1 /* 2 * Copyright © 2006-2007 Intel Corporation 3 * 4 * This program is free software; you can redistribute it and/or modify it 5 * under the terms and conditions of the GNU General Public License, 6 * version 2, as published by the Free Software Foundation. 7 * 8 * This program is distributed in the hope it will be useful, but WITHOUT 9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 11 * more details. 12 * 13 * You should have received a copy of the GNU General Public License along with 14 * this program; if not, write to the Free Software Foundation, Inc., 15 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. 16 * 17 * Authors: 18 * Eric Anholt <eric@anholt.net> 19 */ 20 #include <linux/export.h> 21 #include <linux/i2c.h> 22 #include <linux/i2c-algo-bit.h> 23 24 #include "psb_drv.h" 25 #include "psb_intel_reg.h" 26 27 /* 28 * Intel GPIO access functions 29 */ 30 31 #define I2C_RISEFALL_TIME 20 32 33 static int get_clock(void *data) 34 { 35 struct psb_intel_i2c_chan *chan = data; 36 struct drm_device *dev = chan->drm_dev; 37 u32 val; 38 39 val = REG_READ(chan->reg); 40 return (val & GPIO_CLOCK_VAL_IN) != 0; 41 } 42 43 static int get_data(void *data) 44 { 45 struct psb_intel_i2c_chan *chan = data; 46 struct drm_device *dev = chan->drm_dev; 47 u32 val; 48 49 val = REG_READ(chan->reg); 50 return (val & GPIO_DATA_VAL_IN) != 0; 51 } 52 53 static void set_clock(void *data, int state_high) 54 { 55 struct psb_intel_i2c_chan *chan = data; 56 struct drm_device *dev = chan->drm_dev; 57 u32 reserved = 0, clock_bits; 58 59 /* On most chips, these bits must be preserved in software. */ 60 reserved = 61 REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE | 62 GPIO_CLOCK_PULLUP_DISABLE); 63 64 if (state_high) 65 clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK; 66 else 67 clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK | 68 GPIO_CLOCK_VAL_MASK; 69 REG_WRITE(chan->reg, reserved | clock_bits); 70 udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */ 71 } 72 73 static void set_data(void *data, int state_high) 74 { 75 struct psb_intel_i2c_chan *chan = data; 76 struct drm_device *dev = chan->drm_dev; 77 u32 reserved = 0, data_bits; 78 79 /* On most chips, these bits must be preserved in software. */ 80 reserved = 81 REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE | 82 GPIO_CLOCK_PULLUP_DISABLE); 83 84 if (state_high) 85 data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK; 86 else 87 data_bits = 88 GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK | 89 GPIO_DATA_VAL_MASK; 90 91 REG_WRITE(chan->reg, reserved | data_bits); 92 udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */ 93 } 94 95 /** 96 * psb_intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg 97 * @dev: DRM device 98 * @output: driver specific output device 99 * @reg: GPIO reg to use 100 * @name: name for this bus 101 * 102 * Creates and registers a new i2c bus with the Linux i2c layer, for use 103 * in output probing and control (e.g. DDC or SDVO control functions). 104 * 105 * Possible values for @reg include: 106 * %GPIOA 107 * %GPIOB 108 * %GPIOC 109 * %GPIOD 110 * %GPIOE 111 * %GPIOF 112 * %GPIOG 113 * %GPIOH 114 * see PRM for details on how these different busses are used. 115 */ 116 struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev, 117 const u32 reg, const char *name) 118 { 119 struct psb_intel_i2c_chan *chan; 120 121 chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL); 122 if (!chan) 123 goto out_free; 124 125 chan->drm_dev = dev; 126 chan->reg = reg; 127 snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name); 128 chan->adapter.owner = THIS_MODULE; 129 chan->adapter.algo_data = &chan->algo; 130 chan->adapter.dev.parent = &dev->pdev->dev; 131 chan->algo.setsda = set_data; 132 chan->algo.setscl = set_clock; 133 chan->algo.getsda = get_data; 134 chan->algo.getscl = get_clock; 135 chan->algo.udelay = 20; 136 chan->algo.timeout = usecs_to_jiffies(2200); 137 chan->algo.data = chan; 138 139 i2c_set_adapdata(&chan->adapter, chan); 140 141 if (i2c_bit_add_bus(&chan->adapter)) 142 goto out_free; 143 144 /* JJJ: raise SCL and SDA? */ 145 set_data(chan, 1); 146 set_clock(chan, 1); 147 udelay(20); 148 149 return chan; 150 151 out_free: 152 kfree(chan); 153 return NULL; 154 } 155 156 /** 157 * psb_intel_i2c_destroy - unregister and free i2c bus resources 158 * @output: channel to free 159 * 160 * Unregister the adapter from the i2c layer, then free the structure. 161 */ 162 void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan) 163 { 164 if (!chan) 165 return; 166 167 i2c_del_adapter(&chan->adapter); 168 kfree(chan); 169 } 170