[4/6] soc: add polarfire soc system controller

From: Conor Dooley <conor.dooley@microchip.com>

This driver provides an interface for other drivers to access the
functions of the system controller on the Microchip PolarFire SoC.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
---
 drivers/soc/Kconfig                         |   1 +
 drivers/soc/Makefile                        |   1 +
 drivers/soc/microchip/Kconfig               |  10 ++
 drivers/soc/microchip/Makefile              |   1 +
 drivers/soc/microchip/mpfs_sys_controller.c | 136 ++++++++++++++++++++
 5 files changed, 149 insertions(+)
 create mode 100644 drivers/soc/microchip/Kconfig
 create mode 100644 drivers/soc/microchip/Makefile
 create mode 100644 drivers/soc/microchip/mpfs_sys_controller.c

On 2020/11/20 2:05, conor.dooley@microchip.com wrote:
> From: Conor Dooley <conor.dooley@microchip.com>
> 
> This driver provides an interface for other drivers to access the
> functions of the system controller on the Microchip PolarFire SoC.
> 
> Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
> ---
>  drivers/soc/Kconfig                         |   1 +
>  drivers/soc/Makefile                        |   1 +
>  drivers/soc/microchip/Kconfig               |  10 ++
>  drivers/soc/microchip/Makefile              |   1 +
>  drivers/soc/microchip/mpfs_sys_controller.c | 136 ++++++++++++++++++++
>  5 files changed, 149 insertions(+)
>  create mode 100644 drivers/soc/microchip/Kconfig
>  create mode 100644 drivers/soc/microchip/Makefile
>  create mode 100644 drivers/soc/microchip/mpfs_sys_controller.c
> 
> diff --git a/drivers/soc/Kconfig b/drivers/soc/Kconfig
> index 425ab6f7e375..22cb097bcbdc 100644
> --- a/drivers/soc/Kconfig
> +++ b/drivers/soc/Kconfig
> @@ -9,6 +9,7 @@ source "drivers/soc/bcm/Kconfig"
>  source "drivers/soc/fsl/Kconfig"
>  source "drivers/soc/imx/Kconfig"
>  source "drivers/soc/ixp4xx/Kconfig"
> +source "drivers/soc/microchip/Kconfig"
>  source "drivers/soc/mediatek/Kconfig"
>  source "drivers/soc/qcom/Kconfig"
>  source "drivers/soc/renesas/Kconfig"
> diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
> index 36452bed86ef..fb084cf2d12e 100644
> --- a/drivers/soc/Makefile
> +++ b/drivers/soc/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_ARCH_GEMINI)	+= gemini/
>  obj-y				+= imx/
>  obj-$(CONFIG_ARCH_IXP4XX)	+= ixp4xx/
>  obj-$(CONFIG_SOC_XWAY)		+= lantiq/
> +obj-$(CONFIG_SOC_MICROCHIP_POLARFIRE)	+= microchip/
>  obj-y				+= mediatek/
>  obj-y				+= amlogic/
>  obj-y				+= qcom/
> diff --git a/drivers/soc/microchip/Kconfig b/drivers/soc/microchip/Kconfig
> new file mode 100644
> index 000000000000..8fdba8b5eae3
> --- /dev/null
> +++ b/drivers/soc/microchip/Kconfig
> @@ -0,0 +1,10 @@
> +config MPFS_SYS_CONTROLLER
> +	tristate "MPFS_SYS_CONTROLLER"
> +	depends on MPFS_MBOX
> +	help
> +	  This driver adds support for the Polarfire SoC system controller.
> +
> +	  To compile this driver as a module, choose M here. the
> +	  module will be called mpfs_system_controller.
> +
> +	  If unsure, say Y.

Say Y if unsure ? If someone is unsure they are using a polarfire, they I would
say all hope is lost, so "say N" sound like a better idea to avoid compiling
unnecessary drivers...

