dm: Add a new uclass driver for VirtIO transport devices

This adds a new virtio uclass driver for “virtio” [1] family of
devices that are are found in virtual environments like QEMU,
yet by design they look like physical devices to the guest.

The uclass driver provides child_pre_probe() and child_post_probe()
methods to do some common operations for virtio device drivers like
device and driver supported feature negotiation, etc.

[1] http://docs.oasis-open.org/virtio/virtio/v1.0/virtio-v1.0.pdf

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/Kconfig

@@ -112,6 +112,8 @@ source "drivers/usb/Kconfig"
 
 source "drivers/video/Kconfig"
 
+source "drivers/virtio/Kconfig"
+
 source "drivers/w1/Kconfig"
 
 source "drivers/w1-eeprom/Kconfig"

drivers/Makefile

@@ -14,6 +14,7 @@ obj-$(CONFIG_$(SPL_TPL_)SERIAL_SUPPORT) += serial/
 obj-$(CONFIG_$(SPL_TPL_)SPI_FLASH_SUPPORT) += mtd/spi/
 obj-$(CONFIG_$(SPL_TPL_)SPI_SUPPORT) += spi/
 obj-$(CONFIG_$(SPL_TPL_)TIMER) += timer/
+obj-$(CONFIG_$(SPL_TPL_)VIRTIO) += virtio/
 obj-$(CONFIG_$(SPL_)DM_MAILBOX) += mailbox/
 obj-$(CONFIG_$(SPL_)REMOTEPROC) += remoteproc/
 

drivers/virtio/Kconfig

@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+# Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+#
+# VirtIO is a virtualization standard for network and disk device drivers
+# where just the guest's device driver "knows" it is running in a virtual
+# environment, and cooperates with the hypervisor. This enables guests to
+# get high performance network and disk operations, and gives most of the
+# performance benefits of paravirtualization. In the U-Boot case, the guest
+# is U-Boot itself, while the virtual environment are normally QEMU targets
+# like ARM, RISC-V and x86.
+#
+# See http://docs.oasis-open.org/virtio/virtio/v1.0/virtio-v1.0.pdf for
+# the VirtIO specification v1.0.
+
+menu "VirtIO Drivers"
+
+config VIRTIO
+	bool
+	help
+	  This option is selected by any driver which implements the virtio
+	  transport, such as CONFIG_VIRTIO_MMIO or CONFIG_VIRTIO_PCI.
+
+endmenu

drivers/virtio/Makefile

@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+# Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+
+obj-y += virtio-uclass.o

