[PATCH v6 33/37] arm: mach-bcm283x: Add ARMV8_MULTIENTRY support

Patrick Rudolph
2024-10-02T09:57:57Z

When ACPI is enabled over FDT the APs cannot be brought out of reset
by the OS using the "FDT spin-table" mechanism, as no FDT is provided
to the OS. The APs must be released out of reset in u-boot and then
brought up in an ACPI compliant fashion.

When ARMV8_MULTIENTRY is specified, the APs are released from reset
and will enter U-Boot after it has been relocated as well.

By default ARMV8_MULTIENTRY is not selected, keeping existing behaviour.

TEST: All APs enter U-Boot when run on qemu-system-aarch64 and on
real hardware.

Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Cc: Matthias Brugger <mbrugger@suse.com>
Cc: Peter Robinson <pbrobinson@gmail.com>
Cc: Tom Rini <trini@konsulko.com>
---
Changelog v2:
- Drop CPU code from board
- Add CPU driver to release APs from reset
Changelog v4:
- Use the generic armv8 CPU driver
- Probe all CPUs
- Release secondary CPUs in the probe function
- Use of_to_plat() to parse DT
- Drop udelay()
- Select the GICv2 driver
Changelog v5:
- Cosmetic fixes
- Drop arch_early_init_r()
Changelog v6:
- Update header order
- Drop ifdef
---
arch/arm/Kconfig | 1 +
arch/arm/mach-bcm283x/Kconfig | 5 +-
drivers/cpu/Makefile | 2 +-
drivers/cpu/bcm283x_cpu.c | 214 ++++++++++++++++++++++++++++++++++
4 files changed, 220 insertions(+), 2 deletions(-)
create mode 100644 drivers/cpu/bcm283x_cpu.c

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 985dd8f3da..94ab271370 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -651,6 +651,7 @@ config ARCH_ORION5X

config ARCH_BCM283X
bool "Broadcom BCM283X family"
+ select CPU
select DM
select DM_GPIO
select DM_SERIAL
diff --git a/arch/arm/mach-bcm283x/Kconfig b/arch/arm/mach-bcm283x/Kconfig
index b3287ce8bc..0ef8156c64 100644
--- a/arch/arm/mach-bcm283x/Kconfig
+++ b/arch/arm/mach-bcm283x/Kconfig
@@ -24,7 +24,9 @@ config BCM2837_64B
bool "Broadcom BCM2837 SoC 64-bit support"
depends on ARCH_BCM283X
select BCM2837
+ select DRIVER_GICV2
select ARM64
+ select CPU_ARMV8

config BCM2711
bool "Broadcom BCM2711 SoC support"
@@ -42,11 +44,12 @@ config BCM2711_64B
bool "Broadcom BCM2711 SoC 64-bit support"
depends on ARCH_BCM283X
select BCM2711
+ select DRIVER_GICV2
select ARM64
+ select CPU_ARMV8

menu "Broadcom BCM283X family"
depends on ARCH_BCM283X
-
choice
prompt "Broadcom BCM283X board select"
optional
diff --git a/drivers/cpu/Makefile b/drivers/cpu/Makefile
index 773395693a..eaf494706e 100644
--- a/drivers/cpu/Makefile
+++ b/drivers/cpu/Makefile
@@ -6,7 +6,7 @@

