[PATCH v15 0/7] power: add power sequence library

@@ -0,0 +1,48 @@
+The generic power sequence library
+
+Some hard-wired devices (eg USB/MMC) need to do power sequence before
+the device can be enumerated on the bus, the typical power sequence
+like: enable USB PHY clock, toggle reset pin, etc. But current
+Linux device driver lacks of such code to do it, it may cause some
+hard-wired devices works abnormal or can't be recognized by
+controller at all. The power sequence will be done before this device
+can be found at the bus.
+
+The power sequence properties is under the device node.
+
+Optional properties:
+- clocks: the input clocks for device.
+- reset-gpios: Should specify the GPIO for reset.
+- reset-duration-us: the duration in microsecond for assert reset signal.
+
+Below is the example of USB power sequence properties on USB device
+nodes which have two level USB hubs.
+
+&usbotg1 {
+	vbus-supply = <&reg_usb_otg1_vbus>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&pinctrl_usb_otg1_id>;
+	status = "okay";
+
+	#address-cells = <1>;
+	#size-cells = <0>;
+	genesys: hub at 1 {
+		compatible = "usb5e3,608";
+		reg = <1>;
+
+		clocks = <&clks IMX6SX_CLK_CKO>;
+		reset-gpios = <&gpio4 5 GPIO_ACTIVE_LOW>; /* hub reset pin */
+		reset-duration-us = <10>;
+
+		#address-cells = <1>;
+		#size-cells = <0>;
+		asix: ethernet at 1 {
+			compatible = "usbb95,1708";
+			reg = <1>;
+
+			clocks = <&clks IMX6SX_CLK_IPG>;
+			reset-gpios = <&gpio4 6 GPIO_ACTIVE_LOW>; /* ethernet_rst */
+			reset-duration-us = <15>;
+		};
+	};
+};

@@ -13,6 +13,10 @@ Required properties:
 - reg: the port number which this device is connecting to, the range
   is 1-31.
 
+Optional properties:
+power sequence properties, see
+Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt for detail
+
 Example:
 
 &usb1 {

@@ -21,8 +25,12 @@ Example:
 	#address-cells = <1>;
 	#size-cells = <0>;
 
-	hub: genesys at 1 {
+	genesys: hub at 1 {
 		compatible = "usb5e3,608";
 		reg = <1>;
+
+		clocks = <&clks IMX6SX_CLK_CKO>;
+		reset-gpios = <&gpio4 5 GPIO_ACTIVE_LOW>; /* hub reset pin */
+		reset-duration-us = <10>;
 	};
 }

@@ -945,6 +945,8 @@
 
 			usbh1: usb at 02184200 {
 				compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <0x02184200 0x200>;
 				interrupts = <0 40 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX6QDL_CLK_USBOH3>;

@@ -959,6 +961,8 @@
 
 			usbh2: usb at 02184400 {
 				compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <0x02184400 0x200>;
 				interrupts = <0 41 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX6QDL_CLK_USBOH3>;

@@ -972,6 +976,8 @@
 
 			usbh3: usb at 02184600 {
 				compatible = "fsl,imx6q-usb", "fsl,imx27-usb";
+				#address-cells = <1>;
+				#size-cells = <0>;
 				reg = <0x02184600 0x200>;
 				interrupts = <0 42 IRQ_TYPE_LEVEL_HIGH>;
 				clocks = <&clks IMX6QDL_CLK_USBOH3>;

@@ -9,6 +9,8 @@
  *
  */
 
+#include <dt-bindings/gpio/gpio.h>
+
 / {
 	aliases {
 		backlight = &backlight;

@@ -58,17 +60,6 @@
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		reg_usb_h1_vbus: regulator at 0 {
-			compatible = "regulator-fixed";
-			reg = <0>;
-			regulator-name = "usb_h1_vbus";
-			regulator-min-microvolt = <5000000>;
-			regulator-max-microvolt = <5000000>;
-			enable-active-high;
-			startup-delay-us = <2>; /* USB2415 requires a POR of 1 us minimum */
-			gpio = <&gpio7 12 0>;
-		};
-
 		reg_panel: regulator at 1 {
 			compatible = "regulator-fixed";
 			reg = <1>;

@@ -188,7 +179,7 @@
 
 		pinctrl_usbh: usbhgrp {
 			fsl,pins = <
-				MX6QDL_PAD_GPIO_17__GPIO7_IO12 0x80000000
+				MX6QDL_PAD_GPIO_17__GPIO7_IO12	0x1b0b0
 				MX6QDL_PAD_NANDF_CS2__CCM_CLKO2 0x130b0
 			>;
 		};

