Matthew Wilcox wrote:
This patch adds partial support for the SCSI commands READ_BUFFER and
WRITE_BUFFER. Because ATA only supports a single 512-byte buffer per
drive, this isn't as useful as it could be, but it might prove interesting
when extended to handle the DOWNLOAD MICROCODE operations.
General concept: ACK
Minor nits below...
diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index 8f0e8f2..f12403f 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -1711,6 +1711,117 @@ void ata_scsi_rbuf_fill(struct ata_scsi_args *args,
args->done(cmd);
}
+/*
+ * This helper is used for three subcommands of READ_BUFFER. Subcommand 0
+ * wants a header prefixing the data. Subcommand 3 returns a descriptor
+ * and subcommand 0xb returns a descriptor for the echo buffer. While these
+ * all have slightly different formats, in practise they all look sufficiently
+ * similar that this common function can be used.
+ */
+static void ata_scsi_fill_buffer_descriptor(struct scsi_cmnd *cmd, int desc)
+{
+ u8 *rbuf;
+ unsigned int buflen;
+ unsigned long flags;
+
+ local_irq_save(flags);
+
+ buflen = ata_scsi_rbuf_get(cmd, &rbuf);
+
+ memset(rbuf, 0, buflen);
+ rbuf[0] = desc ? 0xff : 0x0;
+ rbuf[1] = 0x0;
+ rbuf[2] = 0x2;
+ rbuf[3] = 0x0;
+
+ ata_scsi_rbuf_put(cmd, rbuf);
+
+ local_irq_restore(flags);
+}
use ata_scsi_rbuf_fill() rather than recreating it manually
+static int ata_scsi_read_buffer_descriptor(struct scsi_cmnd *cmd)
+{
+ ata_scsi_fill_buffer_descriptor(cmd, cmd->cmnd[1] == 0x3);
+
+ cmd->result = SAM_STAT_GOOD;
+ return 1;
+}
+
+static void ata_scsi_rwbuf_header(struct scsi_cmnd *cmd)
+{
+ struct scatterlist *sg = scsi_sglist(cmd);
+ ata_scsi_fill_buffer_descriptor(cmd, 0);
+
+ /* XXX: fewer than 4 bytes in the page? Doomed. */
+ sg->offset += 4;
+ sg->length -= 4;
I'm quite uncomfortable skipping any amount of validation.
+/**
+ * ata_scsi_rwbuf_xlat - Translate READ_BUFFER and WRITE_BUFFER
+ *
+ * SCSI has a very flexible READ_BUFFER and WRITE_BUFFER system.
+ * ATA's READ BUFFER only supports an offset of 0 and length 512.
+ * SCSI also uses WRITE_BUFFER for DOWNLOAD MICROCODE, which is not
+ * yet supported by this function.
+ */
+static unsigned int ata_scsi_rwbuf_xlat(struct ata_queued_cmd *qc)
+{
+ struct scsi_cmnd *scmd = qc->scsicmd;
+ const u8 *cdb = scmd->cmnd;
+ struct ata_taskfile *tf = &qc->tf;
+ int offset = 0;
+
+ if (cdb[0] == WRITE_BUFFER) {
+ tf->flags |= ATA_TFLAG_WRITE;
+ tf->command = ATA_CMD_WRITE_BUFFER;
+ } else {
+ tf->command = ATA_CMD_READ_BUFFER;
+ }
+
+ switch (cdb[1]) {
+ case 0x0: /* Read/write data with header */
+ ata_scsi_rwbuf_header(scmd);
+ offset = 4;
+ case 0x2: /* Read/write data */
+ case 0xa: /* Read/write echo buffer */
+ break;
+ case 0x3: /* Read descriptor */
+ case 0xb: /* Read echo buffer descriptor */
+ if (cdb[0] == READ_BUFFER)
+ return ata_scsi_read_buffer_descriptor(scmd);
+ case 0x4:
+ case 0x5:
+ case 0x6:
+ case 0x7:
+ /* XXX: We can translate to DOWNLOAD_MICROCODE here */
Style in libata is "FIXME" or "TODO" not "XXX". Please help with
consistency, it makes grepping easier.
Plus, I dunno about you, but I'm not a porn star :)
Jeff
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