linux-kernel - Re: [PATCH v6] atmel_flexcom: Support resuming after a chip reset

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Message-ID: <5aff8591-f7d9-7f6d-bf3b-063014ce4bd5@microchip.com>
Date:   Tue, 19 Dec 2017 09:52:50 +0100
From:   Nicolas Ferre <nicolas.ferre@...rochip.com>
To:     Lee Jones <lee.jones@...aro.org>
CC:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Romain Izard <romain.izard.pro@...il.com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v6] atmel_flexcom: Support resuming after a chip reset

On 18/12/2017 at 21:19, Alexandre Belloni wrote:
> On 12/12/2017 at 17:21:19 +0100, Romain Izard wrote:
>> 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 <romain.izard.pro@...il.com>
> 
> Seems good to me
> 
> Acked-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

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

Acked-by: Nicolas Ferre <nicolas.ferre@...rochip.com>
Tested-by: Nicolas Ferre <nicolas.ferre@...rochip.com>

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?

Best regards,
  Nicolas


>> ---
>> 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(-)
>>
>> diff --git a/drivers/mfd/atmel-flexcom.c b/drivers/mfd/atmel-flexcom.c
>> index 064bde9cff5a..f684a93a3340 100644
>> --- a/drivers/mfd/atmel-flexcom.c
>> +++ b/drivers/mfd/atmel-flexcom.c
>> @@ -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,
>>  	},
>>  };
>> -- 
>> 2.14.1
>>
> 


-- 
Nicolas Ferre