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;
48 int dmem_region = priv->dmem_region_start;
50 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
52 mutex_lock(&priv->alloc_lock);
53 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
58 addr = dma_alloc_coherent(&priv->pdev->dev, uiomem->size,
59 (dma_addr_t *)&uiomem->addr, GFP_KERNEL);
61 uiomem->addr = DMEM_MAP_ERROR;
63 priv->dmem_region_vaddr[dmem_region++] = addr;
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);
74 static int uio_dmem_genirq_release(struct uio_info *info, struct inode *inode)
76 struct uio_dmem_genirq_platdata *priv = info->priv;
77 struct uio_mem *uiomem;
78 int dmem_region = priv->dmem_region_start;
80 /* Tell the Runtime PM code that the device has become idle */
81 pm_runtime_put_sync(&priv->pdev->dev);
83 uiomem = &priv->uioinfo->mem[priv->dmem_region_start];
85 mutex_lock(&priv->alloc_lock);
88 while (!priv->refcnt && uiomem < &priv->uioinfo->mem[MAX_UIO_MAPS]) {
91 if (priv->dmem_region_vaddr[dmem_region]) {
92 dma_free_coherent(&priv->pdev->dev, uiomem->size,
93 priv->dmem_region_vaddr[dmem_region],
96 uiomem->addr = DMEM_MAP_ERROR;
101 mutex_unlock(&priv->alloc_lock);
105 static irqreturn_t uio_dmem_genirq_handler(int irq, struct uio_info *dev_info)
107 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
109 /* Just disable the interrupt in the interrupt controller, and
110 * remember the state so we can allow user space to enable it later.
113 if (!test_and_set_bit(0, &priv->flags))
114 disable_irq_nosync(irq);
119 static int uio_dmem_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
121 struct uio_dmem_genirq_platdata *priv = dev_info->priv;
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.
128 * Serialize this operation to support multiple tasks.
131 spin_lock_irqsave(&priv->lock, flags);
133 if (test_and_clear_bit(0, &priv->flags))
134 enable_irq(dev_info->irq);
136 if (!test_and_set_bit(0, &priv->flags))
137 disable_irq(dev_info->irq);
139 spin_unlock_irqrestore(&priv->lock, flags);
144 static int uio_dmem_genirq_probe(struct platform_device *pdev)
146 struct uio_dmem_genirq_pdata *pdata = dev_get_platdata(&pdev->dev);
147 struct uio_info *uioinfo = &pdata->uioinfo;
148 struct uio_dmem_genirq_platdata *priv;
149 struct uio_mem *uiomem;
153 if (pdev->dev.of_node) {
156 /* alloc uioinfo for one device */
157 uioinfo = kzalloc(sizeof(*uioinfo), GFP_KERNEL);
160 dev_err(&pdev->dev, "unable to kmalloc\n");
163 uioinfo->name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "%pOFn",
165 uioinfo->version = "devicetree";
167 /* Multiple IRQs are not supported */
168 irq = platform_get_irq(pdev, 0);
170 uioinfo->irq = UIO_IRQ_NONE;
175 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
176 dev_err(&pdev->dev, "missing platform_data\n");
180 if (uioinfo->handler || uioinfo->irqcontrol ||
181 uioinfo->irq_flags & IRQF_SHARED) {
182 dev_err(&pdev->dev, "interrupt configuration error\n");
186 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
189 dev_err(&pdev->dev, "unable to kmalloc\n");
193 dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(32));
195 priv->uioinfo = uioinfo;
196 spin_lock_init(&priv->lock);
197 priv->flags = 0; /* interrupt is enabled to begin with */
199 mutex_init(&priv->alloc_lock);
202 ret = platform_get_irq(pdev, 0);
204 dev_err(&pdev->dev, "failed to get IRQ\n");
209 uiomem = &uioinfo->mem[0];
211 for (i = 0; i < pdev->num_resources; ++i) {
212 struct resource *r = &pdev->resource[i];
214 if (r->flags != IORESOURCE_MEM)
217 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
218 dev_warn(&pdev->dev, "device has more than "
219 __stringify(MAX_UIO_MAPS)
220 " I/O memory resources.\n");
224 uiomem->memtype = UIO_MEM_PHYS;
225 uiomem->addr = r->start;
226 uiomem->size = resource_size(r);
230 priv->dmem_region_start = uiomem - &uioinfo->mem[0];
231 priv->num_dmem_regions = pdata->num_dynamic_regions;
233 for (i = 0; i < pdata->num_dynamic_regions; ++i) {
234 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
235 dev_warn(&pdev->dev, "device has more than "
236 __stringify(MAX_UIO_MAPS)
237 " dynamic and fixed memory regions.\n");
240 uiomem->memtype = UIO_MEM_PHYS;
241 uiomem->addr = DMEM_MAP_ERROR;
242 uiomem->size = pdata->dynamic_region_sizes[i];
246 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
251 /* This driver requires no hardware specific kernel code to handle
252 * interrupts. Instead, the interrupt handler simply disables the
253 * interrupt in the interrupt controller. User space is responsible
254 * for performing hardware specific acknowledge and re-enabling of
255 * the interrupt in the interrupt controller.
