path: root/common/flash.c

/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/* Flash memory module for Chrome EC - common functions */

#include "common.h"
#include "console.h"
#include "flash.h"
#include "gpio.h"
#include "host_command.h"
#include "shared_mem.h"
#include "system.h"
#include "util.h"
#include "vboot_hash.h"

/*
 * Contents of erased flash, as a 32-bit value.  Most platforms erase flash
 * bits to 1.
 */
#ifndef CONFIG_FLASH_ERASED_VALUE32
#define CONFIG_FLASH_ERASED_VALUE32 (-1U)
#endif

/* Persistent protection state - emulates a SPI status register for flashrom */
struct persist_state {
	uint8_t version;            /* Version of this struct */
	uint8_t flags;              /* Lock flags (PERSIST_FLAG_*) */
	uint8_t reserved[2];        /* Reserved; set 0 */
};

#define PERSIST_STATE_VERSION 2  /* Expected persist_state.version */

/* Flags for persist_state.flags */
/* Protect persist state and RO firmware at boot */
#define PERSIST_FLAG_PROTECT_RO 0x02

/**
 * Get the physical memory address of a flash offset
 *
 * This is used for direct flash access. We assume that the flash is
 * contiguous from this start address through to the end of the usable
 * flash.
 *
 * @param offset	Flash offset to get address of
 * @param dataptrp	Returns pointer to memory address of flash offset
 * @return pointer to flash memory offset, if ok, else NULL
 */
static const char *flash_physical_dataptr(int offset)
{
	return (char *)((uintptr_t)CONFIG_FLASH_BASE + offset);
}

/**
 * Read persistent state into pstate.
 *
 * @param pstate	Destination for persistent state
 */
static void flash_read_pstate(struct persist_state *pstate)
{
	memcpy(pstate, flash_physical_dataptr(PSTATE_OFFSET), sizeof(*pstate));

	/* Sanity-check data and initialize if necessary */
	if (pstate->version != PERSIST_STATE_VERSION) {
		memset(pstate, 0, sizeof(*pstate));
		pstate->version = PERSIST_STATE_VERSION;
	}
}

/**
 * Write persistent state from pstate, erasing if necessary.
 *
 * @param pstate	Source persistent state
 * @return EC_SUCCESS, or nonzero if error.
 */
static int flash_write_pstate(const struct persist_state *pstate)
{
	struct persist_state current_pstate;
	int rv;

	/* Check if pstate has actually changed */
	flash_read_pstate(&current_pstate);
	if (!memcmp(&current_pstate, pstate, sizeof(*pstate)))
		return EC_SUCCESS;

	/* Erase pstate */
	rv = flash_physical_erase(PSTATE_OFFSET, PSTATE_SIZE);
	if (rv)
		return rv;

	/*
	 * Note that if we lose power in here, we'll lose the pstate contents.
	 * That's ok, because it's only possible to write the pstate before
	 * it's protected.
	 */

	/* Rewrite the data */
	return flash_physical_write(PSTATE_OFFSET, sizeof(*pstate),
				    (const char *)pstate);
}

int flash_dataptr(int offset, int size_req, int align, const char **ptrp)
{
	if (offset < 0 || size_req < 0 ||
			offset + size_req > CONFIG_FLASH_SIZE ||
			(offset | size_req) & (align - 1))
		return -1;  /* Invalid range */
	if (ptrp)
		*ptrp = flash_physical_dataptr(offset);

	return CONFIG_FLASH_SIZE - offset;
}

int flash_is_erased(uint32_t offset, int size)
{
	const uint32_t *ptr;

	if (flash_dataptr(offset, size, sizeof(uint32_t),
			  (const char **)&ptr) < 0)
		return 0;

	for (size /= sizeof(uint32_t); size > 0; size -= 4, ptr++)
		if (*ptr != CONFIG_FLASH_ERASED_VALUE32)
			return 0;

	return 1;
}

int flash_write(int offset, int size, const char *data)
{
	if (flash_dataptr(offset, size, CONFIG_FLASH_WRITE_SIZE, NULL) < 0)
		return EC_ERROR_INVAL;  /* Invalid range */

