1 /* $NetBSD: ddc.c,v 1.9 2019/12/23 18:12:50 thorpej Exp $ */
2
3 /*-
4 * Copyright (c) 2006 Itronix Inc.
5 * All rights reserved.
6 *
7 * Written by Garrett D'Amore for Itronix Inc.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. The name of Itronix Inc. may not be used to endorse
18 * or promote products derived from this software without specific
19 * prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY ITRONIX INC. ``AS IS'' AND ANY EXPRESS
22 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
23 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL ITRONIX INC. BE LIABLE FOR ANY
25 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
27 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
29 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
30 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
31 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 __KERNEL_RCSID(0, "$NetBSD: ddc.c,v 1.9 2019/12/23 18:12:50 thorpej Exp $");
36
37 #include <sys/param.h>
38 #include <sys/systm.h>
39 #include <sys/device.h>
40 #include <sys/kernel.h>
41
42 #include <sys/bus.h>
43 #include <dev/i2c/i2cvar.h>
44 #include <dev/i2c/ddcreg.h>
45 #include <dev/i2c/ddcvar.h>
46
47 /*
48 * VESA Display Data Channel I2C client, used to access EDID
49 * information.
50 *
51 * Note that this only supports DDC version 2, which uses normal I2C.
52 * The older DDCv1 standard used sync signaling to provide the I2C
53 * clock, and is typically not used on reasonably recent monitors.
54 */
55
56 struct ddc_softc {
57 i2c_tag_t sc_tag;
58 int sc_address;
59 };
60
61 static int ddc_match(device_t, cfdata_t, void *);
62 static void ddc_attach(device_t, device_t, void *);
63
64 CFATTACH_DECL_NEW(ddc, sizeof (struct ddc_softc),
65 ddc_match, ddc_attach, NULL, NULL);
66
67 static int
ddc_match(device_t parent,cfdata_t cf,void * aux)68 ddc_match(device_t parent, cfdata_t cf, void *aux)
69 {
70 struct i2c_attach_args *ia = aux;
71
72 if (ia->ia_addr == DDC_ADDR)
73 return I2C_MATCH_ADDRESS_ONLY;
74 return 0;
75 }
76
77 static void
ddc_attach(device_t parent,device_t self,void * aux)78 ddc_attach(device_t parent, device_t self, void *aux)
79 {
80 struct ddc_softc *sc = device_private(self);
81 struct i2c_attach_args *ia = aux;
82
83 sc->sc_tag = ia->ia_tag;
84 sc->sc_address = ia->ia_addr;
85
86 aprint_naive(": DDC\n");
87 aprint_normal(": DDC\n");
88 }
89
90 /* XXX: add cdev ops? */
91
92 int
ddc_read_edid(i2c_tag_t tag,uint8_t * dest,size_t len)93 ddc_read_edid(i2c_tag_t tag, uint8_t *dest, size_t len)
94 {
95 return ddc_read_edid_block(tag, dest, len, DDC_EDID_START);
96 }
97
98 int
ddc_read_edid_block(i2c_tag_t tag,uint8_t * dest,size_t len,uint8_t block)99 ddc_read_edid_block(i2c_tag_t tag, uint8_t *dest, size_t len, uint8_t block)
100 {
101 uint8_t edid[256];
102 uint8_t wbuf[2];
103 int error;
104
105 if ((error = iic_acquire_bus(tag, 0)) != 0)
106 return error;
107
108 wbuf[0] = block >> 1; /* start address */
109
110 if ((error = iic_exec(tag, I2C_OP_READ_WITH_STOP, DDC_ADDR, wbuf, 1,
111 edid, sizeof(edid), 0)) != 0) {
112 iic_release_bus(tag, 0);
113 return error;
114 }
115 iic_release_bus(tag, 0);
116
117 if (block & 1) {
118 memcpy(dest, &edid[128], uimin(len, 128));
119 } else {
120 memcpy(dest, &edid[0], uimin(len, 128));
121 }
122
123 return 0;
124 }
125
126 int
ddc_dev_read_edid(device_t dev,uint8_t * dest,size_t len)127 ddc_dev_read_edid(device_t dev, uint8_t *dest, size_t len)
128 {
129 return ddc_dev_read_edid_block(dev, dest, len, DDC_EDID_START);
130 }
131
132 int
ddc_dev_read_edid_block(device_t dev,uint8_t * dest,size_t len,uint8_t block)133 ddc_dev_read_edid_block(device_t dev, uint8_t *dest, size_t len, uint8_t block)
134 {
135 if (!device_is_a(dev, "ddc"))
136 return EINVAL;
137
138 const struct ddc_softc *sc = device_private(dev);
139 return ddc_read_edid_block(sc->sc_tag, dest, len, block);
140 }
141