Re: [PATCH v2 3/3] mailbox: sophgo: add mailbox driver for cv18x SoCs

From: Yuntao Dai
Date: Mon Jul 22 2024 - 13:02:34 EST

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In reply to: Samuel Holland: "Re: [PATCH v2 3/3] mailbox: sophgo: add mailbox driver for cv18x SoCs"
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From: Samuel Holland <samuel.holland@xxxxxxxxxx>
Sent: Friday, July 19, 2024 09:35
To: Yuntao Dai <d1581209858@xxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx <linux-kernel@xxxxxxxxxxxxxxx>; devicetree@xxxxxxxxxxxxxxx <devicetree@xxxxxxxxxxxxxxx>; linux-riscv@xxxxxxxxxxxxxxxxxxx <linux-riscv@xxxxxxxxxxxxxxxxxxx>; jassisinghbrar@xxxxxxxxx <jassisinghbrar@xxxxxxxxx>; robh@xxxxxxxxxx <robh@xxxxxxxxxx>; krzk+dt@xxxxxxxxxx <krzk+dt@xxxxxxxxxx>; conor+dt@xxxxxxxxxx <conor+dt@xxxxxxxxxx>; unicorn_wang@xxxxxxxxxxx <unicorn_wang@xxxxxxxxxxx>; inochiama@xxxxxxxxxxx <inochiama@xxxxxxxxxxx>; paul.walmsley@xxxxxxxxxx <paul.walmsley@xxxxxxxxxx>; palmer@xxxxxxxxxxx <palmer@xxxxxxxxxxx>; aou@xxxxxxxxxxxxxxxxx <aou@xxxxxxxxxxxxxxxxx>
Subject: Re: [PATCH v2 3/3] mailbox: sophgo: add mailbox driver for cv18x SoCs

On 2024-07-14 11:36 AM, Yuntao Dai wrote:
> Add mailbox controller driver for cv18x SoCs, tested on mailbox-test
> client.
>
> Signed-off-by: Yuntao Dai <d1581209858@xxxxxxxx>
> ---
> drivers/mailbox/Kconfig | 11 ++
> drivers/mailbox/Makefile | 2 +
> drivers/mailbox/cv1800-mailbox.c | 203 +++++++++++++++++++++++++++++++
> 3 files changed, 216 insertions(+)
> create mode 100644 drivers/mailbox/cv1800-mailbox.c
>
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 3b8842c4a..db856ec7e 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -286,4 +286,15 @@ config QCOM_IPCC
> acts as an interrupt controller for receiving interrupts from clients.
> Say Y here if you want to build this driver.
>
> +config CV1800_MBOX
> + tristate "cv1800 mailbox"
> + depends on OF

This dependency is not necessary once the probe function is fixed (see below).

I will fix it.

> + depends on ARCH_SOPHGO || COMPILE_TEST
> + help
> + Mailbox driver implementation for Sophgo cv180x SoCs. This driver
> + can be used to send message between different processors in SoC. Any
> + processer can write data in a channel, and set co-responding register
> + to raise interrupt to notice another processor, and it is allowed to
> + send data to itself.
> +
> endif
> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> index 5cf2f54de..2c6db8c5c 100644
> --- a/drivers/mailbox/Makefile
> +++ b/drivers/mailbox/Makefile
> @@ -62,3 +62,5 @@ obj-$(CONFIG_SUN6I_MSGBOX) += sun6i-msgbox.o
> obj-$(CONFIG_SPRD_MBOX) += sprd-mailbox.o
>
> obj-$(CONFIG_QCOM_IPCC) += qcom-ipcc.o
> +
> +obj-$(CONFIG_CV1800_MBOX) += cv1800-mailbox.o
> \ No newline at end of file

Please add the missing newline.