#ifdef CONFIG_VBOOT_HASH
	vboot_hash_invalidate(offset, size);
#endif

	return flash_physical_write(offset, size, data);
}

int flash_erase(int offset, int size)
{
	if (flash_dataptr(offset, size, CONFIG_FLASH_ERASE_SIZE, NULL) < 0)
		return EC_ERROR_INVAL;  /* Invalid range */

#ifdef CONFIG_VBOOT_HASH
	vboot_hash_invalidate(offset, size);
#endif

	return flash_physical_erase(offset, size);
}

int flash_protect_ro_at_boot(int enable)
{
	struct persist_state pstate;
	int new_flags = enable ? PERSIST_FLAG_PROTECT_RO : 0;

	/* Read the current persist state from flash */
	flash_read_pstate(&pstate);

	if (pstate.flags != new_flags) {
		/* Need to update pstate */
		int rv;

		/* Fail if write protect block is already locked */
		if (flash_physical_get_protect(PSTATE_BANK))
			return EC_ERROR_ACCESS_DENIED;

		/* Set the new flag */
		pstate.flags = new_flags;

		/* Write the state back to flash */
		rv = flash_write_pstate(&pstate);
		if (rv)
			return rv;
	}

#ifdef CONFIG_FLASH_PROTECT_NEXT_BOOT
	/*
	 * Try updating at-boot protection state, if on a platform where write
	 * protection only changes after a reboot.  Otherwise we wouldn't
	 * update it until after the next reboot, and we'd need to reboot
	 * again.  Ignore errors, because the protection registers might
	 * already be locked this boot, and we'll still apply the correct state
	 * again on the next boot.
	 *
	 * This assumes PSTATE immediately follows RO, which it does on
	 * all STM32 platforms (which are the only ones with this config).
	 */
	flash_physical_protect_ro_at_boot(new_flags);
#endif

	return EC_SUCCESS;
}

uint32_t flash_get_protect(void)
{
	struct persist_state pstate;
	uint32_t flags = 0;
	int not_protected[2] = {0};
	int i;

	/* Read write protect GPIO */
#ifdef CONFIG_WP_ACTIVE_HIGH
	if (gpio_get_level(GPIO_WP))
		flags |= EC_FLASH_PROTECT_GPIO_ASSERTED;
#else
	if (!gpio_get_level(GPIO_WP_L))
		flags |= EC_FLASH_PROTECT_GPIO_ASSERTED;
#endif

	/* Read persistent state of RO-at-boot flag */
	flash_read_pstate(&pstate);
	if (pstate.flags & PERSIST_FLAG_PROTECT_RO)
		flags |= EC_FLASH_PROTECT_RO_AT_BOOT;

	/* Scan flash protection */
	for (i = 0; i < PHYSICAL_BANKS; i++) {
		/*
		 * Is this bank part of RO?  Needs to handle PSTATE not
		 * immediately following RO code, since it doesn't on link.
		 */
		int is_ro = ((i >= RO_BANK_OFFSET &&
			      i < RO_BANK_OFFSET + RO_BANK_COUNT) ||
			     (i >= PSTATE_BANK &&
			      i < PSTATE_BANK + PSTATE_BANK_COUNT)) ? 1 : 0;
		int bank_flag = (is_ro ? EC_FLASH_PROTECT_RO_NOW :
				 EC_FLASH_PROTECT_ALL_NOW);

		if (flash_physical_get_protect(i)) {
			/* At least one bank in the region is protected */
			flags |= bank_flag;
			if (not_protected[is_ro])
				flags |= EC_FLASH_PROTECT_ERROR_INCONSISTENT;
		} else {
			/* At least one bank in the region is NOT protected */
			not_protected[is_ro] = 1;
			if (flags & bank_flag)
				flags |= EC_FLASH_PROTECT_ERROR_INCONSISTENT;
		}
	}

