[PATCH 3/3] mailbox: mediatek: Add mtk-apu-mailbox driver
AngeloGioacchino Del Regno
angelogioacchino.delregno at collabora.com
Thu Oct 24 04:04:37 PDT 2024
Il 24/10/24 11:25, Karl.Li ha scritto:
> From: Karl Li <karl.li at mediatek.com>
>
> Add mtk-apu-mailbox driver to support the communication with
> APU remote microprocessor.
>
> Also, the mailbox hardware contains extra spare (scratch) registers
> that other hardware blocks use to communicate through.
> Expose these with custom mtk_apu_mbox_(read|write)() functions.
>
> Signed-off-by: Karl Li <karl.li at mediatek.com>
> ---
> drivers/mailbox/Kconfig | 9 +
> drivers/mailbox/Makefile | 2 +
> drivers/mailbox/mtk-apu-mailbox.c | 222 ++++++++++++++++++++++++
> include/linux/mailbox/mtk-apu-mailbox.h | 20 +++
> 4 files changed, 253 insertions(+)
> create mode 100644 drivers/mailbox/mtk-apu-mailbox.c
> create mode 100644 include/linux/mailbox/mtk-apu-mailbox.h
>
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 6fb995778636..2338e08a110a 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -240,6 +240,15 @@ config MTK_ADSP_MBOX
> between processors with ADSP. It will place the message to share
> buffer and will access the ipc control.
>
> +config MTK_APU_MBOX
> + tristate "MediaTek APU Mailbox Support"
> + depends on ARCH_MEDIATEK || COMPILE_TEST
> + help
> + Say yes here to add support for the MediaTek APU Mailbox
> + driver. The mailbox implementation provides access from the
> + application processor to the MediaTek AI Processing Unit.
> + If unsure say N.
> +
> config MTK_CMDQ_MBOX
> tristate "MediaTek CMDQ Mailbox Support"
> depends on ARCH_MEDIATEK || COMPILE_TEST
> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> index 3c3c27d54c13..6b6dcc78d644 100644
> --- a/drivers/mailbox/Makefile
> +++ b/drivers/mailbox/Makefile
> @@ -53,6 +53,8 @@ obj-$(CONFIG_STM32_IPCC) += stm32-ipcc.o
>
> obj-$(CONFIG_MTK_ADSP_MBOX) += mtk-adsp-mailbox.o
>
> +obj-$(CONFIG_MTK_APU_MBOX) += mtk-apu-mailbox.o
> +
> obj-$(CONFIG_MTK_CMDQ_MBOX) += mtk-cmdq-mailbox.o
>
> obj-$(CONFIG_ZYNQMP_IPI_MBOX) += zynqmp-ipi-mailbox.o
> diff --git a/drivers/mailbox/mtk-apu-mailbox.c b/drivers/mailbox/mtk-apu-mailbox.c
> new file mode 100644
> index 000000000000..b347ebd34ef7
> --- /dev/null
> +++ b/drivers/mailbox/mtk-apu-mailbox.c
> @@ -0,0 +1,222 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2024 MediaTek Inc.
> + */
> +
> +#include <asm/io.h>
> +#include <linux/bits.h>
> +#include <linux/interrupt.h>
> +#include <linux/mailbox_controller.h>
> +#include <linux/mailbox/mtk-apu-mailbox.h>
> +#include <linux/platform_device.h>
> +
> +#define INBOX (0x0)
> +#define OUTBOX (0x20)
> +#define INBOX_IRQ (0xc0)
> +#define OUTBOX_IRQ (0xc4)
> +#define INBOX_IRQ_MASK (0xd0)
> +
> +#define SPARE_OFF_START (0x40)
> +#define SPARE_OFF_END (0xB0)
> +
> +struct mtk_apu_mailbox {
> + struct device *dev;
> + void __iomem *regs;
> + struct mbox_controller controller;
struct mbox_controller mbox;
...it's shorter and consistent with at least other MTK mailbox drivers.
> + u32 msgs[MSG_MBOX_SLOTS];
Just reuse struct mtk_apu_mailbox_msg instead.....
> +};
> +
> +struct mtk_apu_mailbox *g_mbox;
That global struct must disappear - and if you use the mailbox API correctly
it's even simple.
