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Linux/drivers/virtio/virtio_mmio.c

  1 /*
  2  * Virtio memory mapped device driver
  3  *
  4  * Copyright 2011-2014, ARM Ltd.
  5  *
  6  * This module allows virtio devices to be used over a virtual, memory mapped
  7  * platform device.
  8  *
  9  * The guest device(s) may be instantiated in one of three equivalent ways:
 10  *
 11  * 1. Static platform device in board's code, eg.:
 12  *
 13  *      static struct platform_device v2m_virtio_device = {
 14  *              .name = "virtio-mmio",
 15  *              .id = -1,
 16  *              .num_resources = 2,
 17  *              .resource = (struct resource []) {
 18  *                      {
 19  *                              .start = 0x1001e000,
 20  *                              .end = 0x1001e0ff,
 21  *                              .flags = IORESOURCE_MEM,
 22  *                      }, {
 23  *                              .start = 42 + 32,
 24  *                              .end = 42 + 32,
 25  *                              .flags = IORESOURCE_IRQ,
 26  *                      },
 27  *              }
 28  *      };
 29  *
 30  * 2. Device Tree node, eg.:
 31  *
 32  *              virtio_block@1e000 {
 33  *                      compatible = "virtio,mmio";
 34  *                      reg = <0x1e000 0x100>;
 35  *                      interrupts = <42>;
 36  *              }
 37  *
 38  * 3. Kernel module (or command line) parameter. Can be used more than once -
 39  *    one device will be created for each one. Syntax:
 40  *
 41  *              [virtio_mmio.]device=<size>@<baseaddr>:<irq>[:<id>]
 42  *    where:
 43  *              <size>     := size (can use standard suffixes like K, M or G)
 44  *              <baseaddr> := physical base address
 45  *              <irq>      := interrupt number (as passed to request_irq())
 46  *              <id>       := (optional) platform device id
 47  *    eg.:
 48  *              virtio_mmio.device=0x100@0x100b0000:48 \
 49  *                              virtio_mmio.device=1K@0x1001e000:74
 50  *
 51  *
 52  *
 53  * Based on Virtio PCI driver by Anthony Liguori, copyright IBM Corp. 2007
 54  *
 55  * This work is licensed under the terms of the GNU GPL, version 2 or later.
 56  * See the COPYING file in the top-level directory.
 57  */
 58 
 59 #define pr_fmt(fmt) "virtio-mmio: " fmt
 60 
 61 #include <linux/acpi.h>
 62 #include <linux/highmem.h>
 63 #include <linux/interrupt.h>
 64 #include <linux/io.h>
 65 #include <linux/list.h>
 66 #include <linux/module.h>
 67 #include <linux/platform_device.h>
 68 #include <linux/slab.h>
 69 #include <linux/spinlock.h>
 70 #include <linux/virtio.h>
 71 #include <linux/virtio_config.h>
 72 #include <linux/virtio_mmio.h>
 73 #include <linux/virtio_ring.h>
 74 
 75 
 76 
 77 /* The alignment to use between consumer and producer parts of vring.
