/* display7seg.c - Driver implementation for the 7-segment display
   *                 present on Sun Microsystems CP1400 and CP1500
   *
   * Copyright (c) 2000 Eric Brower (ebrower@usa.net)
   */
  
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/fs.h>
  #include <linux/errno.h>
  #include <linux/major.h>
  #include <linux/miscdevice.h>
  #include <linux/ioport.h>		/* request_region */
  #include <linux/slab.h>
  #include <linux/mutex.h>
  #include <linux/of.h>
  #include <linux/of_device.h>
  #include <linux/atomic.h>
  #include <asm/uaccess.h>		/* put_/get_user			*/
  #include <asm/io.h>
  
  #include <asm/display7seg.h>
  
  #define D7S_MINOR	193
  #define DRIVER_NAME	"d7s"
  #define PFX		DRIVER_NAME ": "
  
  static DEFINE_MUTEX(d7s_mutex);
  static int sol_compat = 0;		/* Solaris compatibility mode	*/
  
  /* Solaris compatibility flag -
   * The Solaris implementation omits support for several
   * documented driver features (ref Sun doc 806-0180-03).  
   * By default, this module supports the documented driver 
   * abilities, rather than the Solaris implementation:
   *
   * 	1) Device ALWAYS reverts to OBP-specified FLIPPED mode
   * 	   upon closure of device or module unload.
   * 	2) Device ioctls D7SIOCRD/D7SIOCWR honor toggling of
   * 	   FLIP bit
   *
   * If you wish the device to operate as under Solaris,
   * omitting above features, set this parameter to non-zero.
   */
  module_param(sol_compat, int, 0);
  MODULE_PARM_DESC(sol_compat, 
  		 "Disables documented functionality omitted from Solaris driver");
  
  MODULE_AUTHOR("Eric Brower <ebrower@usa.net>");
  MODULE_DESCRIPTION("7-Segment Display driver for Sun Microsystems CP1400/1500");
  MODULE_LICENSE("GPL");
  MODULE_SUPPORTED_DEVICE("d7s");
  
  struct d7s {
  	void __iomem	*regs;
  	bool		flipped;
  };
  struct d7s *d7s_device;
  
  /*
   * Register block address- see header for details
   * -----------------------------------------
   * | DP | ALARM | FLIP | 4 | 3 | 2 | 1 | 0 |
   * -----------------------------------------
   *
   * DP 		- Toggles decimal point on/off 
   * ALARM	- Toggles "Alarm" LED green/red
   * FLIP		- Inverts display for upside-down mounted board
   * bits 0-4	- 7-segment display contents
   */
  static atomic_t d7s_users = ATOMIC_INIT(0);
  
  static int d7s_open(struct inode *inode, struct file *f)
  {
  	if (D7S_MINOR != iminor(inode))
  		return -ENODEV;
  	atomic_inc(&d7s_users);
  	return 0;
  }
  
  static int d7s_release(struct inode *inode, struct file *f)
  {
  	/* Reset flipped state to OBP default only if
  	 * no other users have the device open and we
  	 * are not operating in solaris-compat mode
  	 */
  	if (atomic_dec_and_test(&d7s_users) && !sol_compat) {
  		struct d7s *p = d7s_device;
  		u8 regval = 0;
  
  		regval = readb(p->regs);
  		if (p->flipped)
  			regval |= D7S_FLIP;
  		else
  			regval &= ~D7S_FLIP;
  		writeb(regval, p->regs);
  	}
  
  	return 0;
  }
  
  static long d7s_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
  {
  	struct d7s *p = d7s_device;
  	u8 regs = readb(p->regs);
  	int error = 0;
  	u8 ireg = 0;
  
  	if (D7S_MINOR != iminor(file_inode(file)))
  		return -ENODEV;
  
  	mutex_lock(&d7s_mutex);
  	switch (cmd) {
  	case D7SIOCWR:
  		/* assign device register values we mask-out D7S_FLIP
  		 * if in sol_compat mode
  		 */
  		if (get_user(ireg, (int __user *) arg)) {
  			error = -EFAULT;
  			break;
  		}
  		if (sol_compat) {
  			if (regs & D7S_FLIP)
  				ireg |= D7S_FLIP;
  			else
  				ireg &= ~D7S_FLIP;
  		}
  		writeb(ireg, p->regs);
  		break;
  
