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Cleanup DF driver cache code
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@ghaerr
ghaerr committed Oct 17, 2024
1 parent 2f4d53d commit 8376ef7
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Showing 4 changed files with 117 additions and 135 deletions.
154 changes: 68 additions & 86 deletions elks/arch/i86/drivers/block/directfd.c
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Original file line number Diff line number Diff line change
Expand Up @@ -171,14 +171,6 @@ static unsigned char running; /* keep track of motors already running */
*/
#define MAX_BUFFER_SECTORS 18

/*
* The 8237 DMA controller cannot access data above 1MB on the origianl PC
* (4 bit page register). The AT is different, the page reg is 8 bits while the
* 2nd DMA controller transfers words only, not bytes and thus up to 128k bytes
* in one 'swoop'.
*/
#define LAST_DMA_ADDR (0x100000L - BLOCK_SIZE) /* enforce the 1M limit */

#define LINADDR(seg, offs) ((unsigned long)((((unsigned long)(seg)) << 4) + (unsigned)(offs)))

/*
Expand Down Expand Up @@ -285,7 +277,7 @@ static unsigned int changed_floppies;
#define MIN_ERRORS 0

/*
* The block buffer is used for all writes, for formatting and for reads
* The block buffer is used for all writes and for reads
* in case track buffering doesn't work or has been turned off.
*/
static char *floppy_buffer;
Expand All @@ -297,14 +289,15 @@ static char *floppy_buffer;
*/
#define NO_TRACK 255

static int read_track; /* set to read entire track */
static int buffer_track = -1;
static int buffer_drive = -1;
static bool use_cache; /* read entire track when set*/
static int use_bounce; /* XMS or 64k address wrap when set */
static unsigned char cache_drive = 255;
static int cache_track;
static int cur_spec1 = -1;
static int cur_rate = -1;
static struct floppy_struct *floppy;
static unsigned char current_drive = 255;
static unsigned char sector;
static unsigned char sector; /* zero relative sector number for I/O start */
static unsigned char head;
static unsigned char track;
static unsigned char seek_track;
Expand All @@ -327,6 +320,12 @@ static void DFPROC delay_loop(int cnt)
while (cnt-- > 0) asm("nop");
}

static void invalidate_cache(void)
{
if (cache_drive != 255) debug_cache("INV%d ", cache_drive);
cache_drive = 255;
}

static void select_callback(int unused)
{
DEBUG("SC;");
Expand Down Expand Up @@ -461,6 +460,11 @@ void request_done(int uptodate)
* opcode. This routine sets up the DMA chip. Note that the chip is not
* capable of doing a DMA across a 64K boundary (e.g., you can't read a
* 512-byte block starting at physical address 65520).
*
* The 8237 DMA controller cannot access data above 1MB on the original PC
* (4 bit page register). The AT is different, the page reg is 8 bits while the
* 2nd DMA controller transfers words only, not bytes and thus up to 128k bytes
* in one 'swoop'.
*/
#define DMA_INIT DMA1_MASK_REG
#define DMA_FLIPFLOP DMA1_CLEAR_FF_REG
Expand All @@ -474,32 +478,23 @@ static void DFPROC setup_DMA(void)
struct request *req = CURRENT;
unsigned int count, physaddr;
unsigned long dma_addr;
int use_xms;

DEBUG("setupDMA ");
#pragma GCC diagnostic ignored "-Wshift-count-overflow"
use_xms = req->rq_seg >> 16; /* will be nonzero only if XMS configured & XMS buffer */
physaddr = (req->rq_seg << 4) + (unsigned int)req->rq_buffer;

count = req->rq_nr_sectors << 9;
if (use_xms || (physaddr + count) < physaddr)
dma_addr = LAST_DMA_ADDR + 1; /* force use of bounce buffer */
physaddr = (req->rq_seg << 4) + (unsigned int)req->rq_buffer;
use_bounce = (req->rq_seg >> 16) || (physaddr + count) < physaddr;
if (use_bounce)
dma_addr = LINADDR(kernel_ds, floppy_buffer);
else
dma_addr = LINADDR(req->rq_seg, req->rq_buffer);

DEBUG("setupDMA ");

if (read_track) { /* mark buffer-track bad, in case all this fails.. */
buffer_drive = buffer_track = -1;
count = floppy->sect << 9; /* sects/trk (one side) times 512 */
if (floppy->sect & 1 && !head)
count += 512; /* handle split block */
if (use_cache) {
dma_addr = LINADDR(DMASEG, 0);
} else if (dma_addr >= LAST_DMA_ADDR) {
dma_addr = LINADDR(kernel_ds, floppy_buffer); /* use bounce buffer */
if (command == FD_WRITE) {
xms_fmemcpyw(floppy_buffer, kernel_ds, req->rq_buffer,
req->rq_seg, BLOCK_SIZE/2);
}
/* read sectors/track (one side) + split block */
count = (floppy->sect + (floppy->sect & 1 && !head)) << 9;
} else if (use_bounce && command == FD_WRITE) {
xms_fmemcpyw(floppy_buffer, kernel_ds, req->rq_buffer, req->rq_seg, BLOCK_SIZE/2);
}
DEBUG("%d/%lx;", count, dma_addr);

