The ACPI SPCR code has been used to enable console output for ARM64 and
X86. The same code can be reused for RISC-V.
Vendor will enable/disable the SPCR table in the firmware based on the
platform design. However, in cases where the SPCR table is not usable,
a kernel parameter could be used to specify the preferred console.
Signed-off-by: Sia Jee Heng <[email protected]>
---
arch/riscv/kernel/acpi.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
index e619edc8b0cc..5ec2fdf9e09f 100644
--- a/arch/riscv/kernel/acpi.c
+++ b/arch/riscv/kernel/acpi.c
@@ -18,6 +18,7 @@
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/pci.h>
+#include <linux/serial_core.h>
int acpi_noirq = 1; /* skip ACPI IRQ initialization */
int acpi_disabled = 1;
@@ -151,6 +152,9 @@ void __init acpi_boot_table_init(void)
if (!param_acpi_force)
disable_acpi();
}
+
+ if (!acpi_disabled)
+ acpi_parse_spcr(earlycon_acpi_spcr_enable, true);
}
static int acpi_parse_madt_rintc(union acpi_subtable_headers *header, const unsigned long end)
--
2.34.1
On Fri, Dec 29, 2023 at 02:54:05PM +0800, Sia Jee Heng wrote:
> The ACPI SPCR code has been used to enable console output for ARM64 and
> X86. The same code can be reused for RISC-V.
>
> Vendor will enable/disable the SPCR table in the firmware based on the
> platform design. However, in cases where the SPCR table is not usable,
> a kernel parameter could be used to specify the preferred console.
>
> Signed-off-by: Sia Jee Heng <[email protected]>
> ---
> arch/riscv/kernel/acpi.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
> index e619edc8b0cc..5ec2fdf9e09f 100644
> --- a/arch/riscv/kernel/acpi.c
> +++ b/arch/riscv/kernel/acpi.c
> @@ -18,6 +18,7 @@
> #include <linux/io.h>
> #include <linux/memblock.h>
> #include <linux/pci.h>
> +#include <linux/serial_core.h>
>
> int acpi_noirq = 1; /* skip ACPI IRQ initialization */
> int acpi_disabled = 1;
> @@ -151,6 +152,9 @@ void __init acpi_boot_table_init(void)
> if (!param_acpi_force)
> disable_acpi();
> }
> +
> + if (!acpi_disabled)
> + acpi_parse_spcr(earlycon_acpi_spcr_enable, true);
Both arm64 and loongarch call early_init_dt_scan_chosen_stdout() when
acpi_disabled and earlycon_acpi_spcr_enable are both true. Is that
not necessary for RISC-V?
Thanks,
drew
> }
>
> static int acpi_parse_madt_rintc(union acpi_subtable_headers *header, const unsigned long end)
> --
> 2.34.1
>
> -----Original Message-----
> From: Andrew Jones <[email protected]>
> Sent: Tuesday, January 2, 2024 11:39 PM
> To: JeeHeng Sia <[email protected]>
> Cc: [email protected]; [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected]; [email protected]
> Subject: Re: [RFC v1 1/1] RISC-V: ACPI: Enable SPCR table for console output on RISC-V
>
> On Fri, Dec 29, 2023 at 02:54:05PM +0800, Sia Jee Heng wrote:
> > The ACPI SPCR code has been used to enable console output for ARM64 and
> > X86. The same code can be reused for RISC-V.
> >
> > Vendor will enable/disable the SPCR table in the firmware based on the
> > platform design. However, in cases where the SPCR table is not usable,
> > a kernel parameter could be used to specify the preferred console.
> >
> > Signed-off-by: Sia Jee Heng <[email protected]>
> > ---
> > arch/riscv/kernel/acpi.c | 4 ++++
> > 1 file changed, 4 insertions(+)
> >
> > diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
> > index e619edc8b0cc..5ec2fdf9e09f 100644
> > --- a/arch/riscv/kernel/acpi.c
> > +++ b/arch/riscv/kernel/acpi.c
> > @@ -18,6 +18,7 @@
> > #include <linux/io.h>
> > #include <linux/memblock.h>
> > #include <linux/pci.h>
> > +#include <linux/serial_core.h>
> >
> > int acpi_noirq = 1; /* skip ACPI IRQ initialization */
> > int acpi_disabled = 1;
> > @@ -151,6 +152,9 @@ void __init acpi_boot_table_init(void)
> > if (!param_acpi_force)
> > disable_acpi();
> > }
> > +
> > + if (!acpi_disabled)
> > + acpi_parse_spcr(earlycon_acpi_spcr_enable, true);
>
> Both arm64 and loongarch call early_init_dt_scan_chosen_stdout() when
> acpi_disabled and earlycon_acpi_spcr_enable are both true. Is that
> not necessary for RISC-V?
It is needed for device tree support. However, since this patch targets
ACPI, that's why I didn't include a DT solution in this patch. I can
submit a separate patch targeting DT-based earlycon if needed. Please let
me know if you think otherwise.
>
> Thanks,
> drew
>
> > }
> >
> > static int acpi_parse_madt_rintc(union acpi_subtable_headers *header, const unsigned long end)
> > --
> > 2.34.1
> >