[PATCH 1/2] bootcount: add bootcount flash driver

[Arnaud Ferraris]

In order to save the bootcounter on raw flash device, this commit
introduces a new bootcount driver, enabled using the
CONFIG_BOOTCOUNT_FLASH option.

The bootcounter is stored at address CONFIG_SYS_BOOTCOUNT_FLASH_ADDR
(absolute address, can also be computed from
CONFIG_SYS_BOOTCOUNT_FLASH_OFFSET), and it uses a data structure
providing several useful enhancements:
 - a `flags` field, used to check whether the bootcounter should be
   written to flash (similar to the `upgrade_available` environment
   variable)
 - a `crc` field to ensure integrity of the structure, which will be
   used later on when adding redundancy support
 - a `data` field, which can be used to store and pass user data
   between u-boot and the OS (e.g boot partition selection)

Signed-off-by: Arnaud Ferraris <arnaud.ferraris at collabora.com>
---

 drivers/bootcount/Kconfig           | 14 ++++++
 drivers/bootcount/Makefile          |  1 +
 drivers/bootcount/bootcount_flash.c | 78 +++++++++++++++++++++++++++++
 include/bootcount.h                 | 12 +++++
 scripts/config_whitelist.txt        |  2 +
 5 files changed, 107 insertions(+)
 create mode 100644 drivers/bootcount/bootcount_flash.c

diff --git a/drivers/bootcount/Kconfig b/drivers/bootcount/Kconfig
index 0e506c9ea2..94de3f5ef8 100644
--- a/drivers/bootcount/Kconfig
+++ b/drivers/bootcount/Kconfig
@@ -66,6 +66,20 @@ config BOOTCOUNT_I2C
 	  CONFIG_SYS_BOOTCOUNT_ADDR = i2c addr which is used for
 	                              the bootcounter.
 
+config BOOTCOUNT_FLASH
+	bool "Boot counter on flash device"
+	help
+	  Store the bootcounter on raw flash. The bootcounter will be stored
+	  as a structure using one flash sector, and will only be written when
+	  a specific flag is set in the structure. Additionnally, this driver
+	  relies on one of the following to be defined:
+
+	  CONFIG_SYS_BOOTCOUNT_FLASH_ADDR = address used for storing the
+	                                    bootcounter on flash.
+	    or
+	  CONFIG_SYS_BOOTCOUNT_FLASH_OFFSET = bootcounter offset on flash
+	                                      (relative to SYS_FLASH_BASE).
+
 config BOOTCOUNT_AT91
 	bool "Boot counter for Atmel AT91SAM9XE"
 	depends on AT91SAM9XE
diff --git a/drivers/bootcount/Makefile b/drivers/bootcount/Makefile
index 73ccfb5a08..bddcd136f3 100644
--- a/drivers/bootcount/Makefile
+++ b/drivers/bootcount/Makefile
@@ -7,6 +7,7 @@ obj-$(CONFIG_BOOTCOUNT_RAM)	+= bootcount_ram.o
 obj-$(CONFIG_BOOTCOUNT_ENV)	+= bootcount_env.o
 obj-$(CONFIG_BOOTCOUNT_I2C)	+= bootcount_i2c.o
 obj-$(CONFIG_BOOTCOUNT_EXT)	+= bootcount_ext.o
+obj-$(CONFIG_BOOTCOUNT_FLASH)	+= bootcount_flash.o
 
