diff mbox series

[v6,5/5] drivers: Implement module modaliases for USB

Message ID 20221202224744.1447448-5-allenwebb@google.com (mailing list archive)
State New, archived
Headers show
Series [v6,1/5] module: Add empty modalias sysfs attribute | expand

Commit Message

Allen Webb Dec. 2, 2022, 10:47 p.m. UTC
Add the per-subsystem logic needed to print match-based modaliases to
the USB subsystem, so the modalias sysfs attribute for modules will
function for modules that register USB drivers.

Signed-off-by: Allen Webb <allenwebb@google.com>
---
 drivers/base/Makefile          |   2 +-
 drivers/base/base.h            |   8 +
 drivers/base/mod_devicetable.c | 257 +++++++++++++++++++++++++++++++++
 drivers/usb/core/driver.c      |   2 +
 4 files changed, 268 insertions(+), 1 deletion(-)
 create mode 100644 drivers/base/mod_devicetable.c

Comments

Christophe Leroy Dec. 3, 2022, 6:25 p.m. UTC | #1
Le 02/12/2022 à 23:47, Allen Webb a écrit :
> Add the per-subsystem logic needed to print match-based modaliases to
> the USB subsystem, so the modalias sysfs attribute for modules will
> function for modules that register USB drivers.
> 
> Signed-off-by: Allen Webb <allenwebb@google.com>
> ---
>   drivers/base/Makefile          |   2 +-
>   drivers/base/base.h            |   8 +
>   drivers/base/mod_devicetable.c | 257 +++++++++++++++++++++++++++++++++
>   drivers/usb/core/driver.c      |   2 +
>   4 files changed, 268 insertions(+), 1 deletion(-)
>   create mode 100644 drivers/base/mod_devicetable.c
> 
> diff --git a/drivers/base/Makefile b/drivers/base/Makefile
> index 83217d243c25b..924d46ae987f4 100644
> --- a/drivers/base/Makefile
> +++ b/drivers/base/Makefile
> @@ -15,7 +15,7 @@ obj-y				+= firmware_loader/
>   obj-$(CONFIG_NUMA)	+= node.o
>   obj-$(CONFIG_MEMORY_HOTPLUG) += memory.o
>   ifeq ($(CONFIG_SYSFS),y)
> -obj-$(CONFIG_MODULES)	+= module.o
> +obj-$(CONFIG_MODULES)	+= mod_devicetable.o module.o
>   endif
>   obj-$(CONFIG_SYS_HYPERVISOR) += hypervisor.o
>   obj-$(CONFIG_REGMAP)	+= regmap/
> diff --git a/drivers/base/base.h b/drivers/base/base.h
> index b902d1ecc247f..fec56271104fa 100644
> --- a/drivers/base/base.h
> +++ b/drivers/base/base.h
> @@ -173,6 +173,14 @@ static inline void module_add_driver(struct module *mod,
>   static inline void module_remove_driver(struct device_driver *drv) { }
>   #endif
>   
> +#if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
> +ssize_t usb_drv_to_modalias(struct device_driver *drv, char *buf,
> +			    size_t count);
> +#else
> +static inline ssize_t usb_drv_to_modalias(struct device_driver *drv, char *buf,
> +					  size_t count) { return -EINVAL; }
> +#endif
> +
>   #ifdef CONFIG_DEVTMPFS
>   extern int devtmpfs_init(void);
>   #else
> diff --git a/drivers/base/mod_devicetable.c b/drivers/base/mod_devicetable.c
> new file mode 100644
> index 0000000000000..d7f198aad430f
> --- /dev/null
> +++ b/drivers/base/mod_devicetable.c
> @@ -0,0 +1,257 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * mod_devicetable.c - helpers for displaying modaliases through sysfs.
> + *
> + * This borrows a lot from file2alias.c
> + */
> +
> +#include <linux/device/bus.h>
> +#include <linux/device.h>
> +#include <linux/usb.h>
> +
> +#include "base.h"
> +#include "../usb/core/usb.h"
> +
> +/* Helper macro to add a modalias field to the string buffer associated with
> + * a match id.
> + *
> + * Note that:
> + *   + len should be a ssize_t and is modified in the macro
> + *   + sep should be a string literal and is concatenated as part of a format
> + *     string
> + *   + field is the struct field of the match id
> + */
> +#define ADD(buf, count, len, sep, cond, field)				\
> +do {				                                        \
> +	char *buf_ = buf;						\
> +	size_t count_ = count;                                          \
> +	if (cond)							\
> +		(len) += scnprintf(&buf_[len],				\
> +			count_ - (len),					\
> +			sizeof(field) == 1 ? (sep "%02X") :		\
> +			sizeof(field) == 2 ? (sep "%04X") :		\
> +			sizeof(field) == 4 ? (sep "%08X") : "",		\
> +			(field));					\
> +	else								\
> +		(len) += scnprintf(&buf_[len], count_ - (len), (sep "*")); \
> +} while (0)