drivers/virtio/virtio-uclass.c

@@ -0,0 +1,369 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ *
+ * VirtIO is a virtualization standard for network and disk device drivers
+ * where just the guest's device driver "knows" it is running in a virtual
+ * environment, and cooperates with the hypervisor. This enables guests to
+ * get high performance network and disk operations, and gives most of the
+ * performance benefits of paravirtualization. In the U-Boot case, the guest
+ * is U-Boot itself, while the virtual environment are normally QEMU targets
+ * like ARM, RISC-V and x86.
+ *
+ * See http://docs.oasis-open.org/virtio/virtio/v1.0/virtio-v1.0.pdf for
+ * the VirtIO specification v1.0.
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <virtio_types.h>
+#include <virtio.h>
+#include <dm/lists.h>
+
+static const char *const virtio_drv_name[VIRTIO_ID_MAX_NUM] = {
+	[VIRTIO_ID_NET]		= VIRTIO_NET_DRV_NAME,
+	[VIRTIO_ID_BLOCK]	= VIRTIO_BLK_DRV_NAME,
+};
+
+int virtio_get_config(struct udevice *vdev, unsigned int offset,
+		      void *buf, unsigned int len)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->get_config(vdev->parent, offset, buf, len);
+}
+
+int virtio_set_config(struct udevice *vdev, unsigned int offset,
+		      void *buf, unsigned int len)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->set_config(vdev->parent, offset, buf, len);
+}
+
+int virtio_generation(struct udevice *vdev, u32 *counter)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+	if (!ops->generation)
+		return -ENOSYS;
+
+	return ops->generation(vdev->parent, counter);
+}
+
+int virtio_get_status(struct udevice *vdev, u8 *status)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->get_status(vdev->parent, status);
+}
+
+int virtio_set_status(struct udevice *vdev, u8 status)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->set_status(vdev->parent, status);
+}
+
+int virtio_reset(struct udevice *vdev)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->reset(vdev->parent);
+}
+
+int virtio_get_features(struct udevice *vdev, u64 *features)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->get_features(vdev->parent, features);
+}
+
+int virtio_set_features(struct udevice *vdev)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->set_features(vdev->parent);
+}
+
+int virtio_find_vqs(struct udevice *vdev, unsigned int nvqs,
+		    struct virtqueue *vqs[])
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->find_vqs(vdev->parent, nvqs, vqs);
+}
+
+int virtio_del_vqs(struct udevice *vdev)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->del_vqs(vdev->parent);
+}
+
+int virtio_notify(struct udevice *vdev, struct virtqueue *vq)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = virtio_get_ops(vdev->parent);
+
+	return ops->notify(vdev->parent, vq);
+}
+
+void virtio_add_status(struct udevice *vdev, u8 status)
+{
+	u8 old;
+
+	if (!virtio_get_status(vdev, &old))
+		virtio_set_status(vdev, old | status);
+}
+
+int virtio_finalize_features(struct udevice *vdev)
+{
+	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(vdev->parent);
+	u8 status;
+	int ret;
+
+	ret = virtio_set_features(vdev);
+	if (ret)
+		return ret;
+
+	if (uc_priv->legacy)
+		return 0;
+
+	virtio_add_status(vdev, VIRTIO_CONFIG_S_FEATURES_OK);
+	ret = virtio_get_status(vdev, &status);
+	if (ret)
+		return ret;
+	if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
+		debug("(%s): device refuses features %x\n", vdev->name, status);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+void virtio_driver_features_init(struct virtio_dev_priv *priv,
+				 const u32 *feature,
+				 u32 feature_size,
+				 const u32 *feature_legacy,
+				 u32 feature_legacy_size)
+{
+	priv->feature_table = feature;
+	priv->feature_table_size = feature_size;
+	priv->feature_table_legacy = feature_legacy;
+	priv->feature_table_size_legacy = feature_legacy_size;
+}
+
+int virtio_init(void)
+{
+	struct udevice *bus;
+	int ret;
+
+	/* Enumerate all known virtio devices */
+	ret = uclass_first_device(UCLASS_VIRTIO, &bus);
+	if (ret)
+		return ret;
+
+	while (bus) {
+		ret = uclass_next_device(&bus);
+		if (ret)
+			break;
+	}
+
+	return ret;
+}
+
+static int virtio_uclass_pre_probe(struct udevice *udev)
+{
+	struct dm_virtio_ops *ops;
+
+	ops = (struct dm_virtio_ops *)(udev->driver->ops);
+
+	/*
+	 * Check virtio transport driver ops here so that we don't need
+	 * check these ops each time when the virtio_xxx APIs are called.
+	 *
