[U-Boot] [PATCH 1/7] riscv: add infrastructure for calling functions on other harts
Lukas Auer
lukas.auer at aisec.fraunhofer.de
Mon Feb 11 22:13:38 UTC 2019
Harts on RISC-V boot independently and U-Boot is responsible for
managing them. Functions are called on other harts with
smp_call_function(), which sends inter-processor interrupts (IPIs) to
all other harts. Functions are specified with their address and two
function arguments (argument 2 and 3). The first function argument is
always the hart ID of the hart calling the function. On the other harts,
the IPI interrupt handler handle_ipi() must be called on software
interrupts to handle the request and call the specified function.
Functions are stored in the ipi_data data structure. Every hart has its
own data structure in global data. While this is not required at the
moment (all harts are expected to boot Linux), this does allow future
expansion, where other harts may be used for monitoring or other tasks.
Signed-off-by: Lukas Auer <lukas.auer at aisec.fraunhofer.de>
---
arch/riscv/Kconfig | 19 +++++
arch/riscv/include/asm/global_data.h | 5 ++
arch/riscv/include/asm/smp.h | 53 +++++++++++++
arch/riscv/lib/Makefile | 1 +
arch/riscv/lib/smp.c | 110 +++++++++++++++++++++++++++
5 files changed, 188 insertions(+)
create mode 100644 arch/riscv/include/asm/smp.h
create mode 100644 arch/riscv/lib/smp.c
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index c45e4d73a8..c0842178dd 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -116,4 +116,23 @@ config RISCV_RDTIME
config SYS_MALLOC_F_LEN
default 0x1000
+config SMP
+ bool "Symmetric Multi-Processing"
+ help
+ This enables support for systems with more than one CPU. If
+ you say N here, U-Boot will run on single and multiprocessor
+ machines, but will use only one CPU of a multiprocessor
+ machine. If you say Y here, U-Boot will run on many, but not
+ all, single processor machines.
+
+config NR_CPUS
+ int "Maximum number of CPUs (2-32)"
+ range 2 32
+ depends on SMP
+ default "8"
+ help
+ On multiprocessor machines, U-Boot sets up a stack for each CPU.
+ Stack memory is pre-allocated. U-Boot must therefore know the
+ maximum number of CPUs that may be present.
+
endmenu
diff --git a/arch/riscv/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
index a3a342c6e1..23a5f35af5 100644
--- a/arch/riscv/include/asm/global_data.h
+++ b/arch/riscv/include/asm/global_data.h
@@ -10,12 +10,17 @@
#ifndef __ASM_GBL_DATA_H
#define __ASM_GBL_DATA_H
+#include <asm/smp.h>
+
/* Architecture-specific global data */
struct arch_global_data {
long boot_hart; /* boot hart id */
#ifdef CONFIG_SIFIVE_CLINT
void __iomem *clint; /* clint base address */
#endif
+#ifdef CONFIG_SMP
+ struct ipi_data ipi[CONFIG_NR_CPUS];
+#endif
};
#include <asm-generic/global_data.h>
diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
new file mode 100644
index 0000000000..bc863fdbaf
--- /dev/null
+++ b/arch/riscv/include/asm/smp.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 Fraunhofer AISEC,
+ * Lukas Auer <lukas.auer at aisec.fraunhofer.de>
+ */
+
+#ifndef _ASM_RISCV_SMP_H
+#define _ASM_RISCV_SMP_H
+
+/**
+ * struct ipi_data - Inter-processor interrupt (IPI) data structure
+ *
+ * IPIs are used for SMP support to communicate to other harts what function to
+ * call. Functions are in the form
+ * void (*addr)(ulong hart, ulong arg0, ulong arg1).
+ *
+ * The function address and the two arguments, arg0 and arg1, are stored in the
+ * IPI data structure. The hart ID is inserted by the hart handling the IPI and
+ * calling the function.
+ *
+ * @addr: Address of function
+ * @arg0: First argument of function
+ * @arg1: Second argument of function
+ */
+struct ipi_data {
+ ulong addr;
+ ulong arg0;
+ ulong arg1;
+};
+
+/**
+ * handle_ipi() - interrupt handler for software interrupts
+ *
+ * The IPI interrupt handler must be called to handle software interrupts. It
+ * calls the function specified in the hart's IPI data structure.