I think it would be better in your macro returns the updated len instead 
of updating it in place.

> +
> +#ifdef CONFIG_USB
> +/* USB related modaliases can be split because of device number matching, so
> + * this function handles individual modaliases for one segment of the range.
> + */
> +static ssize_t usb_id_to_modalias(const struct usb_device_id *id,
> +				  unsigned int bcdDevice_initial,

No camelCase please.

See https://docs.kernel.org/process/coding-style.html#naming

> +				  int bcdDevice_initial_digits,
> +				  unsigned char range_lo,
> +				  unsigned char range_hi,
> +				  unsigned char max, const char *mod_name,
> +				  char *buf, size_t count)
> +{
> +	ssize_t len = 0;
> +
> +	ADD(buf, count, len, "alias usb:v",
> +	    id->match_flags & USB_DEVICE_ID_MATCH_VENDOR, id->idVendor);
> +	ADD(buf, count, len, "p", id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT,
> +	    id->idProduct);
> +
> +	len += scnprintf(&buf[len], count - len, "d");
> +	if (bcdDevice_initial_digits)
> +		len += scnprintf(&buf[len], count - len, "%0*X",
> +			bcdDevice_initial_digits, bcdDevice_initial);
> +	if (range_lo == range_hi) {
> +		len += scnprintf(&buf[len], count - len, "%X", range_lo);
> +	} else if (range_lo > 0 || range_hi < max) {
> +		if (range_lo > 0x9 || range_hi < 0xA) {
> +			len += scnprintf(&buf[len], count - len, "[%X-%X]",
> +					 range_lo, range_hi);
> +		} else {
> +			len += scnprintf(&buf[len], count - len,
> +				range_lo < 0x9 ? "[%X-9" : "[%X",
> +				range_lo);

Can it fit on 2 lines ?

> +			len += scnprintf(&buf[len], count - len,
> +				range_hi > 0xA ? "A-%X]" : "%X]",
> +				range_hi);

Same ?

> +		}
> +	}
> +	if (bcdDevice_initial_digits < (sizeof(id->bcdDevice_lo) * 2 - 1))
> +		len += scnprintf(&buf[len], count - len, "*");
> +
> +	ADD(buf, count, len, "dc",
> +	    id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS, id->bDeviceClass);
> +	ADD(buf, count, len, "dsc",
> +	    id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS,
> +	    id->bDeviceSubClass);
> +	ADD(buf, count, len, "dp",
> +	    id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL,
> +	    id->bDeviceProtocol);
> +	ADD(buf, count, len, "ic",
> +	    id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS,
> +	    id->bInterfaceClass);
> +	ADD(buf, count, len, "isc",
> +	    id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS,
> +	    id->bInterfaceSubClass);
> +	ADD(buf, count, len, "ip",
> +	    id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL,
> +	    id->bInterfaceProtocol);
> +	ADD(buf, count, len, "in",
> +	    id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER,
> +	    id->bInterfaceNumber);
> +
> +	len += scnprintf(&buf[len], count - len, " %s\n", mod_name);
> +	return len;
> +}
> +
> +/* Handles increment/decrement of BCD formatted integers */
> +/* Returns the previous value, so it works like i++ or i-- */
> +static unsigned int incbcd(unsigned int *bcd,
> +			   int inc,
> +			   unsigned char max,
> +			   size_t chars)
> +{
> +	unsigned int init = *bcd, i, j;
> +	unsigned long long c, dec = 0, div;

Can you simplify this function with helpers from include/linux/bcd.h ?