 78  * Currently hardcoded to the page size. */
 79 #define VIRTIO_MMIO_VRING_ALIGN         PAGE_SIZE
 80 
 81 
 82 
 83 #define to_virtio_mmio_device(_plat_dev) \
 84         container_of(_plat_dev, struct virtio_mmio_device, vdev)
 85 
 86 struct virtio_mmio_device {
 87         struct virtio_device vdev;
 88         struct platform_device *pdev;
 89 
 90         void __iomem *base;
 91         unsigned long version;
 92 
 93         /* a list of queues so we can dispatch IRQs */
 94         spinlock_t lock;
 95         struct list_head virtqueues;
 96 };
 97 
 98 struct virtio_mmio_vq_info {
 99         /* the actual virtqueue */
100         struct virtqueue *vq;
101 
102         /* the list node for the virtqueues list */
103         struct list_head node;
104 };
105 
106 
107 
108 /* Configuration interface */
109 
110 static u64 vm_get_features(struct virtio_device *vdev)
111 {
112         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
113         u64 features;
114 
115         writel(1, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
116         features = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
117         features <<= 32;
118 
119         writel(0, vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES_SEL);
120         features |= readl(vm_dev->base + VIRTIO_MMIO_DEVICE_FEATURES);
121 
122         return features;
123 }
124 
125 static int vm_finalize_features(struct virtio_device *vdev)
126 {
127         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
128 
129         /* Give virtio_ring a chance to accept features. */
130         vring_transport_features(vdev);
131 
132         /* Make sure there is are no mixed devices */
133         if (vm_dev->version == 2 &&
134                         !__virtio_test_bit(vdev, VIRTIO_F_VERSION_1)) {
135                 dev_err(&vdev->dev, "New virtio-mmio devices (version 2) must provide VIRTIO_F_VERSION_1 feature!\n");
136                 return -EINVAL;
137         }
138 
139         writel(1, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
140         writel((u32)(vdev->features >> 32),
141                         vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
142 
143         writel(0, vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES_SEL);
144         writel((u32)vdev->features,
145                         vm_dev->base + VIRTIO_MMIO_DRIVER_FEATURES);
146 
147         return 0;
148 }
149 
150 static void vm_get(struct virtio_device *vdev, unsigned offset,
151                    void *buf, unsigned len)
152 {
153         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
154         void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;
155         u8 b;
156         __le16 w;
157         __le32 l;
158 
159         if (vm_dev->version == 1) {
160                 u8 *ptr = buf;
161                 int i;
162 
163                 for (i = 0; i < len; i++)
164                         ptr[i] = readb(base + offset + i);
165                 return;
166         }
167 
168         switch (len) {
169         case 1:
170                 b = readb(base + offset);
171                 memcpy(buf, &b, sizeof b);
172                 break;
173         case 2:
174                 w = cpu_to_le16(readw(base + offset));
175                 memcpy(buf, &w, sizeof w);
176                 break;
177         case 4:
178                 l = cpu_to_le32(readl(base + offset));
179                 memcpy(buf, &l, sizeof l);
180                 break;
181         case 8:
182                 l = cpu_to_le32(readl(base + offset));
183                 memcpy(buf, &l, sizeof l);
184                 l = cpu_to_le32(ioread32(base + offset + sizeof l));
185                 memcpy(buf + sizeof l, &l, sizeof l);
186                 break;
187         default:
188                 BUG();
189         }
190 }
191 
192 static void vm_set(struct virtio_device *vdev, unsigned offset,
193                    const void *buf, unsigned len)
194 {
195         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
196         void __iomem *base = vm_dev->base + VIRTIO_MMIO_CONFIG;
197         u8 b;
198         __le16 w;
199         __le32 l;
200 
201         if (vm_dev->version == 1) {
202                 const u8 *ptr = buf;
203                 int i;
204 
205                 for (i = 0; i < len; i++)
206                         writeb(ptr[i], base + offset + i);
207 
208                 return;
209         }
210 
211         switch (len) {
212         case 1:
213                 memcpy(&b, buf, sizeof b);
214                 writeb(b, base + offset);
215                 break;
216         case 2:
217                 memcpy(&w, buf, sizeof w);
218                 writew(le16_to_cpu(w), base + offset);
219                 break;
220         case 4:
221                 memcpy(&l, buf, sizeof l);
222                 writel(le32_to_cpu(l), base + offset);
223                 break;
224         case 8:
225                 memcpy(&l, buf, sizeof l);
