[PATCH v2 1/5] mbox: add polarfire soc system controller mailbox

[Damien Le Moal]

On 2020/12/01 20:02, conor.dooley at microchip.com wrote:
> From: Conor Dooley <conor.dooley at microchip.com>
> 
> This driver adds support for the single mailbox channel of the MSS
> system controller on the Microchip PolarFire SoC.
> 
> Signed-off-by: Conor Dooley <conor.dooley at microchip.com>
> ---
>  drivers/mailbox/Kconfig        |  12 ++
>  drivers/mailbox/Makefile       |   2 +
>  drivers/mailbox/mailbox-mpfs.c | 285 +++++++++++++++++++++++++++++++++
>  include/soc/microchip/mpfs.h   |  51 ++++++
>  4 files changed, 350 insertions(+)
>  create mode 100644 drivers/mailbox/mailbox-mpfs.c
>  create mode 100644 include/soc/microchip/mpfs.h
> 
> diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> index 05b1009e2820..fbf6902c3541 100644
> --- a/drivers/mailbox/Kconfig
> +++ b/drivers/mailbox/Kconfig
> @@ -153,6 +153,18 @@ config MAILBOX_TEST
>  	  Test client to help with testing new Controller driver
>  	  implementations.
>  
> +config MPFS_MBOX
> +	tristate "MPFS Mailbox"
> +	depends on HAS_IOMEM
> +	depends on SOC_MICROCHIP_POLARFIRE || COMPILE_TEST
> +	help
> +	  This driver adds support for the Polarfire SoC mailbox controller.
> +
> +	  To compile this driver as a module, choose M here. the
> +	  module will be called mailbox-mpfs.
> +
> +	  If unsure, say N.
> +
>  config QCOM_APCS_IPC
>  	tristate "Qualcomm APCS IPC driver"
>  	depends on ARCH_QCOM || COMPILE_TEST
> diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> index 2e06e02b2e03..63f49b5bcc43 100644
> --- a/drivers/mailbox/Makefile
> +++ b/drivers/mailbox/Makefile
> @@ -39,6 +39,8 @@ obj-$(CONFIG_BCM_PDC_MBOX)	+= bcm-pdc-mailbox.o
>  
>  obj-$(CONFIG_BCM_FLEXRM_MBOX)	+= bcm-flexrm-mailbox.o
>  
> +obj-$(CONFIG_MPFS_MBOX)	+= mailbox-mpfs.o
> +
>  obj-$(CONFIG_QCOM_APCS_IPC)	+= qcom-apcs-ipc-mailbox.o
>  
>  obj-$(CONFIG_TEGRA_HSP_MBOX)	+= tegra-hsp.o
> diff --git a/drivers/mailbox/mailbox-mpfs.c b/drivers/mailbox/mailbox-mpfs.c
> new file mode 100644
> index 000000000000..e1ecf3081312
> --- /dev/null
> +++ b/drivers/mailbox/mailbox-mpfs.c
> @@ -0,0 +1,285 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Microchip MPFS system controller/mailbox controller driver
> + *
> + * Copyright (c) 2020 Microchip Corporation. All rights reserved.
> + *
> + * Author: Conor Dooley <conor.dooley at microchip.com>
> + *
> + */
> +
> +#include <linux/io.h>
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/mailbox_controller.h>
> +#include <soc/microchip/mpfs.h>
> +
> +#define SERVICES_CR_OFFSET		0x50u
> +#define SERVICES_SR_OFFSET		0x54u
> +#define MAILBOX_REG_OFFSET		0x800u
> +#define MSS_SYS_BUSY			-EBUSY
> +#define MSS_SYS_PARAM_ERR		-EINVAL
> +#define MSS_SYS_MAILBOX_DATA_OFFSET	0u
> +#define SCB_MASK_WIDTH 			16u

Value identation seems off here. Aligning it would be nice.

> +/* SCBCTRL service control register */
> +
> +#define SCB_CTRL_REQ (0u)
> +#define SCB_CTRL_REQ_MASK BIT(SCB_CTRL_REQ)
> +
> +#define SCB_CTRL_BUSY (1u)
> +#define SCB_CTRL_BUSY_MASK BIT(SCB_CTRL_BUSY)
> +
> +#define SCB_CTRL_ABORT (2u)
> +#define SCB_CTRL_ABORT_MASK BIT(SCB_CTRL_ABORT)
> +
> +#define SCB_CTRL_NOTIFY (3u)
> +#define SCB_CTRL_NOTIFY_MASK BIT(SCB_CTRL_NOTIFY)
> +
> +#define SCB_CTRL_POS (16u)
> +#define SCB_CTRL_MASK GENMASK(SCB_CTRL_POS+SCB_MASK_WIDTH, SCB_CTRL_POS)

Please add spaces before and after the "+" operator.

