From 0eefa005030a70f5c691155b931bb778ad1fb2ae Mon Sep 17 00:00:00 2001 From: Duncan Laurie Date: Mon, 16 Jul 2012 12:11:53 -0700 Subject: ACPI: Add function to write _PPC using NVS The existing NVS variable for PPCM will be used to select a dynamic max P-state. By itself this does not change existing behavior because the NVS PPCM variable is initialized to zero. PPCM can be tested by building and booting a modified BIOS that sets gnvs->ppcm to a value greater than 1 and checking from the OS that the P-state is limited to that value. Change-Id: Ia7b3bbc6b84c1aa42349bb236abee5cc92486561 Signed-off-by: Duncan Laurie Reviewed-on: http://review.coreboot.org/1341 Tested-by: build bot (Jenkins) Reviewed-by: Ronald G. Minnich --- src/arch/x86/boot/acpigen.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) (limited to 'src/arch/x86/boot/acpigen.c') diff --git a/src/arch/x86/boot/acpigen.c b/src/arch/x86/boot/acpigen.c index 71aa10cd17..47845a01a6 100644 --- a/src/arch/x86/boot/acpigen.c +++ b/src/arch/x86/boot/acpigen.c @@ -396,6 +396,32 @@ int acpigen_write_PPC(u8 nr) return len; } +/* generates a func with max supported P states */ +int acpigen_write_PPC_NVS(void) +{ +/* + Method (_PPC, 0, NotSerialized) + { + Return (PPCM) + } +*/ + int len; + /* method op */ + acpigen_emit_byte(0x14); + len = acpigen_write_len_f(); + len += acpigen_emit_namestring("_PPC"); + /* no fnarg */ + acpigen_emit_byte(0x00); + /* return */ + acpigen_emit_byte(0xa4); + /* arg */ + len += acpigen_emit_namestring("PPCM"); + /* add all single bytes */ + len += 3; + acpigen_patch_len(len - 1); + return len; +} + int acpigen_write_TPC(const char *gnvs_tpc_limit) { /* -- cgit v1.2.3