drivers/gpu/drm/i915/intel_i2c.c

   1 /*
   2  * Copyright (c) 2006 Dave Airlie <airlied@linux.ie>
   3  * Copyright © 2006-2008 Intel Corporation
   4  *   Jesse Barnes <jesse.barnes@intel.com>
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice (including the next
  14  * paragraph) shall be included in all copies or substantial portions of the
  15  * Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  22  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  23  * DEALINGS IN THE SOFTWARE.
  24  *
  25  * Authors:
  26  *      Eric Anholt <eric@anholt.net>
  27  */
  28 #include <linux/i2c.h>
  29 #include <linux/i2c-id.h>
  30 #include <linux/i2c-algo-bit.h>
  31 #include "drmP.h"
  32 #include "drm.h"
  33 #include "intel_drv.h"
  34 #include "i915_drm.h"
  35 #include "i915_drv.h"
  36
  37 /*
  38  * Intel GPIO access functions
  39  */
  40
  41 #define I2C_RISEFALL_TIME 20
  42
  43 static int get_clock(void *data)
  44 {
  45         struct intel_i2c_chan *chan = data;
  46         struct drm_i915_private *dev_priv = chan->drm_dev->dev_private;
  47         u32 val;
  48
  49         val = I915_READ(chan->reg);
  50         return ((val & GPIO_CLOCK_VAL_IN) != 0);
  51 }
  52
  53 static int get_data(void *data)
  54 {
  55         struct intel_i2c_chan *chan = data;
  56         struct drm_i915_private *dev_priv = chan->drm_dev->dev_private;
  57         u32 val;
  58
  59         val = I915_READ(chan->reg);
  60         return ((val & GPIO_DATA_VAL_IN) != 0);
  61 }
  62
  63 static void set_clock(void *data, int state_high)
  64 {
  65         struct intel_i2c_chan *chan = data;
  66         struct drm_device *dev = chan->drm_dev;
  67         struct drm_i915_private *dev_priv = chan->drm_dev->dev_private;
  68         u32 reserved = 0, clock_bits;
  69
  70         /* On most chips, these bits must be preserved in software. */
  71         if (!IS_I830(dev) && !IS_845G(dev))
  72                 reserved = I915_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
  73                                                    GPIO_CLOCK_PULLUP_DISABLE);
  74
  75         if (state_high)
  76                 clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK;
  77         else
  78                 clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK |
  79                         GPIO_CLOCK_VAL_MASK;
  80         I915_WRITE(chan->reg, reserved | clock_bits);
  81         udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */
  82 }
  83
  84 static void set_data(void *data, int state_high)
  85 {
  86         struct intel_i2c_chan *chan = data;
  87         struct drm_device *dev = chan->drm_dev;
  88         struct drm_i915_private *dev_priv = chan->drm_dev->dev_private;
  89         u32 reserved = 0, data_bits;
  90
  91         /* On most chips, these bits must be preserved in software. */
  92         if (!IS_I830(dev) && !IS_845G(dev))
  93                 reserved = I915_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
  94                                                    GPIO_CLOCK_PULLUP_DISABLE);
  95
  96         if (state_high)
  97                 data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK;
  98         else
  99                 data_bits = GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK |
 100                         GPIO_DATA_VAL_MASK;
 101
 102         I915_WRITE(chan->reg, reserved | data_bits);
 103         udelay(I2C_RISEFALL_TIME); /* wait for the line to change state */
 104 }
 105
 106 /**
 107  * intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
 108  * @dev: DRM device
 109  * @output: driver specific output device
 110  * @reg: GPIO reg to use
 111  * @name: name for this bus
 112  *
 113  * Creates and registers a new i2c bus with the Linux i2c layer, for use
 114  * in output probing and control (e.g. DDC or SDVO control functions).
 115  *
 116  * Possible values for @reg include:
 117  *   %GPIOA
 118  *   %GPIOB
 119  *   %GPIOC
 120  *   %GPIOD
 121  *   %GPIOE
 122  *   %GPIOF
 123  *   %GPIOG
 124  *   %GPIOH
 125  * see PRM for details on how these different busses are used.
 126  */
 127 struct intel_i2c_chan *intel_i2c_create(struct drm_device *dev, const u32 reg,
 128                                         const char *name)
 129 {
 130         struct intel_i2c_chan *chan;
 131
 132         chan = kzalloc(sizeof(struct intel_i2c_chan), GFP_KERNEL);
 133         if (!chan)
 134                 goto out_free;
 135
 136         chan->drm_dev = dev;
 137         chan->reg = reg;
 138         snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name);
 139         chan->adapter.owner = THIS_MODULE;
 140         chan->adapter.algo_data = &chan->algo;
 141         chan->adapter.dev.parent = &dev->pdev->dev;
 142         chan->algo.setsda = set_data;
 143         chan->algo.setscl = set_clock;
 144         chan->algo.getsda = get_data;
 145         chan->algo.getscl = get_clock;
 146         chan->algo.udelay = 20;
 147         chan->algo.timeout = usecs_to_jiffies(2200);
 148         chan->algo.data = chan;
 149
 150         i2c_set_adapdata(&chan->adapter, chan);
 151
 152         if(i2c_bit_add_bus(&chan->adapter))
 153                 goto out_free;
 154
 155         /* JJJ:  raise SCL and SDA? */
 156         set_data(chan, 1);
 157         set_clock(chan, 1);
 158         udelay(20);
 159
 160         return chan;
 161
 162 out_free:
 163         kfree(chan);
 164         return NULL;
 165 }
 166
 167 /**
 168  * intel_i2c_destroy - unregister and free i2c bus resources
 169  * @output: channel to free
 170  *
 171  * Unregister the adapter from the i2c layer, then free the structure.
 172  */
 173 void intel_i2c_destroy(struct intel_i2c_chan *chan)
 174 {
 175         if (!chan)
 176                 return;
 177
 178         i2c_del_adapter(&chan->adapter);
 179         kfree(chan);
 180 }