@@ -259,9 +250,16 @@
 &usbh1 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_usbh>;
-	vbus-supply = <&reg_usb_h1_vbus>;
-	clocks = <&clks IMX6QDL_CLK_CKO>;
 	status = "okay";
+
+	usb2415: hub at 1 {
+		compatible = "usb424,2514";
+		reg = <1>;
+
+		clocks = <&clks IMX6QDL_CLK_CKO>;
+		reset-gpios = <&gpio7 12 GPIO_ACTIVE_LOW>;
+		reset-duration-us = <3000>;
+	};
 };
 
 &usdhc3 {

@@ -54,18 +54,6 @@
 		reg = <0x10000000 0x40000000>;
 	};
 
-	reg_usbh1_vbus: regulator-usbhubreset {
-		compatible = "regulator-fixed";
-		regulator-name = "usbh1_vbus";
-		regulator-min-microvolt = <5000000>;
-		regulator-max-microvolt = <5000000>;
-		enable-active-high;
-		startup-delay-us = <2>;
-		pinctrl-names = "default";
-		pinctrl-0 = <&pinctrl_usbh1_hubreset>;
-		gpio = <&gpio7 12 GPIO_ACTIVE_HIGH>;
-	};
-
 	reg_usb_otg_vbus: regulator-usbotgvbus {
 		compatible = "regulator-fixed";
 		regulator-name = "usb_otg_vbus";

@@ -204,12 +192,18 @@
 };
 
 &usbh1 {
-	vbus-supply = <&reg_usbh1_vbus>;
 	pinctrl-names = "default";
 	pinctrl-0 = <&pinctrl_usbh1>;
 	dr_mode = "host";
 	disable-over-current;
 	status = "okay";
+
+	usb2415host: hub at 1 {
+		compatible = "usb424,2513";
+		reg = <1>;
+		reset-gpios = <&gpio7 12 GPIO_ACTIVE_LOW>;
+		reset-duration-us = <3000>;
+	};
 };
 
 &usbotg {

@@ -465,11 +459,6 @@
 			MX6QDL_PAD_GPIO_3__USB_H1_OC 0x1b0b0
 			/* usbh1_b OC */
 			MX6QDL_PAD_GPIO_0__GPIO1_IO00 0x1b0b0
-		>;
-	};
-
-	pinctrl_usbh1_hubreset: usbh1hubresetgrp {
-		fsl,pins = <
 			MX6QDL_PAD_GPIO_17__GPIO7_IO12 0x1b0b0
 		>;
 	};

@@ -39,6 +39,7 @@ config USB
 	tristate "Support for Host-side USB"
 	depends on USB_ARCH_HAS_HCD
 	select USB_COMMON
+	select POWER_SEQUENCE
 	select NLS  # for UTF-8 strings
 	---help---
 	  Universal Serial Bus (USB) is a specification for a serial bus

@@ -28,6 +28,7 @@
 #include <linux/mutex.h>
 #include <linux/random.h>
 #include <linux/pm_qos.h>
+#include <linux/power/pwrseq.h>
 
 #include <linux/uaccess.h>
 #include <asm/byteorder.h>

@@ -1619,6 +1620,7 @@ static void hub_disconnect(struct usb_interface *intf)
 	hub->error = 0;
 	hub_quiesce(hub, HUB_DISCONNECT);
 
+	of_pwrseq_off_list(&hub->pwrseq_list);
 	mutex_lock(&usb_port_peer_mutex);
 
 	/* Avoid races with recursively_mark_NOTATTACHED() */

@@ -1646,12 +1648,42 @@ static void hub_disconnect(struct usb_interface *intf)
 	kref_put(&hub->kref, hub_release);
 }
 
