cm206.c

还有没有人研究过cdrom 的驱动源码啊

inline uch wait_dsb(void)
{
	return receive_byte(DSB_TIMEOUT);
}

int type_0_command(int command, int expect_dsb)
{
	int e;
	clear_ur();
	if (command != (e = send_receive(command))) {
		debug(("command 0x%x echoed as 0x%x\n", command, e));
		stats(echo);
		return -1;
	}
	if (expect_dsb) {
		cd->dsb = wait_dsb();	/* wait for command to finish */
	}
	return 0;
}

int type_1_command(int command, int bytes, uch * status)
{				/* returns info */
	int i;
	if (type_0_command(command, 0))
		return -1;
	for (i = 0; i < bytes; i++)
		status[i] = send_receive(c_gimme);
	return 0;
}

/* This function resets the adapter card. We'd better not do this too
 * often, because it tends to generate `lost interrupts.' */
void reset_cm260(void)
{
	outw(dc_normal | dc_initialize | READ_AHEAD, r_data_control);
	udelay(10);		/* 3.3 mu sec minimum */
	outw(dc_normal | READ_AHEAD, r_data_control);
}

/* fsm: frame-sec-min from linear address; one of many */
void fsm(int lba, uch * fsm)
{
	fsm[0] = lba % 75;
	lba /= 75;
	lba += 2;
	fsm[1] = lba % 60;
	fsm[2] = lba / 60;
}

inline int fsm2lba(uch * fsm)
{
	return fsm[0] + 75 * (fsm[1] - 2 + 60 * fsm[2]);
}

inline int f_s_m2lba(uch f, uch s, uch m)
{
	return f + 75 * (s - 2 + 60 * m);
}

int start_read(int start)
{
	uch read_sector[4] = { c_read_data, };
	int i, e;

	fsm(start, &read_sector[1]);
	clear_ur();
	for (i = 0; i < 4; i++)
		if (read_sector[i] != (e = send_receive(read_sector[i]))) {
			debug(("read_sector: %x echoes %x\n",
			       read_sector[i], e));
			stats(echo);
			if (e == 0xff) {	/* this seems to happen often */
				e = receive_echo();
				debug(("Second try %x\n", e));
				if (e != read_sector[i])
					return -1;
			}
		}
	return 0;
}

int stop_read(void)
{
	int e;
	type_0_command(c_stop, 0);
	if ((e = receive_echo()) != 0xff) {
		debug(("c_stop didn't send 0xff, but 0x%x\n", e));
		stats(stop_0xff);
		return -1;
	}
	return 0;
}

/* This function starts to read sectors in adapter memory, the
   interrupt routine should stop the read. In fact, the bottom_half
   routine takes care of this. Set a flag `background' in the cd
   struct to indicate the process. */

int read_background(int start, int reading)
{
	if (cd->background)
		return -1;	/* can't do twice */
	outw(dc_normal | BACK_AHEAD, r_data_control);
	if (!reading && start_read(start))
		return -2;
	cd->adapter_first = cd->adapter_last = start;
	cd->background = 1;	/* flag a read is going on */
	return 0;
}

#ifdef USE_INSW
#define transport_data insw
#else
/* this routine implements insw(,,). There was a time i had the
   impression that there would be any difference in error-behaviour. */
void transport_data(int port, ush * dest, int count)
{
	int i;
	ush *d;
	for (i = 0, d = dest; i < count; i++, d++)
		*d = inw(port);
}
#endif


#define MAX_TRIES 100
int read_sector(int start)
{
	int tries = 0;
	if (cd->background) {
		cd->background = 0;
		cd->adapter_last = -1;	/* invalidate adapter memory */
		stop_read();
	}
	cd->fifo_overflowed = 0;
	reset_cm260();		/* empty fifo etc. */
	if (start_read(start))
		return -1;
	do {
		if (sleep_or_timeout(&cd->data, DATA_TIMEOUT)) {
			debug(("Read timed out sector 0x%x\n", start));
			stats(read_timeout);
			stop_read();
			return -3;
		}
		tries++;
	} while (cd->intr_ds & ds_fifo_empty && tries < MAX_TRIES);
	if (tries > 1)
		debug(("Took me some tries\n"))
		    else
	if (tries == MAX_TRIES)
		debug(("MAX_TRIES tries for read sector\n"));
	transport_data(r_fifo_output_buffer, cd->sector,
		       READ_AHEAD * RAW_SECTOR_SIZE / 2);
	if (read_background(start + READ_AHEAD, 1))
		stats(read_background);
	cd->sector_first = start;
	cd->sector_last = start + READ_AHEAD;
	stats(read_restarted);
	return 0;
}

