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

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

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Matthew Dharm wrote:
> On Sun, Mar 09, 2008 at 10:42:50PM +0100, matthieu castet wrote:
>> Hi
>>
>> here an update version of the patch
> 
> We're getting very close here.
> 
>> + 	/* this value can change, but most(all ?) manufacturers keep the 
>> cypress
>> +	 * default : 0x24
>> +	 */
> 
> Line wrap problem.  This happens a few times in your patch, but this was
> the first one I noticed.
Ha, may be my mailer is broken with inline patch. I will attach the next 
one.

> 
>> +	srb->cmnd[0] = 0x24;
>> +	srb->cmnd[1] = 0x24;
>> +	srb->cmnd[2] = 0;
>> +
>> +	srb->cmnd[3] = 0xff - 1;
>> +	srb->cmnd[4] = 1;
> 
> What are these magic constants?  Symbolic names or comments would be
> apropriate here.
Ok I will change that
> 
>> +	if (srb->cmnd[12] == ATA_CMD_ID_ATA || srb->cmnd[12] == 
>> ATA_CMD_ID_ATAPI)
>> +		srb->cmnd[2] |= (1<<7);
> 
> What does this block do?  In general, you could use some more comments
> about the code flow...
It's a bit that should be set for these commands. I will add a comment
about that.
> 
>> +	/* 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->subclass = US_SC_SCSI;
>> +		us->proto_handler = usb_stor_transparent_scsi_command;
>> +		goto end;
>> +	}
> 
> This is an interesting section of code.  Do you have reason to believe that
> some of the units you've claimed via unusual_devs.h do not support this
> protocol, or are you just being forward-looking?
when I did this code, I was wondering where to plug the hook and was 
thinking about auto-discovering of atacb device.
I think I can remove it now and replace it with a message.
But I should find a way to discover other devices supporting atacb. May 
be I will do a userspace tool for that.

> 
> Either way, some debug printout would be good here...
> 
>> --- linux-2.6.24.2.orig/include/linux/usb_usual.h	2008-03-09 
>> 21:15:01.000000000 +0100
>> +++ linux-2.6.24.2/include/linux/usb_usual.h	2008-03-09 
>> 21:24:12.000000000 +0100
>> @@ -81,8 +81,9 @@
>>  #define US_SC_8070	0x05		/* Removable media */
>>  #define US_SC_SCSI	0x06		/* Transparent */
>>  #define US_SC_ISD200    0x07		/* ISD200 ATA */
>> +#define US_SC_CYP_ATACB 0x08		/* Cypress ATACB */
>>  #define US_SC_MIN	US_SC_RBC
>> -#define US_SC_MAX	US_SC_ISD200
>> +#define US_SC_MAX	US_SC_CYP_ATACB
>>
>>  #define US_SC_DEVICE	0xff		/* Use device's value */
> 
> I thought we changed this so that the non-spec protocols started from 0xfe
> and worked their way down?
Oh, I suppose I need to port this to lastest git.

- I updated the patch to git version (I have to change some stuff for 
scsi) and I follow the above comments.


Matthieu

PS : I don't have a running kernel git version. So I only build the mass 
storage driver with this patch, I didn't run it.
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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/drivers/usb/storage/unusual_devs.h
===================================================================
--- linux-2.6.orig/drivers/usb/storage/unusual_devs.h	2008-02-28 11:21:20.000000000 +0100
+++ linux-2.6/drivers/usb/storage/unusual_devs.h	2008-03-13 21:19:21.000000000 +0100
@@ -1620,6 +1620,14 @@
 		US_SC_DEVICE, US_PR_DEVICE, NULL,
 		US_FL_CAPACITY_HEURISTICS),
 
+#ifdef CONFIG_USB_STORAGE_CYPRESS_ATACB
+UNUSUAL_DEV(  0x04b4, 0x6830, 0x0000, 0x9999,
+		"Cypress",
+		"Cypress AT2LP",
+		US_SC_CYP_ATACB, US_PR_BULK, NULL,
+		0),
+#endif
+
 /* 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),
Index: linux-2.6/drivers/usb/storage/cypress_atacb.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/drivers/usb/storage/cypress_atacb.c	2008-03-13 21:29:26.000000000 +0100
@@ -0,0 +1,203 @@
+/*
+ * 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 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;
+
+		/* 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);
+
+		/* 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];  /* 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;
+}
Index: linux-2.6/drivers/usb/storage/cypress_atacb.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/drivers/usb/storage/cypress_atacb.h	2008-03-13 21:19:21.000000000 +0100
@@ -0,0 +1,25 @@
+/*
+ * 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.
+ */
+
+#ifndef _CYPRESS_ATACB_H_
+#define _CYPRESS_ATACB_H_
+extern void cypress_atacb_passthrough(struct scsi_cmnd*, struct us_data*);
+#endif
Index: linux-2.6/drivers/usb/storage/Kconfig
===================================================================
--- linux-2.6.orig/drivers/usb/storage/Kconfig	2007-11-29 11:03:48.000000000 +0100
+++ linux-2.6/drivers/usb/storage/Kconfig	2008-03-13 21:19:21.000000000 +0100
@@ -145,6 +145,17 @@
 	  on the resulting scsi device node returns the Karma to normal
 	  operation.
 