+#ifdef CONFIG_OF
+static int hub_of_pwrseq_on(struct usb_hub *hub)
+{
+	struct device *parent;
+	struct usb_device *hdev = hub->hdev;
+	struct device_node *np;
+	int ret;
+
+	if (hdev->parent)
+		parent = &hdev->dev;
+	else
+		parent = bus_to_hcd(hdev->bus)->self.sysdev;
+
+	for_each_child_of_node(parent->of_node, np) {
+		ret = of_pwrseq_on_list(np, &hub->pwrseq_list);
+		/* Maybe no power sequence library is chosen */
+		if (ret && ret != -ENOENT)
+			return ret;
+	}
+
+	return 0;
+}
+#else
+static int hub_of_pwrseq_on(struct usb_hub *hub)
+{
+	return 0;
+}
+#endif
+
 static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 {
 	struct usb_host_interface *desc;
 	struct usb_endpoint_descriptor *endpoint;
 	struct usb_device *hdev;
 	struct usb_hub *hub;
+	int ret = -ENODEV;
 
 	desc = intf->cur_altsetting;
 	hdev = interface_to_usbdev(intf);

@@ -1756,6 +1788,7 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	INIT_DELAYED_WORK(&hub->leds, led_work);
 	INIT_DELAYED_WORK(&hub->init_work, NULL);
 	INIT_WORK(&hub->events, hub_event);
+	INIT_LIST_HEAD(&hub->pwrseq_list);
 	usb_get_intf(intf);
 	usb_get_dev(hdev);
 

@@ -1769,11 +1802,14 @@ static int hub_probe(struct usb_interface *intf, const struct usb_device_id *id)
 	if (id->driver_info & HUB_QUIRK_CHECK_PORT_AUTOSUSPEND)
 		hub->quirk_check_port_auto_suspend = 1;
 
-	if (hub_configure(hub, endpoint) >= 0)
-		return 0;
+	if (hub_configure(hub, endpoint) >= 0) {
+		ret = hub_of_pwrseq_on(hub);
+		if (!ret)
+			return 0;
+	}
 
 	hub_disconnect(intf);
-	return -ENODEV;
+	return ret;
 }
 
 static int

@@ -3593,14 +3629,19 @@ static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
 
 	/* stop hub_wq and related activity */
 	hub_quiesce(hub, HUB_SUSPEND);
-	return 0;
+	return pwrseq_suspend_list(&hub->pwrseq_list);
 }
 
 static int hub_resume(struct usb_interface *intf)
 {
 	struct usb_hub *hub = usb_get_intfdata(intf);
+	int ret;
 
 	dev_dbg(&intf->dev, "%s\n", __func__);
+	ret = pwrseq_resume_list(&hub->pwrseq_list);
+	if (ret)
+		return ret;
+
 	hub_activate(hub, HUB_RESUME);
 	return 0;
 }

@@ -78,6 +78,7 @@ struct usb_hub {
 	struct delayed_work	init_work;
 	struct work_struct      events;
 	struct usb_port		**ports;
+	struct list_head	pwrseq_list; /* powered pwrseq node list */
 };
 
 /**

@@ -0,0 +1,54 @@
+====================================
+Power Sequence Library
+====================================
+
+:Date: Feb, 2017
+:Author: Peter Chen <peter.chen@nxp.com>
+
+
+Introduction
+============
+
+We have an well-known problem that the device needs to do a power
+sequence before it can be recognized by related host, the typical
+examples are hard-wired mmc devices and usb devices. The host controller
+can't know what kinds of this device is in its bus if the power
+sequence has not done, since the related devices driver's probe calling
+is determined by runtime according to eunumeration results. Besides,
+the devices may have custom power sequence, so the power sequence library
+which is independent with the devices is needed.
+
+Design
+============
+
+The power sequence library includes the core file and customer power
+sequence library. The core file exports interfaces are called by
+host controller driver for power sequence and customer power sequence
+library files to register its power sequence instance to global
+power sequence list. The custom power sequence library creates power
+sequence instance and implement custom power sequence.
+
+Since the power sequence describes hardware design, the description is
+located at board description file, eg, device tree dts file. And
+a specific power sequence belongs to device, so its description
+is under the device node, please refer to:
+Documentation/devicetree/bindings/power/pwrseq/pwrseq-generic.txt
+
+Custom power sequence library allocates one power sequence instance at
+bootup periods using postcore_initcall, this static allocated instance is
+used to compare with device-tree (DT) node to see if this library can be
+used for the node or not. When the result is matched, the core API will
+try to get resourses (->get, implemented at each library) for power
+sequence, if all resources are got, it will try to allocate another
+instance for next possible request from host driver.
+
+Then, the host controller driver can carry out power sequence on for this
+DT node, the library will do corresponding operations, like open clocks,
+toggle gpio, etc. The power sequence off routine will close and free the
+resources, and is called when the parent is removed. And the power
+sequence suspend and resume routine can be called at host driver's
+suspend and resume routine if needed.
+
+The exported interfaces
+.. kernel-doc:: drivers/power/pwrseq/core.c
+   :export:

