sys/dev/i2c/ddc.c

   1 /* $NetBSD: ddc.c,v 1.2 2007/10/19 11:59:43 ad 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 1.2 2007/10/19 11:59:43 ad 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
  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 1;
  74         return 0;
  75 }
  76
  77 static void
  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_address = ia->ia_addr;
  84
  85         aprint_naive(": DDC\n");
  86         aprint_normal(": DDC\n");
  87 }
  88
  89 /* XXX: add cdev ops? */
  90
  91 int
  92 ddc_read_edid(i2c_tag_t tag, uint8_t *dest, size_t len)
  93 {
  94         uint8_t         wbuf[2];
  95
  96         if (iic_acquire_bus(tag, I2C_F_POLL) != 0)
  97                 return -1;
  98
  99         wbuf[0] = DDC_EDID_START;       /* start address */
 100
 101         if (iic_exec(tag, I2C_OP_READ_WITH_STOP, DDC_ADDR, wbuf, 1, dest,
 102                 len, I2C_F_POLL)) {
 103                 iic_release_bus(tag, I2C_F_POLL);
 104                 return -1;
 105         }
 106         iic_release_bus(tag, I2C_F_POLL);
 107         return 0;
 108 }