xref: /linux/drivers/uio/uio_dmem_genirq.c (revision f86fd32d) 
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * drivers/uio/uio_dmem_genirq.c
4  *
5  * Userspace I/O platform driver with generic IRQ handling code.
6  *
7  * Copyright (C) 2012 Damian Hobson-Garcia
8  *
9  * Based on uio_pdrv_genirq.c by Magnus Damm
10  */
11 
12 #include <linux/platform_device.h>
13 #include <linux/uio_driver.h>
14 #include <linux/spinlock.h>
15 #include <linux/bitops.h>
16 #include <linux/module.h>
17 #include <linux/interrupt.h>
18 #include <linux/platform_data/uio_dmem_genirq.h>
19 #include <linux/stringify.h>
20 #include <linux/pm_runtime.h>
21 #include <linux/dma-mapping.h>
22 #include <linux/slab.h>
23 
24 #include <linux/of.h>
25 #include <linux/of_platform.h>
26 #include <linux/of_address.h>
27 
28 #define DRIVER_NAME "uio_dmem_genirq"
29 #define DMEM_MAP_ERROR (~0)
30 
31 struct uio_dmem_genirq_platdata {
32 	struct uio_info *uioinfo;
33 	spinlock_t lock;
34 	unsigned long flags;
35 	struct platform_device *pdev;
36 	unsigned int dmem_region_start;
37 	unsigned int num_dmem_regions;
38 	void *dmem_region_vaddr[MAX_UIO_MAPS];
39 	struct mutex alloc_lock;
40 	unsigned int refcnt;
41 };
42 
43 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
44 {
45 	struct uio_dmem_genirq_platdata *priv = info->priv;
46 	struct uio_mem *uiomem;
47 	int ret = 0;
48 	int dmem_region = priv->dmem_region_start;
49 
50 	uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
51 
52 	mutex_lock(&priv->alloc_lock);
53 	while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
54 		void *addr;
55 		if (!uiomem->size)
56 			break;
57 
58 		addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
59 				(dma_addr_t *)&uiomem->addr, GFP_KERNEL);
60 		if (!addr) {
61 			uiomem->addr = DMEM_MAP_ERROR;
62 		}
63 		priv->dmem_region_vaddr[dmem_region++] = addr;
64 		++uiomem;
65 	}
66 	priv->refcnt++;
67 
68 	mutex_unlock(&priv->alloc_lock);
69 	/* Wait until the Runtime PM code has woken up the device */
70 	pm_runtime_get_sync(&priv->pdev->dev);
71 	return ret;
72 }
73 
74 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
75 {
76 	struct uio_dmem_genirq_platdata *priv = info->priv;
77 	struct uio_mem *uiomem;
78 	int dmem_region = priv->dmem_region_start;
79 
80 	/* Tell the Runtime PM code that the device has become idle */
81 	pm_runtime_put_sync(&priv->pdev->dev);
82 
83 	uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
84 
85 	mutex_lock(&priv->alloc_lock);
86 
87 	priv->refcnt--;
88 	while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
89 		if (!uiomem->size)
90 			break;
91 		if (priv->dmem_region_vaddr[dmem_region]) {
92 			dma_free_coherent(&priv->pdev->dev, uiomem->size,
93 					priv->dmem_region_vaddr[dmem_region],
94 					uiomem->addr);
95 		}
96 		uiomem->addr = DMEM_MAP_ERROR;
97 		++dmem_region;
98 		++uiomem;
99 	}
100 
101 	mutex_unlock(&priv->alloc_lock);
102 	return 0;
103 }
104 
105 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
106 {
107 	struct uio_dmem_genirq_platdata *priv = dev_info->priv;
108 
109 	/* Just disable the interrupt in the interrupt controller, and
110 	 * remember the state so we can allow user space to enable it later.
111 	 */
112 
113 	if (!test_and_set_bit(0, &priv->flags))
114 		disable_irq_nosync(irq);
115 
116 	return IRQ_HANDLED;
117 }
118 
119 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
120 {
121 	struct uio_dmem_genirq_platdata *priv = dev_info->priv;
122 	unsigned long flags;
123 
124 	/* Allow user space to enable and disable the interrupt
125 	 * in the interrupt controller, but keep track of the
126 	 * state to prevent per-irq depth damage.