And I am really not a big fan of the (useless in my opinion) "u" for unsigned
for all of these.

> +
> +/* SCBCTRL service status registers */
> +
> +#define SCB_STATUS_REQ (0u)
> +#define SCB_STATUS_REQ_MASK BIT(SCB_STATUS_REQ)
> +
> +#define SCB_STATUS_BUSY (1u)
> +#define SCB_STATUS_BUSY_MASK BIT(SCB_STATUS_BUSY)
> +
> +#define SCB_STATUS_ABORT (2u)
> +#define SCB_STATUS_ABORT_MASK BIT(SCB_STATUS_ABORT)
> +
> +#define SCB_STATUS_NOTIFY (3u)
> +#define SCB_STATUS_NOTIFY_MASK BIT(SCB_STATUS_NOTIFY)
> +
> +#define SCB_STATUS_POS (16u)
> +#define SCB_STATUS_MASK GENMASK(SCB_STATUS_POS+SCB_MASK_WIDTH, SCB_STATUS_POS)

Spaces around "+".

> +
> +struct mpfs_mbox {
> +	struct mbox_controller controller;
> +	struct device *dev;
> +	int irq;
> +	void __iomem *mailbox_base;
> +	void __iomem *int_reg;
> +	struct mbox_chan *chan;
> +	u16 response_size;
> +	u16 response_offset;
> +};
> +
> +static bool mpfs_mbox_busy(struct mpfs_mbox *mbox)
> +{
> +	u32 status;
> +
> +	status = readl_relaxed(mbox->mailbox_base + SERVICES_SR_OFFSET);
> +
> +	return status & SCB_STATUS_BUSY_MASK;
> +}
> +
> +static struct mpfs_mbox *mbox_chan_to_mpfs_mbox(struct mbox_chan *chan)
> +{
> +	if (!chan || !chan->con_priv)
> +		return NULL;

You do not need the "|| !chan->con_priv" here. The return below will return NULL.

> +
> +	return (struct mpfs_mbox *)chan->con_priv;
> +}
> +
> +static int mpfs_mbox_send_data(struct mbox_chan *chan, void *data)
> +{
> +	u32 index;
> +	u32 *word_buf;
> +	u8 *byte_buf;
> +	u8 byte_off;
> +	u8 i;
> +	u32 mailbox_val = 0u;
> +	u16 mb_offset;
> +	u16 mbox_options_select;
> +	u32 mbox_tx_trigger;
> +	struct mpfs_mss_msg *msg = data;
> +	struct mpfs_mbox *mbox = mbox_chan_to_mpfs_mbox(chan);
> +	mb_offset = msg->mailbox_offset;
> +	mbox->response_size = msg->response_size;
> +	mbox->response_offset = msg->response_offset;
> +
> +	if (mpfs_mbox_busy(mbox))
> +		return MSS_SYS_BUSY;
> +
> +	mbox_options_select = ((mb_offset << 7u) | (msg->cmd_opcode & 0x7fu));
> +	mbox_tx_trigger = (((mbox_options_select << SCB_CTRL_POS) &
> +		SCB_CTRL_MASK) | SCB_CTRL_REQ_MASK | SCB_STATUS_NOTIFY_MASK);
> +
> +	/* Code for MSS_SYS_PARAM_ERR is not implemented with this version of driver. */
> +
> +	writel_relaxed(0x0u, mbox->int_reg);

0x0u seems like an awfully complicated way of writing 0. Less characters for the
brain to decode makes reading easier :)

> +
> +	if (msg->cmd_data_size) {
> +		byte_buf = (u8 *)(msg->cmd_data);
> +
> +		for (index = 0; index < (msg->cmd_data_size / 4); index++) {
> +			writel_relaxed(word_buf[index],
> +				       mbox->mailbox_base + MAILBOX_REG_OFFSET + index);
> +		}

You do not need the braces here.

> +
> +		if ((msg->cmd_data_size % 4) > 0) {

s/% 4/& 3. And you do not need the "> 0".

