From 63e424cec250374997bce1471d0c63dec0d71adc Mon Sep 17 00:00:00 2001 From: Furquan Shaikh Date: Thu, 18 Aug 2016 21:39:14 -0700 Subject: [PATCH] google/chromeec: Ensure data is ready before reading it Before reading the data provided by EC to the host, ensure that data ready flag is set. Otherwise, it could result in reading stale/incorrect data from the data buffer. BUG=chrome-os-partner:56395 BRANCH=None TEST=Verified that lidclose event is read correctly by host on reef. Change-Id: I88e345d64256af8325b3dbf670467d09f09420f0 Signed-off-by: Furquan Shaikh Reviewed-on: https://review.coreboot.org/16258 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin --- src/ec/google/chromeec/ec_lpc.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff --git a/src/ec/google/chromeec/ec_lpc.c b/src/ec/google/chromeec/ec_lpc.c index 06b506b059..51a6e53035 100644 --- a/src/ec/google/chromeec/ec_lpc.c +++ b/src/ec/google/chromeec/ec_lpc.c @@ -96,7 +96,7 @@ static inline u8 write_byte(u8 val, u16 port) return byte; } -static int google_chromeec_wait_ready(u16 port) +static int google_chromeec_status_check(u16 port, u8 mask, u8 cond) { u8 ec_status = read_byte(port); u32 time_count = 0; @@ -108,8 +108,7 @@ static int google_chromeec_wait_ready(u16 port) */ #define MAX_EC_TIMEOUT_US 1000000 - while (ec_status & - (EC_LPC_CMDR_PENDING | EC_LPC_CMDR_BUSY)) { + while ((ec_status & mask) != cond) { udelay(1); if (time_count++ == MAX_EC_TIMEOUT_US) return -1; @@ -118,6 +117,13 @@ static int google_chromeec_wait_ready(u16 port) return 0; } +static int google_chromeec_wait_ready(u16 port) +{ + return google_chromeec_status_check(port, + EC_LPC_CMDR_PENDING | + EC_LPC_CMDR_BUSY, 0); +} + #if CONFIG_EC_GOOGLE_CHROMEEC_ACPI_MEMMAP /* Read memmap data through ACPI port 66/62 */ static int read_memmap(u8 *data, u8 offset) @@ -481,6 +487,12 @@ struct chip_operations ec_google_chromeec_ops = { #endif /* __SMM__ */ +static int google_chromeec_data_ready(u16 port) +{ + return google_chromeec_status_check(port, EC_LPC_CMDR_DATA, + EC_LPC_CMDR_DATA); +} + u8 google_chromeec_get_event(void) { if (google_chromeec_wait_ready(EC_LPC_ADDR_ACPI_CMD)) { @@ -496,6 +508,11 @@ u8 google_chromeec_get_event(void) return 0; } + if (google_chromeec_data_ready(EC_LPC_ADDR_ACPI_CMD)) { + printk(BIOS_ERR, "Timeout waiting for data ready!\n"); + return 0; + } + /* Event (or 0 if none) is returned directly in the data byte */ return read_byte(EC_LPC_ADDR_ACPI_DATA); }