commonlib: provide incoherent region device

The MRC cache uses an incoherent mechanism for updating the
cache contents in that it assumes memory mapped boot device
access for checking against latest data for update. However,
it uses another driver for updating the underlying storage
area.

In order to aid in moving the MRC cache over to using
region_devices for updates provide an implementation of
a region_device which performs reads and writes to different
region_devices so that different drivers can be used
transparently.

BUG=chrome-os-partner:56151

Change-Id: I30e858245c30cbccd6313aff5ebecd3fd98d7302
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/17716
Tested-by: build bot (Jenkins)
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Duncan Laurie <dlaurie@chromium.org>

1 files changed, 79 insertions, 0 deletions

diff --git a/src/commonlib/region.c b/src/commonlib/region.c
index ac0faf111f..bf53b9dda8 100644
--- a/src/commonlib/region.c
+++ b/src/commonlib/region.c
@@ -437,3 +437,82 @@ const struct region_device_ops xlate_rdev_rw_ops = {
 	.writeat = xlate_writeat,
 	.eraseat = xlate_eraseat,
 };
+
+
+static void *incoherent_mmap(const struct region_device *rd, size_t offset,
+				size_t size)
+{
+	const struct incoherent_rdev *irdev;
+
+	irdev = container_of(rd, const struct incoherent_rdev, rdev);
+
+	return rdev_mmap(irdev->read, offset, size);
+}
+
+static int incoherent_munmap(const struct region_device *rd, void *mapping)
+{
+	const struct incoherent_rdev *irdev;
+
+	irdev = container_of(rd, const struct incoherent_rdev, rdev);
+
+	return rdev_munmap(irdev->read, mapping);
+}
+
+static ssize_t incoherent_readat(const struct region_device *rd, void *b,
+				size_t offset, size_t size)
+{
+	const struct incoherent_rdev *irdev;
+
+	irdev = container_of(rd, const struct incoherent_rdev, rdev);
+
+	return rdev_readat(irdev->read, b, offset, size);
+}
+
+static ssize_t incoherent_writeat(const struct region_device *rd, const void *b,
+			size_t offset, size_t size)
+{
+	const struct incoherent_rdev *irdev;
+
+	irdev = container_of(rd, const struct incoherent_rdev, rdev);
+
+	return rdev_writeat(irdev->write, b, offset, size);
+}
+
+static ssize_t incoherent_eraseat(const struct region_device *rd, size_t offset,
+				size_t size)
+{
+	const struct incoherent_rdev *irdev;
+
+	irdev = container_of(rd, const struct incoherent_rdev, rdev);
+
+	return rdev_eraseat(irdev->write, offset, size);
+}
+
+static const struct region_device_ops incoherent_rdev_ops = {
+	.mmap = incoherent_mmap,
+	.munmap = incoherent_munmap,
+	.readat = incoherent_readat,
+	.writeat = incoherent_writeat,
+	.eraseat = incoherent_eraseat,
+};
+
+const struct region_device *incoherent_rdev_init(struct incoherent_rdev *irdev,
+				const struct region *r,
+				const struct region_device *read,
+				const struct region_device *write)
+{
+	const size_t size = region_sz(r);
+
+	if (size != region_device_sz(read) || size != region_device_sz(write))
+		return NULL;
+
+	/* The region is represented as offset 0 to size. That way, the generic
+	 * rdev operations can be called on the read or write implementation
+	 * without any unnecessary translation because the offsets all start
+	 * at 0. */
+	region_device_init(&irdev->rdev, &incoherent_rdev_ops, 0, size);
+	irdev->read = read;
+	irdev->write = write;
+
+	return &irdev->rdev;
+}