phase2: simplify the bootloader_second_phase mega-loop

This puts the loop body in a new function called try_this_kernel.
As an added benefit, we can drop one level of indentation.

This change is hard to read as a patch. It gets better if one just
applies it and then looks at it with "git diff -w" or similar.

Signed-off-by: Werner Almesberger <werner@openmoko.org>

qiboot/src/phase2.c

@@ -96,23 +96,16 @@ int read_file(const char * filepath, u8 * destination, int size)
 	return len;
 }
 
-void bootloader_second_phase(void)
+static void try_this_kernel(void)
 {
 	void	(*the_kernel)(int zero, int arch, uint params);
-	int kernel = 0;
 	const struct board_variant * board_variant =
 					      (this_board->get_board_variant)();
 	unsigned int initramfs_len = 0;
 	static char commandline_rootfs_append[512] = "";
+	static void * last_block_init = NULL;
+	static int last_block_init_result = 0;
 	int ret;
-	void * last_block_init = NULL;
-	int last_block_init_result = 0;
-
-	/* we try the possible kernels for this board in order */
-
-	this_kernel = &this_board->kernel_source[kernel++];
-
-	while (this_kernel->name) {
 	const char *p;
 	char * cmdline;
 	struct tag *params = (struct tag *)this_board->linux_tag_placement;
@@ -140,17 +133,14 @@ void bootloader_second_phase(void)
 		 * block device to one time
 		 */
 		if (this_kernel->block_init != last_block_init)
-				last_block_init_result =
+			last_block_init_result = (this_kernel->block_init)();
-						    (this_kernel->block_init)();
 
 		if (last_block_init_result) {
 			puts("block device init failed\n");
 			if (this_kernel->block_init != last_block_init)
 				indicate(UI_IND_MOUNT_FAIL);
-				this_kernel = &this_board->
+			last_block_init = this_kernel[1].block_init;
-							kernel_source[kernel++];
+			return;
-				last_block_init = this_kernel->block_init;
-				continue;
 		}
 		last_block_init = this_kernel->block_init;
 	}
@@ -161,25 +151,19 @@ void bootloader_second_phase(void)
 	if (this_kernel->partition_index) {
 		unsigned char *p = kernel_dram;
 
-			if ((int)this_kernel->block_read(kernel_dram, 0, 4)
+		if ((int)this_kernel->block_read(kernel_dram, 0, 4) < 0) {
-									  < 0) {
 			puts("Bad partition read\n");
-				this_kernel = &this_board->
-							kernel_source[kernel++];
 			indicate(UI_IND_MOUNT_FAIL);
-				continue;
+			return;
 		}
 
 		if ((p[0x1fe] != 0x55) || (p[0x1ff] != 0xaa)) {
 			puts("partition signature missing\n");
-				this_kernel = &this_board->
-							kernel_source[kernel++];
 			indicate(UI_IND_MOUNT_FAIL);
-				continue;
+			return;
 		}
 
-			p += 0x1be + 8 + (0x10 *
+		p += 0x1be + 8 + (0x10 * (this_kernel->partition_index - 1));
-					    (this_kernel->partition_index - 1));
 
 		partition_offset_blocks = (((u32)p[3]) << 24) |
 					  (((u32)p[2]) << 16) |
@@ -213,24 +197,20 @@ void bootloader_second_phase(void)
 			puts(")\n");
 			indicate(UI_IND_SKIPPING);
 		}
-			this_kernel = &this_board->kernel_source[kernel++];
+		return;
-			continue;
 	}
 
 	/* is there a commandline append file? */
 
 	commandline_rootfs_append[0] = '\0';
-		read_file(this_board->append, (u8 *)commandline_rootfs_append,
+	read_file(this_board->append, (u8 *)commandline_rootfs_append, 512);
-									   512);
 
 	indicate(UI_IND_KERNEL_PULL);
 
 	/* pull the kernel image */
 
-		if (read_file(this_kernel->filepath, kernel_dram, 4096) < 0) {
+	if (read_file(this_kernel->filepath, kernel_dram, 4096) < 0)
-			this_kernel = &this_board->kernel_source[kernel++];
+		return;
-			continue;
-		}
 
 	hdr = (image_header_t *)kernel_dram;
 
@@ -238,8 +218,7 @@ void bootloader_second_phase(void)
 		puts("bad magic ");
 		print32(hdr->ih_magic);
 		puts("\n");
-			this_kernel = &this_board->kernel_source[kernel++];
+		return;
-			continue;
 	}
 
 	puts("        Found: \"");
@@ -251,11 +230,9 @@ void bootloader_second_phase(void)
 	kernel_size = ((__be32_to_cpu(hdr->ih_size) +
 			  sizeof(image_header_t) + 2048) & ~(2048 - 1));
 
-		if (read_file(this_kernel->filepath, kernel_dram,
+	if (read_file(this_kernel->filepath, kernel_dram, kernel_size) < 0) {
-							     kernel_size) < 0) {
-			this_kernel = &this_board->kernel_source[kernel++];
 		indicate(UI_IND_KERNEL_PULL_FAIL);
-			continue;
+		return;
 	}
 
 	indicate(UI_IND_KERNEL_PULL_OK);
@@ -269,9 +246,8 @@ void bootloader_second_phase(void)
 						      16 * 1024 * 1024);
 		if (initramfs_len < 0) {
 			puts("initramfs load failed\n");
-				this_kernel = &this_board->kernel_source[kernel++];
 			indicate(UI_IND_INITRAMFS_PULL_FAIL);
-				continue;
+			return;
 		}
 		indicate(UI_IND_INITRAMFS_PULL_OK);
 	}
@@ -289,8 +265,7 @@ void bootloader_second_phase(void)
 		puts(" vs hdr CRC 0x");
 		print32(__be32_to_cpu(hdr->ih_dcrc));
 		puts("\n");
-			this_kernel = &this_board->kernel_source[kernel++];
+		return;
-			continue;
 	}
 
 	the_kernel = (void (*)(int, int, uint))
@@ -344,8 +319,7 @@ void bootloader_second_phase(void)
 	 * to have the debugging options added to the commandline
 	 */
 
-		if (this_board->commandline_board_debug &&
+	if (this_board->commandline_board_debug && this_board->get_ui_keys)
-							this_board->get_ui_keys)
 		if ((this_board->get_ui_keys)() & UI_ACTION_SKIPKERNEL)
 			cmdline += strlen(strcpy(cmdline, this_board->
 					      commandline_board_debug));
@@ -383,6 +357,14 @@ void bootloader_second_phase(void)
 	/* we won't come back here no matter what */
 }
 
+void bootloader_second_phase(void)
+{
+	/* we try the possible kernels for this board in order */
+
+	for (this_kernel = this_board->kernel_source; this_kernel->name;
+	    this_kernel++)
+		try_this_kernel();
+
 	/* none of the kernels worked out */
 
 	puts("\nNo usable kernel image found\n");