linux-kernel - Re: [PATCH v2 08/13] power: reset: Add a driver for the Microsemi Ocelot reset

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Date:   Fri, 8 Dec 2017 18:07:55 +0100
From:   Sebastian Reichel <sebastian.reichel@...labora.co.uk>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:     Ralf Baechle <ralf@...ux-mips.org>, linux-mips@...ux-mips.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v2 08/13] power: reset: Add a driver for the Microsemi
 Ocelot reset

Hi,

On Fri, Dec 08, 2017 at 04:46:13PM +0100, Alexandre Belloni wrote:
> The Microsemi Ocelot SoC has a register allowing to reset the MIPS core.
> Unfortunately, the syscon-reboot driver can't be used directly (but almost)
> as the reset control may be disabled using another register.
> 
> Cc: Sebastian Reichel <sre@...nel.org>
> Cc: linux-pm@...r.kernel.org
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

Is it safe to apply this and the DT binding patch (once it has Rob's
Ack-by) via the power-supply tree?

Reviewed-by: Sebastian Reichel <sebastian.reichel@...labora.co.uk>

-- Sebastian

>  drivers/power/reset/Kconfig        |  7 ++++
>  drivers/power/reset/Makefile       |  1 +
>  drivers/power/reset/ocelot-reset.c | 86 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 94 insertions(+)
>  create mode 100644 drivers/power/reset/ocelot-reset.c
> 
> diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> index ca0de1a78e85..2372f8e1040d 100644
> --- a/drivers/power/reset/Kconfig
> +++ b/drivers/power/reset/Kconfig
> @@ -113,6 +113,13 @@ config POWER_RESET_MSM
>  	help
>  	  Power off and restart support for Qualcomm boards.
>  
> +config POWER_RESET_OCELOT_RESET
> +	bool "Microsemi Ocelot reset driver"
> +	depends on MSCC_OCELOT || COMPILE_TEST
> +	select MFD_SYSCON
> +	help
> +	  This driver supports restart for Microsemi Ocelot SoC.
> +
>  config POWER_RESET_PIIX4_POWEROFF
>  	tristate "Intel PIIX4 power-off driver"
>  	depends on PCI
> diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
> index aeb65edb17b7..df9d92291c67 100644
> --- a/drivers/power/reset/Makefile
> +++ b/drivers/power/reset/Makefile
> @@ -12,6 +12,7 @@ obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
>  obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
>  obj-$(CONFIG_POWER_RESET_IMX) += imx-snvs-poweroff.o
>  obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
> +obj-$(CONFIG_POWER_RESET_OCELOT_RESET) += ocelot-reset.o
>  obj-$(CONFIG_POWER_RESET_PIIX4_POWEROFF) += piix4-poweroff.o
>  obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
>  obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
> diff --git a/drivers/power/reset/ocelot-reset.c b/drivers/power/reset/ocelot-reset.c
> new file mode 100644
> index 000000000000..1fb14bf17191
> --- /dev/null
> +++ b/drivers/power/reset/ocelot-reset.c
> @@ -0,0 +1,86 @@
> +// SPDX-License-Identifier: (GPL-2.0 OR MIT)
> +/*
> + * Microsemi MIPS SoC reset driver
> + *
> + * License: Dual MIT/GPL
> + * Copyright (c) 2017 Microsemi Corporation
> + */
> +#include <linux/delay.h>
> +#include <linux/io.h>
> +#include <linux/notifier.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/of_address.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/reboot.h>
> +#include <linux/regmap.h>
> +
> +struct ocelot_reset_context {
> +	struct regmap *chip_regs;
> +	struct regmap *cpu_ctrl;
> +	struct notifier_block restart_handler;
> +};
> +
> +#define ICPU_CFG_CPU_SYSTEM_CTRL_RESET 0x20
> +#define CORE_RST_PROTECT BIT(2)
> +
> +#define CHIP_REGS_SOFT_RST 0x8
> +#define SOFT_CHIP_RST BIT(0)
> +
> +static int ocelot_restart_handle(struct notifier_block *this,
> +				 unsigned long mode, void *cmd)
> +{
> +	struct ocelot_reset_context *ctx = container_of(this, struct
> +							ocelot_reset_context,
> +							restart_handler);
> +
> +	/* Make sure the core is not protected from reset */
> +	regmap_update_bits(ctx->cpu_ctrl, ICPU_CFG_CPU_SYSTEM_CTRL_RESET,
> +			   CORE_RST_PROTECT, 0);
> +
> +	regmap_write(ctx->chip_regs, CHIP_REGS_SOFT_RST, SOFT_CHIP_RST);
> +
> +	pr_emerg("Unable to restart system\n");
> +	return NOTIFY_DONE;
> +}
> +
> +static int ocelot_reset_probe(struct platform_device *pdev)
> +{
> +	struct ocelot_reset_context *ctx;
> +	struct device *dev = &pdev->dev;
> +	int err;
> +
> +	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
> +	if (!ctx)
> +		return -ENOMEM;
> +
> +	ctx->chip_regs = syscon_node_to_regmap(of_get_parent(dev->of_node));
> +	if (IS_ERR(ctx->chip_regs))
> +		return PTR_ERR(ctx->chip_regs);
> +
> +	ctx->cpu_ctrl = syscon_regmap_lookup_by_compatible("mscc,ocelot-cpu-syscon");
> +	if (IS_ERR(ctx->cpu_ctrl))
> +		return PTR_ERR(ctx->cpu_ctrl);
> +
> +	ctx->restart_handler.notifier_call = ocelot_restart_handle;
> +	ctx->restart_handler.priority = 192;
> +	err = register_restart_handler(&ctx->restart_handler);
> +	if (err)
> +		dev_err(dev, "can't register restart notifier (err=%d)\n", err);
> +
> +	return err;
> +}
> +
> +static const struct of_device_id ocelot_reset_of_match[] = {
> +	{ .compatible = "mscc,ocelot-chip-reset" },
> +	{}
> +};
> +
> +static struct platform_driver ocelot_reset_driver = {
> +	.probe = ocelot_reset_probe,
> +	.driver = {
> +		.name = "ocelot-chip-reset",
> +		.of_match_table = ocelot_reset_of_match,
> +	},
> +};
> +builtin_platform_driver(ocelot_reset_driver);
> -- 
> 2.15.1
> 

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