linux-kernel - Re: [RFC PATCH v3 1/3] firmware: xilinx: Add reset API's

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Message-ID: <1536143389.4084.4.camel@pengutronix.de>
Date:   Wed, 05 Sep 2018 12:29:49 +0200
From:   Philipp Zabel <p.zabel@...gutronix.de>
To:     Nava kishore Manne <nava.manne@...inx.com>, robh+dt@...nel.org,
        mark.rutland@....com, michal.simek@...inx.com, rajanv@...inx.com,
        jollys@...inx.com, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v3 1/3] firmware: xilinx: Add reset API's

Hi,

On Wed, 2018-09-05 at 12:39 +0530, Nava kishore Manne wrote:
> This Patch Adds reset API's to support release, assert
> and status functionalities by using firmware interface.
> 
> Signed-off-by: Nava kishore Manne <nava.manne@...inx.com>
> ---
> Changes for v3:
> 		-None.
> Changes for v2:
> 		-New Patch.
> 
>  drivers/firmware/xilinx/zynqmp.c     |  40 +++++++++++
>  include/linux/firmware/xlnx-zynqmp.h | 136 +++++++++++++++++++++++++++++++++++
>  2 files changed, 176 insertions(+)
> 
> diff --git a/drivers/firmware/xilinx/zynqmp.c b/drivers/firmware/xilinx/zynqmp.c
> index 7ccedf0..639c72f 100644
> --- a/drivers/firmware/xilinx/zynqmp.c
> +++ b/drivers/firmware/xilinx/zynqmp.c
> @@ -447,6 +447,44 @@ static int zynqmp_pm_clock_getparent(u32 clock_id, u32 *parent_id)
>  	return ret;
>  }
>  
> +/**
> + * zynqmp_pm_reset_assert - Request setting of reset (1 - assert, 0 - release)
> + * @reset:		Reset to be configured
> + * @assert_flag:	Flag stating should reset be asserted (1) or
> + *			released (0)
> + *
> + * Return: Returns status, either success or error+reason
> + */
> +static int zynqmp_pm_reset_assert(const enum zynqmp_pm_reset reset,
> +				  const enum zynqmp_pm_reset_action assert_flag)
> +{
> +	return zynqmp_pm_invoke_fn(PM_RESET_ASSERT, reset, assert_flag,
> +				   0, 0, NULL);
> +}
> +
> +/**
> + * zynqmp_pm_reset_get_status - Get status of the reset
> + * @reset:      Reset whose status should be returned
> + * @status:     Returned status
> + *
> + * Return: Returns status, either success or error+reason
> + */
> +static int zynqmp_pm_reset_get_status(const enum zynqmp_pm_reset reset,
> +				      u32 *status)
> +{
> +	u32 ret_payload[PAYLOAD_ARG_CNT];
> +	int ret;
> +
> +	if (!status)
> +		return -EINVAL;
> +
> +	ret = zynqmp_pm_invoke_fn(PM_RESET_GET_STATUS, reset, 0,
> +				  0, 0, ret_payload);
> +	*status = ret_payload[1];

It doesn't really matter here, but in general I'd skip writing output
arguments in case of error.
For all I know, the result returned in ret_payload could be undefined.

regards
Philipp