/* sercos3: UIO driver for the Automata Sercos III PCI card
  
     Copyright (C) 2008 Linutronix GmbH
       Author: John Ogness <john.ogness@linutronix.de>
  
     This is a straight-forward UIO driver, where interrupts are disabled
     by the interrupt handler and re-enabled via a write to the UIO device
     by the userspace-part.
  
     The only part that may seem odd is the use of a logical OR when
     storing and restoring enabled interrupts. This is done because the
     userspace-part could directly modify the Interrupt Enable Register
     at any time. To reduce possible conflicts, the kernel driver uses
     a logical OR to make more controlled changes (rather than blindly
     overwriting previous values).
  
     Race conditions exist if the userspace-part directly modifies the
     Interrupt Enable Register while in operation. The consequences are
     that certain interrupts would fail to be enabled or disabled. For
     this reason, the userspace-part should only directly modify the
     Interrupt Enable Register at the beginning (to get things going).
     The userspace-part can safely disable interrupts at any time using
     a write to the UIO device.
  */
  
  #include <linux/device.h>
  #include <linux/module.h>
  #include <linux/pci.h>
  #include <linux/uio_driver.h>
  #include <linux/io.h>

  #include <linux/slab.h>

  
  /* ID's for SERCOS III PCI card (PLX 9030) */
  #define SERCOS_SUB_VENDOR_ID  0x1971
  #define SERCOS_SUB_SYSID_3530 0x3530
  #define SERCOS_SUB_SYSID_3535 0x3535
  #define SERCOS_SUB_SYSID_3780 0x3780
  
  /* Interrupt Enable Register */
  #define IER0_OFFSET 0x08
  
  /* Interrupt Status Register */
  #define ISR0_OFFSET 0x18
  
  struct sercos3_priv {
  	u32 ier0_cache;
  	spinlock_t ier0_cache_lock;
  };
  
  /* this function assumes ier0_cache_lock is locked! */
  static void sercos3_disable_interrupts(struct uio_info *info,
  				       struct sercos3_priv *priv)
  {
  	void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  
  	/* add enabled interrupts to cache */
  	priv->ier0_cache |= ioread32(ier0);
  
  	/* disable interrupts */
  	iowrite32(0, ier0);
  }
  
  /* this function assumes ier0_cache_lock is locked! */
  static void sercos3_enable_interrupts(struct uio_info *info,
  				      struct sercos3_priv *priv)
  {
  	void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  
  	/* restore previously enabled interrupts */
  	iowrite32(ioread32(ier0) | priv->ier0_cache, ier0);
  	priv->ier0_cache = 0;
  }
  
  static irqreturn_t sercos3_handler(int irq, struct uio_info *info)
  {
  	struct sercos3_priv *priv = info->priv;
  	void __iomem *isr0 = info->mem[3].internal_addr + ISR0_OFFSET;
  	void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  
  	if (!(ioread32(isr0) & ioread32(ier0)))
  		return IRQ_NONE;
  
  	spin_lock(&priv->ier0_cache_lock);
  	sercos3_disable_interrupts(info, priv);
  	spin_unlock(&priv->ier0_cache_lock);
  
  	return IRQ_HANDLED;
  }
  
  static int sercos3_irqcontrol(struct uio_info *info, s32 irq_on)
  {
  	struct sercos3_priv *priv = info->priv;
  
  	spin_lock_irq(&priv->ier0_cache_lock);
  	if (irq_on)
  		sercos3_enable_interrupts(info, priv);
  	else
  		sercos3_disable_interrupts(info, priv);
  	spin_unlock_irq(&priv->ier0_cache_lock);
  
  	return 0;
  }
  
  static int sercos3_setup_iomem(struct pci_dev *dev, struct uio_info *info,
  			       int n, int pci_bar)
  {
  	info->mem[n].addr = pci_resource_start(dev, pci_bar);
  	if (!info->mem[n].addr)
  		return -1;
  	info->mem[n].internal_addr = ioremap(pci_resource_start(dev, pci_bar),
  					     pci_resource_len(dev, pci_bar));
  	if (!info->mem[n].internal_addr)
  		return -1;
  	info->mem[n].size = pci_resource_len(dev, pci_bar);
  	info->mem[n].memtype = UIO_MEM_PHYS;
  	return 0;
  }
  
  static int __devinit sercos3_pci_probe(struct pci_dev *dev,
  				       const struct pci_device_id *id)
  {
  	struct uio_info *info;
  	struct sercos3_priv *priv;
  	int i;
  
  	info = kzalloc(sizeof(struct uio_info), GFP_KERNEL);
  	if (!info)
  		return -ENOMEM;
  
  	priv = kzalloc(sizeof(struct sercos3_priv), GFP_KERNEL);
  	if (!priv)
  		goto out_free;
  
  	if (pci_enable_device(dev))
  		goto out_free_priv;
  
  	if (pci_request_regions(dev, "sercos3"))
  		goto out_disable;
  
