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Commit 7fdec110 authored by Romain Izard's avatar Romain Izard Committed by Lee Jones
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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: default avatarRomain Izard <romain.izard.pro@gmail.com>
Acked-by: default avatarAlexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: default avatarNicolas Ferre <nicolas.ferre@microchip.com>
Tested-by: default avatarNicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: default avatarLee Jones <lee.jones@linaro.org>
parent 63fb9cb5

drivers/mfd/atmel-flexcom.c

+48 −15
Original line number Diff line number Diff line
@@ -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,

	},

};