 obj-$(CONFIG_DM_BOOTCOUNT)      += bootcount-uclass.o
 obj-$(CONFIG_DM_BOOTCOUNT_RTC)  += rtc.o
diff --git a/drivers/bootcount/bootcount_flash.c b/drivers/bootcount/bootcount_flash.c
new file mode 100644
index 0000000000..1222bb4ae0
--- /dev/null
+++ b/drivers/bootcount/bootcount_flash.c
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2020 Collabora Ltd. All rights reserved.
+ */
+
+#include <bootcount.h>
+#include <common.h>
+#include <asm/io.h>
+#include <u-boot/crc.h>
+#include <flash.h>
+
+#ifndef CONFIG_SYS_BOOTCOUNT_FLASH_ADDR
+#  ifdef CONFIG_SYS_BOOTCOUNT_FLASH_OFFSET
+#    define CONFIG_SYS_BOOTCOUNT_FLASH_ADDR	\
+		(CONFIG_SYS_FLASH_BASE + CONFIG_SYS_BOOTCOUNT_FLASH_OFFSET)
+#  else
+#    error "Either CONFIG_SYS_BOOTCOUNT_FLASH_ADDR or " \
+	   "CONFIG_SYS_BOOTCOUNT_FLASH_OFFSET should be defined!"
+#  endif
+#endif
+
+#define BOOTCOUNT_CRC_SIZE	(sizeof(*bootcount) - sizeof(bootcount->crc))
+
+static struct bootcount *bootcount = (void *)CONFIG_SYS_BOOTCOUNT_ADDR;
+static ulong bc_flash = CONFIG_SYS_BOOTCOUNT_FLASH_ADDR;
+static ulong bc_flash_end =
+	CONFIG_SYS_BOOTCOUNT_FLASH_ADDR + CONFIG_SYS_FLASH_SECT_SIZE - 1;
+
+static void bootcount_write(void)
+{
+	if (flash_sect_protect(0, bc_flash, bc_flash_end))
+		return;
+
+	puts("Erasing Flash...\n");
+	if (flash_sect_erase(bc_flash, bc_flash_end))
+		return;
+
+	puts("Writing bootcount to Flash...\n");
+	if (flash_write((char *)bootcount, bc_flash, sizeof(*bootcount)))
+		return;
+
+	flash_sect_protect(1, bc_flash, bc_flash_end);
+}
+
+static void bootcount_init(void)
+{
+	memset(bootcount, 0, sizeof(*bootcount));
+	bootcount->magic = CONFIG_SYS_BOOTCOUNT_MAGIC;
+	bootcount->crc = crc32(0, (uchar *)bootcount, BOOTCOUNT_CRC_SIZE);
+	bootcount_write();
+}
+
+void bootcount_store(ulong a)
+{
+	bootcount->count = a;
+	bootcount->crc = crc32(0, (uchar *)bootcount, BOOTCOUNT_CRC_SIZE);
+	if (bootcount->flags & BOOTCOUNT_FLAGS_UPDATE)
+		bootcount_write();
+}
+
+ulong bootcount_load(void)
+{
+	static int initialized;
+	u32 crc;
+
+	if (!initialized) {
+		memcpy(bootcount, (void *)bc_flash, sizeof(*bootcount));
+		initialized = 1;
+	}
+
+	crc = crc32(0, (uchar *)bootcount, BOOTCOUNT_CRC_SIZE);
+	if (bootcount->magic != CONFIG_SYS_BOOTCOUNT_MAGIC ||
+	    bootcount->crc != crc) {
+		bootcount_init();
+	}
+
+	return bootcount->count;
+}
diff --git a/include/bootcount.h b/include/bootcount.h
index cd30403984..5698bd3239 100644
--- a/include/bootcount.h
+++ b/include/bootcount.h
@@ -79,6 +79,18 @@ ulong bootcount_load(void);
 # endif
 #endif
 
+#ifdef CONFIG_BOOTCOUNT_FLASH
+struct bootcount {
+	u32 magic;
+	u32 count;
+	u32 flags;
+	u32 data;
+	u32 crc;
+};
+
+#define BOOTCOUNT_FLAGS_UPDATE	0x1
+#endif
+
 #ifdef CONFIG_SYS_BOOTCOUNT_LE
 static inline void raw_bootcount_store(volatile u32 *addr, u32 data)
 {
diff --git a/scripts/config_whitelist.txt b/scripts/config_whitelist.txt
index 6908431d03..672483f040 100644
--- a/scripts/config_whitelist.txt
+++ b/scripts/config_whitelist.txt
@@ -1829,6 +1829,8 @@ CONFIG_SYS_BOARD_NAME
 CONFIG_SYS_BOARD_OMAP3_HA
 CONFIG_SYS_BOOK3E_HV
 CONFIG_SYS_BOOTCOUNT_BE
+CONFIG_SYS_BOOTCOUNT_FLASH_ADDR
+CONFIG_SYS_BOOTCOUNT_FLASH_OFFSET
 CONFIG_SYS_BOOTCOUNT_LE
 CONFIG_SYS_BOOTFILE_PREFIX
 CONFIG_SYS_BOOTMAPSZ
-- 
2.26.1