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

   1 /*
   2  *  Custom GPIO-based I2C driver
   3  *
   4  *  Copyright (C) 2007-2008 Gabor Juhos <juhosg@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/version.h>
  51 #if LINUX_VERSION_CODE < KERNEL_VERSION(4, 18, 0)
  52 #include <linux/i2c-gpio.h>
  53 #else
  54 #include <linux/platform_data/i2c-gpio.h>
  55 #endif
  56
  57 #define DRV_NAME        "i2c-gpio-custom"
  58 #define DRV_DESC        "Custom GPIO-based I2C driver"
  59 #define DRV_VERSION     "0.1.1"
  60
  61 #define PFX             DRV_NAME ": "
  62
  63 #define BUS_PARAM_ID            0
  64 #define BUS_PARAM_SDA           1
  65 #define BUS_PARAM_SCL           2
  66 #define BUS_PARAM_UDELAY        3
  67 #define BUS_PARAM_TIMEOUT       4
  68 #define BUS_PARAM_SDA_OD        5
  69 #define BUS_PARAM_SCL_OD        6
  70 #define BUS_PARAM_SCL_OO        7
  71
  72 #define BUS_PARAM_REQUIRED      3
  73 #define BUS_PARAM_COUNT         8
  74 #define BUS_COUNT_MAX           4
  75
  76 static unsigned int bus0[BUS_PARAM_COUNT] __initdata;
  77 static unsigned int bus1[BUS_PARAM_COUNT] __initdata;
  78 static unsigned int bus2[BUS_PARAM_COUNT] __initdata;
  79 static unsigned int bus3[BUS_PARAM_COUNT] __initdata;
  80
  81 static unsigned int bus_nump[BUS_COUNT_MAX] __initdata;
  82
  83 #define BUS_PARM_DESC \
  84         " config -> id,sda,scl[,udelay,timeout,sda_od,scl_od,scl_oo]"
  85
  86 module_param_array(bus0, uint, &bus_nump[0], 0);
  87 MODULE_PARM_DESC(bus0, "bus0" BUS_PARM_DESC);
  88 module_param_array(bus1, uint, &bus_nump[1], 0);
  89 MODULE_PARM_DESC(bus1, "bus1" BUS_PARM_DESC);
  90 module_param_array(bus2, uint, &bus_nump[2], 0);
  91 MODULE_PARM_DESC(bus2, "bus2" BUS_PARM_DESC);
  92 module_param_array(bus3, uint, &bus_nump[3], 0);
  93 MODULE_PARM_DESC(bus3, "bus3" BUS_PARM_DESC);
  94
  95 static struct platform_device *devices[BUS_COUNT_MAX];
  96 static unsigned int nr_devices;
  97
  98 static void i2c_gpio_custom_cleanup(void)
  99 {
 100         int i;
 101
 102         for (i = 0; i < nr_devices; i++)
 103                 if (devices[i])
 104                         platform_device_put(devices[i]);
 105 }
 106
 107 static int __init i2c_gpio_custom_add_one(unsigned int id, unsigned int *params)
 108 {
 109         struct platform_device *pdev;
 110         struct i2c_gpio_platform_data pdata;
 111         int err;
 112
 113         if (!bus_nump[id])
 114                 return 0;
 115
 116         if (bus_nump[id] < BUS_PARAM_REQUIRED) {
 117                 printk(KERN_ERR PFX "not enough parameters for bus%d\n", id);
 118                 err = -EINVAL;
 119                 goto err;
 120         }
 121
 122         pdev = platform_device_alloc("i2c-gpio", params[BUS_PARAM_ID]);
 123         if (!pdev) {
 124                 err = -ENOMEM;
 125                 goto err;
 126         }
 127
 128         pdata.sda_pin = params[BUS_PARAM_SDA];
 129         pdata.scl_pin = params[BUS_PARAM_SCL];
 130         pdata.udelay = params[BUS_PARAM_UDELAY];
 131         pdata.timeout = params[BUS_PARAM_TIMEOUT];
 132         pdata.sda_is_open_drain = params[BUS_PARAM_SDA_OD] != 0;
 133         pdata.scl_is_open_drain = params[BUS_PARAM_SCL_OD] != 0;
 134         pdata.scl_is_output_only = params[BUS_PARAM_SCL_OO] != 0;
 135
 136         err = platform_device_add_data(pdev, &pdata, sizeof(pdata));
 137         if (err)
 138                 goto err_put;
 139
 140         err = platform_device_add(pdev);
 141         if (err)
 142                 goto err_put;
 143
 144         devices[nr_devices++] = pdev;
 145         return 0;
 146
 147 err_put:
 148         platform_device_put(pdev);
 149 err:
 150         return err;
 151 }
 152
 153 static int __init i2c_gpio_custom_probe(void)
 154 {
 155         int err;
 156
 157         printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");
 158
 159         err = i2c_gpio_custom_add_one(0, bus0);
 160         if (err)
 161                 goto err;
 162
 163         err = i2c_gpio_custom_add_one(1, bus1);
 164         if (err)
 165                 goto err;
 166
 167         err = i2c_gpio_custom_add_one(2, bus2);
 168         if (err)
 169                 goto err;
 170
 171         err = i2c_gpio_custom_add_one(3, bus3);
 172         if (err)
 173                 goto err;
 174
 175         if (!nr_devices) {
 176                 printk(KERN_ERR PFX "no bus parameter(s) specified\n");
 177                 err = -ENODEV;
 178                 goto err;
 179         }
 180
 181         return 0;
 182
 183 err:
 184         i2c_gpio_custom_cleanup();
 185         return err;
 186 }
 187
 188 #ifdef MODULE
 189 static int __init i2c_gpio_custom_init(void)
 190 {
 191         return i2c_gpio_custom_probe();
 192 }
 193 module_init(i2c_gpio_custom_init);
 194
 195 static void __exit i2c_gpio_custom_exit(void)
 196 {
 197         i2c_gpio_custom_cleanup();
 198 }
 199 module_exit(i2c_gpio_custom_exit);
 200 #else
 201 subsys_initcall(i2c_gpio_custom_probe);
 202 #endif /* MODULE*/
 203
 204 MODULE_LICENSE("GPL v2");
 205 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org >");
 206 MODULE_DESCRIPTION(DRV_DESC);
 207 MODULE_VERSION(DRV_VERSION);