virtio: Add virtio over mmio transport driver

VirtIO can use various different buses and virtio devices are
commonly implemented as PCI devices. But virtual environments
without PCI support (a common situation in embedded devices
models) might use simple memory mapped device (“virtio-mmio”)
instead of the PCI device.

This adds a transport driver that implements UCLASS_VIRTIO for
virtio over mmio.

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>

4 files changed, 550 insertions, 0 deletions

diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig
index 82fc536831..4f9a11b6ef 100644
--- a/drivers/virtio/Kconfig
+++ b/drivers/virtio/Kconfig
@@ -22,4 +22,11 @@ config VIRTIO
           This option is selected by any driver which implements the virtio
           transport, such as CONFIG_VIRTIO_MMIO or CONFIG_VIRTIO_PCI.
 
+config VIRTIO_MMIO
+        bool "Platform bus driver for memory mapped virtio devices"
+        select VIRTIO
+        help
+          This driver provides support for memory mapped virtio
+          platform device driver.
+
 endmenu
diff --git a/drivers/virtio/Makefile b/drivers/virtio/Makefile
index 17d264a771..2e487854a2 100644
--- a/drivers/virtio/Makefile
+++ b/drivers/virtio/Makefile
@@ -4,3 +4,4 @@
 # Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
 
 obj-y += virtio-uclass.o virtio_ring.o
+obj-$(CONFIG_VIRTIO_MMIO) += virtio_mmio.o
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
new file mode 100644
index 0000000000..7b738703b8
--- /dev/null
+++ b/drivers/virtio/virtio_mmio.c
@@ -0,0 +1,413 @@
+// 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 memory-maped I/O transport driver
+ * Ported from Linux drivers/virtio/virtio_mmio.c
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <virtio_types.h>
+#include <virtio.h>
+#include <virtio_ring.h>
+#include <linux/compat.h>
+#include <linux/io.h>
+#include "virtio_mmio.h"
+
+static int virtio_mmio_get_config(struct udevice *udev, unsigned int offset,
+                                  void *buf, unsigned int len)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+        void __iomem *base = priv->base + VIRTIO_MMIO_CONFIG;
+        u8 b;
+        __le16 w;
+        __le32 l;
+
+        if (priv->version == 1) {
+                u8 *ptr = buf;
+                int i;
+
+                for (i = 0; i < len; i++)
+                        ptr[i] = readb(base + offset + i);
+
+                return 0;
+        }
+
+        switch (len) {
+        case 1:
+                b = readb(base + offset);
+                memcpy(buf, &b, sizeof(b));
+                break;
+        case 2:
+                w = cpu_to_le16(readw(base + offset));
+                memcpy(buf, &w, sizeof(w));
+                break;
+        case 4:
+                l = cpu_to_le32(readl(base + offset));
+                memcpy(buf, &l, sizeof(l));
+                break;
+        case 8:
+                l = cpu_to_le32(readl(base + offset));
+                memcpy(buf, &l, sizeof(l));
+                l = cpu_to_le32(readl(base + offset + sizeof(l)));
+                memcpy(buf + sizeof(l), &l, sizeof(l));
+                break;
+        default:
+                WARN_ON(true);
+        }
+
+        return 0;
+}
+
+static int virtio_mmio_set_config(struct udevice *udev, unsigned int offset,
+                                  const void *buf, unsigned int len)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+        void __iomem *base = priv->base + VIRTIO_MMIO_CONFIG;
+        u8 b;
+        __le16 w;
+        __le32 l;
+
+        if (priv->version == 1) {
+                const u8 *ptr = buf;
+                int i;
+
+                for (i = 0; i < len; i++)
+                        writeb(ptr[i], base + offset + i);
+
+                return 0;
+        }
+
+        switch (len) {
+        case 1:
+                memcpy(&b, buf, sizeof(b));
+                writeb(b, base + offset);
+                break;
+        case 2:
+                memcpy(&w, buf, sizeof(w));
+                writew(le16_to_cpu(w), base + offset);
+                break;
+        case 4:
+                memcpy(&l, buf, sizeof(l));
+                writel(le32_to_cpu(l), base + offset);
