xref: /freebsd/sys/dev/uart/uart_subr.c (revision a10cee30c94cf5944826d2a495e9cdf339dfbcc8)
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 	&uart_lpc_class,
56 };
57 static size_t uart_nclasses = sizeof(uart_classes) / sizeof(uart_classes[0]);
58 
59 static bus_addr_t
60 uart_parse_addr(const char **p)
61 {
62 	return (strtoul(*p, (char**)(uintptr_t)p, 0));
63 }
64 
65 static struct uart_class *
66 uart_parse_class(struct uart_class *class, const char **p)
67 {
68 	struct uart_class *uc;
69 	const char *nm;
70 	size_t len;
71 	u_int i;
72 
73 	for (i = 0; i < uart_nclasses; i++) {
74 		uc = uart_classes[i];
75 		nm = uart_getname(uc);
76 		if (nm == NULL || *nm == '\0')
77 			continue;
78 		len = strlen(nm);
79 		if (strncmp(nm, *p, len) == 0) {
80 			*p += len;
81 			return (uc);
82 		}
83 	}
84 	return (class);
85 }
86 
87 static long
88 uart_parse_long(const char **p)
89 {
90 	return (strtol(*p, (char**)(uintptr_t)p, 0));
91 }
92 
93 static int
94 uart_parse_parity(const char **p)
95 {
96 	if (!strncmp(*p, "even", 4)) {
97 		*p += 4;
98 		return UART_PARITY_EVEN;
99 	}
100 	if (!strncmp(*p, "mark", 4)) {
101 		*p += 4;
102 		return UART_PARITY_MARK;
103 	}
104 	if (!strncmp(*p, "none", 4)) {
105 		*p += 4;
106 		return UART_PARITY_NONE;
107 	}
108 	if (!strncmp(*p, "odd", 3)) {
109 		*p += 3;
110 		return UART_PARITY_ODD;
111 	}
112 	if (!strncmp(*p, "space", 5)) {
113 		*p += 5;
114 		return UART_PARITY_SPACE;
115 	}
116 	return (-1);
117 }
118 
119 static int
120 uart_parse_tag(const char **p)
121 {
122 	int tag;
123 
124 	if ((*p)[0] == 'b' && (*p)[1] == 'r') {
125 		tag = UART_TAG_BR;
126 		goto out;
127 	}
128 	if ((*p)[0] == 'c' && (*p)[1] == 'h') {
129 		tag = UART_TAG_CH;
130 		goto out;
131 	}
132 	if ((*p)[0] == 'd' && (*p)[1] == 'b') {
133 		tag = UART_TAG_DB;
134 		goto out;
135 	}
136 	if ((*p)[0] == 'd' && (*p)[1] == 't') {
137 		tag = UART_TAG_DT;
138 		goto out;
139 	}
140 	if ((*p)[0] == 'i' && (*p)[1] == 'o') {
141 		tag = UART_TAG_IO;
142 		goto out;
143 	}
144 	if ((*p)[0] == 'm' && (*p)[1] == 'm') {
145 		tag = UART_TAG_MM;
146 		goto out;
147 	}
148 	if ((*p)[0] == 'p' && (*p)[1] == 'a') {
149 		tag = UART_TAG_PA;
150 		goto out;
151 	}
152 	if ((*p)[0] == 'r' && (*p)[1] == 's') {
153 		tag = UART_TAG_RS;
154 		goto out;
155 	}
156 	if ((*p)[0] == 's' && (*p)[1] == 'b') {
157 		tag = UART_TAG_SB;
158 		goto out;
159 	}
160 	if ((*p)[0] == 'x' && (*p)[1] == 'o') {
161 		tag = UART_TAG_XO;
162 		goto out;
163 	}
164 	return (-1);
165 
166 out:
167 	*p += 2;
168 	if ((*p)[0] != ':')
169 		return (-1);
170 	(*p)++;
171 	return (tag);
172 }
173 
174 /*
175  * Parse a device specification. The specification is a list of attributes
176  * separated by commas. Each attribute is a tag-value pair with the tag and
177  * value separated by a colon. Supported tags are:
178  *
179  *	br = Baudrate
180  *	ch = Channel
181  *	db = Data bits
182  *	dt = Device type
183  *	io = I/O port address
184  *	mm = Memory mapped I/O address
185  *	pa = Parity
186  *	rs = Register shift
187  *	sb = Stopbits
188  *	xo = Device clock (xtal oscillator)
189  *
190  * The io and mm tags are mutually exclusive.
