linux-kernel - Re: [PATCH v2 1/2] mailbox: pcc: Add support for platform notification handling

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Message-ID: <20230327113057.cc2ufila5z25mgic@bogus>
Date:   Mon, 27 Mar 2023 12:30:57 +0100
From:   Sudeep Holla <sudeep.holla@....com>
To:     Huisong Li <lihuisong@...wei.com>
Cc:     robbiek@...ghtlabs.com, linux-acpi@...r.kernel.org,
        Sudeep Holla <sudeep.holla@....com>,
        linux-kernel@...r.kernel.org, rafael@...nel.org,
        rafael.j.wysocki@...el.com, wanghuiqiang@...wei.com,
        zhangzekun11@...wei.com, wangxiongfeng2@...wei.com,
        tanxiaofei@...wei.com, guohanjun@...wei.com, xiexiuqi@...wei.com,
        wangkefeng.wang@...wei.com, huangdaode@...wei.com
Subject: Re: [PATCH v2 1/2] mailbox: pcc: Add support for platform
 notification handling

On Tue, Mar 14, 2023 at 07:11:34PM +0800, Huisong Li wrote:
> Currently, PCC driver doesn't support the processing of platform
> notification for type 4 PCC subspaces.
> 
> According to ACPI specification, if platform sends a notification
> to OSPM, it must clear the command complete bit and trigger platform
> interrupt. OSPM needs to check whether the command complete bit is
> cleared, clear platform interrupt, process command, and then set the
> command complete and ring doorbell to the Platform.
> 
> Let us stash the value of the pcc type and use the same while processing
> the interrupt of the channel. We also need to set the command complete
> bit and ring doorbell in the interrupt handler for the type 4 channel to
> complete the communication flow after processing the notification from
> the Platform.
> 
> Signed-off-by: Huisong Li <lihuisong@...wei.com>
> ---
>  drivers/mailbox/pcc.c | 50 +++++++++++++++++++++++++++++++++++--------
>  1 file changed, 41 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
> index 105d46c9801b..a0a87c480d8b 100644
> --- a/drivers/mailbox/pcc.c
> +++ b/drivers/mailbox/pcc.c
> @@ -91,6 +91,7 @@ struct pcc_chan_reg {
>   * @cmd_update: PCC register bundle for the command complete update register
>   * @error: PCC register bundle for the error status register
>   * @plat_irq: platform interrupt
> + * @type: PCC subspace type
>   */
>  struct pcc_chan_info {
>  	struct pcc_mbox_chan chan;
> @@ -100,12 +101,15 @@ struct pcc_chan_info {
>  	struct pcc_chan_reg cmd_update;
>  	struct pcc_chan_reg error;
>  	int plat_irq;
> +	u8 type;
>  };
>  
>  #define to_pcc_chan_info(c) container_of(c, struct pcc_chan_info, chan)
>  static struct pcc_chan_info *chan_info;
>  static int pcc_chan_count;
>  
> +static int pcc_send_data(struct mbox_chan *chan, void *data);
> +
>  /*
>   * PCC can be used with perf critical drivers such as CPPC
>   * So it makes sense to locally cache the virtual address and
> @@ -221,6 +225,34 @@ static int pcc_map_interrupt(u32 interrupt, u32 flags)
>  	return acpi_register_gsi(NULL, interrupt, trigger, polarity);
>  }
>  
> +static bool pcc_mbox_cmd_complete_check(struct pcc_chan_info *pchan)
> +{
> +	u64 val;
> +	int ret;
> +
> +	ret = pcc_chan_reg_read(&pchan->cmd_complete, &val);
> +	if (ret)
> +		return false;
> +
> +	if (!pchan->cmd_complete.gas)
> +		return true;
> +
> +	/*
> +	 * Judge if the channel respond the interrupt based on the value of
> +	 * command complete.
> +	 */
> +	val &= pchan->cmd_complete.status_mask;

[super nit] Would prefer an blank line here.

--
Regards,
Sudeep