Re: Re: [PATCH v2 15/17] power: reset: mt6323: add a driver for MT6323 power controller

Sean Wang
2018-05-02T02:31:23Z

On Tue, 2018-05-01 at 14:56 +0200, Sebastian Reichel wrote:
> Hi,
>
> On Wed, Apr 25, 2018 at 05:32:41PM +0800, sean.wang@mediatek.com wrote:
> > From: Sean Wang <sean.wang@mediatek.com>
> >
> > The power device is responsible for externally down or up the power
> > of the remote MediaTek SoC through the tiny circuit BBPU inside PMIC RTC.
> >
> > Though it's a part of RTC device, it would be better to be a standalone
> > driver than to be a part of existent RTC driver so as to let us make
> > concentration on works about power-controlling topic and to obtain
> > improvements while the subsystem power/reset constantly growing.
>
> I don't understand the above sentence. (I'm fine with adding the
> driver)

Which I was actually meaning is that taking the poweroff driver as the
standalone one and placing it under driver/reset/power seems can simply
get a help from its subsystem either for function extension or bugfix in
the future. I thought that way is better than just an embedded one
somewhere in rtc driver or other drivers.

> > Currently, the most basic functionality supported is to just power off
> > the system by writing to a special bit field in BBPU register after the
> > system has reached pm_poweroff.
> >
> > Signed-off-by: Sean Wang <sean.wang@mediatek.com>
> > ---
> > drivers/power/reset/Kconfig | 10 ++++
> > drivers/power/reset/Makefile | 1 +
> > drivers/power/reset/mt6323-poweroff.c | 97 +++++++++++++++++++++++++++++++++++
> > include/linux/mfd/mt6397/rtc.h | 1 +
> > 4 files changed, 109 insertions(+)
> > create mode 100644 drivers/power/reset/mt6323-poweroff.c
> >
> > diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
> > index df58fc8..7b49d71 100644
> > --- a/drivers/power/reset/Kconfig
> > +++ b/drivers/power/reset/Kconfig
> > @@ -128,6 +128,16 @@ config POWER_RESET_LTC2952
> > This driver supports an external powerdown trigger and board power
> > down via the LTC2952. Bindings are made in the device tree.
> >
> > +config POWER_RESET_MT6323
> > + bool "MediaTek MT6323 power-off driver"
> > + depends on MFD_MT6397
> > + help
> > + The power-off driver is responsible for externally shutdown down
> > + the power of a remote MediaTek SoC MT6323 is connected to through
> > + controlling a tiny circuit BBPU inside MT6323 RTC.
> > +
> > + Say Y if you have a board where MT6323 could be found.
> > +
> > config POWER_RESET_QNAP
> > bool "QNAP power-off driver"
> > depends on OF_GPIO && PLAT_ORION
> > diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
> > index 7778c74..8836172 100644
> > --- a/drivers/power/reset/Makefile
> > +++ b/drivers/power/reset/Makefile
> > @@ -11,6 +11,7 @@ obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
> > obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
> > obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
> > obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
> > +obj-$(CONFIG_POWER_RESET_MT6323) += mt6323-poweroff.o
> > obj-$(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
> > diff --git a/drivers/power/reset/mt6323-poweroff.c b/drivers/power/reset/mt6323-poweroff.c
> > new file mode 100644
> > index 0000000..c195766
> > --- /dev/null
> > +++ b/drivers/power/reset/mt6323-poweroff.c
> > @@ -0,0 +1,97 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Power off through MediaTek PMIC
> > + *
> > + * Copyright (C) 2018 MediaTek Inc.
> > + *
> > + * Author: Sean Wang <sean.wang@mediatek.com>
> > + *
> > + */
> > +
> > +#include <linux/err.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
>
> Not needed

Will be removed.