/* The function of bottom-half is to send a stop command to the drive
   This isn't easy because the routine is not `owned' by any process;
   we can't go to sleep! The variable cd->background gives the status:
   0 no read pending
   1 a read is pending
   2 c_stop waits for write_buffer_empty
   3 c_stop waits for receive_buffer_full: echo
   4 c_stop waits for receive_buffer_full: 0xff
*/

void cm206_bh(void)
{
	debug(("bh: %d\n", cd->background));
	switch (cd->background) {
	case 1:
		stats(bh);
		if (!(cd->intr_ls & ls_transmitter_buffer_empty)) {
			cd->command = c_stop;
			outw(dc_mask_sync_error | dc_no_stop_on_error |
			     (inw(r_data_status) & 0x7f), r_data_control);
			cd->background = 2;
			break;	/* we'd better not time-out here! */
		} else
			outw(c_stop, r_uart_transmit);
		/* fall into case 2: */
	case 2:
		/* the write has been satisfied by interrupt routine */
		cd->background = 3;
		break;
	case 3:
		if (cd->ur_r != cd->ur_w) {
			if (cd->ur[cd->ur_r] != c_stop) {
				debug(("cm206_bh: c_stop echoed 0x%x\n",
				       cd->ur[cd->ur_r]));
				stats(echo);
			}
			cd->ur_r++;
			cd->ur_r %= UR_SIZE;
		}
		cd->background++;
		break;
	case 4:
		if (cd->ur_r != cd->ur_w) {
			if (cd->ur[cd->ur_r] != 0xff) {
				debug(("cm206_bh: c_stop reacted with 0x%x\n", cd->ur[cd->ur_r]));
				stats(stop_0xff);
			}
			cd->ur_r++;
			cd->ur_r %= UR_SIZE;
		}
		cd->background = 0;
	}
}

/* This command clears the dsb_possible_media_change flag, so we must 
 * retain it.
 */
void get_drive_status(void)
{
	uch status[2];
	type_1_command(c_drive_status, 2, status);	/* this might be done faster */
	cd->dsb = status[0];
	cd->cc = status[1];
	cd->media_changed |=
	    !!(cd->dsb & (dsb_possible_media_change |
			  dsb_drive_not_ready | dsb_tray_not_closed));
}

void get_disc_status(void)
{
	if (type_1_command(c_disc_status, 7, cd->disc_status)) {
		debug(("get_disc_status: error\n"));
	}
}

struct block_device_operations cm206_bdops =
{
	owner:			THIS_MODULE,
	open:			cdrom_open,
	release:		cdrom_release,
	ioctl:			cdrom_ioctl,
	check_media_change:	cdrom_media_changed,
};

/* The new open. The real opening strategy is defined in cdrom.c. */

static int cm206_open(struct cdrom_device_info *cdi, int purpose)
{
	if (!cd->openfiles) {	/* reset only first time */
		cd->background = 0;
		reset_cm260();
		cd->adapter_last = -1;	/* invalidate adapter memory */
		cd->sector_last = -1;
	}
	++cd->openfiles;
	stats(open);
	return 0;
}

static void cm206_release(struct cdrom_device_info *cdi)
{
	if (cd->openfiles == 1) {
		if (cd->background) {
			cd->background = 0;
			stop_read();
		}
		cd->sector_last = -1;	/* Make our internal buffer invalid */
		FIRST_TRACK = 0;	/* No valid disc status */
	}
	--cd->openfiles;
}

/* Empty buffer empties $sectors$ sectors of the adapter card buffer,
 * and then reads a sector in kernel memory.  */
void empty_buffer(int sectors)
{
	while (sectors >= 0) {
		transport_data(r_fifo_output_buffer,
			       cd->sector + cd->fifo_overflowed,
			       RAW_SECTOR_SIZE / 2 - cd->fifo_overflowed);
		--sectors;
		++cd->adapter_first;	/* update the current adapter sector */
		cd->fifo_overflowed = 0;	/* reset overflow bit */
		stats(sector_transferred);
	}
	cd->sector_first = cd->adapter_first - 1;
	cd->sector_last = cd->adapter_first;	/* update the buffer sector */
}

