Hi BIn, On Sun, 1 Dec 2019 at 23:31, Bin Meng <bmeng...@gmail.com> wrote: > > Hi Simon, > > On Mon, Nov 25, 2019 at 12:12 PM Simon Glass <s...@chromium.org> wrote: > > > > This driver handles communication with the systemagent which needs to be > > told when U-Boot has completed its init. > > > > Signed-off-by: Simon Glass <s...@chromium.org> > > > > --- > > > > Changes in v5: None > > Changes in v4: > > - Add a comment for enable_bios_reset_cpl() > > - Tidy up header guards > > - use GENMASK() for VTBAR_MASK > > > > Changes in v3: None > > Changes in v2: None > > > > arch/x86/cpu/apollolake/Makefile | 2 + > > arch/x86/cpu/apollolake/systemagent.c | 19 ++++++++++ > > .../include/asm/arch-apollolake/systemagent.h | 37 +++++++++++++++++++ > > 3 files changed, 58 insertions(+) > > create mode 100644 arch/x86/cpu/apollolake/systemagent.c > > create mode 100644 arch/x86/include/asm/arch-apollolake/systemagent.h > > > > diff --git a/arch/x86/cpu/apollolake/Makefile > > b/arch/x86/cpu/apollolake/Makefile > > index fdda748ea3..3a8c2f66a3 100644 > > --- a/arch/x86/cpu/apollolake/Makefile > > +++ b/arch/x86/cpu/apollolake/Makefile > > @@ -2,5 +2,7 @@ > > # > > # Copyright 2019 Google LLC > > > > +obj-$(CONFIG_SPL_BUILD) += systemagent.o > > + > > obj-y += pmc.o > > obj-y += uart.o > > diff --git a/arch/x86/cpu/apollolake/systemagent.c > > b/arch/x86/cpu/apollolake/systemagent.c > > new file mode 100644 > > index 0000000000..3a41b329c3 > > --- /dev/null > > +++ b/arch/x86/cpu/apollolake/systemagent.c > > @@ -0,0 +1,19 @@ > > +// SPDX-License-Identifier: GPL-2.0 > > +/* > > + * Copyright (C) 2017 Intel Corporation. > > + * Take from coreboot project file of the same name > > + */ > > + > > +#include <common.h> > > +#include <asm/intel_regs.h> > > +#include <asm/io.h> > > +#include <asm/arch/systemagent.h> > > + > > +void enable_bios_reset_cpl(void) > > +{ > > + /* > > + * Set bits 0+1 of BIOS_RESET_CPL to indicate to the CPU > > + * that BIOS has initialised memory and power management > > + */ > > Is this absolutely necessary? What happens if we don't do this? Or > does FSP-S do such for us?
The FSP-S does not do it. If we leave this as zero then I believe the power-aware interrupts don't work in Linux, and cpu 0 always gets the interrupt. Regards, Simon