1 // SPDX-License-Identifier: GPL-2.0-only
3 * drivers/uio/uio_dmem_genirq.c
5 * Userspace I/O platform driver with generic IRQ handling code.
7 * Copyright (C) 2012 Damian Hobson-Garcia
9 * Based on uio_pdrv_genirq.c by Magnus Damm
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>
25 #include <linux/of_platform.h>
26 #include <linux/of_address.h>
28 #define DRIVER_NAME "uio_dmem_genirq"
29 #define DMEM_MAP_ERROR (~0)
31 struct uio_dmem_genirq_platdata {
32 struct uio_info *uioinfo;
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;
43 static int uio_dmem_genirq_open(struct uio_info *info, struct inode *inode)
45 struct uio_dmem_genirq_platdata *priv = info->priv;
46 struct uio_mem *uiomem;
47 int dmem_region = priv->dmem_region_start;
49 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
51 mutex_lock(&priv->alloc_lock);
52 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
57 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
58 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
60 uiomem->addr = DMEM_MAP_ERROR;
62 priv->dmem_region_vaddr[dmem_region++] = addr;
67 mutex_unlock(&priv->alloc_lock);
68 /* Wait until the Runtime PM code has woken up the device */
69 pm_runtime_get_sync(&priv->pdev->dev);
73 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
75 struct uio_dmem_genirq_platdata *priv = info->priv;
76 struct uio_mem *uiomem;
77 int dmem_region = priv->dmem_region_start;
79 /* Tell the Runtime PM code that the device has become idle */
80 pm_runtime_put_sync(&priv->pdev->dev);
82 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
84 mutex_lock(&priv->alloc_lock);
87 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
90 if (priv->dmem_region_vaddr[dmem_region]) {
91 dma_free_coherent(&priv->pdev->dev, uiomem->size,
92 priv->dmem_region_vaddr[dmem_region],
95 uiomem->addr = DMEM_MAP_ERROR;
100 mutex_unlock(&priv->alloc_lock);
104 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
106 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
108 /* Just disable the interrupt in the interrupt controller, and
109 * remember the state so we can allow user space to enable it later.
112 if (!test_and_set_bit(0, &priv->flags))
113 disable_irq_nosync(irq);
118 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
120 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
123 /* Allow user space to enable and disable the interrupt
124 * in the interrupt controller, but keep track of the
125 * state to prevent per-irq depth damage.
127 * Serialize this operation to support multiple tasks.
130 spin_lock_irqsave(&priv->lock, flags);
132 if (test_and_clear_bit(0, &priv->flags))
133 enable_irq(dev_info->irq);
134 spin_unlock_irqrestore(&priv->lock, flags);
136 if (!test_and_set_bit(0, &priv->flags)) {
137 spin_unlock_irqrestore(&priv->lock, flags);
138 disable_irq(dev_info->irq);
145 static int uio_dmem_genirq_probe(struct platform_device *pdev)
147 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
148 struct uio_info *uioinfo = &pdata->uioinfo;
149 struct uio_dmem_genirq_platdata *priv;
150 struct uio_mem *uiomem;
154 if (pdev->dev.of_node) {
155 /* alloc uioinfo for one device */
156 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
159 dev_err(&pdev->dev, "unable to kmalloc\n");
162 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
164 uioinfo->version = "devicetree";
167 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
168 dev_err(&pdev->dev, "missing platform_data\n");
172 if (uioinfo->handler || uioinfo->irqcontrol ||
173 uioinfo->irq_flags & IRQF_SHARED) {
174 dev_err(&pdev->dev, "interrupt configuration error\n");
178 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
181 dev_err(&pdev->dev, "unable to kmalloc\n");
185 dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
187 priv->uioinfo = uioinfo;
188 spin_lock_init(&priv->lock);
189 priv->flags = 0; /* interrupt is enabled to begin with */
