aboutsummaryrefslogtreecommitdiff
path: root/drivers/uio/uio_dmem_genirq.c
blob: 125d0e5a68879c2953ce1a595f1f325de5730aad (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
/*
 * drivers/uio/uio_dmem_genirq.c
 *
 * Userspace I/O platform driver with generic IRQ handling code.
 *
 * Copyright (C) 2012 Damian Hobson-Garcia
 *
 * Based on uio_pdrv_genirq.c by Magnus Damm
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/platform_device.h>
#include <linux/uio_driver.h>
#include <linux/spinlock.h>
#include <linux/bitops.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/platform_data/uio_dmem_genirq.h>
#include <linux/stringify.h>
#include <linux/pm_runtime.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>

#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/of_address.h>

#define DRIVER_NAME "uio_dmem_genirq"
#define DMEM_MAP_ERROR (~0)

struct uio_dmem_genirq_platdata {
	struct uio_info *uioinfo;
	spinlock_t lock;
	unsigned long flags;
	struct platform_device *pdev;
	unsigned int dmem_region_start;
	unsigned int num_dmem_regions;
	void *dmem_region_vaddr[MAX_UIO_MAPS];
	struct mutex alloc_lock;
	unsigned int refcnt;
};

static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
{
	struct uio_dmem_genirq_platdata *priv = info->priv;
	struct uio_mem *uiomem;
	int ret = 0;
	int dmem_region = priv->dmem_region_start;

	uiomem = &priv->uioinfo->mem[priv->dmem_region_start];

	mutex_lock(&priv->alloc_lock);
	while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
		void *addr;
		if (!uiomem->size)
			break;

		addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
				(dma_addr_t *)&uiomem->addr, GFP_KERNEL);
		if (!addr) {
			uiomem->addr = DMEM_MAP_ERROR;
		}
		priv->dmem_region_vaddr[dmem_region++] = addr;
		++uiomem;
	}
	priv->refcnt++;

	mutex_unlock(&priv->alloc_lock);
	/* Wait until the Runtime PM code has woken up the device */
	pm_runtime_get_sync(&priv->pdev->dev);
	return ret;
}

static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
{
	struct uio_dmem_genirq_platdata *priv = info->priv;
	struct uio_mem *uiomem;
	int dmem_region = priv->dmem_region_start;

	/* Tell the Runtime PM code that the device has become idle */
	pm_runtime_put_sync(&priv->pdev->dev);

	uiomem = &priv->uioinfo->mem[priv->dmem_region_start];

	mutex_lock(&priv->alloc_lock);

	priv->refcnt--;
	while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
		if (!uiomem->size)
			break;
		if (priv->dmem_region_vaddr[dmem_region]) {
			dma_free_coherent(&priv->pdev->dev, uiomem->size,
					priv->dmem_region_vaddr[dmem_region],
					uiomem->addr);
		}
		uiomem->addr = DMEM_MAP_ERROR;
		++dmem_region;
		++uiomem;
	}

	mutex_unlock(&priv->alloc_lock);
	return 0;
}

static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
{
	struct uio_dmem_genirq_platdata *priv = dev_info->priv;

	/* Just disable the interrupt in the interrupt controller, and
	 * remember the state so we can allow user space to enable it later.
	 */

	if (!test_and_set_bit(0, &priv->flags))
		disable_irq_nosync(irq);

	return IRQ_HANDLED;
}

static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
{
	struct uio_dmem_genirq_platdata *priv = dev_info->priv;
	unsigned long flags;

	/* Allow user space to enable and disable the interrupt
	 * in the interrupt controller, but keep track of the
	 * state to prevent per-irq depth damage.
	 *
	 * Serialize this operation to support multiple tasks.
	 */

	spin_lock_irqsave(&priv->lock, flags);
	if (irq_on) {
		if (test_and_clear_bit(0, &priv->flags))
			enable_irq(dev_info->irq);
	} else {
		if (!test_and_set_bit(0, &priv->flags))
			disable_irq(dev_info->irq);
	}
	spin_unlock_irqrestore(&priv->lock, flags);

	return 0;
}

static int uio_dmem_genirq_probe(struct platform_device *pdev)
{
	struct uio_dmem_genirq_pdata *pdata = pdev->dev.platform_data;
	struct uio_info *uioinfo = &pdata->uioinfo;
	struct uio_dmem_genirq_platdata *priv;
	struct uio_mem *uiomem;
	int ret = -EINVAL;
	int i;

	if (pdev->dev.of_node) {
		int irq;

		/* alloc uioinfo for one device */
		uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
		if (!uioinfo) {
			ret = -ENOMEM;
			dev_err(&pdev->dev, "unable to kmalloc\n");
			goto bad2;
		}
		uioinfo->name = pdev->dev.of_node->name;
		uioinfo->version = "devicetree";

		/* Multiple IRQs are not supported */
		irq = platform_get_irq(pdev, 0);
		if (irq == -ENXIO)
			uioinfo->irq = UIO_IRQ_NONE;
		else
			uioinfo->irq = irq;
	}

	if (!uioinfo || !uioinfo->name || !uioinfo->version) {
		dev_err(&pdev->dev, "missing platform_data\n");
		goto bad0;
	}

	if (uioinfo->handler || uioinfo->irqcontrol ||
	    uioinfo->irq_flags & IRQF_SHARED) {
		dev_err(&pdev->dev, "interrupt configuration error\n");
		goto bad0;
	}