127 	 *
128 	 * Serialize this operation to support multiple tasks.
129 	 */
130 
131 	spin_lock_irqsave(&priv->lock, flags);
132 	if (irq_on) {
133 		if (test_and_clear_bit(0, &priv->flags))
134 			enable_irq(dev_info->irq);
135 		spin_unlock_irqrestore(&priv->lock, flags);
136 	} else {
137 		if (!test_and_set_bit(0, &priv->flags)) {
138 			spin_unlock_irqrestore(&priv->lock, flags);
139 			disable_irq(dev_info->irq);
140 		}
141 	}
142 
143 	return 0;
144 }
145 
146 static int uio_dmem_genirq_probe(struct platform_device *pdev)
147 {
148 	struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
149 	struct uio_info *uioinfo = &pdata->uioinfo;
150 	struct uio_dmem_genirq_platdata *priv;
151 	struct uio_mem *uiomem;
152 	int ret = -EINVAL;
153 	int i;
154 
155 	if (pdev->dev.of_node) {
156 		/* alloc uioinfo for one device */
157 		uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
158 		if (!uioinfo) {
159 			ret = -ENOMEM;
160 			dev_err(&pdev->dev, "unable to kmalloc\n");
161 			goto bad2;
162 		}
163 		uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
164 					       pdev->dev.of_node);
165 		uioinfo->version = "devicetree";
166 	}
167 
168 	if (!uioinfo || !uioinfo->name || !uioinfo->version) {
169 		dev_err(&pdev->dev, "missing platform_data\n");
170 		goto bad0;
171 	}
172 
173 	if (uioinfo->handler || uioinfo->irqcontrol ||
174 	    uioinfo->irq_flags & IRQF_SHARED) {
175 		dev_err(&pdev->dev, "interrupt configuration error\n");
176 		goto bad0;
177 	}
178 
179 	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
180 	if (!priv) {
181 		ret = -ENOMEM;
182 		dev_err(&pdev->dev, "unable to kmalloc\n");
183 		goto bad0;
184 	}
185 
186 	dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
187 
188 	priv->uioinfo = uioinfo;
189 	spin_lock_init(&priv->lock);
190 	priv->flags = 0; /* interrupt is enabled to begin with */
191 	priv->pdev = pdev;
192 	mutex_init(&priv->alloc_lock);
193 
194 	if (!uioinfo->irq) {
195 		/* Multiple IRQs are not supported */
196 		ret = platform_get_irq(pdev, 0);
197 		if (ret == -ENXIO && pdev->dev.of_node)
198 			ret = UIO_IRQ_NONE;
199 		else if (ret < 0)
200 			goto bad1;
201 		uioinfo->irq = ret;
202 	}
203 	uiomem = &uioinfo->mem[0];
204 
205 	for (i = 0; i < pdev->num_resources; ++i) {
206 		struct resource *r = &pdev->resource[i];
207 
208 		if (r->flags != IORESOURCE_MEM)
209 			continue;
210 
211 		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
212 			dev_warn(&pdev->dev, "device has more than "
213 					__stringify(MAX_UIO_MAPS)
214 					" I/O memory resources.\n");
215 			break;
216 		}
217 
218 		uiomem->memtype = UIO_MEM_PHYS;
219 		uiomem->addr = r->start;
220 		uiomem->size = resource_size(r);
221 		++uiomem;
222 	}
223 
224 	priv->dmem_region_start = uiomem - &uioinfo->mem[0];
225 	priv->num_dmem_regions = pdata->num_dynamic_regions;
226 
227 	for (i = 0; i < pdata->num_dynamic_regions; ++i) {
228 		if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
229 			dev_warn(&pdev->dev, "device has more than "
230 					__stringify(MAX_UIO_MAPS)
231 					" dynamic and fixed memory regions.\n");
232 			break;
233 		}
234 		uiomem->memtype = UIO_MEM_PHYS;
235 		uiomem->addr = DMEM_MAP_ERROR;
236 		uiomem->size = pdata->dynamic_region_sizes[i];
237 		++uiomem;
238 	}
239 
240 	while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
241 		uiomem->size = 0;
242 		++uiomem;
243 	}
244 
245 	/* This driver requires no hardware specific kernel code to handle
246 	 * interrupts. Instead, the interrupt handler simply disables the
247 	 * interrupt in the interrupt controller. User space is responsible
248 	 * for performing hardware specific acknowledge and re-enabling of
249 	 * the interrupt in the interrupt controller.
