[PATCH] mass storage : emulation of sat scsi_pass_thru with ATACB

[matthieu castet <castet.matthieu@free.fr>]

Hi,

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>

Index: linux-2.6.24.2/drivers/usb/storage/protocol.c
===================================================================
--- linux-2.6.24.2.orig/drivers/usb/storage/protocol.c	2008-02-29 
22:14:09.000000000 +0100
+++ linux-2.6.24.2/drivers/usb/storage/protocol.c	2008-03-08 
18:18:22.000000000 +0100
@@ -47,6 +47,8 @@
  #include <linux/highmem.h>
  #include <scsi/scsi.h>
  #include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_eh.h>
+#include <linux/ata.h>

  #include "usb.h"
  #include "protocol.h"
@@ -144,6 +146,179 @@
  	usb_stor_invoke_transport(srb, us);
  }

+/*
+ * 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.
+ */
+static void emulate_pass_thru_with_atacb(struct scsi_cmnd *srb,
+				       struct us_data *us)
+{
+	unsigned char save_cmnd[MAX_COMMAND_SIZE];
+	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:
+		case 4:
+		case 5:
+			break;
+		default:
+			goto invalid_fld;
+	}
+
+	/* first build the ATACB command */
+	srb->cmd_len = 16;
+
+ 	/* this value can change, but most(all ?) manufacturers keep the cypress
+	 * default : 0x24
+	 */
+	srb->cmnd[0] = 0x24;
+	srb->cmnd[1] = 0x24;
+	srb->cmnd[2] = 0;
+
+	srb->cmnd[3] = 0xff - 1;
+	srb->cmnd[4] = 1;
+
+	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);
+
+
+	usb_stor_invoke_transport(srb, us);
+
+	/* if the device doesn't support ATACB
+	 * abort and register usb_stor_transparent_scsi_command
+	 * callback
+	 */
+	if (srb->result == SAM_STAT_CHECK_CONDITION &&
+			memcmp(srb->sense_buffer, usb_stor_sense_invalidCDB,
+				sizeof(usb_stor_sense_invalidCDB)) == 0) {
+		us->proto_handler = usb_stor_transparent_scsi_command;
+		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 sk, asc, ascq;
+		unsigned char regs[8];
+		unsigned char *sb = srb->sense_buffer;
+		unsigned char *desc = sb + 8;
+		int tmp_result;
+
+		sk = RECOVERED_ERROR;
+		asc = 0; /* ATA PASS THROUGH INFORMATION AVAILABLE */
+		ascq = 0x1D;
+
+		/* read registers */
+		srb->cmnd[2] = 1;
+		scsi_eh_prep_cmnd(srb, &ses, NULL, 0, 0);
+		srb->request_buffer = regs;
+		srb->request_bufflen = sizeof(regs);
+		srb->sc_data_direction = DMA_FROM_DEVICE;
+
+		usb_stor_invoke_transport(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);
+
+		/* 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.
+		 */
+		sb[1] = sk;
+		sb[2] = asc;
+		sb[3] = ascq;
+
+		/* 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];
+		desc[5] = regs[2];
+		desc[7] = regs[3];
+		desc[9] = regs[4];
+		desc[11] = regs[5];
+		desc[12] = regs[6];
+		desc[13] = regs[7];
+
+		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;
+}
+
+void usb_stor_transparent_scsi_command_atacb(struct scsi_cmnd *srb,
+				       struct us_data *us)
+{
+	if (srb->cmnd[0] != ATA_16 && srb->cmnd[0] != ATA_12)
+		usb_stor_invoke_transport(srb, us);
+	else
+		emulate_pass_thru_with_atacb(srb, us);
+}
+
  /***********************************************************************
   * Scatter-gather transfer buffer access routines
   ***********************************************************************/
Index: linux-2.6.24.2/drivers/usb/storage/initializers.c
===================================================================
--- linux-2.6.24.2.orig/drivers/usb/storage/initializers.c	2008-02-29 
22:14:09.000000000 +0100
+++ linux-2.6.24.2/drivers/usb/storage/initializers.c	2008-03-08 
18:30:00.000000000 +0100
@@ -43,6 +43,7 @@
  #include "initializers.h"
  #include "debug.h"
  #include "transport.h"
+#include "protocol.h"

  /* This places the Shuttle/SCM USB<->SCSI bridge devices in multi-target
   * mode */
@@ -104,3 +105,11 @@
  	US_DEBUGP("usb_control_msg performing result is %d\n", result);
  	return (result ? 0 : -1);
  }
+
+/* This function register the atacb proto callback */
+int usb_atacb_init(struct us_data *us)
+{
+	us->proto_handler = usb_stor_transparent_scsi_command_atacb;
+	US_DEBUGP("atacb proto_handler is set\n");
+	return 0;
+}
Index: linux-2.6.24.2/drivers/usb/storage/initializers.h
===================================================================
--- linux-2.6.24.2.orig/drivers/usb/storage/initializers.h	2008-02-29 
22:14:09.000000000 +0100
+++ linux-2.6.24.2/drivers/usb/storage/initializers.h	2008-03-08 
18:28:33.000000000 +0100
@@ -50,3 +50,6 @@

  /* This places the HUAWEI E220 devices in multi-port mode */
  int usb_stor_huawei_e220_init(struct us_data *us);
+
+/* This function register the atacb proto callback */
+int usb_atacb_init(struct us_data *us);
Index: linux-2.6.24.2/drivers/usb/storage/protocol.h
===================================================================
--- linux-2.6.24.2.orig/drivers/usb/storage/protocol.h	2008-02-29 
22:14:09.000000000 +0100
+++ linux-2.6.24.2/drivers/usb/storage/protocol.h	2008-02-29 
22:16:03.000000000 +0100
@@ -47,6 +47,8 @@
  extern void usb_stor_ufi_command(struct scsi_cmnd*, struct us_data*);
  extern void usb_stor_transparent_scsi_command(struct scsi_cmnd*,
  		struct us_data*);
+extern void usb_stor_transparent_scsi_command_atacb(struct scsi_cmnd*,
+		struct us_data*);

  /* struct scsi_cmnd transfer buffer access utilities */
  enum xfer_buf_dir	{TO_XFER_BUF, FROM_XFER_BUF};
Index: linux-2.6.24.2/drivers/usb/storage/unusual_devs.h
===================================================================
--- linux-2.6.24.2.orig/drivers/usb/storage/unusual_devs.h	2008-02-29 
22:14:09.000000000 +0100
+++ linux-2.6.24.2/drivers/usb/storage/unusual_devs.h	2008-02-29 
22:16:03.000000000 +0100
@@ -1588,6 +1588,12 @@
  		US_SC_DEVICE, US_PR_DEVICE, NULL,
  		US_FL_CAPACITY_HEURISTICS),

+UNUSUAL_DEV(  0x04b4, 0x6830, 0x0000, 0x9999,
+		"Cypress",
+		"Cypress AT2LP",
+		US_SC_SCSI, US_PR_BULK, usb_atacb_init,
+		US_FL_NEED_OVERRIDE),
+
  /* Control/Bulk transport for all SubClass values */
  USUAL_DEV(US_SC_RBC, US_PR_CB, USB_US_TYPE_STOR),
  USUAL_DEV(US_SC_8020, US_PR_CB, USB_US_TYPE_STOR),