[mirror_ubuntu-artful-kernel.git] / drivers / uio / uio_pci_generic.c

/* uio_pci_generic - generic UIO driver for PCI 2.3 devices
 *
 * Copyright (C) 2009 Red Hat, Inc.
 * Author: Michael S. Tsirkin <mst@redhat.com>
 *
 * This work is licensed under the terms of the GNU GPL, version 2.
 *
 * Since the driver does not declare any device ids, you must allocate
 * id and bind the device to the driver yourself.  For example:
 *
 * # echo "8086 10f5" > /sys/bus/pci/drivers/uio_pci_generic/new_id
 * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
 * # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/uio_pci_generic/bind
 * # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
 * .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic
 *
 * Driver won't bind to devices which do not support the Interrupt Disable Bit
 * in the command register. All devices compliant to PCI 2.3 (circa 2002) and
 * all compliant PCI Express devices should support this bit.
 */

#include <linux/device.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/uio_driver.h>

#define DRIVER_VERSION	"0.01.0"
#define DRIVER_AUTHOR	"Michael S. Tsirkin <mst@redhat.com>"
#define DRIVER_DESC	"Generic UIO driver for PCI 2.3 devices"

struct uio_pci_generic_dev {
	struct uio_info info;
	struct pci_dev *pdev;
};

static inline struct uio_pci_generic_dev *
to_uio_pci_generic_dev(struct uio_info *info)
{
	return container_of(info, struct uio_pci_generic_dev, info);
}

/* Interrupt handler. Read/modify/write the command register to disable
 * the interrupt. */
static irqreturn_t irqhandler(int irq, struct uio_info *info)
{
	struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
	struct pci_dev *pdev = gdev->pdev;
	irqreturn_t ret = IRQ_NONE;
	u32 cmd_status_dword;
	u16 origcmd, newcmd, status;

	/* We do a single dword read to retrieve both command and status.
	 * Document assumptions that make this possible. */
	BUILD_BUG_ON(PCI_COMMAND % 4);
	BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS);

	pci_block_user_cfg_access(pdev);

	/* Read both command and status registers in a single 32-bit operation.
	 * Note: we could cache the value for command and move the status read
	 * out of the lock if there was a way to get notified of user changes
	 * to command register through sysfs. Should be good for shared irqs. */
	pci_read_config_dword(pdev, PCI_COMMAND, &cmd_status_dword);
	origcmd = cmd_status_dword;
	status = cmd_status_dword >> 16;

	/* Check interrupt status register to see whether our device
	 * triggered the interrupt. */
	if (!(status & PCI_STATUS_INTERRUPT))
		goto done;

	/* We triggered the interrupt, disable it. */
	newcmd = origcmd | PCI_COMMAND_INTX_DISABLE;
	if (newcmd != origcmd)
		pci_write_config_word(pdev, PCI_COMMAND, newcmd);

	/* UIO core will signal the user process. */
	ret = IRQ_HANDLED;
done:

	pci_unblock_user_cfg_access(pdev);
	return ret;
}

/* Verify that the device supports Interrupt Disable bit in command register,
 * per PCI 2.3, by flipping this bit and reading it back: this bit was readonly
 * in PCI 2.2. */
static int __devinit verify_pci_2_3(struct pci_dev *pdev)
{
	u16 orig, new;
	int err = 0;

	pci_block_user_cfg_access(pdev);
	pci_read_config_word(pdev, PCI_COMMAND, &orig);
	pci_write_config_word(pdev, PCI_COMMAND,
			      orig ^ PCI_COMMAND_INTX_DISABLE);
	pci_read_config_word(pdev, PCI_COMMAND, &new);
	/* There's no way to protect against
	 * hardware bugs or detect them reliably, but as long as we know
	 * what the value should be, let's go ahead and check it. */
	if ((new ^ orig) & ~PCI_COMMAND_INTX_DISABLE) {
		err = -EBUSY;
		dev_err(&pdev->dev, "Command changed from 0x%x to 0x%x: "
			"driver or HW bug?\n", orig, new);
		goto err;
	}
	if (!((new ^ orig) & PCI_COMMAND_INTX_DISABLE)) {
		dev_warn(&pdev->dev, "Device does not support "
			 "disabling interrupts: unable to bind.\n");
		err = -ENODEV;
		goto err;
	}
	/* Now restore the original value. */
	pci_write_config_word(pdev, PCI_COMMAND, orig);
err:
	pci_unblock_user_cfg_access(pdev);
	return err;
}

static int __devinit probe(struct pci_dev *pdev,
			   const struct pci_device_id *id)
{
	struct uio_pci_generic_dev *gdev;
	int err;

	err = pci_enable_device(pdev);
	if (err) {
		dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
			__func__, err);
		return err;
	}

	if (!pdev->irq) {
		dev_warn(&pdev->dev, "No IRQ assigned to device: "
			 "no support for interrupts?\n");
		pci_disable_device(pdev);
		return -ENODEV;
	}

