package/i2c-gpio-custom/src/i2c-gpio-custom.c

   1 /*
   2  *  Custom GPIO-based I2C driver
   3  *
   4  *  Copyright (C) 2007 Gabor Juhos <juhosg at openwrt.org>
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License version 2 as
   8  *  published by the Free Software Foundation.
   9  *
  10  * ---------------------------------------------------------------------------
  11  *
  12  *  The behaviour of this driver can be altered by setting some parameters
  13  *  from the insmod command line.
  14  *
  15  *  The following parameters are adjustable:
  16  *
  17  *      bus0    These four arguments can be arrays of
  18  *      bus1    1-8 unsigned integers as follows:
  19  *      bus2
  20  *      bus3    <id>,<sda>,<scl>,<udelay>,<timeout>,<sda_od>,<scl_od>,<scl_oo>
  21  *
  22  *  where:
  23  *
  24  *  <id>        ID to used as device_id for the corresponding bus (required)
  25  *  <sda>       GPIO pin ID to used for SDA (required)
  26  *  <scl>       GPIO pin ID to used for SCL (required)
  27  *  <udelay>    signal toggle delay.
  28  *  <timeout>   clock stretching timeout.
  29  *  <sda_od>    SDA is configured as open drain.
  30  *  <scl_od>    SCL is configured as open drain.
  31  *  <scl_oo>    SCL output drivers cannot be turned off.
  32  *
  33  *  See include/i2c-gpio.h for more information about the parameters.
  34  *
  35  *  If this driver is built into the kernel, you can use the following kernel
  36  *  command line parameters, with the same values as the corresponding module
  37  *  parameters listed above:
  38  *
  39  *      i2c-gpio-custom.bus0
  40  *      i2c-gpio-custom.bus1
  41  *      i2c-gpio-custom.bus2
  42  *      i2c-gpio-custom.bus3
  43  */
  44
  45 #include <linux/kernel.h>
  46 #include <linux/module.h>
  47 #include <linux/init.h>
  48 #include <linux/platform_device.h>
  49
  50 #include <linux/i2c-gpio.h>
  51
  52 #define DRV_NAME        "i2c-gpio-custom"
  53 #define DRV_DESC        "Custom GPIO-based I2C driver"
  54 #define DRV_VERSION     "0.1.0"
  55
  56 #define PFX             DRV_NAME ": "
  57
  58 #define BUS_PARAM_ID            0
  59 #define BUS_PARAM_SDA           1
  60 #define BUS_PARAM_SCL           2
  61 #define BUS_PARAM_UDELAY        3
  62 #define BUS_PARAM_TIMEOUT       4
  63 #define BUS_PARAM_SDA_OD        5
  64 #define BUS_PARAM_SCL_OD        6
  65 #define BUS_PARAM_SCL_OO        7
  66
  67 #define BUS_PARAM_REQUIRED      3
  68 #define BUS_PARAM_COUNT         8
  69 #define BUS_COUNT_MAX           4
  70
  71 static unsigned int bus0[BUS_PARAM_COUNT] __initdata;
  72 static unsigned int bus1[BUS_PARAM_COUNT] __initdata;
  73 static unsigned int bus2[BUS_PARAM_COUNT] __initdata;
  74 static unsigned int bus3[BUS_PARAM_COUNT] __initdata;
  75
  76 static unsigned int bus_nump[BUS_COUNT_MAX] __initdata;
  77
  78 #define BUS_PARM_DESC \
  79         " config -> id,sda,scl[,udelay,timeout,sda_od,scl_od,scl_oo]"
  80
  81 module_param_array(bus0, uint, &bus_nump[0], 0);
  82 MODULE_PARM_DESC(bus0, "bus0" BUS_PARM_DESC);
  83 module_param_array(bus1, uint, &bus_nump[1], 0);
  84 MODULE_PARM_DESC(bus1, "bus1" BUS_PARM_DESC);
  85 module_param_array(bus2, uint, &bus_nump[2], 0);
  86 MODULE_PARM_DESC(bus2, "bus2" BUS_PARM_DESC);
  87 module_param_array(bus3, uint, &bus_nump[3], 0);
