[PATCH v7 18/37] drivers/cpu: Add generic armv8 cpu driver

Patrick Rudolph
2024-10-11T10:37:17Z

Add a generic driver that binds to armv8 CPU nodes. The generic driver allows
- to enumerate CPUs present in a system, even when no other driver binds it
- generates ACPI SSDT code for each CPU
- Fill the ACPI MADT table (implemented in a follow up patch)

The newly introduced code could also be reused on other CPU drivers that are
compatible with armv8.

TEST: Booted on QEMU sbsa and verify the driver binds to CPU nodes.
Confirmed with FWTS that all ACPI processor devices are present.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>
Cc: Simon Glass <sjg@chromium.org>
---
Changelog v4:
- Export armv8_cpu_fill_ssdt to use it in other CPU drivers
Changelog v6:
- Update header order

---
drivers/cpu/Kconfig | 6 ++++
drivers/cpu/Makefile | 2 ++
drivers/cpu/armv8_cpu.c | 73 +++++++++++++++++++++++++++++++++++++++++
drivers/cpu/armv8_cpu.h | 21 ++++++++++++
4 files changed, 102 insertions(+)
create mode 100644 drivers/cpu/armv8_cpu.c
create mode 100644 drivers/cpu/armv8_cpu.h

diff --git a/drivers/cpu/Kconfig b/drivers/cpu/Kconfig
index 5c06cd9f60..9c0df331d7 100644
--- a/drivers/cpu/Kconfig
+++ b/drivers/cpu/Kconfig
@@ -26,6 +26,12 @@ config CPU_RISCV
help
Support CPU cores for RISC-V architecture.

+config CPU_ARMV8
+ bool "Enable generic ARMv8 CPU driver"
+ depends on CPU && ARM64
+ help
+ Support CPU cores for armv8 architecture.
+
config CPU_MICROBLAZE
bool "Enable Microblaze CPU driver"
depends on CPU && MICROBLAZE
diff --git a/drivers/cpu/Makefile b/drivers/cpu/Makefile
index bc75d9b974..773395693a 100644
--- a/drivers/cpu/Makefile
+++ b/drivers/cpu/Makefile
@@ -6,10 +6,12 @@

obj-$(CONFIG_CPU) += cpu-uclass.o

+
obj-$(CONFIG_ARCH_BMIPS) += bmips_cpu.o
obj-$(CONFIG_ARCH_IMX8) += imx8_cpu.o
obj-$(CONFIG_ARCH_AT91) += at91_cpu.o
obj-$(CONFIG_ARCH_MEDIATEK) += mtk_cpu.o
+obj-$(CONFIG_CPU_ARMV8) += armv8_cpu.o
obj-$(CONFIG_CPU_IMX) += imx8_cpu.o
obj-$(CONFIG_CPU_MPC83XX) += mpc83xx_cpu.o
obj-$(CONFIG_CPU_RISCV) += riscv_cpu.o
diff --git a/drivers/cpu/armv8_cpu.c b/drivers/cpu/armv8_cpu.c
new file mode 100644
index 0000000000..19f072be43
--- /dev/null
+++ b/drivers/cpu/armv8_cpu.c
@@ -0,0 +1,73 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2024 9elements GmbH
+ */
+#include <cpu.h>
+#include <dm.h>
+#include <acpi/acpigen.h>
+#include <asm/armv8/cpu.h>
+#include <dm/acpi.h>
+#include <asm/io.h>
+#include <linux/bitops.h>
+#include <linux/printk.h>
+#include <linux/sizes.h>
+
+static int armv8_cpu_get_desc(const struct udevice *dev, char *buf, int size)
+{
+ int cpuid;
+
+ cpuid = (read_midr() & MIDR_PARTNUM_MASK) >> MIDR_PARTNUM_SHIFT;
+
+ snprintf(buf, size, "CPU MIDR %04x", cpuid);
+
+ return 0;
+}
+
+static int armv8_cpu_get_info(const struct udevice *dev,
+ struct cpu_info *info)
+{
+ info->cpu_freq = 0;
+ info->features = BIT(CPU_FEAT_L1_CACHE) | BIT(CPU_FEAT_MMU);
+
+ return 0;
+}
+
+static int armv8_cpu_get_count(const struct udevice *dev)
+{
+ return uclass_id_count(UCLASS_CPU);
+}
+
+#ifdef CONFIG_ACPIGEN
+int armv8_cpu_fill_ssdt(const struct udevice *dev, struct acpi_ctx *ctx)
+{
+ uint core_id = dev_seq(dev);
+
+ acpigen_write_processor_device(ctx, core_id);
+
+ return 0;
+}
+
+struct acpi_ops armv8_cpu_acpi_ops = {
+ .fill_ssdt = armv8_cpu_fill_ssdt,
+};
+#endif
+
+static const struct cpu_ops cpu_ops = {
+ .get_count = armv8_cpu_get_count,
+ .get_desc = armv8_cpu_get_desc,
+ .get_info = armv8_cpu_get_info,
+};
+
+static const struct udevice_id cpu_ids[] = {
+ { .compatible = "arm,armv8" },
+ {}
+};
+
+U_BOOT_DRIVER(arm_cpu) = {
+ .name = "arm-cpu",
+ .id = UCLASS_CPU,
+ .of_match = cpu_ids,
+ .ops = &cpu_ops,
+ .flags = DM_FLAG_PRE_RELOC,
+ ACPI_OPS_PTR(&armv8_cpu_acpi_ops)
+};
diff --git a/drivers/cpu/armv8_cpu.h b/drivers/cpu/armv8_cpu.h
new file mode 100644
index 0000000000..2c4b0252cf
--- /dev/null
+++ b/drivers/cpu/armv8_cpu.h
@@ -0,0 +1,21 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2024 9elements GmbH
+ */
+#include <dm/acpi.h>
+#include <dm/device.h>
+
+#ifndef _ARMV8_CPU_H_
+#define _ARMV8_CPU_H_
+
+/**
+ * armv8_cpu_fill_ssdt() - Fill the SSDT
+ * Parses the FDT and writes the SSDT nodes.
+ *
+ * @dev: cpu device to generate ACPI tables for
+ * @ctx: ACPI context pointer
+ * @return: 0 if OK, or a negative error code.
+ */
+int armv8_cpu_fill_ssdt(const struct udevice *dev, struct acpi_ctx *ctx);
+
+#endif
\ No newline at end of file
--
2.46.2