+	 * Only generation op is optional. All other ops are must-have.
+	 */
+	if (!ops->get_config || !ops->set_config ||
+	    !ops->get_status || !ops->set_status ||
+	    !ops->get_features || !ops->set_features ||
+	    !ops->find_vqs || !ops->del_vqs ||
+	    !ops->reset || !ops->notify)
+		return -ENOENT;
+
+	return 0;
+}
+
+static int virtio_uclass_post_probe(struct udevice *udev)
+{
+	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+	char dev_name[30], *str;
+	struct udevice *vdev;
+	int ret;
+
+	if (uc_priv->device > VIRTIO_ID_MAX_NUM) {
+		debug("(%s): virtio device ID %d exceeds maximum num\n",
+		      udev->name, uc_priv->device);
+		return 0;
+	}
+
+	if (!virtio_drv_name[uc_priv->device]) {
+		debug("(%s): underlying virtio device driver unavailable\n",
+		      udev->name);
+		return 0;
+	}
+
+	snprintf(dev_name, sizeof(dev_name), "%s#%d",
+		 virtio_drv_name[uc_priv->device], udev->seq);
+	str = strdup(dev_name);
+	if (!str)
+		return -ENOMEM;
+
+	ret = device_bind_driver(udev, virtio_drv_name[uc_priv->device],
+				 str, &vdev);
+	if (ret == -ENOENT) {
+		debug("(%s): no driver configured\n", udev->name);
+		return 0;
+	}
+	if (ret) {
+		free(str);
+		return ret;
+	}
+	device_set_name_alloced(vdev);
+
+	INIT_LIST_HEAD(&uc_priv->vqs);
+
+	return 0;
+}
+
+static int virtio_uclass_child_post_bind(struct udevice *vdev)
+{
+	/* Acknowledge that we've seen the device */
+	virtio_add_status(vdev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+
+	return 0;
+}
+
+static int virtio_uclass_child_pre_probe(struct udevice *vdev)
+{
+	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(vdev->parent);
+	u64 device_features;
+	u64 driver_features;
+	u64 driver_features_legacy;
+	int i;
+	int ret;
+
+	/*
+	 * Save the real virtio device (eg: virtio-net, virtio-blk) to
+	 * the transport (parent) device's uclass priv for future use.
+	 */
+	uc_priv->vdev = vdev;
+
+	/*
+	 * We always start by resetting the device, in case a previous driver
+	 * messed it up. This also tests that code path a little.
+	 */
+	ret = virtio_reset(vdev);
+	if (ret)
+		goto err;
+
+	/* We have a driver! */
+	virtio_add_status(vdev, VIRTIO_CONFIG_S_DRIVER);
+
+	/* Figure out what features the device supports */
+	virtio_get_features(vdev, &device_features);
+	debug("(%s) plain device features supported %016llx\n",
+	      vdev->name, device_features);
+	if (!(device_features & (1ULL << VIRTIO_F_VERSION_1)))
+		uc_priv->legacy = true;
+
+	/* Figure out what features the driver supports */
+	driver_features = 0;
+	for (i = 0; i < uc_priv->feature_table_size; i++) {
+		unsigned int f = uc_priv->feature_table[i];
+
+		WARN_ON(f >= 64);
+		driver_features |= (1ULL << f);
+	}
+
+	/* Some drivers have a separate feature table for virtio v1.0 */
+	if (uc_priv->feature_table_legacy) {
+		driver_features_legacy = 0;
+		for (i = 0; i < uc_priv->feature_table_size_legacy; i++) {
+			unsigned int f = uc_priv->feature_table_legacy[i];
+
+			WARN_ON(f >= 64);
+			driver_features_legacy |= (1ULL << f);
+		}
+	} else {
+		driver_features_legacy = driver_features;
+	}
+
+	if (uc_priv->legacy) {
+		debug("(%s): legacy virtio device\n", vdev->name);
+		uc_priv->features = driver_features_legacy & device_features;
+	} else {
+		debug("(%s): v1.0 complaint virtio device\n", vdev->name);
+		uc_priv->features = driver_features & device_features;
+	}
+
+	/* Transport features always preserved to pass to finalize_features */
+	for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
+		if ((device_features & (1ULL << i)) &&
+		    (i == VIRTIO_F_VERSION_1))
+			__virtio_set_bit(vdev->parent, i);
+
+	debug("(%s) final negotiated features supported %016llx\n",
+	      vdev->name, uc_priv->features);
+	ret = virtio_finalize_features(vdev);
+	if (ret)
+		goto err;
+
+	return 0;
+
+err:
+	virtio_add_status(vdev, VIRTIO_CONFIG_S_FAILED);
+	return ret;
+}
+
+static int virtio_uclass_child_post_probe(struct udevice *vdev)
+{
+	/* Indicates that the driver is set up and ready to drive the device */
+	virtio_add_status(vdev, VIRTIO_CONFIG_S_DRIVER_OK);
+
+	return 0;
+}
+
+UCLASS_DRIVER(virtio) = {
+	.name	= "virtio",
+	.id	= UCLASS_VIRTIO,
+	.flags	= DM_UC_FLAG_SEQ_ALIAS,
+	.pre_probe = virtio_uclass_pre_probe,
+	.post_probe = virtio_uclass_post_probe,
+	.child_post_bind = virtio_uclass_child_post_bind,
+	.child_pre_probe = virtio_uclass_child_pre_probe,
+	.child_post_probe = virtio_uclass_child_post_probe,
+	.per_device_auto_alloc_size = sizeof(struct virtio_dev_priv),
+};