Expand Down Expand Up @@ -566,6 +561,7 @@ static void DFPROC bad_flp_intr(void)

DEBUG("bad_flpI-");
current_track = NO_TRACK;
invalidate_cache();
if (!CURRENT) return;
if (probing) {
probing++;
Expand All @@ -588,7 +584,6 @@ static void DFPROC bad_flp_intr(void)

/* Set perpendicular mode as required, based on data rate, if supported.
* 1Mbps data rate only possible with 82077-1.
* TODO: increase MAX_BUFFER_SECTORS.
*/
static void DFPROC perpendicular_mode(unsigned char rate)
{
Expand Down Expand Up @@ -662,11 +657,10 @@ static void DFPROC tell_sector(int nr)
static void rw_interrupt(void)
{
struct request *req = CURRENT;
unsigned char *buffer_area;
int nr, bad;

nr = result();
/* NOTE: If read_track is active and sector count is uneven, ST0 will
/* NOTE: If use_cache is active and sector count is uneven, ST0 will
* always show HD1 as selected at this point. */
DEBUG("rwI%x|%x|%x-", ST0,ST1,ST2);

Expand Down Expand Up @@ -727,29 +721,20 @@ static void rw_interrupt(void)
if (probing) {
open_inode->i_size = (sector_t)floppy->size << 9;
nr = DEVICE_NR(req->rq_dev);
printk("df%d: Auto-detected floppy type %s\n", nr, floppy->name);
printk("df%d: auto-detected floppy type %s\n", nr, floppy->name);
current_type[nr] = floppy;
probing = 0;
}
if (read_track) {
if (use_cache) {
/* This encoding is ugly, should use block-start, block-end instead */
buffer_track = (seek_track << 1) + head;
buffer_drive = current_drive;
buffer_area = (unsigned char *)(sector << 9);
DEBUG("rd:%04x:%08lx->%04x:%04x;", DMASEG, buffer_area,
cache_drive = current_drive;
cache_track = (seek_track << 1) + head;
DEBUG("rd %04x:%04x->%08lx:%04x;", DMASEG, sector << 9,
(unsigned long)req->rq_seg, req->rq_buffer);
xms_fmemcpyw(req->rq_buffer, req->rq_seg, buffer_area, DMASEG, BLOCK_SIZE/2);
} else if (command == FD_READ
#ifndef CONFIG_FS_XMS_BUFFER
&& LINADDR(req->rq_seg, req->rq_buffer) >= LAST_DMA_ADDR
#endif
) {
/* if the dest buffer is out of reach for DMA (always the case if using
* XMS buffers) we need to read/write via the bounce buffer */
xms_fmemcpyw(req->rq_buffer, req->rq_seg, floppy_buffer,
kernel_ds, BLOCK_SIZE/2);
printk("df: illegal buffer usage, rq_buffer %04x:%04x\n",
req->rq_seg, req->rq_buffer);
xms_fmemcpyw(req->rq_buffer, req->rq_seg, (char *)(sector << 9), DMASEG,
BLOCK_SIZE/2);
} else if (use_bounce && command == FD_READ) {
xms_fmemcpyw(req->rq_buffer, req->rq_seg, floppy_buffer, kernel_ds, BLOCK_SIZE/2);
}
request_done(1);
DEBUG("RQOK;");
Expand All @@ -774,8 +759,8 @@ static void DFPROC setup_rw_floppy(void)
{
DEBUG("setup_rw-");
#if IODELAY || DEBUG_CACHE
int num_sectors = read_track
? floppy->sect + (floppy->sect & 1 && !head) - sector
int num_sectors = use_cache
? floppy->sect + (floppy->sect & 1 && !head) /* - sector */
: CURRENT->rq_nr_sectors;
#if IODELAY
static unsigned lasttrack;
Expand All @@ -789,19 +774,17 @@ static void DFPROC setup_rw_floppy(void)
while (!time_after(jiffies, timeout)) continue;
#endif
debug_cache("%s%d %lu(CHS %u,%u,%u-%u)\n",
read_track? "TR": (command == FD_WRITE? "WR": "RD"),
current_drive, CURRENT->rq_sector>>1, track, head, sector+1, sector+num_sectors);
use_cache? "TR": (command == FD_WRITE? "WR": "RD"),
current_drive, CURRENT->rq_sector>>1, track, head, /*sector + */ 1,
/*sector + */ num_sectors);
#endif
do_floppy = rw_interrupt;
setup_DMA();
output_byte(command);
output_byte(head << 2 | current_drive);
output_byte(track);
output_byte(head);
if (read_track)
output_byte(1); /* always start at 1 */
else
output_byte(sector+1);
output_byte(use_cache? 1: sector+1); /* start at sector 1 when caching */
output_byte(2); /* sector size = 512 */
output_byte(floppy->sect);
output_byte(floppy->gap);
Expand Down Expand Up @@ -838,14 +821,9 @@ static void seek_interrupt(void)
*/
static void DFPROC transfer(void)
{
#ifdef CONFIG_TRACK_CACHE
read_track = (command == FD_READ) && (CURRENT->rq_errors < 4) &&
(floppy->sect <= MAX_BUFFER_SECTORS);
#endif
DEBUG("trns%d-", read_track);

