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ec/google/chromeec: Add minimum delay between SPI CS assertions 

Some Chrome OS ECs require a small amount of time after a SPI
transaction to reset their controllers before they can service the next
CS assertion. The kernel and depthcharge have always enforced a 200us
minimum delay for this... coreboot should've done the same.

BRANCH=gru
BUG=chrome-os-partner:58046
TEST=Booted Kevin in recovery mode, confirmed that recovery events got
logged with correct timestamps in eventlog.

Change-Id: I32ec343f3293ac93729d3e6e2f43d7605a396cdb
Signed-off-by: Patrick Georgi <pgeorgi@chromium.org>
Original-Commit-Id: b9e4696533d4318ae7c8715b71ab963d8897c16c
Original-Change-Id: I6a7baf7859d5d50e299495d118e7890dcaa2c1b0
Original-Signed-off-by: Julius Werner <jwerner@chromium.org>
Original-Reviewed-on: https://chromium-review.googlesource.com/392206
Original-Tested-by: Shawn N <shawnn@chromium.org>
Original-Reviewed-by: Shawn N <shawnn@chromium.org>
Reviewed-on: https://review.coreboot.org/16885
Tested-by: build bot (Jenkins)
Reviewed-by: Martin Roth <martinroth@google.com>
This commit is contained in:
Julius Werner 2016-10-03 12:52:55 -07:00 committed by Patrick Georgi
parent e06a1b895c
commit 93b51e7ac9
1 changed files with 21 additions and 11 deletions
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32
src/ec/google/chromeec/ec_spi.c
View File

@ -20,6 +20,11 @@
#include <spi-generic.h>
#include <timer.h>
/* This is assuming that this driver is not used on x86. If that changes, this
might need to become a CAR_GLOBAL or maybe even more complicated. */
static struct stopwatch cs_cooldown_sw;
static const long cs_cooldown_us = 200;
static const uint8_t EcFramingByte = 0xec;
#define PROTO3_MAX_PACKET_SIZE 268
@ -44,7 +49,10 @@ void *crosec_get_buffer(size_t size, int req)
static int crosec_spi_io(size_t req_size, size_t resp_size, void *context)
{
struct spi_slave *slave = (struct spi_slave *)context;
int ret = 0;
while (!stopwatch_expired(&cs_cooldown_sw))
/* Wait minimum delay between CS assertions. */;
spi_claim_bus(slave);
/* Allow EC to ramp up clock after being awaken.
@ -53,8 +61,8 @@ static int crosec_spi_io(size_t req_size, size_t resp_size, void *context)
if (spi_xfer(slave, req_buf, req_size, NULL, 0)) {
printk(BIOS_ERR, "%s: Failed to send request.\n", __func__);
spi_release_bus(slave);
return -1;
ret = -1;
goto out;
}
uint8_t byte;
@ -65,8 +73,8 @@ static int crosec_spi_io(size_t req_size, size_t resp_size, void *context)
if (spi_xfer(slave, NULL, 0, &byte, sizeof(byte))) {
printk(BIOS_ERR, "%s: Failed to receive byte.\n",
__func__);
spi_release_bus(slave);
return -1;
ret = -1;
goto out;
}
if (byte == EcFramingByte)
break;
@ -75,28 +83,30 @@ static int crosec_spi_io(size_t req_size, size_t resp_size, void *context)
printk(BIOS_ERR,
"%s: Timeout waiting for framing byte.\n",
__func__);
spi_release_bus(slave);
return -1;
ret = -1;
goto out;
}
}
if (spi_xfer(slave, NULL, 0, resp_buf, resp_size)) {
printk(BIOS_ERR, "%s: Failed to receive response.\n", __func__);
spi_release_bus(slave);
return -1;
ret = -1;
}
out:
spi_release_bus(slave);
return 0;
stopwatch_init_usecs_expire(&cs_cooldown_sw, cs_cooldown_us);
return ret;
}
int google_chromeec_command(struct chromeec_command *cec_command)
{
static struct spi_slave *slave = NULL;
if (!slave)
if (!slave) {
slave = spi_setup_slave(CONFIG_EC_GOOGLE_CHROMEEC_SPI_BUS,
CONFIG_EC_GOOGLE_CHROMEEC_SPI_CHIP);
stopwatch_init(&cs_cooldown_sw);
}
return crosec_command_proto(cec_command, crosec_spi_io, slave);
}