scsi: ppa: Add a module parameter for the transfer mode

I have an Iomega Z100P2 zip drive, but it does not work with my StarTech
PEX1P2 AX99100 PCIe parallel port, which evidently does not support 16-bit
or 32-bit EPP. Currently the only way to tell the PPA driver to use 8-bit
EPP is to write 'mode=3' to /proc/scsi/ppa/*, but the driver doesn't
actually distinguish between the three EPP modes and still tries to use
16-bit or 32-bit EPP. And even if writing to that file did make the driver
use 8-bit EPP, it still wouldn't do me any good because by the time that
file exists, the drive has already failed to initialize.

Add a new parameter /sys/module/ppa/mode to set the transfer mode before
initializing the drive. This parameter replaces the use of
CONFIG_SCSI_IZIP_EPP16 in the PPA driver.

At the same time, default to 8-bit EPP. 16-bit and 32-bit EPP are not
necessary for the drive to function, nor are they part of the IEEE 1284
standard, so the driver should not assume that they are available.

Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
Link: https://lore.kernel.org/r/20230807155856.362864-2-alexhenrie24@gmail.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/Kconfig b/drivers/scsi/Kconfig
index 4962ce9..695a57d 100644 (file)
--- a/drivers/scsi/Kconfig
+++ b/drivers/scsi/Kconfig
@@ -836,7 +836,7 @@ config SCSI_IMM
 
 config SCSI_IZIP_EPP16
        bool "ppa/imm option - Use slow (but safe) EPP-16"
-       depends on SCSI_PPA || SCSI_IMM
+       depends on SCSI_IMM
        help
          EPP (Enhanced Parallel Port) is a standard for parallel ports which
          allows them to act as expansion buses that can handle up to 64

diff --git a/drivers/scsi/ppa.c b/drivers/scsi/ppa.c
index d1f6aa2..19f0b93 100644 (file)
--- a/drivers/scsi/ppa.c
+++ b/drivers/scsi/ppa.c
@@ -45,6 +45,11 @@ typedef struct {
 
 #include  "ppa.h"
 
+static unsigned int mode = PPA_AUTODETECT;
+module_param(mode, uint, 0644);
+MODULE_PARM_DESC(mode, "Transfer mode (0 = Autodetect, 1 = SPP 4-bit, "
+       "2 = SPP 8-bit, 3 = EPP 8-bit, 4 = EPP 16-bit, 5 = EPP 32-bit");
+
 static struct scsi_pointer *ppa_scsi_pointer(struct scsi_cmnd *cmd)
 {
        return scsi_cmd_priv(cmd);
@@ -157,7 +162,7 @@ static int ppa_show_info(struct seq_file *m, struct Scsi_Host *host)
        return 0;
 }
 
-static int device_check(ppa_struct *dev);
+static int device_check(ppa_struct *dev, bool autodetect);
 
 #if PPA_DEBUG > 0
 #define ppa_fail(x,y) printk("ppa: ppa_fail(%i) from %s at line %d\n",\
@@ -302,13 +307,10 @@ static int ppa_out(ppa_struct *dev, char *buffer, int len)
        case PPA_EPP_8:
                epp_reset(ppb);
                w_ctr(ppb, 0x4);
-#ifdef CONFIG_SCSI_IZIP_EPP16
-               if (!(((long) buffer | len) & 0x01))
-                       outsw(ppb + 4, buffer, len >> 1);
-#else
-               if (!(((long) buffer | len) & 0x03))
+               if (dev->mode == PPA_EPP_32 && !(((long) buffer | len) & 0x01))
                        outsl(ppb + 4, buffer, len >> 2);
-#endif
+               else if (dev->mode == PPA_EPP_16 && !(((long) buffer | len) & 0x03))
+                       outsw(ppb + 4, buffer, len >> 1);
                else
                        outsb(ppb + 4, buffer, len);
                w_ctr(ppb, 0xc);
@@ -355,13 +357,10 @@ static int ppa_in(ppa_struct *dev, char *buffer, int len)
        case PPA_EPP_8:
                epp_reset(ppb);
                w_ctr(ppb, 0x24);
-#ifdef CONFIG_SCSI_IZIP_EPP16
-               if (!(((long) buffer | len) & 0x01))
-                       insw(ppb + 4, buffer, len >> 1);
-#else
-               if (!(((long) buffer | len) & 0x03))
+               if (dev->mode == PPA_EPP_32 && !(((long) buffer | len) & 0x03))
                        insl(ppb + 4, buffer, len >> 2);
-#endif
+               else if (dev->mode == PPA_EPP_16 && !(((long) buffer | len) & 0x01))
+                       insw(ppb + 4, buffer, len >> 1);
                else
                        insb(ppb + 4, buffer, len);
                w_ctr(ppb, 0x2c);
@@ -469,6 +468,27 @@ static int ppa_init(ppa_struct *dev)
 {
        int retv;
        unsigned short ppb = dev->base;
+       bool autodetect = dev->mode == PPA_AUTODETECT;
+
+       if (autodetect) {
+               int modes = dev->dev->port->modes;
+               int ppb_hi = dev->dev->port->base_hi;
+
+               /* Mode detection works up the chain of speed
+                * This avoids a nasty if-then-else-if-... tree
+                */
+               dev->mode = PPA_NIBBLE;
+
+               if (modes & PARPORT_MODE_TRISTATE)
+                       dev->mode = PPA_PS2;
+
+               if (modes & PARPORT_MODE_ECP) {
+                       w_ecr(ppb_hi, 0x20);
+                       dev->mode = PPA_PS2;
+               }
+               if ((modes & PARPORT_MODE_EPP) && (modes & PARPORT_MODE_ECP))
+                       w_ecr(ppb_hi, 0x80);
+       }
 
