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

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>
+#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);
+
+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

--
2.7.4
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