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Commit 1494a1f6 authored by Felipe Balbi's avatar Felipe Balbi
Browse files

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: default avatarFelipe Balbi <balbi@ti.com>
parent 410aee70

Documentation/devicetree/bindings/usb/generic.txt

0 → 100644
+24 −0
Original line number Diff line number Diff line 
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>;

	maximum-speed = "super-speed";

	dr_mode = "otg";

};

drivers/usb/usb-common.c

+38 −11
Original line number Diff line number Diff line
@@ -43,9 +43,7 @@ const char *usb_otg_state_string(enum usb_otg_state state) 
}

EXPORT_SYMBOL_GPL(usb_otg_state_string);



const char *usb_speed_string(enum usb_device_speed speed)

{

	static const char *const names[] = {

static const char *const speed_names[] = {

	[USB_SPEED_UNKNOWN] = "UNKNOWN",

	[USB_SPEED_LOW] = "low-speed",

	[USB_SPEED_FULL] = "full-speed",
@@ -54,9 +52,11 @@ const char *usb_speed_string(enum usb_device_speed speed) 
	[USB_SPEED_SUPER] = "super-speed",

};



	if (speed < 0 || speed >= ARRAY_SIZE(names))

const char *usb_speed_string(enum usb_device_speed speed)

{

	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");

include/linux/usb/of.h

+8 −0
Original line number Diff line number Diff line
@@ -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)