Add support to MT6323 RTC and its power device

From: Sean Wang <[email protected]>

Adding device-tree binding for the power controller which is a tiny circuit block present as a part of MT6323 PMIC and is responsible for externally powering off or on a remote SoC the PMIC is connected to.

Cc devicetree at vger.kernel.org

Signed-off-by Sean Wang <[email protected]>

---
 .../bindings/power/reset/mt6323-poweroff.txt         | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt

Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt new file +8 -0

new file mode 100644
index 0000000..6f7c590
@@ -0,0 +1,20 @@
+Device Tree Bindings for Power Controller on MediaTek PMIC
+
+The power controller which could be found on PMIC is responsible for externally
+powering off or on the remote MediaTek SoC through the circuit BBPU.
+
+Required properties:
+- compatible: Should be one of follows
+	"mediatek,mt6323-pwrc": for MT6323 PMIC

Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt new file +2 -0

+		};
+	}

Signature · 1 line

2.7.4

Quoted 27 lines · sean.wang at mediatek.com

From: Sean Wang <[email protected]>

Adding device-tree binding for the power controller which is a tiny circuit block present as a part of MT6323 PMIC and is responsible for externally powering off or on a remote SoC the PMIC is connected to.

Cc devicetree at vger.kernel.org

Signed-off-by Sean Wang <[email protected]>

---
 .../bindings/power/reset/mt6323-poweroff.txt         | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt

Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt new file +8 -0

new file mode 100644
index 0000000..6f7c590
@@ -0,0 +1,20 @@
+Device Tree Bindings for Power Controller on MediaTek PMIC
+
+The power controller which could be found on PMIC is responsible for externally
+powering off or on the remote MediaTek SoC through the circuit BBPU.
+
+Required properties:
+- compatible: Should be one of follows
+	"mediatek,mt6323-pwrc": for MT6323 PMIC

Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt line 18

Quoted 10 lines

Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt new file +10 -0

+
+Example:
+
+	pmic {
+		compatible = "mediatek,mt6323";
+
+		...
+
+		power-controller {
+			compatible = "mediatek,mt6323-pwrc";

Why do you need this in DT? It doesn't define any resources. The parent can just as well register a reset or poweroff handler.

Rob

Quoted 5 lines

Documentation/devicetree/bindings/power/reset/mt6323-poweroff.txt new file +2 -0

+		};
+	}

Signature · 1 line

2.7.4

From: Sean Wang <[email protected]>

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 <[email protected]>

---
 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

drivers/power/reset/Kconfig +10 -0

index df58fc8..7b49d71 100644
@@ -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

drivers/power/reset/Makefile +1 -0

index 7778c74..8836172 100644
@@ -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

drivers/power/reset/mt6323-poweroff.c new file +3 -0

new file mode 100644
index 0000000..c195766
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Power off through MediaTek PMIC

drivers/power/reset/mt6323-poweroff.c new file +59 -0

+#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)

drivers/power/reset/mt6323-poweroff.c new file +14 -0

+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 <[email protected]>");
+MODULE_LICENSE("GPL v2");

include/linux/mfd/mt6397/rtc.h +0 -0

index 480977c..ac932c9 100644

Hi,

Quoted 5 lines · sean.wang at mediatek.com

From: Sean Wang <[email protected]>

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.

Quoted 4 lines

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)

Quoted 59 lines

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 <[email protected]>

---
 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

drivers/power/reset/Kconfig +10 -0

index df58fc8..7b49d71 100644
@@ -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

drivers/power/reset/Makefile +1 -0

index 7778c74..8836172 100644
@@ -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

drivers/power/reset/mt6323-poweroff.c new file +7 -0

new file mode 100644
index 0000000..c195766
@@ -0,0 +1,97 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Power off through MediaTek PMIC
+ *
+ * Copyright (C) 2018 MediaTek Inc.
+ *
+ * Author: Sean Wang <[email protected]>

drivers/power/reset/mt6323-poweroff.c line 13

Quoted 6 lines

drivers/power/reset/mt6323-poweroff.c new file +6 -0

+ *
+ */
+
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/of.h>

Not needed

Quoted 65 lines

drivers/power/reset/mt6323-poweroff.c new file +64 -0

+#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;
+}
+

drivers/power/reset/mt6323-poweroff.c line 82

Quoted 5 lines

drivers/power/reset/mt6323-poweroff.c new file +5 -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.

Quoted 20 lines

drivers/power/reset/mt6323-poweroff.c new file +14 -0

+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 <[email protected]>");
+MODULE_LICENSE("GPL v2");

include/linux/mfd/mt6397/rtc.h +0 -0

index 480977c..ac932c9 100644
@@ -16,6 +16,7 @@
 

include/linux/mfd/mt6397/rtc.h line 21

Quoted 5 lines

include/linux/mfd/mt6397/rtc.h +1 -0

 #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.

-- Sebastian
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Linux-mediatek mailing list
Linux-mediatek at lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

From: Sean Wang <[email protected]>

Add device-tree binding for MediaTek PMIC based RTC

Cc devicetree at vger.kernel.org

Signed-off-by Sean Wang <[email protected]>

---
 .../devicetree/bindings/rtc/rtc-mt6397.txt         | 29 ++++++++++++++++++++++
 1 file changed, 29 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/rtc-mt6397.txt