@@ -10188,6 +10188,15 @@ F:	include/linux/pm_*
 F:	include/linux/powercap.h
 F:	drivers/powercap/
 
+POWER SEQUENCE LIBRARY
+M:	Peter Chen <Peter.Chen@nxp.com>
+T:	git git://git.kernel.org/pub/scm/linux/kernel/git/peter.chen/usb.git
+L:	linux-pm at vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/power/pwrseq/
+F:	drivers/power/pwrseq/
+F:	include/linux/power/pwrseq.h
+
 POWER SUPPLY CLASS/SUBSYSTEM and DRIVERS
 M:	Sebastian Reichel <sre@kernel.org>
 L:	linux-pm at vger.kernel.org

@@ -1,3 +1,4 @@
 source "drivers/power/avs/Kconfig"
 source "drivers/power/reset/Kconfig"
 source "drivers/power/supply/Kconfig"
+source "drivers/power/pwrseq/Kconfig"

@@ -1,3 +1,4 @@
 obj-$(CONFIG_POWER_AVS)		+= avs/
 obj-$(CONFIG_POWER_RESET)	+= reset/
 obj-$(CONFIG_POWER_SUPPLY)	+= supply/
+obj-$(CONFIG_POWER_SEQUENCE)	+= pwrseq/

@@ -0,0 +1,20 @@
+#
+# Power Sequence library
+#
+
+menuconfig POWER_SEQUENCE
+	bool "Power sequence control"
+	help
+	   It is used for drivers which needs to do power sequence
+	   (eg, turn on clock, toggle reset gpio) before the related
+	   devices can be found by hardware, eg, USB bus.
+
+if POWER_SEQUENCE
+
+config PWRSEQ_GENERIC
+	bool "Generic power sequence control"
+	depends on OF
+	help
+	   This is the generic power sequence control library, and is
+	   supposed to support common power sequence usage.
+endif

@@ -0,0 +1,2 @@
+obj-$(CONFIG_POWER_SEQUENCE) += core.o
+obj-$(CONFIG_PWRSEQ_GENERIC) += pwrseq_generic.o