configure_fdc_mode(); /* ensure controller is in the right mode per transaction */
if (reset) { /* if output_byte timed out */
DEBUG("trns%d-", use_cache);
configure_fdc_mode(); /* ensure controller is in the right mode per transaction */
if (reset) { /* if output_byte timed out */
redo_fd_request();
return;
}
Expand Down Expand Up @@ -1120,8 +1098,8 @@ static void DFPROC floppy_ready(void)
current_type[current_drive] = NULL; /* comment out to keep last media format */
}

if (current_drive == buffer_drive)
buffer_track = -1;
if (current_drive == cache_drive)
invalidate_cache();

#if CHECK_DIR_REG
if (!reset && !recalibrate) {
Expand Down Expand Up @@ -1155,6 +1133,7 @@ static void DFPROC redo_fd_request(void)
struct request *req;
int type, drive;
unsigned int start, tmp;
char *cache_offset;

repeat:
req = CURRENT;
Expand Down Expand Up @@ -1212,34 +1191,37 @@ static void DFPROC redo_fd_request(void)
track = tmp / floppy->head;
seek_track = track << floppy->stretch;
command = (req->rq_cmd == READ)? FD_READ: FD_WRITE;
#ifdef CONFIG_TRACK_CACHE
use_cache = (command == FD_READ) && (req->rq_errors < 4) &&
(floppy->sect <= MAX_BUFFER_SECTORS);
#endif
DEBUG("df%d: %s sector %d CHS %d/%d/%d max %d stretch %d seek %d\n",
DEVICE_NR(req->rq_dev), req->rq_cmd==READ? "read": "write",
start, track, head, sector+1, floppy->sect, floppy->stretch, seek_track);

/* restart timer for hung operations, 6 secs probably too long ... */
del_timer(&fd_timeout);
fd_timeout.tl_expires = jiffies + TIMEOUT_CMD_COMPL;
add_timer(&fd_timeout);
DEBUG("prep %d|%d,%d|%d-", cache_track, seek_track, cache_drive, current_drive);

DEBUG("prep %d|%d,%d|%d-", buffer_track, seek_track, buffer_drive, current_drive);

if ((((seek_track << 1) + head) == buffer_track) && (current_drive == buffer_drive)) {
if (cache_drive == current_drive && cache_track == ((seek_track << 1) + head)) {
/* Requested block is in the buffer. If reading, go get it.
* If the sector count is odd, we buffer sectors+1 when head=0 to get an even
* number of sectors (full blocks). When head=1 we read the entire track
* and ignore the first sector.
* number of sectors (full blocks). When head=1 we read the entire track.
*/
DEBUG("cache CHS %d/%d/%d\n", seek_track, head, sector);
debug_cache2("CH %d ", start >> 1);
char *buf_ptr = (char *) (sector << 9);
if (command == FD_READ) { /* requested data is in buffer */
xms_fmemcpyw(req->rq_buffer, req->rq_seg, buf_ptr, DMASEG, BLOCK_SIZE/2);
cache_offset = (char *)(sector << 9);
if (command == FD_READ) { /* cache hit, no I/O necessary */
xms_fmemcpyw(req->rq_buffer, req->rq_seg, cache_offset, DMASEG, BLOCK_SIZE/2);
request_done(1);
goto repeat;
} else if (command == FD_WRITE) /* update track buffer */
xms_fmemcpyw(buf_ptr, DMASEG, req->rq_buffer, req->rq_seg, BLOCK_SIZE/2);
} else if (command == FD_WRITE) /* update track buffer, then write */
xms_fmemcpyw(cache_offset, DMASEG, req->rq_buffer, req->rq_seg, BLOCK_SIZE/2);
}

/* restart timer for hung operations, 6 secs probably too long ... */
del_timer(&fd_timeout);
fd_timeout.tl_expires = jiffies + TIMEOUT_CMD_COMPL;
add_timer(&fd_timeout);

if (seek_track != current_track)
seek = 1;

Expand Down Expand Up @@ -1347,7 +1329,7 @@ static int floppy_open(struct inode *inode, struct file *filp)
if (access_count == 0) {
err = floppy_register();
if (err) return err;
buffer_drive = buffer_track = -1;
invalidate_cache();
}

access_count++;
Expand Down
2 changes: 1 addition & 1 deletion elks/include/linuxmt/debug.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@
#define DEBUG_LEVEL 0 /* default startup debug level*/
#define DEBUG_BIOS 0 /* BIOS driver*/
#define DEBUG_BLK 0 /* block i/o*/
#define DEBUG_CACHE 0 /* floppy track cache*/
#define DEBUG_CACHE 1 /* floppy track cache*/
#define DEBUG_ETH 0 /* ethernet*/
#define DEBUG_FAT 0 /* FAT filesystem*/
#define DEBUG_FILE 0 /* sys open and file i/o*/
Expand Down
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