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SubjectRe: [[PATCHv2] 3/3] drivers/rtc/rtc-snvs: Add clock support
On Wednesday 12 November 2014 02:57 AM, Stefan Agner wrote:
> On 2014-11-07 14:04, Sanchayan Maity wrote:
>> This patch adds clock enable and disable support for
>> the SNVS peripheral, which is required for using the
>> RTC within the SNVS block.
>
> What happens if the device tree node is there while this patch is not
> applied? I guess the driver would load, but since the clocks of the
> peripheral are not enabled the first register access would lead to bus
> error or similar. If this is the case, this would break bisectability.
> You should move the device tree patch to the end.
>

If the DT node was present with this patch not applied, the driver would
still crash with a bus error, since the clocks for SNVS are not explicitly
enabled anywhere else. I had not thought about any problems which might
occur later with git bisect. Will move this to the end with v3.

Thanks.

Regards,
Sanchayan.

> Other than that
> Acked-by: Stefan Agner <stefan@agner.ch>
>
> --
> Stefan
>
>>
>> Signed-off-by: Sanchayan Maity <maitysanchayan@gmail.com>
>> ---
>> drivers/rtc/rtc-snvs.c | 34 ++++++++++++++++++++++++++++++++--
>> 1 file changed, 32 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/rtc/rtc-snvs.c b/drivers/rtc/rtc-snvs.c
>> index fa384fe..d4a6512 100644
>> --- a/drivers/rtc/rtc-snvs.c
>> +++ b/drivers/rtc/rtc-snvs.c
>> @@ -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
>


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