Hi,
On Tue, Jul 02, 2013 at 10:14:08AM +0200, Sebastian Andrzej Siewior wrote:
> >> This looks tricky. If you copy that property unconditionally than
> >> you will end up with UNKNOWN speed if that property is missing
> >> and no gadget will load, right? If so, maybe a second argument
> >> would be nice
> >
> > UDC should be required to treat UNKOWN as maximum-speed not being
> > passed and, thus, fixing it to the maximum the HW supports.
> >
> >> which would be used as the default speed if none is found in DT.
> >> Unless you want to do that check in each and every driver.
> >
> > I don't mind either way although I find it funny to pass a
> > 'default' argument which just gets returned back to the caller if
> > maximum-speed isn't available.
>
> Yeah. Never mind then.
alright, how about this ? I'll split dr_mode documentation to a separate
patch soon and resend with devicetree-discuss in the loop.
commit fdaf552df41a78241b9369f71dd91e4415414c62
Author: Felipe Balbi <balbi@xxxxxx>
Date: Sun Jun 30 13:56:45 2013 +0300
usb: common: introduce of_usb_get_maximum_speed()
this helper will be used for controllers which
want to work at a lower speed even though they
support higher USB transfer rates.
One such case is Texas Instruments' AM437x
SoC where it uses a USB3 controller without
a USB3 PHY, rendering the controller USB2-only.
Signed-off-by: Felipe Balbi <balbi@xxxxxx>
diff --git a/Documentation/devicetree/bindings/usb/generic.txt b/Documentation/devicetree/bindings/usb/generic.txt
new file mode 100644
index 0000000..623e360
--- /dev/null
+++ b/Documentation/devicetree/bindings/usb/generic.txt
@@ -0,0 +1,25 @@
+Generic USB Properties
+
+Optional properties:
+ - maximum-speed: tells USB controllers we want to work up to a certain
+ speed. Valid arguments are "super-speed", "high-speed",
+ "full-speed" and "low-speed". In case this isn't passed
+ via DT, USB controllers should default to their maximum
+ HW capability.
+ - dr_mode: tells Dual-Role USB controllers that we want to work on a
+ particular mode. Valid arguments are "host",
+ "peripheral" and "otg". In case this attribute isn't
+ passed via DT, USB DRD controllers should default to
+ OTG.
+
+This is an attribute to a USB controller such as:
+
+dwc3@4a030000 {
+ compatible = "synopsys,dwc3";
+ reg = <0x4a030000 0xcfff>;
+ interrupts = <0 92 4>
+ usb-phy = <&usb2_phy>, <&usb3,phy>;
+ tx-fifo-resize;
+ maximum-speed = "super-speed";
+ dr_mode = "otg";
+};
diff --git a/drivers/usb/usb-common.c b/drivers/usb/usb-common.c
index 675384d..d771870 100644
--- a/drivers/usb/usb-common.c
+++ b/drivers/usb/usb-common.c
@@ -43,20 +43,20 @@ const char *usb_otg_state_string(enum usb_otg_state state)
}
EXPORT_SYMBOL_GPL(usb_otg_state_string);
+static const char *const speed_names[] = {
+ [USB_SPEED_UNKNOWN] = "UNKNOWN",
+ [USB_SPEED_LOW] = "low-speed",
+ [USB_SPEED_FULL] = "full-speed",
+ [USB_SPEED_HIGH] = "high-speed",
+ [USB_SPEED_WIRELESS] = "wireless",
+ [USB_SPEED_SUPER] = "super-speed",
+};
+
const char *usb_speed_string(enum usb_device_speed speed)
{
- static const char *const names[] = {
- [USB_SPEED_UNKNOWN] = "UNKNOWN",
- [USB_SPEED_LOW] = "low-speed",
- [USB_SPEED_FULL] = "full-speed",
- [USB_SPEED_HIGH] = "high-speed",
- [USB_SPEED_WIRELESS] = "wireless",
- [USB_SPEED_SUPER] = "super-speed",
- };
-
- if (speed < 0 || speed >= ARRAY_SIZE(names))
+ if (speed < 0 || speed >= ARRAY_SIZE(speed_names))
speed = USB_SPEED_UNKNOWN;
- return names[speed];
+ return speed_names[speed];
}
EXPORT_SYMBOL_GPL(usb_speed_string);
@@ -112,6 +112,33 @@ enum usb_dr_mode of_usb_get_dr_mode(struct device_node *np)
return USB_DR_MODE_UNKNOWN;
}
EXPORT_SYMBOL_GPL(of_usb_get_dr_mode);
+
+/**
+ * of_usb_get_maximum_speed - Get maximum requested speed for a given USB
+ * controller.
+ * @np: Pointer to the given device_node
+ *
+ * The function gets the maximum speed string from property "maximum-speed",
+ * and returns the corresponding enum usb_device_speed.
+ */
+enum usb_device_speed of_usb_get_maximum_speed(struct device_node *np)
+{
+ const char *maximum_speed;
+ int err;
+ int i;
+
+ err = of_property_read_string(np, "maximum-speed", &maximum_speed);
+ if (err < 0)
+ return USB_SPEED_UNKNOWN;
+
+ for (i = 0; i < ARRAY_SIZE(speed_names); i++)
+ if (strcmp(maximum_speed, speed_names[i]) == 0)
+ return i;
+
+ return USB_SPEED_UNKNOWN;
+}
+EXPORT_SYMBOL_GPL(of_usb_get_maximum_speed);
+
#endif
MODULE_LICENSE("GPL");
diff --git a/include/linux/usb/of.h b/include/linux/usb/of.h
index a0ef405..5a7cb9e 100644
--- a/include/linux/usb/of.h
+++ b/include/linux/usb/of.h
@@ -7,16 +7,24 @@
#ifndef __LINUX_USB_OF_H
#define __LINUX_USB_OF_H
+#include <linux/usb/ch9.h>
#include <linux/usb/otg.h>
#include <linux/usb/phy.h>
#if IS_ENABLED(CONFIG_OF)
enum usb_dr_mode of_usb_get_dr_mode(struct device_node *np);
+enum usb_device_speed of_usb_get_maximum_speed(struct device_node *np);
#else
static inline enum usb_dr_mode of_usb_get_dr_mode(struct device_node *np)
{
return USB_DR_MODE_UNKNOWN;
}
+
+static inline enum usb_device_speed
+of_usb_get_maximum_speed(struct device_node *np)
+{
+ return USB_SPEED_UNKNOWN;
+}
#endif
#if IS_ENABLED(CONFIG_OF) && IS_ENABLED(CONFIG_USB_PHY)
--
balbi
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