1 /*
2 * The serial port interface routines implement a simple polled i/o
3 * interface to a standard serial port. Due to the space restrictions
4 * for the boot blocks, no BIOS support is used (since BIOS requires
5 * expensive real/protected mode switches), instead the rudimentary
6 * BIOS support is duplicated here.
7 *
8 * The base address and speed for the i/o port are passed from the
9 * Makefile in the COMCONSOLE and CONSPEED preprocessor macros. The
10 * line control parameters are currently hard-coded to 8 bits, no
11 * parity, 1 stop bit (8N1). This can be changed in init_serial().
12 */
13
14 FILE_LICENCE ( GPL2_OR_LATER );
15
16 #include "stddef.h"
17 #include <gpxe/init.h>
18 #include <gpxe/io.h>
19 #include <unistd.h>
20 #include <gpxe/serial.h>
21 #include "config/serial.h"
22
23 /* Set default values if none specified */
24
25 #ifndef COMCONSOLE
26 #define COMCONSOLE 0x3f8
27 #endif
28
29 #ifndef COMSPEED
30 #define COMSPEED 9600
31 #endif
32
33 #ifndef COMDATA
34 #define COMDATA 8
35 #endif
36
37 #ifndef COMPARITY
38 #define COMPARITY 0
39 #endif
40
41 #ifndef COMSTOP
42 #define COMSTOP 1
43 #endif
44
45 #undef UART_BASE
46 #define UART_BASE ( COMCONSOLE )
47
48 #undef UART_BAUD
49 #define UART_BAUD ( COMSPEED )
50
51 #if ((115200%UART_BAUD) != 0)
52 #error Bad ttys0 baud rate
53 #endif
54
55 #define COMBRD (115200/UART_BAUD)
56
57 /* Line Control Settings */
58 #define UART_LCS ( ( ( (COMDATA) - 5 ) << 0 ) | \
59 ( ( (COMPARITY) ) << 3 ) | \
60 ( ( (COMSTOP) - 1 ) << 2 ) )
61
62 /* Data */
63 #define UART_RBR 0x00
64 #define UART_TBR 0x00
65
66 /* Control */
67 #define UART_IER 0x01
68 #define UART_IIR 0x02
69 #define UART_FCR 0x02
70 #define UART_LCR 0x03
71 #define UART_MCR 0x04
72 #define UART_DLL 0x00
73 #define UART_DLM 0x01
74
75 /* Status */
76 #define UART_LSR 0x05
77 #define UART_LSR_TEMPT 0x40 /* Transmitter empty */
78 #define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */
79 #define UART_LSR_BI 0x10 /* Break interrupt indicator */
80 #define UART_LSR_FE 0x08 /* Frame error indicator */
81 #define UART_LSR_PE 0x04 /* Parity error indicator */
82 #define UART_LSR_OE 0x02 /* Overrun error indicator */
83 #define UART_LSR_DR 0x01 /* Receiver data ready */
84
85 #define UART_MSR 0x06
86 #define UART_SCR 0x07
87
88 #if defined(UART_MEM)
89 #define uart_readb(addr) readb((addr))
90 #define uart_writeb(val,addr) writeb((val),(addr))
91 #else
92 #define uart_readb(addr) inb((addr))
93 #define uart_writeb(val,addr) outb((val),(addr))
94 #endif
95
96 /*
97 * void serial_putc(int ch);
98 * Write character `ch' to port UART_BASE.
99 */
serial_putc(int ch)100 void serial_putc ( int ch ) {
101 int i;
102 int status;
103 i = 1000; /* timeout */
104 while(--i > 0) {
105 status = uart_readb(UART_BASE + UART_LSR);
106 if (status & UART_LSR_THRE) {
107 /* TX buffer emtpy */
108 uart_writeb(ch, UART_BASE + UART_TBR);
109 break;
110 }
111 mdelay(2);
112 }
113 }
114
115 /*
116 * int serial_getc(void);
117 * Read a character from port UART_BASE.
118 */
serial_getc(void)119 int serial_getc ( void ) {
120 int status;
121 int ch;
122 do {
123 status = uart_readb(UART_BASE + UART_LSR);
124 } while((status & 1) == 0);
125 ch = uart_readb(UART_BASE + UART_RBR); /* fetch (first) character */
126 ch &= 0x7f; /* remove any parity bits we get */
127 if (ch == 0x7f) { /* Make DEL... look like BS */
128 ch = 0x08;
129 }
130 return ch;
131 }
132
133 /*
134 * int serial_ischar(void);
135 * If there is a character in the input buffer of port UART_BASE,
136 * return nonzero; otherwise return 0.