	/*
	 * If the RW banks are protected but the RO banks aren't, that's
	 * inconsistent.
	 *
	 * Note that we check this before adding in the physical flags below,
	 * since some chips can also protect ALL_NOW for the current boot by
	 * locking up the flash program-erase registers.
	 */
	if ((flags & EC_FLASH_PROTECT_ALL_NOW) &&
	    !(flags & EC_FLASH_PROTECT_RO_NOW))
		flags |= EC_FLASH_PROTECT_ERROR_INCONSISTENT;

	/* Add in flags from physical layer */
	return flags | flash_physical_get_protect_flags();
}

int flash_set_protect(uint32_t mask, uint32_t flags)
{
	int retval = EC_SUCCESS;
	int rv;

	/*
	 * Process flags we can set.  Track the most recent error, but process
	 * all flags before returning.
	 */
	if (mask & EC_FLASH_PROTECT_RO_AT_BOOT) {
		rv = flash_protect_ro_at_boot(
			      flags & EC_FLASH_PROTECT_RO_AT_BOOT);
		if (rv)
			retval = rv;
	}

	/*
	 * All subsequent flags only work if write protect is enabled (that is,
	 * hardware WP flag) *and* RO is protected at boot (software WP flag).
	 */
	if ((~flash_get_protect()) & (EC_FLASH_PROTECT_GPIO_ASSERTED |
				      EC_FLASH_PROTECT_RO_AT_BOOT))
		return retval;

	if ((mask & EC_FLASH_PROTECT_RO_NOW) &&
	    (flags & EC_FLASH_PROTECT_RO_NOW)) {
		rv = flash_physical_protect_now(0);
		if (rv)
			retval = rv;
	}

	if ((mask & EC_FLASH_PROTECT_ALL_NOW) &&
	    (flags & EC_FLASH_PROTECT_ALL_NOW)) {
		rv = flash_physical_protect_now(1);
		if (rv)
			retval = rv;
	}

	return retval;
}

/*****************************************************************************/
/* Console commands */

/**
 * Parse offset and size from command line argv[shift] and argv[shift+1]
 *
 * Default values: If argc<=shift, leaves offset unchanged, returning error if
 * *offset<0.  If argc<shift+1, leaves size unchanged, returning error if
 * *size<0.
 */
static int parse_offset_size(int argc, char **argv, int shift,
			     int *offset, int *size)
{
	char *e;
	int i;

	if (argc > shift) {
		i = (uint32_t)strtoi(argv[shift], &e, 0);
		if (*e)
			return EC_ERROR_PARAM1;
		*offset = i;
	} else if (*offset < 0)
		return EC_ERROR_PARAM_COUNT;

	if (argc > shift + 1) {
		i = (uint32_t)strtoi(argv[shift + 1], &e, 0);
		if (*e)
			return EC_ERROR_PARAM2;
		*size = i;
	} else if (*size < 0)
		return EC_ERROR_PARAM_COUNT;

	return EC_SUCCESS;
}

static int command_flash_info(int argc, char **argv)
{
	int i;

	ccprintf("Physical:%4d KB\n", CONFIG_FLASH_PHYSICAL_SIZE / 1024);
	ccprintf("Usable:  %4d KB\n", CONFIG_FLASH_SIZE / 1024);
	ccprintf("Write:   %4d B (ideal %d B)\n", CONFIG_FLASH_WRITE_SIZE,
		 CONFIG_FLASH_WRITE_IDEAL_SIZE);
	ccprintf("Erase:   %4d B (to %d-bits)\n", CONFIG_FLASH_ERASE_SIZE,
		 CONFIG_FLASH_ERASED_VALUE32 ? 1 : 0);
	ccprintf("Protect: %4d B\n", CONFIG_FLASH_BANK_SIZE);