include/dm/uclass-id.h

@@ -96,6 +96,7 @@ enum uclass_id {
 	UCLASS_VIDEO_BRIDGE,	/* Video bridge, e.g. DisplayPort to LVDS */
 	UCLASS_VIDEO_CONSOLE,	/* Text console driver for video device */
 	UCLASS_VIDEO_OSD,	/* On-screen display */
+	UCLASS_VIRTIO,		/* VirtIO transport device */
 	UCLASS_W1,		/* Dallas 1-Wire bus */
 	UCLASS_W1_EEPROM,	/* one-wire EEPROMs */
 	UCLASS_WDT,		/* Watchdot Timer driver */

include/virtio.h

@@ -0,0 +1,707 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2018, Tuomas Tynkkynen <tuomas.tynkkynen@iki.fi>
+ * Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
+ *
+ * VirtIO is a virtualization standard for network and disk device drivers
+ * where just the guest's device driver "knows" it is running in a virtual
+ * environment, and cooperates with the hypervisor. This enables guests to
+ * get high performance network and disk operations, and gives most of the
+ * performance benefits of paravirtualization. In the U-Boot case, the guest
+ * is U-Boot itself, while the virtual environment are normally QEMU targets
+ * like ARM, RISC-V and x86.
+ *
+ * See http://docs.oasis-open.org/virtio/virtio/v1.0/virtio-v1.0.pdf for
+ * the VirtIO specification v1.0.
+ *
+ * This file is largely based on Linux kernel virtio_*.h files
+ */
+
+#ifndef __VIRTIO_H__
+#define __VIRTIO_H__
+
+#define VIRTIO_ID_NET		1 /* virtio net */
+#define VIRTIO_ID_BLOCK		2 /* virtio block */
+#define VIRTIO_ID_MAX_NUM	3
+
+#define VIRTIO_NET_DRV_NAME	"virtio-net"
+#define VIRTIO_BLK_DRV_NAME	"virtio-blk"
+
+/* Status byte for guest to report progress, and synchronize features */
+
+/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
+#define VIRTIO_CONFIG_S_ACKNOWLEDGE	1
+/* We have found a driver for the device */
+#define VIRTIO_CONFIG_S_DRIVER		2
+/* Driver has used its parts of the config, and is happy */
+#define VIRTIO_CONFIG_S_DRIVER_OK	4
+/* Driver has finished configuring features */
+#define VIRTIO_CONFIG_S_FEATURES_OK	8
+/* Device entered invalid state, driver must reset it */
+#define VIRTIO_CONFIG_S_NEEDS_RESET	0x40
+/* We've given up on this device */
+#define VIRTIO_CONFIG_S_FAILED		0x80
+
+/*
+ * Virtio feature bits VIRTIO_TRANSPORT_F_START through VIRTIO_TRANSPORT_F_END
+ * are reserved for the transport being used (eg: virtio_ring, virtio_pci etc.),
+ * the rest are per-device feature bits.
+ */
+#define VIRTIO_TRANSPORT_F_START	28
+#define VIRTIO_TRANSPORT_F_END		38
+
+#ifndef VIRTIO_CONFIG_NO_LEGACY
+/*
+ * Do we get callbacks when the ring is completely used,
+ * even if we've suppressed them?
+ */
+#define VIRTIO_F_NOTIFY_ON_EMPTY	24
+
+/* Can the device handle any descriptor layout? */
+#define VIRTIO_F_ANY_LAYOUT		27
+#endif /* VIRTIO_CONFIG_NO_LEGACY */
+
+/* v1.0 compliant */
+#define VIRTIO_F_VERSION_1		32
+
+/*
+ * If clear - device has the IOMMU bypass quirk feature.
+ * If set - use platform tools to detect the IOMMU.
+ *
+ * Note the reverse polarity (compared to most other features),
+ * this is for compatibility with legacy systems.
+ */
+#define VIRTIO_F_IOMMU_PLATFORM		33
+
+/* Does the device support Single Root I/O Virtualization? */
+#define VIRTIO_F_SR_IOV			37
+
+/**
+ * virtio scatter-gather struct
+ *
+ * @addr:		sg buffer address
+ * @lengh:		sg buffer length
+ */
+struct virtio_sg {
+	void *addr;
+	size_t length;
+};
+
+struct virtqueue;
+
+/* virtio bus operations */
+struct dm_virtio_ops {
+	/**
+	 * get_config() - read the value of a configuration field
+	 *
+	 * @vdev:	the real virtio device
+	 * @offset:	the offset of the configuration field
+	 * @buf:	the buffer to write the field value into
+	 * @len:	the length of the buffer
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*get_config)(struct udevice *vdev, unsigned int offset,
+			  void *buf, unsigned int len);
+	/**
+	 * set_config() - write the value of a configuration field
+	 *
+	 * @vdev:	the real virtio device
+	 * @offset:	the offset of the configuration field
+	 * @buf:	the buffer to read the field value from
+	 * @len:	the length of the buffer
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*set_config)(struct udevice *vdev, unsigned int offset,
+			  const void *buf, unsigned int len);
+	/**
+	 * generation() - config generation counter