+                break;
+        case 8:
+                memcpy(&l, buf, sizeof(l));
+                writel(le32_to_cpu(l), base + offset);
+                memcpy(&l, buf + sizeof(l), sizeof(l));
+                writel(le32_to_cpu(l), base + offset + sizeof(l));
+                break;
+        default:
+                WARN_ON(true);
+        }
+
+        return 0;
+}
+
+static int virtio_mmio_generation(struct udevice *udev, u32 *counter)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+
+        if (priv->version == 1)
+                *counter = 0;
+        else
+                *counter = readl(priv->base + VIRTIO_MMIO_CONFIG_GENERATION);
+
+        return 0;
+}
+
+static int virtio_mmio_get_status(struct udevice *udev, u8 *status)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+
+        *status = readl(priv->base + VIRTIO_MMIO_STATUS) & 0xff;
+
+        return 0;
+}
+
+static int virtio_mmio_set_status(struct udevice *udev, u8 status)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+
+        /* We should never be setting status to 0 */
+        WARN_ON(status == 0);
+
+        writel(status, priv->base + VIRTIO_MMIO_STATUS);
+
+        return 0;
+}
+
+static int virtio_mmio_reset(struct udevice *udev)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+
+        /* 0 status means a reset */
+        writel(0, priv->base + VIRTIO_MMIO_STATUS);
+
+        return 0;
+}
+
+static int virtio_mmio_get_features(struct udevice *udev, u64 *features)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+
+        writel(1, priv->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
+        *features = readl(priv->base + VIRTIO_MMIO_DEVICE_FEATURES);
+        *features <<= 32;
+
+        writel(0, priv->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
+        *features |= readl(priv->base + VIRTIO_MMIO_DEVICE_FEATURES);
+
+        return 0;
+}
+
+static int virtio_mmio_set_features(struct udevice *udev)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+
+        /* Make sure there is are no mixed devices */
+        if (priv->version == 2 && uc_priv->legacy) {
+                debug("New virtio-mmio devices (version 2) must provide VIRTIO_F_VERSION_1 feature!\n");
+                return -EINVAL;
+        }
+
+        writel(1, priv->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
+        writel((u32)(uc_priv->features >> 32),
+               priv->base + VIRTIO_MMIO_DRIVER_FEATURES);
+
+        writel(0, priv->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
+        writel((u32)uc_priv->features,
+               priv->base + VIRTIO_MMIO_DRIVER_FEATURES);
+
+        return 0;
+}
+
+static struct virtqueue *virtio_mmio_setup_vq(struct udevice *udev,
+                                              unsigned int index)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+        struct virtqueue *vq;
+        unsigned int num;
+        int err;
+
+        /* Select the queue we're interested in */
+        writel(index, priv->base + VIRTIO_MMIO_QUEUE_SEL);
+
+        /* Queue shouldn't already be set up */
+        if (readl(priv->base + (priv->version == 1 ?
+            VIRTIO_MMIO_QUEUE_PFN : VIRTIO_MMIO_QUEUE_READY))) {
+                err = -ENOENT;
+                goto error_available;
+        }
+
+        num = readl(priv->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
+        if (num == 0) {
+                err = -ENOENT;
+                goto error_new_virtqueue;
+        }
+
+        /* Create the vring */
+        vq = vring_create_virtqueue(index, num, VIRTIO_MMIO_VRING_ALIGN, udev);
+        if (!vq) {
+                err = -ENOMEM;
+                goto error_new_virtqueue;
+        }
+
+        /* Activate the queue */
+        writel(virtqueue_get_vring_size(vq),
+               priv->base + VIRTIO_MMIO_QUEUE_NUM);
+        if (priv->version == 1) {
+                u64 q_pfn = virtqueue_get_desc_addr(vq) >> PAGE_SHIFT;
+
+                /*
+                 * virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something
+                 * that doesn't fit in 32bit, fail the setup rather than
+                 * pretending to be successful.