> +
> +	/* If bcd is not in BCD format, just increment */
> +	if (max > 0x9) {
> +		*bcd += inc;
> +		return init;
> +	}
> +
> +	/* Convert BCD to Decimal */
> +	for (i = 0 ; i < chars ; i++) {
> +		c = (*bcd >> (i << 2)) & 0xf;
> +		c = c > 9 ? 9 : c; /* force to bcd just in case */
> +		for (j = 0 ; j < i ; j++)
> +			c = c * 10;
> +		dec += c;
> +	}
> +
> +	/* Do our increment/decrement */
> +	dec += inc;
> +	*bcd  = 0;
> +
> +	/* Convert back to BCD */
> +	for (i = 0 ; i < chars ; i++) {
> +		for (c = 1, j = 0 ; j < i ; j++)
> +			c = c * 10;
> +		div = dec;
> +		(void)do_div(div, c); /* div = div / c */
> +		c = do_div(div, 10); /* c = div % 10; div = div / 10 */
> +		*bcd += c << (i << 2);
> +	}
> +	return init;
> +}
> +
> +/* Print the modaliases for the specified struct usb_device_id. */
> +static ssize_t usb_id_to_modalias_multi(const struct usb_device_id *id,
> +					const char *mod_name, char *buf,
> +					size_t count)
> +{
> +	ssize_t len = 0;
> +	unsigned int devlo, devhi;
> +	unsigned char chi, clo, max;
> +	int ndigits;
> +
> +	devlo = id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO ?
> +		id->bcdDevice_lo : 0x0U;
> +	devhi = id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI ?
> +		id->bcdDevice_hi : ~0x0U;
> +
> +	/* Figure out if this entry is in bcd or hex format */
> +	max = 0x9; /* Default to decimal format */
> +	for (ndigits = 0 ; ndigits < sizeof(id->bcdDevice_lo) * 2 ; ndigits++) {
> +		clo = (devlo >> (ndigits << 2)) & 0xf;
> +		chi = ((devhi > 0x9999 ? 0x9999 : devhi) >>
> +		       (ndigits << 2)) & 0xf;
> +		if (clo > max || chi > max) {
> +			max = 0xf;
> +			break;
> +		}
> +	}
> +
> +	/*
> +	 * Some modules (visor) have empty slots as placeholder for
> +	 * run-time specification that results in catch-all alias
> +	 */
> +	if (!(id->idVendor || id->idProduct || id->bDeviceClass ||
> +	      id->bInterfaceClass))
> +		return len;
> +
> +	/* Convert numeric bcdDevice range into fnmatch-able pattern(s) */
> +	for (ndigits = sizeof(id->bcdDevice_lo) * 2 - 1; devlo <= devhi;
> +	     ndigits--) {
> +		clo = devlo & 0xf;
> +		chi = devhi & 0xf;
> +		/* If we are in bcd mode, truncate if necessary */
> +		if (chi > max)
> +			chi = max;
> +		devlo >>= 4;
> +		devhi >>= 4;
> +
> +		if (devlo == devhi || !ndigits) {
> +			len += usb_id_to_modalias(id, devlo, ndigits, clo, chi,
> +						  max, mod_name, buf + len,
> +						  count - len);
> +			break;
> +		}
> +
> +		if (clo > 0x0)
> +			len += usb_id_to_modalias(id,
> +				incbcd(&devlo, 1, max,
> +				       sizeof(id->bcdDevice_lo) * 2),
> +				ndigits, clo, max, max, mod_name, buf + len,
> +				count - len);
> +
> +		if (chi < max)
> +			len += usb_id_to_modalias(id,
> +				incbcd(&devhi, -1, max,
> +				       sizeof(id->bcdDevice_lo) * 2),
> +				ndigits, 0x0, chi, max, mod_name, buf + len,
> +				count - len);
> +	}
> +	return len;
> +}
> +
> +/* Print the modaliases for the given driver assumed to be an usb_driver or
> + * usb_device_driver.
> + *
> + * "alias" is prepended and the module name is appended to each modalias to
> + * match the format in modules.aliases.
> + *
> + * The modaliases will be written out to @buf with @count being the maximum
> + * bytes to write. The return value is a negative errno on error or the number
> + * of bytes written to @buf on success.
> + */
> +ssize_t usb_drv_to_modalias(struct device_driver *drv, char *buf,
> +			    size_t count)
> +{
> +	ssize_t len = 0;
> +	const struct usb_device_id *id;
> +	const char *mod_name;
> +
> +	if (drv->bus != &usb_bus_type)
> +		return -EINVAL;
> +
> +	if (drv->owner)
> +		mod_name = drv->owner->name;
> +	else
> +		mod_name = drv->mod_name;
> +
> +	if (is_usb_device_driver(drv))
> +		id = to_usb_device_driver(drv)->id_table;
> +	else
> +		id = to_usb_driver(drv)->id_table;
> +	if (!id)
> +		return len;

