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From:   Baolin Wang <baolin.wang7@gmail.com>
Date:   Wed, 6 May 2020 21:29:24 +0800
Message-ID: <CADBw62pDp4NByqNJ+ryUdBUi7GsW3tD8_vSN7iRGekThw0Xo+Q@mail.gmail.com>
Subject: Re: [PATCH v4 2/2] mailbox: sprd: Add Spreadtrum mailbox driver
To:     Rob Herring <robh+dt@kernel.org>,
        Jassi Brar <jassisinghbrar@gmail.com>
Cc:     Orson Zhai <orsonzhai@gmail.com>,
        Chunyan Zhang <zhang.lyra@gmail.com>,
        Devicetree List <devicetree@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Jassi,

On Tue, Apr 28, 2020 at 11:10 AM Baolin Wang <baolin.wang7@gmail.com> wrote:
>
> From: Baolin Wang <baolin.wang@unisoc.com>
>
> The Spreadtrum mailbox controller supports 8 channels to communicate
> with MCUs, and it contains 2 different parts: inbox and outbox, which
> are used to send and receive messages by IRQ mode.
>
> Signed-off-by: Baolin Wang <baolin.wang@unisoc.com>
> Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
> ---
> Changes from v3:
>  - Save the id in mbox_chan.con_priv and remove the 'sprd_mbox_chan'
>
> Changes from v2:
>  - None.
>
> Changes from v1:
>  - None

Gentle ping, do you have any other comments? Thanks.

> ---
>  drivers/mailbox/Kconfig        |   8 +
>  drivers/mailbox/Makefile       |   2 +
>  drivers/mailbox/sprd-mailbox.c | 341 +++++++++++++++++++++++++++++++++
>  3 files changed, 351 insertions(+)
>  create mode 100644 drivers/mailbox/sprd-mailbox.c
>
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 5a577a6734cf..e03f3fb5caed 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -236,4 +236,12 @@ config SUN6I_MSGBOX
>           various Allwinner SoCs. This mailbox is used for communication
>           between the application CPUs and the power management coprocessor.
>
> +config SPRD_MBOX
> +       tristate "Spreadtrum Mailbox"
> +       depends on ARCH_SPRD || COMPILE_TEST
> +       help
> +         Mailbox driver implementation for the Spreadtrum platform. It is used
> +         to send message between application processors and MCU. Say Y here if
> +         you want to build the Spreatrum mailbox controller driver.
> +
>  endif
> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> index 2e4364ef5c47..9caf4ede6ce0 100644
> --- a/drivers/mailbox/Makefile
> +++ b/drivers/mailbox/Makefile
> @@ -50,3 +50,5 @@ obj-$(CONFIG_MTK_CMDQ_MBOX)   += mtk-cmdq-mailbox.o
>  obj-$(CONFIG_ZYNQMP_IPI_MBOX)  += zynqmp-ipi-mailbox.o
>
>  obj-$(CONFIG_SUN6I_MSGBOX)     += sun6i-msgbox.o
> +
> +obj-$(CONFIG_SPRD_MBOX)                += sprd-mailbox.o
> diff --git a/drivers/mailbox/sprd-mailbox.c b/drivers/mailbox/sprd-mailbox.c
> new file mode 100644
> index 000000000000..f2c04984858a
> --- /dev/null
> +++ b/drivers/mailbox/sprd-mailbox.c
> @@ -0,0 +1,341 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Spreadtrum mailbox driver
> + *
> + * Copyright (c) 2020 Spreadtrum Communications Inc.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/mailbox_controller.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/clk.h>
> +
> +#define SPRD_MBOX_ID           0x0
> +#define SPRD_MBOX_MSG_LOW      0x4
> +#define SPRD_MBOX_MSG_HIGH     0x8
> +#define SPRD_MBOX_TRIGGER      0xc
> +#define SPRD_MBOX_FIFO_RST     0x10
> +#define SPRD_MBOX_FIFO_STS     0x14
> +#define SPRD_MBOX_IRQ_STS      0x18
> +#define SPRD_MBOX_IRQ_MSK      0x1c
> +#define SPRD_MBOX_LOCK         0x20
> +#define SPRD_MBOX_FIFO_DEPTH   0x24
> +
> +/* Bit and mask definiation for inbox's SPRD_MBOX_FIFO_STS register */
> +#define SPRD_INBOX_FIFO_DELIVER_MASK           GENMASK(23, 16)
> +#define SPRD_INBOX_FIFO_OVERLOW_MASK           GENMASK(15, 8)
> +#define SPRD_INBOX_FIFO_DELIVER_SHIFT          16
> +#define SPRD_INBOX_FIFO_BUSY_MASK              GENMASK(7, 0)
> +
> +/* Bit and mask definiation for SPRD_MBOX_IRQ_STS register */
> +#define SPRD_MBOX_IRQ_CLR                      BIT(0)
> +