+                 */
+                if (q_pfn >> 32) {
+                        debug("platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
+                              0x1ULL << (32 + PAGE_SHIFT - 30));
+                        err = -E2BIG;
+                        goto error_bad_pfn;
+                }
+
+                writel(PAGE_SIZE, priv->base + VIRTIO_MMIO_QUEUE_ALIGN);
+                writel(q_pfn, priv->base + VIRTIO_MMIO_QUEUE_PFN);
+        } else {
+                u64 addr;
+
+                addr = virtqueue_get_desc_addr(vq);
+                writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
+                writel((u32)(addr >> 32),
+                       priv->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
+
+                addr = virtqueue_get_avail_addr(vq);
+                writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
+                writel((u32)(addr >> 32),
+                       priv->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
+
+                addr = virtqueue_get_used_addr(vq);
+                writel((u32)addr, priv->base + VIRTIO_MMIO_QUEUE_USED_LOW);
+                writel((u32)(addr >> 32),
+                       priv->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
+
+                writel(1, priv->base + VIRTIO_MMIO_QUEUE_READY);
+        }
+
+        return vq;
+
+error_bad_pfn:
+        vring_del_virtqueue(vq);
+
+error_new_virtqueue:
+        if (priv->version == 1) {
+                writel(0, priv->base + VIRTIO_MMIO_QUEUE_PFN);
+        } else {
+                writel(0, priv->base + VIRTIO_MMIO_QUEUE_READY);
+                WARN_ON(readl(priv->base + VIRTIO_MMIO_QUEUE_READY));
+        }
+
+error_available:
+        return ERR_PTR(err);
+}
+
+static void virtio_mmio_del_vq(struct virtqueue *vq)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(vq->vdev);
+        unsigned int index = vq->index;
+
+        /* Select and deactivate the queue */
+        writel(index, priv->base + VIRTIO_MMIO_QUEUE_SEL);
+        if (priv->version == 1) {
+                writel(0, priv->base + VIRTIO_MMIO_QUEUE_PFN);
+        } else {
+                writel(0, priv->base + VIRTIO_MMIO_QUEUE_READY);
+                WARN_ON(readl(priv->base + VIRTIO_MMIO_QUEUE_READY));
+        }
+
+        vring_del_virtqueue(vq);
+}
+
+static int virtio_mmio_del_vqs(struct udevice *udev)
+{
+        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+        struct virtqueue *vq, *n;
+
+        list_for_each_entry_safe(vq, n, &uc_priv->vqs, list)
+                virtio_mmio_del_vq(vq);
+
+        return 0;
+}
+
+static int virtio_mmio_find_vqs(struct udevice *udev, unsigned int nvqs,
+                                struct virtqueue *vqs[])
+{
+        int i;
+
+        for (i = 0; i < nvqs; ++i) {
+                vqs[i] = virtio_mmio_setup_vq(udev, i);
+                if (IS_ERR(vqs[i])) {
+                        virtio_mmio_del_vqs(udev);
+                        return PTR_ERR(vqs[i]);
+                }
+        }
+
+        return 0;
+}
+
+static int virtio_mmio_notify(struct udevice *udev, struct virtqueue *vq)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+
+        /*
+         * We write the queue's selector into the notification register
+         * to signal the other end
+         */
+        writel(vq->index, priv->base + VIRTIO_MMIO_QUEUE_NOTIFY);
+
+        return 0;
+}
+
+static int virtio_mmio_ofdata_to_platdata(struct udevice *udev)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+
+        priv->base = (void __iomem *)(ulong)dev_read_addr(udev);
+        if (priv->base == (void __iomem *)FDT_ADDR_T_NONE)
+                return -EINVAL;
+
+        return 0;
+}
+
+static int virtio_mmio_probe(struct udevice *udev)
+{
+        struct virtio_mmio_priv *priv = dev_get_priv(udev);
+        struct virtio_dev_priv *uc_priv = dev_get_uclass_priv(udev);
+        u32 magic;
+
+        /* Check magic value */
+        magic = readl(priv->base + VIRTIO_MMIO_MAGIC_VALUE);
+        if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
+                debug("(%s): wrong magic value 0x%08x!\n", udev->name, magic);
+                return 0;
+        }
+
+        /* Check device version */
+        priv->version = readl(priv->base + VIRTIO_MMIO_VERSION);
+        if (priv->version < 1 || priv->version > 2) {
+                debug("(%s): version %d not supported!\n",
+                      udev->name, priv->version);
+                return 0;
+        }
+
+        /* Check devicd ID */
+        uc_priv->device = readl(priv->base + VIRTIO_MMIO_DEVICE_ID);
+        if (uc_priv->device == 0) {
+                /*
+                 * virtio-mmio device with an ID 0 is a (dummy) placeholder
+                 * with no function. End probing now with no error reported.
