system.h

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#ifndef __ASM_ARM_SYSTEM_H
#define __ASM_ARM_SYSTEM_H

#ifdef __KERNEL__

#include <linux/config.h>

#define CPU_ARCH_UNKNOWN	0
#define CPU_ARCH_ARMv3		1
#define CPU_ARCH_ARMv4		2
#define CPU_ARCH_ARMv4T		3
#define CPU_ARCH_ARMv5		4
#define CPU_ARCH_ARMv5T		5
#define CPU_ARCH_ARMv5TE	6
#define CPU_ARCH_ARMv5TEJ	7
#define CPU_ARCH_ARMv6		8

/*
 * CR1 bits (CP#15 CR1)
 */
#define CR_M	(1 << 0)	/* MMU enable				*/
#define CR_A	(1 << 1)	/* Alignment abort enable		*/
#define CR_C	(1 << 2)	/* Dcache enable			*/
#define CR_W	(1 << 3)	/* Write buffer enable			*/
#define CR_P	(1 << 4)	/* 32-bit exception handler		*/
#define CR_D	(1 << 5)	/* 32-bit data address range		*/
#define CR_L	(1 << 6)	/* Implementation defined		*/
#define CR_B	(1 << 7)	/* Big endian				*/
#define CR_S	(1 << 8)	/* System MMU protection		*/
#define CR_R	(1 << 9)	/* ROM MMU protection			*/
#define CR_F	(1 << 10)	/* Implementation defined		*/
#define CR_Z	(1 << 11)	/* Implementation defined		*/
#define CR_I	(1 << 12)	/* Icache enable			*/
#define CR_V	(1 << 13)	/* Vectors relocated to 0xffff0000	*/
#define CR_RR	(1 << 14)	/* Round Robin cache replacement	*/
#define CR_L4	(1 << 15)	/* LDR pc can set T bit			*/
#define CR_DT	(1 << 16)
#define CR_IT	(1 << 18)
#define CR_ST	(1 << 19)
#define CR_FI	(1 << 21)	/* Fast interrupt (lower latency mode)	*/
#define CR_U	(1 << 22)	/* Unaligned access operation		*/
#define CR_XP	(1 << 23)	/* Extended page tables			*/
#define CR_VE	(1 << 24)	/* Vectored interrupts			*/

#define CPUID_ID	0
#define CPUID_CACHETYPE	1
#define CPUID_TCM	2
#define CPUID_TLBTYPE	3

#define read_cpuid(reg)							\
	({								\
		unsigned int __val;					\
		asm("mrc	p15, 0, %0, c0, c0, " __stringify(reg)	\
		    : "=r" (__val)					\
		    :							\
		    : "cc");						\
		__val;							\
	})

/*
 * This is used to ensure the compiler did actually allocate the register we
 * asked it for some inline assembly sequences.  Apparently we can't trust
 * the compiler from one version to another so a bit of paranoia won't hurt.
 * This string is meant to be concatenated with the inline asm string and
 * will cause compilation to stop on mismatch.
 * (for details, see gcc PR 15089)
 */
#define __asmeq(x, y)  ".ifnc " x "," y " ; .err ; .endif\n\t"

#ifndef __ASSEMBLY__

#include <linux/linkage.h>

struct thread_info;
struct task_struct;

/* information about the system we're running on */
extern unsigned int system_rev;
extern unsigned int system_serial_low;
extern unsigned int system_serial_high;
extern unsigned int mem_fclk_21285;

struct pt_regs;

void die(const char *msg, struct pt_regs *regs, int err)
		__attribute__((noreturn));

void die_if_kernel(const char *str, struct pt_regs *regs, int err);

void hook_fault_code(int nr, int (*fn)(unsigned long, unsigned int,
				       struct pt_regs *),
		     int sig, const char *name);

#include <asm/proc-fns.h>

#define xchg(ptr,x) \
	((__typeof__(*(ptr)))__xchg((unsigned long)(x),(ptr),sizeof(*(ptr))))

#define tas(ptr) (xchg((ptr),1))

extern asmlinkage void __backtrace(void);

extern int cpu_architecture(void);

