Add and enable direct PNOR access mode

This avoids having to cache the PNOR at BMC startup, at
a small IPL speed cost.

kestrel/src/ipmi_bt.h

-// © 2020 Raptor Engineering, LLC
+// © 2020 - 2021 Raptor Engineering, LLC
 //
 // Released under the terms of the GPL v3
 // See the LICENSE file for full details
@@ -115,6 +115,9 @@
 #define HIOMAP_SUGGESTED_TIMEOUT_S 15
 #define HIOMAP_PNOR_DEVICE_COUNT   1
 
+#define HIOMAP_MAX_DIRTY_RANGES    128
+#define HIOMAP_MAX_WRITE_WINDOWS   128
+
 // 4k block size
 // Requires subsector erase capability
 #define FLASH_BLOCK_SIZE_SHIFT 12
@@ -143,6 +146,14 @@ typedef struct hiomap_pnor_dirty_range
     uint8_t erased;
 } hiomap_pnor_dirty_range_t;
 
+typedef struct hiomap_pnor_write_window
+{
+    uint32_t start_address;
+    uint32_t bytes;
+    uint8_t active;
+    uint8_t *buffer;
+} hiomap_pnor_write_window_t;
+
 typedef struct hiomap_configuration_data
 {
     uint8_t protocol_version;
@@ -151,7 +162,9 @@ typedef struct hiomap_configuration_data
     uint8_t active_device_id;
     uint8_t window_type;
     uint8_t dirty_range_count;
-    hiomap_pnor_dirty_range_t dirty_ranges[128];
+    hiomap_pnor_dirty_range_t dirty_ranges[HIOMAP_MAX_DIRTY_RANGES];
+    uint8_t write_window_count;
+    hiomap_pnor_write_window_t write_windows[HIOMAP_MAX_WRITE_WINDOWS];
 } hiomap_configuration_data_t;
 
 typedef struct __attribute__((packed)) ipmi_request_message