Re: [PATCH v5 2/2] mailbox: mediatek: Add mtk-vcp-mailbox driver

["Jjian Zhou (周建)" <Jjian.Zhou@mediatek.com>]

On Fri, 2025-08-22 at 13:48 +0800, Chen-Yu Tsai wrote:
> External email : Please do not click links or open attachments until
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> 
> 
> On Fri, Aug 22, 2025 at 10:12 AM Jjian Zhou <jjian.zhou@mediatek.com>
> wrote:
> > 
> > Add mtk-vcp-mailbox driver to support the communication with
> > VCP remote microprocessor.
> > 
> > Signed-off-by: Jjian Zhou <jjian.zhou@mediatek.com>
> 
> Reviewed-by: Chen-Yu Tsai <wenst@chromium.org>
> 
> A couple minor comments below.
> 
> > ---
> >  drivers/mailbox/Kconfig                 |   9 ++
> >  drivers/mailbox/Makefile                |   2 +
> >  drivers/mailbox/mtk-vcp-mailbox.c       | 174
> > ++++++++++++++++++++++++
> >  include/linux/mailbox/mtk-vcp-mailbox.h |  32 +++++
> >  4 files changed, 217 insertions(+)
> >  create mode 100644 drivers/mailbox/mtk-vcp-mailbox.c
> >  create mode 100644 include/linux/mailbox/mtk-vcp-mailbox.h
> > 
> > diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> > index 02432d4a5ccd..c28bdb855663 100644
> > --- a/drivers/mailbox/Kconfig
> > +++ b/drivers/mailbox/Kconfig
> > @@ -294,6 +294,15 @@ config MTK_CMDQ_MBOX
> >           critical time limitation, such as updating display
> > configuration
> >           during the vblank.
> > 
> > +config MTK_VCP_MBOX
> > +       tristate "MediaTek VCP Mailbox Support"
> > +       depends on ARCH_MEDIATEK || COMPILE_TEST
> > +       help
> > +         Say yes here to add support for the MediaTek VCP mailbox
> > driver.
> > +         The mailbox implementation provides access from the
> > application
> > +         processor to Video Companion Processor Unit.
> > +         If unsure say N.
> > +
> >  config ZYNQMP_IPI_MBOX
> >         tristate "Xilinx ZynqMP IPI Mailbox"
> >         depends on ARCH_ZYNQMP && OF
> > diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> > index 98a68f838486..07278871d254 100644
> > --- a/drivers/mailbox/Makefile
> > +++ b/drivers/mailbox/Makefile
> > @@ -63,6 +63,8 @@ obj-$(CONFIG_MTK_ADSP_MBOX)   += mtk-adsp-
> > mailbox.o
> > 
> >  obj-$(CONFIG_MTK_CMDQ_MBOX)    += mtk-cmdq-mailbox.o
> > 
> > +obj-$(CONFIG_MTK_VCP_MBOX)     += mtk-vcp-mailbox.o
> > +
> >  obj-$(CONFIG_ZYNQMP_IPI_MBOX)  += zynqmp-ipi-mailbox.o
> > 
> >  obj-$(CONFIG_SUN6I_MSGBOX)     += sun6i-msgbox.o
> > diff --git a/drivers/mailbox/mtk-vcp-mailbox.c
> > b/drivers/mailbox/mtk-vcp-mailbox.c
> > new file mode 100644
> > index 000000000000..6f48215896d2
> > --- /dev/null
> > +++ b/drivers/mailbox/mtk-vcp-mailbox.c
> > @@ -0,0 +1,174 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2025 MediaTek Corporation. All rights reserved.
> > + * Author: Jjian Zhou <jjian.zhou.@mediatek.com>
> > + */
> > +
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/mailbox_controller.h>
> > +#include <linux/mailbox/mtk-vcp-mailbox.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +
> > +struct mtk_vcp_mbox_priv {
> > +       void __iomem *base;
> > +       struct device *dev;
> > +       struct mbox_controller mbox;
> > +       const struct mtk_vcp_mbox_cfg *cfg;
> > +       struct mtk_ipi_info ipi_recv;
> > +};
> > +
> > +struct mtk_vcp_mbox_cfg {
> > +       u32 set_in;
> > +       u32 clr_out;
> > +};
> > +
> > +static inline struct mtk_vcp_mbox_priv
> > *get_mtk_vcp_mbox_priv(struct mbox_controller *mbox)
> > +{
> > +       return container_of(mbox, struct mtk_vcp_mbox_priv, mbox);
> > +}
> > +
> > +static irqreturn_t mtk_vcp_mbox_irq_thread(int irq, void *data)
> > +{
> > +       struct mbox_chan *chan = data;
> > +       struct mtk_vcp_mbox_priv *priv =
> > get_mtk_vcp_mbox_priv(chan->mbox);
> 
> Since there's only one mailbox, you can just pass the private data,
> instead of passing the mbox_chan.

