1 /*
2 * (C) Copyright 2002
3 * Gary Jennejohn, DENX Software Engineering, <garyj@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 */
24 #include <common.h>
25 #include <linux/compiler.h>
26 #include <serial.h>
27 #include <asm/arch/s3c6400.h>
29 DECLARE_GLOBAL_DATA_PTR;
31 #ifdef CONFIG_SERIAL1
32 #define UART_NR S3C64XX_UART0
34 #elif defined(CONFIG_SERIAL2)
35 #define UART_NR S3C64XX_UART1
37 #elif defined(CONFIG_SERIAL3)
38 #define UART_NR S3C64XX_UART2
40 #else
41 #error "Bad: you didn't configure serial ..."
42 #endif
44 /*
45 * The coefficient, used to calculate the baudrate on S3C6400 UARTs is
46 * calculated as
47 * C = UBRDIV * 16 + number_of_set_bits_in_UDIVSLOT
48 * however, section 31.6.11 of the datasheet doesn't recomment using 1 for 1,
49 * 3 for 2, ... (2^n - 1) for n, instead, they suggest using these constants:
50 */
51 static const int udivslot[] = {
52 0,
53 0x0080,
54 0x0808,
55 0x0888,
56 0x2222,
57 0x4924,
58 0x4a52,
59 0x54aa,
60 0x5555,
61 0xd555,
62 0xd5d5,
63 0xddd5,
64 0xdddd,
65 0xdfdd,
66 0xdfdf,
67 0xffdf,
68 };
70 static void s3c64xx_serial_setbrg(void)
71 {
72 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
73 u32 pclk = get_PCLK();
74 u32 baudrate = gd->baudrate;
75 int i;
77 i = (pclk / baudrate) % 16;
79 uart->UBRDIV = pclk / baudrate / 16 - 1;
80 uart->UDIVSLOT = udivslot[i];
82 for (i = 0; i < 100; i++)
83 barrier();
84 }
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 */
90 static int s3c64xx_serial_init(void)
91 {
92 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
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;
102 serial_setbrg();
104 return 0;
105 }
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 */
112 static int s3c64xx_serial_getc(void)
113 {
114 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
116 /* wait for character to arrive */
117 while (!(uart->UTRSTAT & 0x1));
119 return uart->URXH & 0xff;
120 }
122 #ifdef CONFIG_MODEM_SUPPORT
123 static int be_quiet;
124 void disable_putc(void)
125 {
126 be_quiet = 1;
127 }
129 void enable_putc(void)
130 {
131 be_quiet = 0;
132 }
133 #endif
136 /*
137 * Output a single byte to the serial port.
138 */
139 static void s3c64xx_serial_putc(const char c)
140 {
141 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
143 #ifdef CONFIG_MODEM_SUPPORT
144 if (be_quiet)
145 return;
146 #endif
148 /* wait for room in the tx FIFO */
149 while (!(uart->UTRSTAT & 0x2));
151 uart->UTXH = c;
153 /* If \n, also do \r */
154 if (c == '\n')
155 serial_putc('\r');
156 }
158 /*
159 * Test whether a character is in the RX buffer
160 */
161 static int s3c64xx_serial_tstc(void)
162 {
163 s3c64xx_uart *const uart = s3c64xx_get_base_uart(UART_NR);
165 return uart->UTRSTAT & 0x1;
166 }
168 static struct serial_device s3c64xx_serial_drv = {
169 .name = "s3c64xx_serial",
170 .start = s3c64xx_serial_init,
171 .stop = NULL,
172 .setbrg = s3c64xx_serial_setbrg,
173 .putc = s3c64xx_serial_putc,
174 .puts = default_serial_puts,
175 .getc = s3c64xx_serial_getc,
176 .tstc = s3c64xx_serial_tstc,
177 };
179 void s3c64xx_serial_initialize(void)
180 {
181 serial_register(&s3c64xx_serial_drv);
182 }
184 __weak struct serial_device *default_serial_console(void)
185 {
186 return &s3c64xx_serial_drv;
187 }