xref: /freebsd/sys/dev/uart/uart_subr.c (revision ea906c4152774dff300bb26fbfc1e4188351c89a)
1 /*-
2  * Copyright (c) 2004 Marcel Moolenaar
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  *    notice, this list of conditions and the following disclaimer.
11  * 2. Redistributions in binary form must reproduce the above copyright
12  *    notice, this list of conditions and the following disclaimer in the
13  *    documentation and/or other materials provided with the distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25  */
26 
27 #include <sys/cdefs.h>
28 __FBSDID("$FreeBSD$");
29 
30 #include <sys/param.h>
31 #include <sys/systm.h>
32 #include <sys/bus.h>
33 
34 #include <machine/bus.h>
35 #include <machine/vmparam.h>
36 
37 #include <dev/uart/uart.h>
38 #include <dev/uart/uart_cpu.h>
39 
40 #define	UART_TAG_BR	0
41 #define	UART_TAG_CH	1
42 #define	UART_TAG_DB	2
43 #define	UART_TAG_DT	3
44 #define	UART_TAG_IO	4
45 #define	UART_TAG_MM	5
46 #define	UART_TAG_PA	6
47 #define	UART_TAG_RS	7
48 #define	UART_TAG_SB	8
49 #define	UART_TAG_XO	9
50 
51 static struct uart_class *uart_classes[] = {
52 	&uart_ns8250_class,
53 	&uart_sab82532_class,
54 	&uart_z8530_class,
55 };
56 static size_t uart_nclasses = sizeof(uart_classes) / sizeof(uart_classes[0]);
57 
58 static bus_addr_t
59 uart_parse_addr(__const char **p)
60 {
61 	return (strtoul(*p, (char**)(uintptr_t)p, 0));
62 }
63 
64 static struct uart_class *
65 uart_parse_class(struct uart_class *class, __const char **p)
66 {
67 	struct uart_class *uc;
68 	const char *nm;
69 	size_t len;
70 	u_int i;
71 
72 	for (i = 0; i < uart_nclasses; i++) {
73 		uc = uart_classes[i];
74 		nm = uart_getname(uc);
75 		if (nm == NULL || *nm == '\0')
76 			continue;
77 		len = strlen(nm);
78 		if (strncmp(nm, *p, len) == 0) {
79 			*p += len;
80 			return (uc);
81 		}
82 	}
83 	return (class);
84 }
85 
86 static long
87 uart_parse_long(__const char **p)
88 {
89 	return (strtol(*p, (char**)(uintptr_t)p, 0));
90 }
91 
92 static int
93 uart_parse_parity(__const char **p)
94 {
95 	if (!strncmp(*p, "even", 4)) {
96 		*p += 4;
97 		return UART_PARITY_EVEN;
98 	}
99 	if (!strncmp(*p, "mark", 4)) {
100 		*p += 4;
101 		return UART_PARITY_MARK;
102 	}
103 	if (!strncmp(*p, "none", 4)) {
104 		*p += 4;
105 		return UART_PARITY_NONE;
106 	}
107 	if (!strncmp(*p, "odd", 3)) {
108 		*p += 3;
109 		return UART_PARITY_ODD;
110 	}
111 	if (!strncmp(*p, "space", 5)) {
112 		*p += 5;
113 		return UART_PARITY_SPACE;
114 	}
115 	return (-1);
116 }
117 
118 static int
119 uart_parse_tag(__const char **p)
120 {
121 	int tag;
122 
123 	if ((*p)[0] == 'b' && (*p)[1] == 'r') {
124 		tag = UART_TAG_BR;
125 		goto out;
126 	}
127 	if ((*p)[0] == 'c' && (*p)[1] == 'h') {
128 		tag = UART_TAG_CH;
129 		goto out;
130 	}
131 	if ((*p)[0] == 'd' && (*p)[1] == 'b') {
132 		tag = UART_TAG_DB;
133 		goto out;
134 	}
135 	if ((*p)[0] == 'd' && (*p)[1] == 't') {
136 		tag = UART_TAG_DT;
137 		goto out;
138 	}
139 	if ((*p)[0] == 'i' && (*p)[1] == 'o') {
140 		tag = UART_TAG_IO;
141 		goto out;
142 	}
143 	if ((*p)[0] == 'm' && (*p)[1] == 'm') {
144 		tag = UART_TAG_MM;
145 		goto out;
146 	}
147 	if ((*p)[0] == 'p' && (*p)[1] == 'a') {
148 		tag = UART_TAG_PA;
149 		goto out;
150 	}
151 	if ((*p)[0] == 'r' && (*p)[1] == 's') {
152 		tag = UART_TAG_RS;
153 		goto out;
154 	}
155 	if ((*p)[0] == 's' && (*p)[1] == 'b') {
156 		tag = UART_TAG_SB;
157 		goto out;
158 	}
159 	if ((*p)[0] == 'x' && (*p)[1] == 'o') {
160 		tag = UART_TAG_XO;
161 		goto out;
162 	}
163 	return (-1);
164 
165 out:
166 	*p += 2;
167 	if ((*p)[0] != ':')
168 		return (-1);
169 	(*p)++;
170 	return (tag);
171 }
172 
173 /*
174  * Parse a device specification. The specification is a list of attributes
175  * seperated by commas. Each attribute is a tag-value pair with the tag and
176  * value seperated by a colon. Supported tags are:
177  *
178  *	br = Baudrate
179  *	ch = Channel
180  *	db = Data bits
181  *	dt = Device type
182  *	io = I/O port address
183  *	mm = Memory mapped I/O address
184  *	pa = Parity
185  *	rs = Register shift
186  *	sb = Stopbits
187  *	xo = Device clock (xtal oscillator)
188  *
189  * The io and mm tags are mutually exclusive.
