linux-kernel - Re: [PATCH 2/2] mailbox: imx: support channel type tx doorbell v2

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Message-ID: <CAEnQRZBbdrwX3mq=1RVHwzPAUtWjrKmz3y4ezOann6yZUwZAYA@mail.gmail.com>
Date:   Mon, 18 Sep 2023 13:36:25 +0300
From:   Daniel Baluta <daniel.baluta@...il.com>
To:     "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc:     Jassi Brar <jassisinghbrar@...il.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Dong Aisheng <aisheng.dong@....com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        devicetree@...r.kernel.org, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH 2/2] mailbox: imx: support channel type tx doorbell v2

On Sun, Sep 17, 2023 at 5:45 PM Peng Fan (OSS) <peng.fan@....nxp.com> wrote:
>
> From: Peng Fan <peng.fan@....com>
>
> The Message Unit(MU) General Purpose Control registers are used for
> TX doorbell, but there is no hardware ACK support.
>
> The current TX doorbell channel is using tasklet to emulate hardware
> ACK support to kick the TX tick from controller driver side.
>
> The new added TX doorbell channel V2 not using tasklet to emulate the
> hardware ACK support. The behavior for the channel is just writing the
> GCR register, and no else. This will be used for SCMI mailbox.
>
> Signed-off-by: Peng Fan <peng.fan@....com>
> ---
>  drivers/mailbox/imx-mailbox.c | 32 +++++++++++++++++++++++++++++---
>  1 file changed, 29 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mailbox/imx-mailbox.c b/drivers/mailbox/imx-mailbox.c
> index 3ef4dd8adf5d..0af739ab571c 100644
> --- a/drivers/mailbox/imx-mailbox.c
> +++ b/drivers/mailbox/imx-mailbox.c
> @@ -20,7 +20,9 @@
>  #include <linux/suspend.h>
>  #include <linux/slab.h>
>
> -#define IMX_MU_CHANS           17
> +#include "mailbox.h"
> +
> +#define IMX_MU_CHANS           24
>  /* TX0/RX0/RXDB[0-3] */
>  #define IMX_MU_SCU_CHANS       6
>  /* TX0/RX0 */
> @@ -39,6 +41,7 @@ enum imx_mu_chan_type {
>         IMX_MU_TYPE_TXDB        = 2, /* Tx doorbell */
>         IMX_MU_TYPE_RXDB        = 3, /* Rx doorbell */
>         IMX_MU_TYPE_RST         = 4, /* Reset */
> +       IMX_MU_TYPE_TXDB_V2     = 5, /* Tx doorbell with S/W ACK */
>  };
>
>  enum imx_mu_xcr {
> @@ -226,6 +229,9 @@ static int imx_mu_generic_tx(struct imx_mu_priv *priv,
>                 imx_mu_xcr_rmw(priv, IMX_MU_GCR, IMX_MU_xCR_GIRn(priv->dcfg->type, cp->idx), 0);
>                 tasklet_schedule(&cp->txdb_tasklet);
>                 break;
> +       case IMX_MU_TYPE_TXDB_V2:
> +               imx_mu_xcr_rmw(priv, IMX_MU_GCR, IMX_MU_xCR_GIRn(priv->dcfg->type, cp->idx), 0);
> +               break;
>         default:
>                 dev_warn_ratelimited(priv->dev, "Send data on wrong channel type: %d\n", cp->type);
>                 return -EINVAL;
> @@ -554,6 +560,9 @@ static int imx_mu_startup(struct mbox_chan *chan)
>         int ret;
>
>         pm_runtime_get_sync(priv->dev);
> +       if (cp->type == IMX_MU_TYPE_TXDB_V2)
> +               return 0;
> +
>         if (cp->type == IMX_MU_TYPE_TXDB) {
>                 /* Tx doorbell don't have ACK support */
>                 tasklet_init(&cp->txdb_tasklet, imx_mu_txdb_tasklet,
> @@ -595,6 +604,11 @@ static void imx_mu_shutdown(struct mbox_chan *chan)
>         int ret;
>         u32 sr;
>
> +       if (cp->type == IMX_MU_TYPE_TXDB_V2) {
> +               pm_runtime_put_sync(priv->dev);
> +               return;
> +       }
> +
>         if (cp->type == IMX_MU_TYPE_TXDB) {
>                 tasklet_kill(&cp->txdb_tasklet);
>                 pm_runtime_put_sync(priv->dev);
> @@ -671,6 +685,7 @@ static struct mbox_chan *imx_mu_specific_xlate(struct mbox_controller *mbox,
>  static struct mbox_chan * imx_mu_xlate(struct mbox_controller *mbox,
>                                        const struct of_phandle_args *sp)
>  {
> +       struct mbox_chan *p_chan;
>         u32 type, idx, chan;
>
>         if (sp->args_count != 2) {
> @@ -680,14 +695,25 @@ static struct mbox_chan * imx_mu_xlate(struct mbox_controller *mbox,
>
>         type = sp->args[0]; /* channel type */
>         idx = sp->args[1]; /* index */
> -       chan = type * 4 + idx;
>
> +       /* RST only supports 1 channel */
> +       if ((type == IMX_MU_TYPE_RST) && idx) {
> +               dev_err(mbox->dev, "Invalid RST channel %d\n", idx);
> +               return ERR_PTR(-EINVAL);
> +       }

I don't understand how is this related to introduction of a new
doorbell channel. Can you please
add it in a separate patch with proper explanation?


> +
> +       chan = type * 4 + idx;
>         if (chan >= mbox->num_chans) {
>                 dev_err(mbox->dev, "Not supported channel number: %d. (type: %d, idx: %d)\n", chan, type, idx);
>                 return ERR_PTR(-EINVAL);
>         }
>
> -       return &mbox->chans[chan];
> +       p_chan = &mbox->chans[chan];
> +
> +       if (type == IMX_MU_TYPE_TXDB_V2)
> +               p_chan->txdone_method = TXDONE_BY_ACK;
> +
> +       return p_chan;
>  }
>
>  static struct mbox_chan *imx_mu_seco_xlate(struct mbox_controller *mbox,
>
> --
> 2.37.1
>