1/*
2 * drivers/uio/uio_pdrv_genirq.c
3 *
4 * Userspace I/O platform driver with generic IRQ handling code.
5 *
6 * Copyright (C) 2008 Magnus Damm
7 *
8 * Based on uio_pdrv.c by Uwe Kleine-Koenig,
9 * Copyright (C) 2008 by Digi International Inc.
10 * All rights reserved.
11 *
12 * This program is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License version 2 as published by
14 * the Free Software Foundation.
15 */
16
17#include <linux/platform_device.h>
18#include <linux/uio_driver.h>
19#include <linux/spinlock.h>
20#include <linux/bitops.h>
21#include <linux/module.h>
22#include <linux/interrupt.h>
23#include <linux/stringify.h>
24#include <linux/pm_runtime.h>
25#include <linux/slab.h>
26
27#include <linux/of.h>
28#include <linux/of_platform.h>
29#include <linux/of_address.h>
30
31#define DRIVER_NAME "uio_pdrv_genirq"
32
33struct uio_pdrv_genirq_platdata {
34	struct uio_info *uioinfo;
35	spinlock_t lock;
36	unsigned long flags;
37	struct platform_device *pdev;
38};
39
40/* Bits in uio_pdrv_genirq_platdata.flags */
41enum {
42	UIO_IRQ_DISABLED = 0,
43};
44
45static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
46{
47	struct uio_pdrv_genirq_platdata *priv = info->priv;
48
49	/* Wait until the Runtime PM code has woken up the device */
50	pm_runtime_get_sync(&priv->pdev->dev);
51	return 0;
52}
53
54static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
55{
56	struct uio_pdrv_genirq_platdata *priv = info->priv;
57
58	/* Tell the Runtime PM code that the device has become idle */
59	pm_runtime_put_sync(&priv->pdev->dev);
60	return 0;
61}
62
63static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
64{
65	struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
66
67	/* Just disable the interrupt in the interrupt controller, and
68	 * remember the state so we can allow user space to enable it later.
69	 */
70
71	spin_lock(&priv->lock);
72	if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
73		disable_irq_nosync(irq);
74	spin_unlock(&priv->lock);
75
76	return IRQ_HANDLED;
77}
78
79static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
80{
81	struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
82	unsigned long flags;
83
84	/* Allow user space to enable and disable the interrupt
85	 * in the interrupt controller, but keep track of the
86	 * state to prevent per-irq depth damage.
87	 *
88	 * Serialize this operation to support multiple tasks and concurrency
89	 * with irq handler on SMP systems.
90	 */
91
92	spin_lock_irqsave(&priv->lock, flags);
93	if (irq_on) {
94		if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
95			enable_irq(dev_info->irq);
96	} else {
97		if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
98			disable_irq_nosync(dev_info->irq);
99	}
100	spin_unlock_irqrestore(&priv->lock, flags);
101
102	return 0;
103}
104
105static int uio_pdrv_genirq_probe(struct platform_device *pdev)
106{
107	struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
108	struct uio_pdrv_genirq_platdata *priv;
109	struct uio_mem *uiomem;
110	int ret = -EINVAL;
111	int i;
112
113	if (pdev->dev.of_node) {
114		/* alloc uioinfo for one device */
115		uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo),
116				       GFP_KERNEL);
117		if (!uioinfo) {
118			dev_err(&pdev->dev, "unable to kmalloc\n");
119			return -ENOMEM;
120		}
121		uioinfo->name = pdev->dev.of_node->name;
122		uioinfo->version = "devicetree";
123		/* Multiple IRQs are not supported */
124	}
125
126	if (!uioinfo || !uioinfo->name || !uioinfo->version) {
127		dev_err(&pdev->dev, "missing platform_data\n");
128		return ret;
129	}
130
131	if (uioinfo->handler || uioinfo->irqcontrol ||
132	    uioinfo->irq_flags & IRQF_SHARED) {
133		dev_err(&pdev->dev, "interrupt configuration error\n");
134		return ret;
135	}
136
137	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
138	if (!priv) {
139		dev_err(&pdev->dev, "unable to kmalloc\n");
140		return -ENOMEM;
141	}
142
143	priv->uioinfo = uioinfo;
144	spin_lock_init(&priv->lock);
145	priv->flags = 0; /* interrupt is enabled to begin with */
146	priv->pdev = pdev;
147
