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 struct mutex alloc_lock;
40 unsigned int refcnt;
41 };
42
43 /* Bits in uio_dmem_genirq_platdata.flags */
44 enum {
45 UIO_IRQ_DISABLED = 0,
46 };
47
uio_dmem_genirq_open(struct uio_info * info,struct inode * inode)48 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
49 {
50 struct uio_dmem_genirq_platdata *priv = info->priv;
51 struct uio_mem *uiomem;
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 &uiomem->dma_addr, GFP_KERNEL);
63 uiomem->addr = addr ? (uintptr_t) addr : DMEM_MAP_ERROR;
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
79 /* Tell the Runtime PM code that the device has become idle */
80 pm_runtime_put_sync(&priv->pdev->dev);
81
82 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
83
84 mutex_lock(&priv->alloc_lock);
85
86 priv->refcnt--;
87 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
88 if (!uiomem->size)
89 break;
90 if (uiomem->addr) {
91 dma_free_coherent(uiomem->dma_device, uiomem->size,
92 (void *) (uintptr_t) uiomem->addr,
93 uiomem->dma_addr);
94 }
95 uiomem->addr = DMEM_MAP_ERROR;
96 ++uiomem;
97 }
98
99 mutex_unlock(&priv->alloc_lock);
100 return 0;
101 }
102
uio_dmem_genirq_handler(int irq,struct uio_info * dev_info)103 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
104 {
105 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
106
107 /* Just disable the interrupt in the interrupt controller, and
108 * remember the state so we can allow user space to enable it later.
109 */
110
111 spin_lock(&priv->lock);
112 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
113 disable_irq_nosync(irq);
114 spin_unlock(&priv->lock);
115
116 return IRQ_HANDLED;
117 }
118
uio_dmem_genirq_irqcontrol(struct uio_info * dev_info,s32 irq_on)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 and concurrency
129 * with irq handler on SMP systems.
130 */
131
132 spin_lock_irqsave(&priv->lock, flags);
133 if (irq_on) {
134 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
135 enable_irq(dev_info->irq);
136 } else {
137 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
138 disable_irq_nosync(dev_info->irq);
139 }
140 spin_unlock_irqrestore(&priv->lock, flags);
141
142 return 0;
143 }
144
uio_dmem_genirq_pm_disable(void * data)145 static void uio_dmem_genirq_pm_disable(void *data)
146 {
147 struct device *dev = data;
148
149 pm_runtime_disable(dev);
150 }
151
uio_dmem_genirq_probe(struct platform_device * pdev)152 static int uio_dmem_genirq_probe(struct platform_device *pdev)
153 {
154 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
155 struct uio_info *uioinfo = &pdata->uioinfo;
156 struct uio_dmem_genirq_platdata *priv;
157 struct uio_mem *uiomem;
158 int ret = -EINVAL;
159 int i;
160
161 if (pdev->dev.of_node) {
162 /* alloc uioinfo for one device */
163 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo), GFP_KERNEL);
164 if (!uioinfo) {
165 dev_err(&pdev->dev, "unable to kmalloc\n");
166 return -ENOMEM;
167 }
168 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
169 pdev->dev.of_node);
170 uioinfo->version = "devicetree";
171 }
172
173 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
174 dev_err(&pdev->dev, "missing platform_data\n");
175 return -EINVAL;
176 }
177
178 if (uioinfo->handler || uioinfo->irqcontrol ||
179 uioinfo->irq_flags & IRQF_SHARED) {
180 dev_err(&pdev->dev, "interrupt configuration error\n");
181 return -EINVAL;
182 }
183
184 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
185 if (!priv) {
186 dev_err(&pdev->dev, "unable to kmalloc\n");
187 return -ENOMEM;
188 }
189
190 ret = dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
191 if (ret) {
192 dev_err(&pdev->dev, "DMA enable failed\n");
193 return ret;
194 }
195
196 priv->uioinfo = uioinfo;
197 spin_lock_init(&priv->lock);
198 priv->flags = 0; /* interrupt is enabled to begin with */
199 priv->pdev = pdev;
200 mutex_init(&priv->alloc_lock);
201
202 if (!uioinfo->irq) {
203 /* Multiple IRQs are not supported */
204 ret = platform_get_irq(pdev, 0);
205 if (ret == -ENXIO && pdev->dev.of_node)
206 ret = UIO_IRQ_NONE;
207 else if (ret < 0)
208 return ret;
209 uioinfo->irq = ret;
210 }
211
212 if (uioinfo->irq) {
213 struct irq_data *irq_data = irq_get_irq_data(uioinfo->irq);
214
215 /*
216 * If a level interrupt, dont do lazy disable. Otherwise the
217 * irq will fire again since clearing of the actual cause, on
218 * device level, is done in userspace
219 * irqd_is_level_type() isn't used since isn't valid until
220 * irq is configured.
