virtio: Add block driver support

This adds virtio block device driver support.

Signed-off-by: Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/virtio/Kconfig

@@ -36,4 +36,11 @@ config VIRTIO_NET
 	  This is the virtual net driver for virtio. It can be used with
 	  QEMU based targets.
 
+config VIRTIO_BLK
+	bool "virtio block driver"
+	depends on VIRTIO
+	help
+	  This is the virtual block driver for virtio. It can be used with
+	  QEMU based targets.
+
 endmenu

drivers/virtio/Makefile

@@ -6,3 +6,4 @@
 obj-y += virtio-uclass.o virtio_ring.o
 obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
 obj-$(CONFIG_VIRTIO_NET) += virtio_net.o
+obj-$(CONFIG_VIRTIO_BLK) += virtio_blk.o

drivers/virtio/virtio_blk.c

@@ -0,0 +1,137 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ */
+
+#include <common.h>
+#include <blk.h>
+#include <dm.h>
+#include <virtio_types.h>
+#include <virtio.h>
+#include <virtio_ring.h>
+#include "virtio_blk.h"
+
+struct virtio_blk_priv {
+	struct virtqueue *vq;
+};
+
+static ulong virtio_blk_do_req(struct udevice *dev, u64 sector,
+			       lbaint_t blkcnt, void *buffer, u32 type)
+{
+	struct virtio_blk_priv *priv = dev_get_priv(dev);
+	unsigned int num_out = 0, num_in = 0;
+	struct virtio_sg *sgs[3];
+	u8 status;
+	int ret;
+
+	struct virtio_blk_outhdr out_hdr = {
+		.type = cpu_to_virtio32(dev, type),
+		.sector = cpu_to_virtio64(dev, sector),
+	};
+	struct virtio_sg hdr_sg = { &out_hdr, sizeof(out_hdr) };
+	struct virtio_sg data_sg = { buffer, blkcnt * 512 };
+	struct virtio_sg status_sg = { &status, sizeof(status) };
+
+	sgs[num_out++] = &hdr_sg;
+
+	if (type & VIRTIO_BLK_T_OUT)
+		sgs[num_out++] = &data_sg;
+	else
+		sgs[num_out + num_in++] = &data_sg;
+
+	sgs[num_out + num_in++] = &status_sg;
+
+	ret = virtqueue_add(priv->vq, sgs, num_out, num_in);
+	if (ret)
+		return ret;
+
+	virtqueue_kick(priv->vq);
+
+	while (!virtqueue_get_buf(priv->vq, NULL))
+		;
+
+	return status == VIRTIO_BLK_S_OK ? blkcnt : -EIO;
+}
+
+static ulong virtio_blk_read(struct udevice *dev, lbaint_t start,
+			     lbaint_t blkcnt, void *buffer)
+{
+	return virtio_blk_do_req(dev, start, blkcnt, buffer,
+				 VIRTIO_BLK_T_IN);
+}
+
+static ulong virtio_blk_write(struct udevice *dev, lbaint_t start,
+			      lbaint_t blkcnt, const void *buffer)
+{
+	return virtio_blk_do_req(dev, start, blkcnt, (void *)buffer,
+				 VIRTIO_BLK_T_OUT);
+}
+
+static int virtio_blk_bind(struct udevice *dev)
+{
+	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(dev->parent);
+	struct blk_desc *desc = dev_get_uclass_platdata(dev);
+	int devnum;
+
+	desc->if_type = IF_TYPE_VIRTIO;
+	/*
+	 * Initialize the devnum to -ENODEV. This is to make sure that
+	 * blk_next_free_devnum() works as expected, since the default
+	 * value 0 is a valid devnum.
+	 */
+	desc->devnum = -ENODEV;
+	devnum = blk_next_free_devnum(IF_TYPE_VIRTIO);
+	if (devnum < 0)
+		return devnum;
+	desc->devnum = devnum;
+	desc->part_type = PART_TYPE_UNKNOWN;
+	/*
+	 * virtio mmio transport supplies string identification for us,
+	 * while pci trnasport uses a 2-byte subvendor value.
+	 */
+	if (uc_priv->vendor >> 16)
+		sprintf(desc->vendor, "%s", (char *)&uc_priv->vendor);
+	else
+		sprintf(desc->vendor, "%04x", uc_priv->vendor);
+	desc->bdev = dev;
+
+	/* Indicate what driver features we support */
+	virtio_driver_features_init(uc_priv, NULL, 0, NULL, 0);
+
+	return 0;
+}
+
+static int virtio_blk_probe(struct udevice *dev)
+{
+	struct virtio_blk_priv *priv = dev_get_priv(dev);
+	struct blk_desc *desc = dev_get_uclass_platdata(dev);
+	u64 cap;
+	int ret;
+
+	ret = virtio_find_vqs(dev, 1, &priv->vq);
+	if (ret)
+		return ret;
+
+	desc->blksz = 512;
+	virtio_cread(dev, struct virtio_blk_config, capacity, &cap);
+	desc->lba = cap;
+
+	return 0;
+}
+
+static const struct blk_ops virtio_blk_ops = {
+	.read	= virtio_blk_read,
+	.write	= virtio_blk_write,
+};
+
+U_BOOT_DRIVER(virtio_blk) = {
+	.name	= VIRTIO_BLK_DRV_NAME,
+	.id	= UCLASS_BLK,
+	.ops	= &virtio_blk_ops,
+	.bind	= virtio_blk_bind,
+	.probe	= virtio_blk_probe,
+	.remove	= virtio_reset,
+	.priv_auto_alloc_size = sizeof(struct virtio_blk_priv),
+	.flags	= DM_FLAG_ACTIVE_DMA,
+};

drivers/virtio/virtio_blk.h

@@ -0,0 +1,129 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+/*
+ * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ *
+ * From Linux kernel include/uapi/linux/virtio_blk.h
+ */
+
+#ifndef _LINUX_VIRTIO_BLK_H
+#define _LINUX_VIRTIO_BLK_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 */
+
+/* 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 __packed virtio_blk_config {
+	/* The capacity (in 512-byte sectors) */
+	__u64 capacity;
+	/* The maximum segment size (if VIRTIO_BLK_F_SIZE_MAX) */
+	__u32 size_max;
+	/* The maximum number of segments (if VIRTIO_BLK_F_SEG_MAX) */
+	__u32 seg_max;
+	/* geometry of the device (if VIRTIO_BLK_F_GEOMETRY) */
+	struct virtio_blk_geometry {
+		__u16 cylinders;
+		__u8 heads;
+		__u8 sectors;
+	} geometry;
+
+	/* block size of device (if VIRTIO_BLK_F_BLK_SIZE) */
+	__u32 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 */
+	__u16 min_io_size;
+	/* optimal sustained I/O size in logical blocks */
+	__u32 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 */
+	__u16 num_queues;
+};
+
+/*
+ * 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
+
+#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;
+};
+
+#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 */