uio_pdrv_genirq.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * drivers/uio/uio_pdrv_genirq.c
  4 *
  5 * Userspace I/O platform driver with generic IRQ handling code.
  6 *
  7 * Copyright (C) 2008 Magnus Damm
  8 *
  9 * Based on uio_pdrv.c by Uwe Kleine-Koenig,
 10 * Copyright (C) 2008 by Digi International Inc.
 11 * All rights reserved.
 12 */
 13
 14#include <linux/platform_device.h>
 15#include <linux/uio_driver.h>
 16#include <linux/spinlock.h>
 17#include <linux/bitops.h>
 18#include <linux/module.h>
 19#include <linux/interrupt.h>
 20#include <linux/stringify.h>
 21#include <linux/pm_runtime.h>
 22#include <linux/slab.h>
 23#include <linux/irq.h>
 24
 25#include <linux/of.h>
 26#include <linux/mod_devicetable.h>
 27#include <linux/property.h>
 28
 29#define DRIVER_NAME "uio_pdrv_genirq"
 30
 31struct uio_pdrv_genirq_platdata {
 32	struct uio_info *uioinfo;
 33	spinlock_t lock;
 34	unsigned long flags;
 35	struct platform_device *pdev;
 36};
 37
 38/* Bits in uio_pdrv_genirq_platdata.flags */
 39enum {
 40	UIO_IRQ_DISABLED = 0,
 41};
 42
 43static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
 44{
 45	struct uio_pdrv_genirq_platdata *priv = info->priv;
 46
 47	/* Wait until the Runtime PM code has woken up the device */
 48	pm_runtime_get_sync(&priv->pdev->dev);
 49	return 0;
 50}
 51
 52static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
 53{
 54	struct uio_pdrv_genirq_platdata *priv = info->priv;
 55
 56	/* Tell the Runtime PM code that the device has become idle */
 57	pm_runtime_put_sync(&priv->pdev->dev);
 58	return 0;
 59}
 60
 61static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
 62{
 63	struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
 64
 65	/* Just disable the interrupt in the interrupt controller, and
 66	 * remember the state so we can allow user space to enable it later.
 67	 */
 68
 69	spin_lock(&priv->lock);
 70	if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
 71		disable_irq_nosync(irq);
 72	spin_unlock(&priv->lock);
 73
 74	return IRQ_HANDLED;
 75}
 76
 77static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
 78{
 79	struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
 80	unsigned long flags;
 81
 82	/* Allow user space to enable and disable the interrupt
 83	 * in the interrupt controller, but keep track of the
 84	 * state to prevent per-irq depth damage.
 85	 *
 86	 * Serialize this operation to support multiple tasks and concurrency
 87	 * with irq handler on SMP systems.
 88	 */
 89
 90	spin_lock_irqsave(&priv->lock, flags);
 91	if (irq_on) {
 92		if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
 93			enable_irq(dev_info->irq);
 94	} else {
 95		if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
 96			disable_irq_nosync(dev_info->irq);
 97	}
 98	spin_unlock_irqrestore(&priv->lock, flags);
 99
100	return 0;
101}
102
103static void uio_pdrv_genirq_cleanup(void *data)
104{
105	struct device *dev = data;
106
107	pm_runtime_disable(dev);
108}
109
110static int uio_pdrv_genirq_probe(struct platform_device *pdev)
111{
112	struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
113	struct fwnode_handle *node = dev_fwnode(&pdev->dev);
114	struct uio_pdrv_genirq_platdata *priv;
115	struct uio_mem *uiomem;
116	int ret = -EINVAL;
117	int i;
118
119	if (node) {
120		const char *name;
121
122		/* alloc uioinfo for one device */
123		uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo),
124				       GFP_KERNEL);
125		if (!uioinfo) {
126			dev_err(&pdev->dev, "unable to kmalloc\n");
127			return -ENOMEM;
128		}
129
130		if (!device_property_read_string(&pdev->dev, "linux,uio-name", &name))
131			uioinfo->name = devm_kstrdup(&pdev->dev, name, GFP_KERNEL);
132		else
133			uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL,
134						       "%pfwP", node);
135
136		uioinfo->version = "devicetree";
137		/* Multiple IRQs are not supported */
138	}
139
140	if (!uioinfo || !uioinfo->name || !uioinfo->version) {
141		dev_err(&pdev->dev, "missing platform_data\n");
