[v1,3/3] power: reset: Add TPS65086 restart driver

The only way to reset the BeagleV Starlight v0.9 board[1] properly is to
tell the PMIC to reset itself which will then assert the external reset
lines of the SoC, USB hub and ethernet phy.

This adds a driver to register a reset handler to do just that.

[1] https://github.com/beagleboard/beaglev-starlight

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
---
 drivers/mfd/tps65086.c                 |  1 +
 drivers/power/reset/Kconfig            |  6 ++
 drivers/power/reset/Makefile           |  1 +
 drivers/power/reset/tps65086-restart.c | 99 ++++++++++++++++++++++++++
 4 files changed, 107 insertions(+)
 create mode 100644 drivers/power/reset/tps65086-restart.c

Hi,

On Sat, Jun 26, 2021 at 12:47:44AM +0200, Emil Renner Berthing wrote:
> The only way to reset the BeagleV Starlight v0.9 board[1] properly is to
> tell the PMIC to reset itself which will then assert the external reset
> lines of the SoC, USB hub and ethernet phy.
> 
> This adds a driver to register a reset handler to do just that.
> 
> [1] https://github.com/beagleboard/beaglev-starlight
> 
> Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> ---

Acked-by: Sebastian Reichel <sebastian.reichel@collabora.com>

-- Sebastian

>  drivers/mfd/tps65086.c                 |  1 +
>  drivers/power/reset/Kconfig            |  6 ++
>  drivers/power/reset/Makefile           |  1 +
>  drivers/power/reset/tps65086-restart.c | 99 ++++++++++++++++++++++++++
>  4 files changed, 107 insertions(+)
>  create mode 100644 drivers/power/reset/tps65086-restart.c
> 
> diff --git a/drivers/mfd/tps65086.c b/drivers/mfd/tps65086.c
> index cc3478ee9a64..1bfba0758fcc 100644
> --- a/drivers/mfd/tps65086.c
> +++ b/drivers/mfd/tps65086.c
> @@ -24,6 +24,7 @@
>  static const struct mfd_cell tps65086_cells[] = {
>  	{ .name = "tps65086-regulator", },
>  	{ .name = "tps65086-gpio", },
> +	{ .name = "tps65086-restart", },
>  };
>  
>  static const struct regmap_range tps65086_yes_ranges[] = {
> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> index 4d1192062508..4b563db3ab3e 100644
> --- a/drivers/power/reset/Kconfig
> +++ b/drivers/power/reset/Kconfig
> @@ -204,6 +204,12 @@ config POWER_RESET_ST
>  	help
>  	  Reset support for STMicroelectronics boards.
>  
> +config POWER_RESET_TPS65086
> +	bool "TPS65086 restart driver"
> +	depends on MFD_TPS65086
> +	help
> +	  This driver adds support for resetting the TPS65086 PMIC on restart.
> +
>  config POWER_RESET_VERSATILE
>  	bool "ARM Versatile family reboot driver"
>  	depends on ARM
> diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
> index cf3f4d02d8a5..f606a2f60539 100644
> --- a/drivers/power/reset/Makefile
> +++ b/drivers/power/reset/Makefile
> @@ -23,6 +23,7 @@ obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
>  obj-$(CONFIG_POWER_RESET_REGULATOR) += regulator-poweroff.o
>  obj-$(CONFIG_POWER_RESET_RESTART) += restart-poweroff.o
>  obj-$(CONFIG_POWER_RESET_ST) += st-poweroff.o
> +obj-$(CONFIG_POWER_RESET_TPS65086) += tps65086-restart.o
>  obj-$(CONFIG_POWER_RESET_VERSATILE) += arm-versatile-reboot.o
>  obj-$(CONFIG_POWER_RESET_VEXPRESS) += vexpress-poweroff.o
>  obj-$(CONFIG_POWER_RESET_XGENE) += xgene-reboot.o
> diff --git a/drivers/power/reset/tps65086-restart.c b/drivers/power/reset/tps65086-restart.c
> new file mode 100644
> index 000000000000..ad9f2c5a84ac
> --- /dev/null
> +++ b/drivers/power/reset/tps65086-restart.c
> @@ -0,0 +1,99 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021 Emil Renner Berthing
> + */
> +
> +#include <linux/mfd/tps65086.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +
> +struct tps65086_restart {
> +	struct notifier_block handler;
> +	struct tps65086 *tps;
> +	struct device *dev;
> +};
> +
> +static int tps65086_restart_notify(struct notifier_block *this,
> +				   unsigned long mode, void *cmd)
> +{
> +	struct tps65086_restart *tps65086_restart =
> +		container_of(this, struct tps65086_restart, handler);
> +	int ret;
> +
> +	ret = regmap_write(tps65086_restart->tps->regmap, TPS65086_FORCESHUTDN, 1);
> +	if (ret) {
> +		dev_err(tps65086_restart->dev, "%s: error writing to tps65086 pmic: %d\n",
> +			__func__, ret);
> +		return NOTIFY_DONE;
> +	}
> +
> +	/* give it a little time */
> +	mdelay(200);
> +
> +	WARN_ON(1);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int tps65086_restart_probe(struct platform_device *pdev)
> +{
> +	struct tps65086_restart *tps65086_restart;
> +	int ret;
> +
> +	tps65086_restart = devm_kzalloc(&pdev->dev, sizeof(*tps65086_restart), GFP_KERNEL);
> +	if (!tps65086_restart)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, tps65086_restart);
> +
> +	tps65086_restart->handler.notifier_call = tps65086_restart_notify;
> +	tps65086_restart->handler.priority = 192;
> +	tps65086_restart->tps = dev_get_drvdata(pdev->dev.parent);
> +	tps65086_restart->dev = &pdev->dev;
> +
> +	ret = register_restart_handler(&tps65086_restart->handler);
> +	if (ret) {
> +		dev_err(&pdev->dev, "%s: cannot register restart handler: %d\n",
> +			__func__, ret);
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static int tps65086_restart_remove(struct platform_device *pdev)
> +{
> +	struct tps65086_restart *tps65086_restart = platform_get_drvdata(pdev);
> +	int ret;
> +
> +	ret = unregister_restart_handler(&tps65086_restart->handler);
> +	if (ret) {
> +		dev_err(&pdev->dev, "%s: cannot unregister restart handler: %d\n",
> +			__func__, ret);
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct platform_device_id tps65086_restart_id_table[] = {
> +	{ "tps65086-restart", },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(platform, tps65086_restart_id_table);
> +
> +static struct platform_driver tps65086_restart_driver = {
> +	.driver = {
> +		.name = "tps65086-restart",
> +	},
> +	.probe = tps65086_restart_probe,
> +	.remove = tps65086_restart_remove,
> +	.id_table = tps65086_restart_id_table,
> +};
> +module_platform_driver(tps65086_restart_driver);
> +
> +MODULE_AUTHOR("Emil Renner Berthing <kernel@esmil.dk>");
> +MODULE_DESCRIPTION("TPS65086 restart driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.32.0
>