On Thu, 2024-12-05 at 07:05 +0000, Karl Li (李智嘉) wrote:
> Dead maintainers,
"Dear" maintainers. Really sorry for the typo...
>
> I hope you're doing well. Just a warm reminder that we're following
> up
> on these patch and really appreciate any feedback you might have.
>
> Thanks you in advance for your review.
>
> Regards,
> Karl
>
> On Tue, 2024-10-29 at 16:27 +0800, Karl Li wrote:
> > On Mon, 2024-10-28 at 14:16 +0800, Chen-Yu Tsai wrote:
> > >
> > > External email : Please do not click links or open attachments
> > > until
> > > you have verified the sender or the content.
> > >
> > >
> > > On Thu, Oct 24, 2024 at 7:13 PM AngeloGioacchino Del Regno
> > > <angelogioacchino.delregno@xxxxxxxxxxxxx> wrote:
> > > >
> > > > Il 24/10/24 11:25, Karl.Li ha scritto:
> > > > > From: Karl Li <karl.li@xxxxxxxxxxxx>
> > > > >
> > > > > 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@xxxxxxxxxxxx>
> > > > > ---
> > > > > 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.
> > >
> > > The problem is that they need something with different semantics.
> > > mbox_chan_received_data() is atomic only.
> >
> > Yes, as Chen-Yu said, we want to have another callback which can
> > run
> > under non-atomic semantic.
> > Even though we change the function based in the callback function
> > of
> > mbox_chan_received_data(), it is still non-atomic for the bottom-
> > half
> > handler.
> >
> > >
> > > > > + 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'll leave the explaining to Karl, but based on internal reviews
> > > for
> > > the
> > > previous generation, it looked like passing values to/from the
> > > MCU.
> > >
> >
> > The main reason we want to access the APU mailbox spare registers
> > is
> > to
> > ensure that we can configure the necessary settings before the APU
> > firmware becomes fully operational.
> >
> > At the early stage, the communication pathways between the APU and
> > the
> > Linux Kernel aren't yet available, so these spare registers are
> > needed
> > for passing the initial configuration data.
> >
> > > > I think you can avoid (read this as: you *have to* avoid)
> > > > having
> > > > such a
> > > > function around.
> > >
> > > Again, during the previous round of internal reviews, I had
> > > thought
> > > about modeling these as extra mbox channels. I may have even
> > > asked
> > > about this on IRC.
> > >
> > > The problem is that it doesn't really have mbox semantics. They
> > > are
> > > just shared registers with no send/receive notification. So at
> > > the
> > > very least, there's nothing that will trigger a reception. I
> > > suppose
> > > we could make the .peek_data op trigger RX, but that's a really
> > > convoluted way to read just a register.
> > >
> > > The other option would be to have a syscon / custom exported
> > > regmap?
> > >
> > > > > + 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.
> > >
> > > To clarify, you mean _just_ platform_get_irq() and not
> > > request_irq
> > > as
> > > well.
> > >
> > > > > + 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.
> >
> > Sorry for any confusion caused by the above comment. To clarify,
> > the
> > comment was specific to the MT8188 platform, which is the legacy
> > platform compared to MT8196.
> > In the context of MT8188, the APU mailbox has multiple in/out
> > boxes,
> > and Linux only utilizes in/out box 0, while the others are reserved
> > for
> > different VMs.
> >
> > However, the APU mailbox hardware design in MT8196 differs from
> > that
> > of
> > MT8188, and in MT8196, Linux has full access to the APU mailbox.
> >
> > Given that this patch is primarily for the MT8196 platform, we will
> > remove the above comment in the next version of the patch.
> >
> > Thanks for your asking.
> >
> > Karl
> >
> > > >
> > > > > + */
> > > > > + 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?
> > >
> > > Seems like we can make it a flexible array member? But the
> > > problem
> > > then
> > > becomes how does the client know what the maximum length is. Or
> > > maybe
> > > it should already know given it's tied to a particular platform.
> > >
> > > In any case it becomes:
> > >
> > > struct mtk_apu_mailbox_msg {
> > > u8 data_size;
> > > u8 data[] __counted_by(data_size);
> > > };
> > >
> > > This can't be allocated on the stack if `data_size` isn't a
> > > compile
> > > time constant though; but again it shouldn't be a problem given
> > > the
> > > message size is tied to the client & its platform and should be
> > > constant anyway.
> > >
> > > The controller should just error out if the message is larger
> > > than
> > > what it can atomically send.
> > >
> > >
> > > ChenYu
> > >
> > > > 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__ */
> > > >
> > > >
> >
>
