drivers/uio/uio_sercos3.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* sercos3: UIO driver for the Automata Sercos III PCI card
   3
   4    Copyright (C) 2008 Linutronix GmbH
   5      Author: John Ogness <john.ogness@linutronix.de>
   6
   7    This is a straight-forward UIO driver, where interrupts are disabled
   8    by the interrupt handler and re-enabled via a write to the UIO device
   9    by the userspace-part.
  10
  11    The only part that may seem odd is the use of a logical OR when
  12    storing and restoring enabled interrupts. This is done because the
  13    userspace-part could directly modify the Interrupt Enable Register
  14    at any time. To reduce possible conflicts, the kernel driver uses
  15    a logical OR to make more controlled changes (rather than blindly
  16    overwriting previous values).
  17
  18    Race conditions exist if the userspace-part directly modifies the
  19    Interrupt Enable Register while in operation. The consequences are
  20    that certain interrupts would fail to be enabled or disabled. For
  21    this reason, the userspace-part should only directly modify the
  22    Interrupt Enable Register at the beginning (to get things going).
  23    The userspace-part can safely disable interrupts at any time using
  24    a write to the UIO device.
  25 */
  26
  27 #include <linux/device.h>
  28 #include <linux/module.h>
  29 #include <linux/pci.h>
  30 #include <linux/uio_driver.h>
  31 #include <linux/io.h>
  32 #include <linux/slab.h>
  33
  34 /* ID's for SERCOS III PCI card (PLX 9030) */
  35 #define SERCOS_SUB_VENDOR_ID  0x1971
  36 #define SERCOS_SUB_SYSID_3530 0x3530
  37 #define SERCOS_SUB_SYSID_3535 0x3535
  38 #define SERCOS_SUB_SYSID_3780 0x3780
  39
  40 /* Interrupt Enable Register */
  41 #define IER0_OFFSET 0x08
  42
  43 /* Interrupt Status Register */
  44 #define ISR0_OFFSET 0x18
  45
  46 struct sercos3_priv {
  47         u32 ier0_cache;
  48         spinlock_t ier0_cache_lock;
  49 };
  50
  51 /* this function assumes ier0_cache_lock is locked! */
  52 static void sercos3_disable_interrupts(struct uio_info *info,
  53                                        struct sercos3_priv *priv)
  54 {
  55         void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  56
  57         /* add enabled interrupts to cache */
  58         priv->ier0_cache |= ioread32(ier0);
  59
  60         /* disable interrupts */
  61         iowrite32(0, ier0);
  62 }
  63
  64 /* this function assumes ier0_cache_lock is locked! */
  65 static void sercos3_enable_interrupts(struct uio_info *info,
  66                                       struct sercos3_priv *priv)
  67 {
  68         void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  69
  70         /* restore previously enabled interrupts */
  71         iowrite32(ioread32(ier0) | priv->ier0_cache, ier0);
  72         priv->ier0_cache = 0;
  73 }
  74
  75 static irqreturn_t sercos3_handler(int irq, struct uio_info *info)
  76 {
  77         struct sercos3_priv *priv = info->priv;
  78         void __iomem *isr0 = info->mem[3].internal_addr + ISR0_OFFSET;
  79         void __iomem *ier0 = info->mem[3].internal_addr + IER0_OFFSET;
  80
  81         if (!(ioread32(isr0) & ioread32(ier0)))
  82                 return IRQ_NONE;
  83
  84         spin_lock(&priv->ier0_cache_lock);
  85         sercos3_disable_interrupts(info, priv);
  86         spin_unlock(&priv->ier0_cache_lock);
  87
  88         return IRQ_HANDLED;
  89 }
  90
  91 static int sercos3_irqcontrol(struct uio_info *info, s32 irq_on)
  92 {
  93         struct sercos3_priv *priv = info->priv;
  94
  95         spin_lock_irq(&priv->ier0_cache_lock);
  96         if (irq_on)
  97                 sercos3_enable_interrupts(info, priv);
  98         else
  99                 sercos3_disable_interrupts(info, priv);
 100         spin_unlock_irq(&priv->ier0_cache_lock);
 101
 102         return 0;
 103 }
 104
 105 static int sercos3_setup_iomem(struct pci_dev *dev, struct uio_info *info,
 106                                int n, int pci_bar)
 107 {
 108         info->mem[n].addr = pci_resource_start(dev, pci_bar);
 109         if (!info->mem[n].addr)
 110                 return -1;
