[PATCH v6 07/17] add minimal virtio support for devtree virtio-mmio

[Andrew Jones <drjones@redhat.com>]

Support the bare minimum of virtio to enable access to the virtio-mmio
config space of a device. Currently this implementation must use a
device tree to find the device.

Signed-off-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
---
v6:
 - switch to using alloc()
 - s/vmdev/vm_dev/ to be consistent with kernel naming
 - check for virtio magic in vm_dt_match
v5:
 - use same virtio struct names as kernel
 - no need to alloc a new virtio_config_ops for each virtio device
 - use ioremap
v4:
 - split from the virtio-testdev patch
 - search a table to "discover" that the device must be DT/virtio-mmio,
   which doesn't change anything, but looks less hacky than comments
   saying the device must be DT/virtio-mmio...
 - manage own pool of virtio-mmio pre-allocated device structures in
   order to avoid needing access to the heap
---
 lib/libcflat.h |   3 ++
 lib/virtio.c   | 158 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/virtio.h   |  89 ++++++++++++++++++++++++++++++++
 3 files changed, 250 insertions(+)
 create mode 100644 lib/virtio.c
 create mode 100644 lib/virtio.h

diff --git a/lib/libcflat.h b/lib/libcflat.h
index 9f76d6741344d..57bdb92a3e1b4 100644
--- a/lib/libcflat.h
+++ b/lib/libcflat.h
@@ -56,6 +56,9 @@ extern long atol(const char *ptr);
 #define ARRAY_SIZE(_a)  (sizeof(_a)/sizeof((_a)[0]))
 
 #define offsetof(TYPE, MEMBER) __builtin_offsetof (TYPE, MEMBER)
+#define container_of(ptr, type, member) ({				\
+	const typeof( ((type *)0)->member ) *__mptr = (ptr);		\
+	(type *)( (char *)__mptr - offsetof(type,member) );})
 
 #define NULL ((void *)0UL)
 
