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>
---
drivers/usb/usb-common.c | 35 +++++++++++++++++++++++++++++++++++
include/linux/usb/of.h | 8 ++++++++
2 files changed, 43 insertions(+)
diff --git a/drivers/usb/usb-common.c b/drivers/usb/usb-common.c
index 675384d..b87f202 100644
--- a/drivers/usb/usb-common.c
+++ b/drivers/usb/usb-common.c
@@ -112,6 +112,41 @@ 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);
+
+static const char *const usb_maximum_speed[] = {
+ [USB_SPEED_UNKNOWN] = "",
+ [USB_SPEED_LOW] = "lowspeed",
+ [USB_SPEED_FULL] = "fullspeed",
+ [USB_SPEED_HIGH] = "highspeed",
+ [USB_SPEED_SUPER] = "superspeed",
+};
+
+/**
+ * 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(usb_maximum_speed); i++)
+ if (strcmp(maximum_speed, usb_maximum_speed[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)
--
1.8.2.1
--
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