+ *
+ * @hart: Hart ID of the current hart
+ */
+void handle_ipi(ulong hart);
+
+/**
+ * smp_call_function() - Call a function on all other harts
+ *
+ * Send IPIs with the specified function call to all harts.
+ *
+ * @addr: Address of function
+ * @arg0: First argument of function
+ * @arg1: Second argument of function
+ * @return 0 if OK, -ve on error
+ */
+int smp_call_function(ulong addr, ulong arg0, ulong arg1);
+
+#endif
diff --git a/arch/riscv/lib/Makefile b/arch/riscv/lib/Makefile
index edfa61690c..19370f9749 100644
--- a/arch/riscv/lib/Makefile
+++ b/arch/riscv/lib/Makefile
@@ -14,6 +14,7 @@ obj-$(CONFIG_SIFIVE_CLINT) += sifive_clint.o
obj-y += interrupts.o
obj-y += reset.o
obj-y += setjmp.o
+obj-$(CONFIG_SMP) += smp.o
# For building EFI apps
CFLAGS_$(EFI_CRT0) := $(CFLAGS_EFI)
diff --git a/arch/riscv/lib/smp.c b/arch/riscv/lib/smp.c
new file mode 100644
index 0000000000..1266a2a0ef
--- /dev/null
+++ b/arch/riscv/lib/smp.c
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 Fraunhofer AISEC,
+ * Lukas Auer <lukas.auer at aisec.fraunhofer.de>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <asm/barrier.h>
+#include <asm/smp.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+/**
+ * riscv_send_ipi() - Send inter-processor interrupt (IPI)
+ *
+ * Platform code must provide this function.
+ *
+ * @hart: Hart ID of receiving hart
+ * @return 0 if OK, -ve on error
+ */
+extern int riscv_send_ipi(int hart);
+
+/**
+ * riscv_clear_ipi() - Clear inter-processor interrupt (IPI)
+ *
+ * Platform code must provide this function.
+ *
+ * @hart: Hart ID of hart to be cleared
+ * @return 0 if OK, -ve on error
+ */
+extern int riscv_clear_ipi(int hart);
+
+static int send_ipi_many(struct ipi_data *ipi)
+{
+ ofnode node, cpus;
+ u32 reg;
+ int ret;
+
+ cpus = ofnode_path("/cpus");
+ if (!ofnode_valid(cpus)) {
+ pr_err("Can't find cpus node!\n");
+ return -EINVAL;
+ }
+
+ ofnode_for_each_subnode(node, cpus) {
+ if (!ofnode_is_available(node))
+ continue;
+
+ /* read hart ID of CPU */
+ ret = ofnode_read_u32(node, "reg", ®);
+ if (ret)
+ continue;
+
+ /* skip if it is the hart we are running on */
+ if (reg == gd->arch.boot_hart)
+ continue;
+
+ if (reg >= CONFIG_NR_CPUS) {
+ pr_err("Hart ID %d is out of range, increase CONFIG_NR_CPUS\n",
+ reg);
+ continue;
+ }
+
+ gd->arch.ipi[reg].addr = ipi->addr;
+ gd->arch.ipi[reg].arg0 = ipi->arg0;
+ gd->arch.ipi[reg].arg1 = ipi->arg1;
+ mb();
+
+ ret = riscv_send_ipi(reg);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+void handle_ipi(ulong hart)
+{
+ int ret;
+ void (*smp_function)(ulong hart, ulong arg0, ulong arg1);
+
+ if (hart >= CONFIG_NR_CPUS)
+ return;
+
+ ret = riscv_clear_ipi(hart);
+ if (ret) {
+ pr_err("Cannot clear IPI\n");
+ return;
+ }
+
+ smp_function = (void (*)(ulong, ulong, ulong))gd->arch.ipi[hart].addr;
+ invalidate_icache_all();
+
+ smp_function(hart, gd->arch.ipi[hart].arg0, gd->arch.ipi[hart].arg1);
+}
+
+int smp_call_function(ulong addr, ulong arg0, ulong arg1)
+{
+ int ret = 0;
+ struct ipi_data ipi;
+
+ ipi.addr = addr;
+ ipi.arg0 = arg0;
+ ipi.arg1 = arg1;
+
+ ret = send_ipi_many(&ipi);
+
+ return ret;
+}
--
2.20.1
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