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

From: Matthew Dharm
Date: Sat Mar 08 2008 - 13:31:48 EST

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In reply to: matthieu castet: "[PATCH] mass storage : emulation of sat scsi_pass_thru with ATACB"
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Why are you using an initializer instead of a new protocol code?

Most of this should probably be moved into it's own file, just like all of
the other protocol handlers.

Actually, why do you even have a separate 'dispatcher' function? Why not
just one protocol handler function which checks the command at the top and
calls invoke_transport there?

Also, unless ATACB is a new standard (and I don't think it is, as the
Cypress datasheet uses the term 'vendor specific'), then your functions
need renaming. Instead of 'emulate_pass_thru_with_atacb', how about
something like 'cypress_atacb' -- since it's already a protocol handler,
everyone already knows it's for passing commands.

Matt

On Sat, Mar 08, 2008 at 06:32:05PM +0100, matthieu castet wrote:
> 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@xxxxxxx>
>
> 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),
> --
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--
Matthew Dharm Home: mdharm-usb@xxxxxxxxxxxxxxxxxx
Maintainer, Linux USB Mass Storage Driver

A: The most ironic oxymoron wins ...
DP: "Microsoft Works"
A: Uh, okay, you win.
-- A.J. & Dust Puppy
User Friendly, 1/18/1998

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