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>

5 files changed, 403 insertions, 0 deletions

diff --git a/drivers/Kconfig b/drivers/Kconfig
index 927a2b8..4ac823d 100644
--- a/drivers/Kconfig
+++ b/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"
diff --git a/drivers/Makefile b/drivers/Makefile
index fb38b67..4453c62 100644
--- a/drivers/Makefile
+++ b/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/
 
diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
new file mode 100644
index 0000000..82fc536
--- /dev/null
+++ b/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
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
new file mode 100644
index 0000000..23e7be7
--- /dev/null
+++ b/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
diff --git a/drivers/virtio/virtio-uclass.c b/drivers/virtio/virtio-uclass.c
new file mode 100644
index 0000000..34397d7
--- /dev/null
+++ b/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),
+};