[PATCH v5 11/19] add minimal virtio support for devtree virtio-mmio

Andrew Jones
2014-06-11T14:01:55Z

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>
---
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 | 165 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
lib/virtio.h | 89 +++++++++++++++++++++++++++++++
3 files changed, 257 insertions(+)
create mode 100644 lib/virtio.c
create mode 100644 lib/virtio.h

diff --git a/lib/libcflat.h b/lib/libcflat.h
index 8886885766ddc..5939cee54890b 100644
--- a/lib/libcflat.h
+++ b/lib/libcflat.h
@@ -65,6 +65,9 @@ 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..4c597e27f4aff
--- /dev/null
+++ b/lib/virtio.c
@@ -0,0 +1,165 @@
+/*
+ * 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 "devicetree.h"
+#include "asm/spinlock.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 *vmdev = to_virtio_mmio_device(vdev);
+ u8 *p = buf;
+ unsigned i;
+
+ for (i = 0; i < len; ++i)
+ p[i] = readb(vmdev->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 *vmdev = to_virtio_mmio_device(vdev);
+ const u8 *p = buf;
+ unsigned i;
+
+ for (i = 0; i < len; ++i)
+ writeb(p[i], vmdev->base + VIRTIO_MMIO_CONFIG + offset + i);
+}
+
+static const struct virtio_config_ops vm_config_ops = {
+ .get = vm_get,
+ .set = vm_set,
+};
+
+#define NR_VM_DEVICES 32
+static struct spinlock vm_lock;
+static struct virtio_mmio_device vm_devs[NR_VM_DEVICES];
+static int nr_vm_devs;
+
+static struct virtio_mmio_device *vm_new_device(u32 devid)
+{
+ struct virtio_mmio_device *vmdev;
+
+ if (nr_vm_devs >= NR_VM_DEVICES)
+ return NULL;
+
+ spin_lock(&vm_lock);
+ vmdev = &vm_devs[nr_vm_devs++];
+ spin_unlock(&vm_lock);
+
+ vmdev->vdev.id.device = devid;
+ vmdev->vdev.id.vendor = -1;
+ vmdev->vdev.config = &vm_config_ops;
+
+ return vmdev;
+}
+
+/******************************************************
+ * 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;
+
+ dt_device_bind_node((struct dt_device *)dev, fdtnode);
+
+ assert(dt_pbus_get_base(dev, &base) == 0);
+ info->base = ioremap(base.addr, base.size);
+
+ return readl(info->base + VIRTIO_MMIO_DEVICE_ID) == info->devid;
+}
+
+static struct virtio_device *vm_dt_device_bind(u32 devid)
+{
+ struct virtio_mmio_device *vmdev;
+ 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;
+
+ vmdev = vm_new_device(devid);
+ vmdev->base = info.base;
+
+ return &vmdev->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