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writeprotect.c: skip unnecessary writes

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* Don't write register because of RO and OTP bits.
* Skip the write of RW bits if register state wouldn't change by it.

Change-Id: I81d2d3fc0a103ee00ced78838d77fe33a9d3056a
Signed-off-by: Sergii Dmytruk <sergii.dmytruk@3mdeb.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/66754
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Edward O'Callaghan <quasisec@chromium.org>
Reviewed-by: Nikolai Artemiev <nartemiev@google.com>
This commit is contained in:
Sergii Dmytruk 2022-08-14 16:51:46 +03:00 committed by Anastasia Klimchuk
parent 4df64d93a0
commit 6d475ec4ab
1 changed files with 28 additions and 17 deletions
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45
writeprotect.c
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@ -110,12 +110,16 @@ static enum flashrom_wp_result read_wp_bits(struct wp_bits *bits, struct flashct
/** Helper function for write_wp_bits(). */
static void set_reg_bit(
uint8_t *reg_values, uint8_t *write_masks,
uint8_t *reg_values, uint8_t *bit_masks, uint8_t *write_masks,
struct reg_bit_info bit, uint8_t value)
{
if (bit.reg != INVALID_REG) {
reg_values[bit.reg] |= value << bit.bit_index;
write_masks[bit.reg] |= 1 << bit.bit_index;
bit_masks[bit.reg] |= 1 << bit.bit_index;
/* Avoid RO and OTP bits causing a register update */
if (bit.writability == RW)
write_masks[bit.reg] |= 1 << bit.bit_index;
}
}
@ -125,22 +129,23 @@ static enum flashrom_wp_result write_wp_bits(struct flashctx *flash, struct wp_b
size_t i;
const struct reg_bit_map *reg_bits = &flash->chip->reg_bits;
/* Convert wp_bits to register values and write masks */
/* Convert wp_bits to register values and masks */
uint8_t reg_values[MAX_REGISTERS] = {0};
uint8_t write_masks[MAX_REGISTERS] = {0};
uint8_t bit_masks[MAX_REGISTERS] = {0}; /* masks of valid bits */
uint8_t write_masks[MAX_REGISTERS] = {0}; /* masks of written bits */
for (i = 0; i < bits.bp_bit_count; i++)
set_reg_bit(reg_values, write_masks, reg_bits->bp[i], bits.bp[i]);
set_reg_bit(reg_values, bit_masks, write_masks, reg_bits->bp[i], bits.bp[i]);
set_reg_bit(reg_values, write_masks, reg_bits->tb, bits.tb);
set_reg_bit(reg_values, write_masks, reg_bits->sec, bits.sec);
set_reg_bit(reg_values, write_masks, reg_bits->cmp, bits.cmp);
set_reg_bit(reg_values, write_masks, reg_bits->srp, bits.srp);
set_reg_bit(reg_values, write_masks, reg_bits->srl, bits.srl);
set_reg_bit(reg_values, bit_masks, write_masks, reg_bits->tb, bits.tb);
set_reg_bit(reg_values, bit_masks, write_masks, reg_bits->sec, bits.sec);
set_reg_bit(reg_values, bit_masks, write_masks, reg_bits->cmp, bits.cmp);
set_reg_bit(reg_values, bit_masks, write_masks, reg_bits->srp, bits.srp);
set_reg_bit(reg_values, bit_masks, write_masks, reg_bits->srl, bits.srl);
/* Note: always setting WPS bit to zero until its fully supported. */
set_reg_bit(reg_values, write_masks, reg_bits->wps, 0);
set_reg_bit(reg_values, bit_masks, write_masks, reg_bits->wps, 0);
/* Write each register */
/* Write each register whose value was updated */
for (enum flash_reg reg = STATUS1; reg < MAX_REGISTERS; reg++) {
if (!write_masks[reg])
continue;
@ -149,16 +154,22 @@ static enum flashrom_wp_result write_wp_bits(struct flashctx *flash, struct wp_b
if (wp_read_register(flash, reg, &value))
return FLASHROM_WP_ERR_READ_FAILED;
value = (value & ~write_masks[reg]) | (reg_values[reg] & write_masks[reg]);
/* Skip unnecessary register writes */
uint8_t actual = value & write_masks[reg];
uint8_t expected = reg_values[reg] & write_masks[reg];
if (actual == expected)
continue;
value = (value & ~write_masks[reg]) | expected;
if (wp_write_register(flash, reg, value))
return FLASHROM_WP_ERR_WRITE_FAILED;
}
enum flashrom_wp_result ret = FLASHROM_WP_OK;
/* Verify each register */
/* Verify each register even if write to it was skipped */
for (enum flash_reg reg = STATUS1; reg < MAX_REGISTERS; reg++) {
if (!write_masks[reg])
if (!bit_masks[reg])
continue;
uint8_t value;
@ -166,8 +177,8 @@ static enum flashrom_wp_result write_wp_bits(struct flashctx *flash, struct wp_b
return FLASHROM_WP_ERR_READ_FAILED;
msg_cdbg2("%s: wp_verify reg:%u value:0x%x\n", __func__, reg, value);
uint8_t actual = value & write_masks[reg];
uint8_t expected = reg_values[reg] & write_masks[reg];
uint8_t actual = value & bit_masks[reg];
uint8_t expected = reg_values[reg] & bit_masks[reg];
if (actual != expected) {
msg_cdbg("%s: wp_verify failed: reg:%u actual:0x%x expected:0x%x\n",