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
14FILE_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 */
100void 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 */
119int 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 */
138int 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 */
148static 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 */
229static 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 */
247struct init_fn serial_init_fn __init_fn ( INIT_SERIAL ) = {
248	.initialise = serial_init,
249};
250
251/** Serial driver startup function */
252struct startup_fn serial_startup_fn __startup_fn ( STARTUP_EARLY ) = {
253	.shutdown = serial_fini,
254};
255