1/*
2 * drivers/uio/uio_dmem_genirq.c
3 *
4 * Userspace I/O platform driver with generic IRQ handling code.
5 *
6 * Copyright (C) 2012 Damian Hobson-Garcia
7 *
8 * Based on uio_pdrv_genirq.c by Magnus Damm
9 *
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License version 2 as published by
12 * the Free Software Foundation.
13 */
14
15#include <linux/platform_device.h>
16#include <linux/uio_driver.h>
17#include <linux/spinlock.h>
18#include <linux/bitops.h>
19#include <linux/module.h>
20#include <linux/interrupt.h>
21#include <linux/platform_data/uio_dmem_genirq.h>
22#include <linux/stringify.h>
23#include <linux/pm_runtime.h>
24#include <linux/dma-mapping.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_dmem_genirq"
32#define DMEM_MAP_ERROR (~0)
33
34struct uio_dmem_genirq_platdata {
35	struct uio_info *uioinfo;
36	spinlock_t lock;
37	unsigned long flags;
38	struct platform_device *pdev;
39	unsigned int dmem_region_start;
40	unsigned int num_dmem_regions;
41	void *dmem_region_vaddr[MAX_UIO_MAPS];
42	struct mutex alloc_lock;
43	unsigned int refcnt;
44};
45
46static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
47{
48	struct uio_dmem_genirq_platdata *priv = info->priv;
49	struct uio_mem *uiomem;
50	int ret = 0;
51	int dmem_region = priv->dmem_region_start;
52
53	uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
54
55	mutex_lock(&priv->alloc_lock);
56	while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
57		void *addr;
58		if (!uiomem->size)
59			break;
60
61		addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
62				(dma_addr_t *)&uiomem->addr, GFP_KERNEL);
63		if (!addr) {
64			uiomem->addr = DMEM_MAP_ERROR;
65		}
66		priv->dmem_region_vaddr[dmem_region++] = addr;
67		++uiomem;
68	}
69	priv->refcnt++;
70
71	mutex_unlock(&priv->alloc_lock);
72	/* Wait until the Runtime PM code has woken up the device */
73	pm_runtime_get_sync(&priv->pdev->dev);
74	return ret;
75}
76
77static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
78{
79	struct uio_dmem_genirq_platdata *priv = info->priv;
80	struct uio_mem *uiomem;
81	int dmem_region = priv->dmem_region_start;
82
83	/* Tell the Runtime PM code that the device has become idle */
84	pm_runtime_put_sync(&priv->pdev->dev);
85
86	uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
87
88	mutex_lock(&priv->alloc_lock);
89
90	priv->refcnt--;
91	while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
92		if (!uiomem->size)
93			break;
94		if (priv->dmem_region_vaddr[dmem_region]) {
95			dma_free_coherent(&priv->pdev->dev, uiomem->size,
96					priv->dmem_region_vaddr[dmem_region],
97					uiomem->addr);
98		}
99		uiomem->addr = DMEM_MAP_ERROR;
100		++dmem_region;
101		++uiomem;
102	}
103
104	mutex_unlock(&priv->alloc_lock);
105	return 0;
106}
107
108static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
109{
110	struct uio_dmem_genirq_platdata *priv = dev_info->priv;
111
112	/* Just disable the interrupt in the interrupt controller, and
113	 * remember the state so we can allow user space to enable it later.
114	 */
115
116	if (!test_and_set_bit(0, &priv->flags))
117		disable_irq_nosync(irq);
118
119	return IRQ_HANDLED;
120}
121
122static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
123{
124	struct uio_dmem_genirq_platdata *priv = dev_info->priv;
125	unsigned long flags;
126
127	/* Allow user space to enable and disable the interrupt
128	 * in the interrupt controller, but keep track of the
129	 * state to prevent per-irq depth damage.
130	 *
131	 * Serialize this operation to support multiple tasks.
132	 */
133
134	spin_lock_irqsave(&priv->lock, flags);
135	if (irq_on) {
136		if (test_and_clear_bit(0, &priv->flags))
137			enable_irq(dev_info->irq);
138	} else {
139		if (!test_and_set_bit(0, &priv->flags))
140			disable_irq(dev_info->irq);
141	}
142	spin_unlock_irqrestore(&priv->lock, flags);
143
144	return 0;
145}
146
147static int uio_dmem_genirq_probe(struct platform_device *pdev)
148{
149	struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
150	struct uio_info *uioinfo = &pdata->uioinfo;
151	struct uio_dmem_genirq_platdata *priv;
152	struct uio_mem *uiomem;
153	int ret = -EINVAL;
154	int i;
155
156	if (pdev->dev.of_node) {
157		int irq;
158
159		/* alloc uioinfo for one device */
160		uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
161		if (!uioinfo) {
162			ret = -ENOMEM;
163			dev_err(&pdev->dev, "unable to kmalloc\n");
164			goto bad2;
165		}
166		uioinfo->name = pdev->dev.of_node->name;
167		uioinfo->version = "devicetree";
168
169		/* Multiple IRQs are not supported */
170		irq = platform_get_irq(pdev, 0);
171		if (irq == -ENXIO)
172			uioinfo->irq = UIO_IRQ_NONE;
173		else
174			uioinfo->irq = irq;
175	}
176
177	if (!uioinfo || !uioinfo->name || !uioinfo->version) {
178		dev_err(&pdev->dev, "missing platform_data\n");
179		goto bad0;
180	}
181
182	if (uioinfo->handler || uioinfo->irqcontrol ||
183	    uioinfo->irq_flags & IRQF_SHARED) {
184		dev_err(&pdev->dev, "interrupt configuration error\n");
185		goto bad0;
186	}
187
