1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _MC6821_H_
3 #define _MC6821_H_
4
5 /*
6 * This file describes the memery mapping of the MC6821 PIA.
7 * The unions describe overlayed registers. Which of them is used is
8 * determined by bit 2 of the corresponding control register.
9 * this files expects the PIA_REG_PADWIDTH to be defined the numeric
10 * value of the register spacing.
11 *
12 * Data came from MFC-31-Developer Kit (from Ralph Seidel,
13 * zodiac@darkness.gun.de) and Motorola Data Sheet (from
14 * Richard Hirst, srh@gpt.co.uk)
15 *
16 * 6.11.95 copyright Joerg Dorchain (dorchain@mpi-sb.mpg.de)
17 *
18 */
19
20 #ifndef PIA_REG_PADWIDTH
21 #define PIA_REG_PADWIDTH 255
22 #endif
23
24 struct pia {
25 union {
26 volatile u_char pra;
27 volatile u_char ddra;
28 } ua;
29 u_char pad1[PIA_REG_PADWIDTH];
30 volatile u_char cra;
31 u_char pad2[PIA_REG_PADWIDTH];
32 union {
33 volatile u_char prb;
34 volatile u_char ddrb;
35 } ub;
36 u_char pad3[PIA_REG_PADWIDTH];
37 volatile u_char crb;
38 u_char pad4[PIA_REG_PADWIDTH];
39 };
40
41 #define ppra ua.pra
42 #define pddra ua.ddra
43 #define pprb ub.prb
44 #define pddrb ub.ddrb
45
46 #define PIA_C1_ENABLE_IRQ (1<<0)
47 #define PIA_C1_LOW_TO_HIGH (1<<1)
48 #define PIA_DDR (1<<2)
49 #define PIA_IRQ2 (1<<6)
50 #define PIA_IRQ1 (1<<7)
51
52 #endif