1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * drivers/uio/uio_pdrv_genirq.c |
4 | * |
5 | * Userspace I/O platform driver with generic IRQ handling code. |
6 | * |
7 | * Copyright (C) 2008 Magnus Damm |
8 | * |
9 | * Based on uio_pdrv.c by Uwe Kleine-Koenig, |
10 | * Copyright (C) 2008 by Digi International Inc. |
11 | * All rights reserved. |
12 | */ |
13 | |
14 | #include <linux/platform_device.h> |
15 | #include <linux/uio_driver.h> |
16 | #include <linux/spinlock.h> |
17 | #include <linux/bitops.h> |
18 | #include <linux/module.h> |
19 | #include <linux/interrupt.h> |
20 | #include <linux/stringify.h> |
21 | #include <linux/pm_runtime.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_pdrv_genirq" |
30 | |
31 | struct uio_pdrv_genirq_platdata { |
32 | struct uio_info *uioinfo; |
33 | spinlock_t lock; |
34 | unsigned long flags; |
35 | struct platform_device *pdev; |
36 | }; |
37 | |
38 | /* Bits in uio_pdrv_genirq_platdata.flags */ |
39 | enum { |
40 | UIO_IRQ_DISABLED = 0, |
41 | }; |
42 | |
43 | static int uio_pdrv_genirq_open(struct uio_info *info, struct inode *inode) |
44 | { |
45 | struct uio_pdrv_genirq_platdata *priv = info->priv; |
46 | |
47 | /* Wait until the Runtime PM code has woken up the device */ |
48 | pm_runtime_get_sync(dev: &priv->pdev->dev); |
49 | return 0; |
50 | } |
51 | |
52 | static int uio_pdrv_genirq_release(struct uio_info *info, struct inode *inode) |
53 | { |
54 | struct uio_pdrv_genirq_platdata *priv = info->priv; |
55 | |
56 | /* Tell the Runtime PM code that the device has become idle */ |
57 | pm_runtime_put_sync(dev: &priv->pdev->dev); |
58 | return 0; |
59 | } |
60 | |
61 | static irqreturn_t uio_pdrv_genirq_handler(int irq, struct uio_info *dev_info) |
62 | { |
63 | struct uio_pdrv_genirq_platdata *priv = dev_info->priv; |
64 | |
65 | /* Just disable the interrupt in the interrupt controller, and |
66 | * remember the state so we can allow user space to enable it later. |
67 | */ |
68 | |
69 | spin_lock(lock: &priv->lock); |
70 | if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags)) |
71 | disable_irq_nosync(irq); |
72 | spin_unlock(lock: &priv->lock); |
73 | |
74 | return IRQ_HANDLED; |
75 | } |
76 | |
77 | static int uio_pdrv_genirq_irqcontrol(struct uio_info *dev_info, s32 irq_on) |
78 | { |
79 | struct uio_pdrv_genirq_platdata *priv = dev_info->priv; |
80 | unsigned long flags; |
81 | |
82 | /* Allow user space to enable and disable the interrupt |
83 | * in the interrupt controller, but keep track of the |
84 | * state to prevent per-irq depth damage. |
85 | * |
86 | * Serialize this operation to support multiple tasks and concurrency |
87 | * with irq handler on SMP systems. |
88 | */ |
89 | |
90 | spin_lock_irqsave(&priv->lock, flags); |
91 | if (irq_on) { |
92 | if (__test_and_clear_bit(UIO_IRQ_DISABLED, &priv->flags)) |
93 | enable_irq(irq: dev_info->irq); |
94 | } else { |
95 | if (!__test_and_set_bit(UIO_IRQ_DISABLED, &priv->flags)) |
96 | disable_irq_nosync(irq: dev_info->irq); |
97 | } |
98 | spin_unlock_irqrestore(lock: &priv->lock, flags); |
99 | |
100 | return 0; |
101 | } |
102 | |
103 | static void uio_pdrv_genirq_cleanup(void *data) |
104 | { |
105 | struct device *dev = data; |
106 | |
107 | pm_runtime_disable(dev); |
108 | } |
109 | |
110 | static int uio_pdrv_genirq_probe(struct platform_device *pdev) |
111 | { |
