xref: /freebsd/sys/dev/uart/uart_subr.c (revision cc16dea626cf2fc80cde667ac4798065108e596c)
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 #if defined(__arm__)
56 	&uart_lpc_class,
57 	&uart_s3c2410_class,
58 #endif
59 };
60 static size_t uart_nclasses = sizeof(uart_classes) / sizeof(uart_classes[0]);
61 
62 static bus_addr_t
63 uart_parse_addr(const char **p)
64 {
65 	return (strtoul(*p, (char**)(uintptr_t)p, 0));
66 }
67 
68 static struct uart_class *
69 uart_parse_class(struct uart_class *class, const char **p)
70 {
71 	struct uart_class *uc;
72 	const char *nm;
73 	size_t len;
74 	u_int i;
75 
76 	for (i = 0; i < uart_nclasses; i++) {
77 		uc = uart_classes[i];
78 		nm = uart_getname(uc);
79 		if (nm == NULL || *nm == '\0')
80 			continue;
81 		len = strlen(nm);
82 		if (strncmp(nm, *p, len) == 0) {
83 			*p += len;
84 			return (uc);
85 		}
86 	}
87 	return (class);
88 }
89 
90 static long
91 uart_parse_long(const char **p)
92 {
93 	return (strtol(*p, (char**)(uintptr_t)p, 0));
94 }
95 
96 static int
97 uart_parse_parity(const char **p)
98 {
99 	if (!strncmp(*p, "even", 4)) {
100 		*p += 4;
101 		return UART_PARITY_EVEN;
102 	}
103 	if (!strncmp(*p, "mark", 4)) {
104 		*p += 4;
105 		return UART_PARITY_MARK;
106 	}
107 	if (!strncmp(*p, "none", 4)) {
108 		*p += 4;
109 		return UART_PARITY_NONE;
110 	}
111 	if (!strncmp(*p, "odd", 3)) {
112 		*p += 3;
113 		return UART_PARITY_ODD;
114 	}
115 	if (!strncmp(*p, "space", 5)) {
116 		*p += 5;
117 		return UART_PARITY_SPACE;
118 	}
119 	return (-1);
120 }
121 
122 static int
123 uart_parse_tag(const char **p)
124 {
125 	int tag;
126 
127 	if ((*p)[0] == 'b' && (*p)[1] == 'r') {
128 		tag = UART_TAG_BR;
129 		goto out;
130 	}
131 	if ((*p)[0] == 'c' && (*p)[1] == 'h') {
132 		tag = UART_TAG_CH;
133 		goto out;
134 	}
135 	if ((*p)[0] == 'd' && (*p)[1] == 'b') {
136 		tag = UART_TAG_DB;
137 		goto out;
138 	}
139 	if ((*p)[0] == 'd' && (*p)[1] == 't') {
140 		tag = UART_TAG_DT;
141 		goto out;
142 	}
143 	if ((*p)[0] == 'i' && (*p)[1] == 'o') {
144 		tag = UART_TAG_IO;
145 		goto out;
146 	}
147 	if ((*p)[0] == 'm' && (*p)[1] == 'm') {
148 		tag = UART_TAG_MM;
149 		goto out;
150 	}
151 	if ((*p)[0] == 'p' && (*p)[1] == 'a') {
152 		tag = UART_TAG_PA;
153 		goto out;
154 	}
155 	if ((*p)[0] == 'r' && (*p)[1] == 's') {
156 		tag = UART_TAG_RS;
157 		goto out;
158 	}
159 	if ((*p)[0] == 's' && (*p)[1] == 'b') {
160 		tag = UART_TAG_SB;
161 		goto out;
162 	}
163 	if ((*p)[0] == 'x' && (*p)[1] == 'o') {
164 		tag = UART_TAG_XO;
165 		goto out;
166 	}
167 	return (-1);
168 
169 out:
170 	*p += 2;
171 	if ((*p)[0] != ':')
172 		return (-1);
173 	(*p)++;
174 	return (tag);
175 }
176 
177 /*
178  * Parse a device specification. The specification is a list of attributes
179  * separated by commas. Each attribute is a tag-value pair with the tag and
180  * value separated by a colon. Supported tags are:
181  *
182  *	br = Baudrate
183  *	ch = Channel
184  *	db = Data bits
185  *	dt = Device type
186  *	io = I/O port address
187  *	mm = Memory mapped I/O address
188  *	pa = Parity
189  *	rs = Register shift
190  *	sb = Stopbits
191  *	xo = Device clock (xtal oscillator)
192  *
193  * The io and mm tags are mutually exclusive.
