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

[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
......@@ -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
......
......@@ -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,
......
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