250 	 *
251 	 * Interrupt sharing is not supported.
252 	 */
253 
254 	uioinfo->handler = uio_dmem_genirq_handler;
255 	uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
256 	uioinfo->open = uio_dmem_genirq_open;
257 	uioinfo->release = uio_dmem_genirq_release;
258 	uioinfo->priv = priv;
259 
260 	/* Enable Runtime PM for this device:
261 	 * The device starts in suspended state to allow the hardware to be
262 	 * turned off by default. The Runtime PM bus code should power on the
263 	 * hardware and enable clocks at open().
264 	 */
265 	pm_runtime_enable(&pdev->dev);
266 
267 	ret = uio_register_device(&pdev->dev, priv->uioinfo);
268 	if (ret) {
269 		dev_err(&pdev->dev, "unable to register uio device\n");
270 		pm_runtime_disable(&pdev->dev);
271 		goto bad1;
272 	}
273 
274 	platform_set_drvdata(pdev, priv);
275 	return 0;
276  bad1:
277 	kfree(priv);
278  bad0:
279 	/* kfree uioinfo for OF */
280 	if (pdev->dev.of_node)
281 		kfree(uioinfo);
282  bad2:
283 	return ret;
284 }
285 
286 static int uio_dmem_genirq_remove(struct platform_device *pdev)
287 {
288 	struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
289 
290 	uio_unregister_device(priv->uioinfo);
291 	pm_runtime_disable(&pdev->dev);
292 
293 	priv->uioinfo->handler = NULL;
294 	priv->uioinfo->irqcontrol = NULL;
295 
296 	/* kfree uioinfo for OF */
297 	if (pdev->dev.of_node)
298 		kfree(priv->uioinfo);
299 
300 	kfree(priv);
301 	return 0;
302 }
303 
304 static int uio_dmem_genirq_runtime_nop(struct device *dev)
305 {
306 	/* Runtime PM callback shared between ->runtime_suspend()
307 	 * and ->runtime_resume(). Simply returns success.
308 	 *
309 	 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
310 	 * are used at open() and release() time. This allows the
311 	 * Runtime PM code to turn off power to the device while the
312 	 * device is unused, ie before open() and after release().
313 	 *
314 	 * This Runtime PM callback does not need to save or restore
315 	 * any registers since user space is responsbile for hardware
316 	 * register reinitialization after open().
317 	 */
318 	return 0;
319 }
320 
321 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
322 	.runtime_suspend = uio_dmem_genirq_runtime_nop,
323 	.runtime_resume = uio_dmem_genirq_runtime_nop,
324 };
325 
326 #ifdef CONFIG_OF
327 static const struct of_device_id uio_of_genirq_match[] = {
328 	{ /* empty for now */ },
329 };
330 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
331 #endif
332 
333 static struct platform_driver uio_dmem_genirq = {
334 	.probe = uio_dmem_genirq_probe,
335 	.remove = uio_dmem_genirq_remove,
336 	.driver = {
337 		.name = DRIVER_NAME,
338 		.pm = &uio_dmem_genirq_dev_pm_ops,
339 		.of_match_table = of_match_ptr(uio_of_genirq_match),
340 	},
341 };
342 
343 module_platform_driver(uio_dmem_genirq);
344 
345 MODULE_AUTHOR("Damian Hobson-Garcia");
346 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
347 MODULE_LICENSE("GPL v2");
348 MODULE_ALIAS("platform:" DRIVER_NAME);
349