xref: /qemu/include/hw/char/avr_usart.h (revision a1a62ced)
1 /*
2  * AVR USART
3  *
4  * Copyright (c) 2018 University of Kent
5  * Author: Sarah Harris
6  *
7  * This library is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * This library is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with this library; if not, see
19  * <http://www.gnu.org/licenses/lgpl-2.1.html>
20  */
21 
22 #ifndef HW_CHAR_AVR_USART_H
23 #define HW_CHAR_AVR_USART_H
24 
25 #include "hw/sysbus.h"
26 #include "chardev/char-fe.h"
27 #include "qom/object.h"
28 
29 /* Offsets of registers. */
30 #define USART_DR   0x06
31 #define USART_CSRA  0x00
32 #define USART_CSRB  0x01
33 #define USART_CSRC  0x02
34 #define USART_BRRH 0x05
35 #define USART_BRRL 0x04
36 
37 /* Relevant bits in registers. */
38 #define USART_CSRA_RXC    (1 << 7)
39 #define USART_CSRA_TXC    (1 << 6)
40 #define USART_CSRA_DRE    (1 << 5)
41 #define USART_CSRA_MPCM   (1 << 0)
42 
43 #define USART_CSRB_RXCIE  (1 << 7)
44 #define USART_CSRB_TXCIE  (1 << 6)
45 #define USART_CSRB_DREIE  (1 << 5)
46 #define USART_CSRB_RXEN   (1 << 4)
47 #define USART_CSRB_TXEN   (1 << 3)
48 #define USART_CSRB_CSZ2   (1 << 2)
49 #define USART_CSRB_RXB8   (1 << 1)
50 #define USART_CSRB_TXB8   (1 << 0)
51 
52 #define USART_CSRC_MSEL1  (1 << 7)
53 #define USART_CSRC_MSEL0  (1 << 6)
54 #define USART_CSRC_PM1    (1 << 5)
55 #define USART_CSRC_PM0    (1 << 4)
56 #define USART_CSRC_CSZ1   (1 << 2)
57 #define USART_CSRC_CSZ0   (1 << 1)
58 
59 #define TYPE_AVR_USART "avr-usart"
60 OBJECT_DECLARE_SIMPLE_TYPE(AVRUsartState, AVR_USART)
61 
62 struct AVRUsartState {
63     /* <private> */
64     SysBusDevice parent_obj;
65 
66     /* <public> */
67     MemoryRegion mmio;
68 
69     CharBackend chr;
70 
71     bool enabled;
72 
73     uint8_t data;
74     bool data_valid;
75     uint8_t char_mask;
76     /* Control and Status Registers */
77     uint8_t csra;
78     uint8_t csrb;
79     uint8_t csrc;
80     /* Baud Rate Registers (low/high byte) */
81     uint8_t brrh;
82     uint8_t brrl;
83 
84     /* Receive Complete */
85     qemu_irq rxc_irq;
86     /* Transmit Complete */
87     qemu_irq txc_irq;
88     /* Data Register Empty */
89     qemu_irq dre_irq;
90 };
91 
92 #endif /* HW_CHAR_AVR_USART_H */
93