#define set_cr(x)					\
	__asm__ __volatile__(				\
	"mcr	p15, 0, %0, c1, c0, 0	@ set CR"	\
	: : "r" (x) : "cc")

#define get_cr()					\
	({						\
	unsigned int __val;				\
	__asm__ __volatile__(				\
	"mrc	p15, 0, %0, c1, c0, 0	@ get CR"	\
	: "=r" (__val) : : "cc");			\
	__val;						\
	})

extern unsigned long cr_no_alignment;	/* defined in entry-armv.S */
extern unsigned long cr_alignment;	/* defined in entry-armv.S */

#define UDBG_UNDEFINED	(1 << 0)
#define UDBG_SYSCALL	(1 << 1)
#define UDBG_BADABORT	(1 << 2)
#define UDBG_SEGV	(1 << 3)
#define UDBG_BUS	(1 << 4)

extern unsigned int user_debug;

#if __LINUX_ARM_ARCH__ >= 4
#define vectors_high()	(cr_alignment & CR_V)
#else
#define vectors_high()	(0)
#endif

#define mb() __asm__ __volatile__ ("" : : : "memory")
#define rmb() mb()
#define wmb() mb()
#define read_barrier_depends() do { } while(0)
#define set_mb(var, value)  do { var = value; mb(); } while (0)
#define set_wmb(var, value) do { var = value; wmb(); } while (0)
#define nop() __asm__ __volatile__("mov\tr0,r0\t@ nop\n\t");

#ifdef CONFIG_SMP
/*
 * Define our own context switch locking.  This allows us to enable
 * interrupts over the context switch, otherwise we end up with high
 * interrupt latency.  The real problem area is switch_mm() which may
 * do a full cache flush.
 */
#define prepare_arch_switch(rq,next)					\
do {									\
	spin_lock(&(next)->switch_lock);				\
	spin_unlock_irq(&(rq)->lock);					\
} while (0)

#define finish_arch_switch(rq,prev)					\
	spin_unlock(&(prev)->switch_lock)

#define task_running(rq,p)						\
	((rq)->curr == (p) || spin_is_locked(&(p)->switch_lock))
#else
/*
 * Our UP-case is more simple, but we assume knowledge of how
 * spin_unlock_irq() and friends are implemented.  This avoids
 * us needlessly decrementing and incrementing the preempt count.
 */
#define prepare_arch_switch(rq,next)	local_irq_enable()
#define finish_arch_switch(rq,prev)	spin_unlock(&(rq)->lock)
#define task_running(rq,p)		((rq)->curr == (p))
#endif

/*
 * switch_to(prev, next) should switch from task `prev' to `next'
 * `prev' will never be the same as `next'.  schedule() itself
 * contains the memory barrier to tell GCC not to cache `current'.
 */
extern struct task_struct *__switch_to(struct task_struct *, struct thread_info *, struct thread_info *);

#define switch_to(prev,next,last)					\
do {									\
	last = __switch_to(prev,prev->thread_info,next->thread_info);	\
} while (0)

/*
 * CPU interrupt mask handling.
 */
#if __LINUX_ARM_ARCH__ >= 6

#define local_irq_save(x)					\
	({							\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_irq_save\n"	\
	"cpsid	i"						\
	: "=r" (x) : : "memory", "cc");				\
	})

#define local_irq_enable()  __asm__("cpsie i	@ __sti" : : : "memory", "cc")
#define local_irq_disable() __asm__("cpsid i	@ __cli" : : : "memory", "cc")
#define local_fiq_enable()  __asm__("cpsie f	@ __stf" : : : "memory", "cc")
#define local_fiq_disable() __asm__("cpsid f	@ __clf" : : : "memory", "cc")

#else

/*
 * Save the current interrupt enable state & disable IRQs
 */
#define local_irq_save(x)					\
	({							\
		unsigned long temp;				\
		(void) (&temp == &x);				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_irq_save\n"	\
"	orr	%1, %0, #128\n"					\
"	msr	cpsr_c, %1"					\
	: "=r" (x), "=r" (temp)					\
	:							\
	: "memory", "cc");					\
	})
	
