drivers/uio/uio_sercos3.c

   1 /* sercos3: UIO driver for the Automata Sercos III PCI card
   2
   3    Copyright (C) 2008 Linutronix GmbH
   4      Author: John Ogness <john.ogness@linutronix.de>
   5
   6    This is a straight-forward UIO driver, where interrupts are disabled
   7    by the interrupt handler and re-enabled via a write to the UIO device
   8    by the userspace-part.
   9
  10    The only part that may seem odd is the use of a logical OR when
  11    storing and restoring enabled interrupts. This is done because the
  12    userspace-part could directly modify the Interrupt Enable Register
  13    at any time. To reduce possible conflicts, the kernel driver uses
  14    a logical OR to make more controlled changes (rather than blindly
  15    overwriting previous values).
  16
  17    Race conditions exist if the userspace-part directly modifies the
  18    Interrupt Enable Register while in operation. The consequences are
  19    that certain interrupts would fail to be enabled or disabled. For
  20    this reason, the userspace-part should only directly modify the
  21    Interrupt Enable Register at the beginning (to get things going).
  22    The userspace-part can safely disable interrupts at any time using
  23    a write to the UIO device.
  24 */
  25
  26 #include <linux/device.h>
  27 #include <linux/module.h>
  28 #include <linux/pci.h>
  29 #include <linux/uio_driver.h>
  30 #include <linux/io.h>
  31 #include <linux/slab.h>
  32
  33 /* ID's for SERCOS III PCI card (PLX 9030) */
  34 #define SERCOS_SUB_VENDOR_ID  0x1971
  35 #define SERCOS_SUB_SYSID_3530 0x3530
  36 #define SERCOS_SUB_SYSID_3535 0x3535
  37 #define SERCOS_SUB_SYSID_3780 0x3780
  38
  39 /* Interrupt Enable Register */
  40 #define IER0_OFFSET 0x08
  41
  42 /* Interrupt Status Register */
  43 #define ISR0_OFFSET 0x18
  44
  45 struct sercos3_priv {
  46         u32 ier0_cache;
  47         spinlock_t ier0_cache_lock;
  48 };
  49
  50 /* this function assumes ier0_cache_lock is locked! */
  51 static void sercos3_disable_interrupts(struct uio_info *info,
  52                                        struct sercos3_priv *priv)
  53 {
  54         void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  55
  56         /* add enabled interrupts to cache */
  57         priv->ier0_cache |= ioread32(ier0);
  58
  59         /* disable interrupts */
  60         iowrite32(0, ier0);
  61 }
  62
  63 /* this function assumes ier0_cache_lock is locked! */
  64 static void sercos3_enable_interrupts(struct uio_info *info,
  65                                       struct sercos3_priv *priv)
  66 {
  67         void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  68
  69         /* restore previously enabled interrupts */
  70         iowrite32(ioread32(ier0) | priv->ier0_cache, ier0);
  71         priv->ier0_cache = 0;
  72 }
  73
  74 static irqreturn_t sercos3_handler(int irq, struct uio_info *info)
  75 {
  76         struct sercos3_priv *priv = info->priv;
  77         void __iomem *isr0 = info->mem[3].internal_addr + ISR0_OFFSET;
  78         void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  79
  80         if (!(ioread32(isr0) & ioread32(ier0)))
  81                 return IRQ_NONE;
  82
  83         spin_lock(&priv->ier0_cache_lock);
  84         sercos3_disable_interrupts(info, priv);
  85         spin_unlock(&priv->ier0_cache_lock);
  86
  87         return IRQ_HANDLED;
  88 }
  89
  90 static int sercos3_irqcontrol(struct uio_info *info, s32 irq_on)
  91 {
  92         struct sercos3_priv *priv = info->priv;
  93
  94         spin_lock_irq(&priv->ier0_cache_lock);
  95         if (irq_on)
  96                 sercos3_enable_interrupts(info, priv);
  97         else
  98                 sercos3_disable_interrupts(info, priv);
  99         spin_unlock_irq(&priv->ier0_cache_lock);
 100
 101         return 0;
 102 }
 103
 104 static int sercos3_setup_iomem(struct pci_dev *dev, struct uio_info *info,
 105                                int n, int pci_bar)
 106 {
 107         info->mem[n].addr = pci_resource_start(dev, pci_bar);
 108         if (!info->mem[n].addr)
 109                 return -1;
 110         info->mem[n].internal_addr = ioremap(pci_resource_start(dev, pci_bar),
