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authorDamien Le Moal <damien.lemoal@wdc.com>2020-03-16 09:47:38 +0900
committerPalmer Dabbelt <palmerdabbelt@google.com>2020-04-03 10:46:43 -0700
commit335b139057ef79dbede01dea6e8c3f47c2b88802 (patch)
treea00fb4785ff526dbca683b360e2239cad46c7487 /arch/riscv/kernel
parent956d705dd279f70d5a222375fa97b637d6e8c43d (diff)
riscv: Add SOC early init support
Add a mechanism for early SoC initialization for platforms that need additional hardware initialization not possible through the regular device tree and drivers mechanism. With this, a SoC specific initialization function can be called very early, before DTB parsing is done by parse_dtb() in Linux RISC-V kernel setup code. This can be very useful for early hardware initialization for No-MMU kernels booted directly in M-mode because it is quite likely that no other booting stage exist prior to the No-MMU kernel. Example use of a SoC early initialization is as follows: static void vendor_abc_early_init(const void *fdt) { /* * some early init code here that can use simple matches * against the flat device tree file. */ } SOC_EARLY_INIT_DECLARE("vendor,abc", abc_early_init); This early initialization function is executed only if the flat device tree for the board has a 'compatible = "vendor,abc"' entry; Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com> Signed-off-by: Anup Patel <anup.patel@wdc.com> Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv/kernel')
-rw-r--r--arch/riscv/kernel/Makefile1
-rw-r--r--arch/riscv/kernel/head.S1
-rw-r--r--arch/riscv/kernel/soc.c28
-rw-r--r--arch/riscv/kernel/vmlinux.lds.S6
4 files changed, 36 insertions, 0 deletions
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 1bad93f63dba..86c83081044f 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -11,6 +11,7 @@ endif
extra-y += head.o
extra-y += vmlinux.lds
+obj-y += soc.o
obj-y += cpu.o
obj-y += cpufeature.o
obj-y += entry.o
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index e5115d5e0b3a..98a406474e7d 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -234,6 +234,7 @@ clear_bss_done:
call kasan_early_init
#endif
/* Start the kernel */
+ call soc_early_init
call parse_dtb
tail start_kernel
diff --git a/arch/riscv/kernel/soc.c b/arch/riscv/kernel/soc.c
new file mode 100644
index 000000000000..0b3b3dc9ad0f
--- /dev/null
+++ b/arch/riscv/kernel/soc.c
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2020 Western Digital Corporation or its affiliates.
+ */
+#include <linux/init.h>
+#include <linux/libfdt.h>
+#include <asm/pgtable.h>
+#include <asm/soc.h>
+
+/*
+ * This is called extremly early, before parse_dtb(), to allow initializing
+ * SoC hardware before memory or any device driver initialization.
+ */
+void __init soc_early_init(void)
+{
+ void (*early_fn)(const void *fdt);
+ const struct of_device_id *s;
+ const void *fdt = dtb_early_va;
+
+ for (s = (void *)&__soc_early_init_table_start;
+ (void *)s < (void *)&__soc_early_init_table_end; s++) {
+ if (!fdt_node_check_compatible(fdt, 0, s->compatible)) {
+ early_fn = s->data;
+ early_fn(fdt);
+ return;
+ }
+ }
+}
diff --git a/arch/riscv/kernel/vmlinux.lds.S b/arch/riscv/kernel/vmlinux.lds.S
index 435cd60dca04..0339b6bbe11a 100644
--- a/arch/riscv/kernel/vmlinux.lds.S
+++ b/arch/riscv/kernel/vmlinux.lds.S
@@ -28,6 +28,12 @@ SECTIONS
__init_begin = .;
INIT_TEXT_SECTION(PAGE_SIZE)
INIT_DATA_SECTION(16)
+ . = ALIGN(8);
+ __soc_early_init_table : {
+ __soc_early_init_table_start = .;
+ KEEP(*(__soc_early_init_table))
+ __soc_early_init_table_end = .;
+ }
/* we have to discard exit text and such at runtime, not link time */
.exit.text :
{