	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv) {
		ret = -ENOMEM;
		dev_err(&pdev->dev, "unable to kmalloc\n");
		goto bad0;
	}

	dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));

	priv->uioinfo = uioinfo;
	spin_lock_init(&priv->lock);
	priv->flags = 0; /* interrupt is enabled to begin with */
	priv->pdev = pdev;
	mutex_init(&priv->alloc_lock);

	if (!uioinfo->irq) {
		ret = platform_get_irq(pdev, 0);
		if (ret < 0) {
			dev_err(&pdev->dev, "failed to get IRQ\n");
			goto bad0;
		}
		uioinfo->irq = ret;
	}
	uiomem = &uioinfo->mem[0];

	for (i = 0; i < pdev->num_resources; ++i) {
		struct resource *r = &pdev->resource[i];

		if (r->flags != IORESOURCE_MEM)
			continue;

		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
			dev_warn(&pdev->dev, "device has more than "
					__stringify(MAX_UIO_MAPS)
					" I/O memory resources.\n");
			break;
		}

		uiomem->memtype = UIO_MEM_PHYS;
		uiomem->addr = r->start;
		uiomem->size = resource_size(r);
		++uiomem;
	}

	priv->dmem_region_start = i;
	priv->num_dmem_regions = pdata->num_dynamic_regions;

	for (i = 0; i < pdata->num_dynamic_regions; ++i) {
		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
			dev_warn(&pdev->dev, "device has more than "
					__stringify(MAX_UIO_MAPS)
					" dynamic and fixed memory regions.\n");
			break;
		}
		uiomem->memtype = UIO_MEM_PHYS;
		uiomem->addr = DMEM_MAP_ERROR;
		uiomem->size = pdata->dynamic_region_sizes[i];
		++uiomem;
	}

	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
		uiomem->size = 0;
		++uiomem;
	}

	/* This driver requires no hardware specific kernel code to handle
	 * interrupts. Instead, the interrupt handler simply disables the
	 * interrupt in the interrupt controller. User space is responsible
	 * for performing hardware specific acknowledge and re-enabling of
	 * the interrupt in the interrupt controller.
	 *
	 * Interrupt sharing is not supported.
	 */

	uioinfo->handler = uio_dmem_genirq_handler;
	uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
	uioinfo->open = uio_dmem_genirq_open;
	uioinfo->release = uio_dmem_genirq_release;
	uioinfo->priv = priv;

	/* Enable Runtime PM for this device:
	 * The device starts in suspended state to allow the hardware to be
	 * turned off by default. The Runtime PM bus code should power on the
	 * hardware and enable clocks at open().
	 */
	pm_runtime_enable(&pdev->dev);

	ret = uio_register_device(&pdev->dev, priv->uioinfo);
	if (ret) {
		dev_err(&pdev->dev, "unable to register uio device\n");
		goto bad1;
	}

	platform_set_drvdata(pdev, priv);
	return 0;
 bad1:
	kfree(priv);
	pm_runtime_disable(&pdev->dev);
 bad0:
	/* kfree uioinfo for OF */
	if (pdev->dev.of_node)
		kfree(uioinfo);
 bad2:
	return ret;
}

static int uio_dmem_genirq_remove(struct platform_device *pdev)
{
	struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);

	uio_unregister_device(priv->uioinfo);
	pm_runtime_disable(&pdev->dev);

	priv->uioinfo->handler = NULL;
	priv->uioinfo->irqcontrol = NULL;

	/* kfree uioinfo for OF */
	if (pdev->dev.of_node)
		kfree(priv->uioinfo);

	kfree(priv);
	return 0;
}

static int uio_dmem_genirq_runtime_nop(struct device *dev)
{
	/* Runtime PM callback shared between ->runtime_suspend()
	 * and ->runtime_resume(). Simply returns success.
	 *
	 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
	 * are used at open() and release() time. This allows the
	 * Runtime PM code to turn off power to the device while the
	 * device is unused, ie before open() and after release().
	 *
	 * This Runtime PM callback does not need to save or restore
	 * any registers since user space is responsbile for hardware
	 * register reinitialization after open().
	 */
	return 0;
}

static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
	.runtime_suspend = uio_dmem_genirq_runtime_nop,
	.runtime_resume = uio_dmem_genirq_runtime_nop,
};

#ifdef CONFIG_OF
static const struct of_device_id uio_of_genirq_match[] = {
	{ /* empty for now */ },
};
MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
#endif

static struct platform_driver uio_dmem_genirq = {
	.probe = uio_dmem_genirq_probe,
	.remove = uio_dmem_genirq_remove,
	.driver = {
		.name = DRIVER_NAME,
		.owner = THIS_MODULE,
		.pm = &uio_dmem_genirq_dev_pm_ops,
		.of_match_table = of_match_ptr(uio_of_genirq_match),
	},
};

module_platform_driver(uio_dmem_genirq);

MODULE_AUTHOR("Damian Hobson-Garcia");
MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:" DRIVER_NAME);