From 1b26d29ccd592ea585c7cc291384184c5568da92 Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Thu, 5 Jul 2012 14:18:21 +0200 Subject: [PATCH] [libata] scsi: implement MODE SELECT command The cache_type file in sysfs lets users configure the disk cache in write-through or write-back modes. However, ata disks do not support writing to the file because they do not implement the MODE SELECT command. This patch adds a translation from MODE SELECT (for the caching page only) to the ATA SET FEATURES command. The set of changeable parameters answered by MODE SENSE is also adjusted accordingly. Signed-off-by: Paolo Bonzini Signed-off-by: Jeff Garzik --- drivers/ata/libata-scsi.c | 194 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 188 insertions(+), 6 deletions(-) diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index 67d23bd87950..e3bda074fa12 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -2243,7 +2243,7 @@ static void modecpy(u8 *dest, const u8 *src, int n, bool changeable) static unsigned int ata_msense_caching(u16 *id, u8 *buf, bool changeable) { modecpy(buf, def_cache_mpage, sizeof(def_cache_mpage), changeable); - if (!changeable && ata_id_wcache_enabled(id)) + if (changeable || ata_id_wcache_enabled(id)) buf[2] |= (1 << 2); /* write cache enable */ if (!changeable && !ata_id_rahead_enabled(id)) buf[12] |= (1 << 5); /* disable read ahead */ @@ -3106,6 +3106,188 @@ static unsigned int ata_scsi_write_same_xlat(struct ata_queued_cmd *qc) return 1; } +/** + * ata_mselect_caching - Simulate MODE SELECT for caching info page + * @qc: Storage for translated ATA taskfile + * @buf: input buffer + * @len: number of valid bytes in the input buffer + * + * Prepare a taskfile to modify caching information for the device. + * + * LOCKING: + * None. + */ +static int ata_mselect_caching(struct ata_queued_cmd *qc, + const u8 *buf, int len) +{ + struct ata_taskfile *tf = &qc->tf; + struct ata_device *dev = qc->dev; + char mpage[CACHE_MPAGE_LEN]; + u8 wce; + + /* + * The first two bytes of def_cache_mpage are a header, so offsets + * in mpage are off by 2 compared to buf. Same for len. + */ + + if (len != CACHE_MPAGE_LEN - 2) + return -EINVAL; + + wce = buf[0] & (1 << 2); + + /* + * Check that read-only bits are not modified. + */ + ata_msense_caching(dev->id, mpage, false); + mpage[2] &= ~(1 << 2); + mpage[2] |= wce; + if (memcmp(mpage + 2, buf, CACHE_MPAGE_LEN - 2) != 0) + return -EINVAL; + + tf->flags |= ATA_TFLAG_DEVICE | ATA_TFLAG_ISADDR; + tf->protocol = ATA_PROT_NODATA; + tf->nsect = 0; + tf->command = ATA_CMD_SET_FEATURES; + tf->feature = wce ? SETFEATURES_WC_ON : SETFEATURES_WC_OFF; + return 0; +} + +/** + * ata_scsiop_mode_select - Simulate MODE SELECT 6, 10 commands + * @qc: Storage for translated ATA taskfile + * + * Converts a MODE SELECT command to an ATA SET FEATURES taskfile. + * Assume this is invoked for direct access devices (e.g. disks) only. + * There should be no block descriptor for other device types. + * + * LOCKING: + * spin_lock_irqsave(host lock) + */ +static unsigned int ata_scsi_mode_select_xlat(struct ata_queued_cmd *qc) +{ + struct scsi_cmnd *scmd = qc->scsicmd; + const u8 *cdb = scmd->cmnd; + const u8 *p; + u8 pg, spg; + unsigned six_byte, pg_len, hdr_len, bd_len; + int len; + + VPRINTK("ENTER\n"); + + six_byte = (cdb[0] == MODE_SELECT); + if (six_byte) { + if (scmd->cmd_len < 5) + goto invalid_fld; + + len = cdb[4]; + hdr_len = 4; + } else { + if (scmd->cmd_len < 9) + goto invalid_fld; + + len = (cdb[7] << 8) + cdb[8]; + hdr_len = 8; + } + + /* We only support PF=1, SP=0. */ + if ((cdb[1] & 0x11) != 0x10) + goto invalid_fld; + + /* Test early for possible overrun. */ + if (!scsi_sg_count(scmd) || scsi_sglist(scmd)->length < len) + goto invalid_param_len; + + p = page_address(sg_page(scsi_sglist(scmd))); + + /* Move past header and block descriptors. */ + if (len < hdr_len) + goto invalid_param_len; + + if (six_byte) + bd_len = p[3]; + else + bd_len = (p[6] << 8) + p[7]; + + len -= hdr_len; + p += hdr_len; + if (len < bd_len) + goto invalid_param_len; + if (bd_len != 0 && bd_len != 8) + goto invalid_param; + + len -= bd_len; + p += bd_len; + if (len == 0) + goto skip; + + /* Parse both possible formats for the mode page headers. */ + pg = p[0] & 0x3f; + if (p[0] & 0x40) { + if (len < 4) + goto invalid_param_len; + + spg = p[1]; + pg_len = (p[2] << 8) | p[3]; + p += 4; + len -= 4; + } else { + if (len < 2) + goto invalid_param_len; + + spg = 0; + pg_len = p[1]; + p += 2; + len -= 2; + } + + /* + * No mode subpages supported (yet) but asking for _all_ + * subpages may be valid + */ + if (spg && (spg != ALL_SUB_MPAGES)) + goto invalid_param; + if (pg_len > len) + goto invalid_param_len; + + switch (pg) { + case CACHE_MPAGE: + if (ata_mselect_caching(qc, p, pg_len) < 0) + goto invalid_param; + break; + + default: /* invalid page code */ + goto invalid_param; + } + + /* + * Only one page has changeable data, so we only support setting one + * page at a time. + */ + if (len > pg_len) + goto invalid_param; + + return 0; + + invalid_fld: + /* "Invalid field in CDB" */ + ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x24, 0x0); + return 1; + + invalid_param: + /* "Invalid field in parameter list" */ + ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x26, 0x0); + return 1; + + invalid_param_len: + /* "Parameter list length error" */ + ata_scsi_set_sense(scmd, ILLEGAL_REQUEST, 0x1a, 0x0); + return 1; + + skip: + scmd->result = SAM_STAT_GOOD; + return 1; +} + /** * ata_get_xlat_func - check if SCSI to ATA translation is possible * @dev: ATA device @@ -3146,6 +3328,11 @@ static inline ata_xlat_func_t ata_get_xlat_func(struct ata_device *dev, u8 cmd) case ATA_16: return ata_scsi_pass_thru; + case MODE_SELECT: + case MODE_SELECT_10: + return ata_scsi_mode_select_xlat; + break; + case START_STOP: return ata_scsi_start_stop_xlat; } @@ -3338,11 +3525,6 @@ void ata_scsi_simulate(struct ata_device *dev, struct scsi_cmnd *cmd) ata_scsi_rbuf_fill(&args, ata_scsiop_mode_sense); break; - case MODE_SELECT: /* unconditionally return */ - case MODE_SELECT_10: /* bad-field-in-cdb */ - ata_scsi_invalid_field(cmd); - break; - case READ_CAPACITY: ata_scsi_rbuf_fill(&args, ata_scsiop_read_cap); break;