1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
|
/*
* Copyright (c) 2012 Sebastian Huber. All rights reserved.
*
* embedded brains GmbH
* Obere Lagerstr. 30
* 82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*/
#include <libchip/sersupp.h>
#include <bsp.h>
#include <bsp/io.h>
#include <bsp/rcc.h>
#include <bsp/irq.h>
#include <bsp/usart.h>
#include <bsp/stm32f4.h>
static volatile stm32f4_usart *usart_get_regs(const console_tbl *ct)
{
return (stm32f4_usart *) ct->ulCtrlPort1;
}
#if 0
static rtems_vector_number usart_get_irq_number(const console_tbl *ct)
{
return ct->ulIntVector;
}
#endif
static const stm32f4_rcc_index usart_rcc_index [] = {
STM32F4_RCC_USART1,
STM32F4_RCC_USART2,
STM32F4_RCC_USART3,
STM32F4_RCC_UART4,
STM32F4_RCC_UART5,
#ifdef STM32F4_FAMILY_F4XXXX
STM32F4_RCC_USART6
#endif /* STM32F4_FAMILY_F4XXXX */
};
static stm32f4_rcc_index usart_get_rcc_index(const console_tbl *ct)
{
return usart_rcc_index [ct->ulCtrlPort2];
}
static const uint8_t usart_pclk_index [] = { 1, 0, 0, 0, 0, 1 };
static const uint32_t usart_pclk_by_index [] = {
STM32F4_PCLK1,
STM32F4_PCLK2
};
static uint32_t usart_get_pclk(const console_tbl *ct)
{
return usart_pclk_by_index [usart_pclk_index [ct->ulCtrlPort2]];
}
static uint32_t usart_get_baud(const console_tbl *ct)
{
return ct->ulClock;
}
/*
* a = 8 * (2 - CR1[OVER8])
*
* usartdiv = div_mantissa + div_fraction / a
*
* baud = pclk / (a * usartdiv)
*
* usartdiv = pclk / (a * baud)
*
* Calculation in integer arithmetic:
*
* 1. div_mantissa = pclk / (a * baud)
*
* 2. div_fraction = pclk / (baud - a * div_mantissa)
*/
static uint32_t usart_get_bbr(
volatile stm32f4_usart *usart,
uint32_t pclk,
uint32_t baud
)
{
uint32_t a = 8 * (2 - ((usart->cr1 & STM32F4_USART_CR1_OVER8) != 0));
uint32_t div_mantissa_low = pclk / (a * baud);
uint32_t div_fraction_low = pclk / (baud - a * div_mantissa_low);
uint32_t div_mantissa_high;
uint32_t div_fraction_high;
uint32_t high_err;
uint32_t low_err;
uint32_t div_mantissa;
uint32_t div_fraction;
if (div_fraction_low < a - 1) {
div_mantissa_high = div_fraction_low;
div_fraction_high = div_fraction_low + 1;
} else {
div_mantissa_high = div_fraction_low + 1;
div_fraction_high = 0;
}
high_err = pclk - baud * (a * div_mantissa_high + div_fraction_high);
low_err = baud * (a * div_mantissa_low + div_fraction_low) - pclk;
if (low_err < high_err) {
div_mantissa = div_mantissa_low;
div_fraction = div_fraction_low;
} else {
div_mantissa = div_mantissa_high;
div_fraction = div_fraction_high;
}
return STM32F4_USART_BBR_DIV_MANTISSA(div_mantissa)
| STM32F4_USART_BBR_DIV_FRACTION(div_fraction);
}
static void usart_initialize(int minor)
{
const console_tbl *ct = Console_Port_Tbl [minor];
volatile stm32f4_usart *usart = usart_get_regs(ct);
uint32_t pclk = usart_get_pclk(ct);
uint32_t baud = usart_get_baud(ct);
stm32f4_rcc_index rcc_index = usart_get_rcc_index(ct);
stm32f4_rcc_set_clock(rcc_index, true);
usart->cr1 = 0;
usart->cr2 = 0;
usart->cr3 = 0;
usart->bbr = usart_get_bbr(usart, pclk, baud);
usart->cr1 = STM32F4_USART_CR1_UE
| STM32F4_USART_CR1_TE
| STM32F4_USART_CR1_RE;
}
static int usart_first_open(int major, int minor, void *arg)
{
rtems_libio_open_close_args_t *oc = (rtems_libio_open_close_args_t *) arg;
struct rtems_termios_tty *tty = (struct rtems_termios_tty *) oc->iop->data1;
const console_tbl *ct = Console_Port_Tbl [minor];
console_data *cd = &Console_Port_Data [minor];
cd->termios_data = tty;
rtems_termios_set_initial_baud(tty, ct->ulClock);
return 0;
}
static int usart_last_close(int major, int minor, void *arg)
{
return 0;
}
static int usart_read_polled(int minor)
{
const console_tbl *ct = Console_Port_Tbl [minor];
volatile stm32f4_usart *usart = usart_get_regs(ct);
if ((usart->sr & STM32F4_USART_SR_RXNE) != 0) {
return STM32F4_USART_DR_GET(usart->dr);
} else {
return -1;
}
}
static void usart_write_polled(int minor, char c)
{
const console_tbl *ct = Console_Port_Tbl [minor];
volatile stm32f4_usart *usart = usart_get_regs(ct);
while ((usart->sr & STM32F4_USART_SR_TXE) == 0) {
/* Wait */
}
usart->dr = STM32F4_USART_DR(c);
}
static ssize_t usart_write_support_polled(
int minor,
const char *s,
size_t n
)
{
ssize_t i = 0;
for (i = 0; i < n; ++i) {
usart_write_polled(minor, s [i]);
}
return n;
}
static int usart_set_attributes(int minor, const struct termios *term)
{
return -1;
}
const console_fns stm32f4_usart_fns = {
.deviceProbe = libchip_serial_default_probe,
.deviceFirstOpen = usart_first_open,
.deviceLastClose = usart_last_close,
.deviceRead = usart_read_polled,
.deviceWrite = usart_write_support_polled,
.deviceInitialize = usart_initialize,
.deviceWritePolled = usart_write_polled,
.deviceSetAttributes = usart_set_attributes,
.deviceOutputUsesInterrupts = false
};
|