194  */
195 
196 int
197 uart_getenv(int devtype, struct uart_devinfo *di, struct uart_class *class)
198 {
199 	const char *spec;
200 	bus_addr_t addr = ~0U;
201 	int error;
202 
203 	/*
204 	 * All uart_class references are weak. Make sure the default
205 	 * device class has been compiled-in.
206 	 */
207 	if (class == NULL)
208 		return (ENXIO);
209 
210 	/*
211 	 * Check the environment variables "hw.uart.console" and
212 	 * "hw.uart.dbgport". These variables, when present, specify
213 	 * which UART port is to be used as serial console or debug
214 	 * port (resp).
215 	 */
216 	if (devtype == UART_DEV_CONSOLE)
217 		spec = getenv("hw.uart.console");
218 	else if (devtype == UART_DEV_DBGPORT)
219 		spec = getenv("hw.uart.dbgport");
220 	else
221 		spec = NULL;
222 	if (spec == NULL)
223 		return (ENXIO);
224 
225 	/* Set defaults. */
226 	di->bas.chan = 0;
227 	di->bas.regshft = 0;
228 	di->bas.rclk = 0;
229 	di->baudrate = 0;
230 	di->databits = 8;
231 	di->stopbits = 1;
232 	di->parity = UART_PARITY_NONE;
233 
234 	/* Parse the attributes. */
235 	while (1) {
236 		switch (uart_parse_tag(&spec)) {
237 		case UART_TAG_BR:
238 			di->baudrate = uart_parse_long(&spec);
239 			break;
240 		case UART_TAG_CH:
241 			di->bas.chan = uart_parse_long(&spec);
242 			break;
243 		case UART_TAG_DB:
244 			di->databits = uart_parse_long(&spec);
245 			break;
246 		case UART_TAG_DT:
247 			class = uart_parse_class(class, &spec);
248 			break;
249 		case UART_TAG_IO:
250 			di->bas.bst = uart_bus_space_io;
251 			addr = uart_parse_addr(&spec);
252 			break;
253 		case UART_TAG_MM:
254 			di->bas.bst = uart_bus_space_mem;
255 			addr = uart_parse_addr(&spec);
256 			break;
257 		case UART_TAG_PA:
258 			di->parity = uart_parse_parity(&spec);
259 			break;
260 		case UART_TAG_RS:
261 			di->bas.regshft = uart_parse_long(&spec);
262 			break;
263 		case UART_TAG_SB:
264 			di->stopbits = uart_parse_long(&spec);
265 			break;
266 		case UART_TAG_XO:
267 			di->bas.rclk = uart_parse_long(&spec);
268 			break;
269 		default:
270 			return (EINVAL);
271 		}
272 		if (*spec == '\0')
273 			break;
274 		if (*spec != ',')
275 			return (EINVAL);
276 		spec++;
277 	}
278 
279 	/*
280 	 * If we still have an invalid address, the specification must be
281 	 * missing an I/O port or memory address. We don't like that.
282 	 */
283 	if (addr == ~0U)
284 		return (EINVAL);
285 
286 	/*
287 	 * Accept only the well-known baudrates. Any invalid baudrate
288 	 * is silently replaced with a 0-valued baudrate. The 0 baudrate
289 	 * has special meaning. It means that we're not supposed to
290 	 * program the baudrate and simply communicate with whatever
291 	 * speed the hardware is currently programmed for.
292 	 */
293 	if (di->baudrate >= 19200) {
294 		if (di->baudrate % 19200)
295 			di->baudrate = 0;
296 	} else if (di->baudrate >= 1200) {
297 		if (di->baudrate % 1200)
298 			di->baudrate = 0;
299 	} else if (di->baudrate > 0) {
300 		if (di->baudrate % 75)
301 			di->baudrate = 0;
302 	} else
303 		di->baudrate = 0;
304 
305 	/* Set the ops and create a bus space handle. */
306 	di->ops = uart_getops(class);
307 	error = bus_space_map(di->bas.bst, addr, uart_getrange(class), 0,
308 	    &di->bas.bsh);
309 	return (error);
310 }
311