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Subject[PATCH 1/3] riscv: Support for early console.
Date
This feature is mainly used for debugging during the early startup
process. Currently, the implementation of this function is based
on the sbi interface.

By setting the CONFIG_RISCV_EARLY_CONSOLE option, this
function can be enabled, which subsequently sets the log level
to CONSOLE_LOGLEVEL_MOTORMOUT.

Signed-off-by: Jinglin Wen <jinglin.wen@shingroup.cn>
---
arch/riscv/include/asm/early_console.h | 23 ++++++
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/early_console.c | 108 +++++++++++++++++++++++++
arch/riscv/kernel/setup.c | 2 +
4 files changed, 134 insertions(+)
create mode 100644 arch/riscv/include/asm/early_console.h
create mode 100644 arch/riscv/kernel/early_console.c

diff --git a/arch/riscv/include/asm/early_console.h b/arch/riscv/include/asm/early_console.h
new file mode 100644
index 000000000000..0683a42e9207
--- /dev/null
+++ b/arch/riscv/include/asm/early_console.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+#ifndef _ASM_EARLY_CONSOLE_H
+#define _ASM_EARLY_CONSOLE_H
+#ifdef __KERNEL__
+
+#include <linux/compiler.h>
+#include <linux/init.h>
+
+void __init early_console_init(void);
+
+/* early_console libs */
+void early_console_puts(const char *s);
+int early_console_write(const char *s, int n);
+void early_console_printf(const char *fmt, ...);
+void early_console_progress(char *s, unsigned short hex);
+
+#ifdef CONFIG_RISCV_EARLY_CONSOLE_SBI
+void __init hvc_sbi_early_init(void (**putc)(char c));
+#endif /* CONFIG_HVC_RISCV_SBI */
+
+#endif /* __KERNEL__ */
+#endif /* _ASM_EARLY_CONSOLE_H */
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index 81d94a8ee10f..ef037e3762f1 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -48,6 +48,7 @@ obj-y += ptrace.o
obj-y += reset.o
obj-y += return_address.o
obj-y += setup.o
+obj-y += early_console.o
obj-y += signal.o
obj-y += syscall_table.o
obj-y += sys_riscv.o
diff --git a/arch/riscv/kernel/early_console.c b/arch/riscv/kernel/early_console.c
new file mode 100644
index 000000000000..64f3a5705413
--- /dev/null
+++ b/arch/riscv/kernel/early_console.c
@@ -0,0 +1,108 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Early console support for RISCV
+ */
+
+#include <linux/stdarg.h>
+#include <linux/types.h>
+#include <linux/console.h>
+#include <asm/sbi.h>
+#include <asm/early_console.h>
+
+/* interface for early console output characters */
+void (*riscv_early_console_putc)(char c);
+
+void early_console_puts(const char *s)
+{
+ if (riscv_early_console_putc) {
+ char c;
+
+ if (s && *s != '\0') {
+ while ((c = *s++) != '\0')
+ riscv_early_console_putc(c);
+ }
+ }
+}
+
+int early_console_write(const char *s, int n)
+{
+ int remain = n;
+ char c;
+
+ if (!riscv_early_console_putc)
+ return 0;
+
+ if (s && *s != '\0') {
+ while (((c = *s++) != '\0') && (remain-- > 0))
+ riscv_early_console_putc(c);
+ }
+
+ return n - remain;
+}
+
+#define EARLY_CONSOLE_BUFSIZE 256
+void early_console_printf(const char *fmt, ...)
+{
+ if (riscv_early_console_putc) {
+ char buf[EARLY_CONSOLE_BUFSIZE];
+ va_list args;
+
+ va_start(args, fmt);
+ vsnprintf(buf, EARLY_CONSOLE_BUFSIZE, fmt, args);
+ early_console_puts(buf);
+ va_end(args);
+ }
+}
+
+void __init early_console_progress(char *s, unsigned short hex)
+{
+ early_console_puts(s);
+ early_console_puts("\n");
+}
+
+/*
+ * Console based on early console
+ */
+static void riscv_early_console_write(struct console *con, const char *s,
+ unsigned int n)
+{
+ early_console_write(s, n);
+}
+
+static struct console riscv_early_console = {
+ .name = "riscv_early_con",
+ .write = riscv_early_console_write,
+ .flags = CON_PRINTBUFFER | CON_ENABLED | CON_BOOT | CON_ANYTIME,
+ .index = 0,
+};
+
+static void __init register_early_console(void)
+{
+ if (!riscv_early_console_putc)
+ return;
+
+ add_preferred_console("riscv_early_con", 0, NULL);
+ register_console(&riscv_early_console);
+}
+
+/*
+ * This is called after sbi_init.
+ */
+void __init early_console_init(void)
+{
+ /*
+ * Set riscv_early_console_putc.
+ * If there are other output interfaces, you can add corresponding code
+ * to initialize riscv_early_console_putc.
+ */
+#if defined(CONFIG_RISCV_EARLY_CONSOLE_SBI)
+ /* using the sbi */
+ hvc_sbi_early_init(&riscv_early_console_putc);
+#else
+ /* using other */
+#endif
+
+ console_loglevel = CONSOLE_LOGLEVEL_MOTORMOUTH;
+ register_early_console();
+}
+
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 4f73c0ae44b2..1b48630f0861 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -36,6 +36,7 @@
#include <asm/thread_info.h>
#include <asm/kasan.h>
#include <asm/efi.h>
+#include <asm/early_console.h>

#include "head.h"

@@ -255,6 +256,7 @@ void __init setup_arch(char **cmdline_p)

early_ioremap_setup();
sbi_init();
+ early_console_init();
jump_label_init();
parse_early_param();

--
2.25.1

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