[PATCH v1 14/16] power: reset: mediatek: add a power-off driver using PMIC RTC device

sean.wang
2018-03-23T09:15:38Z

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 against existent RTC driver so as to make concentration on works
about power-controlling topic and help gather more improvements while the
subsystem's 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 | 9 +++
drivers/power/reset/Makefile | 1 +
drivers/power/reset/mt6397-rtc-poweroff.c | 100 ++++++++++++++++++++++++++++++
include/linux/rtc/mt6397.h | 1 +
4 files changed, 111 insertions(+)
create mode 100644 drivers/power/reset/mt6397-rtc-poweroff.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index a102e74..0bd4603 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -121,6 +121,15 @@ 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_MT6397_RTC
+ bool "MediaTek MT6397 RTC power-off driver"
+ help
+ This driver supports turning off a remote MediaTek SoC by
+ controlling BBPU on MT6397 or MT6323 RTC.
+
+ Select this if you're building a kernel with your MediaTek SoC
+ with an equipment with MT6397 or MT6323 PMIC.
+
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 dcc92f5..d45099e 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-$(CONFIG_POWER_RESET_MT6397_RTC) += mt6397-rtc-poweroff.o
obj-$(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/mt6397-rtc-poweroff.c b/drivers/power/reset/mt6397-rtc-poweroff.c
new file mode 100644
index 0000000..9b57366
--- /dev/null
+++ b/drivers/power/reset/mt6397-rtc-poweroff.c
@@ -0,0 +1,100 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Power-off using MediaTek PMIC RTC device
+ *
+ * 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/rtc/mt6397.h>
+
+struct mt6397_rtc_powercon {
+ struct device *dev;
+ struct mt6397_rtc *rtc;
+};
+
+static struct mt6397_rtc_powercon *mt_powercon;
+
+static void mt6397_rtc_do_poweroff(void)
+{
+ struct mt6397_rtc_powercon *powercon = mt_powercon;
+ struct mt6397_rtc *rtc = powercon->rtc;
+ unsigned int val;
+ int ret;
+
+ regmap_write(rtc->regmap, rtc->addr_base + RTC_BBPU, RTC_BBPU_KEY);
+ regmap_write(rtc->regmap, rtc->addr_base + RTC_WRTGR, 1);
+
+ ret = regmap_read_poll_timeout(rtc->regmap,
+ rtc->addr_base + RTC_BBPU, val,
+ !(val & RTC_BBPU_CBUSY),
+ MTK_RTC_POLL_DELAY_US,
+ MTK_RTC_POLL_TIMEOUT);
+ if (ret)
+ dev_err(powercon->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 poweroff system\n");
+}
+
+static int mt6397_rtc_poweroff_probe(struct platform_device *pdev)
+{
+ struct mt6397_rtc *rtc = dev_get_drvdata(pdev->dev.parent);
+ struct mt6397_rtc_powercon *powercon;
+
+ if (!rtc) {
+ dev_err(&pdev->dev, "Can't find RTC as the parent\n");
+ return -ENODEV;
+ }
+
+ powercon = devm_kzalloc(&pdev->dev, sizeof(*powercon), GFP_KERNEL);
+ if (!powercon)
+ return -ENOMEM;
+
+ powercon->dev = &pdev->dev;
+ powercon->rtc = rtc;
+ mt_powercon = powercon;
+
+ pm_power_off = &mt6397_rtc_do_poweroff;
+
+ return 0;
+}
+
+static int mt6397_rtc_poweroff_remove(struct platform_device *pdev)
+{
+ if (pm_power_off == &mt6397_rtc_do_poweroff)
+ pm_power_off = NULL;
+
+ return 0;
+}
+
+static const struct of_device_id mt6397_rtc_poweroff_dt_match[] = {
+ { .compatible = "mediatek,mt6323-rtc-poweroff" },
+ { .compatible = "mediatek,mt6397-rtc-poweroff" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, mt6397_rtc_poweroff_dt_match);
+
+static struct platform_driver mt6397_rtc_poweroff_driver = {
+ .probe = mt6397_rtc_poweroff_probe,
+ .remove = mt6397_rtc_poweroff_remove,
+ .driver = {
+ .name = "mt6397-rtc-poweroff",
+ .of_match_table = mt6397_rtc_poweroff_dt_match,
+ },
+};
+
+module_platform_driver(mt6397_rtc_poweroff_driver);
+
+MODULE_DESCRIPTION("Poweroff driver using MediaTek PMIC RTC");
+MODULE_AUTHOR("Sean Wang <sean.wang@mediatek.com>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:mt6397-rtc-poweroff");
diff --git a/include/linux/rtc/mt6397.h b/include/linux/rtc/mt6397.h
index 4b19f51..e618974 100644
--- a/include/linux/rtc/mt6397.h
+++ b/include/linux/rtc/mt6397.h
@@ -17,6 +17,7 @@

#define RTC_BBPU 0x0000
#define RTC_BBPU_CBUSY BIT(6)
+#define RTC_BBPU_KEY (0x43 << 8)

#define RTC_WRTGR 0x003c

--
2.7.4