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/of_platform.h>
27#include <linux/of_address.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 device_node *node = pdev->dev.of_node;
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 (!of_property_read_string(node, "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						       "%pOFn", 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		struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq);
177
178		/*
179		 * If a level interrupt, dont do lazy disable. Otherwise the
180		 * irq will fire again since clearing of the actual cause, on
181		 * device level, is done in userspace
182		 * irqd_is_level_type() isn't used since isn't valid until
183		 * irq is configured.
184		 */
185		if (irq_data &&
186		    irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) {
187			dev_dbg(&pdev->dev, "disable lazy unmask\n");
188			irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
189		}
190	}
191
192	uiomem = &uioinfo->mem[0];
193
194	for (i = 0; i < pdev->num_resources; ++i) {
195		struct resource *r = &pdev->resource[i];
196
197		if (r->flags != IORESOURCE_MEM)
198			continue;
199
200		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
201			dev_warn(&pdev->dev, "device has more than "
202					__stringify(MAX_UIO_MAPS)
203					" I/O memory resources.\n");
204			break;
205		}
206
207		uiomem->memtype = UIO_MEM_PHYS;
208		uiomem->addr = r->start & PAGE_MASK;
209		uiomem->offs = r->start & ~PAGE_MASK;
210		uiomem->size = (uiomem->offs + resource_size(r)
211				+ PAGE_SIZE - 1) & PAGE_MASK;
212		uiomem->name = r->name;
213		++uiomem;
214	}
215
216	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
217		uiomem->size = 0;
218		++uiomem;
219	}
220
221	/* This driver requires no hardware specific kernel code to handle
222	 * interrupts. Instead, the interrupt handler simply disables the
223	 * interrupt in the interrupt controller. User space is responsible
224	 * for performing hardware specific acknowledge and re-enabling of
225	 * the interrupt in the interrupt controller.
226	 *
227	 * Interrupt sharing is not supported.
228	 */
229
230	uioinfo->handler = uio_pdrv_genirq_handler;
231	uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
232	uioinfo->open = uio_pdrv_genirq_open;
233	uioinfo->release = uio_pdrv_genirq_release;
234	uioinfo->priv = priv;
235
236	/* Enable Runtime PM for this device:
237	 * The device starts in suspended state to allow the hardware to be
238	 * turned off by default. The Runtime PM bus code should power on the
239	 * hardware and enable clocks at open().
240	 */
241	pm_runtime_enable(&pdev->dev);
242
243	ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup,
244				       &pdev->dev);
245	if (ret)
246		return ret;
247
248	ret = devm_uio_register_device(&pdev->dev, priv->uioinfo);
249	if (ret)
250		dev_err(&pdev->dev, "unable to register uio device\n");
251
252	return ret;
253}
254
255static int uio_pdrv_genirq_runtime_nop(struct device *dev)
256{
257	/* Runtime PM callback shared between ->runtime_suspend()
258	 * and ->runtime_resume(). Simply returns success.
259	 *
260	 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
261	 * are used at open() and release() time. This allows the
262	 * Runtime PM code to turn off power to the device while the
263	 * device is unused, ie before open() and after release().
264	 *
265	 * This Runtime PM callback does not need to save or restore
266	 * any registers since user space is responsbile for hardware
267	 * register reinitialization after open().
268	 */
269	return 0;
270}
271
272static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
273	.runtime_suspend = uio_pdrv_genirq_runtime_nop,
274	.runtime_resume = uio_pdrv_genirq_runtime_nop,
275};
276
277#ifdef CONFIG_OF
278static struct of_device_id uio_of_genirq_match[] = {
279	{ /* This is filled with module_parm */ },
280	{ /* Sentinel */ },
281};
282MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
283module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
284MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
285#endif
286
287static struct platform_driver uio_pdrv_genirq = {
288	.probe = uio_pdrv_genirq_probe,
289	.driver = {
290		.name = DRIVER_NAME,
291		.pm = &uio_pdrv_genirq_dev_pm_ops,
292		.of_match_table = of_match_ptr(uio_of_genirq_match),
293	},
294};
295
296module_platform_driver(uio_pdrv_genirq);
297
298MODULE_AUTHOR("Magnus Damm");
299MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
300MODULE_LICENSE("GPL v2");
301MODULE_ALIAS("platform:" DRIVER_NAME);
302