	if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
+	    ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
 		return -EINVAL;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	base = devm_ioremap_resource(&pdev->dev, res);
-	if (IS_ERR(base))
-		return PTR_ERR(base);
+	ddata->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(ddata->base))
+		return PTR_ERR(ddata->base);
 
-	clk = devm_clk_get(&pdev->dev, NULL);
-	if (IS_ERR(clk))
-		return PTR_ERR(clk);
+	ddata->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(ddata->clk))
+		return PTR_ERR(ddata->clk);
 
-	err = clk_prepare_enable(clk);
+	err = clk_prepare_enable(ddata->clk);
 	if (err)
 		return err;
 

@@ -76,9 +85,9 @@ static int atmel_flexcom_probe(struct platform_device *pdev)
 	 * inaccessible and are read as zero. Also the external I/O lines of the
 	 * Flexcom are muxed to reach the selected device.
 	 */
-	writel(FLEX_MR_OPMODE(opmode), base + FLEX_MR);
+	writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
 
-	clk_disable_unprepare(clk);
+	clk_disable_unprepare(ddata->clk);
 
 	return devm_of_platform_populate(&pdev->dev);
 }

@@ -89,10 +98,34 @@ static const struct of_device_id atmel_flexcom_of_match[] = {
 };
 MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
 
+#ifdef CONFIG_PM_SLEEP
+static int atmel_flexcom_resume(struct device *dev)
+{
+	struct atmel_flexcom *ddata = dev_get_drvdata(dev);
+	int err;
+	u32 val;
+
+	err = clk_prepare_enable(ddata->clk);
+	if (err)
+		return err;
+
+	val = FLEX_MR_OPMODE(ddata->opmode),
+	writel(val, ddata->base + FLEX_MR);
+
+	clk_disable_unprepare(ddata->clk);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
+			 atmel_flexcom_resume);
+
 static struct platform_driver atmel_flexcom_driver = {
 	.probe	= atmel_flexcom_probe,
 	.driver	= {
 		.name		= "atmel_flexcom",
+		.pm		= &atmel_flexcom_pm_ops,
 		.of_match_table	= atmel_flexcom_of_match,
 	},
 };

Signature · 1 line

2.14.1

Quoted 7 lines · Alexandre Belloni

Quoted 6 lines · Romain Izard

The controller used by a flexcom module is configured at boot, and left alone after this. In the suspend mode called "backup with self-refresh" available on SAMA5D2, the chip will resume with most of its registers reset. In this case, we need to restore the state of the flexcom driver on resume.

Quoted 5 lines

Quoted 1 line

Signed-off-by Romain Izard <[email protected]>

Seems good to me

Acked-by Alexandre Belloni <[email protected]>

Thanks Romain, of course I can add the tags that I gave you already:

Acked-by Nicolas Ferre <[email protected]>

Tested-by Nicolas Ferre <[email protected]>

Lee,
It seems that you already gave your tag for the v5 of this patch. The wording is even better with this patch. So, can you take this patch in your tree?

The controller used by a flexcom module is configured at boot, and left alone after this. In the suspend mode called "backup with self-refresh" available on SAMA5D2, the chip will resume with most of its registers reset. In this case, we need to restore the state of the flexcom driver on resume.

Signed-off-by Romain Izard <[email protected]>

---
Changes in v5:
* extract from the patch series, and send as a standalone patch

Changes in v6:
* Reword the patch title and description
* Rename the internal structure to ddata

 drivers/mfd/atmel-flexcom.c | 63 ++++++++++++++++++++++++++++++++++-----------
 1 file changed, 48 insertions(+), 15 deletions(-)