        ppa_disconnect(dev);
        ppa_connect(dev, CONNECT_NORMAL);
@@ -492,7 +512,7 @@ static int ppa_init(ppa_struct *dev)
        if (retv)
                return -EIO;
 
-       return device_check(dev);
+       return device_check(dev, autodetect);
 }
 
 static inline int ppa_send_command(struct scsi_cmnd *cmd)
@@ -883,7 +903,7 @@ static int ppa_reset(struct scsi_cmnd *cmd)
        return SUCCESS;
 }
 
-static int device_check(ppa_struct *dev)
+static int device_check(ppa_struct *dev, bool autodetect)
 {
        /* This routine looks for a device and then attempts to use EPP
           to send a command. If all goes as planned then EPP is available. */
@@ -895,8 +915,8 @@ static int device_check(ppa_struct *dev)
        old_mode = dev->mode;
        for (loop = 0; loop < 8; loop++) {
                /* Attempt to use EPP for Test Unit Ready */
-               if ((ppb & 0x0007) == 0x0000)
-                       dev->mode = PPA_EPP_32;
+               if (autodetect && (ppb & 0x0007) == 0x0000)
+                       dev->mode = PPA_EPP_8;
 
 second_pass:
                ppa_connect(dev, CONNECT_EPP_MAYBE);
@@ -924,7 +944,7 @@ second_pass:
                        udelay(1000);
                        ppa_disconnect(dev);
                        udelay(1000);
-                       if (dev->mode == PPA_EPP_32) {
+                       if (dev->mode != old_mode) {
                                dev->mode = old_mode;
                                goto second_pass;
                        }
@@ -947,7 +967,7 @@ second_pass:
                        udelay(1000);
                        ppa_disconnect(dev);
                        udelay(1000);
-                       if (dev->mode == PPA_EPP_32) {
+                       if (dev->mode != old_mode) {
                                dev->mode = old_mode;
                                goto second_pass;
                        }
@@ -1026,7 +1046,6 @@ static int __ppa_attach(struct parport *pb)
        DEFINE_WAIT(wait);
        ppa_struct *dev, *temp;
        int ports;
-       int modes, ppb, ppb_hi;
        int err = -ENOMEM;
        struct pardev_cb ppa_cb;
 
@@ -1034,7 +1053,7 @@ static int __ppa_attach(struct parport *pb)
        if (!dev)
                return -ENOMEM;
        dev->base = -1;
-       dev->mode = PPA_AUTODETECT;
+       dev->mode = mode < PPA_UNKNOWN ? mode : PPA_AUTODETECT;
        dev->recon_tmo = PPA_RECON_TMO;
        init_waitqueue_head(&waiting);
        temp = find_parent();
@@ -1069,25 +1088,8 @@ static int __ppa_attach(struct parport *pb)
        }
        dev->waiting = NULL;
        finish_wait(&waiting, &wait);
-       ppb = dev->base = dev->dev->port->base;
-       ppb_hi = dev->dev->port->base_hi;
-       w_ctr(ppb, 0x0c);
-       modes = dev->dev->port->modes;
-
-       /* Mode detection works up the chain of speed
-        * This avoids a nasty if-then-else-if-... tree
-        */
-       dev->mode = PPA_NIBBLE;
-
-       if (modes & PARPORT_MODE_TRISTATE)
-               dev->mode = PPA_PS2;
-
-       if (modes & PARPORT_MODE_ECP) {
-               w_ecr(ppb_hi, 0x20);
-               dev->mode = PPA_PS2;
-       }
-       if ((modes & PARPORT_MODE_EPP) && (modes & PARPORT_MODE_ECP))
-               w_ecr(ppb_hi, 0x80);
+       dev->base = dev->dev->port->base;
+       w_ctr(dev->base, 0x0c);
 
        /* Done configuration */
 

diff --git a/drivers/scsi/ppa.h b/drivers/scsi/ppa.h
index 6a1f8a2..098bcf7 100644 (file)
--- a/drivers/scsi/ppa.h
+++ b/drivers/scsi/ppa.h
@@ -107,11 +107,7 @@ static char *PPA_MODE_STRING[] =
     "PS/2",
     "EPP 8 bit",
     "EPP 16 bit",
-#ifdef CONFIG_SCSI_IZIP_EPP16
-    "EPP 16 bit",
-#else
     "EPP 32 bit",
-#endif
     "Unknown"};
 
 /* other options */