drivers/gpu/drm/gma500/intel_i2c.c

   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 }