power: reset: imx-snvs-poweroff: add power off driver for i.mx6

This driver register pm_power_off with snvs power off function. If
your boards NOT use PMIC_ON_REQ to turn on/off external pmic, or use
other pin to do, please disable the driver in dts, otherwise, your
pm_power_off maybe overwrote by this driver.

Signed-off-by: Robin Gong <[e-mail]>
Acked-By: Sebastian Reichel <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

Documentation/devicetree/bindings/power_supply/imx-snvs-poweroff.txt

···
+i.mx6 Poweroff Driver
+
+SNVS_LPCR in SNVS module can power off the whole system by pull
+PMIC_ON_REQ low if PMIC_ON_REQ is connected with external PMIC.
+If you don't want to use PMIC_ON_REQ as power on/off control,
+please set status='disabled' to disable this driver.
+
+Required Properties:
+-compatible: "fsl,sec-v4.0-poweroff"
+-reg: Specifies the physical address of the SNVS_LPCR register
+
+Example:
+	snvs@020cc000 {
+		compatible = "fsl,sec-v4.0-mon", "simple-bus";
+		#address-cells = <1>;
+		#size-cells = <1>;
+		ranges = <0 0x020cc000 0x4000>;
+		.....
+		snvs_poweroff: snvs-poweroff@38 {
+			compatible = "fsl,sec-v4.0-poweroff";
+			reg = <0x38 0x4>;
+		};
+	}

drivers/power/reset/Kconfig

···
 	help
 	  Reboot support for Hisilicon boards.
 
+config POWER_RESET_IMX
+	bool "IMX6 power-off driver"
+	depends on POWER_RESET && SOC_IMX6
+	help
+	  This driver support power off external PMIC by PMIC_ON_REQ on i.mx6
+	  boards.If you want to use other pin to control external power,please
+	  say N here or disable in dts to make sure pm_power_off never be
+	  overwrote wrongly by this driver.
+
 config POWER_RESET_MSM
 	bool "Qualcomm MSM power-off driver"
 	depends on ARCH_QCOM

drivers/power/reset/Makefile

···
 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_IMX) += imx-snvs-poweroff.o
 obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
 obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
 obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o

drivers/power/reset/imx-snvs-poweroff.c

···
+/* Power off driver for i.mx6
+ * Copyright (c) 2014, FREESCALE CORPORATION.  All rights reserved.
+ *
+ * based on msm-poweroff.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+
+static void __iomem *snvs_base;
+
+static void do_imx_poweroff(void)
+{
+	u32 value = readl(snvs_base);
+
+	/* set TOP and DP_EN bit */
+	writel(value | 0x60, snvs_base);
+}
+
+static int imx_poweroff_probe(struct platform_device *pdev)
+{
+	snvs_base = of_iomap(pdev->dev.of_node, 0);
+	if (!snvs_base) {
+		dev_err(&pdev->dev, "failed to get memory\n");
+		return -ENODEV;
+	}
+
+	pm_power_off = do_imx_poweroff;
+	return 0;
+}
+
+static const struct of_device_id of_imx_poweroff_match[] = {
+	{ .compatible = "fsl,sec-v4.0-poweroff", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, of_imx_poweroff_match);
+
+static struct platform_driver imx_poweroff_driver = {
+	.probe = imx_poweroff_probe,
+	.driver = {
+		.name = "imx-snvs-poweroff",
+		.of_match_table = of_match_ptr(of_imx_poweroff_match),
+	},
+};
+
+static int __init imx_poweroff_init(void)
+{
+	return platform_driver_register(&imx_poweroff_driver);
+}
+device_initcall(imx_poweroff_init);