> +/* Bit and mask definiation for outbox's SPRD_MBOX_FIFO_STS register */
> +#define SPRD_OUTBOX_FIFO_FULL                  BIT(0)
> +#define SPRD_OUTBOX_FIFO_WR_SHIFT              16
> +#define SPRD_OUTBOX_FIFO_RD_SHIFT              24
> +#define SPRD_OUTBOX_FIFO_POS_MASK              GENMASK(7, 0)
> +
> +/* Bit and mask definiation for inbox's SPRD_MBOX_IRQ_MSK register */
> +#define SPRD_INBOX_FIFO_BLOCK_IRQ              BIT(0)
> +#define SPRD_INBOX_FIFO_OVERFLOW_IRQ           BIT(1)
> +#define SPRD_INBOX_FIFO_DELIVER_IRQ            BIT(2)
> +#define SPRD_INBOX_FIFO_IRQ_MASK               GENMASK(2, 0)
> +
> +/* Bit and mask definiation for outbox's SPRD_MBOX_IRQ_MSK register */
> +#define SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ         BIT(0)
> +#define SPRD_OUTBOX_FIFO_IRQ_MASK              GENMASK(4, 0)
> +
> +#define SPRD_MBOX_CHAN_MAX                     8
> +
> +struct sprd_mbox_priv {
> +       struct mbox_controller  mbox;
> +       struct device           *dev;
> +       void __iomem            *inbox_base;
> +       void __iomem            *outbox_base;
> +       struct clk              *clk;
> +       u32                     outbox_fifo_depth;
> +
> +       struct mbox_chan        chan[SPRD_MBOX_CHAN_MAX];
> +};
> +
> +static struct sprd_mbox_priv *to_sprd_mbox_priv(struct mbox_controller *mbox)
> +{
> +       return container_of(mbox, struct sprd_mbox_priv, mbox);
> +}
> +
> +static u32 sprd_mbox_get_fifo_len(struct sprd_mbox_priv *priv, u32 fifo_sts)
> +{
> +       u32 wr_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_WR_SHIFT) &
> +               SPRD_OUTBOX_FIFO_POS_MASK;
> +       u32 rd_pos = (fifo_sts >> SPRD_OUTBOX_FIFO_RD_SHIFT) &
> +               SPRD_OUTBOX_FIFO_POS_MASK;
> +       u32 fifo_len;
> +
> +       /*
> +        * If the read pointer is equal with write pointer, which means the fifo
> +        * is full or empty.
> +        */
> +       if (wr_pos == rd_pos) {
> +               if (fifo_sts & SPRD_OUTBOX_FIFO_FULL)
> +                       fifo_len = priv->outbox_fifo_depth;
> +               else
> +                       fifo_len = 0;
> +       } else if (wr_pos > rd_pos) {
> +               fifo_len = wr_pos - rd_pos;
> +       } else {
> +               fifo_len = priv->outbox_fifo_depth - rd_pos + wr_pos;
> +       }
> +
> +       return fifo_len;
> +}
> +
> +static irqreturn_t sprd_mbox_outbox_isr(int irq, void *data)
> +{
> +       struct sprd_mbox_priv *priv = data;
> +       struct mbox_chan *chan;
> +       u32 fifo_sts, fifo_len, msg[2];
> +       int i, id;
> +
> +       fifo_sts = readl(priv->outbox_base + SPRD_MBOX_FIFO_STS);
> +
> +       fifo_len = sprd_mbox_get_fifo_len(priv, fifo_sts);
> +       if (!fifo_len) {
> +               dev_warn_ratelimited(priv->dev, "spurious outbox interrupt\n");
> +               return IRQ_NONE;
> +       }
> +
> +       for (i = 0; i < fifo_len; i++) {
> +               msg[0] = readl(priv->outbox_base + SPRD_MBOX_MSG_LOW);
> +               msg[1] = readl(priv->outbox_base + SPRD_MBOX_MSG_HIGH);
> +               id = readl(priv->outbox_base + SPRD_MBOX_ID);
> +
> +               chan = &priv->chan[id];
> +               mbox_chan_received_data(chan, (void *)msg);
> +
> +               /* Trigger to update outbox FIFO pointer */
> +               writel(0x1, priv->outbox_base + SPRD_MBOX_TRIGGER);
> +       }
> +
> +       /* Clear irq status after reading all message. */
> +       writel(SPRD_MBOX_IRQ_CLR, priv->outbox_base + SPRD_MBOX_IRQ_STS);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t sprd_mbox_inbox_isr(int irq, void *data)
> +{
> +       struct sprd_mbox_priv *priv = data;
> +       struct mbox_chan *chan;
> +       u32 fifo_sts, send_sts, id;
> +
> +       fifo_sts = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS);
> +
> +       /* Get the inbox data delivery status */
> +       send_sts = (fifo_sts & SPRD_INBOX_FIFO_DELIVER_MASK) >>
