[lib][bio] add simple block io layer
diff --git a/lib/bio/bio.c b/lib/bio/bio.c
new file mode 100644
index 0000000..3c35400
--- /dev/null
+++ b/lib/bio/bio.c
@@ -0,0 +1,445 @@
+/*
+ * Copyright (c) 2009 Travis Geiselbrecht
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include <stdlib.h>
+#include <debug.h>
+#include <err.h>
+#include <string.h>
+#include <list.h>
+#include <lib/bio.h>
+#include <kernel/mutex.h>
+
+#define LOCAL_TRACE 0
+
+struct bdev_struct {
+ struct list_node list;
+ mutex_t lock;
+};
+
+static struct bdev_struct *bdevs;
+
+/* default implementation is to use the read_block hook to 'deblock' the device */
+static ssize_t bio_default_read(struct bdev *dev, void *_buf, off_t offset, size_t len)
+{
+ uint8_t *buf = (uint8_t *)_buf;
+ ssize_t bytes_read = 0;
+ bnum_t block;
+ int err = 0;
+ STACKBUF_DMA_ALIGN(temp, dev->block_size); // temporary buffer for partial block transfers
+
+ /* find the starting block */
+ block = offset / dev->block_size;
+
+ LTRACEF("buf %p, offset %lld, block %u, len %zd\n", buf, offset, block, len);
+ /* handle partial first block */
+ if ((offset % dev->block_size) != 0) {
+ /* read in the block */
+ err = bio_read_block(dev, temp, block, 1);
+ if (err < 0)
+ goto err;
+
+ /* copy what we need */
+ size_t block_offset = offset % dev->block_size;
+ size_t tocopy = MIN(dev->block_size - block_offset, len);
+ memcpy(buf, temp + block_offset, tocopy);
+
+ /* increment our buffers */
+ buf += tocopy;
+ len -= tocopy;
+ bytes_read += tocopy;
+ block++;
+ }
+
+ LTRACEF("buf %p, block %u, len %zd\n", buf, block, len);
+ /* handle middle blocks */
+ if (len >= dev->block_size) {
+ /* do the middle reads */
+ size_t block_count = len / dev->block_size;
+ err = bio_read_block(dev, buf, block, block_count);
+ if (err < 0)
+ goto err;
+
+ /* increment our buffers */
+ size_t bytes = block_count * dev->block_size;
+ DEBUG_ASSERT(bytes <= len);
+
+ buf += bytes;
+ len -= bytes;
+ bytes_read += bytes;
+ block += block_count;
+ }
+
+ LTRACEF("buf %p, block %u, len %zd\n", buf, block, len);
+ /* handle partial last block */
+ if (len > 0) {
+ /* read the block */
+ err = bio_read_block(dev, temp, block, 1);
+ if (err < 0)
+ goto err;
+
+ /* copy the partial block from our temp buffer */
+ memcpy(buf, temp, len);
+
+ bytes_read += len;
+ }
+
+err:
+ /* return error or bytes read */
+ return (err >= 0) ? bytes_read : err;
+}
+
+static ssize_t bio_default_write(struct bdev *dev, const void *_buf, off_t offset, size_t len)
+{
+ const uint8_t *buf = (const uint8_t *)_buf;
+ ssize_t bytes_written = 0;
+ bnum_t block;
+ int err = 0;
+ STACKBUF_DMA_ALIGN(temp, dev->block_size); // temporary buffer for partial block transfers
+
+ /* find the starting block */
+ block = offset / dev->block_size;
+
+ LTRACEF("buf %p, offset %lld, block %u, len %zd\n", buf, offset, block, len);
+ /* handle partial first block */
+ if ((offset % dev->block_size) != 0) {
+ /* read in the block */
+ err = bio_read_block(dev, temp, block, 1);
+ if (err < 0)
+ goto err;
+
+ /* copy what we need */
+ size_t block_offset = offset % dev->block_size;
+ size_t tocopy = MIN(dev->block_size - block_offset, len);
+ memcpy(temp + block_offset, buf, tocopy);
+
+ /* write it back out */
+ err = bio_write_block(dev, temp, block, 1);
+ if (err < 0)
+ goto err;
+
+ /* increment our buffers */
+ buf += tocopy;
+ len -= tocopy;
+ bytes_written += tocopy;
+ block++;
