[bioshd] Implement park for ancient MFM/RLL disks

Really old drives, such as the two ST-412s in my IBM 5161, required
manual parking to ensure the r/w heads are over a safe location when the
disk spins down and the heads (intentionally!) crash onto the disk
surface.

In DOS land, this vital task was left up to the user, in the form of a
PARK command to be run before shutting down. In ELKS however, the kernel
should manage this automatically. An INT 13/AH=0Ch is invoked to seek
the disk to the last track when unmounted, and to all drives right
before halting the system.

elks/arch/i86/drivers/block/bios.c

@@ -222,6 +222,24 @@ int INITPROC bios_gethdinfo(struct drive_infot *drivep) {
     }
     return ndrives;
 }
+
+static void BFPROC bios_disk_park(struct drive_infot *drive)
+{
+    /* int 13 AH=0xC supports only 10 bits for cyl */
+    if (drive->cylinders > 1024 || drive->fdtype != -1) return;
+    BD_AX = 0x0C << 8;
+    BD_CX = ((drive->cylinders & 0xFF) << 8) | ((drive->cylinders & 0x300) >> 2) | 0x1; /* 0x1 = sector */
+    BD_DX = bios_drive_map[drive - drive_info];
+    call_bios(&bdt);
+}
+
+void bios_disk_park_all(void)
+{
+    int i;
+    for (i = 0; i < NUM_DRIVES; ++i)
+        bios_disk_park(&drive_info[i]);
+}
+
 #endif
 
 #ifdef CONFIG_BLK_DEV_BFD_HARD

elks/arch/i86/drivers/block/bioshd.c

@@ -78,7 +78,7 @@ static int fd_count = 0;                /* number of floppy disks */
 static int hd_count = 0;                /* number of hard disks */
 
 static int access_count[NUM_DRIVES];    /* device open count */
-static struct drive_infot drive_info[NUM_DRIVES];   /* operating drive info */
+struct drive_infot drive_info[NUM_DRIVES];   /* operating drive info */
 static struct drive_infot *cache_drive;
 struct drive_infot *last_drive;         /* set to last drivep-> used in read/write */
 extern struct drive_infot fd_types[];   /* BIOS floppy formats */

elks/arch/i86/drivers/block/rd.c

@@ -40,7 +40,7 @@ static struct {			/* ramdrive information*/
     int start;			/* starting memory segment*/
     int valid;			/* ramdisk data valid flag*/
     rd_sector_t size;		/* ramdisk size in 512 byte sectors*/
-} drive_info[MAX_DRIVES] = {
+} rd_info[MAX_DRIVES] = {
 #if CONFIG_RAMDISK_SEGMENT
     {0, 1, CONFIG_RAMDISK_SECTORS}
 #endif
@@ -76,13 +76,13 @@ static int rd_open(struct inode *inode, struct file *filp)
     debug("RD: open /dev/rd%d\n", target);
     if (!rd_initialised || target >= MAX_DRIVES
 #if CONFIG_RAMDISK_SEGMENT
-        || !drive_info[target].valid
+        || !rd_info[target].valid
 #endif
                                                 )
         return -ENXIO;
 
     ++access_count[target];
-    inode->i_size = (long)drive_info[target].size << 9;
+    inode->i_size = (long)rd_info[target].size << 9;
     return 0;
 }
 
@@ -115,9 +115,9 @@ static int dealloc(int target)
 {
     int i, j;
 
-    i = drive_info[target].start;
+    i = rd_info[target].start;
     debug("RD: dealloc target %d, index %d, size %d sectors\n",
-	   target, i, drive_info[target].size);
+	   target, i, rd_info[target].size);
     while (i != -1 && rd_segment[i].sectors != 0) {
 	j = i;
 	debug("RD: dealloc purging rd_segment[%d].seg = 0x%x, next index %d, size = %d\n",
@@ -132,8 +132,8 @@ static int dealloc(int target)
 	debug("RD: dealloc status rd_segment[%d].seg = 0x%x, next index %d, size = %d\n",
 	     j, rd_segment[j].seg, rd_segment[j].next, rd_segment[j].sectors);
     }
-    drive_info[target].valid = 0;
-    drive_info[target].size = 0;
+    rd_info[target].valid = 0;
+    rd_info[target].size = 0;
     return 0;
 }
 
@@ -150,10 +150,10 @@ static int rd_ioctl(register struct inode *inode, struct file *file,
     debug("RD: ioctl %d %s\n", target, (cmd ? "kill" : "make"));
     switch (cmd) {
     case RDCREATE:
-	if (drive_info[target].valid)
+	if (rd_info[target].valid)
 	    return -EBUSY;
 
