[PATCH v7 2/2] mailbox: mediatek: Add mtk-vcp-mailbox driver

[Jassi Brar]

On Thu, Oct 2, 2025 at 3:42 AM Jjian Zhou <jjian.zhou at mediatek.com> wrote:
>
> Add mtk-vcp-mailbox driver to support the communication with
> VCP remote microprocessor.
>
> Signed-off-by: Jjian Zhou <jjian.zhou at mediatek.com>
> ---
>  drivers/mailbox/Kconfig                 |   9 ++
>  drivers/mailbox/Makefile                |   2 +
>  drivers/mailbox/mtk-vcp-mailbox.c       | 170 ++++++++++++++++++++++++
>  include/linux/mailbox/mtk-vcp-mailbox.h |  32 +++++
>  4 files changed, 213 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..94dac59ca32b
> --- /dev/null
> +++ b/drivers/mailbox/mtk-vcp-mailbox.c
> @@ -0,0 +1,170 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2025 MediaTek Corporation. All rights reserved.
> + * Author: Jjian Zhou <jjian.zhou. at 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 {
> +       struct mbox_controller mbox;
> +       void __iomem *base;
> +       struct device *dev;
> +       const struct mtk_vcp_mbox_cfg *cfg;
> +       struct mtk_ipi_info ipi_recv;
> +       struct mbox_chan chans;
> +};
> +
> +struct mtk_vcp_mbox_cfg {
> +       u16 set_in;
> +       u16 clr_out;
> +};
> +
> +static irqreturn_t mtk_vcp_mbox_irq_thread(int irq, void *data)
> +{
> +       struct mtk_vcp_mbox *priv = data;
> +
> +       /* get irq status */
> +       priv->ipi_recv.irq_status = readl(priv->base + priv->cfg->clr_out);
> +
> +       __ioread32_copy(priv->ipi_recv.msg, priv->base,
> +                       MTK_VCP_MBOX_SLOT_MAX_SIZE / 4);
> +
> +       mbox_chan_received_data(&priv->chans, &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[0];
> +}
> +
> +static int mtk_vcp_mbox_send_data(struct mbox_chan *chan, void *data)
> +{
> +       struct mtk_vcp_mbox *priv = chan->con_priv;
> +       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);
> +       if (status & BIT(ipi_info->index)) {
> +               dev_warn(priv->dev, "mailbox IPI %d is busy.\n", ipi_info->id);
> +               return -EBUSY;
> +       }
> +
> +       if (ipi_info->slot_ofs + ipi_info->len > MTK_VCP_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 = chan->con_priv;
> +
> +       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;
> +       struct mbox_controller *mbox;
> +       int ret, irq;
> +
> +       priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +       if (!priv)
> +               return -ENOMEM;
> +
> +       priv->dev = dev;
> +       priv->chans.con_priv = priv;
> +       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 = &priv->chans;
> +
> +       priv->ipi_recv.msg = devm_kzalloc(dev, MTK_VCP_MBOX_SLOT_MAX_SIZE
> +                                         GFP_KERNEL);
>
Please compile-test at least before submitting. Dropping it, sorry.

-jassi