intel_reg_dumper: Add support for reading register dumps from files

Also add intel_reg_snapshot for creating such snapshots, and relevant
documentation.

Signed-off-by: Adam Jackson <ajax@redhat.com>

lib/intel_gpu_tools.c

@@ -25,12 +25,17 @@
  *
  */
 
+#include <unistd.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <errno.h>
 #include <err.h>
 #include <assert.h>
 #include <sys/ioctl.h>
+#include <sys/fcntl.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
 #include "intel_gpu_tools.h"
 #include "i915_drm.h"
 #include "intel_batchbuffer.h"
@@ -82,6 +87,28 @@ intel_get_pci_device(void)
 	devid = pci_dev->device_id;
 }
 
+void
+intel_map_file(char *file)
+{
+	int fd;
+	struct stat st;
+
+	fd = open(file, O_RDWR);
+	if (fd == -1) {
+		    fprintf(stderr, "Couldn't open %s: %s\n", file,
+			    strerror(errno));
+		    exit(1);
+	}
+	fstat(fd, &st);
+	mmio = mmap(NULL, st.st_size, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+	if (mmio == MAP_FAILED) {
+		    fprintf(stderr, "Couldn't mmap %s: %s\n", file,
+			    strerror(errno));
+		    exit(1);
+	}
+	close(fd);
+}
+
 void
 intel_get_mmio(void)
 {

lib/intel_gpu_tools.h

@@ -56,3 +56,4 @@ void intel_get_drm_devid(int fd);
 void intel_copy_bo(struct intel_batchbuffer *batch,
 		   drm_intel_bo *dst_bo, drm_intel_bo *src_bo,
 		   int width, int height);
+void intel_map_file(char *);