+                 */
+                return 0;
+        }
+        uc_priv->vendor = readl(priv->base + VIRTIO_MMIO_VENDOR_ID);
+
+        if (priv->version == 1)
+                writel(PAGE_SIZE, priv->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
+
+        debug("(%s): device (%d) vendor (%08x) version (%d)\n", udev->name,
+              uc_priv->device, uc_priv->vendor, priv->version);
+
+        return 0;
+}
+
+static const struct dm_virtio_ops virtio_mmio_ops = {
+        .get_config     = virtio_mmio_get_config,
+        .set_config     = virtio_mmio_set_config,
+        .generation     = virtio_mmio_generation,
+        .get_status     = virtio_mmio_get_status,
+        .set_status     = virtio_mmio_set_status,
+        .reset          = virtio_mmio_reset,
+        .get_features   = virtio_mmio_get_features,
+        .set_features   = virtio_mmio_set_features,
+        .find_vqs       = virtio_mmio_find_vqs,
+        .del_vqs        = virtio_mmio_del_vqs,
+        .notify         = virtio_mmio_notify,
+};
+
+static const struct udevice_id virtio_mmio_ids[] = {
+        { .compatible = "virtio,mmio" },
+        { }
+};
+
+U_BOOT_DRIVER(virtio_mmio) = {
+        .name   = "virtio-mmio",
+        .id     = UCLASS_VIRTIO,
+        .of_match = virtio_mmio_ids,
+        .ops    = &virtio_mmio_ops,
+        .probe  = virtio_mmio_probe,
+        .ofdata_to_platdata = virtio_mmio_ofdata_to_platdata,
+        .priv_auto_alloc_size = sizeof(struct virtio_mmio_priv),
+};
diff --git a/drivers/virtio/virtio_mmio.h b/drivers/virtio/virtio_mmio.h
new file mode 100644
index 0000000000..b3408828a5
--- /dev/null
+++ b/drivers/virtio/virtio_mmio.h
@@ -0,0 +1,129 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * 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_mmio.h
+ */
+
+#ifndef _LINUX_VIRTIO_MMIO_H
+#define _LINUX_VIRTIO_MMIO_H
+
+/* Control registers */
+
+/* Magic value ("virt" string) - Read Only */
+#define VIRTIO_MMIO_MAGIC_VALUE         0x000
+
+/* Virtio device version - Read Only */
+#define VIRTIO_MMIO_VERSION             0x004
+
+/* Virtio device ID - Read Only */
+#define VIRTIO_MMIO_DEVICE_ID           0x008
+
+/* Virtio vendor ID - Read Only */
+#define VIRTIO_MMIO_VENDOR_ID           0x00c
+
+/*
+ * Bitmask of the features supported by the device (host)
+ * (32 bits per set) - Read Only
+ */
+#define VIRTIO_MMIO_DEVICE_FEATURES     0x010
+
+/* Device (host) features set selector - Write Only */
+#define VIRTIO_MMIO_DEVICE_FEATURES_SEL 0x014
+
+/*
+ * Bitmask of features activated by the driver (guest)
+ * (32 bits per set) - Write Only
+ */
+#define VIRTIO_MMIO_DRIVER_FEATURES     0x020
+
+/* Activated features set selector - Write Only */