/*
 * Enable IRQs
 */
#define local_irq_enable()					\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_irq_enable\n"	\
"	bic	%0, %0, #128\n"					\
"	msr	cpsr_c, %0"					\
	: "=r" (temp)						\
	:							\
	: "memory", "cc");					\
	})

/*
 * Disable IRQs
 */
#define local_irq_disable()					\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_irq_disable\n"	\
"	orr	%0, %0, #128\n"					\
"	msr	cpsr_c, %0"					\
	: "=r" (temp)						\
	:							\
	: "memory", "cc");					\
	})

/*
 * Enable FIQs
 */
#define local_fiq_enable()					\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ stf\n"		\
"	bic	%0, %0, #64\n"					\
"	msr	cpsr_c, %0"					\
	: "=r" (temp)						\
	:							\
	: "memory", "cc");					\
	})

/*
 * Disable FIQs
 */
#define local_fiq_disable()					\
	({							\
		unsigned long temp;				\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ clf\n"		\
"	orr	%0, %0, #64\n"					\
"	msr	cpsr_c, %0"					\
	: "=r" (temp)						\
	:							\
	: "memory", "cc");					\
	})

#endif

/*
 * Save the current interrupt enable state.
 */
#define local_save_flags(x)					\
	({							\
	__asm__ __volatile__(					\
	"mrs	%0, cpsr		@ local_save_flags"	\
	: "=r" (x) : : "memory", "cc");				\
	})

/*
 * restore saved IRQ & FIQ state
 */
#define local_irq_restore(x)					\
	__asm__ __volatile__(					\
	"msr	cpsr_c, %0		@ local_irq_restore\n"	\
	:							\
	: "r" (x)						\
	: "memory", "cc")

#define irqs_disabled()			\
({					\
	unsigned long flags;		\
	local_save_flags(flags);	\
	flags & PSR_I_BIT;		\
})

#ifdef CONFIG_SMP
#error SMP not supported

#define smp_mb()		mb()
#define smp_rmb()		rmb()
#define smp_wmb()		wmb()
#define smp_read_barrier_depends()		read_barrier_depends()

#else

#define smp_mb()		barrier()
#define smp_rmb()		barrier()
#define smp_wmb()		barrier()
#define smp_read_barrier_depends()		do { } while(0)

#if defined(CONFIG_CPU_SA1100) || defined(CONFIG_CPU_SA110)
/*
 * On the StrongARM, "swp" is terminally broken since it bypasses the
 * cache totally.  This means that the cache becomes inconsistent, and,
 * since we use normal loads/stores as well, this is really bad.
 * Typically, this causes oopsen in filp_close, but could have other,
 * more disasterous effects.  There are two work-arounds:
 *  1. Disable interrupts and emulate the atomic swap
 *  2. Clean the cache, perform atomic swap, flush the cache
 *
 * We choose (1) since its the "easiest" to achieve here and is not
 * dependent on the processor type.
 */
#define swp_is_buggy
#endif

static inline unsigned long __xchg(unsigned long x, volatile void *ptr, int size)
{
	extern void __bad_xchg(volatile void *, int);
	unsigned long ret;
#ifdef swp_is_buggy
	unsigned long flags;
#endif

	switch (size) {
#ifdef swp_is_buggy
		case 1:
			local_irq_save(flags);
			ret = *(volatile unsigned char *)ptr;
			*(volatile unsigned char *)ptr = x;
			local_irq_restore(flags);
			break;

		case 4:
			local_irq_save(flags);
			ret = *(volatile unsigned long *)ptr;
			*(volatile unsigned long *)ptr = x;
			local_irq_restore(flags);
			break;
#else
		case 1:	__asm__ __volatile__ ("swpb %0, %1, [%2]"
					: "=&r" (ret)
					: "r" (x), "r" (ptr)
					: "memory", "cc");
			break;
		case 4:	__asm__ __volatile__ ("swp %0, %1, [%2]"
					: "=&r" (ret)
					: "r" (x), "r" (ptr)
					: "memory", "cc");
			break;
#endif
		default: __bad_xchg(ptr, size), ret = 0;
	}

	return ret;
}

#endif /* CONFIG_SMP */

#endif /* __ASSEMBLY__ */

#endif /* __KERNEL__ */

#endif