+ }
+
+ LTRACEF("buf %p, block %u, len %zd\n", buf, block, len);
+ /* handle middle blocks */
+ if (len >= dev->block_size) {
+ /* do the middle writes */
+ size_t block_count = len / dev->block_size;
+ err = bio_write_block(dev, buf, block, block_count);
+ if (err < 0)
+ goto err;
+
+ /* increment our buffers */
+ size_t bytes = block_count * dev->block_size;
+ DEBUG_ASSERT(bytes <= len);
+
+ buf += bytes;
+ len -= bytes;
+ bytes_written += bytes;
+ block += block_count;
+ }
+
+ LTRACEF("buf %p, block %u, len %zd\n", buf, block, len);
+ /* handle partial last block */
+ if (len > 0) {
+ /* read the block */
+ err = bio_read_block(dev, temp, block, 1);
+ if (err < 0)
+ goto err;
+
+ /* copy the partial block from our temp buffer */
+ memcpy(temp, buf, len);
+
+ /* write it back out */
+ err = bio_write_block(dev, temp, block, 1);
+ if (err < 0)
+ goto err;
+
+ bytes_written += len;
+ }
+
+err:
+ /* return error or bytes written */
+ return (err >= 0) ? bytes_written : err;
+}
+
+static ssize_t bio_default_erase(struct bdev *dev, off_t offset, size_t len)
+{
+ /* default erase operation is to just write zeros over the device */
+#define ERASE_BUF_SIZE 4096
+ uint8_t *zero_buf;
+
+ zero_buf = calloc(1, ERASE_BUF_SIZE);
+
+ size_t remaining = len;
+ off_t pos = offset;
+ while (remaining > 0) {
+ ssize_t towrite = MIN(remaining, ERASE_BUF_SIZE);
+
+ ssize_t written = bio_write(dev, zero_buf, pos, towrite);
+ if (written < 0)
+ return pos;
+
+ pos += written;
+ remaining -= written;
+
+ if (written < towrite)
+ return pos;
+ }
+
+ return len;
+}
+
+static ssize_t bio_default_read_block(struct bdev *dev, void *buf, bnum_t block, uint count)
+{
+ panic("%s no reasonable default operation\n", __PRETTY_FUNCTION__);
+}
+
+static ssize_t bio_default_write_block(struct bdev *dev, const void *buf, bnum_t block, uint count)
+{
+ panic("%s no reasonable default operation\n", __PRETTY_FUNCTION__);
+}
+
+static void bdev_inc_ref(bdev_t *dev)
+{
+ atomic_add(&dev->ref, 1);
+}
+
+static void bdev_dec_ref(bdev_t *dev)
+{
+ int oldval = atomic_add(&dev->ref, -1);
+ if (oldval == 1) {
+ // last ref, remove it
+ DEBUG_ASSERT(!list_in_list(&dev->node));
+
+ TRACEF("last ref, removing (%s)\n", dev->name);
+
+ // call the close hook if it exists
+ if (dev->close)
+ dev->close(dev);
+
+ free(dev->name);
+ free(dev);
+ }
+}
+
+bdev_t *bio_open(const char *name)
+{
+ bdev_t *bdev = NULL;
+
+ /* see if it's in our list */
+ bdev_t *entry;
+ mutex_acquire(&bdevs->lock);
+ list_for_every_entry(&bdevs->list, entry, bdev_t, node) {
+ DEBUG_ASSERT(entry->ref > 0);
+ if (!strcmp(entry->name, name)) {
+ bdev = entry;
+ bdev_inc_ref(bdev);
+ break;
+ }
+ }
+ mutex_release(&bdevs->lock);
+
+ return bdev;
+}
+
+void bio_close(bdev_t *dev)
+{
+ DEBUG_ASSERT(dev);
+
+ bdev_dec_ref(dev);
+}
+
+ssize_t bio_read(bdev_t *dev, void *buf, off_t offset, size_t len)
+{
+ LTRACEF("dev '%s', buf %p, offset %lld, len %zd\n", dev->name, buf, offset, len);
+
+ DEBUG_ASSERT(dev->ref > 0);
+
+ /* range check */
+ if (offset < 0)
+ return -1;
+ if (offset >= dev->size)
+ return 0;
+ if (len == 0)
+ return 0;
+ if (offset + len > dev->size)
+ len = dev->size - offset;
+
+ return dev->read(dev, buf, offset, len);
+}
+
+ssize_t bio_read_block(bdev_t *dev, void *buf, bnum_t block, uint count)
+{
+ LTRACEF("dev '%s', buf %p, block %d, count %u\n", dev->name, buf, block, count);
+
+ DEBUG_ASSERT(dev->ref > 0);
