text: /* ------------------------------------------------------------------------ *
   * i2c-parport-light.c I2C bus over parallel port                           *
   * ------------------------------------------------------------------------ *
     Copyright (C) 2003-2010 Jean Delvare <jdelvare@suse.de>
  
     Based on older i2c-velleman.c driver
     Copyright (C) 1995-2000 Simon G. Vogl
     With some changes from:
     Frodo Looijaard <frodol@dds.nl>
     Kyösti Mälkki <kmalkki@cc.hut.fi>
  
     This program is free software; you can redistribute it and/or modify
     it under the terms of the GNU General Public License as published by
     the Free Software Foundation; either version 2 of the License, or
     (at your option) any later version.
  
     This program is distributed in the hope that it will be useful,
     but WITHOUT ANY WARRANTY; without even the implied warranty of
     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     GNU General Public License for more details.
   * ------------------------------------------------------------------------ */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/delay.h>
  #include <linux/platform_device.h>
  #include <linux/ioport.h>
  #include <linux/i2c.h>
  #include <linux/i2c-algo-bit.h>
  #include <linux/i2c-smbus.h>
  #include <linux/io.h>
  #include "i2c-parport.h"
  
  #define DEFAULT_BASE 0x378
  #define DRVNAME "i2c-parport-light"
  
  static struct platform_device *pdev;
  
  static u16 base;
  module_param(base, ushort, 0);
  MODULE_PARM_DESC(base, "Base I/O address");
  
  static int irq;
  module_param(irq, int, 0);
  MODULE_PARM_DESC(irq, "IRQ (optional)");
  
  /* ----- Low-level parallel port access ----------------------------------- */
  
  static inline void port_write(unsigned char p, unsigned char d)
  {
  	outb(d, base+p);
  }
  
  static inline unsigned char port_read(unsigned char p)
  {
  	return inb(base+p);
  }
  
  /* ----- Unified line operation functions --------------------------------- */
  
  static inline void line_set(int state, const struct lineop *op)
  {
  	u8 oldval = port_read(op->port);
  
  	/* Touch only the bit(s) needed */
  	if ((op->inverted && !state) || (!op->inverted && state))
  		port_write(op->port, oldval | op->val);
  	else
  		port_write(op->port, oldval & ~op->val);
  }
  
  static inline int line_get(const struct lineop *op)
  {
  	u8 oldval = port_read(op->port);
  
  	return ((op->inverted && (oldval & op->val) != op->val)
  	    || (!op->inverted && (oldval & op->val) == op->val));
  }
  
  /* ----- I2C algorithm call-back functions and structures ----------------- */
  
  static void parport_setscl(void *data, int state)
  {
  	line_set(state, &adapter_parm[type].setscl);
  }
  
  static void parport_setsda(void *data, int state)
  {
  	line_set(state, &adapter_parm[type].setsda);
  }
  
  static int parport_getscl(void *data)
  {
  	return line_get(&adapter_parm[type].getscl);
  }
  
  static int parport_getsda(void *data)
  {
  	return line_get(&adapter_parm[type].getsda);
  }
  
  /* Encapsulate the functions above in the correct structure
     Note that getscl will be set to NULL by the attaching code for adapters
     that cannot read SCL back */
  static struct i2c_algo_bit_data parport_algo_data = {
  	.setsda		= parport_setsda,
  	.setscl		= parport_setscl,
  	.getsda		= parport_getsda,
  	.getscl		= parport_getscl,
  	.udelay		= 50,
  	.timeout	= HZ,
  };
  
  /* ----- Driver registration ---------------------------------------------- */
  
  static struct i2c_adapter parport_adapter = {
  	.owner		= THIS_MODULE,
  	.class		= I2C_CLASS_HWMON,
  	.algo_data	= &parport_algo_data,
  	.name		= "Parallel port adapter (light)",
  };
  
  /* SMBus alert support */
  static struct i2c_smbus_alert_setup alert_data = {
  	.alert_edge_triggered	= 1,
  };
  static struct i2c_client *ara;
  static struct lineop parport_ctrl_irq = {
  	.val		= (1 << 4),
  	.port		= PORT_CTRL,
  };
  
  static int i2c_parport_probe(struct platform_device *pdev)
  {
  	int err;
  