> +			byte_off = (((msg->cmd_data_size / 4) * 4));

Extra outside parenthesis not needed.
byte_off = msg->cmd_data_size & (~3);
or
byte_off = ALIGN_DOWN(msg->cmd_data_size, 4);

> +			byte_buf = (u8 *)(msg->cmd_data + byte_off);

cmd_data is already u8 *, so you do not need the cast.

> +
> +			mailbox_val = readl_relaxed(mbox->mailbox_base +
> +					    MAILBOX_REG_OFFSET + index);
> +
> +			for (i = 0u; i < (msg->cmd_data_size % 4u); i++) {

% 4 -> & 3
And since you already have taht in the if above, why not use a local variable ?

> +				mailbox_val &= ~(0xffu << (i * 8u));
> +				mailbox_val |= (byte_buf[i] << (i * 8u));
> +			}
> +
> +			writel_relaxed(mailbox_val, mbox->mailbox_base + MAILBOX_REG_OFFSET + index);
> +		}
> +	}
> +
> +	writel_relaxed(mbox_tx_trigger, mbox->mailbox_base + SERVICES_CR_OFFSET);
> +
> +	return 0;
> +}
> +
> +static inline bool mpfs_mbox_pending(struct mpfs_mbox *mbox)
> +{
> +	u32 status;
> +
> +	status = readl_relaxed(mbox->mailbox_base + SERVICES_SR_OFFSET);
> +
> +	return !(status & SCB_STATUS_BUSY_MASK);
> +}
> +
> +static void mpfs_mbox_rx_data(struct mbox_chan *chan)
> +{
> +	struct mpfs_mbox *mbox = mbox_chan_to_mpfs_mbox(chan);
> +	u32 *data;
> +	u32 i;
> +	u32 response_limit;
> +
> +	data = devm_kzalloc(mbox->dev, sizeof(*data) * mbox->response_size, GFP_ATOMIC);
> +	if (!data)
> +		dev_err(mbox->dev, "failed to register mailbox interrupt:%d\n", -ENOMEM);
> +
> +	response_limit = (mbox->response_size) + (mbox->response_offset);
> +	if (mpfs_mbox_pending(mbox) && mbox->response_size > 0U) {
> +		for (i = (mbox->response_offset); i < response_limit; i++) {

Parenthesis not needed around (mbox->response_offset).

> +			data[i - (mbox->response_offset)] =

Same here.

> +				readl_relaxed(mbox->mailbox_base + MAILBOX_REG_OFFSET + i * 0x4);
> +		}
> +	}
> +
> +	mbox_chan_received_data(chan, (void *)data);
> +	devm_kfree(mbox->dev, data);
> +}
> +
> +static irqreturn_t mpfs_mbox_inbox_isr(int irq, void *data)
> +{
> +	struct mbox_chan *chan = (struct mbox_chan *)data;
> +	struct mpfs_mbox *mbox = mbox_chan_to_mpfs_mbox(chan);
> +
> +	writel_relaxed(0x0U, mbox->int_reg);

0x0U == 0...

> +
> +	mpfs_mbox_rx_data(chan);
> +
> +	mbox_chan_txdone(chan, 0);
> +	return IRQ_HANDLED;
> +}
> +
> +static int mpfs_mbox_startup(struct mbox_chan *chan)
> +{
> +	struct mpfs_mbox *mbox = mbox_chan_to_mpfs_mbox(chan);
> +	int ret = 0;
> +
> +	if (!mbox)
> +		return -EINVAL;
> +	ret = devm_request_irq(mbox->dev, mbox->irq, mpfs_mbox_inbox_isr, 0, "mpfs-mailbox", chan);
> +	if (ret) {
> +		dev_err(mbox->dev, "failed to register mailbox interrupt:%d\n", ret);
> +	}

No need for the curly braces.

