linux/drivers/uio/uio_sercos3.c

// SPDX-License-Identifier: GPL-2.0
/* sercos3: UIO driver for the Automata Sercos III PCI card

   Copyright (C) 2008 Linutronix GmbH
     Author: John Ogness <[email protected]>

   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 …
#define SERCOS_SUB_SYSID_3530 …
#define SERCOS_SUB_SYSID_3535 …
#define SERCOS_SUB_SYSID_3780 …

/* Interrupt Enable Register */
#define IER0_OFFSET …

/* Interrupt Status Register */
#define ISR0_OFFSET …

struct sercos3_priv { … };

/* this function assumes ier0_cache_lock is locked! */
static void sercos3_disable_interrupts(struct uio_info *info,
				       struct sercos3_priv *priv)
{ … }

/* this function assumes ier0_cache_lock is locked! */
static void sercos3_enable_interrupts(struct uio_info *info,
				      struct sercos3_priv *priv)
{ … }

static irqreturn_t sercos3_handler(int irq, struct uio_info *info)
{ … }

static int sercos3_irqcontrol(struct uio_info *info, s32 irq_on)
{ … }

static int sercos3_setup_iomem(struct pci_dev *dev, struct uio_info *info,
			       int n, int pci_bar)
{ … }

static int sercos3_pci_probe(struct pci_dev *dev,
				       const struct pci_device_id *id)
{ … }

static void sercos3_pci_remove(struct pci_dev *dev)
{ … }

static struct pci_device_id sercos3_pci_ids[] = …;

static struct pci_driver sercos3_pci_driver = …;

module_pci_driver(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_AUTHOR(…) …;
MODULE_LICENSE(…) …;