Received-SPF: pass (google.com: domain of linux-kernel+bounces-12961-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3;
From: Sia Jee Heng <jeeheng.sia@starfivetech.com>
To: <linux-kernel@vger.kernel.org>, <linux-riscv@lists.infradead.org>
CC: <rafael.j.wysocki@intel.com>, <ajones@ventanamicro.com>,
	<conor.dooley@microchip.com>, <sunilvl@ventanamicro.com>,
	<jeeheng.sia@starfivetech.com>, <aou@eecs.berkeley.edu>,
	<palmer@dabbelt.com>, <paul.walmsley@sifive.com>
Subject: [RFC v1 1/1] RISC-V: ACPI: Enable SPCR table for console output on RISC-V
Date: Fri, 29 Dec 2023 14:54:05 +0800
Message-ID: <20231229065405.235625-2-jeeheng.sia@starfivetech.com>
In-Reply-To: <20231229065405.235625-1-jeeheng.sia@starfivetech.com>
References: <20231229065405.235625-1-jeeheng.sia@starfivetech.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain
Content-Transfer-Encoding: quoted-printable

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 <jeeheng.sia@starfivetech.com>
---
 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>
=20
 int acpi_noirq =3D 1;		/* skip ACPI IRQ initialization */
 int acpi_disabled =3D 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);
 }
=20
 static int acpi_parse_madt_rintc(union acpi_subtable_headers *header, co=
nst unsigned long end)
--=20
2.34.1