linux_dsm_epyc7002/arch/mips/dec/prom/init.c
Maciej W. Rozycki 36de48de85 [MIPS] DECstation: Optimised early printk()
This is an optimised implementation of early printk() for the DECstation.  
After the recent conversion to a MIPS-specific generic routine using a 
character-by-character output the performance dropped significantly.  
This change reverts to the previous speed -- even at 9600 bps of the 
serial console the difference is visible with a naked eye; I presume for a 
framebuffer it is even worse (it may depend on exactly which one is used 
though).

 Additionally the change includes a fix for a problem that the old 
implementation had -- the format used would not actually limit the length 
of the string output.  This new implementation uses a local buffer to deal 
with it -- even with this additional copying it is much faster than the 
generic function.

 Plus this driver is registered much earlier than the generic one, 
allowing one to see critical messages, such as one about an incorrect CPU 
setting used, that are produced beforehand. :-)

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
2007-07-10 17:33:00 +01:00

136 lines
3.5 KiB
C

/*
* init.c: PROM library initialisation code.
*
* Copyright (C) 1998 Harald Koerfgen
* Copyright (C) 2002, 2004 Maciej W. Rozycki
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/linkage.h>
#include <linux/smp.h>
#include <linux/string.h>
#include <linux/types.h>
#include <asm/bootinfo.h>
#include <asm/cpu.h>
#include <asm/processor.h>
#include <asm/dec/prom.h>
int (*__rex_bootinit)(void);
int (*__rex_bootread)(void);
int (*__rex_getbitmap)(memmap *);
unsigned long *(*__rex_slot_address)(int);
void *(*__rex_gettcinfo)(void);
int (*__rex_getsysid)(void);
void (*__rex_clear_cache)(void);
int (*__prom_getchar)(void);
char *(*__prom_getenv)(char *);
int (*__prom_printf)(char *, ...);
int (*__pmax_open)(char*, int);
int (*__pmax_lseek)(int, long, int);
int (*__pmax_read)(int, void *, int);
int (*__pmax_close)(int);
/*
* Detect which PROM the DECSTATION has, and set the callback vectors
* appropriately.
*/
void __init which_prom(s32 magic, s32 *prom_vec)
{
/*
* No sign of the REX PROM's magic number means we assume a non-REX
* machine (i.e. we're on a DS2100/3100, DS5100 or DS5000/2xx)
*/
if (prom_is_rex(magic)) {
/*
* Set up prom abstraction structure with REX entry points.
*/
__rex_bootinit =
(void *)(long)*(prom_vec + REX_PROM_BOOTINIT);
__rex_bootread =
(void *)(long)*(prom_vec + REX_PROM_BOOTREAD);
__rex_getbitmap =
(void *)(long)*(prom_vec + REX_PROM_GETBITMAP);
__prom_getchar =
(void *)(long)*(prom_vec + REX_PROM_GETCHAR);
__prom_getenv =
(void *)(long)*(prom_vec + REX_PROM_GETENV);
__rex_getsysid =
(void *)(long)*(prom_vec + REX_PROM_GETSYSID);
__rex_gettcinfo =
(void *)(long)*(prom_vec + REX_PROM_GETTCINFO);
__prom_printf =
(void *)(long)*(prom_vec + REX_PROM_PRINTF);
__rex_slot_address =
(void *)(long)*(prom_vec + REX_PROM_SLOTADDR);
__rex_clear_cache =
(void *)(long)*(prom_vec + REX_PROM_CLEARCACHE);
} else {
/*
* Set up prom abstraction structure with non-REX entry points.
*/
__prom_getchar = (void *)PMAX_PROM_GETCHAR;
__prom_getenv = (void *)PMAX_PROM_GETENV;
__prom_printf = (void *)PMAX_PROM_PRINTF;
__pmax_open = (void *)PMAX_PROM_OPEN;
__pmax_lseek = (void *)PMAX_PROM_LSEEK;
__pmax_read = (void *)PMAX_PROM_READ;
__pmax_close = (void *)PMAX_PROM_CLOSE;
}
}
void __init prom_init(void)
{
extern void dec_machine_halt(void);
static char cpu_msg[] __initdata =
"Sorry, this kernel is compiled for a wrong CPU type!\n";
s32 argc = fw_arg0;
s32 *argv = (void *)fw_arg1;
u32 magic = fw_arg2;
s32 *prom_vec = (void *)fw_arg3;
/*
* Determine which PROM we have
* (and therefore which machine we're on!)
*/
which_prom(magic, prom_vec);
if (prom_is_rex(magic))
rex_clear_cache();
/* Register the early console. */
register_prom_console();
/* Were we compiled with the right CPU option? */
#if defined(CONFIG_CPU_R3000)
if ((current_cpu_data.cputype == CPU_R4000SC) ||
(current_cpu_data.cputype == CPU_R4400SC)) {
static char r4k_msg[] __initdata =
"Please recompile with \"CONFIG_CPU_R4x00 = y\".\n";
printk(cpu_msg);
printk(r4k_msg);
dec_machine_halt();
}
#endif
#if defined(CONFIG_CPU_R4X00)
if ((current_cpu_data.cputype == CPU_R3000) ||
(current_cpu_data.cputype == CPU_R3000A)) {
static char r3k_msg[] __initdata =
"Please recompile with \"CONFIG_CPU_R3000 = y\".\n";
printk(cpu_msg);
printk(r3k_msg);
dec_machine_halt();
}
#endif
prom_meminit(magic);
prom_identify_arch(magic);
prom_init_cmdline(argc, argv, magic);
}