188	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
189	if (!priv) {
190		ret = -ENOMEM;
191		dev_err(&pdev->dev, "unable to kmalloc\n");
192		goto bad0;
193	}
194
195	dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
196
197	priv->uioinfo = uioinfo;
198	spin_lock_init(&priv->lock);
199	priv->flags = 0; /* interrupt is enabled to begin with */
200	priv->pdev = pdev;
201	mutex_init(&priv->alloc_lock);
202
203	if (!uioinfo->irq) {
204		ret = platform_get_irq(pdev, 0);
205		if (ret < 0) {
206			dev_err(&pdev->dev, "failed to get IRQ\n");
207			goto bad1;
208		}
209		uioinfo->irq = ret;
210	}
211	uiomem = &uioinfo->mem[0];
212
213	for (i = 0; i < pdev->num_resources; ++i) {
214		struct resource *r = &pdev->resource[i];
215
216		if (r->flags != IORESOURCE_MEM)
217			continue;
218
219		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
220			dev_warn(&pdev->dev, "device has more than "
221					__stringify(MAX_UIO_MAPS)
222					" I/O memory resources.\n");
223			break;
224		}
225
226		uiomem->memtype = UIO_MEM_PHYS;
227		uiomem->addr = r->start;
228		uiomem->size = resource_size(r);
229		++uiomem;
230	}
231
232	priv->dmem_region_start = i;
233	priv->num_dmem_regions = pdata->num_dynamic_regions;
234
235	for (i = 0; i < pdata->num_dynamic_regions; ++i) {
236		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
237			dev_warn(&pdev->dev, "device has more than "
238					__stringify(MAX_UIO_MAPS)
239					" dynamic and fixed memory regions.\n");
240			break;
241		}
242		uiomem->memtype = UIO_MEM_PHYS;
243		uiomem->addr = DMEM_MAP_ERROR;
244		uiomem->size = pdata->dynamic_region_sizes[i];
245		++uiomem;
246	}
247
248	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
249		uiomem->size = 0;
250		++uiomem;
251	}
252
253	/* This driver requires no hardware specific kernel code to handle
254	 * interrupts. Instead, the interrupt handler simply disables the
255	 * interrupt in the interrupt controller. User space is responsible
256	 * for performing hardware specific acknowledge and re-enabling of
257	 * the interrupt in the interrupt controller.
258	 *
259	 * Interrupt sharing is not supported.
260	 */
261
262	uioinfo->handler = uio_dmem_genirq_handler;
263	uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
264	uioinfo->open = uio_dmem_genirq_open;
265	uioinfo->release = uio_dmem_genirq_release;
266	uioinfo->priv = priv;
267
268	/* Enable Runtime PM for this device:
269	 * The device starts in suspended state to allow the hardware to be
270	 * turned off by default. The Runtime PM bus code should power on the
271	 * hardware and enable clocks at open().
272	 */
273	pm_runtime_enable(&pdev->dev);
274
275	ret = uio_register_device(&pdev->dev, priv->uioinfo);
276	if (ret) {
277		dev_err(&pdev->dev, "unable to register uio device\n");
278		pm_runtime_disable(&pdev->dev);
279		goto bad1;
280	}
281
282	platform_set_drvdata(pdev, priv);
283	return 0;
284 bad1:
285	kfree(priv);
286 bad0:
287	/* kfree uioinfo for OF */
288	if (pdev->dev.of_node)
289		kfree(uioinfo);
290 bad2:
291	return ret;
292}
293
294static int uio_dmem_genirq_remove(struct platform_device *pdev)
295{
296	struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
297
298	uio_unregister_device(priv->uioinfo);
299	pm_runtime_disable(&pdev->dev);
300
301	priv->uioinfo->handler = NULL;
302	priv->uioinfo->irqcontrol = NULL;
303
304	/* kfree uioinfo for OF */
305	if (pdev->dev.of_node)
306		kfree(priv->uioinfo);
307
308	kfree(priv);
309	return 0;
310}
311
312static int uio_dmem_genirq_runtime_nop(struct device *dev)
313{
314	/* Runtime PM callback shared between ->runtime_suspend()
315	 * and ->runtime_resume(). Simply returns success.
316	 *
317	 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
318	 * are used at open() and release() time. This allows the
319	 * Runtime PM code to turn off power to the device while the
320	 * device is unused, ie before open() and after release().
321	 *
322	 * This Runtime PM callback does not need to save or restore
323	 * any registers since user space is responsbile for hardware
324	 * register reinitialization after open().
325	 */
326	return 0;
327}
328
329static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
330	.runtime_suspend = uio_dmem_genirq_runtime_nop,
331	.runtime_resume = uio_dmem_genirq_runtime_nop,
332};
333
334#ifdef CONFIG_OF
335static const struct of_device_id uio_of_genirq_match[] = {
336	{ /* empty for now */ },
337};
338MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
339#endif
340
341static struct platform_driver uio_dmem_genirq = {
342	.probe = uio_dmem_genirq_probe,
343	.remove = uio_dmem_genirq_remove,
344	.driver = {
345		.name = DRIVER_NAME,
346		.owner = THIS_MODULE,
347		.pm = &uio_dmem_genirq_dev_pm_ops,
348		.of_match_table = of_match_ptr(uio_of_genirq_match),
349	},
350};
351
352module_platform_driver(uio_dmem_genirq);
353
354MODULE_AUTHOR("Damian Hobson-Garcia");
355MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
356MODULE_LICENSE("GPL v2");
357MODULE_ALIAS("platform:" DRIVER_NAME);
358