From 22c040fa21b604b9b3d88645e108fb2f0a74474b Mon Sep 17 00:00:00 2001 From: Enric Balletbo i Serra Date: Fri, 14 Jun 2019 23:43:01 +0200 Subject: platform/chrome: cros_ec_lpc: Choose Microchip EC at runtime On many boards, communication between the kernel and the Embedded Controller happens over an LPC bus. In these cases, the kernel config CONFIG_CROS_EC_LPC is enabled. Some of these LPC boards contain a Microchip Embedded Controller (MEC) that is different from the regular EC. On these devices, the same LPC bus is used, but the protocol is a little different. In these cases, the CONFIG_CROS_EC_LPC_MEC kernel config is enabled. Currently, the kernel decides at compile-time whether or not to use the MEC variant, and, when that kernel option is selected it breaks the other boards. We would like a kind of runtime detection to avoid this. This patch adds that detection mechanism by probing the protocol at runtime, first we assume that a MEC variant is connected, and if the protocol fails it fallbacks to the regular EC. This adds a bit of overload because we try to read twice on those LPC boards that doesn't contain a MEC variant, but is a better solution than having to select the EC variant at compile-time. While here also fix the alignment in Kconfig file for this config option replacing the spaces by tabs. Signed-off-by: Enric Balletbo i Serra Reviewed-by: Ezequiel Garcia Tested-by: Nick Crews Reviewed-by: Nick Crews --- drivers/platform/chrome/Kconfig | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-) (limited to 'drivers/platform/chrome/Kconfig') diff --git a/drivers/platform/chrome/Kconfig b/drivers/platform/chrome/Kconfig index 0b3c2b9ffd2f..8010e7e395ce 100644 --- a/drivers/platform/chrome/Kconfig +++ b/drivers/platform/chrome/Kconfig @@ -95,28 +95,17 @@ config CROS_EC_SPI 'pre-amble' bytes before the response actually starts. config CROS_EC_LPC - tristate "ChromeOS Embedded Controller (LPC)" - depends on MFD_CROS_EC && ACPI && (X86 || COMPILE_TEST) - help - If you say Y here, you get support for talking to the ChromeOS EC - over an LPC bus. This uses a simple byte-level protocol with a - checksum. This is used for userspace access only. The kernel - typically has its own communication methods. - - To compile this driver as a module, choose M here: the - module will be called cros_ec_lpc. - -config CROS_EC_LPC_MEC - bool "ChromeOS Embedded Controller LPC Microchip EC (MEC) variant" - depends on CROS_EC_LPC - default n + tristate "ChromeOS Embedded Controller (LPC)" + depends on MFD_CROS_EC && ACPI && (X86 || COMPILE_TEST) help - If you say Y here, a variant LPC protocol for the Microchip EC - will be used. Note that this variant is not backward compatible - with non-Microchip ECs. + If you say Y here, you get support for talking to the ChromeOS EC + over an LPC bus, including the LPC Microchip EC (MEC) variant. + This uses a simple byte-level protocol with a checksum. This is + used for userspace access only. The kernel typically has its own + communication methods. - If you have a ChromeOS Embedded Controller Microchip EC variant - choose Y here. + To compile this driver as a module, choose M here: the + module will be called cros_ec_lpcs. config CROS_EC_PROTO bool -- cgit v1.2.3-59-g8ed1b