build/patch/kernel/imx6-current/0004-usb-core-add-power-sequence-handling-for-USB-devices.patch

From a42362841fe263a6c97a1793ccd4b9246ac2b108 Mon Sep 17 00:00:00 2001
From: Peter Chen <peter.chen@nxp.com>
Date: Thu, 18 May 2017 08:49:00 +0800
Subject: [PATCH 4/9] usb: core: add power sequence handling for USB devices

Some hard-wired USB devices need to do power sequence to let the
device work normally, the typical power sequence like: enable USB
PHY clock, toggle reset pin, etc. But current Linux USB driver
lacks of such code to do it, it may cause some hard-wired USB devices
works abnormal or can't be recognized by controller at all.

In this patch, it calls power sequence library APIs to finish
the power sequence events. It will do power on sequence at hub's
probe for all devices under this hub (includes root hub).
At hub_disconnect, it will do power off sequence which is at powered
on list.

Signed-off-by: Peter Chen <peter.chen@nxp.com>
Tested-by Joshua Clayton <stillcompiling@gmail.com>
Tested-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Reviewed-by: Vaibhav Hiremath <hvaibhav.linux@gmail.com>
---
 drivers/usb/Kconfig    |  1 +
 drivers/usb/core/hub.c | 49 ++++++++++++++++++++++++++++++++++++++----
 drivers/usb/core/hub.h |  1 +
 3 files changed, 47 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/Kconfig b/drivers/usb/Kconfig
index 6e59d370ef81..2162fd85b32d 100644
--- a/drivers/usb/Kconfig
+++ b/drivers/usb/Kconfig
@@ -47,6 +47,7 @@ config USB
 	depends on USB_ARCH_HAS_HCD
 	select GENERIC_ALLOCATOR
 	select USB_COMMON
+	select POWER_SEQUENCE
 	select NLS  # for UTF-8 strings
 	---help---
 	  Universal Serial Bus (USB) is a specification for a serial bus
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 236313f41f4a..3db75b0d2426 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -29,6 +29,7 @@
 #include <linux/random.h>
 #include <linux/pm_qos.h>
 #include <linux/kobject.h>
+#include <linux/power/pwrseq.h>
 
 #include <linux/uaccess.h>
 #include <asm/byteorder.h>
@@ -1705,6 +1706,7 @@ static void hub_disconnect(struct usb_interface *intf)
 	hub->error = 0;
 	hub_quiesce(hub, HUB_DISCONNECT);
 
+	of_pwrseq_off_list(&hub->pwrseq_on_list);
 	mutex_lock(&usb_port_peer_mutex);
 
 	/* Avoid races with recursively_mark_NOTATTACHED() */
@@ -1751,11 +1753,41 @@ static bool hub_descriptor_is_sane(struct usb_host_interface *desc)
         return true;
 }
 
+#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_on_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_device *hdev;
 	struct usb_hub *hub;
+	int ret = -ENODEV;
 
 	desc = intf->cur_altsetting;
 	hdev = interface_to_usbdev(intf);
@@ -1846,6 +1878,7 @@ 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_on_list);
 	spin_lock_init(&hub->irq_urb_lock);
 	timer_setup(&hub->irq_urb_retry, hub_retry_irq_urb, 0);
 	usb_get_intf(intf);
@@ -1861,11 +1894,14 @@ 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, &desc->endpoint[0].desc) >= 0)
-		return 0;
+	if (hub_configure(hub, &desc->endpoint[0].desc) >= 0) {
+		ret = hub_of_pwrseq_on(hub);
+		if (!ret)
+			return 0;
+	}
 
 	hub_disconnect(intf);
-	return -ENODEV;
+	return ret;
 }
 
 static int
@@ -3720,7 +3756,7 @@ 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_on_list);
 }
 
 /* Report wakeup requests from the ports of a resuming root hub */
@@ -3760,8 +3796,13 @@ static void report_wakeup_requests(struct usb_hub *hub)
 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_on_list);
+	if (ret)
+		return ret;
+
 	hub_activate(hub, HUB_RESUME);
 
 	/*
diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h
index a9e24e4b8df1..feab956a1414 100644
--- a/drivers/usb/core/hub.h
+++ b/drivers/usb/core/hub.h
@@ -72,6 +72,7 @@ struct usb_hub {
 	spinlock_t		irq_urb_lock;
 	struct timer_list	irq_urb_retry;
 	struct usb_port		**ports;
+	struct list_head	pwrseq_on_list; /* powered pwrseq node list */
 };
 
 /**
-- 
2.20.1