From: Greentime Hu <[email protected]>
Signed-off-by: Rick Chen <[email protected]>
Signed-off-by: Greentime Hu <[email protected]>
---
arch/nds32/kernel/early_printk.c | 124 ++++++++++++++++++++++++++++++++++++++
1 file changed, 124 insertions(+)
create mode 100644 arch/nds32/kernel/early_printk.c
diff --git a/arch/nds32/kernel/early_printk.c b/arch/nds32/kernel/early_printk.c
new file mode 100644
index 0000000..269c3cd
--- /dev/null
+++ b/arch/nds32/kernel/early_printk.c
@@ -0,0 +1,124 @@
+/*
+ * Copyright (C) 2005-2017 Andes Technology Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/console.h>
+#include <linux/init.h>
+#include <linux/io.h>
+
+#include <linux/serial_reg.h>
+
+extern void __iomem *early_io_map(phys_addr_t phys);
+static void __iomem *early_base;
+static void (*printch) (char ch);
+
+/*
+ * 8250/16550 (8-bit aligned registers) single character TX.
+ */
+static void uart8250_8bit_printch(char ch)
+{
+ while (!(readb(early_base + UART_LSR) & UART_LSR_THRE)) ;
+ writeb(ch, early_base + UART_TX);
+}
+
+/*
+ * 8250/16550 (32-bit aligned registers) single character TX.
+ */
+static void uart8250_32bit_printch(char ch)
+{
+ while (!(readl(early_base + (UART_LSR << 2)) & UART_LSR_THRE)) ;
+ writel(ch, early_base + (UART_TX << 2));
+}
+
+struct earlycon_match {
+ const char *name;
+ void (*printch) (char ch);
+};
+
+static const struct earlycon_match earlycon_match[] __initconst = {
+ {.name = "uart8250-8bit",.printch = uart8250_8bit_printch,},
+ {.name = "uart8250-32bit",.printch = uart8250_32bit_printch,},
+ {}
+};
+
+static void early_write(struct console *con, const char *s, unsigned n)
+{
+ while (n-- > 0) {
+ if (*s == '\n')
+ printch('\r');
+ printch(*s);
+ s++;
+ }
+}
+
+static struct console early_console_dev = {
+ .name = "earlycon",
+ .write = early_write,
+ .flags = CON_PRINTBUFFER | CON_BOOT,
+ .index = -1,
+};
+
+/*
+ * Parse earlyprintk=... parameter in the format:
+ *
+ * <name>[,<addr>][,<options>]
+ *
+ * and register the early console. It is assumed that the UART has been
+ * initialised by the bootloader already.
+ */
+static int __init setup_early_printk(char *buf)
+{
+ const struct earlycon_match *match = earlycon_match;
+ phys_addr_t paddr = 0;
+
+ if (!buf) {
+ pr_warning("No earlyprintk arguments passed.\n");
+ return 0;
+ }
+
+ while (match->name) {
+ size_t len = strlen(match->name);
+ if (!strncmp(buf, match->name, len)) {
+ buf += len;
+ break;
+ }
+ match++;
+ }
+ if (!match->name) {
+ pr_warning("Unknown earlyprintk arguments: %s\n", buf);
+ return 0;
+ }
+
+ /* I/O address */
+ if (!strncmp(buf, ",0x", 3)) {
+ char *e;
+ paddr = simple_strtoul(buf + 1, &e, 16);
+ buf = e;
+ }
+
+ if (paddr)
+ early_base = early_io_map(paddr);
+
+ if (!strcmp(CONFIG_NDS32_BUILTIN_DTB, "ae3xx"))
+ early_base += 32;
+
+ printch = match->printch;
+ register_console(&early_console_dev);
+
+ return 0;
+}
+
+early_param("earlyprintk", setup_early_printk);
--
1.7.9.5
From 1583546507458333964@xxx Thu Nov 09 00:33:52 +0000 2017
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