fastboot: Add support for flashing zImage

diff --git a/common/fb_mmc.c b/common/fb_mmc.c
index 866982e41c..5fb2b05845 100644
--- a/common/fb_mmc.c
+++ b/common/fb_mmc.c
@@ -4,6 +4,7 @@ 
  * SPDX-License-Identifier:	GPL-2.0+
  */
 
+#include <android_image.h>
 #include <config.h>
 #include <common.h>
 #include <blk.h>
@@ -11,6 +12,7 @@ 
 #include <fb_mmc.h>
 #include <image-sparse.h>
 #include <part.h>
+#include <linux/compat.h>
 #include <mmc.h>
 #include <div64.h>
 
@@ -27,6 +29,8 @@ 
 #define CONFIG_FASTBOOT_MBR_NAME "mbr"
 #endif
 
+#define BOOT_PARTITION_NAME "boot"
+
 struct fb_mmc_sparse {
 	struct blk_desc	*dev_desc;
 };
@@ -99,6 +103,163 @@  static void write_raw_image(struct blk_desc *dev_desc, disk_partition_t *info,
 	fastboot_okay("");
 }
 
+/**
+ * Read Android boot image header from boot partition.
+ *
+ * @param[in] dev_desc MMC device descriptor
+ * @param[in] info Boot partition info
+ * @param[out] hdr Where to store read boot image header
+ *
+ * @return Boot image header sectors count or 0 on error
+ */
+static lbaint_t fb_mmc_get_boot_header(struct blk_desc *dev_desc,
+				       disk_partition_t *info,
+				       struct andr_img_hdr *hdr)
+{
+	ulong sector_size;		/* boot partition sector size */
+	lbaint_t hdr_sectors;		/* boot image header sectors count */
+	int res;
+
+	/* Calculate boot image sectors count */
+	sector_size = info->blksz;
+	hdr_sectors = DIV_ROUND_UP(sizeof(struct andr_img_hdr), sector_size);
+	if (hdr_sectors == 0) {
+		error("invalid number of boot sectors: 0");
+		fastboot_fail("invalid number of boot sectors: 0");
+		return 0;
+	}
+
+	/* Read the boot image header */
+	res = dev_desc->block_read(dev_desc, info->start, hdr_sectors,
+				   (void *)hdr);
+	if (res == 0) {
+		error("cannot read header from boot partition");
+		fastboot_fail("cannot read header from boot partition");
+		return 0;
+	}
+
+	/* Check boot header magic string */
+	res = android_image_check_header(hdr);
+	if (res != 0) {
+		error("bad boot image magic");
+		fastboot_fail("boot partition not initialized");
+		return 0;
+	}
+
+	return hdr_sectors;
+}
+
+/**
+ * Write downloaded zImage to boot partition and repack it properly.
+ *
+ * @param dev_desc MMC device descriptor
+ * @param download_buffer Address to fastboot buffer with zImage in it
+ * @param download_bytes Size of fastboot buffer, in bytes
+ *
+ * @return 0 on success or -1 on error
+ */
+static int fb_mmc_update_zimage(struct blk_desc *dev_desc,
+				void *download_buffer,
+				unsigned int download_bytes)
+{
+	u32 hdr_addr;				/* boot image header address */
+	struct andr_img_hdr *hdr;		/* boot image header */
+	lbaint_t hdr_sectors;			/* boot image header sectors */
+	u8 *ramdisk_buffer;
+	u32 ramdisk_sector_start;
+	u32 ramdisk_sectors;
+	u32 kernel_sector_start;
+	u32 kernel_sectors;
+	u32 sectors_per_page;
+	disk_partition_t info;
+	int res;
+
+	puts("Flashing zImage\n");
+
+	/* Get boot partition info */
+	res = part_get_info_by_name(dev_desc, BOOT_PARTITION_NAME, &info);
+	if (res < 0) {
+		error("cannot find boot partition");
+		fastboot_fail("cannot find boot partition");
+		return -1;
+	}
+
+	/* Put boot image header in fastboot buffer after downloaded zImage */
+	hdr_addr = (u32)download_buffer + PAGE_ALIGN(download_bytes);
+	hdr = (struct andr_img_hdr *)hdr_addr;
+
+	/* Read boot image header */
+	hdr_sectors = fb_mmc_get_boot_header(dev_desc, &info, hdr);
+	if (hdr_sectors == 0) {
+		error("unable to read boot image header");
+		fastboot_fail("unable to read boot image header");
+		return -1;
+	}
+
+	/* Check if boot image has second stage in it (we don't support it) */
+	if (hdr->second_size > 0) {
+		error("moving second stage is not supported yet");
+		fastboot_fail("moving second stage is not supported yet");
+		return -1;
+	}
+
+	/* Extract ramdisk location */
+	sectors_per_page = hdr->page_size / info.blksz;
+	ramdisk_sector_start = info.start + sectors_per_page;
+	ramdisk_sector_start += DIV_ROUND_UP(hdr->kernel_size, hdr->page_size) *
+					     sectors_per_page;
+	ramdisk_sectors = DIV_ROUND_UP(hdr->ramdisk_size, hdr->page_size) *
+				       sectors_per_page;
+
+	/* Read ramdisk and put it in fastboot buffer after boot image header */
+	ramdisk_buffer = (u8 *)hdr + (hdr_sectors * info.blksz);
+	res = dev_desc->block_read(dev_desc, ramdisk_sector_start,
+				   ramdisk_sectors, ramdisk_buffer);
+	if (res == 0) {
+		error("cannot read ramdisk from boot partition");
+		fastboot_fail("cannot read ramdisk from boot partition");
+		return -1;
+	}
+
+	/* Write new kernel size to boot image header */
+	hdr->kernel_size = download_bytes;
+	res = dev_desc->block_write(dev_desc, info.start,
+				    hdr_sectors, (void *)hdr);
+	if (res == 0) {
+		error("cannot writeback boot image header");
+		fastboot_fail("cannot write back boot image header");
+		return -1;
+	}
+
+	/* Write the new downloaded kernel */
+	kernel_sector_start = info.start + sectors_per_page;
+	kernel_sectors = DIV_ROUND_UP(hdr->kernel_size, hdr->page_size) *
+				      sectors_per_page;
+	res = dev_desc->block_write(dev_desc, kernel_sector_start,
+				    kernel_sectors, download_buffer);
+	if (res == 0) {
+		error("cannot write new kernel");
+		fastboot_fail("cannot write new kernel");
+		return -1;
+	}
+
+	/* Write the saved ramdisk back */
+	ramdisk_sector_start = info.start + sectors_per_page;
+	ramdisk_sector_start += DIV_ROUND_UP(hdr->kernel_size, hdr->page_size) *
+					     sectors_per_page;
+	res = dev_desc->block_write(dev_desc, ramdisk_sector_start,
+				    ramdisk_sectors, ramdisk_buffer);
+	if (res == 0) {
+		error("cannot write back original ramdisk");
+		fastboot_fail("cannot write back original ramdisk");
+		return -1;
+	}
+
+	puts("........ zImage was updated in boot partition\n");
+	fastboot_okay("");
+	return 0;
+}
+
 void fb_mmc_flash_write(const char *cmd, void *download_buffer,
 			unsigned int download_bytes)
 {
@@ -153,6 +314,11 @@  void fb_mmc_flash_write(const char *cmd, void *download_buffer,
 	}
 #endif
 