@@ -0,0 +1,335 @@
+/*
+ * core.c	power sequence core file
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen@nxp.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.
+ */
+
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/slab.h>
+#include <linux/power/pwrseq.h>
+
+static DEFINE_MUTEX(pwrseq_list_mutex);
+static LIST_HEAD(pwrseq_list);
+
+static int pwrseq_get(struct device_node *np, struct pwrseq *p)
+{
+	if (p && p->get)
+		return p->get(np, p);
+
+	return -ENOTSUPP;
+}
+
+static int pwrseq_on(struct pwrseq *p)
+{
+	if (p && p->on)
+		return p->on(p);
+
+	return -ENOTSUPP;
+}
+
+static void pwrseq_off(struct pwrseq *p)
+{
+	if (p && p->off)
+		p->off(p);
+}
+
+static void pwrseq_put(struct pwrseq *p)
+{
+	if (p && p->put)
+		p->put(p);
+}
+
+/**
+ * pwrseq_register - Add pwrseq instance to global pwrseq list
+ *
+ * @pwrseq: the pwrseq instance
+ */
+void pwrseq_register(struct pwrseq *pwrseq)
+{
+	mutex_lock(&pwrseq_list_mutex);
+	list_add(&pwrseq->node, &pwrseq_list);
+	mutex_unlock(&pwrseq_list_mutex);
+}
+EXPORT_SYMBOL_GPL(pwrseq_register);
+
+/**
+ * pwrseq_unregister - Remove pwrseq instance from global pwrseq list
+ *
+ * @pwrseq: the pwrseq instance
+ */
+void pwrseq_unregister(struct pwrseq *pwrseq)
+{
+	mutex_lock(&pwrseq_list_mutex);
+	list_del(&pwrseq->node);
+	mutex_unlock(&pwrseq_list_mutex);
+}
+EXPORT_SYMBOL_GPL(pwrseq_unregister);
+
+static struct pwrseq *pwrseq_find_available_instance(struct device_node *np)
+{
+	struct pwrseq *pwrseq;
+
+	mutex_lock(&pwrseq_list_mutex);
+	list_for_each_entry(pwrseq, &pwrseq_list, node) {
+		if (pwrseq->used)
+			continue;
+
+		/* compare compatible string for pwrseq node */
+		if (of_match_node(pwrseq->pwrseq_of_match_table, np)) {
+			pwrseq->used = true;
+			mutex_unlock(&pwrseq_list_mutex);
+			return pwrseq;
+		}
+
+		/* return generic pwrseq instance */
+		if (!strcmp(pwrseq->pwrseq_of_match_table->compatible,
+				"generic")) {
+			pr_debug("using generic pwrseq instance for %s\n",
+				np->full_name);
+			pwrseq->used = true;
+			mutex_unlock(&pwrseq_list_mutex);
+			return pwrseq;
+		}
+	}
+	mutex_unlock(&pwrseq_list_mutex);
+	pr_debug("Can't find any pwrseq instances for %s\n", np->full_name);
+
+	return NULL;
+}
+
+/**
+ * of_pwrseq_on - Carry out power sequence on for device node
+ *
+ * @np: the device node would like to power on
+ *
+ * Carry out a single device power on.  If multiple devices
+ * need to be handled, use of_pwrseq_on_list() instead.
+ *
+ * Return a pointer to the power sequence instance on success,
+ * or an error code otherwise.
+ */
+struct pwrseq *of_pwrseq_on(struct device_node *np)
+{
+	struct pwrseq *pwrseq;
+	int ret;
+
+	pwrseq = pwrseq_find_available_instance(np);
+	if (!pwrseq)
+		return ERR_PTR(-ENOENT);
+
+	ret = pwrseq_get(np, pwrseq);
+	if (ret) {
+		/* Mark current pwrseq as unused */
+		pwrseq->used = false;
+		return ERR_PTR(ret);
+	}
+
+	ret = pwrseq_on(pwrseq);
+	if (ret)
+		goto pwr_put;
+
+	return pwrseq;
+
+pwr_put:
+	pwrseq_put(pwrseq);
+	return ERR_PTR(ret);
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_on);
+
+/**
+ * of_pwrseq_off - Carry out power sequence off for this pwrseq instance
+ *
+ * @pwrseq: the pwrseq instance which related device would like to be off
+ *
+ * This API is used to power off single device, it is the opposite
+ * operation for of_pwrseq_on.
+ */
+void of_pwrseq_off(struct pwrseq *pwrseq)
+{
+	pwrseq_off(pwrseq);
+	pwrseq_put(pwrseq);
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_off);
+
+/**
+ * of_pwrseq_on_list - Carry out power sequence on for list
+ *
+ * @np: the device node would like to power on
+ * @head: the list head for pwrseq list on this bus
+ *
+ * This API is used to power on multiple devices at single bus.
+ * If there are several devices on bus (eg, USB bus), uses this
+ * this API. Otherwise, use of_pwrseq_on instead. After the device