+
+ /* range check */
+ if (block > dev->block_count)
+ return 0;
+ if (count == 0)
+ return 0;
+ if (block + count > dev->block_count)
+ count = dev->block_count - block;
+
+ return dev->read_block(dev, buf, block, count);
+}
+
+ssize_t bio_write(bdev_t *dev, const void *buf, off_t offset, size_t len)
+{
+ LTRACEF("dev '%s', buf %p, offset %lld, len %zd\n", dev->name, buf, offset, len);
+
+ DEBUG_ASSERT(dev->ref > 0);
+
+ /* range check */
+ if (offset < 0)
+ return -1;
+ if (offset >= dev->size)
+ return 0;
+ if (len == 0)
+ return 0;
+ if (offset + len > dev->size)
+ len = dev->size - offset;
+
+ return dev->write(dev, buf, offset, len);
+}
+
+ssize_t bio_write_block(bdev_t *dev, const void *buf, bnum_t block, uint count)
+{
+ LTRACEF("dev '%s', buf %p, block %d, count %u\n", dev->name, buf, block, count);
+
+ DEBUG_ASSERT(dev->ref > 0);
+
+ /* range check */
+ if (block > dev->block_count)
+ return 0;
+ if (count == 0)
+ return 0;
+ if (block + count > dev->block_count)
+ count = dev->block_count - block;
+
+ return dev->write_block(dev, buf, block, count);
+}
+
+ssize_t bio_erase(bdev_t *dev, off_t offset, size_t len)
+{
+ LTRACEF("dev '%s', offset %lld, len %zd\n", dev->name, offset, len);
+
+ DEBUG_ASSERT(dev->ref > 0);
+
+ /* range check */
+ if (offset < 0)
+ return -1;
+ if (offset >= dev->size)
+ return 0;
+ if (len == 0)
+ return 0;
+ if (offset + len > dev->size)
+ len = dev->size - offset;
+
+ return dev->erase(dev, offset, len);
+}
+
+int bio_ioctl(bdev_t *dev, int request, void *argp)
+{
+ LTRACEF("dev '%s', request %08x, argp %p\n", dev->name, request, argp);
+
+ if (dev->ioctl == NULL) {
+ return ERR_NOT_SUPPORTED;
+ } else {
+ return dev->ioctl(dev, request, argp);
+ }
+}
+
+void bio_initialize_bdev(bdev_t *dev, const char *name, size_t block_size, bnum_t block_count)
+{
+ DEBUG_ASSERT(dev);
+ DEBUG_ASSERT(name);
+ DEBUG_ASSERT(block_size == 512); // XXX can only deal with 512 for now
+
+ list_clear_node(&dev->node);
+ dev->name = strdup(name);
+ dev->block_size = block_size;
+ dev->block_count = block_count;
+ dev->size = (off_t)block_count * block_size;
+ dev->ref = 0;
+
+ /* set up the default hooks, the sub driver should override the block operations at least */
+ dev->read = bio_default_read;
+ dev->read_block = bio_default_read_block;
+ dev->write = bio_default_write;
+ dev->write_block = bio_default_write_block;
+ dev->erase = bio_default_erase;
+ dev->close = NULL;
+}
+
+void bio_register_device(bdev_t *dev)
+{
+ DEBUG_ASSERT(dev);
+
+ LTRACEF(" '%s'\n", dev->name);
+
+ bdev_inc_ref(dev);
+
+ mutex_acquire(&bdevs->lock);
+ list_add_head(&bdevs->list, &dev->node);
+ mutex_release(&bdevs->lock);
+}
+
+void bio_unregister_device(bdev_t *dev)
+{
+ DEBUG_ASSERT(dev);
+
+ LTRACEF(" '%s'\n", dev->name);
+
+ // remove it from the list
+ mutex_acquire(&bdevs->lock);
+ list_delete(&dev->node);
+ mutex_release(&bdevs->lock);
+
+ bdev_dec_ref(dev); // remove the ref the list used to have
+}
+
+void bio_dump_devices(void)
+{
+ printf("block devices:\n");
+ bdev_t *entry;
+ mutex_acquire(&bdevs->lock);
+ list_for_every_entry(&bdevs->list, entry, bdev_t, node) {
+ printf("\t%s, size %lld, bsize %zd, ref %d\n", entry->name, entry->size, entry->block_size, entry->ref);
+ }
+ mutex_release(&bdevs->lock);
+}
+
+void bio_init(void)
+{
+ bdevs = malloc(sizeof(*bdevs));
+
+ list_initialize(&bdevs->list);
+ mutex_init(&bdevs->lock);
+}
+