Re: [v2 PATCH 1/2] Add new uio device for dynamic memory allocation

[Hans J. Koch]

On Tue, Sep 25, 2012 at 03:09:11PM +0900, Damian Hobson-Garcia wrote:
> This device extends the uio_pdrv_genirq driver to provide limited
> dynamic memory allocation for UIO devices.  This allows UIO devices
> to use CMA and IOMMU allocated memory regions. This driver is based
> on the uio_pdrv_genirq driver and provides the same generic interrupt
> handling capabilities.  Like uio_prdv_genirq,
> a fixed number of memory regions, defined in the platform device's
> .resources field are exported to userpace. This driver adds the ability
> to export additional regions whose number and size are known at boot time,
> but whose memory is not allocated until the uio device file is opened for
> the first time.  When the device file is closed, the allocated memory block
> is freed.  Physical (DMA) addresses for the dynamic regions are provided to
> the userspace via /sys/class/uio/uioX/maps/mapY/addr in the same way as
> static addresses are when the uio device file is open, when no processes
> are holding the device file open, the address returned to userspace is
> DMA_ERROR_CODE.
> 
> Signed-off-by: Damian Hobson-Garcia <dhobsong@xxxxxxxxxx>

Thanks for your contribution!

Signed-off-by: "Hans J. Koch" <hjk@xxxxxxxxxxxx>

> ---
>  drivers/uio/Kconfig                           |   16 ++
>  drivers/uio/Makefile                          |    1 +
>  drivers/uio/uio_dmem_genirq.c                 |  354 +++++++++++++++++++++++++
>  include/linux/platform_data/uio_dmem_genirq.h |   26 ++
>  4 files changed, 397 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/uio/uio_dmem_genirq.c
>  create mode 100644 include/linux/platform_data/uio_dmem_genirq.h
> 
> diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
> index 6f3ea9b..82e2b89 100644
> --- a/drivers/uio/Kconfig
> +++ b/drivers/uio/Kconfig
> @@ -44,6 +44,22 @@ config UIO_PDRV_GENIRQ
>  
>  	  If you don't know what to do here, say N.
>  
> +config UIO_DMEM_GENIRQ
> +	tristate "Userspace platform driver with generic irq and dynamic memory"
> +	help
> +	  Platform driver for Userspace I/O devices, including generic
> +	  interrupt handling code. Shared interrupts are not supported.
> +
> +	  Memory regions can be specified with the same platform device
> +	  resources as the UIO_PDRV drivers, but dynamic regions can also
> +	  be specified.
> +	  The number and size of these regions is static,
> +	  but the memory allocation is not performed until
> +	  the associated device file is opened. The
> +	  memory is freed once the uio device is closed.
> +
> +	  If you don't know what to do here, say N.
> +
>  config UIO_AEC
>  	tristate "AEC video timestamp device"
>  	depends on PCI
> diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
> index d4dd9a5..b354c53 100644
> --- a/drivers/uio/Makefile
> +++ b/drivers/uio/Makefile
> @@ -2,6 +2,7 @@ obj-$(CONFIG_UIO)	+= uio.o
>  obj-$(CONFIG_UIO_CIF)	+= uio_cif.o
>  obj-$(CONFIG_UIO_PDRV)	+= uio_pdrv.o
>  obj-$(CONFIG_UIO_PDRV_GENIRQ)	+= uio_pdrv_genirq.o
> +obj-$(CONFIG_UIO_DMEM_GENIRQ)	+= uio_dmem_genirq.o
>  obj-$(CONFIG_UIO_AEC)	+= uio_aec.o
>  obj-$(CONFIG_UIO_SERCOS3)	+= uio_sercos3.o
>  obj-$(CONFIG_UIO_PCI_GENERIC)	+= uio_pci_generic.o
> diff --git a/drivers/uio/uio_dmem_genirq.c b/drivers/uio/uio_dmem_genirq.c
> new file mode 100644
> index 0000000..4d4dd00
> --- /dev/null
> +++ b/drivers/uio/uio_dmem_genirq.c
> @@ -0,0 +1,354 @@
> +/*
> + * drivers/uio/uio_dmem_genirq.c
> + *
> + * Userspace I/O platform driver with generic IRQ handling code.