+#define VIRTIO_MMIO_DRIVER_FEATURES_SEL 0x024
+
+#ifndef VIRTIO_MMIO_NO_LEGACY /* LEGACY DEVICES ONLY! */
+
+/* Guest's memory page size in bytes - Write Only */
+#define VIRTIO_MMIO_GUEST_PAGE_SIZE     0x028
+
+#endif
+
+/* Queue selector - Write Only */
+#define VIRTIO_MMIO_QUEUE_SEL           0x030
+
+/* Maximum size of the currently selected queue - Read Only */
+#define VIRTIO_MMIO_QUEUE_NUM_MAX       0x034
+
+/* Queue size for the currently selected queue - Write Only */
+#define VIRTIO_MMIO_QUEUE_NUM           0x038
+
+#ifndef VIRTIO_MMIO_NO_LEGACY /* LEGACY DEVICES ONLY! */
+
+/* Used Ring alignment for the currently selected queue - Write Only */
+#define VIRTIO_MMIO_QUEUE_ALIGN         0x03c
+
+/* Guest's PFN for the currently selected queue - Read Write */
+#define VIRTIO_MMIO_QUEUE_PFN           0x040
+
+#endif
+
+/* Ready bit for the currently selected queue - Read Write */
+#define VIRTIO_MMIO_QUEUE_READY         0x044
+
+/* Queue notifier - Write Only */
+#define VIRTIO_MMIO_QUEUE_NOTIFY        0x050
+
+/* Interrupt status - Read Only */
+#define VIRTIO_MMIO_INTERRUPT_STATUS    0x060
+
+/* Interrupt acknowledge - Write Only */
+#define VIRTIO_MMIO_INTERRUPT_ACK       0x064
+
+/* Device status register - Read Write */
+#define VIRTIO_MMIO_STATUS              0x070
+
+/* Selected queue's Descriptor Table address, 64 bits in two halves */
+#define VIRTIO_MMIO_QUEUE_DESC_LOW      0x080
+#define VIRTIO_MMIO_QUEUE_DESC_HIGH     0x084
+
+/* Selected queue's Available Ring address, 64 bits in two halves */
+#define VIRTIO_MMIO_QUEUE_AVAIL_LOW     0x090
+#define VIRTIO_MMIO_QUEUE_AVAIL_HIGH    0x094
+
+/* Selected queue's Used Ring address, 64 bits in two halves */
+#define VIRTIO_MMIO_QUEUE_USED_LOW      0x0a0
+#define VIRTIO_MMIO_QUEUE_USED_HIGH     0x0a4
+
+/* Configuration atomicity value */
+#define VIRTIO_MMIO_CONFIG_GENERATION   0x0fc
+
+/*
+ * The config space is defined by each driver as
+ * the per-driver configuration space - Read Write
+ */
+#define VIRTIO_MMIO_CONFIG              0x100
+
+/* Interrupt flags (re: interrupt status & acknowledge registers) */
+
+#define VIRTIO_MMIO_INT_VRING           BIT(0)
+#define VIRTIO_MMIO_INT_CONFIG          BIT(1)
+
+/*
+ * The alignment to use between consumer and producer parts of vring.
+ * Currently hardcoded to the page size.
+ */
+#define PAGE_SHIFT                      12
+#define VIRTIO_MMIO_VRING_ALIGN         PAGE_SIZE
+
+/**
+ * virtio mmio transport driver private data
+ *
+ * @base:               mmio transport device register base
+ * @version:            mmio transport device version
+ */
+struct virtio_mmio_priv {
+        void __iomem *base;
+        u32 version;
+};
+
+#endif /* _LINUX_VIRTIO_MMIO_H */