+	 *
+	 * @vdev:	the real virtio device
+	 * @counter:	the returned config generation counter
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*generation)(struct udevice *vdev, u32 *counter);
+	/**
+	 * get_status() - read the status byte
+	 *
+	 * @vdev:	the real virtio device
+	 * @status:	the returned status byte
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*get_status)(struct udevice *vdev, u8 *status);
+	/**
+	 * set_status() - write the status byte
+	 *
+	 * @vdev:	the real virtio device
+	 * @status:	the new status byte
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*set_status)(struct udevice *vdev, u8 status);
+	/**
+	 * reset() - reset the device
+	 *
+	 * @vdev:	the real virtio device
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*reset)(struct udevice *vdev);
+	/**
+	 * get_features() - get the array of feature bits for this device
+	 *
+	 * @vdev:	the real virtio device
+	 * @features:	the first 32 feature bits (all we currently need)
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*get_features)(struct udevice *vdev, u64 *features);
+	/**
+	 * set_features() - confirm what device features we'll be using
+	 *
+	 * @vdev:	the real virtio device
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*set_features)(struct udevice *vdev);
+	/**
+	 * find_vqs() - find virtqueues and instantiate them
+	 *
+	 * @vdev:	the real virtio device
+	 * @nvqs:	the number of virtqueues to find
+	 * @vqs:	on success, includes new virtqueues
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*find_vqs)(struct udevice *vdev, unsigned int nvqs,
+			struct virtqueue *vqs[]);
+	/**
+	 * del_vqs() - free virtqueues found by find_vqs()
+	 *
+	 * @vdev:	the real virtio device
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*del_vqs)(struct udevice *vdev);
+	/**
+	 * notify() - notify the device to process the queue
+	 *
+	 * @vdev:	the real virtio device
+	 * @vq:		virtqueue to process
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*notify)(struct udevice *vdev, struct virtqueue *vq);
+};
+
+/* Get access to a virtio bus' operations */
+#define virtio_get_ops(dev)	((struct dm_virtio_ops *)(dev)->driver->ops)
+
+/**
+ * virtio uclass per device private data
+ *
+ * @vqs:			virtualqueue for the virtio device
+ * @vdev:			the real virtio device underneath
+ * @legacy:			is it a legacy device?
+ * @device:			virtio device ID
+ * @vendor:			virtio vendor ID
+ * @features:			negotiated supported features
+ * @feature_table:		an array of feature supported by the driver
+ * @feature_table_size:		number of entries in the feature table array
+ * @feature_table_legacy:	same as feature_table but working in legacy mode
+ * @feature_table_size_legacy:	number of entries in feature table legacy array
+ */
+struct virtio_dev_priv {
+	struct list_head vqs;
+	struct udevice *vdev;
+	bool legacy;
+	u32 device;
+	u32 vendor;
+	u64 features;
+	const u32 *feature_table;
+	u32 feature_table_size;
+	const u32 *feature_table_legacy;
+	u32 feature_table_size_legacy;
+};
+
+/**
+ * virtio_get_config() - read the value of a configuration field
+ *
+ * @vdev:	the real virtio device
+ * @offset:	the offset of the configuration field
+ * @buf:	the buffer to write the field value into
+ * @len:	the length of the buffer
+ * @return 0 if OK, -ve on error
+ */
+int virtio_get_config(struct udevice *vdev, unsigned int offset,
+		      void *buf, unsigned int len);
+
+/**
+ * virtio_set_config() - write the value of a configuration field
+ *
+ * @vdev:	the real virtio device
+ * @offset:	the offset of the configuration field
+ * @buf:	the buffer to read the field value from
+ * @len:	the length of the buffer
+ * @return 0 if OK, -ve on error
+ */
+int virtio_set_config(struct udevice *vdev, unsigned int offset,
+		      void *buf, unsigned int len);
+
+/**
+ * virtio_generation() - config generation counter
+ *
+ * @vdev:	the real virtio device
+ * @counter:	the returned config generation counter
+ * @return 0 if OK, -ve on error
+ */
+int virtio_generation(struct udevice *vdev, u32 *counter);
+
+/**
+ * virtio_get_status() - read the status byte
+ *
+ * @vdev:	the real virtio device
+ * @status:	the returned status byte