 111                                              pci_resource_len(dev, pci_bar));
 112         if (!info->mem[n].internal_addr)
 113                 return -1;
 114         info->mem[n].size = pci_resource_len(dev, pci_bar);
 115         info->mem[n].memtype = UIO_MEM_PHYS;
 116         return 0;
 117 }
 118
 119 static int sercos3_pci_probe(struct pci_dev *dev,
 120                                        const struct pci_device_id *id)
 121 {
 122         struct uio_info *info;
 123         struct sercos3_priv *priv;
 124         int i;
 125
 126         info = kzalloc(sizeof(struct uio_info), GFP_KERNEL);
 127         if (!info)
 128                 return -ENOMEM;
 129
 130         priv = kzalloc(sizeof(struct sercos3_priv), GFP_KERNEL);
 131         if (!priv)
 132                 goto out_free;
 133
 134         if (pci_enable_device(dev))
 135                 goto out_free_priv;
 136
 137         if (pci_request_regions(dev, "sercos3"))
 138                 goto out_disable;
 139
 140         /* we only need PCI BAR's 0, 2, 3, 4, 5 */
 141         if (sercos3_setup_iomem(dev, info, 0, 0))
 142                 goto out_unmap;
 143         if (sercos3_setup_iomem(dev, info, 1, 2))
 144                 goto out_unmap;
 145         if (sercos3_setup_iomem(dev, info, 2, 3))
 146                 goto out_unmap;
 147         if (sercos3_setup_iomem(dev, info, 3, 4))
 148                 goto out_unmap;
 149         if (sercos3_setup_iomem(dev, info, 4, 5))
 150                 goto out_unmap;
 151
 152         spin_lock_init(&priv->ier0_cache_lock);
 153         info->priv = priv;
 154         info->name = "Sercos_III_PCI";
 155         info->version = "0.0.1";
 156         info->irq = dev->irq;
 157         info->irq_flags = IRQF_SHARED;
 158         info->handler = sercos3_handler;
 159         info->irqcontrol = sercos3_irqcontrol;
 160
 161         pci_set_drvdata(dev, info);
 162
 163         if (uio_register_device(&dev->dev, info))
 164                 goto out_unmap;
 165
 166         return 0;
 167
 168 out_unmap:
 169         for (i = 0; i < 5; i++) {
 170                 if (info->mem[i].internal_addr)
 171                         iounmap(info->mem[i].internal_addr);
 172         }
 173         pci_release_regions(dev);
 174 out_disable:
 175         pci_disable_device(dev);
 176 out_free_priv:
 177         kfree(priv);
 178 out_free:
 179         kfree(info);
 180         return -ENODEV;
 181 }
 182
 183 static void sercos3_pci_remove(struct pci_dev *dev)
 184 {
 185         struct uio_info *info = pci_get_drvdata(dev);
 186         int i;
 187
 188         uio_unregister_device(info);
 189         pci_release_regions(dev);
 190         pci_disable_device(dev);
 191         for (i = 0; i < 5; i++) {
 192                 if (info->mem[i].internal_addr)
 193                         iounmap(info->mem[i].internal_addr);
 194         }
 195         kfree(info->priv);
 196         kfree(info);
 197 }
 198
 199 static struct pci_device_id sercos3_pci_ids[] = {
 200         {
 201                 .vendor =       PCI_VENDOR_ID_PLX,
 202                 .device =       PCI_DEVICE_ID_PLX_9030,
 203                 .subvendor =    SERCOS_SUB_VENDOR_ID,
 204                 .subdevice =    SERCOS_SUB_SYSID_3530,
 205         },
 206         {
 207                 .vendor =       PCI_VENDOR_ID_PLX,
 208                 .device =       PCI_DEVICE_ID_PLX_9030,
 209                 .subvendor =    SERCOS_SUB_VENDOR_ID,
 210                 .subdevice =    SERCOS_SUB_SYSID_3535,
 211         },
 212         {
 213                 .vendor =       PCI_VENDOR_ID_PLX,
 214                 .device =       PCI_DEVICE_ID_PLX_9030,
 215                 .subvendor =    SERCOS_SUB_VENDOR_ID,
 216                 .subdevice =    SERCOS_SUB_SYSID_3780,
 217         },
 218         { 0, }
 219 };
 220
 221 static struct pci_driver sercos3_pci_driver = {
 222         .name = "sercos3",
 223         .id_table = sercos3_pci_ids,
 224         .probe = sercos3_pci_probe,
 225         .remove = sercos3_pci_remove,
 226 };
 227
 228 module_pci_driver(sercos3_pci_driver);
 229 MODULE_DESCRIPTION("UIO driver for the Automata Sercos III PCI card");
 230 MODULE_AUTHOR("John Ogness <john.ogness@linutronix.de>");
 231 MODULE_LICENSE("GPL v2");