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 #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_dmem_genirq"
30 #define DMEM_MAP_ERROR (~0)
31
32 struct uio_dmem_genirq_platdata {
33 struct uio_info *uioinfo;
34 spinlock_t lock;
35 unsigned long flags;
36 struct platform_device *pdev;
37 unsigned int dmem_region_start;
38 unsigned int num_dmem_regions;
39 void *dmem_region_vaddr[MAX_UIO_MAPS];
40 struct mutex alloc_lock;
41 unsigned int refcnt;
42 };
43
uio_dmem_genirq_open(struct uio_info * info,struct inode * inode)44 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
45 {
46 struct uio_dmem_genirq_platdata *priv = info->priv;
47 struct uio_mem *uiomem;
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 0;
72 }
73
uio_dmem_genirq_release(struct uio_info * info,struct inode * inode)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
uio_dmem_genirq_handler(int irq,struct uio_info * dev_info)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 spin_lock(&priv->lock);
114 if (!test_and_set_bit(0, &priv->flags))
115 disable_irq_nosync(irq);
116 spin_unlock(&priv->lock);
117
118 return IRQ_HANDLED;
119 }
120
uio_dmem_genirq_irqcontrol(struct uio_info * dev_info,s32 irq_on)121 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
122 {
123 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
124 unsigned long flags;
125
126 /* Allow user space to enable and disable the interrupt
127 * in the interrupt controller, but keep track of the
128 * state to prevent per-irq depth damage.
129 *
130 * Serialize this operation to support multiple tasks and concurrency
131 * with irq handler on SMP systems.
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_nosync(dev_info->irq);
141 }
142 spin_unlock_irqrestore(&priv->lock, flags);
143
144 return 0;
145 }
146
uio_dmem_genirq_pm_disable(void * data)147 static void uio_dmem_genirq_pm_disable(void *data)
148 {
149 struct device *dev = data;
150
151 pm_runtime_disable(dev);
152 }
153
uio_dmem_genirq_probe(struct platform_device * pdev)154 static int uio_dmem_genirq_probe(struct platform_device *pdev)
155 {
156 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
157 struct uio_info *uioinfo = &pdata->uioinfo;
158 struct uio_dmem_genirq_platdata *priv;
159 struct uio_mem *uiomem;
160 int ret = -EINVAL;
161 int i;
162
163 if (pdev->dev.of_node) {
164 /* alloc uioinfo for one device */
165 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo), GFP_KERNEL);
166 if (!uioinfo) {
167 dev_err(&pdev->dev, "unable to kmalloc\n");
168 return -ENOMEM;
169 }
170 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
171 pdev->dev.of_node);
172 uioinfo->version = "devicetree";
173 }
174
175 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
176 dev_err(&pdev->dev, "missing platform_data\n");
177 return -EINVAL;
178 }
179
180 if (uioinfo->handler || uioinfo->irqcontrol ||
181 uioinfo->irq_flags & IRQF_SHARED) {
182 dev_err(&pdev->dev, "interrupt configuration error\n");
183 return -EINVAL;
184 }
185
186 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
187 if (!priv) {
188 dev_err(&pdev->dev, "unable to kmalloc\n");
189 return -ENOMEM;
190 }
191
192 dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
193
194 priv->uioinfo = uioinfo;
195 spin_lock_init(&priv->lock);
196 priv->flags = 0; /* interrupt is enabled to begin with */
197 priv->pdev = pdev;
198 mutex_init(&priv->alloc_lock);
199
200 if (!uioinfo->irq) {
201 /* Multiple IRQs are not supported */
202 ret = platform_get_irq(pdev, 0);
203 if (ret == -ENXIO && pdev->dev.of_node)
204 ret = UIO_IRQ_NONE;
205 else if (ret < 0)
206 return ret;
207 uioinfo->irq = ret;
208 }
209
210 if (uioinfo->irq) {
211 struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq);
212
213 /*
214 * If a level interrupt, dont do lazy disable. Otherwise the
215 * irq will fire again since clearing of the actual cause, on
216 * device level, is done in userspace
217 * irqd_is_level_type() isn't used since isn't valid until
218 * irq is configured.
