pstore/ram: Add kern-doc for struct persistent_ram_zone

The struct persistent_ram_zone wasn't well documented. This adds kern-doc
for it.
Signed-off-by: Kees Cook <keescook@chromium.org>

fs/pstore/ram_core.c

@@ -29,6 +29,16 @@
 #include <linux/vmalloc.h>
 #include <asm/page.h>
 
+/**
+ * struct persistent_ram_buffer - persistent circular RAM buffer
+ *
+ * @sig:
+ *	signature to indicate header (PERSISTENT_RAM_SIG xor PRZ-type value)
+ * @start:
+ *	offset into @data where the beginning of the stored bytes begin
+ * @size:
+ *	number of valid bytes stored in @data
+ */
 struct persistent_ram_buffer {
 	uint32_t    sig;
 	atomic_t    start;

include/linux/pstore_ram.h

@@ -30,6 +30,10 @@
  * PRZ_FLAG_NO_LOCK is used. For all other cases, locking is required.
  */
 #define PRZ_FLAG_NO_LOCK	BIT(0)
+/*
+ * If a PRZ should only have a single-boot lifetime, this marks it as
+ * getting wiped after its contents get copied out after boot.
+ */
 #define PRZ_FLAG_ZAP_OLD	BIT(1)
 
 struct persistent_ram_buffer;
@@ -43,17 +47,53 @@ struct persistent_ram_ecc_info {
 	uint16_t *par;
 };
 
+/**
+ * struct persistent_ram_zone - Details of a persistent RAM zone (PRZ)
+ *                              used as a pstore backend
+ *
+ * @paddr:	physical address of the mapped RAM area
+ * @size:	size of mapping
+ * @label:	unique name of this PRZ
+ * @flags:	holds PRZ_FLAGS_* bits
+ *
+ * @buffer_lock:
+ *	locks access to @buffer "size" bytes and "start" offset
+ * @buffer:
+ *	pointer to actual RAM area managed by this PRZ
+ * @buffer_size:
+ *	bytes in @buffer->data (not including any trailing ECC bytes)
+ *
+ * @par_buffer:
+ *	pointer into @buffer->data containing ECC bytes for @buffer->data
+ * @par_header:
+ *	pointer into @buffer->data containing ECC bytes for @buffer header
+ *	(i.e. all fields up to @data)
+ * @rs_decoder:
+ *	RSLIB instance for doing ECC calculations
+ * @corrected_bytes:
+ *	ECC corrected bytes accounting since boot
+ * @bad_blocks:
+ *	ECC uncorrectable bytes accounting since boot
+ * @ecc_info:
+ *	ECC configuration details
+ *
+ * @old_log:
+ *	saved copy of @buffer->data prior to most recent wipe
+ * @old_log_size:
+ *	bytes contained in @old_log
+ *
+ */
 struct persistent_ram_zone {
 	phys_addr_t paddr;
 	size_t size;
 	void *vaddr;
 	char *label;
-	struct persistent_ram_buffer *buffer;
-	size_t buffer_size;
 	u32 flags;
+
 	raw_spinlock_t buffer_lock;
+	struct persistent_ram_buffer *buffer;
+	size_t buffer_size;
 
-	/* ECC correction */
 	char *par_buffer;
 	char *par_header;
 	struct rs_control *rs_decoder;