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@ti.com>
diff --git a/drivers/usb/usb-common.c b/drivers/usb/usb-common.c
index 675384d..d771870a 100644
--- a/drivers/usb/usb-common.c
+++ b/drivers/usb/usb-common.c
@@ -43,20 +43,20 @@
}
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 @@
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");