	i = flash_get_protect();
	ccprintf("Flags:  ");
	if (i & EC_FLASH_PROTECT_GPIO_ASSERTED)
		ccputs(" wp_gpio_asserted");
	if (i & EC_FLASH_PROTECT_RO_AT_BOOT)
		ccputs(" ro_at_boot");
	if (i & EC_FLASH_PROTECT_ALL_AT_BOOT)
		ccputs(" all_at_boot");
	if (i & EC_FLASH_PROTECT_RO_NOW)
		ccputs(" ro_now");
	if (i & EC_FLASH_PROTECT_ALL_NOW)
		ccputs(" all_now");
	if (i & EC_FLASH_PROTECT_ERROR_STUCK)
		ccputs(" STUCK");
	if (i & EC_FLASH_PROTECT_ERROR_INCONSISTENT)
		ccputs(" INCONSISTENT");
	ccputs("\n");

	ccputs("Protected now:");
	for (i = 0; i < CONFIG_FLASH_PHYSICAL_SIZE / CONFIG_FLASH_BANK_SIZE;
	     i++) {
		if (!(i & 31))
			ccputs("\n    ");
		else if (!(i & 7))
			ccputs(" ");
		ccputs(flash_physical_get_protect(i) ? "Y" : ".");
	}
	ccputs("\n");

	return EC_SUCCESS;
}
DECLARE_CONSOLE_COMMAND(flashinfo, command_flash_info,
			NULL,
			"Print flash info",
			NULL);

static int command_flash_erase(int argc, char **argv)
{
	int offset = -1;
	int size = CONFIG_FLASH_ERASE_SIZE;
	int rv;

	if (flash_get_protect() & EC_FLASH_PROTECT_ALL_NOW)
		return EC_ERROR_ACCESS_DENIED;

	rv = parse_offset_size(argc, argv, 1, &offset, &size);
	if (rv)
		return rv;

	ccprintf("Erasing %d bytes at 0x%x...\n", size, offset, offset);
	return flash_erase(offset, size);
}
DECLARE_CONSOLE_COMMAND(flasherase, command_flash_erase,
			"offset [size]",
			"Erase flash",
			NULL);

static int command_flash_write(int argc, char **argv)
{
	int offset = -1;
	int size = CONFIG_FLASH_ERASE_SIZE;
	int rv;
	char *data;
	int i;

	if (flash_get_protect() & EC_FLASH_PROTECT_ALL_NOW)
		return EC_ERROR_ACCESS_DENIED;

	rv = parse_offset_size(argc, argv, 1, &offset, &size);
	if (rv)
		return rv;

	if (size > shared_mem_size())
		size = shared_mem_size();

	/* Acquire the shared memory buffer */
	rv = shared_mem_acquire(size, &data);
	if (rv) {
		ccputs("Can't get shared mem\n");
		return rv;
	}

	/* Fill the data buffer with a pattern */
	for (i = 0; i < size; i++)
		data[i] = i;

	ccprintf("Writing %d bytes to 0x%x...\n",
		 size, offset, offset);
	rv = flash_write(offset, size, data);

	/* Free the buffer */
	shared_mem_release(data);

	return rv;
}
DECLARE_CONSOLE_COMMAND(flashwrite, command_flash_write,
			"offset [size]",
			"Write pattern to flash",
			NULL);

static int command_flash_wp(int argc, char **argv)
{
	if (argc < 2)
		return EC_ERROR_PARAM_COUNT;

	if (!strcasecmp(argv[1], "enable"))
		return flash_set_protect(EC_FLASH_PROTECT_RO_AT_BOOT, -1);
	else if (!strcasecmp(argv[1], "disable"))
		return flash_set_protect(EC_FLASH_PROTECT_RO_AT_BOOT, 0);
	else if (!strcasecmp(argv[1], "now"))
		return flash_set_protect(EC_FLASH_PROTECT_ALL_NOW, -1);
	else if (!strcasecmp(argv[1], "rw"))
		return flash_set_protect(EC_FLASH_PROTECT_ALL_AT_BOOT, -1);
	else if (!strcasecmp(argv[1], "norw"))
		return flash_set_protect(EC_FLASH_PROTECT_ALL_AT_BOOT, 0);
	else
		return EC_ERROR_PARAM1;
}
DECLARE_CONSOLE_COMMAND(flashwp, command_flash_wp,
			"<enable | disable | now | rw | norw>",
			"Modify flash write protect",
			NULL);