  	case D7SIOCRD:
  		/* retrieve device register values
  		 * NOTE: Solaris implementation returns D7S_FLIP bit
  		 * as toggled by user, even though it does not honor it.
  		 * This driver will not misinform you about the state
  		 * of your hardware while in sol_compat mode
  		 */
  		if (put_user(regs, (int __user *) arg)) {
  			error = -EFAULT;
  			break;
  		}
  		break;
  
  	case D7SIOCTM:
  		/* toggle device mode-- flip display orientation */
  		if (regs & D7S_FLIP)
  			regs &= ~D7S_FLIP;
  		else
  			regs |= D7S_FLIP;
  		writeb(regs, p->regs);
  		break;
  	}
  	mutex_unlock(&d7s_mutex);
  
  	return error;
  }
  
  static const struct file_operations d7s_fops = {
  	.owner =		THIS_MODULE,
  	.unlocked_ioctl =	d7s_ioctl,
  	.compat_ioctl =		d7s_ioctl,
  	.open =			d7s_open,
  	.release =		d7s_release,
  	.llseek = noop_llseek,
  };
  
  static struct miscdevice d7s_miscdev = {
  	.minor		= D7S_MINOR,
  	.name		= DRIVER_NAME,
  	.fops		= &d7s_fops
  };
  
  static int d7s_probe(struct platform_device *op)
  {
  	struct device_node *opts;
  	int err = -EINVAL;
  	struct d7s *p;
  	u8 regs;
  
  	if (d7s_device)
  		goto out;
  
  	p = kzalloc(sizeof(*p), GFP_KERNEL);
  	err = -ENOMEM;
  	if (!p)
  		goto out;
  
  	p->regs = of_ioremap(&op->resource[0], 0, sizeof(u8), "d7s");
  	if (!p->regs) {
  		printk(KERN_ERR PFX "Cannot map chip registers
  ");
  		goto out_free;
  	}
  
  	err = misc_register(&d7s_miscdev);
  	if (err) {
  		printk(KERN_ERR PFX "Unable to acquire miscdevice minor %i
  ",
  		       D7S_MINOR);
  		goto out_iounmap;
  	}
  
  	/* OBP option "d7s-flipped?" is honored as default for the
  	 * device, and reset default when detached
  	 */
  	regs = readb(p->regs);
  	opts = of_find_node_by_path("/options");
  	if (opts &&
  	    of_get_property(opts, "d7s-flipped?", NULL))
  		p->flipped = true;
  
  	if (p->flipped)
  		regs |= D7S_FLIP;
  	else
  		regs &= ~D7S_FLIP;
  
  	writeb(regs,  p->regs);
  
  	printk(KERN_INFO PFX "7-Segment Display%s at [%s:0x%llx] %s
  ",
  	       op->dev.of_node->full_name,
  	       (regs & D7S_FLIP) ? " (FLIPPED)" : "",
  	       op->resource[0].start,
  	       sol_compat ? "in sol_compat mode" : "");
  
  	dev_set_drvdata(&op->dev, p);
  	d7s_device = p;
  	err = 0;
  
  out:
  	return err;
  
  out_iounmap:
  	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
  
  out_free:
  	kfree(p);
  	goto out;
  }
  
  static int d7s_remove(struct platform_device *op)
  {
  	struct d7s *p = dev_get_drvdata(&op->dev);
  	u8 regs = readb(p->regs);
  
  	/* Honor OBP d7s-flipped? unless operating in solaris-compat mode */
  	if (sol_compat) {
  		if (p->flipped)
  			regs |= D7S_FLIP;
  		else
  			regs &= ~D7S_FLIP;
  		writeb(regs, p->regs);
  	}
  
  	misc_deregister(&d7s_miscdev);
  	of_iounmap(&op->resource[0], p->regs, sizeof(u8));
  	kfree(p);
  
  	return 0;
  }
  
  static const struct of_device_id d7s_match[] = {
  	{
  		.name = "display7seg",
  	},
  	{},
  };
  MODULE_DEVICE_TABLE(of, d7s_match);
  
  static struct platform_driver d7s_driver = {
  	.driver = {
  		.name = DRIVER_NAME,
  		.owner = THIS_MODULE,
  		.of_match_table = d7s_match,
  	},
  	.probe		= d7s_probe,
  	.remove		= d7s_remove,
  };
  
  module_platform_driver(d7s_driver);