112 | struct uio_info *uioinfo = dev_get_platdata(dev: &pdev->dev); |
113 | struct device_node *node = pdev->dev.of_node; |
114 | struct uio_pdrv_genirq_platdata *priv; |
115 | struct uio_mem *uiomem; |
116 | int ret = -EINVAL; |
117 | int i; |
118 | |
119 | if (node) { |
120 | const char *name; |
121 | |
122 | /* alloc uioinfo for one device */ |
123 | uioinfo = devm_kzalloc(dev: &pdev->dev, size: sizeof(*uioinfo), |
124 | GFP_KERNEL); |
125 | if (!uioinfo) { |
126 | dev_err(&pdev->dev, "unable to kmalloc\n" ); |
127 | return -ENOMEM; |
128 | } |
129 | |
130 | if (!of_property_read_string(np: node, propname: "linux,uio-name" , out_string: &name)) |
131 | uioinfo->name = devm_kstrdup(dev: &pdev->dev, s: name, GFP_KERNEL); |
132 | else |
133 | uioinfo->name = devm_kasprintf(dev: &pdev->dev, GFP_KERNEL, |
134 | fmt: "%pOFn" , node); |
135 | |
136 | uioinfo->version = "devicetree" ; |
137 | /* Multiple IRQs are not supported */ |
138 | } |
139 | |
140 | if (!uioinfo || !uioinfo->name || !uioinfo->version) { |
141 | dev_err(&pdev->dev, "missing platform_data\n" ); |
142 | return ret; |
143 | } |
144 | |
145 | if (uioinfo->handler || uioinfo->irqcontrol || |
146 | uioinfo->irq_flags & IRQF_SHARED) { |
147 | dev_err(&pdev->dev, "interrupt configuration error\n" ); |
148 | return ret; |
149 | } |
150 | |
151 | priv = devm_kzalloc(dev: &pdev->dev, size: sizeof(*priv), GFP_KERNEL); |
152 | if (!priv) { |
153 | dev_err(&pdev->dev, "unable to kmalloc\n" ); |
154 | return -ENOMEM; |
155 | } |
156 | |
157 | priv->uioinfo = uioinfo; |
158 | spin_lock_init(&priv->lock); |
159 | priv->flags = 0; /* interrupt is enabled to begin with */ |
160 | priv->pdev = pdev; |
161 | |
162 | if (!uioinfo->irq) { |
163 | ret = platform_get_irq_optional(pdev, 0); |
164 | uioinfo->irq = ret; |
165 | if (ret == -ENXIO) |
166 | uioinfo->irq = UIO_IRQ_NONE; |
167 | else if (ret == -EPROBE_DEFER) |
168 | return ret; |
169 | else if (ret < 0) { |
170 | dev_err(&pdev->dev, "failed to get IRQ\n" ); |
171 | return ret; |
172 | } |
173 | } |
174 | |
175 | if (uioinfo->irq) { |
176 | struct irq_data *irq_data = irq_get_irq_data(irq: uioinfo->irq); |
177 | |
178 | /* |
179 | * If a level interrupt, dont do lazy disable. Otherwise the |
180 | * irq will fire again since clearing of the actual cause, on |
181 | * device level, is done in userspace |
182 | * irqd_is_level_type() isn't used since isn't valid until |
183 | * irq is configured. |
184 | */ |
185 | if (irq_data && |
186 | irqd_get_trigger_type(d: irq_data) & IRQ_TYPE_LEVEL_MASK) { |
187 | dev_dbg(&pdev->dev, "disable lazy unmask\n" ); |
188 | irq_set_status_flags(irq: uioinfo->irq, set: IRQ_DISABLE_UNLAZY); |
189 | } |
190 | } |
191 | |
192 | uiomem = &uioinfo->mem[0]; |
193 | |
194 | for (i = 0; i < pdev->num_resources; ++i) { |
195 | struct resource *r = &pdev->resource[i]; |
196 | |
197 | if (r->flags != IORESOURCE_MEM) |
198 | continue; |
199 | |
200 | if (uiomem >= &uioinfo->mem[MAX_UIO_MAPS]) { |
201 | dev_warn(&pdev->dev, "device has more than " |
202 | __stringify(MAX_UIO_MAPS) |
203 | " I/O memory resources.\n" ); |
204 | break; |
205 | } |
206 | |
207 | uiomem->memtype = UIO_MEM_PHYS; |
208 | uiomem->addr = r->start & PAGE_MASK; |
209 | uiomem->offs = r->start & ~PAGE_MASK; |
210 | uiomem->size = (uiomem->offs + resource_size(res: r) |
211 | + PAGE_SIZE - 1) & PAGE_MASK; |
212 | uiomem->name = r->name; |
