drivers/staging/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
  21 #include <linux/i2c.h>
  22 #include <linux/i2c-algo-bit.h>
  23 #include <linux/export.h>
  24
  25 #include "psb_drv.h"
  26 #include "psb_intel_reg.h"
  27
  28 /*
  29  * Intel GPIO access functions
  30  */
  31
  32 #define I2C_RISEFALL_TIME 20
  33
  34 static int get_clock(void *data)
  35 {
  36         struct psb_intel_i2c_chan *chan = data;
  37         struct drm_device *dev = chan->drm_dev;
  38         u32 val;
  39
  40         val = REG_READ(chan->reg);
  41         return (val & GPIO_CLOCK_VAL_IN) != 0;
  42 }
  43
  44 static int get_data(void *data)
  45 {
  46         struct psb_intel_i2c_chan *chan = data;
  47         struct drm_device *dev = chan->drm_dev;
  48         u32 val;
  49
  50         val = REG_READ(chan->reg);
  51         return (val & GPIO_DATA_VAL_IN) != 0;
  52 }
  53
  54 static void set_clock(void *data, int state_high)
  55 {
  56         struct psb_intel_i2c_chan *chan = data;
  57         struct drm_device *dev = chan->drm_dev;
  58         u32 reserved = 0, clock_bits;
  59
  60         /* On most chips, these bits must be preserved in software. */
  61         reserved =
  62                     REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
  63                                            GPIO_CLOCK_PULLUP_DISABLE);
  64
  65         if (state_high)
  66                 clock_bits = GPIO_CLOCK_DIR_IN | GPIO_CLOCK_DIR_MASK;
  67         else
  68                 clock_bits = GPIO_CLOCK_DIR_OUT | GPIO_CLOCK_DIR_MASK |
  69                     GPIO_CLOCK_VAL_MASK;
  70         REG_WRITE(chan->reg, reserved | clock_bits);
  71         udelay(I2C_RISEFALL_TIME);      /* wait for the line to change state */
  72 }
  73
  74 static void set_data(void *data, int state_high)
  75 {
  76         struct psb_intel_i2c_chan *chan = data;
  77         struct drm_device *dev = chan->drm_dev;
  78         u32 reserved = 0, data_bits;
  79
  80         /* On most chips, these bits must be preserved in software. */
  81         reserved =
  82                     REG_READ(chan->reg) & (GPIO_DATA_PULLUP_DISABLE |
  83                                            GPIO_CLOCK_PULLUP_DISABLE);
  84
  85         if (state_high)
  86                 data_bits = GPIO_DATA_DIR_IN | GPIO_DATA_DIR_MASK;
  87         else
  88                 data_bits =
  89                     GPIO_DATA_DIR_OUT | GPIO_DATA_DIR_MASK |
  90                     GPIO_DATA_VAL_MASK;
  91
  92         REG_WRITE(chan->reg, reserved | data_bits);
  93         udelay(I2C_RISEFALL_TIME);      /* wait for the line to change state */
  94 }
  95
  96 /**
  97  * psb_intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
  98  * @dev: DRM device
  99  * @output: driver specific output device
 100  * @reg: GPIO reg to use
 101  * @name: name for this bus
 102  *
 103  * Creates and registers a new i2c bus with the Linux i2c layer, for use
 104  * in output probing and control (e.g. DDC or SDVO control functions).
 105  *
 106  * Possible values for @reg include:
 107  *   %GPIOA
 108  *   %GPIOB
 109  *   %GPIOC
 110  *   %GPIOD
 111  *   %GPIOE
 112  *   %GPIOF
 113  *   %GPIOG
 114  *   %GPIOH
 115  * see PRM for details on how these different busses are used.
 116  */
 117 struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev,
 118                                         const u32 reg, const char *name)
 119 {
 120         struct psb_intel_i2c_chan *chan;
 121
 122         chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL);
 123         if (!chan)
 124                 goto out_free;
 125
 126         chan->drm_dev = dev;
 127         chan->reg = reg;
 128         snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name);
 129         chan->adapter.owner = THIS_MODULE;
 130         chan->adapter.algo_data = &chan->algo;
 131         chan->adapter.dev.parent = &dev->pdev->dev;
 132         chan->algo.setsda = set_data;
 133         chan->algo.setscl = set_clock;
 134         chan->algo.getsda = get_data;
 135         chan->algo.getscl = get_clock;
 136         chan->algo.udelay = 20;
 137         chan->algo.timeout = usecs_to_jiffies(2200);
 138         chan->algo.data = chan;
 139
 140         i2c_set_adapdata(&chan->adapter, chan);
 141
 142         if (i2c_bit_add_bus(&chan->adapter))
 143                 goto out_free;
 144
 145         /* JJJ:  raise SCL and SDA? */
 146         set_data(chan, 1);
 147         set_clock(chan, 1);
 148         udelay(20);
 149
 150         return chan;
 151
 152 out_free:
 153         kfree(chan);
 154         return NULL;
 155 }
 156
 157 /**
 158  * psb_intel_i2c_destroy - unregister and free i2c bus resources
 159  * @output: channel to free
 160  *
 161  * Unregister the adapter from the i2c layer, then free the structure.
 162  */
 163 void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan)
 164 {
 165         if (!chan)
 166                 return;
 167
 168         i2c_del_adapter(&chan->adapter);
 169         kfree(chan);
 170 }