+ * @return 0 if OK, -ve on error
+ */
+int virtio_get_status(struct udevice *vdev, u8 *status);
+
+/**
+ * virtio_set_status() - write the status byte
+ *
+ * @vdev:	the real virtio device
+ * @status:	the new status byte
+ * @return 0 if OK, -ve on error
+ */
+int virtio_set_status(struct udevice *vdev, u8 status);
+
+/**
+ * virtio_reset() - reset the device
+ *
+ * @vdev:	the real virtio device
+ * @return 0 if OK, -ve on error
+ */
+int virtio_reset(struct udevice *vdev);
+
+/**
+ * virtio_get_features() - get the array of feature bits for this device
+ *
+ * @vdev:	the real virtio device
+ * @features:	the first 32 feature bits (all we currently need)
+ * @return 0 if OK, -ve on error
+ */
+int virtio_get_features(struct udevice *vdev, u64 *features);
+
+/**
+ * virtio_set_features() - confirm what device features we'll be using
+ *
+ * @vdev:	the real virtio device
+ * @return 0 if OK, -ve on error
+ */
+int virtio_set_features(struct udevice *vdev);
+
+/**
+ * virtio_find_vqs() - find virtqueues and instantiate them
+ *
+ * @vdev:	the real virtio device
+ * @nvqs:	the number of virtqueues to find
+ * @vqs:	on success, includes new virtqueues
+ * @return 0 if OK, -ve on error
+ */
+int virtio_find_vqs(struct udevice *vdev, unsigned int nvqs,
+		    struct virtqueue *vqs[]);
+
+/**
+ * virtio_del_vqs() - free virtqueues found by find_vqs()
+ *
+ * @vdev:	the real virtio device
+ * @return 0 if OK, -ve on error
+ */
+int virtio_del_vqs(struct udevice *vdev);
+
+/**
+ * virtio_notify() - notify the device to process the queue
+ *
+ * @vdev:	the real virtio device
+ * @vq:		virtqueue to process
+ * @return 0 if OK, -ve on error
+ */
+int virtio_notify(struct udevice *vdev, struct virtqueue *vq);
+
+/**
+ * virtio_add_status() - helper to set a new status code to the device
+ *
+ * @vdev:	the real virtio device
+ * @status:	new status code to be added
+ */
+void virtio_add_status(struct udevice *vdev, u8 status);
+
+/**
+ * virtio_finalize_features() - helper to finalize features
+ *
+ * @vdev:	the real virtio device
+ * @return 0 if OK, -ve on error
+ */
+int virtio_finalize_features(struct udevice *vdev);
+
+/**
+ * virtio_driver_features_init() - initialize driver supported features
+ *
+ * This fills in the virtio device parent per child private data with the given
+ * information, which contains driver supported features and legacy features.
+ *
+ * This API should be called in the virtio device driver's bind method, so that
+ * later virtio transport uclass driver can utilize the driver supplied features
+ * to negotiate with the device on the final supported features.
+ *
+ * @priv:		virtio uclass per device private data
+ * @feature:		an array of feature supported by the driver
+ * @feature_size:	number of entries in the feature table array
+ * @feature_legacy:	same as feature_table but working in legacy mode
+ * @feature_legacy_size:number of entries in feature table legacy array
+ */
+void virtio_driver_features_init(struct virtio_dev_priv *priv,
+				 const u32 *feature,
+				 u32 feature_size,
+				 const u32 *feature_legacy,
+				 u32 feature_legacy_size);
+
+/**
+ * virtio_init() - helper to enumerate all known virtio devices
+ *
+ * @return 0 if OK, -ve on error
+ */
+int virtio_init(void);
+
+static inline u16 __virtio16_to_cpu(bool little_endian, __virtio16 val)
+{
+	if (little_endian)
+		return le16_to_cpu((__force __le16)val);
+	else
+		return be16_to_cpu((__force __be16)val);
+}
+
+static inline __virtio16 __cpu_to_virtio16(bool little_endian, u16 val)
+{
+	if (little_endian)
+		return (__force __virtio16)cpu_to_le16(val);
+	else
+		return (__force __virtio16)cpu_to_be16(val);
+}
+
+static inline u32 __virtio32_to_cpu(bool little_endian, __virtio32 val)
+{
+	if (little_endian)
+		return le32_to_cpu((__force __le32)val);
+	else
+		return be32_to_cpu((__force __be32)val);
+}
+
+static inline __virtio32 __cpu_to_virtio32(bool little_endian, u32 val)
+{
+	if (little_endian)
+		return (__force __virtio32)cpu_to_le32(val);
+	else
+		return (__force __virtio32)cpu_to_be32(val);
+}
+
+static inline u64 __virtio64_to_cpu(bool little_endian, __virtio64 val)
+{
+	if (little_endian)
+		return le64_to_cpu((__force __le64)val);
+	else