213 | ++uiomem; |
214 | } |
215 | |
216 | while (uiomem < &uioinfo->mem[MAX_UIO_MAPS]) { |
217 | uiomem->size = 0; |
218 | ++uiomem; |
219 | } |
220 | |
221 | /* This driver requires no hardware specific kernel code to handle |
222 | * interrupts. Instead, the interrupt handler simply disables the |
223 | * interrupt in the interrupt controller. User space is responsible |
224 | * for performing hardware specific acknowledge and re-enabling of |
225 | * the interrupt in the interrupt controller. |
226 | * |
227 | * Interrupt sharing is not supported. |
228 | */ |
229 | |
230 | uioinfo->handler = uio_pdrv_genirq_handler; |
231 | uioinfo->irqcontrol = uio_pdrv_genirq_irqcontrol; |
232 | uioinfo->open = uio_pdrv_genirq_open; |
233 | uioinfo->release = uio_pdrv_genirq_release; |
234 | uioinfo->priv = priv; |
235 | |
236 | /* Enable Runtime PM for this device: |
237 | * The device starts in suspended state to allow the hardware to be |
238 | * turned off by default. The Runtime PM bus code should power on the |
239 | * hardware and enable clocks at open(). |
240 | */ |
241 | pm_runtime_enable(dev: &pdev->dev); |
242 | |
243 | ret = devm_add_action_or_reset(&pdev->dev, uio_pdrv_genirq_cleanup, |
244 | &pdev->dev); |
245 | if (ret) |
246 | return ret; |
247 | |
248 | ret = devm_uio_register_device(&pdev->dev, priv->uioinfo); |
249 | if (ret) |
250 | dev_err(&pdev->dev, "unable to register uio device\n" ); |
251 | |
252 | return ret; |
253 | } |
254 | |
255 | static int uio_pdrv_genirq_runtime_nop(struct device *dev) |
256 | { |
257 | /* Runtime PM callback shared between ->runtime_suspend() |
258 | * and ->runtime_resume(). Simply returns success. |
259 | * |
260 | * In this driver pm_runtime_get_sync() and pm_runtime_put_sync() |
261 | * are used at open() and release() time. This allows the |
262 | * Runtime PM code to turn off power to the device while the |
263 | * device is unused, ie before open() and after release(). |
264 | * |
265 | * This Runtime PM callback does not need to save or restore |
266 | * any registers since user space is responsbile for hardware |
267 | * register reinitialization after open(). |
268 | */ |
269 | return 0; |
270 | } |
271 | |
272 | static const struct dev_pm_ops uio_pdrv_genirq_dev_pm_ops = { |
273 | .runtime_suspend = uio_pdrv_genirq_runtime_nop, |
274 | .runtime_resume = uio_pdrv_genirq_runtime_nop, |
275 | }; |
276 | |
277 | #ifdef CONFIG_OF |
278 | static struct of_device_id uio_of_genirq_match[] = { |
279 | { /* This is filled with module_parm */ }, |
280 | { /* Sentinel */ }, |
281 | }; |
282 | MODULE_DEVICE_TABLE(of, uio_of_genirq_match); |
283 | module_param_string(of_id, uio_of_genirq_match[0].compatible, 128, 0); |
284 | MODULE_PARM_DESC(of_id, "Openfirmware id of the device to be handled by uio" ); |
285 | #endif |
286 | |
287 | static struct platform_driver uio_pdrv_genirq = { |
288 | .probe = uio_pdrv_genirq_probe, |
289 | .driver = { |
290 | .name = DRIVER_NAME, |
291 | .pm = &uio_pdrv_genirq_dev_pm_ops, |
292 | .of_match_table = of_match_ptr(uio_of_genirq_match), |
293 | }, |
294 | }; |
295 | |
296 | module_platform_driver(uio_pdrv_genirq); |
297 | |
298 | MODULE_AUTHOR("Magnus Damm" ); |
299 | MODULE_DESCRIPTION("Userspace I/O platform driver with generic IRQ handling" ); |
300 | MODULE_LICENSE("GPL v2" ); |
301 | MODULE_ALIAS("platform:" DRIVER_NAME); |
302 | |