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Re: [PATCH 1/2] MIPS: add 8250/16550 serial early printk driver

To: Yoichi Yuasa <yuasa@linux-mips.org>
Subject: Re: [PATCH 1/2] MIPS: add 8250/16550 serial early printk driver
From: Sergei Shtylyov <sshtylyov@mvista.com>
Date: Mon, 08 Feb 2010 12:58:08 +0300
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips <linux-mips@linux-mips.org>
In-reply-to: <20100205232857.eb65967f.yuasa@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20100205232857.eb65967f.yuasa@linux-mips.org>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Thunderbird 2.0.0.23 (Windows/20090812)
Hello.

Yoichi Yuasa wrote:

Signed-off-by: Yoichi Yuasa <yuasa@linux-mips.org>
[...]
diff --git a/arch/mips/Kconfig.debug b/arch/mips/Kconfig.debug
index 32a010d..f5d739c 100644
--- 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.
+       

  Tab not needed here.

diff --git a/arch/mips/include/asm/setup.h b/arch/mips/include/asm/setup.h
index 50511aa..7395b7f 100644
--- a/arch/mips/include/asm/setup.h
+++ b/arch/mips/include/asm/setup.h
@@ -5,6 +5,15 @@
#ifdef __KERNEL__
 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
+
 #endif /* __KERNEL__ */
#endif /* __SETUP_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 9326af5..03fc037 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -93,6 +93,7 @@ obj-$(CONFIG_GPIO_TXX9)               += gpio_txx9.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o
 obj-$(CONFIG_EARLY_PRINTK)     += early_printk.o
+obj-$(CONFIG_EARLY_PRINTK_8250)        += early_printk_8250.o
CFLAGS_cpu-bugs64.o = $(shell if $(CC) $(KBUILD_CFLAGS) -Wa,-mdaddi -c -o /dev/null -xc /dev/null >/dev/null 2>&1; then echo "-DHAVE_AS_SET_DADDI"; fi) diff --git a/arch/mips/kernel/early_printk_8250.c b/arch/mips/kernel/early_printk_8250.c
new file mode 100644
index 0000000..6faf8fd
--- /dev/null
+++ b/arch/mips/kernel/early_printk_8250.c
@@ -0,0 +1,68 @@
+/*
+ *  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 unsigned long 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 = base;

Why not declare 'serial8250_base' as 'void __iomem *' and only cast once, here?

WBR, Sergei


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