libflashrom,writeprotect: add functions for reading/writing WP configs

New functions are exposed through the libflashrom API for
reading/writing chip's WP settins: `flashrom_wp_{read,write}_cfg()`.

They read/write an opaque `struct flashrom_wp_cfg` instance, which
includes the flash protection range and status register protection mode.

This commit also adds `{read,write}_wp_bits()` helper functions that
read/write chip-specific WP configuration bits.

Tested: flashrom --wp-{enable,disable,range,list,status} at end of patch series

Change-Id: I3ad25708c3321b8fb0216c3eaf6ffc07616537ad
Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/58479
Original-Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Original-Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/writeprotect.h b/writeprotect.h
index 2f473f7..d54befa 100644
--- a/writeprotect.h
+++ b/writeprotect.h
@@ -22,8 +22,21 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#include "libflashrom.h"
+
 #define MAX_BP_BITS 4
 
+/* Chip protection range: start address and length. */
+struct wp_range {
+        size_t start, len;
+};
+
+/* Generic description of a chip's write protection configuration. */
+struct flashrom_wp_cfg {
+        enum flashrom_wp_mode mode;
+        struct wp_range range;
+};
+
 /*
  * Description of a chip's write protection configuration.
  *
@@ -56,4 +69,12 @@
 	uint8_t bp[MAX_BP_BITS];
 };
 
+struct flashrom_flashctx;
+
+/* Write WP configuration to the chip */
+enum flashrom_wp_result wp_write_cfg(struct flashrom_flashctx *, const struct flashrom_wp_cfg *);
+
+/* Read WP configuration from the chip */
+enum flashrom_wp_result wp_read_cfg(struct flashrom_wp_cfg *, struct flashrom_flashctx *);
+
 #endif /* !__WRITEPROTECT_H__ */