USB: mass storage: emulation of sat scsi_pass_thru with ATACB

I have got a cypress usb-ide bridge and I would like to tune or monitor
my disk with tools like hdparm, hddtemp or smartctl.

My controller support a way to send raw ATA command to the disk with
something call atacb (see
http://download.cypress.com.edgesuite.net/design_resources/datasheets/contents/cy7c68300c_8.pdf).

Atacb support can be added for each application, but there is some disadvantages :
- all application need to be patched
- A race is possible if there other accesses, because the emulation can
be split in 2 atacb scsi transactions. One for sending the command, one
for reading the register (if ck_cond is set). 

I have implemented the emulation in usb-storage with a special proto_handler,
and an unsual entry.

Signed-off-by: Matthieu CASTET <castet.matthieu@free.fr>
Signed-off-by: Matthew Dharm <mdharm-usb@one-eyed-alien.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 200 insertions, 0 deletions

diff --git a/drivers/usb/storage/cypress_atacb.c b/drivers/usb/storage/cypress_atacb.c
new file mode 100644
index 00000000000000..d88824b3511c0d
--- /dev/null
+++ b/drivers/usb/storage/cypress_atacb.c
@@ -0,0 +1,200 @@
+/*
+ * Support for emulating SAT (ata pass through) on devices based
+ *       on the Cypress USB/ATA bridge supporting ATACB.
+ *
+ * Copyright (c) 2008 Matthieu Castet (castet.matthieu@free.fr)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <scsi/scsi.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_eh.h>
+#include <linux/ata.h>
+
+#include "usb.h"
+#include "protocol.h"
+#include "scsiglue.h"
+#include "debug.h"
+
+/*
+ * ATACB is a protocol used on cypress usb<->ata bridge to
+ * send raw ATA command over mass storage
+ * There is a ATACB2 protocol that support LBA48 on newer chip.
+ * More info that be found on cy7c68310_8.pdf and cy7c68300c_8.pdf
+ * datasheet from cypress.com.
+ */
+void cypress_atacb_passthrough(struct scsi_cmnd *srb, struct us_data *us)
+{
+	unsigned char save_cmnd[MAX_COMMAND_SIZE];
+
+	if (likely(srb->cmnd[0] != ATA_16 && srb->cmnd[0] != ATA_12)) {
+		usb_stor_transparent_scsi_command(srb, us);
+		return;
+	}
+
+	memcpy(save_cmnd, srb->cmnd, sizeof(save_cmnd));
+	memset(srb->cmnd, 0, sizeof(srb->cmnd));
+
+	/* check if we support the command */
+	if (save_cmnd[1] >> 5) /* MULTIPLE_COUNT */
+		goto invalid_fld;
+	/* check protocol */
+	switch((save_cmnd[1] >> 1) & 0xf) {
+		case 3: /*no DATA */
+		case 4: /* PIO in */
+		case 5: /* PIO out */
+			break;
+		default:
+			goto invalid_fld;
+	}
+
+	/* first build the ATACB command */
+	srb->cmd_len = 16;
+
+	srb->cmnd[0] = 0x24; /* bVSCBSignature : vendor-specific command
+	                        this value can change, but most(all ?) manufacturers
+							keep the cypress default : 0x24 */
+	srb->cmnd[1] = 0x24; /* bVSCBSubCommand : 0x24 for ATACB */
+
+	srb->cmnd[3] = 0xff - 1; /* features, sector count, lba low, lba med
+								lba high, device, command are valid */
+	srb->cmnd[4] = 1; /* TransferBlockCount : 512 */
+
+	if (save_cmnd[0] == ATA_16) {
+		srb->cmnd[ 6] = save_cmnd[ 4]; /* features */
+		srb->cmnd[ 7] = save_cmnd[ 6]; /* sector count */
+		srb->cmnd[ 8] = save_cmnd[ 8]; /* lba low */
+		srb->cmnd[ 9] = save_cmnd[10]; /* lba med */
+		srb->cmnd[10] = save_cmnd[12]; /* lba high */
+		srb->cmnd[11] = save_cmnd[13]; /* device */
+		srb->cmnd[12] = save_cmnd[14]; /* command */
+
+		if (save_cmnd[1] & 0x01) {/* extended bit set for LBA48 */
+			/* this could be supported by atacb2 */