/*****************************************************************************/
/* Host commands */

static int flash_command_get_info(struct host_cmd_handler_args *args)
{
	struct ec_response_flash_info_1 *r = args->response;

	r->flash_size = CONFIG_FLASH_SIZE;
	r->write_block_size = CONFIG_FLASH_WRITE_SIZE;
	r->erase_block_size = CONFIG_FLASH_ERASE_SIZE;
	r->protect_block_size = CONFIG_FLASH_BANK_SIZE;

	if (args->version == 0) {
		/* Only version 0 fields returned */
		args->response_size = sizeof(struct ec_response_flash_info);
	} else {
		/* Fill in full version 1 struct */

		/*
		 * Compute the ideal amount of data for the host to send us,
		 * based on the maximum response size and the ideal write size.
		 */
		r->write_ideal_size =
			(args->response_max -
			 sizeof(struct ec_params_flash_write)) &
			~(CONFIG_FLASH_WRITE_IDEAL_SIZE - 1);
		/*
		 * If we can't get at least one ideal block, then just want
		 * as high a multiple of the minimum write size as possible.
		 */
		if (!r->write_ideal_size)
			r->write_ideal_size =
				(args->response_max -
				 sizeof(struct ec_params_flash_write)) &
				~(CONFIG_FLASH_WRITE_SIZE - 1);

		r->flags = 0;

#if (CONFIG_FLASH_ERASED_VALUE32 == 0)
		r->flags |= EC_FLASH_INFO_ERASE_TO_0;
#endif

		args->response_size = sizeof(*r);
	}
	return EC_RES_SUCCESS;
}
DECLARE_HOST_COMMAND(EC_CMD_FLASH_INFO,
		     flash_command_get_info,
		     EC_VER_MASK(0) | EC_VER_MASK(1));

static int flash_command_read(struct host_cmd_handler_args *args)
{
	const struct ec_params_flash_read *p = args->params;
	const char *src;

	if (flash_dataptr(p->offset, p->size, 1, &src) < 0)
		return EC_RES_ERROR;

	if (p->size > args->response_max)
		return EC_RES_OVERFLOW;

	memcpy(args->response, src, p->size);
	args->response_size = p->size;

	return EC_RES_SUCCESS;
}
DECLARE_HOST_COMMAND(EC_CMD_FLASH_READ,
		     flash_command_read,
		     EC_VER_MASK(0));

/**
 * Flash write command
 *
 * Version 0 and 1 are equivalent from the EC-side; the only difference is
 * that the host can only send 64 bytes of data at a time in version 0.
 */
static int flash_command_write(struct host_cmd_handler_args *args)
{
	const struct ec_params_flash_write *p = args->params;

	if (flash_get_protect() & EC_FLASH_PROTECT_ALL_NOW)
		return EC_RES_ACCESS_DENIED;

	if (p->size + sizeof(*p) > args->params_size)
		return EC_RES_INVALID_PARAM;

	if (system_unsafe_to_overwrite(p->offset, p->size))
		return EC_RES_ACCESS_DENIED;

	if (flash_write(p->offset, p->size, (const uint8_t *)(p + 1)))
		return EC_RES_ERROR;

	return EC_RES_SUCCESS;
}
DECLARE_HOST_COMMAND(EC_CMD_FLASH_WRITE,
		     flash_command_write,
		     EC_VER_MASK(0) | EC_VER_MASK(EC_VER_FLASH_WRITE));

static int flash_command_erase(struct host_cmd_handler_args *args)
{
	const struct ec_params_flash_erase *p = args->params;

	if (flash_get_protect() & EC_FLASH_PROTECT_ALL_NOW)
		return EC_RES_ACCESS_DENIED;

	if (system_unsafe_to_overwrite(p->offset, p->size))
		return EC_RES_ACCESS_DENIED;

