PCI/ASPM: Handle PCI-to-PCIe bridges as roots of PCIe hierarchies

In a struct pcie_link_state, link->root points to the pcie_link_state of
the root of the PCIe hierarchy.  For the topmost link, this points to
itself (link->root = link).  For others, we copy the pointer from the
parent (link->root = link->parent->root).

Previously we recognized that Root Ports originated PCIe hierarchies, but
we treated PCI/PCI-X to PCIe Bridges as being in the middle of the
hierarchy, and when we tried to copy the pointer from link->parent->root,
there was no parent, and we dereferenced a NULL pointer:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000090
  IP: [<ffffffff9e424350>] pcie_aspm_init_link_state+0x170/0x820

Recognize that PCI/PCI-X to PCIe Bridges originate PCIe hierarchies just
like Root Ports do, so link->root for these devices should also point to
itself.

Fixes: 51ebfc92b72b ("PCI: Enumerate switches below PCI-to-PCIe bridges")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=193411
Link: https://bugzilla.opensuse.org/show_bug.cgi?id=1022181
Tested-by: lists@ssl-mail.com
Tested-by: Jayachandran C. <jnair@caviumnetworks.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v4.2+

path: root/drivers/usb/phy/phy-generic.h

#ifndef _PHY_GENERIC_H_
#define _PHY_GENERIC_H_

#include <linux/usb/usb_phy_generic.h>
#include <linux/gpio/consumer.h>
#include <linux/regulator/consumer.h>

struct usb_phy_generic {
	struct usb_phy phy;
	struct device *dev;
	struct clk *clk;
	struct regulator *vcc;
	struct gpio_desc *gpiod_reset;
	struct gpio_desc *gpiod_vbus;
	struct regulator *vbus_draw;
	bool vbus_draw_enabled;
	unsigned long mA;
	unsigned int vbus;
};

int usb_gen_phy_init(struct usb_phy *phy);
void usb_gen_phy_shutdown(struct usb_phy *phy);

int usb_phy_gen_create_phy(struct device *dev, struct usb_phy_generic *nop,
		struct usb_phy_generic_platform_data *pdata);

#endif