Also, you want something like....
static inline struct mtk_apu_mailbox *get_mtk_apu_mailbox(struct mbox_controller *mbox)
{
return container_of(mbox, struct mtk_apu_mailbox, mbox);
}
> +
> +static irqreturn_t mtk_apu_mailbox_irq_top_half(int irq, void *dev_id)
> +{
static irqreturn_t mtk_apu_mailbox_irq(int irq, void *data)
{
struct mbox_chan *chan = data;
struct mtk_apu_mailbox = get_mtk_apu_mailbox(chan->mbox);
> + struct mtk_apu_mailbox *mbox = dev_id;
> + struct mbox_chan *link = &mbox->controller.chans[0];
> + int i;
> +
> + for (i = 0; i < MSG_MBOX_SLOTS; i++)
> + mbox->msgs[i] = readl(mbox->regs + OUTBOX + i * sizeof(u32));
> +
> + mbox_chan_received_data(link, &mbox->msgs);
> +
> + return IRQ_WAKE_THREAD;
> +}
> +
> +static irqreturn_t mtk_apu_mailbox_irq_btm_half(int irq, void *dev_id)
....mtk_apu_mailbox_irq_thread(...)
> +{
> + struct mtk_apu_mailbox *mbox = dev_id;
> + struct mbox_chan *link = &mbox->controller.chans[0];
> +
> + mbox_chan_received_data_bh(link, &mbox->msgs);
I don't think that you really need this _bh variant, looks more like you wanted
to have two callbacks instead of one.
You can instead have one callback and vary functionality based based on reading
a variable to decide what to actually do inside. Not a big deal.
> + writel(readl(mbox->regs + OUTBOX_IRQ), mbox->regs + OUTBOX_IRQ);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int mtk_apu_mailbox_send_data(struct mbox_chan *chan, void *data)
> +{
> + struct mtk_apu_mailbox *mbox = container_of(chan->mbox,
> + struct mtk_apu_mailbox,
> + controller);
> + struct mtk_apu_mailbox_msg *msg = data;
> + int i;
> +
> + if (msg->send_cnt <= 0 || msg->send_cnt > MSG_MBOX_SLOTS) {
> + dev_err(mbox->dev, "%s: invalid send_cnt %d\n", __func__, msg->send_cnt);
> + return -EINVAL;
> + }
> +
> + /*
> + * Mask lowest "send_cnt-1" interrupts bits, so the interrupt on the other side
> + * triggers only after the last data slot is written (sent).
> + */
> + writel(GENMASK(msg->send_cnt - 2, 0), mbox->regs + INBOX_IRQ_MASK);
> + for (i = 0; i < msg->send_cnt; i++)
> + writel(msg->data[i], mbox->regs + INBOX + i * sizeof(u32));
> +
> + return 0;
> +}
> +
> +static bool mtk_apu_mailbox_last_tx_done(struct mbox_chan *chan)
> +{
> + struct mtk_apu_mailbox *mbox = container_of(chan->mbox,
> + struct mtk_apu_mailbox,
> + controller);
> +
> + return readl(mbox->regs + INBOX_IRQ) == 0;
> +}
> +
> +static const struct mbox_chan_ops mtk_apu_mailbox_ops = {
> + .send_data = mtk_apu_mailbox_send_data,
> + .last_tx_done = mtk_apu_mailbox_last_tx_done,
> +};
> +
> +/**
> + * mtk_apu_mbox_write - Write value to specifice mtk_apu_mbox spare register.
> + * @val: Value to be written.
> + * @offset: Offset of the spare register.
> + *
> + * Return: 0 if successful
> + * negative value if error happened
> + */
> +int mtk_apu_mbox_write(u32 val, u32 offset)
> +{
> + if (!g_mbox) {
> + pr_err("mtk apu mbox was not initialized, stop writing register\n");
> + return -ENODEV;
> + }
> +
> + if (offset < SPARE_OFF_START || offset >= SPARE_OFF_END) {
> + dev_err(g_mbox->dev, "Invalid offset %d for mtk apu mbox spare register\n", offset);
> + return -EINVAL;
> + }
> +
> + writel(val, g_mbox->regs + offset);
There's something odd in what you're doing here, why would you ever need
a function that performs a writel just like that? What's the purpose?
What are you writing to the spare registers?
For which reason?
I think you can avoid (read this as: you *have to* avoid) having such a
function around.
> + return 0;
> +}
> +EXPORT_SYMBOL_NS(mtk_apu_mbox_write, MTK_APU_MAILBOX);
> +
> +/**
> + * mtk_apu_mbox_read - Read value to specifice mtk_apu_mbox spare register.
> + * @offset: Offset of the spare register.
> + * @val: Pointer to store read value.
> + *
> + * Return: 0 if successful
> + * negative value if error happened
> + */
> +int mtk_apu_mbox_read(u32 offset, u32 *val)
> +{
> + if (!g_mbox) {
> + pr_err("mtk apu mbox was not initialized, stop reading register\n");
> + return -ENODEV;
> + }
> +
> + if (offset < SPARE_OFF_START || offset >= SPARE_OFF_END) {
> + dev_err(g_mbox->dev, "Invalid offset %d for mtk apu mbox spare register\n", offset);
> + return -EINVAL;
> + }
> +
> + *val = readl(g_mbox->regs + offset);
> +
Same goes for this one.