	/* Indicate that we might be a while */
#if defined(HAS_TASK_HOSTCMD) && defined(CONFIG_HOST_COMMAND_STATUS)
	args->result = EC_RES_IN_PROGRESS;
	host_send_response(args);
#endif
	if (flash_erase(p->offset, p->size))
		return EC_RES_ERROR;

	return EC_RES_SUCCESS;
}
DECLARE_HOST_COMMAND(EC_CMD_FLASH_ERASE,
		     flash_command_erase,
		     EC_VER_MASK(0));

static int flash_command_protect(struct host_cmd_handler_args *args)
{
	const struct ec_params_flash_protect *p = args->params;
	struct ec_response_flash_protect *r = args->response;

	/*
	 * Handle requesting new flags.  Note that we ignore the return code
	 * from flash_set_protect(), since errors will be visible to the caller
	 * via the flags in the response.  (If we returned error, the caller
	 * wouldn't get the response.)
	 */
	if (p->mask)
		flash_set_protect(p->mask, p->flags);

	/*
	 * Retrieve the current flags.  The caller can use this to determine
	 * which of the requested flags could be set.  This is cleaner than
	 * simply returning error, because it provides information to the
	 * caller about the actual result.
	 */
	r->flags = flash_get_protect();

	/* Indicate which flags are valid on this platform */
	r->valid_flags =
		EC_FLASH_PROTECT_GPIO_ASSERTED |
		EC_FLASH_PROTECT_ERROR_STUCK |
		EC_FLASH_PROTECT_RO_AT_BOOT |
		EC_FLASH_PROTECT_RO_NOW |
		EC_FLASH_PROTECT_ALL_NOW |
		EC_FLASH_PROTECT_ERROR_INCONSISTENT;
	r->writable_flags = 0;

	/* If RO protection isn't enabled, its at-boot state can be changed. */
	if (!(r->flags & EC_FLASH_PROTECT_RO_NOW))
		r->writable_flags |= EC_FLASH_PROTECT_RO_AT_BOOT;

	/*
	 * If entire flash isn't protected at this boot, it can be enabled if
	 * the WP GPIO is asserted.
	 */
	if (!(r->flags & EC_FLASH_PROTECT_ALL_NOW) &&
	    (r->flags & EC_FLASH_PROTECT_GPIO_ASSERTED))
		r->writable_flags |= EC_FLASH_PROTECT_ALL_NOW;

	args->response_size = sizeof(*r);

	return EC_RES_SUCCESS;
}

/*
 * TODO(crbug.com/239197) : Adding both versions to the version mask is a
 * temporary workaround for a problem in the cros_ec driver. Drop
 * EC_VER_MASK(0) once cros_ec driver can send the correct version.
 */
DECLARE_HOST_COMMAND(EC_CMD_FLASH_PROTECT,
		     flash_command_protect,
		     EC_VER_MASK(0) | EC_VER_MASK(1));

static int flash_command_region_info(struct host_cmd_handler_args *args)
{
	const struct ec_params_flash_region_info *p = args->params;
	struct ec_response_flash_region_info *r = args->response;

	switch (p->region) {
	case EC_FLASH_REGION_RO:
		r->offset = CONFIG_FW_RO_OFF;
		r->size = CONFIG_FW_RO_SIZE;
		break;
	case EC_FLASH_REGION_RW:
		r->offset = CONFIG_FW_RW_OFF;
		r->size = CONFIG_FW_RW_SIZE;
		break;
	case EC_FLASH_REGION_WP_RO:
		r->offset = CONFIG_FW_WP_RO_OFF;
		r->size = CONFIG_FW_WP_RO_SIZE;
		break;
	default:
		return EC_RES_INVALID_PARAM;
	}

	args->response_size = sizeof(*r);
	return EC_RES_SUCCESS;
}
DECLARE_HOST_COMMAND(EC_CMD_FLASH_REGION_INFO,
		     flash_command_region_info,
		     EC_VER_MASK(EC_VER_FLASH_REGION_INFO));