/* try_adapter. This function determines if the requested sector is
   in adapter memory, or will appear there soon. Returns 0 upon
   success */
int try_adapter(int sector)
{
	if (cd->adapter_first <= sector && sector < cd->adapter_last) {
		/* sector is in adapter memory */
		empty_buffer(sector - cd->adapter_first);
		return 0;
	} else if (cd->background == 1 && cd->adapter_first <= sector
		   && sector < cd->adapter_first + cd->max_sectors) {
		/* a read is going on, we can wait for it */
		cd->wait_back = 1;
		while (sector >= cd->adapter_last) {
			if (sleep_or_timeout(&cd->data, DATA_TIMEOUT)) {
				debug(("Timed out during background wait: %d %d %d %d\n", sector, cd->adapter_last, cd->adapter_first, cd->background));
				stats(back_read_timeout);
				cd->wait_back = 0;
				return -1;
			}
		}
		cd->wait_back = 0;
		empty_buffer(sector - cd->adapter_first);
		return 0;
	} else
		return -2;
}

/* This is not a very smart implementation. We could optimize for 
   consecutive block numbers. I'm not convinced this would really
   bring down the processor load. */
static void do_cm206_request(request_queue_t * q)
{
	long int i, cd_sec_no;
	int quarter, error;
	uch *source, *dest;

	while (1) {		/* repeat until all requests have been satisfied */
		INIT_REQUEST;
		if (QUEUE_EMPTY || CURRENT->rq_status == RQ_INACTIVE)
			return;
		if (CURRENT->cmd != READ) {
			debug(("Non-read command %d on cdrom\n",
			       CURRENT->cmd));
			end_request(0);
			continue;
		}
		spin_unlock_irq(&io_request_lock);
		error = 0;
		for (i = 0; i < CURRENT->nr_sectors; i++) {
			int e1, e2;
			cd_sec_no = (CURRENT->sector + i) / BLOCKS_ISO;	/* 4 times 512 bytes */
			quarter = (CURRENT->sector + i) % BLOCKS_ISO;
			dest = CURRENT->buffer + i * LINUX_BLOCK_SIZE;
			/* is already in buffer memory? */
			if (cd->sector_first <= cd_sec_no
			    && cd_sec_no < cd->sector_last) {
				source =
				    ((uch *) cd->sector) + 16 +
				    quarter * LINUX_BLOCK_SIZE +
				    (cd_sec_no -
				     cd->sector_first) * RAW_SECTOR_SIZE;
				memcpy(dest, source, LINUX_BLOCK_SIZE);
			} else if (!(e1 = try_adapter(cd_sec_no)) ||
				   !(e2 = read_sector(cd_sec_no))) {
				source =
				    ((uch *) cd->sector) + 16 +
				    quarter * LINUX_BLOCK_SIZE;
				memcpy(dest, source, LINUX_BLOCK_SIZE);
			} else {
				error = 1;
				debug(("cm206_request: %d %d\n", e1, e2));
			}
		}
		spin_lock_irq(&io_request_lock);
		end_request(!error);
	}
}

/* Audio support. I've tried very hard, but the cm206 drive doesn't 
   seem to have a get_toc (table-of-contents) function, while i'm
   pretty sure it must read the toc upon disc insertion. Therefore
   this function has been implemented through a binary search 
   strategy. All track starts that happen to be found are stored in
   cd->toc[], for future use. 