> +
> +	return ret;
> +}
> +
> +static void mpfs_mbox_shutdown(struct mbox_chan *chan)
> +{
> +	struct mpfs_mbox *mbox = mbox_chan_to_mpfs_mbox(chan);
> +
> +	devm_free_irq(mbox->dev, mbox->irq, chan);
> +}
> +
> +static const struct mbox_chan_ops mpfs_mbox_ops = {
> +	.send_data = mpfs_mbox_send_data,
> +	.startup = mpfs_mbox_startup,
> +	.shutdown = mpfs_mbox_shutdown,
> +};
> +
> +static int mpfs_mbox_probe(struct platform_device *pdev)
> +{
> +	struct mpfs_mbox *mbox;
> +	struct resource *regs;
> +	struct mbox_chan *chans;
> +	int ret;
> +
> +	mbox = devm_kzalloc(&pdev->dev, sizeof(*mbox), GFP_KERNEL);
> +	if (!mbox)
> +		return -ENOMEM;
> +
> +	chans = devm_kzalloc(&pdev->dev, sizeof(*chans), GFP_KERNEL);
> +	if (!chans)
> +		return -ENOMEM;
> +
> +	mbox->mailbox_base = devm_platform_get_and_ioremap_resource(pdev, 0, &regs);
> +	if (IS_ERR(mbox->mailbox_base))
> +		return PTR_ERR(mbox->mailbox_base);
> +
> +	mbox->int_reg = devm_platform_get_and_ioremap_resource(pdev, 1, &regs);
> +	if (IS_ERR(mbox->int_reg))
> +		return PTR_ERR(mbox->int_reg);
> +
> +	mbox->irq = platform_get_irq(pdev, 0);
> +	if (mbox->irq < 0)
> +		return mbox->irq;
> +
> +	mbox->dev = &pdev->dev;
> +
> +	chans[0].con_priv = mbox;
> +	mbox->controller.dev = mbox->dev;
> +	mbox->controller.num_chans = 1;
> +	mbox->controller.chans = chans;
> +	mbox->controller.ops = &mpfs_mbox_ops;
> +	mbox->controller.txdone_irq = true;
> +
> +	ret = devm_mbox_controller_register(&pdev->dev, &mbox->controller);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Registering MPFS mailbox controller failed\n");
> +		return ret;
> +	}
> +	dev_info(&pdev->dev, "Registered MPFS mailbox controller driver\n");
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id mpfs_mbox_of_match[] = {
> +	{
> +		.compatible = "microchip,polarfire-soc-mailbox",
> +	},
> +	{},
> +};

The typical way of writing this is:

static const struct of_device_id mpfs_mbox_of_match[] = {
	{ .compatible = "microchip,polarfire-soc-mailbox", },
	{}
};


> +MODULE_DEVICE_TABLE(of, mpfs_mbox_of_match);
> +
> +static struct platform_driver mpfs_mbox_driver = {
> +	.driver = {
> +		.name = "mpfs-mailbox",
> +		.of_match_table = mpfs_mbox_of_match,
> +	},
> +	.probe = mpfs_mbox_probe,
> +};
> +module_platform_driver(mpfs_mbox_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Conor Dooley <conor.dooley at microchip.com>");
> +MODULE_DESCRIPTION("MPFS mailbox controller driver");
> diff --git a/include/soc/microchip/mpfs.h b/include/soc/microchip/mpfs.h
> new file mode 100644
> index 000000000000..b231f39f32eb
> --- /dev/null
> +++ b/include/soc/microchip/mpfs.h
> @@ -0,0 +1,51 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + *
> + * Microchip MPFS mailbox
> + *
> + * Copyright (c) 2020 Microchip Corporation. All rights reserved.
> + *
> + * Author: Conor Dooley <conor.dooley at microchip.com>
> + *
> + */
> +
> +#ifndef __SOC_MPFS_H__
> +#define __SOC_MPFS_H__
> +
> +#include <linux/types.h>
> +#include <linux/of_device.h>
> +
> +struct mpfs_sys_controller;
> +
> +struct mpfs_mss_msg {
> +	u8 cmd_opcode;
> +	u16 cmd_data_size;
> +	u16 response_size;
> +	u8 *cmd_data;
> +	u16 mailbox_offset;
> +	u16 response_offset;
> +};
> +
> +#if IS_ENABLED(CONFIG_MPFS_SYS_CONTROLLER)

A simple #ifdef would do.

> +
> +int mpfs_blocking_transaction(struct mpfs_sys_controller *mpfs_client, void *msg,
> +			      void *response, u16 response_size_bytes);
> +
> +struct mpfs_sys_controller *mpfs_sys_controller_get(struct device_node *mailbox_node);
> +
> +#else
> +
> +static int mpfs_blocking_transaction(struct mpfs_sys_controller *mpfs_client, void *msg,
> +				     void *response, u16 response_size_bytes)
> +{
> +	return -ENOSYS;
> +};
> +
> +struct mpfs_sys_controller *mpfs_sys_controller_get(struct device_node *mailbox_node)
> +{
> +	return NULL;
> +}
> +
> +#endif /* IS_ENABLED(CONFIG_MPFS_SYS_CONTROLLER) */
> +
> +#endif /* __SOC_MPFS_H__ */
> 
-- 
Damien Le Moal
Western Digital Research