openwrtv3/target/linux/brcm47xx/patches-3.10/080-MIPS-Add-8250-16550-serial-early-printk-driver.patch
Hauke Mehrtens b201818044 brcm47xx: update early printk patches
Early printk was disabled because it caused hangs on some devices, the
old patches were using the CFE console now we use the normal serial
console, it is at a constant address.

Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>

SVN-Revision: 38309
2013-10-06 23:55:35 +00:00

124 lines
3.8 KiB
Diff

commit 0a76092a63809a0e72e3e9552acadf42869c0293
Author: Yoichi Yuasa <yuasa@linux-mips.org>
Date: Mon Feb 8 20:59:39 2010 +0900
MIPS: Add 8250/16550 serial early printk driver
Signed-off-by: Yoichi Yuasa <yuasa@linux-mips.org>
Cc: linux-mips <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/947/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
--- a/arch/mips/Kconfig.debug
+++ b/arch/mips/Kconfig.debug
@@ -20,6 +20,14 @@ config EARLY_PRINTK
doesn't cooperate with an X server. You should normally say N here,
unless you want to debug such a crash.
+config EARLY_PRINTK_8250
+ bool "8250/16550 and compatible serial early printk driver"
+ depends on EARLY_PRINTK
+ default n
+ help
+ If you say Y here, it will be possible to use a 8250/16550 serial
+ port as the boot console.
+
config CMDLINE_BOOL
bool "Built-in kernel command line"
default n
--- a/arch/mips/include/asm/setup.h
+++ b/arch/mips/include/asm/setup.h
@@ -5,6 +5,14 @@
extern void setup_early_printk(void);
+#ifdef CONFIG_EARLY_PRINTK_8250
+extern void setup_8250_early_printk_port(unsigned long base,
+ unsigned int reg_shift, unsigned int timeout);
+#else
+static inline void setup_8250_early_printk_port(unsigned long base,
+ unsigned int reg_shift, unsigned int timeout) {}
+#endif
+
extern void set_handler(unsigned long offset, void *addr, unsigned long len);
extern void set_uncached_handler(unsigned long offset, void *addr, unsigned long len);
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -84,6 +84,7 @@ obj-$(CONFIG_GPIO_TXX9) += gpio_txx9.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
+obj-$(CONFIG_EARLY_PRINTK_8250) += early_printk_8250.o
obj-$(CONFIG_SPINLOCK_TEST) += spinlock_test.o
obj-$(CONFIG_MIPS_MACHINE) += mips_machine.o
--- /dev/null
+++ b/arch/mips/kernel/early_printk_8250.c
@@ -0,0 +1,66 @@
+/*
+ * 8250/16550-type serial ports prom_putchar()
+ *
+ * Copyright (C) 2010 Yoichi Yuasa <yuasa@linux-mips.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+#include <linux/io.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+
+static void __iomem *serial8250_base;
+static unsigned int serial8250_reg_shift;
+static unsigned int serial8250_tx_timeout;
+
+void setup_8250_early_printk_port(unsigned long base, unsigned int reg_shift,
+ unsigned int timeout)
+{
+ serial8250_base = (void __iomem *)base;
+ serial8250_reg_shift = reg_shift;
+ serial8250_tx_timeout = timeout;
+}
+
+static inline u8 serial_in(int offset)
+{
+ return readb(serial8250_base + (offset << serial8250_reg_shift));
+}
+
+static inline void serial_out(int offset, char value)
+{
+ writeb(value, serial8250_base + (offset << serial8250_reg_shift));
+}
+
+void prom_putchar(char c)
+{
+ unsigned int timeout;
+ int status, bits;
+
+ if (!serial8250_base)
+ return;
+
+ timeout = serial8250_tx_timeout;
+ bits = UART_LSR_TEMT | UART_LSR_THRE;
+
+ do {
+ status = serial_in(UART_LSR);
+
+ if (--timeout == 0)
+ break;
+ } while ((status & bits) != bits);
+
+ if (timeout)
+ serial_out(UART_TX, c);
+}