142		return ret;
143	}
144
145	if (uioinfo->handler || uioinfo->irqcontrol ||
146	    uioinfo->irq_flags & IRQF_SHARED) {
147		dev_err(&pdev->dev, "interrupt configuration error\n");
148		return ret;
149	}
150
151	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
152	if (!priv) {
153		dev_err(&pdev->dev, "unable to kmalloc\n");
154		return -ENOMEM;
155	}
156
157	priv->uioinfo = uioinfo;
158	spin_lock_init(&priv->lock);
159	priv->flags = 0; /* interrupt is enabled to begin with */
160	priv->pdev = pdev;
161
162	if (!uioinfo->irq) {
163		ret = platform_get_irq_optional(pdev, 0);
164		uioinfo->irq = ret;
165		if (ret == -ENXIO)
166			uioinfo->irq = UIO_IRQ_NONE;
167		else if (ret == -EPROBE_DEFER)
168			return ret;
169		else if (ret < 0) {
170			dev_err(&pdev->dev, "failed to get IRQ\n");
171			return ret;
172		}
173	}
174
175	if (uioinfo->irq) {
176		/*
177		 * If a level interrupt, dont do lazy disable. Otherwise the
178		 * irq will fire again since clearing of the actual cause, on
179		 * device level, is done in userspace
180		 * irqd_is_level_type() isn't used since isn't valid until
181		 * irq is configured.
182		 */
183		if (irq_get_trigger_type(uioinfo->irq) & IRQ_TYPE_LEVEL_MASK) {
184			dev_dbg(&pdev->dev, "disable lazy unmask\n");
185			irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
186		}
187	}
188
189	uiomem = &uioinfo->mem[0];
190
191	for (i = 0; i < pdev->num_resources; ++i) {
192		struct resource *r = &pdev->resource[i];
193
194		if (r->flags != IORESOURCE_MEM)
195			continue;
196
197		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
198			dev_warn(&pdev->dev, "device has more than "
199					__stringify(MAX_UIO_MAPS)
200					" I/O memory resources.\n");
201			break;
202		}
203
204		uiomem->memtype = UIO_MEM_PHYS;
205		uiomem->addr = r->start & PAGE_MASK;
206		uiomem->offs = r->start & ~PAGE_MASK;
207		uiomem->size = (uiomem->offs + resource_size(r)
208				+ PAGE_SIZE - 1) & PAGE_MASK;
209		uiomem->name = r->name;
210		++uiomem;
211	}
212
213	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
214		uiomem->size = 0;
215		++uiomem;
216	}
217
218	/* This driver requires no hardware specific kernel code to handle
219	 * interrupts. Instead, the interrupt handler simply disables the
220	 * interrupt in the interrupt controller. User space is responsible
221	 * for performing hardware specific acknowledge and re-enabling of
222	 * the interrupt in the interrupt controller.
223	 *
224	 * Interrupt sharing is not supported.
225	 */
226
227	uioinfo->handler = uio_pdrv_genirq_handler;
228	uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
229	uioinfo->open = uio_pdrv_genirq_open;
230	uioinfo->release = uio_pdrv_genirq_release;
231	uioinfo->priv = priv;
232
233	/* Enable Runtime PM for this device:
234	 * The device starts in suspended state to allow the hardware to be
235	 * turned off by default. The Runtime PM bus code should power on the
236	 * hardware and enable clocks at open().
237	 */
238	pm_runtime_enable(&pdev->dev);
239
240	ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup,
241				       &pdev->dev);
242	if (ret)
243		return ret;
244
245	ret = devm_uio_register_device(&pdev->dev, priv->uioinfo);
246	if (ret)
247		dev_err(&pdev->dev, "unable to register uio device\n");
248
249	return ret;
250}
251
252#ifdef CONFIG_OF
253static struct of_device_id uio_of_genirq_match[] = {
254	{ /* This is filled with module_parm */ },
255	{ /* Sentinel */ },
256};
257module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
258MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
259#endif
260
261static struct platform_driver uio_pdrv_genirq = {
262	.probe = uio_pdrv_genirq_probe,
263	.driver = {
264		.name = DRIVER_NAME,
265		.of_match_table = of_match_ptr(uio_of_genirq_match),
266	},
267};
268
269module_platform_driver(uio_pdrv_genirq);
270
271MODULE_AUTHOR("Magnus Damm");
272MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
273MODULE_LICENSE("GPL v2");
274MODULE_ALIAS("platform:" DRIVER_NAME);