-	drive_info[target].size = 0;
+	rd_info[target].size = 0;
 	k = -1;
 	for (i = 0; i <= (arg - 1) / ((ALLOC_SIZE / 1024) * PARA); i++) {
 		j = find_free_seg();	/* find free place in queue */
@@ -163,7 +163,7 @@ static int rd_ioctl(register struct inode *inode, struct file *file,
 		    return -ENOMEM;
 		}
 		if (i == 0)
-		    drive_info[target].start = j;
+		    rd_info[target].start = j;
 
 		if (i == (arg / ((ALLOC_SIZE / 1024) * PARA)))
 		    /* size in 16 byte pages = (arg % 64) * 64 */
@@ -185,7 +185,7 @@ static int rd_ioctl(register struct inode *inode, struct file *file,
 		/* recalculate size to reflect size in sectors, not pages */
 		size = size / (RD_SECTOR_SIZE / PARA);
 		rd_segment[j].sectors = size;
-		drive_info[target].size += rd_segment[j].sectors;
+		rd_info[target].size += rd_segment[j].sectors;
 		size = (long) rd_segment[j].sectors * RD_SECTOR_SIZE;
 		debug("RD: index %d set to %d sectors, %ld bytes\n",
 		       j, rd_segment[j].sectors, size);
@@ -198,14 +198,14 @@ static int rd_ioctl(register struct inode *inode, struct file *file,
 		    rd_segment[k].next = j;	/* set link to next index */
 		k = j;
 	}
-	drive_info[target].valid = 1;
+	rd_info[target].valid = 1;
 	debug("RD: ramdisk %d created sectors %d index %d bytes %ld\n",
-		target, drive_info[target].size, drive_info[target].start,
-		(long)drive_info[target].size * RD_SECTOR_SIZE);
+		target, rd_info[target].size, rd_info[target].start,
+		(long)rd_info[target].size * RD_SECTOR_SIZE);
 	return 0;
 
     case RDDESTROY:
-	if (drive_info[target].valid) {
+	if (rd_info[target].valid) {
 	    invalidate_inodes(inode->i_rdev);
 	    invalidate_buffers(inode->i_rdev);
 	    dealloc(target);
@@ -241,18 +241,18 @@ static void do_rd_request(void)
 	target = DEVICE_NR(req->rq_dev);
 	debug("RD: %s dev %d sector %d, ", req->rq_cmd == READ? "read": "write",
 		target, start);
-	if (drive_info[target].valid == 0 ||
-                start + req->rq_nr_sectors > drive_info[target].size) {
+	if (rd_info[target].valid == 0 ||
+                start + req->rq_nr_sectors > rd_info[target].size) {
 	    debug("rd%d: sector %d beyond max %d\n",
-		 target, start, drive_info[target].size);
+		 target, start, rd_info[target].size);
 	    end_request(0);
 	    continue;
 	}
 
         for (count = 0; count < req->rq_nr_sectors; count++) {
             /* find appropriate memory segment and sector offset*/
             offset = start;
-            index = drive_info[target].start;
+            index = rd_info[target].start;
             debug("index %d, ", index);
             while (offset > rd_segment[index].sectors) {
                 offset -= rd_segment[index].sectors;
@@ -293,7 +293,7 @@ void INITPROC rd_init(void)
 
 #if CONFIG_RAMDISK_SEGMENT
 	printk("rd: %dK ramdisk at %x:0000\n",
-	    drive_info[0].size >> 1, rd_segment[0].seg);
+	    rd_info[0].size >> 1, rd_segment[0].seg);
 
 #if (CONFIG_RAMDISK_SECTORS > 128)
 	/* build segment array for preloaded ramdisks > 64k*/

elks/include/linuxmt/biosparm.h

@@ -87,5 +87,8 @@ void BFPROC bios_copy_ddpt(void);
 struct drive_infot;
 void BFPROC bios_switch_device98(int target, unsigned int device,
         struct drive_infot *drivep);
+#ifdef CONFIG_BLK_DEV_BHD
+void bios_disk_park_all(void);
+#endif
 
 #endif

elks/include/linuxmt/genhd.h

@@ -78,6 +78,7 @@ struct gendisk
 
 extern struct drive_infot *last_drive;  /* set to last drivep-> used in read/write */
 extern unsigned char bios_drive_map[];  /* map drive to BIOS drivenum */
+extern struct drive_infot drive_info[];
 
 extern struct gendisk *gendisk_head;    /* linked list of disks */
 

elks/kernel/sys.c

@@ -4,6 +4,7 @@
  *  Copyright (C) 1991, 1992  Linus Torvalds
  */
 
+#include <linuxmt/biosparm.h>
 #include <linuxmt/config.h>
 #include <linuxmt/errno.h>
 #include <linuxmt/sched.h>
@@ -48,16 +49,25 @@ int sys_reboot(unsigned int magic, unsigned int magic_too, int flag)
 		C_A_D = flag;
 		return 0;
 	    case 0x0123:		/* reboot*/
+#ifdef CONFIG_BLK_DEV_BHD
+		bios_disk_park_all();
+#endif
 		hard_reset_now();
 		printk("Reboot failed\n");
 		/* fall through*/
 	    case 0x6789:		/* shutdown*/
 		sys_kill(1, SIGKILL);
 		sys_kill(-1, SIGKILL);
+#ifdef CONFIG_BLK_DEV_BHD
+		bios_disk_park_all();
+#endif
 		printk("System halted\n");
 		do_exit(0);
 		/* no return*/
 	    case 0xDEAD:		/* poweroff*/
+#ifdef CONFIG_BLK_DEV_BHD
+		bios_disk_park_all();
+#endif
 		apm_shutdown_now();
 		printk("APM shutdown failed\n");
 	}