rv32: add software interface to dirty bit tracking

rv32/dirty.h

@@ -0,0 +1,46 @@
+#ifndef DIRTY_H
+#define DIRTY_H
+
+#include "compiler.h"
+#include "ioregs.h"
+
+#define DIRTY_PAGE_BITS		12
+#define DIRTY_PAGE_SIZE		(1U << DIRTY_PAGE_BITS)
+#define DIRTY_PAGES		(1U << (SDRAM_BITS - DIRTY_PAGE_BITS))
+#define DIRTY_PAGE_MASK		(DIRTY_PAGES - 1)
+
+static inline size_t dirty_page_num(const void *addr)
+{
+    return ((size_t)addr - SDRAM_ADDR) >> DIRTY_PAGE_BITS;
+}
+
+static inline volatile bool *dirty_page_reg(size_t page)
+{
+    return (volatile bool *)(&DIRTY_PAGE_REG + page);
+}
+
+static inline bool is_dirty_page(size_t page)
+{
+    volatile bool *dreg = dirty_page_reg(page);
+    return *dreg;
+}
+
+static inline bool mem_dirty(const void *addr)
+{
+    return is_dirty_page(dirty_page_num(addr));
+}
+
+static inline bool is_dirty_page_clear(size_t page)
+{
+    volatile bool *dreg = dirty_page_reg(page);
+    bool d = *dreg;
+    *dreg = d;
+    return d;
+}
+
+static inline bool mem_dirty_clear(const void *addr)
+{
+    return is_dirty_page_clear(dirty_page_num(addr));
+}
+
+#endif /* DIRTY_H */

rv32/ioregs.h

@@ -168,4 +168,6 @@
 #define USBDESC_ROM		IODEVL(USBDESC,0)
 #define usbdesc_rom		PTR(USBDESC_ROM)
 
+#define DIRTY_PAGE_REG		IODEVL(DIRTY,0)
+
 #endif /* IODEV_H */