226                 writel(le32_to_cpu(l), base + offset);
227                 memcpy(&l, buf + sizeof l, sizeof l);
228                 writel(le32_to_cpu(l), base + offset + sizeof l);
229                 break;
230         default:
231                 BUG();
232         }
233 }
234 
235 static u32 vm_generation(struct virtio_device *vdev)
236 {
237         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
238 
239         if (vm_dev->version == 1)
240                 return 0;
241         else
242                 return readl(vm_dev->base + VIRTIO_MMIO_CONFIG_GENERATION);
243 }
244 
245 static u8 vm_get_status(struct virtio_device *vdev)
246 {
247         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
248 
249         return readl(vm_dev->base + VIRTIO_MMIO_STATUS) & 0xff;
250 }
251 
252 static void vm_set_status(struct virtio_device *vdev, u8 status)
253 {
254         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
255 
256         /* We should never be setting status to 0. */
257         BUG_ON(status == 0);
258 
259         writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
260 }
261 
262 static void vm_reset(struct virtio_device *vdev)
263 {
264         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
265 
266         /* 0 status means a reset. */
267         writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
268 }
269 
270 
271 
272 /* Transport interface */
273 
274 /* the notify function used when creating a virt queue */
275 static bool vm_notify(struct virtqueue *vq)
276 {
277         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
278 
279         /* We write the queue's selector into the notification register to
280          * signal the other end */
281         writel(vq->index, vm_dev->base + VIRTIO_MMIO_QUEUE_NOTIFY);
282         return true;
283 }
284 
285 /* Notify all virtqueues on an interrupt. */
286 static irqreturn_t vm_interrupt(int irq, void *opaque)
287 {
288         struct virtio_mmio_device *vm_dev = opaque;
289         struct virtio_mmio_vq_info *info;
290         unsigned long status;
291         unsigned long flags;
292         irqreturn_t ret = IRQ_NONE;
293 
294         /* Read and acknowledge interrupts */
295         status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
296         writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
297 
298         if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)) {
299                 virtio_config_changed(&vm_dev->vdev);
300                 ret = IRQ_HANDLED;
301         }
302 
303         if (likely(status & VIRTIO_MMIO_INT_VRING)) {
304                 spin_lock_irqsave(&vm_dev->lock, flags);
305                 list_for_each_entry(info, &vm_dev->virtqueues, node)
306                         ret |= vring_interrupt(irq, info->vq);
307                 spin_unlock_irqrestore(&vm_dev->lock, flags);
308         }
309 
310         return ret;
311 }
312 
313 
314 
315 static void vm_del_vq(struct virtqueue *vq)
316 {
317         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vq->vdev);
318         struct virtio_mmio_vq_info *info = vq->priv;
319         unsigned long flags;
320         unsigned int index = vq->index;
321 
322         spin_lock_irqsave(&vm_dev->lock, flags);
323         list_del(&info->node);
324         spin_unlock_irqrestore(&vm_dev->lock, flags);
325 
326         /* Select and deactivate the queue */
327         writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
328         if (vm_dev->version == 1) {
329                 writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
330         } else {
331                 writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
332                 WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
333         }
334 
335         vring_del_virtqueue(vq);
336 
337         kfree(info);
338 }
339 
340 static void vm_del_vqs(struct virtio_device *vdev)
341 {
342         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
343         struct virtqueue *vq, *n;
344 
345         list_for_each_entry_safe(vq, n, &vdev->vqs, list)
346                 vm_del_vq(vq);
347 
348         free_irq(platform_get_irq(vm_dev->pdev, 0), vm_dev);
349 }
350 
351 static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
352                                   void (*callback)(struct virtqueue *vq),
353                                   const char *name)
354 {
355         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
356         struct virtio_mmio_vq_info *info;
357         struct virtqueue *vq;
358         unsigned long flags;
359         unsigned int num;
360         int err;
361 
362         if (!name)
363                 return NULL;
364 
365         /* Select the queue we're interested in */
366         writel(index, vm_dev->base + VIRTIO_MMIO_QUEUE_SEL);
367 
368         /* Queue shouldn't already be set up. */
369         if (readl(vm_dev->base + (vm_dev->version == 1 ?