Would be more explicit to return 0;

> +
> +	for (; id->match_flags; id++) {
> +		len += usb_id_to_modalias_multi(id, mod_name, buf + len,
> +						count - len);
> +	}
> +	return len;
> +}
> +#else
> +inline ssize_t usb_drv_to_modalias(struct device_driver *drv, char *buf,
> +				   size_t count){ return 0; }

Why inline ? How can that work ?

> +#endif
> diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
> index 7e7e119c253fb..fdbc197b64c9c 100644
> --- a/drivers/usb/core/driver.c
> +++ b/drivers/usb/core/driver.c
> @@ -32,6 +32,7 @@
>   #include <linux/usb/quirks.h>
>   #include <linux/usb/hcd.h>
>   
> +#include "../../base/base.h"
>   #include "usb.h"
>   
>   
> @@ -2030,4 +2031,5 @@ struct bus_type usb_bus_type = {
>   	.match =	usb_device_match,
>   	.uevent =	usb_uevent,
>   	.need_parent_lock =	true,
> +	.drv_to_modalias = usb_drv_to_modalias,
>   };

As far as I can see, usb_drv_to_modalias() is never called outside this 
file, so it shouldn't be defined in a .h and it should be static.
Greg Kroah-Hartman Dec. 4, 2022, 8:27 a.m. UTC | #2
On Sat, Dec 03, 2022 at 06:25:46PM +0000, Christophe Leroy wrote:
> > +
> > +#ifdef CONFIG_USB
> > +/* USB related modaliases can be split because of device number matching, so
> > + * this function handles individual modaliases for one segment of the range.
> > + */
> > +static ssize_t usb_id_to_modalias(const struct usb_device_id *id,
> > +				  unsigned int bcdDevice_initial,
> 
> No camelCase please.
> 
> See https://docs.kernel.org/process/coding-style.html#naming

This is a name that comes directly from the USB specification, and as
such, those usages of CamelCase are allowed as they refer to well-known
fields.

But, the field is called bcdDevice, not bcdDevice_initial, so this could
get a better name overall as it doesn't directly match up, so it should
be changed to something a bit nicer.

thanks,

greg k-h
Greg Kroah-Hartman Dec. 5, 2022, 3:53 p.m. UTC | #3
On Fri, Dec 02, 2022 at 04:47:44PM -0600, Allen Webb wrote:
> Add the per-subsystem logic needed to print match-based modaliases to
> the USB subsystem, so the modalias sysfs attribute for modules will
> function for modules that register USB drivers.
> 
> Signed-off-by: Allen Webb <allenwebb@google.com>
> ---
>  drivers/base/Makefile          |   2 +-
>  drivers/base/base.h            |   8 +
>  drivers/base/mod_devicetable.c | 257 +++++++++++++++++++++++++++++++++
>  drivers/usb/core/driver.c      |   2 +

It feels like you have a lot of USB-specific stuff here in the driver
core, and not enough in the usb core.  How is each different bus going
to do this?  Add code to the driver core?  It should be able to not
touch the driver core at all to add support for this for a new bus.

