linux/arch/mips/loongson/common/setup.c
Huacai Chen 300459d558 MIPS: Loongson 3: Add Loongson-3 SMP support
IPI registers of Loongson-3 include IPI_SET, IPI_CLEAR, IPI_STATUS,
IPI_EN and IPI_MAILBOX_BUF. Each bit of IPI_STATUS indicate a type of
IPI and IPI_EN indicate whether the IPI is enabled. The sender write 1
to IPI_SET bits generate IPIs in IPI_STATUS, and receiver write 1 to
bits of IPI_CLEAR to clear IPIs. IPI_MAILBOX_BUF are used to deliver
more information about IPIs.

Why we change code in arch/mips/loongson/common/setup.c?

If without this change, when SMP configured, system cannot boot since
it hang at printk() in cgroup_init_early(). The root cause is:

console_trylock()
  \-->down_trylock(&console_sem)
    \-->raw_spin_unlock_irqrestore(&sem->lock, flags)
      \-->_raw_spin_unlock_irqrestore()(SMP/UP have different versions)
        \-->__raw_spin_unlock_irqrestore()  (following is the SMP case)
          \-->do_raw_spin_unlock()
            \-->arch_spin_unlock()
              \-->nudge_writes()
                \-->mb()
                  \-->wbflush()
                    \-->__wbflush()

In previous code __wbflush() is initialized in plat_mem_setup(), but
cgroup_init_early() is called before plat_mem_setup(). Therefore, In
this patch we make changes to avoid boot failure.

Signed-off-by: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Hongliang Tao <taohl@lemote.com>
Signed-off-by: Hua Yan <yanh@lemote.com>
Tested-by: Alex Smith <alex.smith@imgtec.com>
Reviewed-by: Alex Smith <alex.smith@imgtec.com>
Cc: John Crispin <john@phrozen.org>
Cc: Steven J. Hill <Steven.Hill@imgtec.com>
Cc: Aurelien Jarno <aurelien@aurel32.net>
Cc: linux-mips@linux-mips.org
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Zhangjin Wu <wuzhangjin@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/6638
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2014-03-31 18:17:12 +02:00

54 lines
1.2 KiB
C

/*
* Copyright (C) 2007 Lemote Inc. & Insititute of Computing Technology
* Author: Fuxin Zhang, zhangfx@lemote.com
*
* 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.
*/
#include <linux/module.h>
#include <asm/wbflush.h>
#include <loongson.h>
#ifdef CONFIG_VT
#include <linux/console.h>
#include <linux/screen_info.h>
#endif
static void wbflush_loongson(void)
{
asm(".set\tpush\n\t"
".set\tnoreorder\n\t"
".set mips3\n\t"
"sync\n\t"
"nop\n\t"
".set\tpop\n\t"
".set mips0\n\t");
}
void (*__wbflush)(void) = wbflush_loongson;
EXPORT_SYMBOL(__wbflush);
void __init plat_mem_setup(void)
{
#ifdef CONFIG_VT
#if defined(CONFIG_VGA_CONSOLE)
conswitchp = &vga_con;
screen_info = (struct screen_info) {
.orig_x = 0,
.orig_y = 25,
.orig_video_cols = 80,
.orig_video_lines = 25,
.orig_video_isVGA = VIDEO_TYPE_VGAC,
.orig_video_points = 16,
};
#elif defined(CONFIG_DUMMY_CONSOLE)
conswitchp = &dummy_con;
#endif
#endif
}