[PATCH] CDROMREADAUDIO dma support

This small patch builds on top of the blk_rq_map_user() patch just sent,
and enables us to easily support DMA for CDROMREADAUDIO cdda extraction.
It's quite amazing how much cool stuff you can with the new block layer
:-)

Patch has intelligent fall back from multi frame dma to single frame
dma, and further to old-style pio ripping in case of hardware problems.

drivers/cdrom/cdrom.c

@@ -406,6 +406,11 @@ int register_cdrom(struct cdrom_device_info *cdi)
 	if (CDROM_CAN(CDC_MRW_W))
 		cdi->exit = cdrom_mrw_exit;
 
+	if (cdi->disk)
+		cdi->cdda_method = CDDA_BPC_FULL;
+	else
+		cdi->cdda_method = CDDA_OLD;
+
 	cdinfo(CD_REG_UNREG, "drive \"/dev/%s\" registered\n", cdi->name);
 	spin_lock(&cdrom_lock);
 	cdi->next = topCdromPtr; 	
@@ -1788,6 +1793,149 @@ static int cdrom_read_block(struct cdrom_device_info *cdi,
 	return cdo->generic_packet(cdi, cgc);
 }
 
+static int cdrom_read_cdda_old(struct cdrom_device_info *cdi, __u8 __user *ubuf,
+			       int lba, int nframes)
+{
+	struct cdrom_generic_command cgc;
+	int nr, ret;
+
+	memset(&cgc, 0, sizeof(cgc));
+
+	/*
+	 * start with will ra.nframes size, back down if alloc fails
+	 */
+	nr = nframes;
+	do {
+		cgc.buffer = kmalloc(CD_FRAMESIZE_RAW * nr, GFP_KERNEL);
+		if (cgc.buffer)
+			break;
+
+		nr >>= 1;
+	} while (nr);
+
+	if (!nr)
+		return -ENOMEM;
+
+	if (!access_ok(VERIFY_WRITE, ubuf, nframes * CD_FRAMESIZE_RAW)) {
+		kfree(cgc.buffer);
+		return -EFAULT;
+	}
+
+	cgc.data_direction = CGC_DATA_READ;
+	while (nframes > 0) {
+		if (nr > nframes)
+			nr = nframes;
+
+		ret = cdrom_read_block(cdi, &cgc, lba, nr, 1, CD_FRAMESIZE_RAW);
+		if (ret)
+			break;
+		__copy_to_user(ubuf, cgc.buffer, CD_FRAMESIZE_RAW * nr);
+		ubuf += CD_FRAMESIZE_RAW * nr;
+		nframes -= nr;
+		lba += nr;
+	}
+	kfree(cgc.buffer);
+	return 0;
+}
+
+static int cdrom_read_cdda_bpc(struct cdrom_device_info *cdi, __u8 __user *ubuf,
+			       int lba, int nframes)
+{
+	request_queue_t *q = cdi->disk->queue;
+	struct request *rq;
+	unsigned int len;
+	int nr, ret = 0;
+
+	if (!q)
+		return -ENXIO;
+
+	while (nframes) {
+		nr = nframes;
+		if (cdi->cdda_method == CDDA_BPC_SINGLE)
+			nr = 1;
+		if (nr * CD_FRAMESIZE_RAW > (q->max_sectors << 9))
+			nr = (q->max_sectors << 9) / CD_FRAMESIZE_RAW;
+
+		len = nr * CD_FRAMESIZE_RAW;
+
+		rq = blk_rq_map_user(q, READ, ubuf, len);
+		if (IS_ERR(rq))
+			return PTR_ERR(rq);
+
+		memset(rq->cmd, 0, sizeof(rq->cmd));
+		rq->cmd[0] = GPCMD_READ_CD;
+		rq->cmd[1] = 1 << 2;
+		rq->cmd[2] = (lba >> 24) & 0xff;
+		rq->cmd[3] = (lba >> 16) & 0xff;
+		rq->cmd[4] = (lba >>  8) & 0xff;
+		rq->cmd[5] = lba & 0xff;
+		rq->cmd[6] = (nr >> 16) & 0xff;
+		rq->cmd[7] = (nr >>  8) & 0xff;
+		rq->cmd[8] = nr & 0xff;
+		rq->cmd[9] = 0xf8;
+
+		rq->cmd_len = 12;
+		rq->flags |= REQ_BLOCK_PC;
+		rq->timeout = 60 * HZ;
+
+		if (blk_execute_rq(q, cdi->disk, rq)) {
+			struct request_sense *s = rq->sense;
+			ret = -EIO;
+			cdi->last_sense = s->sense_key;
+		}
+
+		if (blk_rq_unmap_user(rq, ubuf, len))
+			ret = -EFAULT;
+
+		if (ret)
+			break;
+
+		nframes -= nr;
+		lba += nr;
+	}
+
+	return ret;
+}
+
+static int cdrom_read_cdda(struct cdrom_device_info *cdi, __u8 __user *ubuf,
+			   int lba, int nframes)
+{
+	int ret;
+
+	if (cdi->cdda_method == CDDA_OLD)
+		return cdrom_read_cdda_old(cdi, ubuf, lba, nframes);
+
+retry:
+	/*
+	 * for anything else than success and io error, we need to retry
+	 */
+	ret = cdrom_read_cdda_bpc(cdi, ubuf, lba, nframes);
+	if (!ret || ret != -EIO)
+		return ret;
+
+	/*
+	 * I've seen drives get sense 4/8/3 udma crc errors on multi
+	 * frame dma, so drop to single frame dma if we need to
+	 */
+	if (cdi->cdda_method == CDDA_BPC_FULL && nframes > 1) {
+		printk("cdrom: dropping to single frame dma\n");
+		cdi->cdda_method = CDDA_BPC_SINGLE;
+		goto retry;
+	}
+
+	/*
+	 * so we have an io error of some sort with multi frame dma. if the
+	 * condition wasn't a hardware error
+	 * problems, not for any error
+	 */
+	if (cdi->last_sense != 0x04 && cdi->last_sense != 0x0b)
+		return ret;
+
+	printk("cdrom: dropping to old style cdda (sense=%x)\n", cdi->last_sense);
+	cdi->cdda_method = CDDA_OLD;
+	return cdrom_read_cdda_old(cdi, ubuf, lba, nframes);	
+}
+
 /* Just about every imaginable ioctl is supported in the Uniform layer
  * these days. ATAPI / SCSI specific code now mainly resides in
  * mmc_ioct().
@@ -2280,7 +2428,7 @@ static int mmc_ioctl(struct cdrom_device_info *cdi, unsigned int cmd,
 		}
 	case CDROMREADAUDIO: {
 		struct cdrom_read_audio ra;
-		int lba, nr;
+		int lba;
 
