2 * drivers/uio/uio_pdrv_genirq.c
4 * Userspace I/O platform driver with generic IRQ handling code.
6 * Copyright (C) 2008 Magnus Damm
8 * Based on uio_pdrv.c by Uwe Kleine-Koenig,
9 * Copyright (C) 2008 by Digi International Inc.
10 * All rights reserved.
12 * This program is free software; you can redistribute it and/or modify it
13 * under the terms of the GNU General Public License version 2 as published by
14 * the Free Software Foundation.
17 #include <linux/platform_device.h>
18 #include <linux/uio_driver.h>
19 #include <linux/spinlock.h>
20 #include <linux/bitops.h>
21 #include <linux/module.h>
22 #include <linux/interrupt.h>
23 #include <linux/stringify.h>
24 #include <linux/pm_runtime.h>
25 #include <linux/slab.h>
28 #include <linux/of_platform.h>
29 #include <linux/of_address.h>
31 #define DRIVER_NAME "uio_pdrv_genirq"
33 struct uio_pdrv_genirq_platdata {
34 struct uio_info *uioinfo;
37 struct platform_device *pdev;
40 /* Bits in uio_pdrv_genirq_platdata.flags */
45 static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode)
47 struct uio_pdrv_genirq_platdata *priv = info->priv;
49 /* Wait until the Runtime PM code has woken up the device */
50 pm_runtime_get_sync(&priv->pdev->dev);
54 static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode)
56 struct uio_pdrv_genirq_platdata *priv = info->priv;
58 /* Tell the Runtime PM code that the device has become idle */
59 pm_runtime_put_sync(&priv->pdev->dev);
63 static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info)
65 struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
67 /* Just disable the interrupt in the interrupt controller, and
68 * remember the state so we can allow user space to enable it later.
71 spin_lock(&priv->lock);
72 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
73 disable_irq_nosync(irq);
74 spin_unlock(&priv->lock);
79 static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on)
81 struct uio_pdrv_genirq_platdata *priv = dev_info->priv;
84 /* Allow user space to enable and disable the interrupt
85 * in the interrupt controller, but keep track of the
86 * state to prevent per-irq depth damage.
88 * Serialize this operation to support multiple tasks and concurrency
89 * with irq handler on SMP systems.
92 spin_lock_irqsave(&priv->lock, flags);
94 if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags))
95 enable_irq(dev_info->irq);
97 if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags))
98 disable_irq_nosync(dev_info->irq);
100 spin_unlock_irqrestore(&priv->lock, flags);
105 static int uio_pdrv_genirq_probe(struct platform_device *pdev)
107 struct uio_info *uioinfo = dev_get_platdata(&pdev->dev);
108 struct uio_pdrv_genirq_platdata *priv;
109 struct uio_mem *uiomem;
113 if (pdev->dev.of_node) {
114 /* alloc uioinfo for one device */
115 uioinfo = devm_kzalloc(&pdev->dev, sizeof(*uioinfo),
118 dev_err(&pdev->dev, "unable to kmalloc\n");
121 uioinfo->name = pdev->dev.of_node->name;
122 uioinfo->version = "devicetree";
123 /* Multiple IRQs are not supported */
126 if (!uioinfo || !uioinfo->name || !uioinfo->version) {
127 dev_err(&pdev->dev, "missing platform_data\n");
131 if (uioinfo->handler || uioinfo->irqcontrol ||
132 uioinfo->irq_flags & IRQF_SHARED) {
133 dev_err(&pdev->dev, "interrupt configuration error\n");
137 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
139 dev_err(&pdev->dev, "unable to kmalloc\n");
143 priv->uioinfo = uioinfo;
144 spin_lock_init(&priv->lock);
145 priv->flags = 0; /* interrupt is enabled to begin with */
149 ret = platform_get_irq(pdev, 0);
151 if (ret == -ENXIO && pdev->dev.of_node)
152 uioinfo->irq = UIO_IRQ_NONE;
154 dev_err(&pdev->dev, "failed to get IRQ\n");
159 uiomem = &uioinfo->mem[0];
161 for (i = 0; i < pdev->num_resources; ++i) {
162 struct resource *r = &pdev->resource[i];
164 if (r->flags != IORESOURCE_MEM)
167 if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) {
168 dev_warn(&pdev->dev, "device has more than "
169 __stringify(MAX_UIO_MAPS)
170 " I/O memory resources.\n");
174 uiomem->memtype = UIO_MEM_PHYS;
175 uiomem->addr = r->start;
176 uiomem->size = resource_size(r);
177 uiomem->name = r->name;
181 while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) {
186 /* This driver requires no hardware specific kernel code to handle
187 * interrupts. Instead, the interrupt handler simply disables the
188 * interrupt in the interrupt controller. User space is responsible
189 * for performing hardware specific acknowledge and re-enabling of
190 * the interrupt in the interrupt controller.
192 * Interrupt sharing is not supported.
195 uioinfo->handler = uio_pdrv_genirq_handler;
196 uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol;
197 uioinfo->open = uio_pdrv_genirq_open;
198 uioinfo->release = uio_pdrv_genirq_release;
199 uioinfo->priv = priv;
201 /* Enable Runtime PM for this device:
202 * The device starts in suspended state to allow the hardware to be
203 * turned off by default. The Runtime PM bus code should power on the
204 * hardware and enable clocks at open().
206 pm_runtime_enable(&pdev->dev);
208 ret = uio_register_device(&pdev->dev, priv->uioinfo);
210 dev_err(&pdev->dev, "unable to register uio device\n");
211 pm_runtime_disable(&pdev->dev);
215 platform_set_drvdata(pdev, priv);
219 static int uio_pdrv_genirq_remove(struct platform_device *pdev)
221 struct uio_pdrv_genirq_platdata *priv = platform_get_drvdata(pdev);
223 uio_unregister_device(priv->uioinfo);
224 pm_runtime_disable(&pdev->dev);
226 priv->uioinfo->handler = NULL;
227 priv->uioinfo->irqcontrol = NULL;
232 static int uio_pdrv_genirq_runtime_nop(struct device *dev)
234 /* Runtime PM callback shared between ->runtime_suspend()
235 * and ->runtime_resume(). Simply returns success.
237 * In this driver pm_runtime_get_sync() and pm_runtime_put_sync()
238 * are used at open() and release() time. This allows the
239 * Runtime PM code to turn off power to the device while the
240 * device is unused, ie before open() and after release().
242 * This Runtime PM callback does not need to save or restore
243 * any registers since user space is responsbile for hardware
244 * register reinitialization after open().
249 static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = {
250 .runtime_suspend = uio_pdrv_genirq_runtime_nop,
251 .runtime_resume = uio_pdrv_genirq_runtime_nop,
255 static struct of_device_id uio_of_genirq_match[] = {
256 { /* This is filled with module_parm */ },
259 MODULE_DEVICE_TABLE(of, uio_of_genirq_match);
260 module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0);
261 MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio");
264 static struct platform_driver uio_pdrv_genirq = {
265 .probe = uio_pdrv_genirq_probe,
266 .remove = uio_pdrv_genirq_remove,
269 .pm = &uio_pdrv_genirq_dev_pm_ops,
270 .of_match_table = of_match_ptr(uio_of_genirq_match),
274 module_platform_driver(uio_pdrv_genirq);
276 MODULE_AUTHOR("Magnus Damm");
277 MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling");
278 MODULE_LICENSE("GPL v2");
279 MODULE_ALIAS("platform:" DRIVER_NAME);