+config USB_STORAGE_CYPRESS_ATACB
+	bool "SAT emulation on Cypress USB/ATA Bridge with ATACB"
+	depends on USB_STORAGE
+	---help---
+	  Say Y here if you want to use SAT (ata pass through) on devices based
+	  on the Cypress USB/ATA bridge supporting ATACB. This will allow you
+	  to use tools to tune and monitor your drive (like hdparm or smartctl).
+
+	  If you say no here your device will still work with the standard usb
+	  mass storage class.
+
 config USB_LIBUSUAL
 	bool "The shared table of common (or usual) storage devices"
 	depends on USB
Index: linux-2.6/drivers/usb/storage/Makefile
===================================================================
--- linux-2.6.orig/drivers/usb/storage/Makefile	2007-06-08 14:22:39.000000000 +0200
+++ linux-2.6/drivers/usb/storage/Makefile	2008-03-13 21:19:21.000000000 +0100
@@ -21,6 +21,7 @@
 usb-storage-obj-$(CONFIG_USB_STORAGE_ALAUDA)	+= alauda.o
 usb-storage-obj-$(CONFIG_USB_STORAGE_ONETOUCH)	+= onetouch.o
 usb-storage-obj-$(CONFIG_USB_STORAGE_KARMA)	+= karma.o
+usb-storage-obj-$(CONFIG_USB_STORAGE_CYPRESS_ATACB) += cypress_atacb.o
 
 usb-storage-objs :=	scsiglue.o protocol.o transport.o usb.o \
 			initializers.o $(usb-storage-obj-y)
Index: linux-2.6/drivers/usb/storage/scsiglue.c
===================================================================
--- linux-2.6.orig/drivers/usb/storage/scsiglue.c	2008-02-05 09:42:21.000000000 +0100
+++ linux-2.6/drivers/usb/storage/scsiglue.c	2008-03-13 21:19:21.000000000 +0100
@@ -132,7 +132,7 @@
 		/* Disk-type devices use MODE SENSE(6) if the protocol
 		 * (SubClass) is Transparent SCSI, otherwise they use
 		 * MODE SENSE(10). */
-		if (us->subclass != US_SC_SCSI)
+		if (us->subclass != US_SC_SCSI && us->subclass != US_SC_CYP_ATACB)
 			sdev->use_10_for_ms = 1;
 
 		/* Many disks only accept MODE SENSE transfer lengths of
Index: linux-2.6/drivers/usb/storage/transport.c
===================================================================
--- linux-2.6.orig/drivers/usb/storage/transport.c	2008-02-28 11:21:20.000000000 +0100
+++ linux-2.6/drivers/usb/storage/transport.c	2008-03-13 21:19:21.000000000 +0100
@@ -603,7 +603,8 @@
 		scsi_eh_prep_cmnd(srb, &ses, NULL, 0, US_SENSE_SIZE);
 
 		/* FIXME: we must do the protocol translation here */
-		if (us->subclass == US_SC_RBC || us->subclass == US_SC_SCSI)
+		if (us->subclass == US_SC_RBC || us->subclass == US_SC_SCSI ||
+				us->subclass == US_SC_CYP_ATACB)
 			srb->cmd_len = 6;
 		else
 			srb->cmd_len = 12;
Index: linux-2.6/drivers/usb/storage/usb.c
===================================================================
--- linux-2.6.orig/drivers/usb/storage/usb.c	2007-11-29 11:03:48.000000000 +0100
+++ linux-2.6/drivers/usb/storage/usb.c	2008-03-13 21:19:21.000000000 +0100
@@ -101,6 +101,9 @@
 #ifdef CONFIG_USB_STORAGE_KARMA
 #include "karma.h"
 #endif
+#ifdef CONFIG_USB_STORAGE_CYPRESS_ATACB
+#include "cypress_atacb.h"
+#endif
 
 /* Some informational data */
 MODULE_AUTHOR("Matthew Dharm <mdharm-usb@one-eyed-alien.net>");
@@ -708,6 +711,13 @@
 		break;
 #endif
 
+#ifdef CONFIG_USB_STORAGE_CYPRESS_ATACB
+	case US_SC_CYP_ATACB:
+		us->protocol_name = "Transparent SCSI with Cypress ATACB";
+		us->proto_handler = cypress_atacb_passthrough;
+		break;
+#endif
+
 	default:
 		return -EIO;
 	}
Index: linux-2.6/include/linux/usb_usual.h
===================================================================
--- linux-2.6.orig/include/linux/usb_usual.h	2008-02-05 09:42:23.000000000 +0100
+++ linux-2.6/include/linux/usb_usual.h	2008-03-13 21:20:33.000000000 +0100
@@ -83,6 +83,7 @@
 #define US_SC_LOCKABLE	0x07		/* Password-protected */
 
 #define US_SC_ISD200    0xf0		/* ISD200 ATA */
+#define US_SC_CYP_ATACB 0xf1		/* Cypress ATACB */
 #define US_SC_DEVICE	0xff		/* Use device's value */
 
 /* Protocols */