[ARM] Provide a method to alter the control register (47fd7052) · Commits · 戴 / test

i.MX needs to tweak the control register to support CPU frequency scaling. Rather than have folk blindly try and change the control register by writing to it and then wondering why it doesn't work, provide a method (which is safe for UP only, and therefore only available for UP) to achieve this. Signed-off-by:

Russell King <rmk+kernel@arm.linux.org.uk>

include/asm-arm/system.h

+20 −0

Original line number	Diff line number	Diff line
		@@ -173,6 +173,26 @@ static inline void set_copro_access(unsigned int val)
		extern unsigned long cr_no_alignment; /* defined in entry-armv.S */
		extern unsigned long cr_alignment; /* defined in entry-armv.S */

		#ifndef CONFIG_SMP
		static inline void adjust_cr(unsigned long mask, unsigned long set)
		{
		unsigned long flags, cr;

		mask &= ~CR_A;

		set &= mask;

		local_irq_save(flags);

		cr_no_alignment = (cr_no_alignment & ~mask) \| set;
		cr_alignment = (cr_alignment & ~mask) \| set;

		set_cr((get_cr() & ~mask) \| set);

		local_irq_restore(flags);
		}
		#endif

		#define UDBG_UNDEFINED (1 << 0)
		#define UDBG_SYSCALL (1 << 1)
		#define UDBG_BADABORT (1 << 2)

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