1 /* $NetBSD: ddc.c,v 1.3 2008/05/04 15:26:29 xtraeme 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 1.3 2008/05/04 15:26:29 xtraeme 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 } 109