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Serenity Operating System
1/*
2 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 *
8 * 1. Redistributions of source code must retain the above copyright notice, this
9 * list of conditions and the following disclaimer.
10 *
11 * 2. Redistributions in binary form must reproduce the above copyright notice,
12 * this list of conditions and the following disclaimer in the documentation
13 * and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
16 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
18 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
22 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
23 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
24 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <Kernel/Devices/SerialDevice.h>
28#include <LibBareMetal/IO.h>
29
30namespace Kernel {
31
32SerialDevice::SerialDevice(int base_addr, unsigned minor)
33 : CharacterDevice(4, minor)
34 , m_base_addr(base_addr)
35{
36 initialize();
37}
38
39SerialDevice::~SerialDevice()
40{
41}
42
43bool SerialDevice::can_read(const FileDescription&) const
44{
45 return (get_line_status() & DataReady) != 0;
46}
47
48ssize_t SerialDevice::read(FileDescription&, u8* buffer, ssize_t size)
49{
50 if (!size)
51 return 0;
52
53 if (!(get_line_status() & DataReady))
54 return 0;
55
56 buffer[0] = IO::in8(m_base_addr);
57
58 return 1;
59}
60
61bool SerialDevice::can_write(const FileDescription&) const
62{
63 return (get_line_status() & EmptyTransmitterHoldingRegister) != 0;
64}
65
66ssize_t SerialDevice::write(FileDescription&, const u8* buffer, ssize_t size)
67{
68 if (!size)
69 return 0;
70
71 if (!(get_line_status() & EmptyTransmitterHoldingRegister))
72 return 0;
73
74 IO::out8(m_base_addr, buffer[0]);
75
76 return 1;
77}
78
79void SerialDevice::initialize()
80{
81 set_interrupts(0);
82 set_baud(Baud38400);
83 set_line_control(None, One, EightBits);
84 set_fifo_control(EnableFIFO | ClearReceiveFIFO | ClearTransmitFIFO | TriggerLevel4);
85 set_modem_control(RequestToSend | DataTerminalReady);
86}
87
88void SerialDevice::set_interrupts(char interrupt_enable)
89{
90 m_interrupt_enable = interrupt_enable;
91
92 IO::out8(m_base_addr + 1, interrupt_enable);
93}
94
95void SerialDevice::set_baud(Baud baud)
96{
97 m_baud = baud;
98
99 IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) | 0x80); // turn on DLAB
100 IO::out8(m_base_addr + 0, ((char)(baud)) >> 2); // lower half of divisor
101 IO::out8(m_base_addr + 1, ((char)(baud)) & 0xff); // upper half of divisor
102 IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & 0x7f); // turn off DLAB
103}
104
105void SerialDevice::set_fifo_control(char fifo_control)
106{
107 m_fifo_control = fifo_control;
108
109 IO::out8(m_base_addr + 2, fifo_control);
110}
111
112void SerialDevice::set_line_control(ParitySelect parity_select, StopBits stop_bits, WordLength word_length)
113{
114 m_parity_select = parity_select;
115 m_stop_bits = stop_bits;
116 m_word_length = word_length;
117
118 IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & (0xc0 | parity_select | stop_bits | word_length));
119}
120
121void SerialDevice::set_break_enable(bool break_enable)
122{
123 m_break_enable = break_enable;
124
125 IO::out8(m_base_addr + 3, IO::in8(m_base_addr + 3) & (break_enable ? 0xff : 0xbf));
126}
127
128void SerialDevice::set_modem_control(char modem_control)
129{
130 m_modem_control = modem_control;
131
132 IO::out8(m_base_addr + 4, modem_control);
133}
134
135char SerialDevice::get_line_status() const
136{
137 return IO::in8(m_base_addr + 5);
138}
139
140}