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mb/opencellular/elgon: Enable write protection

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* Verify the flash write protection on each boot
* Program non-volatile write protection on first boot

Tested using I715791b8ae5d1db1ef587321ae5c9daa10eb7dbc.

The bootblock is write-protected as long as the #WP pin is asserted low:
* Reprogramming of the status register fails.
* Trying to write to WP_RO region fails.

Programming the WP_RO is only possible if #WP pin is high.

Change-Id: I6a940c69ecb1dfd9704b2101c263570bebc5540e
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/29532
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
This commit is contained in:
Patrick Rudolph
2018-11-07 15:24:37 +01:00
committed by Philipp Deppenwiese
parent e736015fff
commit fb444b0d20
1 changed files with 44 additions and 1 deletions
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45
src/mainboard/opencellular/elgon/bootblock.c
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@@ -18,6 +18,9 @@
#include <soc/spi.h>
#include <soc/uart.h>
#include <soc/gpio.h>
#include <spi_flash.h>
#include <console/console.h>
#include <fmap.h>
#include "mainboard.h"
void bootblock_mainboard_early_init(void)
@@ -49,8 +52,48 @@ static void configure_spi_flash(void)
gpio_output(ELGON_GPIO_SPI_MUX, 1);
}
/**
* Handle flash write protection.
* This code verifies the write-protection on each boot.
* Enabling the write protection does only run on the first boot.
* An error is fatal as it breaks the Chain Of Trust.
*/
static void protect_ro_rgn_spi_flash(void)
{
const struct spi_flash *flash = boot_device_spi_flash();
const char *fmapname = "WP_RO";
struct region ro_rgn;
if (fmap_locate_area(fmapname, &ro_rgn)) {
printk(BIOS_ERR, "%s: No %s FMAP section.\n", __func__,
fmapname);
die("Can't verify flash protections!");
}
u8 reg8 = 0;
spi_flash_status(flash, &reg8);
/* Check if SRP0 is set and RO region is protected */
if (!(reg8 & 0x80) ||
spi_flash_is_write_protected(flash, &ro_rgn) != 1) {
printk(BIOS_WARNING, "%s: FMAP section %s is not write-protected\n",
__func__, fmapname);
/*
* Need to protect flash region :
* WP_RO read only and use /WP pin
* non-volatile programming
*/
if (spi_flash_set_write_protected(flash, &ro_rgn, 1,
SPI_WRITE_PROTECTION_PIN) != 0)
die("Failed to write-protect WP_RO region!");
}
printk(BIOS_INFO, "%s: FMAP section %s is write-protected\n",
__func__, fmapname);
}
void bootblock_mainboard_init(void)
{
configure_spi_flash();
// FIXME: Check SPI flash WP bits
protect_ro_rgn_spi_flash();
}