block: add VirtIO block device driver

With this driver enabled, -device virtio-blk-device can now be passed
to Qemu for barebox to detect a VirtIO block device mapping a host
file or block device.

If barebox is passed as argument to the Qemu -kernel option, no device
tree changes are necessary.

Example:

  $ qemu-system-arm -m 256M -M virt -nographic                  \
  	-kernel build/images/barebox-dt-2nd.img                 \
  	-device virtio-rng-device                               \
  	-drive if=none,file=/tmp/first.hdimg,format=raw,id=hd0  \
  	-device virtio-blk-device,drive=hd0                     \
  	-drive if=none,file=/tmp/second.hdimg,format=raw,id=hd1 \
  	-device virtio-blk-device,drive=hd1

Signed-off-by: Ahmad Fatoum <ahmad@a3f.at>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 203 insertions, 0 deletions

diff --git a/include/uapi/linux/virtio_blk.h b/include/uapi/linux/virtio_blk.h
new file mode 100644
index 0000000000..d888f013d9
--- /dev/null
+++ b/include/uapi/linux/virtio_blk.h
@@ -0,0 +1,203 @@
+#ifndef _LINUX_VIRTIO_BLK_H
+#define _LINUX_VIRTIO_BLK_H
+/* This header is BSD licensed so anyone can use the definitions to implement
+ * compatible drivers/servers.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of IBM nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL IBM OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE. */
+#include <linux/types.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+#include <linux/virtio_types.h>
+
+/* Feature bits */
+#define VIRTIO_BLK_F_SIZE_MAX	1	/* Indicates maximum segment size */
+#define VIRTIO_BLK_F_SEG_MAX	2	/* Indicates maximum # of segments */
+#define VIRTIO_BLK_F_GEOMETRY	4	/* Legacy geometry available  */
+#define VIRTIO_BLK_F_RO		5	/* Disk is read-only */
+#define VIRTIO_BLK_F_BLK_SIZE	6	/* Block size of disk is available*/
+#define VIRTIO_BLK_F_TOPOLOGY	10	/* Topology information is available */
+#define VIRTIO_BLK_F_MQ		12	/* support more than one vq */
+#define VIRTIO_BLK_F_DISCARD	13	/* DISCARD is supported */
+#define VIRTIO_BLK_F_WRITE_ZEROES	14	/* WRITE ZEROES is supported */
+
+/* Legacy feature bits */
+#ifndef VIRTIO_BLK_NO_LEGACY
+#define VIRTIO_BLK_F_BARRIER	0	/* Does host support barriers? */
+#define VIRTIO_BLK_F_SCSI	7	/* Supports scsi command passthru */
+#define VIRTIO_BLK_F_FLUSH	9	/* Flush command supported */
+#define VIRTIO_BLK_F_CONFIG_WCE	11	/* Writeback mode available in config */
+#ifndef __KERNEL__
+/* Old (deprecated) name for VIRTIO_BLK_F_FLUSH. */
+#define VIRTIO_BLK_F_WCE VIRTIO_BLK_F_FLUSH
+#endif
+#endif /* !VIRTIO_BLK_NO_LEGACY */
+
+#define VIRTIO_BLK_ID_BYTES	20	/* ID string length */
+
+struct virtio_blk_config {
+	/* The capacity (in 512-byte sectors). */
+	__virtio64 capacity;
+	/* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
+	__virtio32 size_max;
+	/* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
+	__virtio32 seg_max;
+	/* geometry of the device (if VIRTIO_BLK_F_GEOMETRY) */
+	struct virtio_blk_geometry {
+		__virtio16 cylinders;
+		__u8 heads;
+		__u8 sectors;
+	} geometry;
+
+	/* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
+	__virtio32 blk_size;
+
+	/* the next 4 entries are guarded by VIRTIO_BLK_F_TOPOLOGY  */
+	/* exponent for physical block per logical block. */
+	__u8 physical_block_exp;
+	/* alignment offset in logical blocks. */
+	__u8 alignment_offset;
