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stm32: Don't use a stack buffer for i2c_read_string()

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We read a counted string (byte 0 = count, bytes 1 - count = chars) and
convert it to a null-terminated string.  Since both have a 1-byte
overhead, we can use the destination buffer instead of using a
stack-based buffer.

BUG=chrome-os-partner:23928
BRANCH=none (pit is affected, but battery console command isn't used on
       end user systems)
TEST=battery command shows correct strings (SDI / 4302D40 / LiP), and doesn't
     stack overflow.

Change-Id: Ic0f111cde2d57b41d6ce9287e0c771acc09a8869
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/176116
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
This commit is contained in:
Randall Spangler
2013-11-07 13:18:48 -08:00
committed by chrome-internal-fetch
parent 03de7bee72
commit bb9b335e31
2 changed files with 15 additions and 17 deletions
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15
chip/stm32/i2c-stm32f.c
View File

@@ -874,25 +874,24 @@ int i2c_read_string(int port, int slave_addr, int offset, uint8_t *data,
/*
* TODO(crosbug.com/p/23569): when i2c_xfer() supports start/stop bits,
* won't need a temp buffer, and this code can merge with the LM4
* implementation and move to i2c_common.c.
* merge this with the LM4 implementation and move to i2c_common.c.
*/
uint8_t buffer[SMBUS_MAX_BLOCK + 1];
if ((len <= 0) || (len > SMBUS_MAX_BLOCK))
return EC_ERROR_INVAL;
i2c_lock(port, 1);
/* Read the counted string into the output buffer */
reg = offset;
rv = i2c_xfer(port, slave_addr, &reg, 1, buffer, SMBUS_MAX_BLOCK + 1,
I2C_XFER_SINGLE);
rv = i2c_xfer(port, slave_addr, &reg, 1, data, len, I2C_XFER_SINGLE);
if (rv == EC_SUCCESS) {
/* Block length is the first byte of the returned buffer */
block_length = MIN(buffer[0], len - 1);
buffer[block_length + 1] = 0;
block_length = MIN(data[0], len - 1);
memcpy(data, buffer+1, block_length + 1);
/* Move data down, then null-terminate it */
memmove(data, data + 1, block_length);
data[block_length] = 0;
}
i2c_lock(port, 0);

17
chip/stm32/i2c-stm32l.c
View File

@@ -459,26 +459,25 @@ int i2c_read_string(int port, int slave_addr, int offset, uint8_t *data,
uint8_t reg, block_length;
/*
* TODO(crosbug.com/p/23569): When i2c_xfer() supports start/stop bits
* on all platforms, won't need a temp buffer, and this code can merge
* with the LM4 implementation and move to i2c_common.c.
* TODO(crosbug.com/p/23569): when i2c_xfer() supports start/stop bits,
* merge this with the LM4 implementation and move to i2c_common.c.
*/
uint8_t buffer[SMBUS_MAX_BLOCK + 1];
if ((len <= 0) || (len > SMBUS_MAX_BLOCK))
return EC_ERROR_INVAL;
i2c_lock(port, 1);
/* Read the counted string into the output buffer */
reg = offset;
rv = i2c_xfer(port, slave_addr, &reg, 1, buffer, SMBUS_MAX_BLOCK + 1,
I2C_XFER_SINGLE);
rv = i2c_xfer(port, slave_addr, &reg, 1, data, len, I2C_XFER_SINGLE);
if (rv == EC_SUCCESS) {
/* Block length is the first byte of the returned buffer */
block_length = MIN(buffer[0], len - 1);
buffer[block_length + 1] = 0;
block_length = MIN(data[0], len - 1);
memcpy(data, buffer+1, block_length + 1);
/* Move data down, then null-terminate it */
memmove(data, data + 1, block_length);
data[block_length] = 0;
}
i2c_lock(port, 0);