190  */
191 
192 int
193 uart_getenv(int devtype, struct uart_devinfo *di, struct uart_class *class)
194 {
195 	__const char *spec;
196 	bus_addr_t addr = ~0U;
197 	int error;
198 
199 	/*
200 	 * All uart_class references are weak. Make sure the default
201 	 * device class has been compiled-in.
202 	 */
203 	if (class == NULL)
204 		return (ENXIO);
205 
206 	/*
207 	 * Check the environment variables "hw.uart.console" and
208 	 * "hw.uart.dbgport". These variables, when present, specify
209 	 * which UART port is to be used as serial console or debug
210 	 * port (resp).
211 	 */
212 	if (devtype == UART_DEV_CONSOLE)
213 		spec = getenv("hw.uart.console");
214 	else if (devtype == UART_DEV_DBGPORT)
215 		spec = getenv("hw.uart.dbgport");
216 	else
217 		spec = NULL;
218 	if (spec == NULL)
219 		return (ENXIO);
220 
221 	/* Set defaults. */
222 	di->bas.chan = 0;
223 	di->bas.regshft = 0;
224 	di->bas.rclk = 0;
225 	di->baudrate = 0;
226 	di->databits = 8;
227 	di->stopbits = 1;
228 	di->parity = UART_PARITY_NONE;
229 
230 	/* Parse the attributes. */
231 	while (1) {
232 		switch (uart_parse_tag(&spec)) {
233 		case UART_TAG_BR:
234 			di->baudrate = uart_parse_long(&spec);
235 			break;
236 		case UART_TAG_CH:
237 			di->bas.chan = uart_parse_long(&spec);
238 			break;
239 		case UART_TAG_DB:
240 			di->databits = uart_parse_long(&spec);
241 			break;
242 		case UART_TAG_DT:
243 			class = uart_parse_class(class, &spec);
244 			break;
245 		case UART_TAG_IO:
246 			di->bas.bst = uart_bus_space_io;
247 			addr = uart_parse_addr(&spec);
248 			break;
249 		case UART_TAG_MM:
250 			di->bas.bst = uart_bus_space_mem;
251 			addr = uart_parse_addr(&spec);
252 			break;
253 		case UART_TAG_PA:
254 			di->parity = uart_parse_parity(&spec);
255 			break;
256 		case UART_TAG_RS:
257 			di->bas.regshft = uart_parse_long(&spec);
258 			break;
259 		case UART_TAG_SB:
260 			di->stopbits = uart_parse_long(&spec);
261 			break;
262 		case UART_TAG_XO:
263 			di->bas.rclk = uart_parse_long(&spec);
264 			break;
265 		default:
266 			return (EINVAL);
267 		}
268 		if (*spec == '\0')
269 			break;
270 		if (*spec != ',')
271 			return (EINVAL);
272 		spec++;
273 	}
274 
275 	/*
276 	 * If we still have an invalid address, the specification must be
277 	 * missing an I/O port or memory address. We don't like that.
278 	 */
279 	if (addr == ~0U)
280 		return (EINVAL);
281 
282 	/*
283 	 * Accept only the well-known baudrates. Any invalid baudrate
284 	 * is silently replaced with a 0-valued baudrate. The 0 baudrate
285 	 * has special meaning. It means that we're not supposed to
286 	 * program the baudrate and simply communicate with whatever
287 	 * speed the hardware is currently programmed for.
288 	 */
289 	if (di->baudrate >= 19200) {
290 		if (di->baudrate % 19200)
291 			di->baudrate = 0;
292 	} else if (di->baudrate >= 1200) {
293 		if (di->baudrate % 1200)
294 			di->baudrate = 0;
295 	} else if (di->baudrate > 0) {
296 		if (di->baudrate % 75)
297 			di->baudrate = 0;
298 	} else
299 		di->baudrate = 0;
300 
301 	/* Set the ops and create a bus space handle. */
302 	di->ops = uart_getops(class);
303 	error = bus_space_map(di->bas.bst, addr, uart_getrange(class), 0,
304 	    &di->bas.bsh);
305 	return (error);
306 }
307