1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright © 2006-2007 Intel Corporation 4 * 5 * Authors: 6 * Eric Anholt <eric@anholt.net> 7 */ 8 #include <linux/export.h> 9 #include <linux/i2c.h> 10 #include <linux/i2c-algo-bit.h> 11 12 #include "psb_drv.h" 13 #include "psb_intel_reg.h" 14 15 /* 16 * Intel GPIO access functions 17 */ 18 19 #define I2C_RISEFALL_TIME 20 20 21 static int get_clock(void *data) 22 { 23 struct psb_intel_i2c_chan *chan = data; 24 struct drm_device *dev = chan->drm_dev; 25 u32 val; 26 27 val = REG_READ(chan->reg); 28 return (val & GPIO_CLOCK_VAL_IN) != 0; 29 } 30 31 static int get_data(void *data) 32 { 33 struct psb_intel_i2c_chan *chan = data; 34 struct drm_device *dev = chan->drm_dev; 35 u32 val; 36 37 val = REG_READ(chan->reg); 38 return (val & GPIO_DATA_VAL_IN) != 0; 39 } 40 41 static void set_clock(void *data, int state_high) 42 { 43 struct psb_intel_i2c_chan *chan = data; 44 struct drm_device *dev = chan->drm_dev; 45 u32 reserved = 0, clock_bits; 46 47 /* On most chips, these bits must be preserved in software. */ 48 reserved = 49 REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE | 50 GPIO_CLOCK_PULLUP_DISABLE); 51 52 if (state_high) 53 clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK; 54 else 55 clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK | 56 GPIO_CLOCK_VAL_MASK; 57 REG_WRITE(chan->reg, reserved | clock_bits); 58 udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */ 59 } 60 61 static void set_data(void *data, int state_high) 62 { 63 struct psb_intel_i2c_chan *chan = data; 64 struct drm_device *dev = chan->drm_dev; 65 u32 reserved = 0, data_bits; 66 67 /* On most chips, these bits must be preserved in software. */ 68 reserved = 69 REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE | 70 GPIO_CLOCK_PULLUP_DISABLE); 71 72 if (state_high) 73 data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK; 74 else 75 data_bits = 76 GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK | 77 GPIO_DATA_VAL_MASK; 78 79 REG_WRITE(chan->reg, reserved | data_bits); 80 udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */ 81 } 82 83 /** 84 * psb_intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg 85 * @dev: DRM device 86 * @output: driver specific output device 87 * @reg: GPIO reg to use 88 * @name: name for this bus 89 * 90 * Creates and registers a new i2c bus with the Linux i2c layer, for use 91 * in output probing and control (e.g. DDC or SDVO control functions). 92 * 93 * Possible values for @reg include: 94 * %GPIOA 95 * %GPIOB 96 * %GPIOC 97 * %GPIOD 98 * %GPIOE 99 * %GPIOF 100 * %GPIOG 101 * %GPIOH 102 * see PRM for details on how these different busses are used. 103 */ 104 struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev, 105 const u32 reg, const char *name) 106 { 107 struct psb_intel_i2c_chan *chan; 108 109 chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL); 110 if (!chan) 111 goto out_free; 112 113 chan->drm_dev = dev; 114 chan->reg = reg; 115 snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name); 116 chan->adapter.owner = THIS_MODULE; 117 chan->adapter.algo_data = &chan->algo; 118 chan->adapter.dev.parent = &dev->pdev->dev; 119 chan->algo.setsda = set_data; 120 chan->algo.setscl = set_clock; 121 chan->algo.getsda = get_data; 122 chan->algo.getscl = get_clock; 123 chan->algo.udelay = 20; 124 chan->algo.timeout = usecs_to_jiffies(2200); 125 chan->algo.data = chan; 126 127 i2c_set_adapdata(&chan->adapter, chan); 128 129 if (i2c_bit_add_bus(&chan->adapter)) 130 goto out_free; 131 132 /* JJJ: raise SCL and SDA? */ 133 set_data(chan, 1); 134 set_clock(chan, 1); 135 udelay(20); 136 137 return chan; 138 139 out_free: 140 kfree(chan); 141 return NULL; 142 } 143 144 /** 145 * psb_intel_i2c_destroy - unregister and free i2c bus resources 146 * @output: channel to free 147 * 148 * Unregister the adapter from the i2c layer, then free the structure. 149 */ 150 void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan) 151 { 152 if (!chan) 153 return; 154 155 i2c_del_adapter(&chan->adapter); 156 kfree(chan); 157 } 158