Re: [PATCH 2/3] Input: snvs_pwrkey - enable snvs clock as needed

[Horia Geanta <horia.geanta@nxp.com>]

On 1/30/2020 10:45 PM, André Draszik wrote:
> At the moment, enabling this driver without the SNVS RTC driver
> being active will hang the kernel as soon as the power button
> is pressed.
> 
> The reason is that in that case the SNVS isn't enabled, and
> any attempt to read the SNVS registers will simply hang forever.
> 
> Ensure the clock is enabled (during the interrupt handler) to
> make this driver work.
> 
> Also see commit 7f8993995410 ("drivers/rtc/rtc-snvs: add clock support")
> and commit edb190cb1734
> ("rtc: snvs: make sure clock is enabled for interrupt handle")
> for similar updates to the snvs rtc driver.
> 
> Signed-off-by: André Draszik <git@andred.net>
> Cc: Anson Huang <Anson.Huang@nxp.com>
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: "Horia Geantă" <horia.geanta@nxp.com>
> Cc: Aymen Sghaier <aymen.sghaier@nxp.com>
> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: Rob Herring <robh+dt@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: linux-crypto@vger.kernel.org
> Cc: devicetree@vger.kernel.org
> Cc: linux-input@vger.kernel.org
> ---
>  drivers/input/keyboard/snvs_pwrkey.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/input/keyboard/snvs_pwrkey.c b/drivers/input/keyboard/snvs_pwrkey.c
> index 2f5e3ab5ed63..c29711d8735c 100644
> --- a/drivers/input/keyboard/snvs_pwrkey.c
> +++ b/drivers/input/keyboard/snvs_pwrkey.c
> @@ -16,6 +16,7 @@
>  #include <linux/of_address.h>
>  #include <linux/platform_device.h>
>  #include <linux/pm_wakeirq.h>
> +#include <linux/clk.h>
>  #include <linux/mfd/syscon.h>
>  #include <linux/regmap.h>
>  
> @@ -38,6 +39,7 @@ struct pwrkey_drv_data {
>  	int wakeup;
>  	struct timer_list check_timer;
>  	struct input_dev *input;
> +	struct clk *clk;
>  	u8 minor_rev;
>  };
>  
> @@ -72,6 +74,9 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
>  	struct input_dev *input = pdata->input;
>  	u32 lp_status;
>  
> +	if (pdata->clk)
> +		clk_enable(pdata->clk);
> +
clk framework handles NULL pointers internally, the check is redundant.

>  	pm_wakeup_event(input->dev.parent, 0);
>  
>  	regmap_read(pdata->snvs, SNVS_LPSR_REG, &lp_status);
> @@ -96,6 +101,9 @@ static irqreturn_t imx_snvs_pwrkey_interrupt(int irq, void *dev_id)
>  	/* clear SPO status */
>  	regmap_write(pdata->snvs, SNVS_LPSR_REG, SNVS_LPSR_SPO);
>  
> +	if (pdata->clk)
> +		clk_disable(pdata->clk);
> +
>  	return IRQ_HANDLED;
>  }
>  
> @@ -140,6 +148,25 @@ static int imx_snvs_pwrkey_probe(struct platform_device *pdev)
>  	if (pdata->irq < 0)
>  		return -EINVAL;
>  
> +	pdata->clk = devm_clk_get(&pdev->dev, "snvs-pwrkey");
> +	if (IS_ERR(pdata->clk)) {
> +		pdata->clk = NULL;
Using devm_clk_get_optional() would simplify error handling.

> +	} else {
> +		error = clk_prepare_enable(pdata->clk);
> +		if (error) {
> +			dev_err(&pdev->dev,
> +				"Could not prepare or enable the snvs clock\n");
> +			return error;
> +		}
> +		error = devm_add_action_or_reset(&pdev->dev,
> +				(void(*)(void *))clk_disable_unprepare,
> +				pdata->clk);
> +		if (error) {
> +			dev_err(&pdev->dev, "failed to add reset action on 'snvs-pwrkey'");
> +			return error;
> +		}
> +	}
> +
>  	regmap_read(pdata->snvs, SNVS_HPVIDR1_REG, &vid);
>  	pdata->minor_rev = vid & 0xff;
>  
>