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 at mediatek.com wrote:

quoted

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.

quoted

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.

quoted

+#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.

quoted

+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 [off-list ref]");
+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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