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191 lines
4.7 KiB
C
191 lines
4.7 KiB
C
/*
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* Custom GPIO-based I2C driver
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*
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* Copyright (C) 2007 Gabor Juhos <juhosg at openwrt.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* ---------------------------------------------------------------------------
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*
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* The behaviour of this driver can be altered by setting some parameters
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* from the insmod command line.
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*
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* The following parameters are adjustable:
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*
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* bus0 These four arguments can be arrays of
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* bus1 1-8 unsigned integers as follows:
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* bus2
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* bus3 <id>,<sda>,<scl>,<udelay>,<timeout>,<sda_od>,<scl_od>,<scl_oo>
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*
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* where:
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*
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* <id> ID to used as device_id for the corresponding bus (required)
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* <sda> GPIO pin ID to used for SDA (required)
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* <scl> GPIO pin ID to used for SCL (required)
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* <udelay> signal toggle delay.
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* <timeout> clock stretching timeout.
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* <sda_od> SDA is configured as open drain.
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* <scl_od> SCL is configured as open drain.
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* <scl_oo> SCL output drivers cannot be turned off.
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*
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* See include/i2c-gpio.h for more information about the parameters.
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*
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* If this driver is built into the kernel, you can use the following kernel
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* command line parameters, with the same values as the corresponding module
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* parameters listed above:
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*
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* i2c-gpio-custom.bus0
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* i2c-gpio-custom.bus1
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* i2c-gpio-custom.bus2
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* i2c-gpio-custom.bus3
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/platform_device.h>
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#include <linux/i2c-gpio.h>
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#define DRV_NAME "i2c-gpio-custom"
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#define DRV_DESC "Custom GPIO-based I2C driver"
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#define DRV_VERSION "0.1.0"
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#define PFX DRV_NAME ": "
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#define BUS_PARAM_ID 0
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#define BUS_PARAM_SDA 1
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#define BUS_PARAM_SCL 2
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#define BUS_PARAM_UDELAY 3
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#define BUS_PARAM_TIMEOUT 4
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#define BUS_PARAM_SDA_OD 5
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#define BUS_PARAM_SCL_OD 6
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#define BUS_PARAM_SCL_OO 7
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#define BUS_PARAM_REQUIRED 3
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#define BUS_PARAM_COUNT 8
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#define BUS_COUNT_MAX 4
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static unsigned int bus0[BUS_PARAM_COUNT] __initdata;
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static unsigned int bus1[BUS_PARAM_COUNT] __initdata;
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static unsigned int bus2[BUS_PARAM_COUNT] __initdata;
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static unsigned int bus3[BUS_PARAM_COUNT] __initdata;
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static unsigned int bus_nump[BUS_COUNT_MAX] __initdata;
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#define BUS_PARM_DESC \
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" config -> id,sda,scl[,udelay,timeout,sda_od,scl_od,scl_oo]"
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module_param_array(bus0, uint, &bus_nump[0], 0);
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MODULE_PARM_DESC(bus0, "bus0" BUS_PARM_DESC);
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module_param_array(bus1, uint, &bus_nump[1], 0);
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MODULE_PARM_DESC(bus1, "bus1" BUS_PARM_DESC);
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module_param_array(bus2, uint, &bus_nump[2], 0);
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MODULE_PARM_DESC(bus2, "bus2" BUS_PARM_DESC);
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module_param_array(bus3, uint, &bus_nump[3], 0);
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MODULE_PARM_DESC(bus3, "bus3" BUS_PARM_DESC);
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static struct platform_device *devices[BUS_COUNT_MAX];
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static unsigned int nr_devices;
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static void i2c_gpio_custom_cleanup(void)
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{
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int i;
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for (i = 0; i < nr_devices; i++)
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if (devices[i])
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platform_device_unregister(devices[i]);
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}
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static int __init i2c_gpio_custom_add_one(unsigned int id, unsigned int *params)
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{
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struct platform_device *pdev;
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struct i2c_gpio_platform_data pdata;
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int err;
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if (!bus_nump[id])
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return 0;
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if (bus_nump[id] < BUS_PARAM_REQUIRED) {
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printk(KERN_ERR PFX "not enough parameters for bus%d\n", id);
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err = -EINVAL;
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goto err;
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}
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pdev = platform_device_alloc("i2c-gpio", params[BUS_PARAM_ID]);
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if (!pdev) {
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err = -ENOMEM;
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goto err;
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}
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devices[nr_devices++] = pdev;
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pdata.sda_pin = params[BUS_PARAM_SDA];
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pdata.scl_pin = params[BUS_PARAM_SCL];
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pdata.udelay = params[BUS_PARAM_UDELAY];
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pdata.timeout = params[BUS_PARAM_TIMEOUT];
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pdata.sda_is_open_drain = params[BUS_PARAM_SDA_OD] != 0;
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pdata.scl_is_open_drain = params[BUS_PARAM_SCL_OD] != 0;
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pdata.scl_is_output_only = params[BUS_PARAM_SCL_OO] != 0;
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err = platform_device_add_data(pdev, &pdata, sizeof(pdata));
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if (err)
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goto err;
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err = platform_device_register(pdev);
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if (err)
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goto err;
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return 0;
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err:
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return err;
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}
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static int __init i2c_gpio_custom_init(void)
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{
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int err;
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printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");
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err = i2c_gpio_custom_add_one(0, bus0);
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if (err) goto err;
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err = i2c_gpio_custom_add_one(1, bus1);
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if (err) goto err;
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err = i2c_gpio_custom_add_one(2, bus2);
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if (err) goto err;
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err = i2c_gpio_custom_add_one(3, bus3);
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if (err) goto err;
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if (!nr_devices) {
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printk(KERN_ERR PFX "no bus parameter(s) specified\n");
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err = -ENODEV;
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goto err;
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}
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return 0;
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err:
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i2c_gpio_custom_cleanup();
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return err;
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}
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module_init(i2c_gpio_custom_init);
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static void __exit i2c_gpio_custom_exit(void)
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{
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i2c_gpio_custom_cleanup();
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}
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module_exit(i2c_gpio_custom_exit);
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MODULE_LICENSE("GPL v2");
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MODULE_AUTHOR("Gabor Juhos <juhosg at openwrt.org >");
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MODULE_DESCRIPTION(DRV_DESC);
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MODULE_VERSION(DRV_VERSION);
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