[kvm-unit-tests PATCH v3 08/27] arm/arm64: Add support for discovering the UART through ACPI

Nikos Nikoleris
2022-06-30T10:04:05Z

In systems with ACPI support and when a DT is not provided, we can use
the SPCR to discover the serial port address range. This change
implements this but retains the default behavior; we check if a valid
DT is provided, if not, we try to discover the UART using ACPI.

Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Ricardo Koller <ricarkol@google.com>
---
lib/acpi.h | 25 +++++++++++++++++++++++++
lib/arm/io.c | 23 ++++++++++++++++++-----
2 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/lib/acpi.h b/lib/acpi.h
index 6c18f73..1cd99c5 100644
--- a/lib/acpi.h
+++ b/lib/acpi.h
@@ -17,6 +17,7 @@
#define XSDT_SIGNATURE ACPI_SIGNATURE('X','S','D','T')
#define FACP_SIGNATURE ACPI_SIGNATURE('F','A','C','P')
#define FACS_SIGNATURE ACPI_SIGNATURE('F','A','C','S')
+#define SPCR_SIGNATURE ACPI_SIGNATURE('S','P','C','R')

#define ACPI_SIGNATURE_8BYTE(c1, c2, c3, c4, c5, c6, c7, c8) \
@@ -148,6 +149,30 @@ struct facs_descriptor_rev1
u8 reserved3 [40]; /* Reserved - must be zero */
};

+struct spcr_descriptor {
+ ACPI_TABLE_HEADER_DEF /* ACPI common table header */
+ u8 interface_type; /* 0=full 16550, 1=subset of 16550 */
+ u8 reserved[3];
+ struct acpi_generic_address serial_port;
+ u8 interrupt_type;
+ u8 pc_interrupt;
+ u32 interrupt;
+ u8 baud_rate;
+ u8 parity;
+ u8 stop_bits;
+ u8 flow_control;
+ u8 terminal_type;
+ u8 reserved1;
+ u16 pci_device_id;
+ u16 pci_vendor_id;
+ u8 pci_bus;
+ u8 pci_device;
+ u8 pci_function;
+ u32 pci_flags;
+ u8 pci_segment;
+ u32 reserved2;
+};
+
#pragma pack(0)

void set_efi_rsdp(struct rsdp_descriptor *rsdp);
diff --git a/lib/arm/io.c b/lib/arm/io.c
index 343e108..a91f116 100644
--- a/lib/arm/io.c
+++ b/lib/arm/io.c
@@ -9,6 +9,7 @@
* This work is licensed under the terms of the GNU LGPL, version 2.
*/
#include <libcflat.h>
+#include <acpi.h>
#include <devicetree.h>
#include <chr-testdev.h>
#include <config.h>
@@ -29,7 +30,7 @@ static struct spinlock uart_lock;
#define UART_EARLY_BASE (u8 *)(unsigned long)CONFIG_UART_EARLY_BASE
static volatile u8 *uart0_base = UART_EARLY_BASE;

-static void uart0_init(void)
+static void uart0_init_fdt(void)
{
/*
* kvm-unit-tests uses the uart only for output. Both uart models have
@@ -65,17 +66,29 @@ static void uart0_init(void)
}

uart0_base = ioremap(base.addr, base.size);
+}
+
+static void uart0_init_acpi(void)
+{
+ struct spcr_descriptor *spcr = find_acpi_table_addr(SPCR_SIGNATURE);
+
+ assert_msg(spcr, "Unable to find ACPI SPCR");
+ uart0_base = ioremap(spcr->serial_port.address, spcr->serial_port.bit_width);
+}
+
+void io_init(void)
+{
+ if (dt_available())
+ uart0_init_fdt();
+ else
+ uart0_init_acpi();

if (uart0_base != UART_EARLY_BASE) {
printf("WARNING: early print support may not work. "
"Found uart at %p, but early base is %p.\n",
uart0_base, UART_EARLY_BASE);
}
-}

-void io_init(void)
-{
- uart0_init();
chr_testdev_init();
}

--
2.25.1