cr50: complete support of the new NVMEM structure

This patch eliminates unnecessary legacy nvmem.c and nvmem_vars.c code
and brings the code base to the state where the new NVMEM layout is
fully functional.

BRANCH=cr50, cr50-mp
BUG=b:69907320, b:129710256
CQ-DEPEND=CL:1450278
TEST=the following tests pass:
   - test cases in ./test/nvmem.c

   - TCG suite (passes on par with the existing Cr50 code with the
     reduced code footprint TPM2 library)

   - Chrome OS device migrates from legacy to new implementation with
     user account maintained.

   - Chrome OS user account is maintained over AP and H1 reboots and
     deep sleep cycles.

Change-Id: If4bc2dd125873a79dbe0e268eb32100a8b8b352d
Signed-off-by: Vadim Bendebury <vbendeb@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1496607
Reviewed-by: Andrey Pronin <apronin@chromium.org>

1 files changed, 32 insertions, 3 deletions

diff --git a/include/nvmem_vars.h b/include/nvmem_vars.h
index add14345e7..eec1e757a2 100644
--- a/include/nvmem_vars.h
+++ b/include/nvmem_vars.h
@@ -65,12 +65,32 @@ struct tuple {
 int initvars(void);
 
 /*
- * Look up a key, return a pointer to the tuple. If the key is not found,
- * return NULL. WARNING: The returned pointer is only valid until the next call
- * to setvar() or writevars(). Use it or lose it.
+ * Look up the key passed in the input tuple and fill the value, if found.
+ *
+ * The val_len field in the passed in tuple indicates how much room is
+ * available, the actual value size could be smaller.
+ *
+ * Return:
+ *
+ * EC_SUCCESS - if the key was found and there was enough room in the passed
+ *              in tuple for the value.
+ * EC_ERROR_INVAL - if the key was not found.
+ *
+ * EC_ERROR_MEMORY_ALLOCATION - if the value would not fit into the supplied
+ *              tuple.
  */
 const struct tuple *getvar(const uint8_t *key, uint8_t key_len);
 
+/*
+ * Free memory held by the previously read tuple.
+ *
+ * Note that tuple address is not the address to be returned to the heap, so
+ * the user must use this function to free this memory. If var is NULL this
+ * function is a no-op.
+ *
+ */
+void freevar(const struct tuple *var);
+
 /* Use these to access the data components of a valid struct tuple pointer */
 const uint8_t *tuple_key(const struct tuple *);
 const uint8_t *tuple_val(const struct tuple *);
@@ -88,6 +108,15 @@ int setvar(const uint8_t *key, uint8_t key_len,
  */
 int writevars(void);
 
+/*
+ * A fully contained function which does not use any available nvmem_vars
+ * methods, as it is used solely for retrieving vars from legacy storage
+ * format. Runs only during migration.
+ */
+const struct tuple *legacy_getnextvar(const struct tuple *prev_var);
+
+int set_local_copy(void);
+
 #ifdef __cplusplus
 }
 #endif