smart battery: Fix mfgacc access function reading wrong number of bytes

`sb_read_mfgacc` currently uses `sb_read_string`. This function reads a
null-terminated string. However, the data that is being read is not a
null-terminated string. This is causing N-1 bytes to be read instead of
N bytes. This commit adds an `sb_read_sized_block` function that is used
instead. Only PARAM_SAFETY_STATUS and PARAM_OPERATION_STATUS are read
with `sb_read_mfgacc` and neither of these values are a string.

BUG=b:228589840
TEST=Ran i2ctrace to verify that right number of bytes are now being
read, tested with CL:3578293 to ensure no errors
BRANCH=guybrush

Change-Id: Iaedb4d28274bda8b6d1ee6d2021ebd04f83767f8
Signed-off-by: Robert Zieba <robertzieba@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3606146
Reviewed-by: Rob Barnes <robbarnes@google.com>
Reviewed-by: Diana Z <dzigterman@chromium.org>
Reviewed-by: Daisuke Nojiri <dnojiri@chromium.org>

1 files changed, 14 insertions, 1 deletions

diff --git a/include/battery_smart.h b/include/battery_smart.h
index b97d681223..9b373f7c8a 100644
--- a/include/battery_smart.h
+++ b/include/battery_smart.h
@@ -169,9 +169,22 @@
 /* Read from battery */
 int sb_read(int cmd, int *param);
 
-/* Read sequence from battery */
+/**
+ * Read null-terminated string from battery
+ * @param offset	Battery register to read from
+ * @param data		Buffer to hold the string
+ * @param len		Length of data buffer
+ */
 int sb_read_string(int offset, uint8_t *data, int len);
 
+/**
+ * Read sized block of data from battery
+ * @param offset	Battery register to read from
+ * @param data		Buffer to hold read data
+ * @param len		Length of data buffer
+ */
+int sb_read_sized_block(int offset, uint8_t *data, int len);
+
 /* Write to battery */
 int sb_write(int cmd, int param);