thanks,

greg k-h
diff mbox series

Patch

diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index 83217d243c25b..924d46ae987f4 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -15,7 +15,7 @@  obj-y				+= firmware_loader/
 obj-$(CONFIG_NUMA)	+= node.o
 obj-$(CONFIG_MEMORY_HOTPLUG) += memory.o
 ifeq ($(CONFIG_SYSFS),y)
-obj-$(CONFIG_MODULES)	+= module.o
+obj-$(CONFIG_MODULES)	+= mod_devicetable.o module.o
 endif
 obj-$(CONFIG_SYS_HYPERVISOR) += hypervisor.o
 obj-$(CONFIG_REGMAP)	+= regmap/
diff --git a/drivers/base/base.h b/drivers/base/base.h
index b902d1ecc247f..fec56271104fa 100644
--- a/drivers/base/base.h
+++ b/drivers/base/base.h
@@ -173,6 +173,14 @@  static inline void module_add_driver(struct module *mod,
 static inline void module_remove_driver(struct device_driver *drv) { }
 #endif
 
+#if defined(CONFIG_SYSFS) && defined(CONFIG_MODULES)
+ssize_t usb_drv_to_modalias(struct device_driver *drv, char *buf,
+			    size_t count);
+#else
+static inline ssize_t usb_drv_to_modalias(struct device_driver *drv, char *buf,
+					  size_t count) { return -EINVAL; }
+#endif
+
 #ifdef CONFIG_DEVTMPFS
 extern int devtmpfs_init(void);
 #else
diff --git a/drivers/base/mod_devicetable.c b/drivers/base/mod_devicetable.c
new file mode 100644
index 0000000000000..d7f198aad430f
--- /dev/null
+++ b/drivers/base/mod_devicetable.c
@@ -0,0 +1,257 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * mod_devicetable.c - helpers for displaying modaliases through sysfs.
+ *
+ * This borrows a lot from file2alias.c
+ */
+
+#include <linux/device/bus.h>
+#include <linux/device.h>
+#include <linux/usb.h>
+
+#include "base.h"
+#include "../usb/core/usb.h"
+
+/* Helper macro to add a modalias field to the string buffer associated with
+ * a match id.
+ *
+ * Note that:
+ *   + len should be a ssize_t and is modified in the macro
+ *   + sep should be a string literal and is concatenated as part of a format
+ *     string
+ *   + field is the struct field of the match id
+ */
+#define ADD(buf, count, len, sep, cond, field)				\
+do {				                                        \
+	char *buf_ = buf;						\
+	size_t count_ = count;                                          \
+	if (cond)							\
+		(len) += scnprintf(&buf_[len],				\
+			count_ - (len),					\
+			sizeof(field) == 1 ? (sep "%02X") :		\
+			sizeof(field) == 2 ? (sep "%04X") :		\
+			sizeof(field) == 4 ? (sep "%08X") : "",		\
+			(field));					\
+	else								\
+		(len) += scnprintf(&buf_[len], count_ - (len), (sep "*")); \
+} while (0)
+
+#ifdef CONFIG_USB
+/* USB related modaliases can be split because of device number matching, so
+ * this function handles individual modaliases for one segment of the range.
+ */
+static ssize_t usb_id_to_modalias(const struct usb_device_id *id,
+				  unsigned int bcdDevice_initial,
+				  int bcdDevice_initial_digits,
+				  unsigned char range_lo,
+				  unsigned char range_hi,
+				  unsigned char max, const char *mod_name,
+				  char *buf, size_t count)
+{
+	ssize_t len = 0;
+
+	ADD(buf, count, len, "alias usb:v",
+	    id->match_flags & USB_DEVICE_ID_MATCH_VENDOR, id->idVendor);