219 */
220 if (irq_data &&
221 irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) {
222 dev_dbg(&pdev->dev, "disable lazy unmask\n");
223 irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
224 }
225 }
226
227 uiomem = &uioinfo->mem[0];
228
229 for (i = 0; i < pdev->num_resources; ++i) {
230 struct resource *r = &pdev->resource[i];
231
232 if (r->flags != IORESOURCE_MEM)
233 continue;
234
235 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
236 dev_warn(&pdev->dev, "device has more than "
237 __stringify(MAX_UIO_MAPS)
238 " I/O memory resources.\n");
239 break;
240 }
241
242 uiomem->memtype = UIO_MEM_PHYS;
243 uiomem->addr = r->start;
244 uiomem->size = resource_size(r);
245 ++uiomem;
246 }
247
248 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
249 priv->num_dmem_regions = pdata->num_dynamic_regions;
250
251 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
252 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
253 dev_warn(&pdev->dev, "device has more than "
254 __stringify(MAX_UIO_MAPS)
255 " dynamic and fixed memory regions.\n");
256 break;
257 }
258 uiomem->memtype = UIO_MEM_PHYS;
259 uiomem->addr = DMEM_MAP_ERROR;
260 uiomem->size = pdata->dynamic_region_sizes[i];
261 ++uiomem;
262 }
263
264 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
265 uiomem->size = 0;
266 ++uiomem;
267 }
268
269 /* This driver requires no hardware specific kernel code to handle
270 * interrupts. Instead, the interrupt handler simply disables the
271 * interrupt in the interrupt controller. User space is responsible
272 * for performing hardware specific acknowledge and re-enabling of
273 * the interrupt in the interrupt controller.
274 *
275 * Interrupt sharing is not supported.
276 */
277
278 uioinfo->handler = uio_dmem_genirq_handler;
279 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
280 uioinfo->open = uio_dmem_genirq_open;
281 uioinfo->release = uio_dmem_genirq_release;
282 uioinfo->priv = priv;
283
284 /* Enable Runtime PM for this device:
285 * The device starts in suspended state to allow the hardware to be
286 * turned off by default. The Runtime PM bus code should power on the
287 * hardware and enable clocks at open().
288 */
289 pm_runtime_enable(&pdev->dev);
290
291 ret = devm_add_action_or_reset(&pdev->dev, uio_dmem_genirq_pm_disable, &pdev->dev);
292 if (ret)
293 return ret;
294
295 return devm_uio_register_device(&pdev->dev, priv->uioinfo);
296 }
297
uio_dmem_genirq_runtime_nop(struct device * dev)298 static int uio_dmem_genirq_runtime_nop(struct device *dev)
299 {
300 /* Runtime PM callback shared between ->runtime_suspend()
301 * and ->runtime_resume(). Simply returns success.
302 *
303 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
304 * are used at open() and release() time. This allows the
305 * Runtime PM code to turn off power to the device while the
306 * device is unused, ie before open() and after release().
307 *
308 * This Runtime PM callback does not need to save or restore
309 * any registers since user space is responsbile for hardware
310 * register reinitialization after open().
311 */
312 return 0;
313 }
314
315 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
316 .runtime_suspend = uio_dmem_genirq_runtime_nop,
317 .runtime_resume = uio_dmem_genirq_runtime_nop,
318 };
319
320 #ifdef CONFIG_OF
321 static const struct of_device_id uio_of_genirq_match[] = {
322 { /* empty for now */ },
323 };
324 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
325 #endif
326
327 static struct platform_driver uio_dmem_genirq = {
328 .probe = uio_dmem_genirq_probe,
329 .driver = {
330 .name = DRIVER_NAME,
331 .pm = &uio_dmem_genirq_dev_pm_ops,
332 .of_match_table = of_match_ptr(uio_of_genirq_match),
333 },
334 };
335
336 module_platform_driver(uio_dmem_genirq);
337
338 MODULE_AUTHOR("Damian Hobson-Garcia");
339 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
340 MODULE_LICENSE("GPL v2");
341 MODULE_ALIAS("platform:" DRIVER_NAME);
342