	err = verify_pci_2_3(pdev);
	if (err)
		goto err_verify;

	gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
	if (!gdev) {
		err = -ENOMEM;
		goto err_alloc;
	}

	gdev->info.name = "uio_pci_generic";
	gdev->info.version = DRIVER_VERSION;
	gdev->info.irq = pdev->irq;
	gdev->info.irq_flags = IRQF_SHARED;
	gdev->info.handler = irqhandler;
	gdev->pdev = pdev;

	if (uio_register_device(&pdev->dev, &gdev->info))
		goto err_register;
	pci_set_drvdata(pdev, gdev);

	return 0;
err_register:
	kfree(gdev);
err_alloc:
err_verify:
	pci_disable_device(pdev);
	return err;
}

static void remove(struct pci_dev *pdev)
{
	struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);

	uio_unregister_device(&gdev->info);
	pci_disable_device(pdev);
	kfree(gdev);
}

static struct pci_driver driver = {
	.name = "uio_pci_generic",
	.id_table = NULL, /* only dynamic id's */
	.probe = probe,
	.remove = remove,
};

static int __init init(void)
{
	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
	return pci_register_driver(&driver);
}

static void __exit cleanup(void)
{
	pci_unregister_driver(&driver);
}

module_init(init);
module_exit(cleanup);