I will fix it

> diff --git a/drivers/mailbox/cv1800-mailbox.c b/drivers/mailbox/cv1800-mailbox.c
> new file mode 100644
> index 000000000..a3b214b4d
> --- /dev/null
> +++ b/drivers/mailbox/cv1800-mailbox.c
> @@ -0,0 +1,203 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kfifo.h>
> +#include <linux/mailbox_controller.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define RECV_CPU 2
> +
> +#define MAILBOX_MAX_CHAN 0x0008
> +#define MAILBOX_DONE_OFFSET 0x0002
> +#define MAILBOX_CONTEXT_SIZE 0x0040
> +#define MAILBOX_CONTEXT_OFFSET 0x0400
> +
> +#define MBOX_EN_REG(cpu) (cpu << 2)
> +#define MBOX_DONE_REG(cpu) ((cpu << 2) + MAILBOX_DONE_OFFSET)
> +
> +#define MBOX_SET_CLR_REG(cpu) (0x10 + (cpu << 4))
> +#define MBOX_SET_INT_REG(cpu) (0x18 + (cpu << 4))
> +
> +#define MBOX_SET_REG 0x60
> +
> +/**
> + * cv1800 mailbox channel private data
> + * @idx: index of channel
> + * @cpu: send to which processor
> + */
> +struct cv1800_mbox_chan_priv {
> + int idx;
> + int cpu;
> +};
> +
> +struct cv1800_mbox {
> + struct mbox_controller mbox;
> + struct cv1800_mbox_chan_priv priv[MAILBOX_MAX_CHAN];
> + struct mbox_chan chans[MAILBOX_MAX_CHAN];
> + u64 __iomem *content[MAILBOX_MAX_CHAN];
> + void __iomem *mbox_base;
> + int recvid;
> +};
> +
> +static irqreturn_t cv1800_mbox_isr(int irq, void *dev_id)
> +{
> + struct cv1800_mbox *mbox = (struct cv1800_mbox *)dev_id;
> + size_t i;
> +
> + for (i = 0; i < MAILBOX_MAX_CHAN; i++) {
> + if (mbox->content[i] && mbox->chans[i].cl) {
> + mbox_chan_received_data(&mbox->chans[i],
> + mbox->content[i]);
> + mbox->content[i] = NULL;
> + return IRQ_HANDLED;

Are you sure you only want to handle one channel per interrupt? Should this be
"ret = IRQ_HANDLED;" or similar instead of early return? The same applies to
cv1800_mbox_irq().

I believe this approach can simplify the implementation. I utilize IRQ_ONESHOT to
prevent interrupt racing, thereby avoiding the need for locking mbox->content in
this scenario. And I see rockchip mailbox did the same thing.

> + }
> + }
> + return IRQ_NONE;
> +}
> +
> +static irqreturn_t cv1800_mbox_irq(int irq, void *dev_id)
> +{
> + struct cv1800_mbox *mbox = (struct cv1800_mbox *)dev_id;
> + u64 __iomem *addr;
> + u8 set, valid;
> + size_t i;
> +
> + set = readb(mbox->mbox_base + MBOX_SET_INT_REG(RECV_CPU));
> +
> + if (!set)
> + return IRQ_NONE;
> +
> + for (i = 0; i < MAILBOX_MAX_CHAN; i++) {
> + valid = set & (1 << i);
> + addr = (u64 *)(mbox->mbox_base + MAILBOX_CONTEXT_OFFSET) + i;
> + if (valid) {
> + mbox->content[i] = addr;
> + writeb(valid,
> + mbox->mbox_base + MBOX_SET_CLR_REG(RECV_CPU));
> + writeb(~valid, mbox->mbox_base + MBOX_EN_REG(RECV_CPU));
> + return IRQ_WAKE_THREAD;
> + }
> + }
> +
> + return IRQ_NONE;
> +}
> +
> +static int cv1800_mbox_send_data(struct mbox_chan *chan, void *data)
> +{
> + struct cv1800_mbox_chan_priv *priv =
> + (struct cv1800_mbox_chan_priv *)chan->con_priv;
> + struct cv1800_mbox *mbox = dev_get_drvdata(chan->mbox->dev);
> + u64 __iomem *addr;
> + u8 en, valid;
> +
> + int idx = priv->idx;
> + int cpu = priv->cpu;
> +
> + addr = (u64 *)(mbox->mbox_base + MAILBOX_CONTEXT_OFFSET) + idx;
> + memcpy_toio(addr, data, 8);
> +
> + valid = 1 << idx;
> + writeb(valid, mbox->mbox_base + MBOX_SET_CLR_REG(cpu));
> + en = readb(mbox->mbox_base + MBOX_EN_REG(cpu));
> + writeb(en | valid, mbox->mbox_base + MBOX_EN_REG(cpu));
> + writeb(valid, mbox->mbox_base + MBOX_SET_REG);
> +
> + return 0;
> +}
> +
> +static bool cv1800_last_tx_done(struct mbox_chan *chan)
> +{
> + return true;

Shouldn't this check MBOX_EN_REG(priv->cpu) or similar to check that the
receiver has read the message?

Yes, I think check MBOX_EN_REG(priv->cpu) is a good way to ensure content
has been writen into hardware. And I think driver should only send the
message and upper layer is responsible for ack and things like that.