> diff --git a/drivers/soc/microchip/Makefile b/drivers/soc/microchip/Makefile
> new file mode 100644
> index 000000000000..23b1f42a37db
> --- /dev/null
> +++ b/drivers/soc/microchip/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_MPFS_SYS_CONTROLLER)	+= mpfs_sys_controller.o
> diff --git a/drivers/soc/microchip/mpfs_sys_controller.c b/drivers/soc/microchip/mpfs_sys_controller.c
> new file mode 100644
> index 000000000000..0074ae529a2e
> --- /dev/null
> +++ b/drivers/soc/microchip/mpfs_sys_controller.c
> @@ -0,0 +1,136 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Microchip MPFS system controller driver
> + *
> + * Copyright (c) 2020 Microchip Corporation. All rights reserved.
> + *
> + * Author: Conor Dooley <conor.dooley@microchip.com>
> + *
> + */
> +
> +#include <linux/slab.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/of_platform.h>
> +#include <linux/mailbox_client.h>
> +#include <linux/platform_device.h>
> +#include <soc/microchip/mpfs.h>
> +
> +static DEFINE_MUTEX(transaction_lock);
> +
> +struct mpfs_sys_controller {
> +	struct mbox_client client;
> +	struct mbox_chan *chan;
> +	struct completion c;
> +	u32 enabled;
> +	void *response;
> +	u16 response_size_bytes;
> +};
> +
> +int mpfs_blocking_transaction(struct mpfs_sys_controller *mpfs_client, void *msg,
> +			      void *response, u16 response_size_bytes)
> +{
> +	int ret;
> +
> +	mpfs_client->response = response;
> +	mpfs_client->response_size_bytes = response_size_bytes;
> +
> +	mutex_lock_interruptible(&transaction_lock);
> +
> +	reinit_completion(&mpfs_client->c);
> +
> +	ret = mbox_send_message(mpfs_client->chan, msg);
> +

No need for this empty line.

> +	if (ret >= 0U) {

Please stop with the 0u and 0U... Just use "0".

> +		if (wait_for_completion_timeout(&mpfs_client->c, HZ)) {
> +			ret = 0U;
> +		} else {
> +			ret = -ETIMEDOUT;
> +			WARN_ONCE(1, "MPFS sys controller transaction timeout");

Why not dev_warn() ?

> +		}
> +	} else {
> +		dev_err(mpfs_client->client.dev,
> +			"mpfs sys controller transaction returned %d\r\n", ret);
> +	}
> +
> +	mutex_unlock(&transaction_lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(mpfs_blocking_transaction);
> +
> +static void rx_callback(struct mbox_client *client, void *msg)
> +{
> +	struct mpfs_sys_controller *mpfs_client =
> +		container_of(client, struct mpfs_sys_controller, client);
> +
> +	memcpy(mpfs_client->response, (u8 *)msg,
> +	       mpfs_client->response_size_bytes);
> +
> +	complete(&mpfs_client->c);
> +}
> +
> +static int mpfs_sys_controller_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct mpfs_sys_controller *mpfs_client;
> +
> +	mpfs_client = devm_kzalloc(dev, sizeof(*mpfs_client), GFP_KERNEL);
> +	if (!mpfs_client)
> +		return -ENOMEM;
> +
> +	mpfs_client->client.dev = dev;
> +	mpfs_client->client.rx_callback = rx_callback;
> +	mpfs_client->client.tx_block = 1U;
> +
> +	mpfs_client->chan = mbox_request_channel_byname(&mpfs_client->client,
> +							"mbox-mpfs");
> +	if (IS_ERR(mpfs_client->chan)) {
> +		int ret = PTR_ERR(mpfs_client->chan);
> +
> +		if (ret != -EPROBE_DEFER)
> +			dev_err(dev, "Failed to get mbox channel: %d\n", ret);
> +		return ret;
> +	}
> +
> +	init_completion(&mpfs_client->c);
> +
> +	platform_set_drvdata(pdev, mpfs_client);
> +
> +	dev_info(&pdev->dev, "Registered MPFS system controller driver\n");
> +
> +	return 0;
> +}
> +
> +struct mpfs_sys_controller *
> +mpfs_sys_controller_get(struct device_node *mss_node)
> +{
> +	struct platform_device *pdev = of_find_device_by_node(mss_node);
> +
> +	if (!pdev)
> +		return NULL;
> +
> +	return platform_get_drvdata(pdev);
> +}
> +EXPORT_SYMBOL(mpfs_sys_controller_get);
> +
> +static const struct of_device_id mpfs_sys_controller_of_match[] = {
> +	{
> +		.compatible = "microchip,polarfire-soc-sys-controller",
> +	},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, mpfs_sys_controller_of_match);
> +
> +static struct platform_driver mpfs_sys_controller_driver = {
> +	.driver = {
> +		.name = "mpfs-sys-controller",
> +		.of_match_table = mpfs_sys_controller_of_match,
> +	},
> +	.probe = mpfs_sys_controller_probe,
> +};
> +module_platform_driver(mpfs_sys_controller_driver);
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
> +MODULE_DESCRIPTION("MPFS system controller driver");
>