x86: define outb_pic and inb_pic to stop using outb_p and inb_p (bc0a733f) · Commits · 戴 / test

x86: define outb_pic and inb_pic to stop using outb_p and inb_p The delay between io port accesses to the PIC is now defined using outb_pic and inb_pic. This fix provides the next step, using udelay(2) to define the *PIC specific* timing requirements, rather than on bus-oriented timing, which is not well calibrated. Again, the primary reason for fixing this is to use proper delay strategy, and in particular to fix crashes that can result from using port 80 writes on machines that have resources on port 80, such as the ENE chips used by Quanta in latops it designs and sells to, e.g. HP. Signed-off-by:

David P. Reed <dpreed@reed.com> Signed-off-by:

Ingo Molnar <mingo@elte.hu>

include/asm-x86/i8259.h

+25 −2

Original line number	Diff line number	Diff line
		#ifndef __ASM_I8259_H__
		#define __ASM_I8259_H__

		#include <linux/delay.h>

		extern unsigned int cached_irq_mask;

		#define __byte(x,y) (((unsigned char *) &(y))[x])
		@@ -29,7 +31,28 @@ extern void enable_8259A_irq(unsigned int irq);
		extern void disable_8259A_irq(unsigned int irq);
		extern unsigned int startup_8259A_irq(unsigned int irq);

		#define inb_pic inb_p
		#define outb_pic outb_p
		/* the PIC may need a careful delay on some platforms, hence specific calls */
		static inline unsigned char inb_pic(unsigned int port)
		{
		unsigned char value = inb(port);

		/*
		* delay for some accesses to PIC on motherboard or in chipset
		* must be at least one microsecond, so be safe here:
		*/
		udelay(2);

		return value;
		}

		static inline void outb_pic(unsigned char value, unsigned int port)
		{
		outb(value, port);
		/*
		* delay for some accesses to PIC on motherboard or in chipset
		* must be at least one microsecond, so be safe here:
		*/
		udelay(2);
		}

		#endif /* __ASM_I8259_H__ */

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