uio_sercos3.c
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/* 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 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);
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[] = {
{
.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,
};
module_pci_driver(sercos3_pci_driver);
MODULE_DESCRIPTION("UIO driver for the Automata Sercos III PCI card");
MODULE_AUTHOR("John Ogness <john.ogness@linutronix.de>");
MODULE_LICENSE("GPL v2");