>
> > +#include <linux/platform_device.h>
> > +#include <linux/mfd/mt6397/core.h>
> > +#include <linux/mfd/mt6397/rtc.h>
> > +
> > +struct mt6323_pwrc {
> > + struct device *dev;
> > + struct regmap *regmap;
> > + u32 base;
> > +};
> > +
> > +static struct mt6323_pwrc *mt_pwrc;
> > +
> > +static void mt6323_do_pwroff(void)
> > +{
> > + struct mt6323_pwrc *pwrc = mt_pwrc;
> > + unsigned int val;
> > + int ret;
> > +
> > + regmap_write(pwrc->regmap, pwrc->base + RTC_BBPU, RTC_BBPU_KEY);
> > + regmap_write(pwrc->regmap, pwrc->base + RTC_WRTGR, 1);
> > +
> > + ret = regmap_read_poll_timeout(pwrc->regmap,
> > + pwrc->base + RTC_BBPU, val,
> > + !(val & RTC_BBPU_CBUSY),
> > + MTK_RTC_POLL_DELAY_US,
> > + MTK_RTC_POLL_TIMEOUT);
> > + if (ret)
> > + dev_err(pwrc->dev, "failed to write BBPU: %d\n", ret);
> > +
> > + /* Wait some time until system down, otherwise, notice with a warn */
> > + mdelay(1000);
> > +
> > + WARN_ONCE(1, "Unable to power off system\n");
> > +}
> > +
> > +static int mt6323_pwrc_probe(struct platform_device *pdev)
> > +{
> > + struct mt6397_chip *mt6397_chip = dev_get_drvdata(pdev->dev.parent);
> > + struct mt6323_pwrc *pwrc;
> > + struct resource *res;
> > +
> > + pwrc = devm_kzalloc(&pdev->dev, sizeof(*pwrc), GFP_KERNEL);
> > + if (!pwrc)
> > + return -ENOMEM;
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + pwrc->base = res->start;
> > + pwrc->regmap = mt6397_chip->regmap;
> > + pwrc->dev = &pdev->dev;
> > + mt_pwrc = pwrc;
> > +
> > + pm_power_off = &mt6323_do_pwroff;
> > +
> > + return 0;
> > +}
> > +
> > +static int mt6323_pwrc_remove(struct platform_device *pdev)
> > +{
> > + if (pm_power_off == &mt6323_do_pwroff)
> > + pm_power_off = NULL;
> > +
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id mt6323_pwrc_dt_match[] = {
> > + { .compatible = "mediatek,mt6323-pwrc" },
> > + {},
> > +};
> > +MODULE_DEVICE_TABLE(of, mt6323_pwrc_dt_match);
>
> Don't forget to remove the DT table when you respin the series for
> the requested binding changes.
>

Thanks. This table will be removed in the next version.

> > +static struct platform_driver mt6323_pwrc_driver = {
> > + .probe = mt6323_pwrc_probe,
> > + .remove = mt6323_pwrc_remove,
> > + .driver = {
> > + .name = "mt6323-pwrc",
> > + .of_match_table = mt6323_pwrc_dt_match,
> > + },
> > +};
> > +
> > +module_platform_driver(mt6323_pwrc_driver);
> > +
> > +MODULE_DESCRIPTION("Poweroff driver for MT6323 PMIC");
> > +MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
> > +MODULE_LICENSE("GPL v2");
> > diff --git a/include/linux/mfd/mt6397/rtc.h b/include/linux/mfd/mt6397/rtc.h
> > index 480977c..ac932c9 100644
> > --- a/include/linux/mfd/mt6397/rtc.h
> > +++ b/include/linux/mfd/mt6397/rtc.h
> > @@ -16,6 +16,7 @@
> >
> > #define RTC_BBPU 0x0000
> > #define RTC_BBPU_CBUSY BIT(6)
> > +#define RTC_BBPU_KEY (0x43 << 8)
> >
> > #define RTC_WRTGR 0x003c
>
> The driver looks fine otherwise.
>

Thanks.

> -- Sebastian
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