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

To: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Subject: Re: [PATCH v2 08/13] power: reset: Add a driver for the Microsemi Ocelot reset
From: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Date: Fri, 8 Dec 2017 18:15:22 +0100
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
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References: <20171208154618.20105-1-alexandre.belloni@free-electrons.com> <20171208154618.20105-9-alexandre.belloni@free-electrons.com> <20171208170755.n6eqgn2jkjh4rbo5@earth>
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On 08/12/2017 at 18:07:55 +0100, Sebastian Reichel wrote:
> 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@kernel.org>
> > Cc: linux-pm@vger.kernel.org
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@free-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?
> 

Absolutely, and I think this is the best plan.

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



-- 
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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