> + *
> + * Copyright (C) 2012 Damian Hobson-Garcia
> + *
> + * Based on uio_pdrv_genirq.c by Magnus Damm
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/platform_device.h>
> +#include <linux/uio_driver.h>
> +#include <linux/spinlock.h>
> +#include <linux/bitops.h>
> +#include <linux/module.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_data/uio_dmem_genirq.h>
> +#include <linux/stringify.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/slab.h>
> +
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/of_address.h>
> +
> +#define DRIVER_NAME "uio_dmem_genirq"
> +
> +struct uio_dmem_genirq_platdata {
> +	struct uio_info *uioinfo;
> +	spinlock_t lock;
> +	unsigned long flags;
> +	struct platform_device *pdev;
> +	unsigned int dmem_region_start;
> +	unsigned int num_dmem_regions;
> +	struct mutex alloc_lock;
> +	unsigned int refcnt;
> +};
> +
> +static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
> +{
> +	struct uio_dmem_genirq_platdata *priv = info->priv;
> +	struct uio_mem *uiomem;
> +	int ret = 0;
> +
> +	uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
> +
> +	mutex_lock(&priv->alloc_lock);
> +	while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
> +		void *addr;
> +		if (!uiomem->size)
> +			break;
> +
> +		addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
> +				(dma_addr_t *)&uiomem->addr, GFP_KERNEL);
> +		if (!addr) {
> +			ret = -ENOMEM;
> +			break;
> +		}
> +
> +		uiomem->internal_addr = addr;
> +		++uiomem;
> +	}
> +	priv->refcnt++;
> +
> +	mutex_unlock(&priv->alloc_lock);
> +	/* Wait until the Runtime PM code has woken up the device */
> +	pm_runtime_get_sync(&priv->pdev->dev);
> +	return ret;
> +}
> +
> +static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
> +{
> +	struct uio_dmem_genirq_platdata *priv = info->priv;
> +	struct uio_mem *uiomem;
> +
> +	/* Tell the Runtime PM code that the device has become idle */
> +	pm_runtime_put_sync(&priv->pdev->dev);
> +
> +	uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
> +
> +	mutex_lock(&priv->alloc_lock);
> +
> +	priv->refcnt--;
> +	while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
> +		if (!uiomem->size)
> +			break;
> +
> +		dma_free_coherent(&priv->pdev->dev, uiomem->size,
> +				uiomem->internal_addr, uiomem->addr);
> +		uiomem->addr = DMA_ERROR_CODE;
> +		++uiomem;
> +	}
> +
> +	mutex_unlock(&priv->alloc_lock);
> +	return 0;
> +}
> +
> +static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
> +{
> +	struct uio_dmem_genirq_platdata *priv = dev_info->priv;
> +
> +	/* Just disable the interrupt in the interrupt controller, and
> +	 * remember the state so we can allow user space to enable it later.
> +	 */
> +
> +	if (!test_and_set_bit(0, &priv->flags))
> +		disable_irq_nosync(irq);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
> +{
> +	struct uio_dmem_genirq_platdata *priv = dev_info->priv;
> +	unsigned long flags;
> +
> +	/* Allow user space to enable and disable the interrupt
> +	 * in the interrupt controller, but keep track of the
> +	 * state to prevent per-irq depth damage.
> +	 *
> +	 * Serialize this operation to support multiple tasks.
