Commit 881a256d authored by Matthew Wilcox's avatar Matthew Wilcox Committed by James Bottomley
Browse files

[SCSI] Add VPD helper 



Based on prior work by Martin Petersen and James Bottomley, this patch
adds a generic helper for retrieving VPD pages from SCSI devices.

Signed-off-by: default avatarMatthew Wilcox <willy@linux.intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent 5fa0ae19

drivers/scsi/scsi.c

+104 −0
Original line number Diff line number Diff line
@@ -966,6 +966,110 @@ int scsi_track_queue_full(struct scsi_device *sdev, int depth) 
}

EXPORT_SYMBOL(scsi_track_queue_full);



/**

 * scsi_vpd_inquiry - Request a device provide us with a VPD page

 * @sdev: The device to ask

 * @buffer: Where to put the result

 * @page: Which Vital Product Data to return

 * @len: The length of the buffer

 *

 * This is an internal helper function.  You probably want to use

 * scsi_get_vpd_page instead.

 *

 * Returns 0 on success or a negative error number.

 */

static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,

							u8 page, unsigned len)

{

	int result;

	unsigned char cmd[16];



	cmd[0] = INQUIRY;

	cmd[1] = 1;		/* EVPD */

	cmd[2] = page;

	cmd[3] = len >> 8;

	cmd[4] = len & 0xff;

	cmd[5] = 0;		/* Control byte */



	/*

	 * I'm not convinced we need to try quite this hard to get VPD, but

	 * all the existing users tried this hard.

	 */

	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,

				  len + 4, NULL, 30 * HZ, 3, NULL);

	if (result)

		return result;



	/* Sanity check that we got the page back that we asked for */

	if (buffer[1] != page)

		return -EIO;



	return 0;

}



/**

 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device

 * @sdev: The device to ask

 * @page: Which Vital Product Data to return

 *

 * SCSI devices may optionally supply Vital Product Data.  Each 'page'

 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).

 * If the device supports this VPD page, this routine returns a pointer

 * to a buffer containing the data from that page.  The caller is

 * responsible for calling kfree() on this pointer when it is no longer

 * needed.  If we cannot retrieve the VPD page this routine returns %NULL.

 */

unsigned char *scsi_get_vpd_page(struct scsi_device *sdev, u8 page)

{

	int i, result;

	unsigned int len;

	unsigned char *buf = kmalloc(259, GFP_KERNEL);



	if (!buf)

		return NULL;



	/* Ask for all the pages supported by this device */

	result = scsi_vpd_inquiry(sdev, buf, 0, 255);

	if (result)

		goto fail;



	/* If the user actually wanted this page, we can skip the rest */

	if (page == 0)

		return buf;



	for (i = 0; i < buf[3]; i++)

		if (buf[i + 4] == page)

			goto found;

	/* The device claims it doesn't support the requested page */

	goto fail;



 found:

	result = scsi_vpd_inquiry(sdev, buf, page, 255);

	if (result)

		goto fail;



	/*

	 * Some pages are longer than 255 bytes.  The actual length of

	 * the page is returned in the header.

	 */

	len = (buf[2] << 8) | buf[3];

	if (len <= 255)

		return buf;



	kfree(buf);

	buf = kmalloc(len + 4, GFP_KERNEL);

	result = scsi_vpd_inquiry(sdev, buf, page, len);

	if (result)

		goto fail;



	return buf;



 fail:

	kfree(buf);

	return NULL;

}

EXPORT_SYMBOL_GPL(scsi_get_vpd_page);



/**

 * scsi_device_get  -  get an additional reference to a scsi_device

 * @sdev:	device to get a reference to

include/scsi/scsi_device.h

+1 −0
Original line number Diff line number Diff line
@@ -340,6 +340,7 @@ extern int scsi_mode_select(struct scsi_device *sdev, int pf, int sp, 
			    struct scsi_sense_hdr *);

extern int scsi_test_unit_ready(struct scsi_device *sdev, int timeout,

				int retries, struct scsi_sense_hdr *sshdr);

extern unsigned char *scsi_get_vpd_page(struct scsi_device *, u8 page);

extern int scsi_device_set_state(struct scsi_device *sdev,

				 enum scsi_device_state state);

extern struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,