Revert MMIO space writes on shutdown as needed.

hwaccess.c

 /*
  * This file is part of the flashrom project.
  *
  * Copyright (C) 2009,2010 Carl-Daniel Hailfinger
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
@@ skipping 180 matching lines @@
 
 uint16_t mmio_le_readw(void *addr)
 {
         return le_to_cpu16(mmio_readw(addr));
 }
 
 uint32_t mmio_le_readl(void *addr)
 {
         return le_to_cpu32(mmio_readl(addr));
 }
+
+enum mmio_write_type {
+        mmio_write_type_b,
+        mmio_write_type_w,
+        mmio_write_type_l,
+};
+
+struct undo_mmio_write_data {
+        void *addr;
+        int reg;
+        enum mmio_write_type type;
+        union {
+                uint8_t bdata;
+                uint16_t wdata;
+                uint32_t ldata;
+        };
+};
+
+void undo_mmio_write(void *p)
+{
+        struct undo_mmio_write_data *data = p;
+        msg_pdbg("Restoring MMIO space at %p\n", data->addr);
+        switch (data->type) {
+        case mmio_write_type_b:
+                mmio_writeb(data->bdata, data->addr);
+                break;
+        case mmio_write_type_w:
+                mmio_writew(data->wdata, data->addr);
+                break;
+        case mmio_write_type_l:
+                mmio_writel(data->ldata, data->addr);
+                break;
+        }
+        /* p was allocated in register_undo_mmio_write. */
+        free(p);
+}
+
+#define register_undo_mmio_write(a, c)                                  \
+{                                                                       \
+        struct undo_mmio_write_data *undo_mmio_write_data;              \
+        undo_mmio_write_data = malloc(sizeof(struct undo_mmio_write_data)); \
+        undo_mmio_write_data->addr = a;                                 \
+        undo_mmio_write_data->type = mmio_write_type_##c;               \
+        undo_mmio_write_data->c##data = mmio_read##c(a);                \
+        register_shutdown(undo_mmio_write, undo_mmio_write_data);       \
+}
+
+#define register_undo_mmio_writeb(a) register_undo_mmio_write(a, b)
+#define register_undo_mmio_writew(a) register_undo_mmio_write(a, w)
+#define register_undo_mmio_writel(a) register_undo_mmio_write(a, l)
+
+void rmmio_writeb(uint8_t val, void *addr)
+{
+        register_undo_mmio_writeb(addr);
+        mmio_writeb(val, addr);
+}
+
+void rmmio_writew(uint16_t val, void *addr)
+{
+        register_undo_mmio_writew(addr);
+        mmio_writew(val, addr);
+}
+
+void rmmio_writel(uint32_t val, void *addr)
+{
+        register_undo_mmio_writel(addr);
+        mmio_writel(val, addr);
+}