+		return be64_to_cpu((__force __be64)val);
+}
+
+static inline __virtio64 __cpu_to_virtio64(bool little_endian, u64 val)
+{
+	if (little_endian)
+		return (__force __virtio64)cpu_to_le64(val);
+	else
+		return (__force __virtio64)cpu_to_be64(val);
+}
+
+/**
+ * __virtio_test_bit - helper to test feature bits
+ *
+ * For use by transports. Devices should normally use virtio_has_feature,
+ * which includes more checks.
+ *
+ * @udev: the transport device
+ * @fbit: the feature bit
+ */
+static inline bool __virtio_test_bit(struct udevice *udev, unsigned int fbit)
+{
+	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+
+	/* Did you forget to fix assumptions on max features? */
+	if (__builtin_constant_p(fbit))
+		BUILD_BUG_ON(fbit >= 64);
+	else
+		WARN_ON(fbit >= 64);
+
+	return uc_priv->features & BIT_ULL(fbit);
+}
+
+/**
+ * __virtio_set_bit - helper to set feature bits
+ *
+ * For use by transports.
+ *
+ * @udev: the transport device
+ * @fbit: the feature bit
+ */
+static inline void __virtio_set_bit(struct udevice *udev, unsigned int fbit)
+{
+	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+
+	/* Did you forget to fix assumptions on max features? */
+	if (__builtin_constant_p(fbit))
+		BUILD_BUG_ON(fbit >= 64);
+	else
+		WARN_ON(fbit >= 64);
+
+	uc_priv->features |= BIT_ULL(fbit);
+}
+
+/**
+ * __virtio_clear_bit - helper to clear feature bits
+ *
+ * For use by transports.
+ *
+ * @vdev: the transport device
+ * @fbit: the feature bit
+ */
+static inline void __virtio_clear_bit(struct udevice *udev, unsigned int fbit)
+{
+	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+
+	/* Did you forget to fix assumptions on max features? */
+	if (__builtin_constant_p(fbit))
+		BUILD_BUG_ON(fbit >= 64);
+	else
+		WARN_ON(fbit >= 64);
+
+	uc_priv->features &= ~BIT_ULL(fbit);
+}
+
+/**
+ * virtio_has_feature - helper to determine if this device has this feature
+ *
+ * Note this API is only usable after the virtio device driver's bind phase,
+ * as the feature has been negotiated between the device and the driver.
+ *
+ * @vdev: the virtio device
+ * @fbit: the feature bit
+ */
+static inline bool virtio_has_feature(struct udevice *vdev, unsigned int fbit)
+{
+	if (!(vdev->flags & DM_FLAG_BOUND))
+		WARN_ON(true);
+
+	return __virtio_test_bit(vdev->parent, fbit);
+}
+
+static inline bool virtio_legacy_is_little_endian(void)
+{
+#ifdef __LITTLE_ENDIAN
+	return true;
+#else
+	return false;
+#endif
+}
+
+static inline bool virtio_is_little_endian(struct udevice *vdev)
+{
+	struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(vdev->parent);
+
+	return !uc_priv->legacy || virtio_legacy_is_little_endian();
+}
+
+/* Memory accessors */
+static inline u16 virtio16_to_cpu(struct udevice *vdev, __virtio16 val)
+{
+	return __virtio16_to_cpu(virtio_is_little_endian(vdev), val);
+}
+
+static inline __virtio16 cpu_to_virtio16(struct udevice *vdev, u16 val)
+{
+	return __cpu_to_virtio16(virtio_is_little_endian(vdev), val);
+}
+
+static inline u32 virtio32_to_cpu(struct udevice *vdev, __virtio32 val)
+{
+	return __virtio32_to_cpu(virtio_is_little_endian(vdev), val);
+}
+
+static inline __virtio32 cpu_to_virtio32(struct udevice *vdev, u32 val)
+{
+	return __cpu_to_virtio32(virtio_is_little_endian(vdev), val);
+}
+
+static inline u64 virtio64_to_cpu(struct udevice *vdev, __virtio64 val)
+{
+	return __virtio64_to_cpu(virtio_is_little_endian(vdev), val);
+}
+
+static inline __virtio64 cpu_to_virtio64(struct udevice *vdev, u64 val)
+{
+	return __cpu_to_virtio64(virtio_is_little_endian(vdev), val);
+}
+
+/* Read @count fields, @bytes each */
+static inline void __virtio_cread_many(struct udevice *vdev,
+				       unsigned int offset,
+				       void *buf, size_t count, size_t bytes)
+{
+	u32 old, gen;
+	int i;
+
+	/* no need to check return value as generation can be optional */
+	virtio_generation(vdev, &gen);
+	do {
+		old = gen;
+
+		for (i = 0; i < count; i++)
+			virtio_get_config(vdev, offset + bytes * i,
+					  buf + i * bytes, bytes);
+
+		virtio_generation(vdev, &gen);
+	} while (gen != old);
+}
+
+static inline void virtio_cread_bytes(struct udevice *vdev,
+				      unsigned int offset,
+				      void *buf, size_t len)
+{
+	__virtio_cread_many(vdev, offset, buf, len, 1);
