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/Kconfig | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'src/ec/google/chromeec/Kconfig') diff --git a/src/ec/google/chromeec/Kconfig b/src/ec/google/chromeec/Kconfig index bec12fb10a..32a42133f2 100644 --- a/src/ec/google/chromeec/Kconfig +++ b/src/ec/google/chromeec/Kconfig @@ -43,6 +43,13 @@ config EC_GOOGLE_CHROMEEC_SPI_BUS depends on EC_GOOGLE_CHROMEEC_SPI hex "SPI bus for Google's Chrome EC" +config EC_GOOGLE_CHROMEEC_SPI_WAKEUP_DELAY_US + depends on EC_GOOGLE_CHROMEEC_SPI + int + default 0 + help + Force delay after asserting /CS to allow EC to wakeup. + config EC_GOOGLE_CHROMEEC_SPI_CHIP depends on EC_GOOGLE_CHROMEEC_SPI hex -- cgit v1.2.3