> +               SPRD_INBOX_FIFO_DELIVER_SHIFT;
> +       if (!send_sts) {
> +               dev_warn_ratelimited(priv->dev, "spurious inbox interrupt\n");
> +               return IRQ_NONE;
> +       }
> +
> +       while (send_sts) {
> +               id = __ffs(send_sts);
> +               send_sts &= (send_sts - 1);
> +
> +               chan = &priv->chan[id];
> +               mbox_chan_txdone(chan, 0);
> +       }
> +
> +       /* Clear FIFO delivery and overflow status */
> +       writel(fifo_sts &
> +              (SPRD_INBOX_FIFO_DELIVER_MASK | SPRD_INBOX_FIFO_OVERLOW_MASK),
> +              priv->inbox_base + SPRD_MBOX_FIFO_RST);
> +
> +       /* Clear irq status */
> +       writel(SPRD_MBOX_IRQ_CLR, priv->inbox_base + SPRD_MBOX_IRQ_STS);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +static int sprd_mbox_send_data(struct mbox_chan *chan, void *msg)
> +{
> +       struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
> +       unsigned long id = (unsigned long)chan->con_priv;
> +       u32 *data = msg, busy;
> +
> +       /*
> +        * Check if current channel is busy or not, and we can not send data
> +        * if current channel is busy.
> +        */
> +       busy = readl(priv->inbox_base + SPRD_MBOX_FIFO_STS) &
> +               SPRD_INBOX_FIFO_BUSY_MASK;
> +       if (busy & BIT(id)) {
> +               dev_err(priv->dev, "Channel %ld is busy\n", id);
> +               return -EBUSY;
> +       }
> +
> +       /* Write data into inbox FIFO, and only support 8 bytes every time */
> +       writel(data[0], priv->inbox_base + SPRD_MBOX_MSG_LOW);
> +       writel(data[1], priv->inbox_base + SPRD_MBOX_MSG_HIGH);
> +
> +       /* Set target core id */
> +       writel(id, priv->inbox_base + SPRD_MBOX_ID);
> +
> +       /* Trigger remote request */
> +       writel(0x1, priv->inbox_base + SPRD_MBOX_TRIGGER);
> +
> +       return 0;
> +}
> +
> +static int sprd_mbox_startup(struct mbox_chan *chan)
> +{
> +       struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
> +       u32 val;
> +
> +       /* Select outbox FIFO mode and reset the outbox FIFO status */
> +       writel(0x0, priv->outbox_base + SPRD_MBOX_FIFO_RST);
> +
> +       /* Enable inbox FIFO overflow and delivery interrupt */
> +       val = readl(priv->inbox_base + SPRD_MBOX_IRQ_MSK);
> +       val &= ~(SPRD_INBOX_FIFO_OVERFLOW_IRQ | SPRD_INBOX_FIFO_DELIVER_IRQ);
> +       writel(val, priv->inbox_base + SPRD_MBOX_IRQ_MSK);
> +
> +       /* Enable outbox FIFO not empty interrupt */
> +       val = readl(priv->outbox_base + SPRD_MBOX_IRQ_MSK);
> +       val &= ~SPRD_OUTBOX_FIFO_NOT_EMPTY_IRQ;
> +       writel(val, priv->outbox_base + SPRD_MBOX_IRQ_MSK);
> +
> +       return 0;
> +}
> +
> +static void sprd_mbox_shutdown(struct mbox_chan *chan)
> +{
> +       struct sprd_mbox_priv *priv = to_sprd_mbox_priv(chan->mbox);
> +
> +       /* Disable inbox & outbox interrupt */
> +       writel(SPRD_INBOX_FIFO_IRQ_MASK, priv->inbox_base + SPRD_MBOX_IRQ_MSK);
> +       writel(SPRD_OUTBOX_FIFO_IRQ_MASK, priv->outbox_base + SPRD_MBOX_IRQ_MSK);
> +}
> +
> +static const struct mbox_chan_ops sprd_mbox_ops = {
> +       .send_data    = sprd_mbox_send_data,
> +       .startup      = sprd_mbox_startup,
> +       .shutdown     = sprd_mbox_shutdown,
> +};
> +
> +static void sprd_mbox_disable(void *data)
> +{
> +       struct sprd_mbox_priv *priv = data;
> +
> +       clk_disable_unprepare(priv->clk);
> +}
> +
> +static int sprd_mbox_probe(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct sprd_mbox_priv *priv;
> +       int ret, inbox_irq, outbox_irq;
> +       unsigned long id;
> +
> +       priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
> +       if (!priv)
> +               return -ENOMEM;
> +
> +       priv->dev = dev;
> +
> +       /*
> +        * The Spreadtrum mailbox uses an inbox to send messages to the target
> +        * core, and uses an outbox to receive messages from other cores.