diff --git a/lib/virtio.c b/lib/virtio.c
new file mode 100644
index 0000000000000..8e48d364bec7e
--- /dev/null
+++ b/lib/virtio.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright (C) 2014, Red Hat Inc, Andrew Jones <drjones@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.
+ */
+#include "libcflat.h"
+#include "alloc.h"
+#include "devicetree.h"
+#include "asm/io.h"
+#include "virtio.h"
+
+enum virtio_hwdesc_type {
+	VIRTIO_HWDESC_TYPE_DT = 0,	/* device tree */
+	NR_VIRTIO_HWDESC_TYPES,
+};
+
+enum virtio_bus_type {
+	VIRTIO_BUS_TYPE_MMIO = 0,	/* virtio-mmio */
+	NR_VIRTIO_BUS_TYPES,
+};
+
+struct virtio_bind_bus {
+	bool (*hwdesc_probe)(void);
+	struct virtio_device *(*device_bind)(u32 devid);
+};
+
+static struct virtio_device *vm_dt_device_bind(u32 devid);
+
+static struct virtio_bind_bus
+virtio_bind_busses[NR_VIRTIO_HWDESC_TYPES][NR_VIRTIO_BUS_TYPES] = {
+
+[VIRTIO_HWDESC_TYPE_DT] = {
+
+	[VIRTIO_BUS_TYPE_MMIO] = {
+		.hwdesc_probe = dt_available,
+		.device_bind = vm_dt_device_bind,
+	},
+},
+};
+
+struct virtio_device *virtio_bind(u32 devid)
+{
+	struct virtio_bind_bus *bus;
+	struct virtio_device *dev;
+	int i, j;
+
+	for (i = 0; i < NR_VIRTIO_HWDESC_TYPES; ++i) {
+		for (j = 0; j < NR_VIRTIO_BUS_TYPES; ++j) {
+
+			bus = &virtio_bind_busses[i][j];
+
+			if (!bus->hwdesc_probe())
+				continue;
+
+			dev = bus->device_bind(devid);
+			if (dev)
+				return dev;
+		}
+	}
+
+	return NULL;
+}
+
+/******************************************************
+ * virtio-mmio support (config space only)
+ ******************************************************/
+
+static void vm_get(struct virtio_device *vdev, unsigned offset,
+		   void *buf, unsigned len)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	u8 *p = buf;
+	unsigned i;
+
+	for (i = 0; i < len; ++i)
+		p[i] = readb(vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
+}
+
+static void vm_set(struct virtio_device *vdev, unsigned offset,
+		   const void *buf, unsigned len)
+{
+	struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
+	const u8 *p = buf;
+	unsigned i;
+
+	for (i = 0; i < len; ++i)
+		writeb(p[i], vm_dev->base + VIRTIO_MMIO_CONFIG + offset + i);
+}
+
+static const struct virtio_config_ops vm_config_ops = {
+	.get = vm_get,
+	.set = vm_set,
+};
+
+static void vm_device_init(struct virtio_mmio_device *vm_dev)
+{
+	vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
+	vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
+	vm_dev->vdev.config = &vm_config_ops;
+}
+
+/******************************************************
+ * virtio-mmio device tree support
+ ******************************************************/
+
+struct vm_dt_info {
+	u32 devid;
+	void *base;
+};
+
+static int vm_dt_match(const struct dt_device *dev, int fdtnode)
+{
+	struct vm_dt_info *info = (struct vm_dt_info *)dev->info;
+	struct dt_pbus_reg base;
+	u32 magic;
+
+	dt_device_bind_node((struct dt_device *)dev, fdtnode);
+
+	assert(dt_pbus_get_base(dev, &base) == 0);
+	info->base = ioremap(base.addr, base.size);
+
+	magic = readl(info->base + VIRTIO_MMIO_MAGIC_VALUE);
+	if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24))
+		return false;
+
+	return readl(info->base + VIRTIO_MMIO_DEVICE_ID) == info->devid;
+}
+
+static struct virtio_device *vm_dt_device_bind(u32 devid)
+{
+	struct virtio_mmio_device *vm_dev;
+	struct dt_device dt_dev;
+	struct dt_bus dt_bus;
+	struct vm_dt_info info;
+	int node;
+
+	dt_bus_init_defaults(&dt_bus);
+	dt_bus.match = vm_dt_match;
+
+	info.devid = devid;
+
+	dt_device_init(&dt_dev, &dt_bus, &info);
+
+	node = dt_device_find_compatible(&dt_dev, "virtio,mmio");
+	assert(node >= 0 || node == -FDT_ERR_NOTFOUND);
+
+	if (node == -FDT_ERR_NOTFOUND)
+		return NULL;
+
+	vm_dev = alloc(sizeof(*vm_dev));
+	if (!vm_dev)
+		return NULL;
+
+	vm_dev->base = info.base;
+	vm_device_init(vm_dev);
+
+	return &vm_dev->vdev;
+}
diff --git a/lib/virtio.h b/lib/virtio.h
new file mode 100644
index 0000000000000..16ebe7e0a7e70
--- /dev/null
+++ b/lib/virtio.h
@@ -0,0 +1,89 @@
+#ifndef _VIRTIO_H_
+#define _VIRTIO_H_
+/*
+ * A minimal implementation of virtio for virtio-mmio config space
+ * access.
+ *
+ * Copyright (C) 2014, Red Hat Inc, Andrew Jones <drjones@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU LGPL, version 2.
+ */
+#include "libcflat.h"
+
+struct virtio_device_id {
+	u32 device;
+	u32 vendor;
+};
+
+struct virtio_device {
+	struct virtio_device_id id;
+	const struct virtio_config_ops *config;
+};
+
+struct virtio_config_ops {
+	void (*get)(struct virtio_device *vdev, unsigned offset,
+		    void *buf, unsigned len);
+	void (*set)(struct virtio_device *vdev, unsigned offset,
+		    const void *buf, unsigned len);
+};
+
+extern struct virtio_device *virtio_bind(u32 devid);
+
+static inline u8
+virtio_config_readb(struct virtio_device *vdev, unsigned offset)
+{
+	u8 val;
+	vdev->config->get(vdev, offset, &val, 1);
+	return val;
+}
+
+static inline u16
+virtio_config_readw(struct virtio_device *vdev, unsigned offset)
+{
+	u16 val;
+	vdev->config->get(vdev, offset, &val, 2);
+	return val;
+}
+
+static inline u32
+virtio_config_readl(struct virtio_device *vdev, unsigned offset)
+{
+	u32 val;
+	vdev->config->get(vdev, offset, &val, 4);
+	return val;
+}
+
+static inline void
+virtio_config_writeb(struct virtio_device *vdev, unsigned offset, u8 val)
+{
+	vdev->config->set(vdev, offset, &val, 1);
+}
+
+static inline void
+virtio_config_writew(struct virtio_device *vdev, unsigned offset, u16 val)
+{
+	vdev->config->set(vdev, offset, &val, 2);
+}
+
+static inline void
+virtio_config_writel(struct virtio_device *vdev, unsigned offset, u32 val)
+{
+	vdev->config->set(vdev, offset, &val, 4);
+}
+
+/******************************************************
+ * virtio-mmio
+ ******************************************************/
+
+#define VIRTIO_MMIO_DEVICE_ID	0x008
+#define VIRTIO_MMIO_CONFIG	0x100
+
+#define to_virtio_mmio_device(vdev_ptr) \
+	container_of(vdev_ptr, struct virtio_mmio_device, vdev)
+
+struct virtio_mmio_device {
+	struct virtio_device vdev;
+	void *base;
+};
+
+#endif /* _VIRTIO_H_ */
-- 
1.9.3