191  */
192 
193 int
194 uart_getenv(int devtype, struct uart_devinfo *di, struct uart_class *class)
195 {
196 	const char *spec;
197 	bus_addr_t addr = ~0U;
198 	int error;
199 
200 	/*
201 	 * All uart_class references are weak. Make sure the default
202 	 * device class has been compiled-in.
203 	 */
204 	if (class == NULL)
205 		return (ENXIO);
206 
207 	/*
208 	 * Check the environment variables "hw.uart.console" and
209 	 * "hw.uart.dbgport". These variables, when present, specify
210 	 * which UART port is to be used as serial console or debug
211 	 * port (resp).
212 	 */
213 	if (devtype == UART_DEV_CONSOLE)
214 		spec = getenv("hw.uart.console");
215 	else if (devtype == UART_DEV_DBGPORT)
216 		spec = getenv("hw.uart.dbgport");
217 	else
218 		spec = NULL;
219 	if (spec == NULL)
220 		return (ENXIO);
221 
222 	/* Set defaults. */
223 	di->bas.chan = 0;
224 	di->bas.regshft = 0;
225 	di->bas.rclk = 0;
226 	di->baudrate = 0;
227 	di->databits = 8;
228 	di->stopbits = 1;
229 	di->parity = UART_PARITY_NONE;
230 
231 	/* Parse the attributes. */
232 	while (1) {
233 		switch (uart_parse_tag(&spec)) {
234 		case UART_TAG_BR:
235 			di->baudrate = uart_parse_long(&spec);
236 			break;
237 		case UART_TAG_CH:
238 			di->bas.chan = uart_parse_long(&spec);
239 			break;
240 		case UART_TAG_DB:
241 			di->databits = uart_parse_long(&spec);
242 			break;
243 		case UART_TAG_DT:
244 			class = uart_parse_class(class, &spec);
245 			break;
246 		case UART_TAG_IO:
247 			di->bas.bst = uart_bus_space_io;
248 			addr = uart_parse_addr(&spec);
249 			break;
250 		case UART_TAG_MM:
251 			di->bas.bst = uart_bus_space_mem;
252 			addr = uart_parse_addr(&spec);
253 			break;
254 		case UART_TAG_PA:
255 			di->parity = uart_parse_parity(&spec);
256 			break;
257 		case UART_TAG_RS:
258 			di->bas.regshft = uart_parse_long(&spec);
259 			break;
260 		case UART_TAG_SB:
261 			di->stopbits = uart_parse_long(&spec);
262 			break;
263 		case UART_TAG_XO:
264 			di->bas.rclk = uart_parse_long(&spec);
265 			break;
266 		default:
267 			return (EINVAL);
268 		}
269 		if (*spec == '\0')
270 			break;
271 		if (*spec != ',')
272 			return (EINVAL);
273 		spec++;
274 	}
275 
276 	/*
277 	 * If we still have an invalid address, the specification must be
278 	 * missing an I/O port or memory address. We don't like that.
279 	 */
280 	if (addr == ~0U)
281 		return (EINVAL);
282 
283 	/*
284 	 * Accept only the well-known baudrates. Any invalid baudrate
285 	 * is silently replaced with a 0-valued baudrate. The 0 baudrate
286 	 * has special meaning. It means that we're not supposed to
287 	 * program the baudrate and simply communicate with whatever
288 	 * speed the hardware is currently programmed for.
289 	 */
290 	if (di->baudrate >= 19200) {
291 		if (di->baudrate % 19200)
292 			di->baudrate = 0;
293 	} else if (di->baudrate >= 1200) {
294 		if (di->baudrate % 1200)
295 			di->baudrate = 0;
296 	} else if (di->baudrate > 0) {
297 		if (di->baudrate % 75)
298 			di->baudrate = 0;
299 	} else
300 		di->baudrate = 0;
301 
302 	/* Set the ops and create a bus space handle. */
303 	di->ops = uart_getops(class);
304 	error = bus_space_map(di->bas.bst, addr, uart_getrange(class), 0,
305 	    &di->bas.bsh);
306 	return (error);
307 }
308