USB: powerpc: Workaround for the PPC440EPX USBH_23 errata [take 3]

A published errata for ppc440epx states, that when running Linux with
both EHCI and OHCI modules loaded, the EHCI module experiences a fatal
error when a high-speed device is connected to the USB2.0, and
functions normally if OHCI module is not loaded.

There used to be recommendation to use only hi-speed or full-speed
devices with specific conditions, when respective module was unloaded.
Later, it was observed that ohci suspend is enough to keep things
going, and it was turned into workaround, as explained below.

Quote from original descriprion:

The 440EPx USB 2.0 Host controller is an EHCI compliant controller.  In
USB 2.0 Host controllers, each EHCI controller has one or more companion
controllers, which may be OHCI or UHCI.  An USB 2.0 Host controller will
contain one or more ports.  For each port, only one of the controllers
is connected at any one time. In the 440EPx, there is only one OHCI
companion controller, and only one USB 2.0 Host port.
All ports on an USB 2.0 controller default to the companion
controller.  If you load only an ohci driver, it will have control of
the ports and any deviceplugged in will operate, although high speed
devices will be forced to operate at full speed.  When an ehci driver
is loaded, it explicitly takes control of the ports.  If there is a
device connected, and / or every time there is a new device connected,
the ehci driver determines if the device is high speed or not.  If it
is high speed, the driver retains control of the port.  If it is not,
the driver explicitly gives the companion controller control of the
port.

The is a software workaround that uses
Initial version of the software workaround was posted to
linux-usb-devel:

http://www.mail-archive.com/linux-usb-devel@lists.sourceforge.net/msg54019.html

and later available from amcc.com:
http://www.amcc.com/Embedded/Downloads/download.html?cat=1&family=15&ins=2

The patch below is generally based on the latter, but reworked to
powerpc/of_device USB drivers, and uses a few devicetree inquiries to
get rid of (some) hardcoded defines.

Signed-off-by: Vitaly Bordug <vitb@kernel.crashing.org>
Signed-off-by: Stefan Roese <sr@denx.de>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 34 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci.h b/drivers/usb/host/ehci.h
index c7d4b5a06bdb..fb7054ccf4fc 100644
--- a/drivers/usb/host/ehci.h
+++ b/drivers/usb/host/ehci.h
@@ -120,6 +120,16 @@ struct ehci_hcd {			/* one per controller */
 	unsigned		has_fsl_port_bug:1; /* FreeScale */
 	unsigned		big_endian_mmio:1;
 	unsigned		big_endian_desc:1;
+	unsigned		has_amcc_usb23:1;
+
+	/* required for usb32 quirk */
+	#define OHCI_CTRL_HCFS          (3 << 6)
+	#define OHCI_USB_OPER           (2 << 6)
+	#define OHCI_USB_SUSPEND        (3 << 6)
+
+	#define OHCI_HCCTRL_OFFSET      0x4
+	#define OHCI_HCCTRL_LEN         0x4
+	__hc32			*ohci_hcctrl_reg;
 
 	u8			sbrn;		/* packed release number */
 
@@ -636,6 +646,30 @@ static inline void ehci_writel(const struct ehci_hcd *ehci,
 #endif
 }
 
+/*
+ * On certain ppc-44x SoC there is a HW issue, that could only worked around with
+ * explicit suspend/operate of OHCI. This function hereby makes sense only on that arch.
+ * Other common bits are dependant on has_amcc_usb23 quirk flag.
+ */
+#ifdef CONFIG_44x
+static inline void set_ohci_hcfs(struct ehci_hcd *ehci, int operational)
+{
+	u32 hc_control;
+
+	hc_control = (readl_be(ehci->ohci_hcctrl_reg) & ~OHCI_CTRL_HCFS);
+	if (operational)
+		hc_control |= OHCI_USB_OPER;
+	else
+		hc_control |= OHCI_USB_SUSPEND;
+
+	writel_be(hc_control, ehci->ohci_hcctrl_reg);
+	(void) readl_be(ehci->ohci_hcctrl_reg);
+}
+#else
+static inline void set_ohci_hcfs(struct ehci_hcd *ehci, int operational)
+{ }
+#endif
+
 /*-------------------------------------------------------------------------*/
 
 /*