I got it. Modification like below:

struct mtk_vcp_mbox_priv *priv = data;
ret = devm_request_threaded_irq(dev, irq, NULL,
                                mtk_vcp_mbox_irq_thread, IRQF_ONESHOT,
                                dev_name(dev), priv);

> 
> > +
> > +       /* get irq status */
> > +       priv->ipi_recv.irq_status = readl(priv->base + priv->cfg-
> > >clr_out);
> > +
> > +       __ioread32_copy(priv->ipi_recv.msg, priv->base,
> > MBOX_SLOT_MAX_SIZE / 4);
> > +
> > +       mbox_chan_received_data(chan, &priv->ipi_recv);
> > +
> > +       /* clear irq status */
> > +       writel(priv->ipi_recv.irq_status, priv->base + priv->cfg-
> > >clr_out);
> > +
> > +       return IRQ_HANDLED;
> > +}
> > +
> > +static struct mbox_chan *mtk_vcp_mbox_xlate(struct mbox_controller
> > *mbox,
> > +                                           const struct
> > of_phandle_args *sp)
> > +{
> > +       if (sp->args_count)
> > +               return NULL;
> > +
> > +       return mbox->chans;
> > +}
> > +
> > +static int mtk_vcp_mbox_send_data(struct mbox_chan *chan, void
> > *data)
> > +{
> > +       struct mtk_vcp_mbox_priv *priv =
> > get_mtk_vcp_mbox_priv(chan->mbox);
> > +       struct mtk_ipi_info *ipi_info = data;
> > +       u32 status;
> > +
> > +       if (!ipi_info->msg) {
> > +               dev_err(priv->dev, "msg buffer is NULL.\n");
> > +               return -EINVAL;
> > +       }
> > +
> > +       status = readl(priv->base + priv->cfg->set_in) &
> > BIT(ipi_info->index);
> > +       if (status) {
> > +               dev_warn(priv->dev, "mailbox IPI %d is busy.\n",
> > ipi_info->id);
> > +               return -EBUSY;
> > +       }
> > +
> > +       if (ipi_info->slot_ofs + ipi_info->len >
> > MBOX_SLOT_MAX_SIZE)
> > +               return -EINVAL;
> > +       __iowrite32_copy(priv->base + ipi_info->slot_ofs, ipi_info-
> > >msg,
> > +                        ipi_info->len);
> > +
> > +       writel(BIT(ipi_info->index), priv->base + priv->cfg-
> > >set_in);
> > +
> > +       return 0;
> > +}
> > +
> > +static bool mtk_vcp_mbox_last_tx_done(struct mbox_chan *chan)
> > +{
> > +       struct mtk_ipi_info *ipi_info = chan->active_req;
> > +       struct mtk_vcp_mbox_priv *priv =
> > get_mtk_vcp_mbox_priv(chan->mbox);
> > +
> > +       return !(readl(priv->base + priv->cfg->set_in) &
> > BIT(ipi_info->index));
> > +}
> > +
> > +static const struct mbox_chan_ops mtk_vcp_mbox_chan_ops = {
> > +       .send_data      = mtk_vcp_mbox_send_data,
> > +       .last_tx_done   = mtk_vcp_mbox_last_tx_done,
> > +};
> > +
> > +static int mtk_vcp_mbox_probe(struct platform_device *pdev)
> > +{
> > +       struct device *dev = &pdev->dev;
> > +       struct mtk_vcp_mbox_priv *priv;
> > +       struct mbox_controller *mbox;
> > +       int ret, irq;
> > +
> > +       priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> > +       if (!priv)
> > +               return -ENOMEM;
> > +
> > +       priv->dev = dev;
> > +       mbox = &priv->mbox;
> > +       mbox->dev = dev;
> > +       mbox->ops = &mtk_vcp_mbox_chan_ops;
> > +       mbox->txdone_irq = false;
> > +       mbox->txdone_poll = true;
> > +       mbox->of_xlate = mtk_vcp_mbox_xlate;
> > +       mbox->num_chans = 1;
> > +       mbox->chans = devm_kzalloc(dev, sizeof(*mbox->chans),
> > GFP_KERNEL);
> > +       if (!mbox->chans)
> > +               return -ENOMEM;
> > +
> > +       priv->ipi_recv.msg = devm_kzalloc(dev, MBOX_SLOT_MAX_SIZE,
> > GFP_KERNEL);
> > +       if (!priv->ipi_recv.msg)
> > +               return -ENOMEM;
> > +
> > +       priv->base = devm_platform_ioremap_resource(pdev, 0);
> > +       if (IS_ERR(priv->base))
> > +               return PTR_ERR(priv->base);
> > +
> > +       priv->cfg = of_device_get_match_data(dev);
> > +       if (!priv->cfg)
> > +               return -EINVAL;
> > +
> > +       irq = platform_get_irq(pdev, 0);
> > +       if (irq < 0)
> > +               return irq;
> > +
> > +       ret = devm_request_threaded_irq(dev, irq, NULL,
> > +                                       mtk_vcp_mbox_irq_thread,
> > IRQF_ONESHOT,
> > +                                       dev_name(dev), mbox-
> > >chans);
> > +       if (ret < 0)
> > +               return ret;
> > +
> > +       platform_set_drvdata(pdev, priv);
> > +
> > +       return devm_mbox_controller_register(dev, &priv->mbox);
> > +}
> > +
> > +static const struct mtk_vcp_mbox_cfg mt8196_cfg = {
> > +       .set_in         = 0x100,
> > +       .clr_out        = 0x10C,
> 
>                                 ^ use lowercase for hex numbers.