  	/* Reset hardware to a sane state (SCL and SDA high) */
  	parport_setsda(NULL, 1);
  	parport_setscl(NULL, 1);
  	/* Other init if needed (power on...) */
  	if (adapter_parm[type].init.val) {
  		line_set(1, &adapter_parm[type].init);
  		/* Give powered devices some time to settle */
  		msleep(100);
  	}
  
  	parport_adapter.dev.parent = &pdev->dev;
  	err = i2c_bit_add_bus(&parport_adapter);
  	if (err) {
  		dev_err(&pdev->dev, "Unable to register with I2C\n");
  		return err;
  	}
  
  	/* Setup SMBus alert if supported */
  	if (adapter_parm[type].smbus_alert && irq) {
  		alert_data.irq = irq;
  		ara = i2c_setup_smbus_alert(&parport_adapter, &alert_data);
  		if (ara)
  			line_set(1, &parport_ctrl_irq);
  		else
  			dev_warn(&pdev->dev, "Failed to register ARA client\n");
  	}
  
  	return 0;
  }
  
  static int i2c_parport_remove(struct platform_device *pdev)
  {
  	if (ara) {
  		line_set(0, &parport_ctrl_irq);
  		i2c_unregister_device(ara);
  		ara = NULL;
  	}
  	i2c_del_adapter(&parport_adapter);
  
  	/* Un-init if needed (power off...) */
  	if (adapter_parm[type].init.val)
  		line_set(0, &adapter_parm[type].init);
  
  	return 0;
  }
  
  static struct platform_driver i2c_parport_driver = {
  	.driver = {
  		.owner	= THIS_MODULE,
  		.name	= DRVNAME,
  	},
  	.probe		= i2c_parport_probe,
  	.remove		= i2c_parport_remove,
  };
  
  static int __init i2c_parport_device_add(u16 address)
  {
  	int err;
  
  	pdev = platform_device_alloc(DRVNAME, -1);
  	if (!pdev) {
  		err = -ENOMEM;
  		printk(KERN_ERR DRVNAME ": Device allocation failed\n");
  		goto exit;
  	}
  
  	err = platform_device_add(pdev);
  	if (err) {
  		printk(KERN_ERR DRVNAME ": Device addition failed (%d)\n",
  		       err);
  		goto exit_device_put;
  	}
  
  	return 0;
  
  exit_device_put:
  	platform_device_put(pdev);
  exit:
  	return err;
  }
  
  static int __init i2c_parport_init(void)
  {
  	int err;
  
  	if (type < 0) {
  		printk(KERN_ERR DRVNAME ": adapter type unspecified\n");
  		return -ENODEV;
  	}
  
  	if (type >= ARRAY_SIZE(adapter_parm)) {
  		printk(KERN_ERR DRVNAME ": invalid type (%d)\n", type);
  		return -ENODEV;
  	}
  
  	if (base == 0) {
  		pr_info(DRVNAME ": using default base 0x%x\n", DEFAULT_BASE);
  		base = DEFAULT_BASE;
  	}
  
  	if (!request_region(base, 3, DRVNAME))
  		return -EBUSY;
  
  	if (irq != 0)
  		pr_info(DRVNAME ": using irq %d\n", irq);
  
  	if (!adapter_parm[type].getscl.val)
  		parport_algo_data.getscl = NULL;
  
  	/* Sets global pdev as a side effect */
  	err = i2c_parport_device_add(base);
  	if (err)
  		goto exit_release;
  
  	err = platform_driver_register(&i2c_parport_driver);
  	if (err)
  		goto exit_device;
  
  	return 0;
  
  exit_device:
  	platform_device_unregister(pdev);
  exit_release:
  	release_region(base, 3);
  	return err;
  }
  
  static void __exit i2c_parport_exit(void)
  {
  	platform_driver_unregister(&i2c_parport_driver);
  	platform_device_unregister(pdev);
  	release_region(base, 3);
  }
  
  MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
  MODULE_DESCRIPTION("I2C bus over parallel port (light)");
  MODULE_LICENSE("GPL");
  
  module_init(i2c_parport_init);
  module_exit(i2c_parport_exit);
  