From 767d245ebf2d6d797bf759d23778553ed6f2a0b2 Mon Sep 17 00:00:00 2001 From: David Hendricks Date: Sat, 27 Sep 2014 20:04:49 -0700 Subject: chromeec: Add wakeup delay after SPI /CS assertion Some ECs may require a few microseconds to ramp up their clock after being awaken by /CS assertion. This adds a Kconfig variable that can be overridden at the mainboard-level which will force a delay between asserting /CS and beginning a transfer. BUG=chrome-os-partner:32223 BRANCH=none TEST=verified ~100us delay using logic analyzer Change-Id: I6d9b8beaa808252f008efb10e7448afdf96d2004 Signed-off-by: Stefan Reinauer Original-Commit-Id: ec6b10e4e3f0362dea0dc8046cfd4e4615a42585 Original-Change-Id: Ibba356e4af18f80a7da73c96dadfda0f25251381 Original-Signed-off-by: David Hendricks Original-Reviewed-on: https://chromium-review.googlesource.com/220242 Original-Reviewed-by: Julius Werner Original-Reviewed-by: Alexandru Stan Reviewed-on: http://review.coreboot.org/9217 Reviewed-by: David Hendricks Tested-by: build bot (Jenkins) --- src/ec/google/chromeec/ec_spi.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'src/ec/google/chromeec/ec_spi.c') diff --git a/src/ec/google/chromeec/ec_spi.c b/src/ec/google/chromeec/ec_spi.c index 4b3e587266..d11348cff7 100644 --- a/src/ec/google/chromeec/ec_spi.c +++ b/src/ec/google/chromeec/ec_spi.c @@ -18,6 +18,7 @@ */ #include +#include #include "ec.h" #include "ec_commands.h" #include @@ -50,6 +51,10 @@ static int crosec_spi_io(size_t req_size, size_t resp_size, void *context) spi_claim_bus(slave); + /* Allow EC to ramp up clock after being awaken. + * See chrome-os-partner:32223 for more details. */ + udelay(CONFIG_EC_GOOGLE_CHROMEEC_SPI_WAKEUP_DELAY_US); + if (spi_xfer(slave, req_buf, req_size, NULL, 0)) { printk(BIOS_ERR, "%s: Failed to send request.\n", __func__); spi_release_bus(slave); -- cgit v1.2.3