+ * is powered on successfully, it will be added to pwrseq list for
+ * this bus. The caller needs to use mutex_lock for concurrent.
+ *
+ * Return 0 on success, or an error value otherwise.
+ */
+int of_pwrseq_on_list(struct device_node *np, struct list_head *head)
+{
+	struct pwrseq *pwrseq;
+	struct pwrseq_list_per_dev *pwrseq_list_node;
+
+	pwrseq_list_node = kzalloc(sizeof(*pwrseq_list_node), GFP_KERNEL);
+	if (!pwrseq_list_node)
+		return -ENOMEM;
+
+	pwrseq = of_pwrseq_on(np);
+	if (IS_ERR(pwrseq)) {
+		kfree(pwrseq_list_node);
+		return PTR_ERR(pwrseq);
+	}
+
+	pwrseq_list_node->pwrseq = pwrseq;
+	list_add(&pwrseq_list_node->list, head);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_on_list);
+
+/**
+ * of_pwrseq_off_list - Carry out power sequence off for the list
+ *
+ * @head: the list head for pwrseq instance list on this bus
+ *
+ * This API is used to power off all devices on this bus, it is
+ * the opposite operation for of_pwrseq_on_list.
+ * The caller needs to use mutex_lock for concurrent.
+ */
+void of_pwrseq_off_list(struct list_head *head)
+{
+	struct pwrseq *pwrseq;
+	struct pwrseq_list_per_dev *pwrseq_list_node, *tmp_node;
+
+	list_for_each_entry_safe(pwrseq_list_node, tmp_node, head, list) {
+		pwrseq = pwrseq_list_node->pwrseq;
+		of_pwrseq_off(pwrseq);
+		list_del(&pwrseq_list_node->list);
+		kfree(pwrseq_list_node);
+	}
+}
+EXPORT_SYMBOL_GPL(of_pwrseq_off_list);
+
+/**
+ * pwrseq_suspend - Carry out power sequence suspend for this pwrseq instance
+ *
+ * @pwrseq: the pwrseq instance
+ *
+ * This API is used to do suspend operation on pwrseq instance.
+ *
+ * Return 0 on success, or an error value otherwise.
+ */
+int pwrseq_suspend(struct pwrseq *p)
+{
+	int ret = 0;
+
+	if (p && p->suspend)
+		ret = p->suspend(p);
+	else
+		return ret;
+
+	if (!ret)
+		p->suspended = true;
+	else
+		pr_err("%s failed\n", __func__);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_suspend);
+
+/**
+ * pwrseq_resume - Carry out power sequence resume for this pwrseq instance
+ *
+ * @pwrseq: the pwrseq instance
+ *
+ * This API is used to do resume operation on pwrseq instance.
+ *
+ * Return 0 on success, or an error value otherwise.
+ */
+int pwrseq_resume(struct pwrseq *p)
+{
+	int ret = 0;
+
+	if (p && p->resume)
+		ret = p->resume(p);
+	else
+		return ret;
+
+	if (!ret)
+		p->suspended = false;
+	else
+		pr_err("%s failed\n", __func__);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_resume);
+
+/**
+ * pwrseq_suspend_list - Carry out power sequence suspend for list
+ *
+ * @head: the list head for pwrseq instance list on this bus
+ *
+ * This API is used to do suspend on all power sequence instances on this bus.
+ * The caller needs to use mutex_lock for concurrent.
+ */
+int pwrseq_suspend_list(struct list_head *head)
+{
+	struct pwrseq *pwrseq;
+	struct pwrseq_list_per_dev *pwrseq_list_node;
+	int ret = 0;
+
+	list_for_each_entry(pwrseq_list_node, head, list) {
+		ret = pwrseq_suspend(pwrseq_list_node->pwrseq);
+		if (ret)
+			break;
+	}
+
+	if (ret) {
+		list_for_each_entry(pwrseq_list_node, head, list) {
+			pwrseq = pwrseq_list_node->pwrseq;
+			if (pwrseq->suspended)
+				pwrseq_resume(pwrseq);
+		}
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_suspend_list);
+
+/**
+ * pwrseq_resume_list - Carry out power sequence resume for the list
+ *
+ * @head: the list head for pwrseq instance list on this bus
+ *
+ * This API is used to do resume on all power sequence instances on this bus.
+ * The caller needs to use mutex_lock for concurrent.
+ */
+int pwrseq_resume_list(struct list_head *head)
+{
+	struct pwrseq_list_per_dev *pwrseq_list_node;
+	int ret = 0;
+
+	list_for_each_entry(pwrseq_list_node, head, list) {
+		ret = pwrseq_resume(pwrseq_list_node->pwrseq);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(pwrseq_resume_list);