257 * Interrupt sharing is not supported.
260 uioinfo->handler = uio_dmem_genirq_handler;
261 uioinfo->irqcontrol = uio_dmem_genirq_irqcontrol;
262 uioinfo->open = uio_dmem_genirq_open;
263 uioinfo->release = uio_dmem_genirq_release;
264 uioinfo->priv = priv;
266 /* Enable Runtime PM for this device:
267 * The device starts in suspended state to allow the hardware to be
268 * turned off by default. The Runtime PM bus code should power on the
269 * hardware and enable clocks at open().
271 pm_runtime_enable(&pdev->dev);
273 ret = uio_register_device(&pdev->dev, priv->uioinfo);
275 dev_err(&pdev->dev, "unable to register uio device\n");
276 pm_runtime_disable(&pdev->dev);
280 platform_set_drvdata(pdev, priv);
285 /* kfree uioinfo for OF */
286 if (pdev->dev.of_node)
292 static int uio_dmem_genirq_remove(struct platform_device *pdev)
294 struct uio_dmem_genirq_platdata *priv = platform_get_drvdata(pdev);
296 uio_unregister_device(priv->uioinfo);
297 pm_runtime_disable(&pdev->dev);
299 priv->uioinfo->handler = NULL;
300 priv->uioinfo->irqcontrol = NULL;
302 /* kfree uioinfo for OF */
303 if (pdev->dev.of_node)
304 kfree(priv->uioinfo);
310 static int uio_dmem_genirq_runtime_nop(struct device *dev)
312 /* Runtime PM callback shared between ->runtime_suspend()
313 * and ->runtime_resume(). Simply returns success.
315 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
316 * are used at open() and release() time. This allows the
317 * Runtime PM code to turn off power to the device while the
318 * device is unused, ie before open() and after release().
320 * This Runtime PM callback does not need to save or restore
321 * any registers since user space is responsbile for hardware
322 * register reinitialization after open().
327 static const struct dev_pm_ops uio_dmem_genirq_dev_pm_ops = {
328 .runtime_suspend = uio_dmem_genirq_runtime_nop,
329 .runtime_resume = uio_dmem_genirq_runtime_nop,
333 static const struct of_device_id uio_of_genirq_match[] = {
334 { /* empty for now */ },
336 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
339 static struct platform_driver uio_dmem_genirq = {
340 .probe = uio_dmem_genirq_probe,
341 .remove = uio_dmem_genirq_remove,
344 .pm = &uio_dmem_genirq_dev_pm_ops,
345 .of_match_table = of_match_ptr(uio_of_genirq_match),
349 module_platform_driver(uio_dmem_genirq);
351 MODULE_AUTHOR("Damian Hobson-Garcia");
352 MODULE_DESCRIPTION("Userspace I/O platform driver with dynamic memory.");
353 MODULE_LICENSE("GPL v2");
354 MODULE_ALIAS("platform:" DRIVER_NAME);