+}
+
+static inline u8 virtio_cread8(struct udevice *vdev, unsigned int offset)
+{
+	u8 ret;
+
+	virtio_get_config(vdev, offset, &ret, sizeof(ret));
+	return ret;
+}
+
+static inline void virtio_cwrite8(struct udevice *vdev,
+				  unsigned int offset, u8 val)
+{
+	virtio_set_config(vdev, offset, &val, sizeof(val));
+}
+
+static inline u16 virtio_cread16(struct udevice *vdev,
+				 unsigned int offset)
+{
+	u16 ret;
+
+	virtio_get_config(vdev, offset, &ret, sizeof(ret));
+	return virtio16_to_cpu(vdev, (__force __virtio16)ret);
+}
+
+static inline void virtio_cwrite16(struct udevice *vdev,
+				   unsigned int offset, u16 val)
+{
+	val = (__force u16)cpu_to_virtio16(vdev, val);
+	virtio_set_config(vdev, offset, &val, sizeof(val));
+}
+
+static inline u32 virtio_cread32(struct udevice *vdev,
+				 unsigned int offset)
+{
+	u32 ret;
+
+	virtio_get_config(vdev, offset, &ret, sizeof(ret));
+	return virtio32_to_cpu(vdev, (__force __virtio32)ret);
+}
+
+static inline void virtio_cwrite32(struct udevice *vdev,
+				   unsigned int offset, u32 val)
+{
+	val = (__force u32)cpu_to_virtio32(vdev, val);
+	virtio_set_config(vdev, offset, &val, sizeof(val));
+}
+
+static inline u64 virtio_cread64(struct udevice *vdev,
+				 unsigned int offset)
+{
+	u64 ret;
+
+	__virtio_cread_many(vdev, offset, &ret, 1, sizeof(ret));
+	return virtio64_to_cpu(vdev, (__force __virtio64)ret);
+}
+
+static inline void virtio_cwrite64(struct udevice *vdev,
+				   unsigned int offset, u64 val)
+{
+	val = (__force u64)cpu_to_virtio64(vdev, val);
+	virtio_set_config(vdev, offset, &val, sizeof(val));
+}
+
+/* Config space read accessor */
+#define virtio_cread(vdev, structname, member, ptr)			\
+	do {								\
+		/* Must match the member's type, and be integer */	\
+		if (!typecheck(typeof((((structname *)0)->member)), *(ptr))) \
+			(*ptr) = 1;					\
+									\
+		switch (sizeof(*ptr)) {					\
+		case 1:							\
+			*(ptr) = virtio_cread8(vdev,			\
+					       offsetof(structname, member)); \
+			break;						\
+		case 2:							\
+			*(ptr) = virtio_cread16(vdev,			\
+						offsetof(structname, member)); \
+			break;						\
+		case 4:							\
+			*(ptr) = virtio_cread32(vdev,			\
+						offsetof(structname, member)); \
+			break;						\
+		case 8:							\
+			*(ptr) = virtio_cread64(vdev,			\
+						offsetof(structname, member)); \
+			break;						\
+		default:						\
+			WARN_ON(true);					\
+		}							\
+	} while (0)
+
+/* Config space write accessor */
+#define virtio_cwrite(vdev, structname, member, ptr)			\
+	do {								\
+		/* Must match the member's type, and be integer */	\
+		if (!typecheck(typeof((((structname *)0)->member)), *(ptr))) \
+			WARN_ON((*ptr) == 1);				\
+									\
+		switch (sizeof(*ptr)) {					\
+		case 1:							\
+			virtio_cwrite8(vdev,				\
+				       offsetof(structname, member),	\
+				       *(ptr));				\
+			break;						\
+		case 2:							\
+			virtio_cwrite16(vdev,				\
+					offsetof(structname, member),	\
+					*(ptr));			\
+			break;						\
+		case 4:							\
+			virtio_cwrite32(vdev,				\
+					offsetof(structname, member),	\
+					*(ptr));			\
+			break;						\
+		case 8:							\
+			virtio_cwrite64(vdev,				\
+					offsetof(structname, member),	\
+					*(ptr));			\
+			break;						\
+		default:						\
+			WARN_ON(true);					\
+		}							\
+	} while (0)
+
+/* Conditional config space accessors */
+#define virtio_cread_feature(vdev, fbit, structname, member, ptr)	\
+	({								\
+		int _r = 0;						\
+		if (!virtio_has_feature(vdev, fbit))			\
+			_r = -ENOENT;					\
+		else							\
+			virtio_cread(vdev, structname, member, ptr);	\
+		_r;							\
+	})
+
+#endif /* __VIRTIO_H__ */

include/virtio_types.h

@@ -0,0 +1,24 @@
+/* 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_types.h
+ */
+
+#ifndef _LINUX_VIRTIO_TYPES_H
+#define _LINUX_VIRTIO_TYPES_H
+
+#include <linux/types.h>
+
+/*
+ * __virtio{16,32,64} have the following meaning:
+ * - __u{16,32,64} for virtio devices in legacy mode, accessed in native endian
+ * - __le{16,32,64} for standard-compliant virtio devices
+ */
+
+typedef __u16 __bitwise __virtio16;
+typedef __u32 __bitwise __virtio32;
+typedef __u64 __bitwise __virtio64;
+
+#endif /* _LINUX_VIRTIO_TYPES_H */