MODULE_VERSION(DRIVER_VERSION);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
Commit	Line	Data
ccb86a69 MT	1	/* uio_pci_generic - generic UIO driver for PCI 2.3 devices
	2	*
	3	* Copyright (C) 2009 Red Hat, Inc.
	4	* Author: Michael S. Tsirkin <mst@redhat.com>
	5	*
	6	* This work is licensed under the terms of the GNU GPL, version 2.
	7	*
	8	* Since the driver does not declare any device ids, you must allocate
	9	* id and bind the device to the driver yourself. For example:
	10	*
	11	* # echo "8086 10f5" > /sys/bus/pci/drivers/uio_pci_generic/new_id
	12	* # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/e1000e/unbind
	13	* # echo -n 0000:00:19.0 > /sys/bus/pci/drivers/uio_pci_generic/bind
	14	* # ls -l /sys/bus/pci/devices/0000:00:19.0/driver
	15	* .../0000:00:19.0/driver -> ../../../bus/pci/drivers/uio_pci_generic
	16	*
	17	* Driver won't bind to devices which do not support the Interrupt Disable Bit
	18	* in the command register. All devices compliant to PCI 2.3 (circa 2002) and
	19	* all compliant PCI Express devices should support this bit.
	20	*/
	21
	22	#include <linux/device.h>
	23	#include <linux/module.h>
	24	#include <linux/pci.h>
5a0e3ad6	25	#include <linux/slab.h>
ccb86a69	26	#include <linux/uio_driver.h>
ccb86a69 MT	27
	28	#define DRIVER_VERSION "0.01.0"
	29	#define DRIVER_AUTHOR "Michael S. Tsirkin <mst@redhat.com>"
	30	#define DRIVER_DESC "Generic UIO driver for PCI 2.3 devices"
	31
	32	struct uio_pci_generic_dev {
	33	struct uio_info info;
	34	struct pci_dev *pdev;
ccb86a69 MT	35	};
	36
	37	static inline struct uio_pci_generic_dev *
	38	to_uio_pci_generic_dev(struct uio_info *info)
	39	{
	40	return container_of(info, struct uio_pci_generic_dev, info);
	41	}
	42
	43	/* Interrupt handler. Read/modify/write the command register to disable
	44	* the interrupt. */
	45	static irqreturn_t irqhandler(int irq, struct uio_info *info)
	46	{
	47	struct uio_pci_generic_dev *gdev = to_uio_pci_generic_dev(info);
	48	struct pci_dev *pdev = gdev->pdev;
	49	irqreturn_t ret = IRQ_NONE;
	50	u32 cmd_status_dword;
	51	u16 origcmd, newcmd, status;
	52
	53	/* We do a single dword read to retrieve both command and status.
	54	* Document assumptions that make this possible. */
	55	BUILD_BUG_ON(PCI_COMMAND % 4);
	56	BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS);
	57
ccb86a69 MT	58	pci_block_user_cfg_access(pdev);
	59
	60	/* Read both command and status registers in a single 32-bit operation.
	61	* Note: we could cache the value for command and move the status read
	62	* out of the lock if there was a way to get notified of user changes
	63	* to command register through sysfs. Should be good for shared irqs. */
	64	pci_read_config_dword(pdev, PCI_COMMAND, &cmd_status_dword);
	65	origcmd = cmd_status_dword;
	66	status = cmd_status_dword >> 16;
	67
	68	/* Check interrupt status register to see whether our device
	69	* triggered the interrupt. */
	70	if (!(status & PCI_STATUS_INTERRUPT))
	71	goto done;
	72
	73	/* We triggered the interrupt, disable it. */
	74	newcmd = origcmd \| PCI_COMMAND_INTX_DISABLE;
	75	if (newcmd != origcmd)
	76	pci_write_config_word(pdev, PCI_COMMAND, newcmd);
	77
	78	/* UIO core will signal the user process. */
	79	ret = IRQ_HANDLED;
	80	done:
	81
	82	pci_unblock_user_cfg_access(pdev);
ccb86a69 MT	83	return ret;
	84	}
	85
	86	/* Verify that the device supports Interrupt Disable bit in command register,
	87	* per PCI 2.3, by flipping this bit and reading it back: this bit was readonly
	88	* in PCI 2.2. */
	89	static int __devinit verify_pci_2_3(struct pci_dev *pdev)
	90	{
	91	u16 orig, new;
	92	int err = 0;
	93
	94	pci_block_user_cfg_access(pdev);
	95	pci_read_config_word(pdev, PCI_COMMAND, &orig);
	96	pci_write_config_word(pdev, PCI_COMMAND,
	97	orig ^ PCI_COMMAND_INTX_DISABLE);
	98	pci_read_config_word(pdev, PCI_COMMAND, &new);
	99	/* There's no way to protect against
	100	* hardware bugs or detect them reliably, but as long as we know
	101	* what the value should be, let's go ahead and check it. */
	102	if ((new ^ orig) & ~PCI_COMMAND_INTX_DISABLE) {
	103	err = -EBUSY;
	104	dev_err(&pdev->dev, "Command changed from 0x%x to 0x%x: "
	105	"driver or HW bug?\n", orig, new);
	106	goto err;
	107	}
	108	if (!((new ^ orig) & PCI_COMMAND_INTX_DISABLE)) {
	109	dev_warn(&pdev->dev, "Device does not support "
	110	"disabling interrupts: unable to bind.\n");
	111	err = -ENODEV;
	112	goto err;
	113	}
	114	/* Now restore the original value. */
	115	pci_write_config_word(pdev, PCI_COMMAND, orig);
	116	err:
	117	pci_unblock_user_cfg_access(pdev);
	118	return err;
	119	}
	120
	121	static int __devinit probe(struct pci_dev *pdev,
	122	const struct pci_device_id *id)
	123	{
	124	struct uio_pci_generic_dev *gdev;
	125	int err;
	126
ccb86a69 MT	127	err = pci_enable_device(pdev);
	128	if (err) {
	129	dev_err(&pdev->dev, "%s: pci_enable_device failed: %d\n",
	130	__func__, err);
	131	return err;
	132	}
	133
1037246c KV	134	if (!pdev->irq) {
	135	dev_warn(&pdev->dev, "No IRQ assigned to device: "
	136	"no support for interrupts?\n");
	137	pci_disable_device(pdev);
	138	return -ENODEV;
	139	}
	140
ccb86a69 MT	141	err = verify_pci_2_3(pdev);
	142	if (err)
	143	goto err_verify;
	144
	145	gdev = kzalloc(sizeof(struct uio_pci_generic_dev), GFP_KERNEL);
	146	if (!gdev) {
	147	err = -ENOMEM;
	148	goto err_alloc;
	149	}
	150
	151	gdev->info.name = "uio_pci_generic";
	152	gdev->info.version = DRIVER_VERSION;
	153	gdev->info.irq = pdev->irq;
	154	gdev->info.irq_flags = IRQF_SHARED;
	155	gdev->info.handler = irqhandler;
	156	gdev->pdev = pdev;
ccb86a69 MT	157
	158	if (uio_register_device(&pdev->dev, &gdev->info))
	159	goto err_register;
	160	pci_set_drvdata(pdev, gdev);
	161
	162	return 0;
	163	err_register:
	164	kfree(gdev);
	165	err_alloc:
	166	err_verify:
	167	pci_disable_device(pdev);
	168	return err;
	169	}
	170
	171	static void remove(struct pci_dev *pdev)
	172	{
	173	struct uio_pci_generic_dev *gdev = pci_get_drvdata(pdev);
	174
	175	uio_unregister_device(&gdev->info);
	176	pci_disable_device(pdev);
	177	kfree(gdev);
	178	}
	179
	180	static struct pci_driver driver = {
	181	.name = "uio_pci_generic",
	182	.id_table = NULL, /* only dynamic id's */
	183	.probe = probe,
	184	.remove = remove,
	185	};
	186
	187	static int __init init(void)
	188	{
	189	pr_info(DRIVER_DESC " version: " DRIVER_VERSION "\n");
	190	return pci_register_driver(&driver);
	191	}
	192
	193	static void __exit cleanup(void)
	194	{
	195	pci_unregister_driver(&driver);
	196	}
	197
	198	module_init(init);
	199	module_exit(cleanup);
	200
	201	MODULE_VERSION(DRIVER_VERSION);
	202	MODULE_LICENSE("GPL v2");
	203	MODULE_AUTHOR(DRIVER_AUTHOR);
	204	MODULE_DESCRIPTION(DRIVER_DESC);