Date:	Thu, 18 Sep 2008 16:04:27 +0200
From:	"Hans J. Koch" <hjk@...utronix.de>
To:	John Ogness <john.ogness@...utronix.de>
Cc:	"Hans J. Koch" <hjk@...utronix.de>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCHv3 1/1] uio: add automata sercos3 pci card support

On Thu, Sep 18, 2008 at 11:57:15AM +0200, John Ogness wrote:
> Here is a new version of the patch to support the Automata Sercos III
> PCI card driver. I now check that the IRQ is enabled before accepting
> the interrupt.

Fine ;-)

> 
> I still use a logical OR to store the enabled interrupts and I've
> added a second use of a logical OR when restoring the enabled
> interrupts. I added an explanation of why I do this in comments at the
> top of the source file.

Good, thanks.

> 
> Since I use a logical OR, I also removed the extra checks if the
> Interrupt Enable Register and ier0_cache are 0.

Greg, could you please add this v3 of the patch to your tree?

John tested this on a VIA C3 with a test program causing 4000 irqs per
second, it works fine.

> 
> Signed-off-by: John Ogness <john.ogness@...utronix.de>

Signed-off-by: Hans J. Koch <hjk@...utronix.de>

> ---
>  drivers/uio/Kconfig       |   13 +
>  drivers/uio/Makefile      |    1 
>  drivers/uio/uio_sercos3.c |  243 ++++++++++++++++++++++++++++++++++++
>  3 files changed, 257 insertions(+)
> diff -uprN a/drivers/uio/Kconfig b/drivers/uio/Kconfig
> --- a/drivers/uio/Kconfig	2008-09-17 10:25:40.000000000 +0200
> +++ b/drivers/uio/Kconfig	2008-09-16 12:13:24.000000000 +0200
> @@ -58,4 +58,17 @@ config UIO_SMX
>  
>  	  If you compile this as a module, it will be called uio_smx.
>  
> +config UIO_SERCOS3
> +	tristate "Automata Sercos III PCI card driver"
> +	default n
> +	help
> +	  Userspace I/O interface for the Sercos III PCI card from
> +	  Automata GmbH. The userspace part of this driver will be
> +	  available for download from the Automata GmbH web site.
> +
> +	  Automata GmbH:        http://www.automataweb.com
> +	  Sercos III interface: http://www.sercos.com
> +
> +	  If you compile this as a module, it will be called uio_sercos3.
> +
>  endif
> diff -uprN a/drivers/uio/Makefile b/drivers/uio/Makefile
> --- a/drivers/uio/Makefile	2008-09-17 10:25:40.000000000 +0200
> +++ b/drivers/uio/Makefile	2008-09-15 15:20:21.000000000 +0200
> @@ -3,3 +3,4 @@ obj-$(CONFIG_UIO_CIF)	+= uio_cif.o
>  obj-$(CONFIG_UIO_PDRV)	+= uio_pdrv.o
>  obj-$(CONFIG_UIO_PDRV_GENIRQ)	+= uio_pdrv_genirq.o
>  obj-$(CONFIG_UIO_SMX)	+= uio_smx.o
> +obj-$(CONFIG_UIO_SERCOS3)	+= uio_sercos3.o
> diff -uprN a/drivers/uio/uio_sercos3.c b/drivers/uio/uio_sercos3.c
> --- a/drivers/uio/uio_sercos3.c	1970-01-01 01:00:00.000000000 +0100
> +++ b/drivers/uio/uio_sercos3.c	2008-09-18 11:49:34.000000000 +0200
> @@ -0,0 +1,243 @@
> +/* sercos3: UIO driver for the Automata Sercos III PCI card
> +
> +   Copyright (C) 2008 Linutronix GmbH
> +     Author: John Ogness <john.ogness@...utronix.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>
> +
> +/* 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_DISABLED | 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@...utronix.de>");
> +MODULE_LICENSE("GPL v2");
--
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