[IMX6Q]如何得知当前平台是IMX6Q

kernel version: 3.0.35

一般linux的通用方法是通过

kernel_imx\include\generated\mach-types.h里的定义

machine_is_mx6q_sabresd 来判断当前是否属于此平台

#ifdef CONFIG_MACH_MX6Q_SABRESD
# ifdef machine_arch_type
#  undef machine_arch_type
#  define machine_arch_type	__machine_arch_type
# else
#  define machine_arch_type	MACH_TYPE_MX6Q_SABRESD
# endif
# define machine_is_mx6q_sabresd()	(machine_arch_type == MACH_TYPE_MX6Q_SABRESD)
#else
# define machine_is_mx6q_sabresd()	(0)
#endif

因为有多个平台同时定义，所以machine_arch_type一般都是__machine_arch_type，

__machine_arch_type的定义在kernel_imx\arch\arm\kernel\head-common.S

__mmap_switched_data:
......
	.long	__machine_arch_type		@ r5
	.long	__atags_pointer			@ r6
...... 

当时系统开机之后只定义而并没有赋值，imx6q使用了读取硬件寄存器的方法：

kernel_imx\arch\arm\plat-mxc\include\mach\mxc.h

# define cpu_is_mx6q() (mxc_cpu_type == MXC_CPU_MX6Q)

kernel_imx\arch\arm\plat-mxc\cpu.c

void mxc_set_cpu_type(unsigned int type)
{
	__mxc_cpu_type = type;
}

kernel_imx\arch\arm\mach-mx6\mm.c

static void mx6_set_cpu_type(void)
{
	u32 cpu_type = readl(IO_ADDRESS(ANATOP_BASE_ADDR + 0x280));

	cpu_type >>= 16;
	if (cpu_type == 0x60) {
		mxc_set_cpu_type(MXC_CPU_MX6SL);
		imx_print_silicon_rev("i.MX6SoloLite", mx6sl_revision());
		return;
	}

	cpu_type = readl(IO_ADDRESS(ANATOP_BASE_ADDR + 0x260));
	cpu_type >>= 16;
	if (cpu_type == 0x63) {
		mxc_set_cpu_type(MXC_CPU_MX6Q);
		imx_print_silicon_rev("i.MX6Q", mx6q_revision());
	} else if (cpu_type == 0x61) {
		mxc_set_cpu_type(MXC_CPU_MX6DL);
		imx_print_silicon_rev("i.MX6DL/SOLO", mx6dl_revision());
	} else
		pr_err("Unknown CPU type: %x\n", cpu_type);
}

That's it!

Refer to: http://blog.csdn.net/sehrich/article/details/7208752