+	ADD(buf, count, len, "p", id->match_flags & USB_DEVICE_ID_MATCH_PRODUCT,
+	    id->idProduct);
+
+	len += scnprintf(&buf[len], count - len, "d");
+	if (bcdDevice_initial_digits)
+		len += scnprintf(&buf[len], count - len, "%0*X",
+			bcdDevice_initial_digits, bcdDevice_initial);
+	if (range_lo == range_hi) {
+		len += scnprintf(&buf[len], count - len, "%X", range_lo);
+	} else if (range_lo > 0 || range_hi < max) {
+		if (range_lo > 0x9 || range_hi < 0xA) {
+			len += scnprintf(&buf[len], count - len, "[%X-%X]",
+					 range_lo, range_hi);
+		} else {
+			len += scnprintf(&buf[len], count - len,
+				range_lo < 0x9 ? "[%X-9" : "[%X",
+				range_lo);
+			len += scnprintf(&buf[len], count - len,
+				range_hi > 0xA ? "A-%X]" : "%X]",
+				range_hi);
+		}
+	}
+	if (bcdDevice_initial_digits < (sizeof(id->bcdDevice_lo) * 2 - 1))
+		len += scnprintf(&buf[len], count - len, "*");
+
+	ADD(buf, count, len, "dc",
+	    id->match_flags & USB_DEVICE_ID_MATCH_DEV_CLASS, id->bDeviceClass);
+	ADD(buf, count, len, "dsc",
+	    id->match_flags & USB_DEVICE_ID_MATCH_DEV_SUBCLASS,
+	    id->bDeviceSubClass);
+	ADD(buf, count, len, "dp",
+	    id->match_flags & USB_DEVICE_ID_MATCH_DEV_PROTOCOL,
+	    id->bDeviceProtocol);
+	ADD(buf, count, len, "ic",
+	    id->match_flags & USB_DEVICE_ID_MATCH_INT_CLASS,
+	    id->bInterfaceClass);
+	ADD(buf, count, len, "isc",
+	    id->match_flags & USB_DEVICE_ID_MATCH_INT_SUBCLASS,
+	    id->bInterfaceSubClass);
+	ADD(buf, count, len, "ip",
+	    id->match_flags & USB_DEVICE_ID_MATCH_INT_PROTOCOL,
+	    id->bInterfaceProtocol);
+	ADD(buf, count, len, "in",
+	    id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER,
+	    id->bInterfaceNumber);
+
+	len += scnprintf(&buf[len], count - len, " %s\n", mod_name);
+	return len;
+}
+
+/* Handles increment/decrement of BCD formatted integers */
+/* Returns the previous value, so it works like i++ or i-- */
+static unsigned int incbcd(unsigned int *bcd,
+			   int inc,
+			   unsigned char max,
+			   size_t chars)
+{
+	unsigned int init = *bcd, i, j;
+	unsigned long long c, dec = 0, div;
+
+	/* If bcd is not in BCD format, just increment */
+	if (max > 0x9) {
+		*bcd += inc;
+		return init;
+	}
+
+	/* Convert BCD to Decimal */
+	for (i = 0 ; i < chars ; i++) {
+		c = (*bcd >> (i << 2)) & 0xf;
+		c = c > 9 ? 9 : c; /* force to bcd just in case */
+		for (j = 0 ; j < i ; j++)
+			c = c * 10;
+		dec += c;
+	}
+
+	/* Do our increment/decrement */
+	dec += inc;
+	*bcd  = 0;
+
+	/* Convert back to BCD */
+	for (i = 0 ; i < chars ; i++) {
+		for (c = 1, j = 0 ; j < i ; j++)
+			c = c * 10;
+		div = dec;
+		(void)do_div(div, c); /* div = div / c */
+		c = do_div(div, 10); /* c = div % 10; div = div / 10 */
+		*bcd += c << (i << 2);
+	}
+	return init;
+}
+
+/* Print the modaliases for the specified struct usb_device_id. */
+static ssize_t usb_id_to_modalias_multi(const struct usb_device_id *id,
+					const char *mod_name, char *buf,
+					size_t count)
+{
+	ssize_t len = 0;
+	unsigned int devlo, devhi;
+	unsigned char chi, clo, max;
+	int ndigits;
+
+	devlo = id->match_flags & USB_DEVICE_ID_MATCH_DEV_LO ?
+		id->bcdDevice_lo : 0x0U;
+	devhi = id->match_flags & USB_DEVICE_ID_MATCH_DEV_HI ?