  88 MODULE_PARM_DESC(bus3, "bus3" BUS_PARM_DESC);
  89
  90 static struct platform_device *devices[BUS_COUNT_MAX];
  91 static unsigned int nr_devices;
  92
  93 static void i2c_gpio_custom_cleanup(void)
  94 {
  95         int i;
  96
  97         for (i = 0; i < nr_devices; i++)
  98                 if (devices[i])
  99                         platform_device_unregister(devices[i]);
 100 }
 101
 102 static int __init i2c_gpio_custom_add_one(unsigned int id, unsigned int *params)
 103 {
 104         struct platform_device *pdev;
 105         struct i2c_gpio_platform_data pdata;
 106         int err;
 107
 108         if (!bus_nump[id])
 109                 return 0;
 110
 111         if (bus_nump[id] < BUS_PARAM_REQUIRED) {
 112                 printk(KERN_ERR PFX "not enough parameters for bus%d\n", id);
 113                 err = -EINVAL;
 114                 goto err;
 115         }
 116
 117         pdev = platform_device_alloc("i2c-gpio", params[BUS_PARAM_ID]);
 118         if (!pdev) {
 119                 err = -ENOMEM;
 120                 goto err;
 121         }
 122
 123         devices[nr_devices++] = pdev;
 124
 125         pdata.sda_pin = params[BUS_PARAM_SDA];
 126         pdata.scl_pin = params[BUS_PARAM_SCL];
 127         pdata.udelay = params[BUS_PARAM_UDELAY];
 128         pdata.timeout = params[BUS_PARAM_TIMEOUT];
 129         pdata.sda_is_open_drain = params[BUS_PARAM_SDA_OD] != 0;
 130         pdata.scl_is_open_drain = params[BUS_PARAM_SCL_OD] != 0;
 131         pdata.scl_is_output_only = params[BUS_PARAM_SCL_OO] != 0;
 132
 133         err = platform_device_add_data(pdev, &pdata, sizeof(pdata));
 134         if (err)
 135                 goto err;
 136
 137         err = platform_device_register(pdev);
 138         if (err)
 139                 goto err;
 140
 141         return 0;
 142
 143 err:
 144         return err;
 145 }
 146
 147 static int __init i2c_gpio_custom_probe(void)
 148 {
 149         int err;
 150
 151         printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");
 152
 153         err = i2c_gpio_custom_add_one(0, bus0);
 154         if (err) goto err;
 155
 156         err = i2c_gpio_custom_add_one(1, bus1);
 157         if (err) goto err;
 158
 159         err = i2c_gpio_custom_add_one(2, bus2);
 160         if (err) goto err;
 161
 162         err = i2c_gpio_custom_add_one(3, bus3);
 163         if (err) goto err;
 164
 165         if (!nr_devices) {
 166                 printk(KERN_ERR PFX "no bus parameter(s) specified\n");
 167                 err = -ENODEV;
 168                 goto err;
 169         }
 170
 171         return 0;
 172
 173 err:
 174         i2c_gpio_custom_cleanup();
 175         return err;
 176 }
 177
 178 #ifdef MODULE
 179 static int __init i2c_gpio_custom_init(void)
 180 {
 181         return i2c_gpio_custom_probe();
 182 }
 183 module_init(i2c_gpio_custom_init);
 184
 185 static void __exit i2c_gpio_custom_exit(void)
 186 {
 187         i2c_gpio_custom_cleanup();
 188 }
 189 module_exit(i2c_gpio_custom_exit);
 190 #else
 191 subsys_initcall(i2c_gpio_custom_probe);
 192 #endif /* MODULE*/
 193
 194 MODULE_LICENSE("GPL v2");
 195 MODULE_AUTHOR("Gabor Juhos <juhosg at openwrt.org >");
 196 MODULE_DESCRIPTION(DRV_DESC);
 197 MODULE_VERSION(DRV_VERSION);