> + return 0;
> +}
> +EXPORT_SYMBOL_NS(mtk_apu_mbox_read, MTK_APU_MAILBOX);
> +
> +static int mtk_apu_mailbox_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct mtk_apu_mailbox *mbox;
> + int irq = -1, ret = 0;
> +
> + mbox = devm_kzalloc(dev, sizeof(*mbox), GFP_KERNEL);
> + if (!mbox)
> + return -ENOMEM;
> +
> + mbox->dev = dev;
> + platform_set_drvdata(pdev, mbox);
> +
Please move the platform_get_irq call here or anyway before registering the
mbox controller: in case anything goes wrong, devm won't have to unregister
the mbox afterwards because it never got registered in the first place.
> + mbox->regs = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(mbox->regs))
> + return PTR_ERR(mbox->regs);
> +
> + mbox->controller.txdone_irq = false;
> + mbox->controller.txdone_poll = true;
> + mbox->controller.txpoll_period = 1;
> + mbox->controller.ops = &mtk_apu_mailbox_ops;
> + mbox->controller.dev = dev;
> + /*
> + * Here we only register 1 mbox channel.
> + * The remaining channels are used by other modules.
What other modules? I don't really see any - so please at least explain that in the
commit description.
> + */
> + mbox->controller.num_chans = 1;
> + mbox->controller.chans = devm_kcalloc(dev, mbox->controller.num_chans,
> + sizeof(*mbox->controller.chans),
> + GFP_KERNEL);
> + if (!mbox->controller.chans)
> + return -ENOMEM;
> +
> + ret = devm_mbox_controller_register(dev, &mbox->controller);
> + if (ret)
> + return ret;
> +
> + irq = platform_get_irq(pdev, 0);
> + if (irq < 0)
> + return irq;
> +
> + ret = devm_request_threaded_irq(dev, irq, mtk_apu_mailbox_irq_top_half,
> + mtk_apu_mailbox_irq_btm_half, IRQF_ONESHOT,
> + dev_name(dev), mbox);
pass mbox->chans to the isr
> + if (ret)
> + return dev_err_probe(dev, ret, "Failed to request IRQ\n");
> +
> + g_mbox = mbox;
> +
> + dev_dbg(dev, "registered mtk apu mailbox\n");
> +
> + return 0;
> +}
> +
> +static void mtk_apu_mailbox_remove(struct platform_device *pdev)
> +{
> + g_mbox = NULL;
> +}
> +
> +static const struct of_device_id mtk_apu_mailbox_of_match[] = {
> + { .compatible = "mediatek,mt8188-apu-mailbox" },
> + { .compatible = "mediatek,mt8196-apu-mailbox" },
Just mediatek,mt8188-apu-mailbox is fine; you can allow mt8196==mt8188 in the
binding instead.
> + {}
> +};
> +MODULE_DEVICE_TABLE(of, mtk_apu_mailbox_of_match);
> +
> +static struct platform_driver mtk_apu_mailbox_driver = {
> + .probe = mtk_apu_mailbox_probe,
> + .remove = mtk_apu_mailbox_remove,
You don't need this remove callback, since g_mbox has to disappear :-)
> + .driver = {
> + .name = "mtk-apu-mailbox",
> + .of_match_table = mtk_apu_mailbox_of_match,
> + },
> +};
> +
> +module_platform_driver(mtk_apu_mailbox_driver);
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("MediaTek APU Mailbox Driver");
> diff --git a/include/linux/mailbox/mtk-apu-mailbox.h b/include/linux/mailbox/mtk-apu-mailbox.h
> new file mode 100644
> index 000000000000..d1457d16ce9b
> --- /dev/null
> +++ b/include/linux/mailbox/mtk-apu-mailbox.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2024 MediaTek Inc.
> + *
> + */
> +
> +#ifndef __MTK_APU_MAILBOX_H__
> +#define __MTK_APU_MAILBOX_H__
> +
> +#define MSG_MBOX_SLOTS (8)
> +
> +struct mtk_apu_mailbox_msg {
> + int send_cnt;
u8 data_cnt;
> + u32 data[MSG_MBOX_SLOTS];
With hardcoded slots, what happens when we get a new chip in the future that
supports more slots?
Please think about this now and make the implementation flexible before that
happens because, at a later time, it'll be harder.
Regards,
Angelo
> +};
> +
> +int mtk_apu_mbox_write(u32 val, u32 offset);
> +int mtk_apu_mbox_read(u32 offset, u32 *val);
> +
> +#endif /* __MTK_APU_MAILBOX_H__ */
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