Re: [PATCH v6 2/2] mailbox: mediatek: Add mtk-vcp-mailbox driver

[AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>]

Il 26/09/25 11:05, Jjian Zhou ha scritto:
> Add mtk-vcp-mailbox driver to support the communication with
> VCP remote microprocessor.
> 
> Signed-off-by: Jjian Zhou <jjian.zhou@mediatek.com>
> ---
>   drivers/mailbox/Kconfig                 |   9 ++
>   drivers/mailbox/Makefile                |   2 +
>   drivers/mailbox/mtk-vcp-mailbox.c       | 168 ++++++++++++++++++++++++
>   include/linux/mailbox/mtk-vcp-mailbox.h |  32 +++++
>   4 files changed, 211 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..a2a80d124e50
> --- /dev/null
> +++ b/drivers/mailbox/mtk-vcp-mailbox.c
> @@ -0,0 +1,168 @@
> +// 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 {
> +	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 {
> +	u32 set_in;
> +	u32 clr_out;

u16 is enough for both register offsets, at least for now - and I suspect it's
going to be enough forever.

> +};
> +
> +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, 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) & BIT(ipi_info->index);

status = readl(priv->base + priv->cfg->set_in);
if (status & 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 = 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, 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;
> +

Please set the driver data before requesting the interrupt: what happens if the
ISR is run before having driver data available otherwise?! :-)

> +	ret = devm_request_threaded_irq(dev, irq, NULL,
> +					mtk_vcp_mbox_irq_thread, IRQF_ONESHOT,
> +					dev_name(dev), priv);
> +	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,
> +};
> +
> +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 */

Please, change this definition to MTK_VCP_MBOX_SLOT_MAX_SIZE

Cheers,
Angelo

> +
> +/**
> + * 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