drivers/gpu/drm/gma500/intel_i2c.c

   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 psb_intel_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 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_DATA_VAL_IN) != 0;
  41 }
  42
  43 static void set_clock(void *data, int state_high)
  44 {
  45         struct psb_intel_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 psb_intel_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  * psb_intel_i2c_create - instantiate an Intel i2c bus using the specified GPIO reg
  87  * @dev: DRM device
  88  * @output: driver specific output device
  89  * @reg: GPIO reg to use
  90  * @name: name for this bus
  91  *
  92  * Creates and registers a new i2c bus with the Linux i2c layer, for use
  93  * in output probing and control (e.g. DDC or SDVO control functions).
  94  *
  95  * Possible values for @reg include:
  96  *   %GPIOA
  97  *   %GPIOB
  98  *   %GPIOC
  99  *   %GPIOD
 100  *   %GPIOE
 101  *   %GPIOF
 102  *   %GPIOG
 103  *   %GPIOH
 104  * see PRM for details on how these different busses are used.
 105  */
 106 struct psb_intel_i2c_chan *psb_intel_i2c_create(struct drm_device *dev,
 107                                         const u32 reg, const char *name)
 108 {
 109         struct psb_intel_i2c_chan *chan;
 110
 111         chan = kzalloc(sizeof(struct psb_intel_i2c_chan), GFP_KERNEL);
 112         if (!chan)
 113                 goto out_free;
 114
 115         chan->drm_dev = dev;
 116         chan->reg = reg;
 117         snprintf(chan->adapter.name, I2C_NAME_SIZE, "intel drm %s", name);
 118         chan->adapter.owner = THIS_MODULE;
 119         chan->adapter.algo_data = &chan->algo;
 120         chan->adapter.dev.parent = &dev->pdev->dev;
 121         chan->algo.setsda = set_data;
 122         chan->algo.setscl = set_clock;
 123         chan->algo.getsda = get_data;
 124         chan->algo.getscl = get_clock;
 125         chan->algo.udelay = 20;
 126         chan->algo.timeout = usecs_to_jiffies(2200);
 127         chan->algo.data = chan;
 128
 129         i2c_set_adapdata(&chan->adapter, chan);
 130
 131         if (i2c_bit_add_bus(&chan->adapter))
 132                 goto out_free;
 133
 134         /* JJJ:  raise SCL and SDA? */
 135         set_data(chan, 1);
 136         set_clock(chan, 1);
 137         udelay(20);
 138
 139         return chan;
 140
 141 out_free:
 142         kfree(chan);
 143         return NULL;
 144 }
 145
 146 /**
 147  * psb_intel_i2c_destroy - unregister and free i2c bus resources
 148  * @output: channel to free
 149  *
 150  * Unregister the adapter from the i2c layer, then free the structure.
 151  */
 152 void psb_intel_i2c_destroy(struct psb_intel_i2c_chan *chan)
 153 {
 154         if (!chan)
 155                 return;
 156
 157         i2c_del_adapter(&chan->adapter);
 158         kfree(chan);
 159 }