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Guennadi Liakhovetski2fb28dc2008-08-31 00:39:47 +02001/*
2 * (C) Copyright 2002
3 * Gary Jennejohn, DENX Software Engineering, <gj@denx.de>
4 *
5 * (C) Copyright 2008
6 * Guennadi Liakhovetki, DENX Software Engineering, <lg@denx.de>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License as published by
10 * the Free Software Foundation; either version 2 of the License, or
11 * (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 *
22 */
23
24#include <common.h>
25
26#include <s3c6400.h>
27
28#ifdef CONFIG_SERIAL1
29#define UART_NR S3C64XX_UART0
30
31#elif defined(CONFIG_SERIAL2)
32#define UART_NR S3C64XX_UART1
33
34#elif defined(CONFIG_SERIAL3)
35#define UART_NR S3C64XX_UART2
36
37#else
38#error "Bad: you didn't configure serial ..."
39#endif
40
41#define barrier() asm volatile("" ::: "memory")
42
43/*
44 * The coefficient, used to calculate the baudrate on S3C6400 UARTs is
45 * calculated as
46 * C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT
47 * however, section 31.6.11 of the datasheet doesn't recomment using 1 for 1,
48 * 3 for 2, ... (2^n - 1) for n, instead, they suggest using these constants:
49 */
50static const int udivslot[] = {
51 0,
52 0x0080,
53 0x0808,
54 0x0888,
55 0x2222,
56 0x4924,
57 0x4a52,
58 0x54aa,
59 0x5555,
60 0xd555,
61 0xd5d5,
62 0xddd5,
63 0xdddd,
64 0xdfdd,
65 0xdfdf,
66 0xffdf,
67};
68
69void serial_setbrg(void)
70{
71 DECLARE_GLOBAL_DATA_PTR;
72 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
73 u32 pclk = get_PCLK();
74 u32 baudrate = gd->baudrate;
75 int i;
76
77 i = (pclk / baudrate) % 16;
78
79 uart->UBRDIV = pclk / baudrate / 16 - 1;
80 uart->UDIVSLOT = udivslot[i];
81
82 for (i = 0; i < 100; i++)
83 barrier();
84}
85
86/*
87 * Initialise the serial port with the given baudrate. The settings
88 * are always 8 data bits, no parity, 1 stop bit, no start bits.
89 */
90int serial_init(void)
91{
92 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
93
94 /* reset and enable FIFOs, set triggers to the maximum */
95 uart->UFCON = 0xff;
96 uart->UMCON = 0;
97 /* 8N1 */
98 uart->ULCON = 3;
99 /* No interrupts, no DMA, pure polling */
100 uart->UCON = 5;
101
102 serial_setbrg();
103
104 return 0;
105}
106
107/*
108 * Read a single byte from the serial port. Returns 1 on success, 0
109 * otherwise. When the function is succesfull, the character read is
110 * written into its argument c.
111 */
112int serial_getc(void)
113{
114 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
115
116 /* wait for character to arrive */
117 while (!(uart->UTRSTAT & 0x1));
118
119 return uart->URXH & 0xff;
120}
121
Guennadi Liakhovetski2fb28dc2008-08-31 00:39:47 +0200122#ifdef CONFIG_MODEM_SUPPORT
123static int be_quiet;
124void disable_putc(void)
125{
126 be_quiet = 1;
127}
128
129void enable_putc(void)
130{
131 be_quiet = 0;
132}
133#endif
134
135
136/*
137 * Output a single byte to the serial port.
138 */
139void serial_putc(const char c)
140{
141 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
142
143#ifdef CONFIG_MODEM_SUPPORT
144 if (be_quiet)
145 return;
146#endif
147
148 /* wait for room in the tx FIFO */
149 while (!(uart->UTRSTAT & 0x2));
150
Guennadi Liakhovetski2fb28dc2008-08-31 00:39:47 +0200151 uart->UTXH = c;
152
153 /* If \n, also do \r */
154 if (c == '\n')
155 serial_putc('\r');
156}
157
158/*
159 * Test whether a character is in the RX buffer
160 */
161int serial_tstc(void)
162{
163 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
164
165 return uart->UTRSTAT & 0x1;
166}
167
168void serial_puts(const char *s)
169{
170 while (*s)
171 serial_putc(*s++);
172}