> +	 */
> +
> +	spin_lock_irqsave(&priv->lock, flags);
> +	if (irq_on) {
> +		if (test_and_clear_bit(0, &priv->flags))
> +			enable_irq(dev_info->irq);
> +	} else {
> +		if (!test_and_set_bit(0, &priv->flags))
> +			disable_irq(dev_info->irq);
> +	}
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +
> +	return 0;
> +}
> +
> +static int uio_dmem_genirq_probe(struct platform_device *pdev)
> +{
> +	struct uio_dmem_genirq_pdata *pdata = pdev->dev.platform_data;
> +	struct uio_info *uioinfo = &pdata->uioinfo;
> +	struct uio_dmem_genirq_platdata *priv;
> +	struct uio_mem *uiomem;
> +	int ret = -EINVAL;
> +	int i;
> +
> +	if (!uioinfo) {
> +		int irq;
> +
> +		/* alloc uioinfo for one device */
> +		uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
> +		if (!uioinfo) {
> +			ret = -ENOMEM;
> +			dev_err(&pdev->dev, "unable to kmalloc\n");
> +			goto bad2;
> +		}
> +		uioinfo->name = pdev->dev.of_node->name;
> +		uioinfo->version = "devicetree";
> +
> +		/* Multiple IRQs are not supported */
> +		irq = platform_get_irq(pdev, 0);
> +		if (irq == -ENXIO)
> +			uioinfo->irq = UIO_IRQ_NONE;
> +		else
> +			uioinfo->irq = irq;
> +	}
> +
> +	if (!uioinfo || !uioinfo->name || !uioinfo->version) {
> +		dev_err(&pdev->dev, "missing platform_data\n");
> +		goto bad0;
> +	}
> +
> +	if (uioinfo->handler || uioinfo->irqcontrol ||
> +	    uioinfo->irq_flags & IRQF_SHARED) {
> +		dev_err(&pdev->dev, "interrupt configuration error\n");
> +		goto bad0;
> +	}
> +
> +	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> +	if (!priv) {
> +		ret = -ENOMEM;
> +		dev_err(&pdev->dev, "unable to kmalloc\n");
> +		goto bad0;
> +	}
> +
> +	dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
> +
> +	priv->uioinfo = uioinfo;
> +	spin_lock_init(&priv->lock);
> +	priv->flags = 0; /* interrupt is enabled to begin with */
> +	priv->pdev = pdev;
> +	mutex_init(&priv->alloc_lock);
> +
> +	if (!uioinfo->irq) {
> +		ret = platform_get_irq(pdev, 0);
> +		if (ret < 0) {
> +			dev_err(&pdev->dev, "failed to get IRQ\n");
> +			goto bad0;
> +		}
> +		uioinfo->irq = ret;
> +	}
> +	uiomem = &uioinfo->mem[0];
> +
> +	for (i = 0; i < pdev->num_resources; ++i) {
> +		struct resource *r = &pdev->resource[i];
> +
> +		if (r->flags != IORESOURCE_MEM)
> +			continue;
> +
> +		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
> +			dev_warn(&pdev->dev, "device has more than "
> +					__stringify(MAX_UIO_MAPS)
> +					" I/O memory resources.\n");
> +			break;
> +		}
> +
> +		uiomem->memtype = UIO_MEM_PHYS;
> +		uiomem->addr = r->start;
> +		uiomem->size = resource_size(r);
> +		++uiomem;
> +	}
> +
> +	priv->dmem_region_start = i;
> +	priv->num_dmem_regions = pdata->num_dynamic_regions;
> +
> +	for (i = 0; i < pdata->num_dynamic_regions; ++i) {
> +		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
> +			dev_warn(&pdev->dev, "device has more than "
> +					__stringify(MAX_UIO_MAPS)
> +					" dynamic and fixed memory regions.\n");
> +			break;
> +		}
> +		uiomem->memtype = UIO_MEM_PHYS;
> +		uiomem->addr = DMA_ERROR_CODE;
> +		uiomem->size = pdata->dynamic_region_sizes[i];
> +		++uiomem;
> +	}
> +
> +	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
> +		uiomem->size = 0;
> +		++uiomem;
> +	}
> +
> +	/* This driver requires no hardware specific kernel code to handle
> +	 * interrupts. Instead, the interrupt handler simply disables the
> +	 * interrupt in the interrupt controller. User space is responsible
> +	 * for performing hardware specific acknowledge and re-enabling of
> +	 * the interrupt in the interrupt controller.
> +	 *
> +	 * Interrupt sharing is not supported.
> +	 */
> +
> +	uioinfo->handler = uio_dmem_genirq_handler;
> +	uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
> +	uioinfo->open = uio_dmem_genirq_open;
> +	uioinfo->release = uio_dmem_genirq_release;
> +	uioinfo->priv = priv;
> +
> +	/* Enable Runtime PM for this device:
> +	 * The device starts in suspended state to allow the hardware to be
> +	 * turned off by default. The Runtime PM bus code should power on the
> +	 * hardware and enable clocks at open().