+		id->bcdDevice_hi : ~0x0U;
+
+	/* Figure out if this entry is in bcd or hex format */
+	max = 0x9; /* Default to decimal format */
+	for (ndigits = 0 ; ndigits < sizeof(id->bcdDevice_lo) * 2 ; ndigits++) {
+		clo = (devlo >> (ndigits << 2)) & 0xf;
+		chi = ((devhi > 0x9999 ? 0x9999 : devhi) >>
+		       (ndigits << 2)) & 0xf;
+		if (clo > max || chi > max) {
+			max = 0xf;
+			break;
+		}
+	}
+
+	/*
+	 * Some modules (visor) have empty slots as placeholder for
+	 * run-time specification that results in catch-all alias
+	 */
+	if (!(id->idVendor || id->idProduct || id->bDeviceClass ||
+	      id->bInterfaceClass))
+		return len;
+
+	/* Convert numeric bcdDevice range into fnmatch-able pattern(s) */
+	for (ndigits = sizeof(id->bcdDevice_lo) * 2 - 1; devlo <= devhi;
+	     ndigits--) {
+		clo = devlo & 0xf;
+		chi = devhi & 0xf;
+		/* If we are in bcd mode, truncate if necessary */
+		if (chi > max)
+			chi = max;
+		devlo >>= 4;
+		devhi >>= 4;
+
+		if (devlo == devhi || !ndigits) {
+			len += usb_id_to_modalias(id, devlo, ndigits, clo, chi,
+						  max, mod_name, buf + len,
+						  count - len);
+			break;
+		}
+
+		if (clo > 0x0)
+			len += usb_id_to_modalias(id,
+				incbcd(&devlo, 1, max,
+				       sizeof(id->bcdDevice_lo) * 2),
+				ndigits, clo, max, max, mod_name, buf + len,
+				count - len);
+
+		if (chi < max)
+			len += usb_id_to_modalias(id,
+				incbcd(&devhi, -1, max,
+				       sizeof(id->bcdDevice_lo) * 2),
+				ndigits, 0x0, chi, max, mod_name, buf + len,
+				count - len);
+	}
+	return len;
+}
+
+/* Print the modaliases for the given driver assumed to be an usb_driver or
+ * usb_device_driver.
+ *
+ * "alias" is prepended and the module name is appended to each modalias to
+ * match the format in modules.aliases.
+ *
+ * The modaliases will be written out to @buf with @count being the maximum
+ * bytes to write. The return value is a negative errno on error or the number
+ * of bytes written to @buf on success.
+ */
+ssize_t usb_drv_to_modalias(struct device_driver *drv, char *buf,
+			    size_t count)
+{
+	ssize_t len = 0;
+	const struct usb_device_id *id;
+	const char *mod_name;
+
+	if (drv->bus != &usb_bus_type)
+		return -EINVAL;
+
+	if (drv->owner)
+		mod_name = drv->owner->name;
+	else
+		mod_name = drv->mod_name;
+
+	if (is_usb_device_driver(drv))
+		id = to_usb_device_driver(drv)->id_table;
+	else
+		id = to_usb_driver(drv)->id_table;
+	if (!id)
+		return len;
+
+	for (; id->match_flags; id++) {
+		len += usb_id_to_modalias_multi(id, mod_name, buf + len,
+						count - len);
+	}
+	return len;
+}
+#else
+inline ssize_t usb_drv_to_modalias(struct device_driver *drv, char *buf,
+				   size_t count){ return 0; }
+#endif
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 7e7e119c253fb..fdbc197b64c9c 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -32,6 +32,7 @@ 
 #include <linux/usb/quirks.h>
 #include <linux/usb/hcd.h>
 
+#include "../../base/base.h"
 #include "usb.h"
 
 
@@ -2030,4 +2031,5 @@  struct bus_type usb_bus_type = {
 	.match =	usb_device_match,
 	.uevent =	usb_uevent,
 	.need_parent_lock =	true,
+	.drv_to_modalias = usb_drv_to_modalias,
 };