disk: Support a non-fixed (logical) SECTOR_SIZE

 This allows a single build to support ATA drives with (eg) 512B and 4K
 logical sector sizes.  This is needed because ATA drives are user-
 replaceable and we don't know what could get plugged in.

 * Add disk_get_log_sector_size() API  (no-op for non-ATA storage)
 * Mostly a no-op if MAX_LOG_SECTOR_SIZE is not enabled
 * Sanity-check that storage's logical sector size is not larger
   than what we're built for

NOTE:  Other layers (eg ATA, FAT, etc) still need to be made aware of this.

Change-Id: Id6183ef0573cb0778fa9a91302e600c3e710eebd

1 files changed, 3 insertions, 1 deletions

diff --git a/firmware/export/disk.h b/firmware/export/disk.h
index a19e011170..4f11438b1b 100644
--- a/firmware/export/disk.h
+++ b/firmware/export/disk.h
@@ -47,10 +47,12 @@ int disk_mount(int drive);
 int disk_unmount_all(void);
 int disk_unmount(int drive);
 
-/* The number of 512-byte sectors in a "logical" sector. Needed for ipod 5.5G */
+/* Used when the drive's logical sector size is smaller than the sector size used by the partition table and filesystem.  Notably needed for ipod 5.5G/6G. */
 #ifdef MAX_LOG_SECTOR_SIZE
 int disk_get_sector_multiplier(IF_MD_NONVOID(int drive));
 #endif
+/* The size of the drive's smallest addressible unit */
+int disk_get_log_sector_size(IF_MD_NONVOID(int drive));
 
 bool disk_present(IF_MD_NONVOID(int drive));