   I've spent a whole day on a bug that only shows under Workman---
   I don't get it. Tried everything, nothing works. If workman asks
   for track# 0xaa, it'll get the wrong time back. Any other program
   receives the correct value. I'm stymied.
*/

/* seek seeks to address lba. It does wait to arrive there. */
void seek(int lba)
{
	int i;
	uch seek_command[4] = { c_seek, };

	fsm(lba, &seek_command[1]);
	for (i = 0; i < 4; i++)
		type_0_command(seek_command[i], 0);
	cd->dsb = wait_dsb();
}

uch bcdbin(unsigned char bcd)
{				/* stolen from mcd.c! */
	return (bcd >> 4) * 10 + (bcd & 0xf);
}

inline uch normalize_track(uch track)
{
	if (track < 1)
		return 1;
	if (track > LAST_TRACK)
		return LAST_TRACK + 1;
	return track;
}

/* This function does a binary search for track start. It records all
 * tracks seen in the process. Input $track$ must be between 1 and
 * #-of-tracks+1.  Note that the start of the disc must be in toc[1].fsm. 
 */
int get_toc_lba(uch track)
{
	int max = 74 * 60 * 75 - 150, min = fsm2lba(cd->toc[1].fsm);
	int i, lba, l, old_lba = 0;
	uch *q = cd->q;
	uch ct;			/* current track */
	int binary = 0;
	const int skip = 3 * 60 * 75;	/* 3 minutes */

	for (i = track; i > 0; i--)
		if (cd->toc[i].track) {
			min = fsm2lba(cd->toc[i].fsm);
			break;
		}
	lba = min + skip;
	do {
		seek(lba);
		type_1_command(c_read_current_q, 10, q);
		ct = normalize_track(q[1]);
		if (!cd->toc[ct].track) {
			l = q[9] - bcdbin(q[5]) + 75 * (q[8] -
							bcdbin(q[4]) - 2 +
							60 * (q[7] -
							      bcdbin(q
								     [3])));
			cd->toc[ct].track = q[1];	/* lead out still 0xaa */
			fsm(l, cd->toc[ct].fsm);
			cd->toc[ct].q0 = q[0];	/* contains adr and ctrl info */
			if (ct == track)
				return l;
		}
		old_lba = lba;
		if (binary) {
			if (ct < track)
				min = lba;
			else
				max = lba;
			lba = (min + max) / 2;
		} else {
			if (ct < track)
				lba += skip;
			else {
				binary = 1;
				max = lba;
				min = lba - skip;
				lba = (min + max) / 2;
			}
		}
	} while (lba != old_lba);
	return lba;
}

void update_toc_entry(uch track)
{
	track = normalize_track(track);
	if (!cd->toc[track].track)
		get_toc_lba(track);
}

/* return 0 upon success */
int read_toc_header(struct cdrom_tochdr *hp)
{
	if (!FIRST_TRACK)
		get_disc_status();
	if (hp) {
		int i;
		hp->cdth_trk0 = FIRST_TRACK;
		hp->cdth_trk1 = LAST_TRACK;
		/* fill in first track position */
		for (i = 0; i < 3; i++)
			cd->toc[1].fsm[i] = cd->disc_status[3 + i];
		update_toc_entry(LAST_TRACK + 1);	/* find most entries */
		return 0;
	}
	return -1;
}

void play_from_to_msf(struct cdrom_msf *msfp)
{
	uch play_command[] = { c_play,
		msfp->cdmsf_frame0, msfp->cdmsf_sec0, msfp->cdmsf_min0,
		msfp->cdmsf_frame1, msfp->cdmsf_sec1, msfp->cdmsf_min1, 2,
		    2
	};
	int i;
	for (i = 0; i < 9; i++)
		type_0_command(play_command[i], 0);
	for (i = 0; i < 3; i++)
		PLAY_TO.fsm[i] = play_command[i + 4];
	PLAY_TO.track = 0;	/* say no track end */
	cd->dsb = wait_dsb();
}

void play_from_to_track(int from, int to)
{
	uch play_command[8] = { c_play, };
	int i;

	if (from == 0) {	/* continue paused play */
		for (i = 0; i < 3; i++) {
			play_command[i + 1] = cd->audio_status[i + 2];
			play_command[i + 4] = PLAY_TO.fsm[i];
		}
	} else {
		update_toc_entry(from);
		update_toc_entry(to + 1);
		for (i = 0; i < 3; i++) {
			play_command[i + 1] = cd->toc[from].fsm[i];
			PLAY_TO.fsm[i] = play_command[i + 4] =
			    cd->toc[to + 1].fsm[i];
		}
		PLAY_TO.track = to;
	}
	for (i = 0; i < 7; i++)
		type_0_command(play_command[i], 0);
	for (i = 0; i < 2; i++)
		type_0_command(0x2, 0);	/* volume */