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

[Daniel Schwierzeck]

Am 22.04.20 um 12:46 schrieb 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);

Why don't you build this on top of the MTD layer to make it compatible
with all flash media types? Nowadays no one uses parallel NOR flash
devices anymore ;)

Also why don't you continously write new entries until the sector is
full? Erasing the sector on every boot kills the flash sector early.

> +}
> +
> +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
> 

-- 
- Daniel