370                         VIRTIO_MMIO_QUEUE_PFN : VIRTIO_MMIO_QUEUE_READY))) {
371                 err = -ENOENT;
372                 goto error_available;
373         }
374 
375         /* Allocate and fill out our active queue description */
376         info = kmalloc(sizeof(*info), GFP_KERNEL);
377         if (!info) {
378                 err = -ENOMEM;
379                 goto error_kmalloc;
380         }
381 
382         num = readl(vm_dev->base + VIRTIO_MMIO_QUEUE_NUM_MAX);
383         if (num == 0) {
384                 err = -ENOENT;
385                 goto error_new_virtqueue;
386         }
387 
388         /* Create the vring */
389         vq = vring_create_virtqueue(index, num, VIRTIO_MMIO_VRING_ALIGN, vdev,
390                                  true, true, vm_notify, callback, name);
391         if (!vq) {
392                 err = -ENOMEM;
393                 goto error_new_virtqueue;
394         }
395 
396         /* Activate the queue */
397         writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
398         if (vm_dev->version == 1) {
399                 writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
400                 writel(virtqueue_get_desc_addr(vq) >> PAGE_SHIFT,
401                                 vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
402         } else {
403                 u64 addr;
404 
405                 addr = virtqueue_get_desc_addr(vq);
406                 writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_LOW);
407                 writel((u32)(addr >> 32),
408                                 vm_dev->base + VIRTIO_MMIO_QUEUE_DESC_HIGH);
409 
410                 addr = virtqueue_get_avail_addr(vq);
411                 writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_LOW);
412                 writel((u32)(addr >> 32),
413                                 vm_dev->base + VIRTIO_MMIO_QUEUE_AVAIL_HIGH);
414 
415                 addr = virtqueue_get_used_addr(vq);
416                 writel((u32)addr, vm_dev->base + VIRTIO_MMIO_QUEUE_USED_LOW);
417                 writel((u32)(addr >> 32),
418                                 vm_dev->base + VIRTIO_MMIO_QUEUE_USED_HIGH);
419 
420                 writel(1, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
421         }
422 
423         vq->priv = info;
424         info->vq = vq;
425 
426         spin_lock_irqsave(&vm_dev->lock, flags);
427         list_add(&info->node, &vm_dev->virtqueues);
428         spin_unlock_irqrestore(&vm_dev->lock, flags);
429 
430         return vq;
431 
432 error_new_virtqueue:
433         if (vm_dev->version == 1) {
434                 writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
435         } else {
436                 writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_READY);
437                 WARN_ON(readl(vm_dev->base + VIRTIO_MMIO_QUEUE_READY));
438         }
439         kfree(info);
440 error_kmalloc:
441 error_available:
442         return ERR_PTR(err);
443 }
444 
445 static int vm_find_vqs(struct virtio_device *vdev, unsigned nvqs,
446                        struct virtqueue *vqs[],
447                        vq_callback_t *callbacks[],
448                        const char * const names[])
449 {
450         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
451         unsigned int irq = platform_get_irq(vm_dev->pdev, 0);
452         int i, err;
453 
454         err = request_irq(irq, vm_interrupt, IRQF_SHARED,
455                         dev_name(&vdev->dev), vm_dev);
456         if (err)
457                 return err;
458 
459         for (i = 0; i < nvqs; ++i) {
460                 vqs[i] = vm_setup_vq(vdev, i, callbacks[i], names[i]);
461                 if (IS_ERR(vqs[i])) {
462                         vm_del_vqs(vdev);
463                         return PTR_ERR(vqs[i]);
464                 }
465         }
466 
467         return 0;
468 }
469 
470 static const char *vm_bus_name(struct virtio_device *vdev)
471 {
472         struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
473 
474         return vm_dev->pdev->name;
475 }
476 
477 static const struct virtio_config_ops virtio_mmio_config_ops = {
478         .get            = vm_get,
479         .set            = vm_set,
480         .generation     = vm_generation,
481         .get_status     = vm_get_status,
482         .set_status     = vm_set_status,
483         .reset          = vm_reset,
484         .find_vqs       = vm_find_vqs,
485         .del_vqs        = vm_del_vqs,
486         .get_features   = vm_get_features,
487         .finalize_features = vm_finalize_features,
488         .bus_name       = vm_bus_name,
489 };
490 
491 
492 
493 /* Platform device */
494 
495 static int virtio_mmio_probe(struct platform_device *pdev)
496 {
497         struct virtio_mmio_device *vm_dev;
498         struct resource *mem;
499         unsigned long magic;
500 
501         mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
502         if (!mem)
503                 return -EINVAL;
504 
505         if (!devm_request_mem_region(&pdev->dev, mem->start,
506                         resource_size(mem), pdev->name))
507                 return -EBUSY;
508 
509         vm_dev = devm_kzalloc(&pdev->dev, sizeof(*vm_dev), GFP_KERNEL);
510         if (!vm_dev)
511                 return  -ENOMEM;
512 
513         vm_dev->vdev.dev.parent = &pdev->dev;
514         vm_dev->vdev.config = &virtio_mmio_config_ops;
515         vm_dev->pdev = pdev;
516         INIT_LIST_HEAD(&vm_dev->virtqueues);
517         spin_lock_init(&vm_dev->lock);
518 
519         vm_dev->base = devm_ioremap(&pdev->dev, mem->start, resource_size(mem));
520         if (vm_dev->base == NULL)
521                 return -EFAULT;
522 
523         /* Check magic value */
524         magic = readl(vm_dev->base + VIRTIO_MMIO_MAGIC_VALUE);
525         if (magic != ('v' | 'i' << 8 | 'r' << 16 | 't' << 24)) {
526                 dev_warn(&pdev->dev, "Wrong magic value 0x%08lx!\n", magic);
527                 return -ENODEV;
528         }
529 
530         /* Check device version */
531         vm_dev->version = readl(vm_dev->base + VIRTIO_MMIO_VERSION);
532         if (vm_dev->version < 1 || vm_dev->version > 2) {
533                 dev_err(&pdev->dev, "Version %ld not supported!\n",
534                                 vm_dev->version);
535                 return -ENXIO;
536         }
537 
538         vm_dev->vdev.id.device = readl(vm_dev->base + VIRTIO_MMIO_DEVICE_ID);
539         if (vm_dev->vdev.id.device == 0) {
540                 /*
541                  * virtio-mmio device with an ID 0 is a (dummy) placeholder
542                  * with no function. End probing now with no error reported.