@@ -0,0 +1,234 @@
+/*
+ * pwrseq_generic.c	Generic power sequence handling
+ *
+ * Copyright (C) 2016 Freescale Semiconductor, Inc.
+ * Author: Peter Chen <peter.chen@nxp.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2  of
+ * the License 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <linux/gpio/consumer.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
+#include <linux/slab.h>
+
+#include <linux/power/pwrseq.h>
+
+struct pwrseq_generic {
+	struct pwrseq pwrseq;
+	struct gpio_desc *gpiod_reset;
+	struct clk *clks[PWRSEQ_MAX_CLKS];
+	u32 duration_us;
+	bool suspended;
+};
+
+#define to_generic_pwrseq(p) container_of(p, struct pwrseq_generic, pwrseq)
+
+static int pwrseq_generic_alloc_instance(void);
+static const struct of_device_id generic_id_table[] = {
+	{ .compatible = "generic",},
+	{ /* sentinel */ }
+};
+
+static int pwrseq_generic_suspend(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	for (clk = PWRSEQ_MAX_CLKS - 1; clk >= 0; clk--)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+
+	pwrseq_gen->suspended = true;
+	return 0;
+}
+
+static int pwrseq_generic_resume(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk, ret = 0;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS && pwrseq_gen->clks[clk]; clk++) {
+		ret = clk_prepare_enable(pwrseq_gen->clks[clk]);
+		if (ret) {
+			pr_err("Can't enable clock, ret=%d\n", ret);
+			goto err_disable_clks;
+		}
+	}
+
+	pwrseq_gen->suspended = false;
+	return ret;
+
+err_disable_clks:
+	while (--clk >= 0)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+
+	return ret;
+}
+
+static void pwrseq_generic_put(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	if (pwrseq_gen->gpiod_reset)
+		gpiod_put(pwrseq_gen->gpiod_reset);
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++)
+		clk_put(pwrseq_gen->clks[clk]);
+
+	pwrseq_unregister(&pwrseq_gen->pwrseq);
+	kfree(pwrseq_gen);
+}
+
+static void pwrseq_generic_off(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk;
+
+	if (pwrseq_gen->suspended)
+		return;
+
+	for (clk = PWRSEQ_MAX_CLKS - 1; clk >= 0; clk--)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+}
+
+static int pwrseq_generic_on(struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	int clk, ret = 0;
+	struct gpio_desc *gpiod_reset = pwrseq_gen->gpiod_reset;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS && pwrseq_gen->clks[clk]; clk++) {
+		ret = clk_prepare_enable(pwrseq_gen->clks[clk]);
+		if (ret) {
+			pr_err("Can't enable clock, ret=%d\n", ret);
+			goto err_disable_clks;
+		}
+	}
+
+	if (gpiod_reset) {
+		u32 duration_us = pwrseq_gen->duration_us;
+
+		if (duration_us <= 10)
+			udelay(10);
+		else
+			usleep_range(duration_us, duration_us + 100);
+		gpiod_set_value(gpiod_reset, 0);
+	}
+
+	return ret;
+
+err_disable_clks:
+	while (--clk >= 0)
+		clk_disable_unprepare(pwrseq_gen->clks[clk]);
+
+	return ret;
+}
+
+static int pwrseq_generic_get(struct device_node *np, struct pwrseq *pwrseq)
+{
+	struct pwrseq_generic *pwrseq_gen = to_generic_pwrseq(pwrseq);
+	enum of_gpio_flags flags;
+	int reset_gpio, clk, ret = 0;
+
+	for (clk = 0; clk < PWRSEQ_MAX_CLKS; clk++) {
+		pwrseq_gen->clks[clk] = of_clk_get(np, clk);
+		if (IS_ERR(pwrseq_gen->clks[clk])) {
+			ret = PTR_ERR(pwrseq_gen->clks[clk]);
+			if (ret != -ENOENT)
+				goto err_put_clks;
+			pwrseq_gen->clks[clk] = NULL;
+			break;
+		}
+	}
+
+	reset_gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &flags);
+	if (gpio_is_valid(reset_gpio)) {
+		unsigned long gpio_flags;
+
+		if (flags & OF_GPIO_ACTIVE_LOW)
+			gpio_flags = GPIOF_ACTIVE_LOW | GPIOF_OUT_INIT_LOW;
+		else
+			gpio_flags = GPIOF_OUT_INIT_HIGH;
+
+		ret = gpio_request_one(reset_gpio, gpio_flags,
+				"pwrseq-reset-gpios");
+		if (ret)
+			goto err_put_clks;
+
+		pwrseq_gen->gpiod_reset = gpio_to_desc(reset_gpio);
+		of_property_read_u32(np, "reset-duration-us",
+				&pwrseq_gen->duration_us);
+	} else if (reset_gpio == -ENOENT) {
+		; /* no such gpio */
+	} else {
+		ret = reset_gpio;
+		pr_err("Failed to get reset gpio on %s, err = %d\n",
+				np->full_name, reset_gpio);
+		goto err_put_clks;
+	}
+
+	/* allocate new one for later pwrseq instance request */
+	ret = pwrseq_generic_alloc_instance();
+	if (ret)
+		goto err_put_gpio;
+
+	return 0;
+
+err_put_gpio:
+	if (pwrseq_gen->gpiod_reset)
+		gpiod_put(pwrseq_gen->gpiod_reset);
+err_put_clks:
+	while (--clk >= 0)
+		clk_put(pwrseq_gen->clks[clk]);
+	return ret;
+}
+
+/**
+ * pwrseq_generic_alloc_instance - power sequence instance allocation
+ *
+ * This function is used to allocate one generic power sequence instance,
+ * it is called when the system boots up and after one power sequence
+ * instance is got successfully.
+ *
+ * Return zero on success or an error code otherwise.
+ */
+static int pwrseq_generic_alloc_instance(void)
+{
+	struct pwrseq_generic *pwrseq_gen;
+
+	pwrseq_gen = kzalloc(sizeof(*pwrseq_gen), GFP_KERNEL);
+	if (!pwrseq_gen)
+		return -ENOMEM;
+
+	pwrseq_gen->pwrseq.pwrseq_of_match_table = generic_id_table;
+	pwrseq_gen->pwrseq.get = pwrseq_generic_get;
+	pwrseq_gen->pwrseq.on = pwrseq_generic_on;
+	pwrseq_gen->pwrseq.off = pwrseq_generic_off;
+	pwrseq_gen->pwrseq.put = pwrseq_generic_put;
+	pwrseq_gen->pwrseq.suspend = pwrseq_generic_suspend;
+	pwrseq_gen->pwrseq.resume = pwrseq_generic_resume;
+
+	pwrseq_register(&pwrseq_gen->pwrseq);
+	return 0;
+}
+
+/* Allocate one pwrseq instance during boots up */
+static int __init pwrseq_generic_register(void)
+{
+	return pwrseq_generic_alloc_instance();
+}
+postcore_initcall(pwrseq_generic_register)

