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 9 #include <linux/delay.h> 10 #include <linux/export.h> 11 #include <linux/i2c-algo-bit.h> 12 #include <linux/i2c.h> 13 14 #include "psb_drv.h" 15 #include "psb_intel_reg.h" 16 17 /* 18 * Intel GPIO access functions 19 */ 20 21 #define I2C_RISEFALL_TIME 20 22 23 static int get_clock(void *data) 24 { 25 struct gma_i2c_chan *chan = data; 26 struct drm_device *dev = chan->drm_dev; 27 u32 val; 28 29 val = REG_READ(chan->reg); 30 return (val & GPIO_CLOCK_VAL_IN) != 0; 31 } 32 33 static int get_data(void *data) 34 { 35 struct gma_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_DATA_VAL_IN) != 0; 41 } 42 43 static void set_clock(void *data, int state_high) 44 { 45 struct gma_i2c_chan *chan = data; 46 struct drm_device *dev = chan->drm_dev; 47 u32 reserved = 0, clock_bits; 48 49 /* On most chips, these bits must be preserved in software. */ 50 reserved = 51 REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE | 52 GPIO_CLOCK_PULLUP_DISABLE); 53 54 if (state_high) 55 clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK; 56 else 57 clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK | 58 GPIO_CLOCK_VAL_MASK; 59 REG_WRITE(chan->reg, reserved | clock_bits); 60 udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */ 61 } 62 63 static void set_data(void *data, int state_high) 64 { 65 struct gma_i2c_chan *chan = data; 66 struct drm_device *dev = chan->drm_dev; 67 u32 reserved = 0, data_bits; 68 69 /* On most chips, these bits must be preserved in software. */ 70 reserved = 71 REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE | 72 GPIO_CLOCK_PULLUP_DISABLE); 73 74 if (state_high) 75 data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK; 76 else 77 data_bits = 78 GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK | 79 GPIO_DATA_VAL_MASK; 80 81 REG_WRITE(chan->reg, reserved | data_bits); 82 udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */ 83 } 84 85 /** 86 * gma_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg 87 * @dev: DRM device 88 * @reg: GPIO reg to use 89 * @name: name for this bus 90 * 91 * Creates and registers a new i2c bus with the Linux i2c layer, for use 92 * in output probing and control (e.g. DDC or SDVO control functions). 93 * 94 * Possible values for @reg include: 95 * %GPIOA 96 * %GPIOB 97 * %GPIOC 98 * %GPIOD 99 * %GPIOE 100 * %GPIOF 101 * %GPIOG 102 * %GPIOH 103 * see PRM for details on how these different busses are used. 104 */ 105 struct gma_i2c_chan *gma_i2c_create(struct drm_device *dev, const u32 reg, 106 const char *name) 107 { 108 struct gma_i2c_chan *chan; 109 110 chan = kzalloc(sizeof(struct gma_i2c_chan), GFP_KERNEL); 111 if (!chan) 112 goto out_free; 113 114 chan->drm_dev = dev; 115 chan->reg = reg; 116 snprintf(chan->base.name, I2C_NAME_SIZE, "intel drm %s", name); 117 chan->base.owner = THIS_MODULE; 118 chan->base.algo_data = &chan->algo; 119 chan->base.dev.parent = dev->dev; 120 chan->algo.setsda = set_data; 121 chan->algo.setscl = set_clock; 122 chan->algo.getsda = get_data; 123 chan->algo.getscl = get_clock; 124 chan->algo.udelay = 20; 125 chan->algo.timeout = usecs_to_jiffies(2200); 126 chan->algo.data = chan; 127 128 i2c_set_adapdata(&chan->base, chan); 129 130 if (i2c_bit_add_bus(&chan->base)) 131 goto out_free; 132 133 /* JJJ: raise SCL and SDA? */ 134 set_data(chan, 1); 135 set_clock(chan, 1); 136 udelay(20); 137 138 return chan; 139 140 out_free: 141 kfree(chan); 142 return NULL; 143 } 144 145 /** 146 * gma_i2c_destroy - unregister and free i2c bus resources 147 * @chan: channel to free 148 * 149 * Unregister the adapter from the i2c layer, then free the structure. 150 */ 151 void gma_i2c_destroy(struct gma_i2c_chan *chan) 152 { 153 if (!chan) 154 return; 155 156 i2c_del_adapter(&chan->base); 157 kfree(chan); 158 } 159