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
53