+			if (save_cmnd[3] || save_cmnd[5] || save_cmnd[7] || save_cmnd[9]
+					|| save_cmnd[11])
+				goto invalid_fld;
+		}
+	}
+	else { /* ATA12 */
+		srb->cmnd[ 6] = save_cmnd[3]; /* features */
+		srb->cmnd[ 7] = save_cmnd[4]; /* sector count */
+		srb->cmnd[ 8] = save_cmnd[5]; /* lba low */
+		srb->cmnd[ 9] = save_cmnd[6]; /* lba med */
+		srb->cmnd[10] = save_cmnd[7]; /* lba high */
+		srb->cmnd[11] = save_cmnd[8]; /* device */
+		srb->cmnd[12] = save_cmnd[9]; /* command */
+
+	}
+	/* Filter SET_FEATURES - XFER MODE command */
+	if ((srb->cmnd[12] == ATA_CMD_SET_FEATURES)
+			&& (srb->cmnd[6] == SETFEATURES_XFER))
+		goto invalid_fld;
+
+	if (srb->cmnd[12] == ATA_CMD_ID_ATA || srb->cmnd[12] == ATA_CMD_ID_ATAPI)
+		srb->cmnd[2] |= (1<<7); /* set  IdentifyPacketDevice for these cmds */
+
+
+	usb_stor_transparent_scsi_command(srb, us);
+
+	/* if the device doesn't support ATACB
+	 */
+	if (srb->result == SAM_STAT_CHECK_CONDITION &&
+			memcmp(srb->sense_buffer, usb_stor_sense_invalidCDB,
+				sizeof(usb_stor_sense_invalidCDB)) == 0) {
+		US_DEBUGP("cypress atacb not supported ???\n");
+		goto end;
+	}
+
+	/* if ck_cond flags is set, and there wasn't critical error,
+	 * build the special sense
+	 */
+	if ((srb->result != (DID_ERROR << 16) &&
+				srb->result != (DID_ABORT << 16)) &&
+			save_cmnd[2] & 0x20) {
+		struct scsi_eh_save ses;
+		unsigned char regs[8];
+		unsigned char *sb = srb->sense_buffer;
+		unsigned char *desc = sb + 8;
+		int tmp_result;
+
+		/* build the command for
+		 * reading the ATA registers */
+		scsi_eh_prep_cmnd(srb, &ses, NULL, 0, 0);
+		srb->sdb.length = sizeof(regs);
+		sg_init_one(&ses.sense_sgl, regs, srb->sdb.length);
+		srb->sdb.table.sgl = &ses.sense_sgl;
+		srb->sc_data_direction = DMA_FROM_DEVICE;
+		srb->sdb.table.nents = 1;
+		/* we use the same command as before, but we set
+		 * the read taskfile bit, for not executing atacb command,
+		 * but reading register selected in srb->cmnd[4]
+		 */
+		srb->cmnd[2] = 1;
+
+		usb_stor_transparent_scsi_command(srb, us);
+		tmp_result = srb->result;
+		scsi_eh_restore_cmnd(srb, &ses);
+		/* we fail to get registers, report invalid command */
+		if (tmp_result != SAM_STAT_GOOD)
+			goto invalid_fld;
+
+		/* build the sense */
+		memset(sb, 0, SCSI_SENSE_BUFFERSIZE);
+
+		/* set sk, asc for a good command */
+		sb[1] = RECOVERED_ERROR;
+		sb[2] = 0; /* ATA PASS THROUGH INFORMATION AVAILABLE */
+		sb[3] = 0x1D;
+
+		/* XXX we should generate sk, asc, ascq from status and error
+		 * regs
+		 * (see 11.1 Error translation ­ ATA device error to SCSI error map)
+		 * and ata_to_sense_error from libata.
+		 */
+
+		/* Sense data is current and format is descriptor. */
+		sb[0] = 0x72;
+		desc[0] = 0x09; /* ATA_RETURN_DESCRIPTOR */
+
+		/* set length of additional sense data */
+		sb[7] = 14;
+		desc[1] = 12;
+
+		/* Copy registers into sense buffer. */
+		desc[ 2] = 0x00;
+		desc[ 3] = regs[1];  /* features */
+		desc[ 5] = regs[2];  /* sector count */
+		desc[ 7] = regs[3];  /* lba low */
+		desc[ 9] = regs[4];  /* lba med */
+		desc[11] = regs[5];  /* lba high */
+		desc[12] = regs[6];  /* device */
+		desc[13] = regs[7];  /* command */
+
+		srb->result = (DRIVER_SENSE << 24) | SAM_STAT_CHECK_CONDITION;
+	}
+	goto end;
+invalid_fld:
+	srb->result = (DRIVER_SENSE << 24) | SAM_STAT_CHECK_CONDITION;
+
+	memcpy(srb->sense_buffer,
+			usb_stor_sense_invalidCDB,
+			sizeof(usb_stor_sense_invalidCDB));
+end:
+	memcpy(srb->cmnd, save_cmnd, sizeof(save_cmnd));
+	if (srb->cmnd[0] == ATA_12)
+		srb->cmd_len = 12;
+}