@@ -0,0 +1,81 @@
+#ifndef __LINUX_PWRSEQ_H
+#define __LINUX_PWRSEQ_H
+
+#include <linux/of.h>
+
+#define PWRSEQ_MAX_CLKS		3
+
+/**
+ * struct pwrseq - the power sequence structure
+ * @pwrseq_of_match_table: the OF device id table this pwrseq library supports
+ * @node: the list pointer to be added to pwrseq list
+ * @get: the API is used to get pwrseq instance from the device node
+ * @on: do power on for this pwrseq instance
+ * @off: do power off for this pwrseq instance
+ * @put: release the resources on this pwrseq instance
+ * @suspend: do suspend operation on this pwrseq instance
+ * @resume: do resume operation on this pwrseq instance
+ * @used: this pwrseq instance is used by device
+ */
+struct pwrseq {
+	const struct of_device_id *pwrseq_of_match_table;
+	struct list_head node;
+	int (*get)(struct device_node *np, struct pwrseq *p);
+	int (*on)(struct pwrseq *p);
+	void (*off)(struct pwrseq *p);
+	void (*put)(struct pwrseq *p);
+	int (*suspend)(struct pwrseq *p);
+	int (*resume)(struct pwrseq *p);
+	bool used;
+	bool suspended;
+};
+
+/* used for power sequence instance list in one driver */
+struct pwrseq_list_per_dev {
+	struct pwrseq *pwrseq;
+	struct list_head list;
+};
+
+#if IS_ENABLED(CONFIG_POWER_SEQUENCE)
+void pwrseq_register(struct pwrseq *pwrseq);
+void pwrseq_unregister(struct pwrseq *pwrseq);
+struct pwrseq *of_pwrseq_on(struct device_node *np);
+void of_pwrseq_off(struct pwrseq *pwrseq);
+int of_pwrseq_on_list(struct device_node *np, struct list_head *head);
+void of_pwrseq_off_list(struct list_head *head);
+int pwrseq_suspend(struct pwrseq *p);
+int pwrseq_resume(struct pwrseq *p);
+int pwrseq_suspend_list(struct list_head *head);
+int pwrseq_resume_list(struct list_head *head);
+#else
+static inline void pwrseq_register(struct pwrseq *pwrseq) {}
+static inline void pwrseq_unregister(struct pwrseq *pwrseq) {}
+static inline struct pwrseq *of_pwrseq_on(struct device_node *np)
+{
+	return NULL;
+}
+static void of_pwrseq_off(struct pwrseq *pwrseq) {}
+static int of_pwrseq_on_list(struct device_node *np, struct list_head *head)
+{
+	return 0;
+}
+static void of_pwrseq_off_list(struct list_head *head) {}
+static int pwrseq_suspend(struct pwrseq *p)
+{
+	return 0;
+}
+static int pwrseq_resume(struct pwrseq *p)
+{
+	return 0;
+}
+static int pwrseq_suspend_list(struct list_head *head)
+{
+	return 0;
+}
+static int pwrseq_resume_list(struct list_head *head)
+{
+	return 0;
+}
+#endif /* CONFIG_POWER_SEQUENCE */
+
+#endif  /* __LINUX_PWRSEQ_H */