> +	 */
> +	pm_runtime_enable(&pdev->dev);
> +
> +	ret = uio_register_device(&pdev->dev, priv->uioinfo);
> +	if (ret) {
> +		dev_err(&pdev->dev, "unable to register uio device\n");
> +		goto bad1;
> +	}
> +
> +	platform_set_drvdata(pdev, priv);
> +	return 0;
> + bad1:
> +	kfree(priv);
> +	pm_runtime_disable(&pdev->dev);
> + bad0:
> +	/* kfree uioinfo for OF */
> +	if (pdev->dev.of_node)
> +		kfree(uioinfo);
> + bad2:
> +	return ret;
> +}
> +
> +static int uio_dmem_genirq_remove(struct platform_device *pdev)
> +{
> +	struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
> +
> +	uio_unregister_device(priv->uioinfo);
> +	pm_runtime_disable(&pdev->dev);
> +
> +	priv->uioinfo->handler = NULL;
> +	priv->uioinfo->irqcontrol = NULL;
> +
> +	/* kfree uioinfo for OF */
> +	if (pdev->dev.of_node)
> +		kfree(priv->uioinfo);
> +
> +	kfree(priv);
> +	return 0;
> +}
> +
> +static int uio_dmem_genirq_runtime_nop(struct device *dev)
> +{
> +	/* Runtime PM callback shared between ->runtime_suspend()
> +	 * and ->runtime_resume(). Simply returns success.
> +	 *
> +	 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
> +	 * are used at open() and release() time. This allows the
> +	 * Runtime PM code to turn off power to the device while the
> +	 * device is unused, ie before open() and after release().
> +	 *
> +	 * This Runtime PM callback does not need to save or restore
> +	 * any registers since user space is responsbile for hardware
> +	 * register reinitialization after open().
> +	 */
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
> +	.runtime_suspend = uio_dmem_genirq_runtime_nop,
> +	.runtime_resume = uio_dmem_genirq_runtime_nop,
> +};
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id uio_of_genirq_match[] = {
> +	{ /* empty for now */ },
> +};
> +MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
> +#else
> +# define uio_of_genirq_match NULL
> +#endif
> +
> +static struct platform_driver uio_dmem_genirq = {
> +	.probe = uio_dmem_genirq_probe,
> +	.remove = uio_dmem_genirq_remove,
> +	.driver = {
> +		.name = DRIVER_NAME,
> +		.owner = THIS_MODULE,
> +		.pm = &uio_dmem_genirq_dev_pm_ops,
> +		.of_match_table = uio_of_genirq_match,
> +	},
> +};
> +
> +module_platform_driver(uio_dmem_genirq);
> +
> +MODULE_AUTHOR("Damian Hobson-Garcia");
> +MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:" DRIVER_NAME);
> diff --git a/include/linux/platform_data/uio_dmem_genirq.h b/include/linux/platform_data/uio_dmem_genirq.h
> new file mode 100644
> index 0000000..973c1bb
> --- /dev/null
> +++ b/include/linux/platform_data/uio_dmem_genirq.h
> @@ -0,0 +1,26 @@
> +/*
> + * include/linux/platform_data/uio_dmem_genirq.h
> + *
> + * Copyright (C) 2012 Damian Hobson-Garcia
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation version 2.
> + *
> + * This program is distributed "as is" WITHOUT ANY WARRANTY of any
> + * kind, whether express or implied; without even the implied warranty
> + * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#ifndef _UIO_DMEM_GENIRQ_H
> +#define _UIO_DMEM_GENIRQ_H
> +
> +#include <linux/uio_driver.h>
> +
> +struct uio_dmem_genirq_pdata {
> +	struct uio_info	uioinfo;
> +	unsigned int *dynamic_region_sizes;
> +	unsigned int num_dynamic_regions;
> +};
> +#endif /* _UIO_DMEM_GENIRQ_H */
> -- 
> 1.7.5.4
> 
> 
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