Linux machine_desc 体系特征
Linux machine_desc 体系特征
一．ARM S3C2410中，linux描述其主要架构特征的是数据结构:
struct machine_desc
{
unsigned int nr; /*architecture number */
unsignedint phys_io; /* start of physical io */
unsignedint io_pg_offst; /* byte offset for io
* page tabe entry */
constchar *name; /* architecture name */
unsignedlong boot_params; /* tagged list */
unsignedint video_start; /* start of video RAM */
unsignedint video_end; /* end of video RAM */
unsignedint reserve_lp0 :1; /* never has lp0 */
unsignedint reserve_lp1 :1; /* never has lp1 */
unsignedint reserve_lp2 :1; /* never has lp2 */
unsignedint soft_reboot :1; /* soft reboot */
void (*fixup)(struct machine_desc *,
struct tag *, char **,
struct meminfo *);
void (*map_io)(void);/* IO mappingfunction */
void (*init_irq)(void);
structsys_timer *timer; /* system tick timer */
void (*init_machine)(void);
}
二．用到的宏
#define MACHINE_START(_type,_name) \//suyi mach-smdk2410.c
static const struct machine_desc __mach_desc_##_type \
__used \
__attribute__((__section__(".arch.info.init")))= { \
.nr = MACH_TYPE_##_type, \
.name = _name,
#define MACHINE_END \
};
三．S3C2410的linux-2.6.26.5上的具体实现
MACHINE_START(SMDK2410,"SMDK2410")
.phys_io = S3C2410_PA_UART, //串口物理地址
.io_pg_offst = (((u32)S3C24XX_VA_UART) >> 18) & 0xfffc,
.boot_params = S3C2410_SDRAM_PA+ 0x100,// u-boot传入的参数的地址
.map_io = smdk2410_map_io,
.init_irq = s3c24xx_init_irq,
.init_machine = smdk2410_init,
.timer = &s3c24xx_timer,
MACHINE_END
3.1 map_io
setup_arch-> paging_init ->devicemaps_init
|------ mdesc->map_io();
static void __init smdk2410_map_io(void)
{
s3c24xx_init_io(smdk2410_iodesc,ARRAY_SIZE(smdk2410_iodesc));//IO静态映射
s3c24xx_init_clocks(0); //时钟初始化
s3c24xx_init_uarts(smdk2410_uartcfgs,ARRAY_SIZE(smdk2410_uartcfgs));
}
3.2 init_irq
Setup_arch()
{
………
init_arch_irq =mdesc->init_irq;
system_timer =mdesc->timer;
init_machine =mdesc->init_machine;
………
}
void __init init_IRQ(void)//在start_kernel()中调用
{
……..
init_arch_irq()
……..
}
3.3 init_machine
static void (*init_machine)(void)__initdata;
static int __init customize_machine(void) {
if(init_machine)
init_machine();
return0;
}
arch_initcall(customize_machine);
在do_basic_setup()
|-------do_initcalls()中调用
static void __initsmdk2410_init(void)
{
s3c24xx_fb_set_platdata(&smdk2410_fb_info);
platform_add_devices(smdk2410_devices, ARRAY_SIZE(smdk2410_devices));
//初始化平台设备
smdk_machine_init();
}
3.4 timer
void __init time_init(void)//在start_kernel()中调用，初始化时钟
{
………….
system_timer->init();
………….
}