From fe4d62708af53afd3e2df2074545f26f5e01c671 Mon Sep 17 00:00:00 2001 From: Aaron Durbin Date: Thu, 25 Feb 2016 17:17:35 -0600 Subject: soc/intel/skylake: add option to statically clock gate 8254 timer In order to save more power by shutting down clocks add the ability to optionally clock gate the 8254 programmable interrupt timer. When doing this the platforms lose their "PC"-ness which certain payloads and OSes rely on such as SeaBIOS. BUG=chrome-os-partner:50214 BRANCH=glados TEST=Enabled option on chell. Noted the bit is set upon booting. Change-Id: I01f9d177bbde417d1efec2e16656a07dcebccbde Signed-off-by: Patrick Georgi Original-Commit-Id: 662575aa6a63656dedfa0ce1f202f5fac0205477 Original-Change-Id: Ib4a613cf1c28fc96c36fa2987c4b58a05beab178 Original-Signed-off-by: Aaron Durbin Original-Reviewed-on: https://chromium-review.googlesource.com/329411 Original-Reviewed-by: Duncan Laurie Original-Reviewed-on: https://chromium-review.googlesource.com/331171 Original-Commit-Ready: Patrick Georgi Original-Tested-by: Patrick Georgi Reviewed-on: https://review.coreboot.org/13985 Tested-by: build bot (Jenkins) Reviewed-by: Martin Roth --- src/soc/intel/skylake/chip.h | 2 ++ src/soc/intel/skylake/include/soc/pcr.h | 3 +++ src/soc/intel/skylake/lpc.c | 13 +++++++++++++ 3 files changed, 18 insertions(+) (limited to 'src/soc') diff --git a/src/soc/intel/skylake/chip.h b/src/soc/intel/skylake/chip.h index e18b45a68a..ca902ae0ce 100644 --- a/src/soc/intel/skylake/chip.h +++ b/src/soc/intel/skylake/chip.h @@ -335,6 +335,8 @@ struct soc_intel_skylake_config { * 0 - Don't Send, 1 - Send */ u8 SendVrMbxCmd; + /* Statically clock gate 8254 PIT. */ + u8 clock_gate_8254; }; typedef struct soc_intel_skylake_config config_t; diff --git a/src/soc/intel/skylake/include/soc/pcr.h b/src/soc/intel/skylake/include/soc/pcr.h index 8a46cd1e5e..c3e8d83a90 100644 --- a/src/soc/intel/skylake/include/soc/pcr.h +++ b/src/soc/intel/skylake/include/soc/pcr.h @@ -60,6 +60,9 @@ #define R_PCH_PCR_ITSS_PIRQG_ROUT 0x3106 /* PIRQH Routing Control Register*/ #define R_PCH_PCR_ITSS_PIRQH_ROUT 0x3107 +/* ITSS Power reduction control */ +#define R_PCH_PCR_ITSS_ITSSPRC 0x3300 +# define CGE8254 (1 << 2) /* IO Trap PCRs */ /* Trap status Register */ diff --git a/src/soc/intel/skylake/lpc.c b/src/soc/intel/skylake/lpc.c index e47026c4f8..cebd836e9c 100644 --- a/src/soc/intel/skylake/lpc.c +++ b/src/soc/intel/skylake/lpc.c @@ -154,6 +154,18 @@ static const struct reg_script pch_misc_init_script[] = { REG_SCRIPT_END }; +static void clock_gate_8254(struct device *dev) +{ + config_t *config = dev->chip_info; + const uint32_t cge8254_mask = CGE8254; + + if (!config->clock_gate_8254) + return; + + pcr_andthenor32(PID_ITSS, R_PCH_PCR_ITSS_ITSSPRC, + ~cge8254_mask, cge8254_mask); +} + static void lpc_init(struct device *dev) { /* Legacy initialization */ @@ -165,6 +177,7 @@ static void lpc_init(struct device *dev) pch_pirq_init(dev); setup_i8259(); i8259_configure_irq_trigger(9, 1); + clock_gate_8254(dev); } static void pch_lpc_add_mmio_resources(device_t dev) -- cgit v1.2.3