191 mutex_init(&priv->alloc_lock);
194 /* Multiple IRQs are not supported */
195 ret = platform_get_irq(pdev, 0);
196 if (ret == -ENXIO && pdev->dev.of_node)
202 uiomem = &uioinfo->mem[0];
204 for (i = 0; i < pdev->num_resources; ++i) {
205 struct resource *r = &pdev->resource[i];
207 if (r->flags != IORESOURCE_MEM)
210 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
211 dev_warn(&pdev->dev, "device has more than "
212 __stringify(MAX_UIO_MAPS)
213 " I/O memory resources.\n");
217 uiomem->memtype = UIO_MEM_PHYS;
218 uiomem->addr = r->start;
219 uiomem->size = resource_size(r);
223 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
224 priv->num_dmem_regions = pdata->num_dynamic_regions;
226 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
227 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
228 dev_warn(&pdev->dev, "device has more than "
229 __stringify(MAX_UIO_MAPS)
230 " dynamic and fixed memory regions.\n");
233 uiomem->memtype = UIO_MEM_PHYS;
234 uiomem->addr = DMEM_MAP_ERROR;
235 uiomem->size = pdata->dynamic_region_sizes[i];
239 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
244 /* This driver requires no hardware specific kernel code to handle
245 * interrupts. Instead, the interrupt handler simply disables the
246 * interrupt in the interrupt controller. User space is responsible
247 * for performing hardware specific acknowledge and re-enabling of
248 * the interrupt in the interrupt controller.
250 * Interrupt sharing is not supported.
253 uioinfo->handler = uio_dmem_genirq_handler;
254 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
255 uioinfo->open = uio_dmem_genirq_open;
256 uioinfo->release = uio_dmem_genirq_release;
257 uioinfo->priv = priv;
259 /* Enable Runtime PM for this device:
260 * The device starts in suspended state to allow the hardware to be
261 * turned off by default. The Runtime PM bus code should power on the
262 * hardware and enable clocks at open().
264 pm_runtime_enable(&pdev->dev);
266 ret = uio_register_device(&pdev->dev, priv->uioinfo);
268 dev_err(&pdev->dev, "unable to register uio device\n");
269 pm_runtime_disable(&pdev->dev);
273 platform_set_drvdata(pdev, priv);
278 /* kfree uioinfo for OF */
279 if (pdev->dev.of_node)
285 static int uio_dmem_genirq_remove(struct platform_device *pdev)
287 struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
289 uio_unregister_device(priv->uioinfo);
290 pm_runtime_disable(&pdev->dev);
292 priv->uioinfo->handler = NULL;
293 priv->uioinfo->irqcontrol = NULL;
295 /* kfree uioinfo for OF */
296 if (pdev->dev.of_node)
297 kfree(priv->uioinfo);
303 static int uio_dmem_genirq_runtime_nop(struct device *dev)
305 /* Runtime PM callback shared between ->runtime_suspend()
306 * and ->runtime_resume(). Simply returns success.
308 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
309 * are used at open() and release() time. This allows the
310 * Runtime PM code to turn off power to the device while the
311 * device is unused, ie before open() and after release().
313 * This Runtime PM callback does not need to save or restore
314 * any registers since user space is responsbile for hardware
315 * register reinitialization after open().
320 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
321 .runtime_suspend = uio_dmem_genirq_runtime_nop,
322 .runtime_resume = uio_dmem_genirq_runtime_nop,
326 static const struct of_device_id uio_of_genirq_match[] = {
327 { /* empty for now */ },
329 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
332 static struct platform_driver uio_dmem_genirq = {
333 .probe = uio_dmem_genirq_probe,
334 .remove = uio_dmem_genirq_remove,
337 .pm = &uio_dmem_genirq_dev_pm_ops,
338 .of_match_table = of_match_ptr(uio_of_genirq_match),
342 module_platform_driver(uio_dmem_genirq);
344 MODULE_AUTHOR("Damian Hobson-Garcia");
345 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
346 MODULE_LICENSE("GPL v2");
347 MODULE_ALIAS("platform:" DRIVER_NAME);