Thanks.

> 
> > +};
> > +
> > +static const struct of_device_id mtk_vcp_mbox_of_match[] = {
> > +       { .compatible = "mediatek,mt8196-vcp-mbox", .data =
> > &mt8196_cfg },
> > +       {},
> > +};
> > +MODULE_DEVICE_TABLE(of, mtk_vcp_mbox_of_match);
> > +
> > +static struct platform_driver mtk_vcp_mbox_driver = {
> > +       .probe          = mtk_vcp_mbox_probe,
> > +       .driver = {
> > +               .name   = "mtk_vcp_mbox",
> > +               .of_match_table = mtk_vcp_mbox_of_match,
> > +       },
> > +};
> > +module_platform_driver(mtk_vcp_mbox_driver);
> > +
> > +MODULE_AUTHOR("Jjian Zhou <jjian.zhou@mediatek.com>");
> > +MODULE_DESCRIPTION("MTK VCP Mailbox Controller");
> > +MODULE_LICENSE("GPL");
> > diff --git a/include/linux/mailbox/mtk-vcp-mailbox.h
> > b/include/linux/mailbox/mtk-vcp-mailbox.h
> > new file mode 100644
> > index 000000000000..143fb0d06e30
> > --- /dev/null
> > +++ b/include/linux/mailbox/mtk-vcp-mailbox.h
> > @@ -0,0 +1,32 @@
> > +/* SPDX-License-Identifier: (GPL-2.0 OR MIT) */
> > +/*
> > + * Copyright (c) 2025 MediaTek Inc.
> > + */
> > +
> > +#ifndef __MTK_VCP_MAILBOX_H__
> > +#define __MTK_VCP_MAILBOX_H__
> > +
> > +#define MBOX_SLOT_MAX_SIZE     0x100 /* mbox max slot size */
> > +
> > +/**
> > + * struct mtk_ipi_info - mailbox message info for mtk-vcp-mailbox
> > + * @msg: The share buffer between IPC and mailbox driver
> > + * @len: Message length
> > + * @id: This is for identification purposes and not actually used
> > + *     by the mailbox hardware.
> > + * @index: The signal number of the mailbox message.
> > + * @slot_ofs: Data slot offset.
> > + * @irq_status: Captures incoming signals for the RX path.
> > + *
> > + * It is used between IPC with mailbox driver.
> > + */
> > +struct mtk_ipi_info {
> > +       void *msg;
> > +       u32 len;
> > +       u32 id;
> > +       u32 index;
> > +       u32 slot_ofs;
> > +       u32 irq_status;
> > +};
> > +
> > +#endif
> > --
> > 2.46.0
> >