  	/* we only need PCI BAR's 0, 2, 3, 4, 5 */
  	if (sercos3_setup_iomem(dev, info, 0, 0))
  		goto out_unmap;
  	if (sercos3_setup_iomem(dev, info, 1, 2))
  		goto out_unmap;
  	if (sercos3_setup_iomem(dev, info, 2, 3))
  		goto out_unmap;
  	if (sercos3_setup_iomem(dev, info, 3, 4))
  		goto out_unmap;
  	if (sercos3_setup_iomem(dev, info, 4, 5))
  		goto out_unmap;
  
  	spin_lock_init(&priv->ier0_cache_lock);
  	info->priv = priv;
  	info->name = "Sercos_III_PCI";
  	info->version = "0.0.1";
  	info->irq = dev->irq;

  	info->irq_flags = IRQF_SHARED;

  	info->handler = sercos3_handler;
  	info->irqcontrol = sercos3_irqcontrol;
  
  	pci_set_drvdata(dev, info);
  
  	if (uio_register_device(&dev->dev, info))
  		goto out_unmap;
  
  	return 0;
  
  out_unmap:
  	for (i = 0; i < 5; i++) {
  		if (info->mem[i].internal_addr)
  			iounmap(info->mem[i].internal_addr);
  	}
  	pci_release_regions(dev);
  out_disable:
  	pci_disable_device(dev);
  out_free_priv:
  	kfree(priv);
  out_free:
  	kfree(info);
  	return -ENODEV;
  }
  
  static void sercos3_pci_remove(struct pci_dev *dev)
  {
  	struct uio_info *info = pci_get_drvdata(dev);
  	int i;
  
  	uio_unregister_device(info);
  	pci_release_regions(dev);
  	pci_disable_device(dev);
  	pci_set_drvdata(dev, NULL);
  	for (i = 0; i < 5; i++) {
  		if (info->mem[i].internal_addr)
  			iounmap(info->mem[i].internal_addr);
  	}
  	kfree(info->priv);
  	kfree(info);
  }
  
  static struct pci_device_id sercos3_pci_ids[] __devinitdata = {
  	{
  		.vendor =       PCI_VENDOR_ID_PLX,
  		.device =       PCI_DEVICE_ID_PLX_9030,
  		.subvendor =    SERCOS_SUB_VENDOR_ID,
  		.subdevice =    SERCOS_SUB_SYSID_3530,
  	},
  	{
  		.vendor =       PCI_VENDOR_ID_PLX,
  		.device =       PCI_DEVICE_ID_PLX_9030,
  		.subvendor =    SERCOS_SUB_VENDOR_ID,
  		.subdevice =    SERCOS_SUB_SYSID_3535,
  	},
  	{
  		.vendor =       PCI_VENDOR_ID_PLX,
  		.device =       PCI_DEVICE_ID_PLX_9030,
  		.subvendor =    SERCOS_SUB_VENDOR_ID,
  		.subdevice =    SERCOS_SUB_SYSID_3780,
  	},
  	{ 0, }
  };
  
  static struct pci_driver sercos3_pci_driver = {
  	.name = "sercos3",
  	.id_table = sercos3_pci_ids,
  	.probe = sercos3_pci_probe,
  	.remove = sercos3_pci_remove,
  };
  
  static int __init sercos3_init_module(void)
  {
  	return pci_register_driver(&sercos3_pci_driver);
  }
  
  static void __exit sercos3_exit_module(void)
  {
  	pci_unregister_driver(&sercos3_pci_driver);
  }
  
  module_init(sercos3_init_module);
  module_exit(sercos3_exit_module);
  
  MODULE_DESCRIPTION("UIO driver for the Automata Sercos III PCI card");
  MODULE_AUTHOR("John Ogness <john.ogness@linutronix.de>");
  MODULE_LICENSE("GPL v2");