linux/include/linux/mc6821.h
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   1#ifndef _MC6821_H_
   2#define _MC6821_H_
   3
   4/*
   5 * This file describes the memery mapping of the MC6821 PIA.
   6 * The unions describe overlayed registers. Which of them is used is
   7 * determined by bit 2 of the corresponding control register.
   8 * this files expects the PIA_REG_PADWIDTH to be defined the numeric
   9 * value of the register spacing.
  10 *
  11 * Data came from MFC-31-Developer Kit (from Ralph Seidel,
  12 * zodiac@darkness.gun.de) and Motorola Data Sheet (from 
  13 * Richard Hirst, srh@gpt.co.uk)
  14 *
  15 * 6.11.95 copyright Joerg Dorchain (dorchain@mpi-sb.mpg.de)
  16 *
  17 */
  18
  19#ifndef PIA_REG_PADWIDTH
  20#define PIA_REG_PADWIDTH 255
  21#endif
  22
  23struct pia {
  24        union {
  25                volatile u_char pra;
  26                volatile u_char ddra;
  27        } ua;
  28        u_char pad1[PIA_REG_PADWIDTH];
  29        volatile u_char cra;
  30        u_char pad2[PIA_REG_PADWIDTH];
  31        union {
  32                volatile u_char prb;
  33                volatile u_char ddrb;
  34        } ub;
  35        u_char pad3[PIA_REG_PADWIDTH];
  36        volatile u_char crb;
  37        u_char pad4[PIA_REG_PADWIDTH];
  38};
  39
  40#define ppra ua.pra
  41#define pddra ua.ddra
  42#define pprb ub.prb
  43#define pddrb ub.ddrb
  44
  45#define PIA_C1_ENABLE_IRQ (1<<0)
  46#define PIA_C1_LOW_TO_HIGH (1<<1)
  47#define PIA_DDR (1<<2)
  48#define PIA_IRQ2 (1<<6)
  49#define PIA_IRQ1 (1<<7)
  50
  51#endif
  52
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