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

-
+obj-$(CONFIG_ARCH_BCM283X) += bcm283x_cpu.o
obj-$(CONFIG_ARCH_BMIPS) += bmips_cpu.o
obj-$(CONFIG_ARCH_IMX8) += imx8_cpu.o
obj-$(CONFIG_ARCH_AT91) += at91_cpu.o
diff --git a/drivers/cpu/bcm283x_cpu.c b/drivers/cpu/bcm283x_cpu.c
new file mode 100644
index 0000000000..59a7b142c9
--- /dev/null
+++ b/drivers/cpu/bcm283x_cpu.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2024 9elements GmbH
+ */
+
+#include <cpu.h>
+#include <cpu_func.h>
+#include <dm.h>
+#include <fdt_support.h>
+#include <acpi/acpigen.h>
+#include <asm/armv8/cpu.h>
+#include <asm/cache.h>
+#include <asm/io.h>
+#include <asm/global_data.h>
+#include <asm/system.h>
+#include <asm-generic/sections.h>
+#include <linux/bitops.h>
+#include <linux/clk-provider.h>
+#include <linux/delay.h>
+#include "armv8_cpu.h"
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct bcm_plat {
+ u64 release_addr;
+};
+
+static int cpu_bcm_get_desc(const struct udevice *dev, char *buf, int size)
+{
+ struct cpu_plat *plat = dev_get_parent_plat(dev);
+ const char *name;
+
+ if (size < 32)
+ return -ENOSPC;
+
+ if (device_is_compatible(dev, "arm,cortex-a53"))
+ name = "A53";
+ else if (device_is_compatible(dev, "arm,cortex-a72"))
+ name = "A72";
+ else
+ name = "?";
+
+ snprintf(buf, size, "Broadcom Cortex-%s at %u MHz\n",
+ name, plat->timebase_freq);
+
+ return 0;
+}
+
+static int cpu_bcm_get_info(const struct udevice *dev, struct cpu_info *info)
+{
+ struct cpu_plat *plat = dev_get_parent_plat(dev);
+
+ info->cpu_freq = plat->timebase_freq * 1000;
+ info->features = BIT(CPU_FEAT_L1_CACHE) | BIT(CPU_FEAT_MMU);
+
+ return 0;
+}
+
+static int cpu_bcm_get_count(const struct udevice *dev)
+{
+ return uclass_id_count(UCLASS_CPU);
+}
+
+static int cpu_bcm_get_vendor(const struct udevice *dev, char *buf, int size)
+{
+ snprintf(buf, size, "Broadcom");
+
+ return 0;
+}
+
+static int cpu_bcm_is_current(struct udevice *dev)
+{
+ struct cpu_plat *plat = dev_get_parent_plat(dev);
+
+ if (plat->cpu_id == (read_mpidr() & 0xffff))
+ return 1;
+
+ return 0;
+}
+
+/**
+ * bcm_cpu_on - Releases the secondary CPU from it's spintable
+ *
+ * Write the CPU's spintable mailbox and let the CPU enter U-Boot.
+ *
+ * @dev: Device to start
+ * @return: zero on success or error code on failure.
+ */
+static int bcm_cpu_on(struct udevice *dev)
+{
+ struct bcm_plat *plat = dev_get_plat(dev);
+ ulong *start_address;
+
+ if (plat->release_addr == ~0ULL)
+ return -ENODATA;
+
+ start_address = map_physmem(plat->release_addr, sizeof(uintptr_t), MAP_NOCACHE);
+
+ /* Point secondary CPU to U-Boot entry */
+ *start_address = (uintptr_t)_start;
+
+ /* Make sure the other CPUs see the written start address */
+ if (!CONFIG_IS_ENABLED(SYS_DCACHE_OFF))
+ flush_dcache_all();
+
+ /* Send an event to wake up the secondary CPU. */
+ asm("dsb ishst\n"
+ "sev");
+
+ unmap_physmem(start_address, MAP_NOCACHE);
+
+ return 0;
+}
+
+static const struct cpu_ops cpu_bcm_ops = {
+ .get_desc = cpu_bcm_get_desc,
+ .get_info = cpu_bcm_get_info,
+ .get_count = cpu_bcm_get_count,
+ .get_vendor = cpu_bcm_get_vendor,
+ .is_current = cpu_bcm_is_current,
+};
+
+static const struct udevice_id cpu_bcm_ids[] = {
+ { .compatible = "arm,cortex-a53" }, /* RPi 3 */
+ { .compatible = "arm,cortex-a72" }, /* RPi 4 */
+ { }
+};
+
+static int bcm_cpu_bind(struct udevice *dev)
+{
+ struct cpu_plat *plat = dev_get_parent_plat(dev);
+
+ plat->cpu_id = dev_read_addr(dev);
+
+ return 0;
+}
+
+/**
+ * bcm_cpu_of_to_plat - Gather spin-table release address
+ *
+ * Read the spin-table release address to allow all seconary CPUs to enter
+ * U-Boot when necessary.
+ *
+ * @dev: Device to start
+ */
+static int bcm_cpu_of_to_plat(struct udevice *dev)
+{
+ struct bcm_plat *plat = dev_get_plat(dev);
+ const char *prop;
+
+ if (CONFIG_IS_ENABLED(ARMV8_MULTIENTRY)) {
+ plat->release_addr = ~0ULL;
+
+ prop = dev_read_string(dev, "enable-method");
+ if (!prop || strcmp(prop, "spin-table"))
+ return -ENODEV;
+
+ plat->release_addr = dev_read_u64_default(dev, "cpu-release-addr", ~0ULL);
+
+ if (plat->release_addr == ~0ULL)
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
+static int bcm_cpu_probe(struct udevice *dev)
+{
+ struct cpu_plat *plat = dev_get_parent_plat(dev);
+ struct clk clk;
+ int ret;
+
+ /* Get a clock if it exists */
+ ret = clk_get_by_index(dev, 0, &clk);
+ if (!ret) {
+ ret = clk_enable(&clk);
+ if (ret && (ret != -ENOSYS || ret != -EOPNOTSUPP))
+ return ret;
+ ret = clk_get_rate(&clk);
+ if (IS_ERR_VALUE(ret))
+ return ret;
+ plat->timebase_freq = ret;
+ }
+
+ /*
+ * The armstub holds the secondary CPUs in a spinloop. When
+ * ARMV8_MULTIENTRY is enabled release the secondary CPUs and
+ * let them enter U-Boot as well.
+ */
+ if (CONFIG_IS_ENABLED(ARMV8_MULTIENTRY)) {
+ ret = bcm_cpu_on(dev);
+ if (ret)
+ return ret;
+ }
+
+ return ret;
+}
+
+struct acpi_ops bcm283x_cpu_acpi_ops = {
+ .fill_ssdt = armv8_cpu_fill_ssdt,
+ .fill_madt = armv8_cpu_fill_madt,
+};
+
+U_BOOT_DRIVER(cpu_bcm_drv) = {
+ .name = "bcm283x_cpu",
+ .id = UCLASS_CPU,
+ .of_match = cpu_bcm_ids,
+ .ops = &cpu_bcm_ops,
+ .probe = bcm_cpu_probe,
+ .bind = bcm_cpu_bind,
+ .of_to_plat = bcm_cpu_of_to_plat,
+ .plat_auto = sizeof(struct bcm_plat),
+ ACPI_OPS_PTR(&bcm283x_cpu_acpi_ops)
+};
--
2.46.2