 		IOCTL_IN(arg, struct cdrom_read_audio, ra);
 
@@ -2297,40 +2445,7 @@ static int mmc_ioctl(struct cdrom_device_info *cdi, unsigned int cmd,
 		if (lba < 0 || ra.nframes <= 0 || ra.nframes > CD_FRAMES)
 			return -EINVAL;
 
-		/*
-		 * start with will ra.nframes size, back down if alloc fails
-		 */
-		nr = ra.nframes;
-		do {
-			cgc.buffer = kmalloc(CD_FRAMESIZE_RAW * nr, GFP_KERNEL);
-			if (cgc.buffer)
-				break;
-
-			nr >>= 1;
-		} while (nr);
-
-		if (!nr)
-			return -ENOMEM;
-
-		if (!access_ok(VERIFY_WRITE, ra.buf, ra.nframes*CD_FRAMESIZE_RAW)) {
-			kfree(cgc.buffer);
-			return -EFAULT;
-		}
-		cgc.data_direction = CGC_DATA_READ;
-		while (ra.nframes > 0) {
-			if (nr > ra.nframes)
-				nr = ra.nframes;
-
-			ret = cdrom_read_block(cdi, &cgc, lba, nr, 1, CD_FRAMESIZE_RAW);
-			if (ret)
-				break;
-			__copy_to_user(ra.buf, cgc.buffer, CD_FRAMESIZE_RAW*nr);
-			ra.buf += CD_FRAMESIZE_RAW * nr;
-			ra.nframes -= nr;
-			lba += nr;
-		}
-		kfree(cgc.buffer);
-		return ret;
+		return cdrom_read_cdda(cdi, ra.buf, lba, ra.nframes);
 		}
 	case CDROMSUBCHNL: {
 		struct cdrom_subchnl q;

drivers/ide/ide-cd.c

@@ -2931,6 +2931,7 @@ static int ide_cdrom_register (ide_drive_t *drive, int nslots)
 	if (!CDROM_CONFIG_FLAGS(drive)->mrw_w)
 		devinfo->mask |= CDC_MRW_W;
 
+	devinfo->disk = drive->disk;
 	return register_cdrom(devinfo);
 }
 

drivers/scsi/sr.c

@@ -566,10 +566,13 @@ static int sr_probe(struct device *dev)
 	snprintf(disk->devfs_name, sizeof(disk->devfs_name),
 			"%s/cd", sdev->devfs_name);
 	disk->driverfs_dev = &sdev->sdev_gendev;
-	register_cdrom(&cd->cdi);
 	set_capacity(disk, cd->capacity);
 	disk->private_data = &cd->driver;
 	disk->queue = sdev->request_queue;
+	cd->cdi.disk = disk;
+
+	if (register_cdrom(&cd->cdi))
+		goto fail_put;
 
 	dev_set_drvdata(dev, cd);
 	add_disk(disk);

include/linux/cdrom.h

@@ -877,10 +877,18 @@ struct mode_page_header {
 #include <linux/fs.h>		/* not really needed, later.. */
 #include <linux/device.h>
 
+/*
+ * _OLD will use PIO transfer on atapi devices, _BPC_* will use DMA
+ */
+#define CDDA_OLD		0	/* old style */
+#define CDDA_BPC_SINGLE		1	/* single frame block pc */
+#define CDDA_BPC_FULL		2	/* multi frame block pc */
+
 /* Uniform cdrom data structures for cdrom.c */
 struct cdrom_device_info {
 	struct cdrom_device_ops  *ops;  /* link to device_ops */
 	struct cdrom_device_info *next; /* next device_info for this major */
+	struct gendisk *disk;		/* matching block layer disk */
 	void *handle;		        /* driver-dependent data */
 /* specifications */
 	int mask;                       /* mask of capability: disables them */
@@ -894,6 +902,8 @@ struct cdrom_device_info {
 /* per-device flags */
         __u8 sanyo_slot		: 2;	/* Sanyo 3 CD changer support */
         __u8 reserved		: 6;	/* not used yet */
+	int cdda_method;		/* see flags */
+	__u8 last_sense;
 	int for_data;
 	int (*exit)(struct cdrom_device_info *);
 	int mrw_mode_page;