[coreboot-gerrit] Patch set updated for coreboot: lib/boot_device: add RW boot device construct

[Aaron Durbin (adurbin@chromium.org)]

Aaron Durbin (adurbin at chromium.org) just uploaded a new patch set to gerrit, which you can find at https://review.coreboot.org/16194

-gerrit

commit 03dc8986dce390e84b26747dd5291c86421130d1
Author: Aaron Durbin <adurbin at chromium.org>
Date:   Wed Aug 10 11:42:42 2016 -0500

    lib/boot_device: add RW boot device construct
    
    The current boot device usage assumes read-only semantics to
    the boot device. Any time someone wants to write to the
    boot device a device-specific API is invoked such as SPI flash.
    Instead, provide a mechanism to retrieve an object that can
    be used to perform writes to the boot device. On systems where
    the implementations are symmetric these devices can be treated
    one-in-the-same. However, for x86 systems with memory mapped SPI
    the read-only boot device provides different operations.
    
    BUG=chrome-os-partner:55932
    
    Change-Id: I0af324824f9e1a8e897c2453c36e865b59c4e004
    Signed-off-by: Aaron Durbin <adurbin at chromium.org>
---
 src/include/boot_device.h | 16 ++++++++++++++++
 src/lib/boot_device.c     | 24 ++++++++++++++++++------
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/src/include/boot_device.h b/src/include/boot_device.h
index 3964a95..cc70442 100644
--- a/src/include/boot_device.h
+++ b/src/include/boot_device.h
@@ -18,9 +18,18 @@
 
 #include <commonlib/region.h>
 
+/*
+ * Please note that the read-only boot device may not be coherent with
+ * the read-write boot device. Thus, mixing mmap() and writeat() is
+ * most likely not to work so don't rely on such semantics.
+ */
+
 /* Return the region_device for the read-only boot device. */
 const struct region_device *boot_device_ro(void);
 
+/* Return the region_device for the read-write boot device. */
+const struct region_device *boot_device_rw(void);
+
 /*
  * Create a sub-region of the read-only boot device.
  * Returns 0 on success, < 0 on error.
@@ -29,6 +38,13 @@ int boot_device_ro_subregion(const struct region *sub,
 				struct region_device *subrd);
 
 /*
+ * Create a sub-region of the read-write boot device.
+ * Returns 0 on success, < 0 on error.
+ */
+int boot_device_rw_subregion(const struct region *sub,
+				struct region_device *subrd);
+
+/*
  * Initialize the boot device. This may be called multiple times within
  * a stage so boot device implementations should account for this behavior.
  **/
diff --git a/src/lib/boot_device.c b/src/lib/boot_device.c
index 42fe5df..e7968f4 100644
--- a/src/lib/boot_device.c
+++ b/src/lib/boot_device.c
@@ -20,18 +20,30 @@ void __attribute__((weak)) boot_device_init(void)
 	/* Provide weak do-nothing init. */
 }
 
+static int boot_device_subregion(const struct region *sub,
+				struct region_device *subrd,
+				const struct region_device *parent)
+{
+	if (parent == NULL)
+		return -1;
+
+	return rdev_chain(subrd, parent, region_offset(sub), region_sz(sub));
+}
+
 int boot_device_ro_subregion(const struct region *sub,
 				struct region_device *subrd)
 {
-	const struct region_device *boot_dev;
-
 	/* Ensure boot device has been initialized at least once. */
 	boot_device_init();
 
-	boot_dev = boot_device_ro();
+	return boot_device_subregion(sub, subrd, boot_device_ro());
+}
 
-	if (boot_dev == NULL)
-		return -1;
+int boot_device_rw_subregion(const struct region *sub,
+				struct region_device *subrd)
+{
+	/* Ensure boot device has been initialized at least once. */
+	boot_device_init();
 
-	return rdev_chain(subrd, boot_dev, region_offset(sub), region_sz(sub));
+	return boot_device_subregion(sub, subrd, boot_device_rw());
 }