There is a vendor implementation of linux mailbox and RTOS mailbox:
https://github.com/milkv-duo/duo-buildroot-sdk/blob/develop/linux_5.10/drivers/soc/cvitek/rtos_cmdqu/rtos_cmdqu.c
https://github.com/milkv-duo/duo-buildroot-sdk/blob/develop/freertos/cvitek/task/comm/src/riscv64/comm_main.c

These implementations define a protocol structure for communication between
linux and RTOS, the linux mailbox controller just need to provide API for
client and do not consider the content of msg.

> +}
> +
> +static const struct mbox_chan_ops cv1800_mbox_chan_ops = {
> + .send_data = cv1800_mbox_send_data,
> + .last_tx_done = cv1800_last_tx_done,
> +};
> +
> +static struct mbox_chan *cv1800_mbox_xlate(struct mbox_controller *mbox,
> + const struct of_phandle_args *spec)
> +{
> + struct cv1800_mbox_chan_priv *priv;
> +
> + int idx = spec->args[0];
> + int cpu = spec->args[1];
> +
> + if (idx >= mbox->num_chans)
> + return ERR_PTR(-EINVAL);
> +
> + priv = mbox->chans[idx].con_priv;
> + priv->cpu = cpu;
> +
> + return &mbox->chans[idx];
> +}
> +
> +static const struct of_device_id cv1800_mbox_of_match[] = {
> + { .compatible = "sophgo,cv1800-mailbox", },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, cv1800_mbox_of_match);
> +
> +static int cv1800_mbox_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct cv1800_mbox *mb;
> + int irq, idx, err;
> +
> + if (!dev->of_node)
> + return -ENODEV;

No need for this check.

I will fix it

> +
> + mb = devm_kzalloc(dev, sizeof(*mb), GFP_KERNEL);
> + if (!mb)
> + return -ENOMEM;
> +
> + mb->mbox_base = devm_of_iomap(dev, dev->of_node, 0, NULL);

Please use devm_platform_ioremap_resource() here, which abstracts away the OF node.

I will fix it

> + if (IS_ERR(mb->mbox_base))
> + return dev_err_probe(dev, PTR_ERR(mb->mbox_base),
> + "Failed to map resource\n");
> +
> + mb->mbox.dev = dev;
> + mb->mbox.chans = mb->chans;
> + mb->mbox.txdone_poll = true;
> + mb->mbox.ops = &cv1800_mbox_chan_ops;
> + mb->mbox.num_chans = MAILBOX_MAX_CHAN;
> + mb->mbox.of_xlate = cv1800_mbox_xlate;
> +
> + irq = platform_get_irq_byname(pdev, "mailbox");
> + err = devm_request_threaded_irq(dev, irq, cv1800_mbox_irq,
> + cv1800_mbox_isr, IRQF_ONESHOT,
> + dev_name(&pdev->dev), mb);
> + if (err < 0)
> + return dev_err_probe(dev, err, "Failed to register irq\n");
> +
> + for (idx = 0; idx < MAILBOX_MAX_CHAN; idx++) {
> + mb->priv[idx].idx = idx;
> + mb->mbox.chans[idx].con_priv = &mb->priv[idx];
> + }
> +
> + err = devm_mbox_controller_register(dev, &mb->mbox);
> + if (err)
> + return dev_err_probe(dev, err, "Failed to register mailbox\n");
> +
> + platform_set_drvdata(pdev, mb);

cv1800_mbox_send_data() could be called even inside
devm_mbox_controller_register(), so this needs to be moved up.

I will fix it

> + return 0;
> +}
> +
> +static struct platform_driver cv1800_mbox_driver = {
> + .driver = {
> + .name = "cv1800-mbox",
> + .of_match_table = cv1800_mbox_of_match,
> + },
> + .probe = cv1800_mbox_probe,
> +};
> +
> +module_platform_driver(cv1800_mbox_driver);
> +
> +MODULE_DESCRIPTION("cv1800 mailbox driver");
> +MODULE_LICENSE("GPL");

Next message: Yosry Ahmed: "Re: [PATCH V8 1/2] cgroup/rstat: Avoid flushing if there is an ongoing overlapping flush"
Previous message: Steven Davis: "[PATCH v3] Capitalized "c" to "C" and changed "expect" to "expected""
In reply to: Samuel Holland: "Re: [PATCH v2 3/3] mailbox: sophgo: add mailbox driver for cv18x SoCs"
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