 111         info->mem[n].internal_addr = ioremap(pci_resource_start(dev, pci_bar),
 112                                              pci_resource_len(dev, pci_bar));
 113         if (!info->mem[n].internal_addr)
 114                 return -1;
 115         info->mem[n].size = pci_resource_len(dev, pci_bar);
 116         info->mem[n].memtype = UIO_MEM_PHYS;
 117         return 0;
 118 }
 119
 120 static int sercos3_pci_probe(struct pci_dev *dev,
 121                                        const struct pci_device_id *id)
 122 {
 123         struct uio_info *info;
 124         struct sercos3_priv *priv;
 125         int i;
 126
 127         info = devm_kzalloc(&dev->dev, sizeof(struct uio_info), GFP_KERNEL);
 128         if (!info)
 129                 return -ENOMEM;
 130
 131         priv = devm_kzalloc(&dev->dev, sizeof(struct sercos3_priv), GFP_KERNEL);
 132         if (!priv)
 133                 return -ENOMEM;
 134
 135         if (pci_enable_device(dev))
 136                 return -ENODEV;
 137
 138         if (pci_request_regions(dev, "sercos3"))
 139                 goto out_disable;
 140
 141         /* we only need PCI BAR's 0, 2, 3, 4, 5 */
 142         if (sercos3_setup_iomem(dev, info, 0, 0))
 143                 goto out_unmap;
 144         if (sercos3_setup_iomem(dev, info, 1, 2))
 145                 goto out_unmap;
 146         if (sercos3_setup_iomem(dev, info, 2, 3))
 147                 goto out_unmap;
 148         if (sercos3_setup_iomem(dev, info, 3, 4))
 149                 goto out_unmap;
 150         if (sercos3_setup_iomem(dev, info, 4, 5))
 151                 goto out_unmap;
 152
 153         spin_lock_init(&priv->ier0_cache_lock);
 154         info->priv = priv;
 155         info->name = "Sercos_III_PCI";
 156         info->version = "0.0.1";
 157         info->irq = dev->irq;
 158         info->irq_flags = IRQF_SHARED;
 159         info->handler = sercos3_handler;
 160         info->irqcontrol = sercos3_irqcontrol;
 161
 162         pci_set_drvdata(dev, info);
 163
 164         if (uio_register_device(&dev->dev, info))
 165                 goto out_unmap;
 166
 167         return 0;
 168
 169 out_unmap:
 170         for (i = 0; i < 5; i++) {
 171                 if (info->mem[i].internal_addr)
 172                         iounmap(info->mem[i].internal_addr);
 173         }
 174         pci_release_regions(dev);
 175 out_disable:
 176         pci_disable_device(dev);
 177         return -ENODEV;
 178 }
 179
 180 static void sercos3_pci_remove(struct pci_dev *dev)
 181 {
 182         struct uio_info *info = pci_get_drvdata(dev);
 183         int i;
 184
 185         uio_unregister_device(info);
 186         pci_release_regions(dev);
 187         pci_disable_device(dev);
 188         for (i = 0; i < 5; i++) {
 189                 if (info->mem[i].internal_addr)
 190                         iounmap(info->mem[i].internal_addr);
 191         }
 192 }
 193
 194 static struct pci_device_id sercos3_pci_ids[] = {
 195         {
 196                 .vendor =       PCI_VENDOR_ID_PLX,
 197                 .device =       PCI_DEVICE_ID_PLX_9030,
 198                 .subvendor =    SERCOS_SUB_VENDOR_ID,
 199                 .subdevice =    SERCOS_SUB_SYSID_3530,
 200         },
 201         {
 202                 .vendor =       PCI_VENDOR_ID_PLX,
 203                 .device =       PCI_DEVICE_ID_PLX_9030,
 204                 .subvendor =    SERCOS_SUB_VENDOR_ID,
 205                 .subdevice =    SERCOS_SUB_SYSID_3535,
 206         },
 207         {
 208                 .vendor =       PCI_VENDOR_ID_PLX,
 209                 .device =       PCI_DEVICE_ID_PLX_9030,
 210                 .subvendor =    SERCOS_SUB_VENDOR_ID,
 211                 .subdevice =    SERCOS_SUB_SYSID_3780,
 212         },
 213         { 0, }
 214 };
 215
 216 static struct pci_driver sercos3_pci_driver = {
 217         .name = "sercos3",
 218         .id_table = sercos3_pci_ids,
 219         .probe = sercos3_pci_probe,
 220         .remove = sercos3_pci_remove,
 221 };
 222
 223 module_pci_driver(sercos3_pci_driver);
 224 MODULE_DESCRIPTION("UIO driver for the Automata Sercos III PCI card");
 225 MODULE_AUTHOR("John Ogness <john.ogness@linutronix.de>");
 226 MODULE_LICENSE("GPL v2");