+	if (strcmp(cmd, "zImage") == 0 || strcmp(cmd, "zimage") == 0) {
+		fb_mmc_update_zimage(dev_desc, download_buffer, download_bytes);
+		return;
+	}
+
 	if (part_get_info_by_name_or_alias(dev_desc, cmd, &info) < 0) {
 		error("cannot find partition: '%s'\n", cmd);
 		fastboot_fail("cannot find partition");
diff --git a/include/android_image.h b/include/android_image.h
index dfd4d9d72c..c058b1d388 100644
--- a/include/android_image.h
+++ b/include/android_image.h
@@ -12,6 +12,8 @@ 
 #ifndef _ANDROID_IMAGE_H_
 #define _ANDROID_IMAGE_H_
 
+#include <linux/types.h>
+
 typedef struct andr_img_hdr andr_img_hdr;
 
 #define ANDR_BOOT_MAGIC "ANDROID!"
diff --git a/include/linux/compat.h b/include/linux/compat.h
index a43e4d6698..b0ff6b91f0 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -111,6 +111,9 @@  static inline void kmem_cache_destroy(struct kmem_cache *cachep)
 
 #define PAGE_SIZE	4096
 
+/* to align the pointer to the (next) page boundary */
+#define PAGE_ALIGN(addr) ALIGN(addr, PAGE_SIZE)
+
 /* drivers/char/random.c */
 #define get_random_bytes(...)