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>

1 files changed, 129 insertions, 0 deletions

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 */