linux-kernel - Re: [PATCH 03/12] power: reset: Add TI-SCI reboot driver

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Message-ID: <20240201211534.dv6qu7ila54vqykn@cheating>
Date: Thu, 1 Feb 2024 15:15:34 -0600
From: Nishanth Menon <nm@...com>
To: Andrew Davis <afd@...com>
CC: Tero Kristo <kristo@...nel.org>, Santosh Shilimkar <ssantosh@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski
	<krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>, Sebastian Reichel <sre@...nel.org>,
        Vignesh Raghavendra <vigneshr@...com>,
        <linux-arm-kernel@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>
Subject: Re: [PATCH 03/12] power: reset: Add TI-SCI reboot driver

On 16:19-20240131, Andrew Davis wrote:
> This reboot driver calls into firmware using TI-SCI to reboot the system.
> We register the handler with low priority as we want PSCI to remain the
> main way these devices are rebooted. This driver acts as a fallback if
> PSCI is not able to reboot the system.
> 
> Signed-off-by: Andrew Davis <afd@...com>
> ---
>  MAINTAINERS                         |  1 +
>  drivers/power/reset/Kconfig         |  7 ++++
>  drivers/power/reset/Makefile        |  1 +
>  drivers/power/reset/ti-sci-reboot.c | 63 +++++++++++++++++++++++++++++
>  4 files changed, 72 insertions(+)
>  create mode 100644 drivers/power/reset/ti-sci-reboot.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 45983bb174fe4..ee67ea497fc56 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -21758,6 +21758,7 @@ F:	drivers/clk/keystone/sci-clk.c
>  F:	drivers/firmware/ti_sci*
>  F:	drivers/irqchip/irq-ti-sci-inta.c
>  F:	drivers/irqchip/irq-ti-sci-intr.c
> +F:	drivers/power/reset/ti-sci-reboot.c
>  F:	drivers/reset/reset-ti-sci.c
>  F:	drivers/soc/ti/ti_sci_inta_msi.c
>  F:	drivers/pmdomain/ti/ti_sci_pm_domains.c
> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> index fece990af4a75..d3e91e54cae24 100644
> --- a/drivers/power/reset/Kconfig
> +++ b/drivers/power/reset/Kconfig
> @@ -205,6 +205,13 @@ config POWER_RESET_ST
>  	help
>  	  Reset support for STMicroelectronics boards.
>  
> +config POWER_RESET_TI_SCI
> +	tristate "TI System Control Interface (TI-SCI) reboot driver"
> +	depends on TI_SCI_PROTOCOL
> +	help
> +	  This enables the reboot driver support over TI System Control
> +	  Interface available on some TI's SoCs.
> +
>  config POWER_RESET_TPS65086
>  	bool "TPS65086 restart driver"
>  	depends on MFD_TPS65086
> diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
> index a95d1bd275d18..881ca58a43b9c 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-$(CONFIG_POWER_RESET_TI_SCI) += ti-sci-reboot.o
>  obj-$(CONFIG_POWER_RESET_TPS65086) += tps65086-restart.o
>  obj-$(CONFIG_POWER_RESET_VERSATILE) += arm-versatile-reboot.o
>  obj-$(CONFIG_POWER_RESET_VEXPRESS) += vexpress-poweroff.o
> diff --git a/drivers/power/reset/ti-sci-reboot.c b/drivers/power/reset/ti-sci-reboot.c
> new file mode 100644
> index 0000000000000..400bd5d740f8b
> --- /dev/null
> +++ b/drivers/power/reset/ti-sci-reboot.c
> @@ -0,0 +1,63 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Texas Instrument's System Control Interface (TI-SCI) reboot driver
> + *
> + * Copyright (C) 2024 Texas Instruments Incorporated - https://www.ti.com/
> + *	Andrew Davis <afd@...com>
> + */
> +
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +
> +#include <linux/soc/ti/ti_sci_protocol.h>
> +
> +static int ti_sci_reboot_handler(struct sys_off_data *data)
> +{
> +	const struct ti_sci_handle *sci = data->cb_data;
> +	const struct ti_sci_core_ops *core_ops = &sci->ops.core_ops;
> +
> +	core_ops->reboot_device(sci);
> +
> +	return NOTIFY_DONE;
> +}
> +
> +static int ti_sci_reboot_probe(struct platform_device *pdev)
> +{
> +	const struct ti_sci_handle *sci;
> +	int err;
> +
> +	sci = devm_ti_sci_get_handle(&pdev->dev);
> +	if (IS_ERR(sci))
> +		return PTR_ERR(sci);
> +
> +	err = devm_register_sys_off_handler(&pdev->dev,
> +					    SYS_OFF_MODE_RESTART,
> +					    SYS_OFF_PRIO_LOW,
> +					    ti_sci_reboot_handler,
> +					    (void *)sci);
> +	if (err)
> +		return dev_err_probe(&pdev->dev, err, "Cannot register restart handler\n");
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ti_sci_reboot_of_match[] = {
> +	{ .compatible = "ti,sci-reboot", },
> +	{ /* sentinel */ },
> +};
> +MODULE_DEVICE_TABLE(of, ti_sci_reboot_of_match);
> +
> +static struct platform_driver ti_sci_reboot_driver = {
> +	.probe = ti_sci_reboot_probe,
> +	.driver = {
> +		.name = "ti-sci-reboot",
> +		.of_match_table = ti_sci_reboot_of_match,
> +	},
> +};
> +module_platform_driver(ti_sci_reboot_driver);
> +
> +MODULE_AUTHOR("Andrew Davis <afd@...com>");
> +MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reboot driver");
> +MODULE_LICENSE("GPL");
> -- 
> 2.39.2

Will assume the patch to go via Sebastien. Will be good for the dts to
go via SoC tree. So hoping Sebastien will just pick the driver and
bindings.

Reviewed-by: Nishanth Menon <nm@...com>
-- 
Regards,
Nishanth Menon
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