137 */
serial_ischar(void)138 int serial_ischar ( void ) {
139 int status;
140 status = uart_readb(UART_BASE + UART_LSR); /* line status reg; */
141 return status & 1; /* rx char available */
142 }
143
144 /*
145 * int serial_init(void);
146 * Initialize port UART_BASE to speed COMSPEED, line settings 8N1.
147 */
serial_init(void)148 static void serial_init ( void ) {
149 int status;
150 int divisor, lcs;
151
152 DBG ( "Serial port %#x initialising\n", UART_BASE );
153
154 divisor = COMBRD;
155 lcs = UART_LCS;
156
157
158 #ifdef COMPRESERVE
159 lcs = uart_readb(UART_BASE + UART_LCR) & 0x7f;
160 uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
161 divisor = (uart_readb(UART_BASE + UART_DLM) << 8) | uart_readb(UART_BASE + UART_DLL);
162 uart_writeb(lcs, UART_BASE + UART_LCR);
163 #endif
164
165 /* Set Baud Rate Divisor to COMSPEED, and test to see if the
166 * serial port appears to be present.
167 */
168 uart_writeb(0x80 | lcs, UART_BASE + UART_LCR);
169 uart_writeb(0xaa, UART_BASE + UART_DLL);
170 if (uart_readb(UART_BASE + UART_DLL) != 0xaa) {
171 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
172 goto out;
173 }
174 uart_writeb(0x55, UART_BASE + UART_DLL);
175 if (uart_readb(UART_BASE + UART_DLL) != 0x55) {
176 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
177 goto out;
178 }
179 uart_writeb(divisor & 0xff, UART_BASE + UART_DLL);
180 if (uart_readb(UART_BASE + UART_DLL) != (divisor & 0xff)) {
181 DBG ( "Serial port %#x UART_DLL failed\n", UART_BASE );
182 goto out;
183 }
184 uart_writeb(0xaa, UART_BASE + UART_DLM);
185 if (uart_readb(UART_BASE + UART_DLM) != 0xaa) {
186 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
187 goto out;
188 }
189 uart_writeb(0x55, UART_BASE + UART_DLM);
190 if (uart_readb(UART_BASE + UART_DLM) != 0x55) {
191 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
192 goto out;
193 }
194 uart_writeb((divisor >> 8) & 0xff, UART_BASE + UART_DLM);
195 if (uart_readb(UART_BASE + UART_DLM) != ((divisor >> 8) & 0xff)) {
196 DBG ( "Serial port %#x UART_DLM failed\n", UART_BASE );
197 goto out;
198 }
199 uart_writeb(lcs, UART_BASE + UART_LCR);
200
201 /* disable interrupts */
202 uart_writeb(0x0, UART_BASE + UART_IER);
203
204 /* disable fifo's */
205 uart_writeb(0x00, UART_BASE + UART_FCR);
206
207 /* Set clear to send, so flow control works... */
208 uart_writeb((1<<1), UART_BASE + UART_MCR);
209
210
211 /* Flush the input buffer. */
212 do {
213 /* rx buffer reg
214 * throw away (unconditionally the first time)
215 */
216 (void) uart_readb(UART_BASE + UART_RBR);
217 /* line status reg */
218 status = uart_readb(UART_BASE + UART_LSR);
219 } while(status & UART_LSR_DR);
220 out:
221 return;
222 }
223
224 /*
225 * void serial_fini(void);
226 * Cleanup our use of the serial port, in particular flush the
227 * output buffer so we don't accidentially lose characters.
228 */
serial_fini(int flags __unused)229 static void serial_fini ( int flags __unused ) {
230 int i, status;
231 /* Flush the output buffer to avoid dropping characters,
232 * if we are reinitializing the serial port.
233 */
234 i = 10000; /* timeout */
235 do {
236 status = uart_readb(UART_BASE + UART_LSR);
237 } while((--i > 0) && !(status & UART_LSR_TEMPT));
238 /* Don't mark it as disabled; it's still usable */
239 }
240
241 /**
242 * Serial driver initialisation function
243 *
244 * Initialise serial port early on so that it is available to capture
245 * early debug messages.
246 */
247 struct init_fn serial_init_fn __init_fn ( INIT_SERIAL ) = {
248 .initialise = serial_init,
249 };
250
251 /** Serial driver startup function */
252 struct startup_fn serial_startup_fn __startup_fn ( STARTUP_EARLY ) = {
253 .shutdown = serial_fini,
254 };
255