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[SCSI] Add a report opcode helper

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The REPORT SUPPORTED OPERATION CODES command can be used to query
whether a given opcode is supported by a device. Add a helper function
that allows us to look up commands.

We only issue RSOC if the device reports compliance with SPC-3 or
later. But to err on the side of caution we disable the command for ATA,
FireWire and USB.

Signed-off-by: Martin K. Petersen <[email protected]>
Acked-by: Mike Snitzer <[email protected]>
Signed-off-by: James Bottomley <[email protected]>
This commit is contained in:
Martin K. Petersen 2012-09-18 12:19:30 -04:00 • committed by James Bottomley
commit 3c6bdaeab4
5 changed files with 53 additions and 0 deletions
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45
drivers/scsi/scsi.c
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@ -55,6 +55,7 @@
#include <linux/cpu.h>
#include <linux/mutex.h>
#include <linux/async.h>
#include <asm/unaligned.h>
#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
@ -1061,6 +1062,50 @@ int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
}
EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
/**
* scsi_report_opcode - Find out if a given command opcode is supported
* @sdev: scsi device to query
* @buffer: scratch buffer (must be at least 20 bytes long)
* @len: length of buffer
* @opcode: opcode for command to look up
*
* Uses the REPORT SUPPORTED OPERATION CODES to look up the given
* opcode. Returns 0 if RSOC fails or if the command opcode is
* unsupported. Returns 1 if the device claims to support the command.
*/
int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
unsigned int len, unsigned char opcode)
{
unsigned char cmd[16];
struct scsi_sense_hdr sshdr;
int result;
if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
return 0;
memset(cmd, 0, 16);
cmd[0] = MAINTENANCE_IN;
cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
cmd[2] = 1; /* One command format */
cmd[3] = opcode;
put_unaligned_be32(len, &cmd[6]);
memset(buffer, 0, len);
result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
&sshdr, 30 * HZ, 3, NULL);
if (result && scsi_sense_valid(&sshdr) &&
sshdr.sense_key == ILLEGAL_REQUEST &&
(sshdr.asc == 0x20 || sshdr.asc == 0x24) && sshdr.ascq == 0x00)
return 0;
if ((buffer[1] & 3) == 3) /* Command supported */
return 1;
return 0;
}
EXPORT_SYMBOL(scsi_report_opcode);
/**
* scsi_device_get - get an additional reference to a scsi_device
* @sdev: device to get a reference to