drivers/i2c/busses/i2c-ixp4xx.c

   1 /*
   2  * drivers/i2c/busses/i2c-ixp4xx.c
   3  *
   4  * Intel's IXP42x XScale NPU chipsets (IXP420, 421, 422, 425) do not have
   5  * an on board I2C controller but provide 16 GPIO pins that are often
   6  * used to create an I2C bus. This driver provides an i2c_adapter
   7  * interface that plugs in under algo_bit and drives the GPIO pins
   8  * as instructed by the alogorithm driver.
   9  *
  10  * Author: Deepak Saxena <dsaxena@plexity.net>
  11  *
  12  * Copyright (c) 2003-2004 MontaVista Software Inc.
  13  *
  14  * This file is licensed under the terms of the GNU General Public
  15  * License version 2. This program is licensed "as is" without any
  16  * warranty of any kind, whether express or implied.
  17  *
  18  * NOTE: Since different platforms will use different GPIO pins for
  19  *       I2C, this driver uses an IXP42x-specific platform_data
  20  *       pointer to pass the GPIO numbers to the driver. This
  21  *       allows us to support all the different IXP42x platforms
  22  *       w/o having to put #ifdefs in this driver.
  23  *
  24  *       See arch/arm/mach-ixp42x/ixdp425.c for an example of building a
  25  *       device list and filling in the ixp4xx_i2c_pins data structure
  26  *       that is passed as the platform_data to this driver.
  27  */
  28
  29 #include <linux/kernel.h>
  30 #include <linux/init.h>
  31 #include <linux/platform_device.h>
  32 #include <linux/module.h>
  33 #include <linux/i2c.h>
  34 #include <linux/i2c-algo-bit.h>
  35 #include <linux/i2c-id.h>
  36
  37 #include <asm/hardware.h>       /* Pick up IXP42x-specific bits */
  38
  39 static inline int ixp42x_scl_pin(void *data)
  40 {
  41         return ((struct ixp4xx_i2c_pins*)data)->scl_pin;
  42 }
  43
  44 static inline int ixp42x_sda_pin(void *data)
  45 {
  46         return ((struct ixp4xx_i2c_pins*)data)->sda_pin;
  47 }
  48
  49 static void ixp42x_bit_setscl(void *data, int val)
  50 {
  51         gpio_line_set(ixp42x_scl_pin(data), 0);
  52         gpio_line_config(ixp42x_scl_pin(data),
  53                 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
  54 }
  55
  56 static void ixp42x_bit_setsda(void *data, int val)
  57 {
  58         gpio_line_set(ixp42x_sda_pin(data), 0);
  59         gpio_line_config(ixp42x_sda_pin(data),
  60                 val ? IXP4XX_GPIO_IN : IXP4XX_GPIO_OUT );
  61 }
  62
  63 static int ixp42x_bit_getscl(void *data)
  64 {
  65         int scl;
  66
  67         gpio_line_config(ixp42x_scl_pin(data), IXP4XX_GPIO_IN );
  68         gpio_line_get(ixp42x_scl_pin(data), &scl);
  69
  70         return scl;
  71 }
  72
  73 static int ixp42x_bit_getsda(void *data)
  74 {
  75         int sda;
  76
  77         gpio_line_config(ixp42x_sda_pin(data), IXP4XX_GPIO_IN );
  78         gpio_line_get(ixp42x_sda_pin(data), &sda);
  79
  80         return sda;
  81 }
  82
  83 struct ixp4xx_i2c_data {
  84         struct ixp4xx_i2c_pins *gpio_pins;
  85         struct i2c_adapter adapter;
  86         struct i2c_algo_bit_data algo_data;
  87 };
  88
  89 static int ixp4xx_i2c_remove(struct platform_device *plat_dev)
  90 {
  91         struct ixp4xx_i2c_data *drv_data = platform_get_drvdata(plat_dev);
  92
  93         platform_set_drvdata(plat_dev, NULL);
  94
  95         i2c_bit_del_bus(&drv_data->adapter);
  96
  97         kfree(drv_data);
  98
  99         return 0;
 100 }
 101
 102 static int ixp4xx_i2c_probe(struct platform_device *plat_dev)
 103 {
 104         int err;
 105         struct ixp4xx_i2c_pins *gpio = plat_dev->dev.platform_data;
 106         struct ixp4xx_i2c_data *drv_data =
 107                 kzalloc(sizeof(struct ixp4xx_i2c_data), GFP_KERNEL);
 108
 109         if(!drv_data)
 110                 return -ENOMEM;
 111
 112         drv_data->gpio_pins = gpio;
 113
 114         /*
 115          * We could make a lot of these structures static, but
 116          * certain platforms may have multiple GPIO-based I2C
 117          * buses for various device domains, so we need per-device
 118          * algo_data->data.
 119          */
 120         drv_data->algo_data.data = gpio;
 121         drv_data->algo_data.setsda = ixp42x_bit_setsda;
 122         drv_data->algo_data.setscl = ixp42x_bit_setscl;
 123         drv_data->algo_data.getsda = ixp42x_bit_getsda;
 124         drv_data->algo_data.getscl = ixp42x_bit_getscl;
 125         drv_data->algo_data.udelay = 10;
 126         drv_data->algo_data.timeout = 100;
 127
 128         drv_data->adapter.id = I2C_HW_B_IXP4XX;
 129         drv_data->adapter.class = I2C_CLASS_HWMON;
 130         strlcpy(drv_data->adapter.name, plat_dev->dev.driver->name,
 131                 I2C_NAME_SIZE);
 132         drv_data->adapter.algo_data = &drv_data->algo_data;
 133
 134         drv_data->adapter.dev.parent = &plat_dev->dev;
 135
 136         gpio_line_config(gpio->scl_pin, IXP4XX_GPIO_IN);
 137         gpio_line_config(gpio->sda_pin, IXP4XX_GPIO_IN);
 138         gpio_line_set(gpio->scl_pin, 0);
 139         gpio_line_set(gpio->sda_pin, 0);
 140
 141         err = i2c_bit_add_bus(&drv_data->adapter);
 142         if (err) {
 143                 printk(KERN_ERR "ERROR: Could not install %s\n", plat_dev->dev.bus_id);
 144
 145                 kfree(drv_data);
 146                 return err;
 147         }
 148
 149         platform_set_drvdata(plat_dev, drv_data);
 150
 151         return 0;
 152 }
 153
 154 static struct platform_driver ixp4xx_i2c_driver = {
 155         .probe          = ixp4xx_i2c_probe,
 156         .remove         = ixp4xx_i2c_remove,
 157         .driver         = {
 158                 .name   = "IXP4XX-I2C",
 159                 .owner  = THIS_MODULE,
 160         },
 161 };
 162
 163 static int __init ixp42x_i2c_init(void)
 164 {
 165         return platform_driver_register(&ixp4xx_i2c_driver);
 166 }
 167
 168 static void __exit ixp42x_i2c_exit(void)
 169 {
 170         platform_driver_unregister(&ixp4xx_i2c_driver);
 171 }
 172
 173 module_init(ixp42x_i2c_init);
 174 module_exit(ixp42x_i2c_exit);
 175
 176 MODULE_DESCRIPTION("GPIO-based I2C driver for IXP42x systems");
 177 MODULE_LICENSE("GPL");
 178 MODULE_AUTHOR("Deepak Saxena <dsaxena@plexity.net>");
 179