}
EXPORT_SYMBOL(scsi_report_opcode);
+#define SCSI_CDL_CHECK_BUF_LEN 64
+
+static bool scsi_cdl_check_cmd(struct scsi_device *sdev, u8 opcode, u16 sa,
+ unsigned char *buf)
+{
+ int ret;
+ u8 cdlp;
+
+ /* Check operation code */
+ ret = scsi_report_opcode(sdev, buf, SCSI_CDL_CHECK_BUF_LEN, opcode, sa);
+ if (ret <= 0)
+ return false;
+
+ if ((buf[1] & 0x03) != 0x03)
+ return false;
+
+ /* See SPC-6, one command format of REPORT SUPPORTED OPERATION CODES */
+ cdlp = (buf[1] & 0x18) >> 3;
+ if (buf[0] & 0x01) {
+ /* rwcdlp == 1 */
+ switch (cdlp) {
+ case 0x01:
+ /* T2A page */
+ return true;
+ case 0x02:
+ /* T2B page */
+ return true;
+ }
+ } else {
+ /* rwcdlp == 0 */
+ switch (cdlp) {
+ case 0x01:
+ /* A page */
+ return true;
+ case 0x02:
+ /* B page */
+ return true;
+ }
+ }
+
+ return false;
+}
+
+/**
+ * scsi_cdl_check - Check if a SCSI device supports Command Duration Limits
+ * @sdev: The device to check
+ */
+void scsi_cdl_check(struct scsi_device *sdev)
+{
+ bool cdl_supported;
+ unsigned char *buf;
+
+ buf = kmalloc(SCSI_CDL_CHECK_BUF_LEN, GFP_KERNEL);
+ if (!buf) {
+ sdev->cdl_supported = 0;
+ return;
+ }
+
+ /* Check support for READ_16, WRITE_16, READ_32 and WRITE_32 commands */
+ cdl_supported =
+ scsi_cdl_check_cmd(sdev, READ_16, 0, buf) ||
+ scsi_cdl_check_cmd(sdev, WRITE_16, 0, buf) ||
+ scsi_cdl_check_cmd(sdev, VARIABLE_LENGTH_CMD, READ_32, buf) ||
+ scsi_cdl_check_cmd(sdev, VARIABLE_LENGTH_CMD, WRITE_32, buf);
+ if (cdl_supported) {
+ /*
+ * We have CDL support: force the use of READ16/WRITE16.
+ * READ32 and WRITE32 will be used for devices that support
+ * the T10_PI_TYPE2_PROTECTION protection type.
+ */
+ sdev->use_16_for_rw = 1;
+ sdev->use_10_for_rw = 0;
+
+ sdev->cdl_supported = 1;
+ } else {
+ sdev->cdl_supported = 0;
+ }
+
+ kfree(buf);
+}
+
/**
* scsi_device_get - get an additional reference to a scsi_device
* @sdev: device to get a reference to