> +        *
> +        * Thus the mailbox controller supplies 2 different register addresses
> +        * and IRQ numbers for inbox and outbox.
> +        */
> +       priv->inbox_base = devm_platform_ioremap_resource(pdev, 0);
> +       if (IS_ERR(priv->inbox_base))
> +               return PTR_ERR(priv->inbox_base);
> +
> +       priv->outbox_base = devm_platform_ioremap_resource(pdev, 1);
> +       if (IS_ERR(priv->outbox_base))
> +               return PTR_ERR(priv->outbox_base);
> +
> +       priv->clk = devm_clk_get(dev, "enable");
> +       if (IS_ERR(priv->clk)) {
> +               dev_err(dev, "failed to get mailbox clock\n");
> +               return PTR_ERR(priv->clk);
> +       }
> +
> +       ret = clk_prepare_enable(priv->clk);
> +       if (ret)
> +               return ret;
> +
> +       ret = devm_add_action_or_reset(dev, sprd_mbox_disable, priv);
> +       if (ret) {
> +               dev_err(dev, "failed to add mailbox disable action\n");
> +               return ret;
> +       }
> +
> +       inbox_irq = platform_get_irq(pdev, 0);
> +       if (inbox_irq < 0)
> +               return inbox_irq;
> +
> +       ret = devm_request_irq(dev, inbox_irq, sprd_mbox_inbox_isr,
> +                              IRQF_NO_SUSPEND, dev_name(dev), priv);
> +       if (ret) {
> +               dev_err(dev, "failed to request inbox IRQ: %d\n", ret);
> +               return ret;
> +       }
> +
> +       outbox_irq = platform_get_irq(pdev, 1);
> +       if (outbox_irq < 0)
> +               return outbox_irq;
> +
> +       ret = devm_request_irq(dev, outbox_irq, sprd_mbox_outbox_isr,
> +                              IRQF_NO_SUSPEND, dev_name(dev), priv);
> +       if (ret) {
> +               dev_err(dev, "failed to request outbox IRQ: %d\n", ret);
> +               return ret;
> +       }
> +
> +       /* Get the default outbox FIFO depth */
> +       priv->outbox_fifo_depth =
> +               readl(priv->outbox_base + SPRD_MBOX_FIFO_DEPTH) + 1;
> +       priv->mbox.dev = dev;
> +       priv->mbox.chans = &priv->chan[0];
> +       priv->mbox.num_chans = SPRD_MBOX_CHAN_MAX;
> +       priv->mbox.ops = &sprd_mbox_ops;
> +       priv->mbox.txdone_irq = true;
> +
> +       for (id = 0; id < SPRD_MBOX_CHAN_MAX; id++)
> +               priv->chan[id].con_priv = (void *)id;
> +
> +       ret = devm_mbox_controller_register(dev, &priv->mbox);
> +       if (ret) {
> +               dev_err(dev, "failed to register mailbox: %d\n", ret);
> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +
> +static const struct of_device_id sprd_mbox_of_match[] = {
> +       { .compatible = "sprd,sc9860-mailbox", },
> +       { },
> +};
> +MODULE_DEVICE_TABLE(of, sprd_mbox_of_match);
> +
> +static struct platform_driver sprd_mbox_driver = {
> +       .driver = {
> +               .name = "sprd-mailbox",
> +               .of_match_table = sprd_mbox_of_match,
> +       },
> +       .probe  = sprd_mbox_probe,
> +};
> +module_platform_driver(sprd_mbox_driver);
> +
> +MODULE_AUTHOR("Baolin Wang <baolin.wang@unisoc.com>");
> +MODULE_DESCRIPTION("Spreadtrum mailbox driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.17.1
>


-- 
Baolin Wang