#ifndef _MC6821_H_#define _MC6821_H_/* * This file describes the memery mapping of the MC6821 PIA. * The unions describe overlayed registers. Which of them is used is * determined by bit 2 of the corresponding control register. * this files expects the PIA_REG_PADWIDTH to be defined the numeric * value of the register spacing. * * Data came from MFC-31-Developer Kit (from Ralph Seidel, * zodiac@darkness.gun.de) and Motorola Data Sheet (from  * Richard Hirst, srh@gpt.co.uk) * * 6.11.95 copyright Joerg Dorchain (dorchain@mpi-sb.mpg.de) * */#ifndef PIA_REG_PADWIDTH#define PIA_REG_PADWIDTH 255#endifstruct pia {	union {		volatile u_char pra;		volatile u_char ddra;	} ua;	u_char pad1[PIA_REG_PADWIDTH];	volatile u_char cra;	u_char pad2[PIA_REG_PADWIDTH];	union {		volatile u_char prb;		volatile u_char ddrb;	} ub;	u_char pad3[PIA_REG_PADWIDTH];	volatile u_char crb;	u_char pad4[PIA_REG_PADWIDTH];};#define ppra ua.pra#define pddra ua.ddra#define pprb ub.prb#define pddrb ub.ddrb#define PIA_C1_ENABLE_IRQ (1<<0)#define PIA_C1_LOW_TO_HIGH (1<<1)#define PIA_DDR (1<<2)#define PIA_IRQ2 (1<<6)#define PIA_IRQ1 (1<<7)#endif