148	if (!uioinfo->irq) {
149		ret = platform_get_irq(pdev, 0);
150		uioinfo->irq = ret;
151		if (ret == -ENXIO && pdev->dev.of_node)
152			uioinfo->irq = UIO_IRQ_NONE;
153		else if (ret < 0) {
154			dev_err(&pdev->dev, "failed to get IRQ\n");
155			return ret;
156		}
157	}
158
159	uiomem = &uioinfo->mem[0];
160
161	for (i = 0; i < pdev->num_resources; ++i) {
162		struct resource *r = &pdev->resource[i];
163
164		if (r->flags != IORESOURCE_MEM)
165			continue;
166
167		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
168			dev_warn(&pdev->dev, "device has more than "
169					__stringify(MAX_UIO_MAPS)
170					" I/O memory resources.\n");
171			break;
172		}
173
174		uiomem->memtype = UIO_MEM_PHYS;
175		uiomem->addr = r->start;
176		uiomem->size = resource_size(r);
177		uiomem->name = r->name;
178		++uiomem;
179	}
180
181	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
182		uiomem->size = 0;
183		++uiomem;
184	}
185
186	/* This driver requires no hardware specific kernel code to handle
187	 * interrupts. Instead, the interrupt handler simply disables the
188	 * interrupt in the interrupt controller. User space is responsible
189	 * for performing hardware specific acknowledge and re-enabling of
190	 * the interrupt in the interrupt controller.
191	 *
192	 * Interrupt sharing is not supported.
193	 */
194
195	uioinfo->handler = uio_pdrv_genirq_handler;
196	uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
197	uioinfo->open = uio_pdrv_genirq_open;
198	uioinfo->release = uio_pdrv_genirq_release;
199	uioinfo->priv = priv;
200
201	/* Enable Runtime PM for this device:
202	 * The device starts in suspended state to allow the hardware to be
203	 * turned off by default. The Runtime PM bus code should power on the
204	 * hardware and enable clocks at open().
205	 */
206	pm_runtime_enable(&pdev->dev);
207
208	ret = uio_register_device(&pdev->dev, priv->uioinfo);
209	if (ret) {
210		dev_err(&pdev->dev, "unable to register uio device\n");
211		pm_runtime_disable(&pdev->dev);
212		return ret;
213	}
214
215	platform_set_drvdata(pdev, priv);
216	return 0;
217}
218
219static int uio_pdrv_genirq_remove(struct platform_device *pdev)
220{
221	struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
222
223	uio_unregister_device(priv->uioinfo);
224	pm_runtime_disable(&pdev->dev);
225
226	priv->uioinfo->handler = NULL;
227	priv->uioinfo->irqcontrol = NULL;
228
229	return 0;
230}
231
232static int uio_pdrv_genirq_runtime_nop(struct device *dev)
233{
234	/* Runtime PM callback shared between ->runtime_suspend()
235	 * and ->runtime_resume(). Simply returns success.
236	 *
237	 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
238	 * are used at open() and release() time. This allows the
239	 * Runtime PM code to turn off power to the device while the
240	 * device is unused, ie before open() and after release().
241	 *
242	 * This Runtime PM callback does not need to save or restore
243	 * any registers since user space is responsbile for hardware
244	 * register reinitialization after open().
245	 */
246	return 0;
247}
248
249static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
250	.runtime_suspend = uio_pdrv_genirq_runtime_nop,
251	.runtime_resume = uio_pdrv_genirq_runtime_nop,
252};
253
254#ifdef CONFIG_OF
255static struct of_device_id uio_of_genirq_match[] = {
256	{ /* This is filled with module_parm */ },
257	{ /* Sentinel */ },
258};
259MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
260module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
261MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
262#endif
263
264static struct platform_driver uio_pdrv_genirq = {
265	.probe = uio_pdrv_genirq_probe,
266	.remove = uio_pdrv_genirq_remove,
267	.driver = {
268		.name = DRIVER_NAME,
269		.pm = &uio_pdrv_genirq_dev_pm_ops,
270		.of_match_table = of_match_ptr(uio_of_genirq_match),
271	},
272};
273
274module_platform_driver(uio_pdrv_genirq);
275
276MODULE_AUTHOR("Magnus Damm");
277MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
278MODULE_LICENSE("GPL v2");
279MODULE_ALIAS("platform:" DRIVER_NAME);
280