+	/* minimum I/O size without performance penalty in logical blocks. */
+	__virtio16 min_io_size;
+	/* optimal sustained I/O size in logical blocks. */
+	__virtio32 opt_io_size;
+
+	/* writeback mode (if VIRTIO_BLK_F_CONFIG_WCE) */
+	__u8 wce;
+	__u8 unused;
+
+	/* number of vqs, only available when VIRTIO_BLK_F_MQ is set */
+	__virtio16 num_queues;
+
+	/* the next 3 entries are guarded by VIRTIO_BLK_F_DISCARD */
+	/*
+	 * The maximum discard sectors (in 512-byte sectors) for
+	 * one segment.
+	 */
+	__virtio32 max_discard_sectors;
+	/*
+	 * The maximum number of discard segments in a
+	 * discard command.
+	 */
+	__virtio32 max_discard_seg;
+	/* Discard commands must be aligned to this number of sectors. */
+	__virtio32 discard_sector_alignment;
+
+	/* the next 3 entries are guarded by VIRTIO_BLK_F_WRITE_ZEROES */
+	/*
+	 * The maximum number of write zeroes sectors (in 512-byte sectors) in
+	 * one segment.
+	 */
+	__virtio32 max_write_zeroes_sectors;
+	/*
+	 * The maximum number of segments in a write zeroes
+	 * command.
+	 */
+	__virtio32 max_write_zeroes_seg;
+	/*
+	 * Set if a VIRTIO_BLK_T_WRITE_ZEROES request may result in the
+	 * deallocation of one or more of the sectors.
+	 */
+	__u8 write_zeroes_may_unmap;
+
+	__u8 unused1[3];
+} __attribute__((packed));
+
+/*
+ * Command types
+ *
+ * Usage is a bit tricky as some bits are used as flags and some are not.
+ *
+ * Rules:
+ *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
+ *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
+ *   and may not be combined with any of the other flags.
+ */
+
+/* These two define direction. */
+#define VIRTIO_BLK_T_IN		0
+#define VIRTIO_BLK_T_OUT	1
+
+#ifndef VIRTIO_BLK_NO_LEGACY
+/* This bit says it's a scsi command, not an actual read or write. */
+#define VIRTIO_BLK_T_SCSI_CMD	2
+#endif /* VIRTIO_BLK_NO_LEGACY */
+
+/* Cache flush command */
+#define VIRTIO_BLK_T_FLUSH	4
+
+/* Get device ID command */
+#define VIRTIO_BLK_T_GET_ID    8
+
+/* Discard command */
+#define VIRTIO_BLK_T_DISCARD	11
+
+/* Write zeroes command */
+#define VIRTIO_BLK_T_WRITE_ZEROES	13
+
+#ifndef VIRTIO_BLK_NO_LEGACY
+/* Barrier before this op. */
+#define VIRTIO_BLK_T_BARRIER	0x80000000
+#endif /* !VIRTIO_BLK_NO_LEGACY */
+
+/*
+ * This comes first in the read scatter-gather list.
+ * For legacy virtio, if VIRTIO_F_ANY_LAYOUT is not negotiated,
+ * this is the first element of the read scatter-gather list.
+ */
+struct virtio_blk_outhdr {
+	/* VIRTIO_BLK_T* */
+	__virtio32 type;
+	/* io priority. */
+	__virtio32 ioprio;
+	/* Sector (ie. 512 byte offset) */
+	__virtio64 sector;
+};
+
+/* Unmap this range (only valid for write zeroes command) */
+#define VIRTIO_BLK_WRITE_ZEROES_FLAG_UNMAP	0x00000001
+
+/* Discard/write zeroes range for each request. */
+struct virtio_blk_discard_write_zeroes {
+	/* discard/write zeroes start sector */
+	__le64 sector;
+	/* number of discard/write zeroes sectors */
+	__le32 num_sectors;
+	/* flags for this range */
+	__le32 flags;
+};
+
+#ifndef VIRTIO_BLK_NO_LEGACY
+struct virtio_scsi_inhdr {
+	__virtio32 errors;
+	__virtio32 data_len;
+	__virtio32 sense_len;
+	__virtio32 residual;
+};
+#endif /* !VIRTIO_BLK_NO_LEGACY */
+
+/* And this is the final byte of the write scatter-gather list. */
+#define VIRTIO_BLK_S_OK		0
+#define VIRTIO_BLK_S_IOERR	1
+#define VIRTIO_BLK_S_UNSUPP	2
+#endif /* _LINUX_VIRTIO_BLK_H */