221 */
222 if (irq_data &&
223 irqd_get_trigger_type(irq_data) & IRQ_TYPE_LEVEL_MASK) {
224 dev_dbg(&pdev->dev, "disable lazy unmask\n");
225 irq_set_status_flags(uioinfo->irq, IRQ_DISABLE_UNLAZY);
226 }
227 }
228
229 uiomem = &uioinfo->mem[0];
230
231 for (i = 0; i < pdev->num_resources; ++i) {
232 struct resource *r = &pdev->resource[i];
233
234 if (r->flags != IORESOURCE_MEM)
235 continue;
236
237 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
238 dev_warn(&pdev->dev, "device has more than "
239 __stringify(MAX_UIO_MAPS)
240 " I/O memory resources.\n");
241 break;
242 }
243
244 uiomem->memtype = UIO_MEM_PHYS;
245 uiomem->addr = r->start;
246 uiomem->size = resource_size(r);
247 ++uiomem;
248 }
249
250 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
251 priv->num_dmem_regions = pdata->num_dynamic_regions;
252
253 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
254 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
255 dev_warn(&pdev->dev, "device has more than "
256 __stringify(MAX_UIO_MAPS)
257 " dynamic and fixed memory regions.\n");
258 break;
259 }
260 uiomem->memtype = UIO_MEM_DMA_COHERENT;
261 uiomem->dma_device = &pdev->dev;
262 uiomem->addr = DMEM_MAP_ERROR;
263 uiomem->size = pdata->dynamic_region_sizes[i];
264 ++uiomem;
265 }
266
267 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
268 uiomem->size = 0;
269 ++uiomem;
270 }
271
272 /* This driver requires no hardware specific kernel code to handle
273 * interrupts. Instead, the interrupt handler simply disables the
274 * interrupt in the interrupt controller. User space is responsible
275 * for performing hardware specific acknowledge and re-enabling of
276 * the interrupt in the interrupt controller.
277 *
278 * Interrupt sharing is not supported.
279 */
280
281 uioinfo->handler = uio_dmem_genirq_handler;
282 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
283 uioinfo->open = uio_dmem_genirq_open;
284 uioinfo->release = uio_dmem_genirq_release;
285 uioinfo->priv = priv;
286
287 /* Enable Runtime PM for this device:
288 * The device starts in suspended state to allow the hardware to be
289 * turned off by default. The Runtime PM bus code should power on the
290 * hardware and enable clocks at open().
291 */
292 pm_runtime_enable(&pdev->dev);
293
294 ret = devm_add_action_or_reset(&pdev->dev, uio_dmem_genirq_pm_disable, &pdev->dev);
295 if (ret)
296 return ret;
297
298 return devm_uio_register_device(&pdev->dev, priv->uioinfo);
299 }
300
uio_dmem_genirq_runtime_nop(struct device * dev)301 static int uio_dmem_genirq_runtime_nop(struct device *dev)
302 {
303 /* Runtime PM callback shared between ->runtime_suspend()
304 * and ->runtime_resume(). Simply returns success.
305 *
306 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
307 * are used at open() and release() time. This allows the
308 * Runtime PM code to turn off power to the device while the
309 * device is unused, ie before open() and after release().
310 *
311 * This Runtime PM callback does not need to save or restore
312 * any registers since user space is responsbile for hardware
313 * register reinitialization after open().
314 */
315 return 0;
316 }
317
318 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
319 .runtime_suspend = uio_dmem_genirq_runtime_nop,
320 .runtime_resume = uio_dmem_genirq_runtime_nop,
321 };
322
323 #ifdef CONFIG_OF
324 static const struct of_device_id uio_of_genirq_match[] = {
325 { /* empty for now */ },
326 };
327 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
328 #endif
329
330 static struct platform_driver uio_dmem_genirq = {
331 .probe = uio_dmem_genirq_probe,
332 .driver = {
333 .name = DRIVER_NAME,
334 .pm = &uio_dmem_genirq_dev_pm_ops,
335 .of_match_table = of_match_ptr(uio_of_genirq_match),
336 },
337 };
338
339 module_platform_driver(uio_dmem_genirq);
340
341 MODULE_AUTHOR("Damian Hobson-Garcia");
342 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
343 MODULE_LICENSE("GPL v2");
344 MODULE_ALIAS("platform:" DRIVER_NAME);
345