543                  */
544                 return -ENODEV;
545         }
546         vm_dev->vdev.id.vendor = readl(vm_dev->base + VIRTIO_MMIO_VENDOR_ID);
547 
548         if (vm_dev->version == 1)
549                 writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_GUEST_PAGE_SIZE);
550 
551         platform_set_drvdata(pdev, vm_dev);
552 
553         return register_virtio_device(&vm_dev->vdev);
554 }
555 
556 static int virtio_mmio_remove(struct platform_device *pdev)
557 {
558         struct virtio_mmio_device *vm_dev = platform_get_drvdata(pdev);
559 
560         unregister_virtio_device(&vm_dev->vdev);
561 
562         return 0;
563 }
564 
565 
566 
567 /* Devices list parameter */
568 
569 #if defined(CONFIG_VIRTIO_MMIO_CMDLINE_DEVICES)
570 
571 static struct device vm_cmdline_parent = {
572         .init_name = "virtio-mmio-cmdline",
573 };
574 
575 static int vm_cmdline_parent_registered;
576 static int vm_cmdline_id;
577 
578 static int vm_cmdline_set(const char *device,
579                 const struct kernel_param *kp)
580 {
581         int err;
582         struct resource resources[2] = {};
583         char *str;
584         long long int base, size;
585         unsigned int irq;
586         int processed, consumed = 0;
587         struct platform_device *pdev;
588 
589         /* Consume "size" part of the command line parameter */
590         size = memparse(device, &str);
591 
592         /* Get "@<base>:<irq>[:<id>]" chunks */
593         processed = sscanf(str, "@%lli:%u%n:%d%n",
594                         &base, &irq, &consumed,
595                         &vm_cmdline_id, &consumed);
596 
597         /*
598          * sscanf() must processes at least 2 chunks; also there
599          * must be no extra characters after the last chunk, so
600          * str[consumed] must be '\0'
601          */
602         if (processed < 2 || str[consumed])
603                 return -EINVAL;
604 
605         resources[0].flags = IORESOURCE_MEM;
606         resources[0].start = base;
607         resources[0].end = base + size - 1;
608 
609         resources[1].flags = IORESOURCE_IRQ;
610         resources[1].start = resources[1].end = irq;
611 
612         if (!vm_cmdline_parent_registered) {
613                 err = device_register(&vm_cmdline_parent);
614                 if (err) {
615                         pr_err("Failed to register parent device!\n");
616                         return err;
617                 }
618                 vm_cmdline_parent_registered = 1;
619         }
620 
621         pr_info("Registering device virtio-mmio.%d at 0x%llx-0x%llx, IRQ %d.\n",
622                        vm_cmdline_id,
623                        (unsigned long long)resources[0].start,
624                        (unsigned long long)resources[0].end,
625                        (int)resources[1].start);
626 
627         pdev = platform_device_register_resndata(&vm_cmdline_parent,
628                         "virtio-mmio", vm_cmdline_id++,
629                         resources, ARRAY_SIZE(resources), NULL, 0);
630         if (IS_ERR(pdev))
631                 return PTR_ERR(pdev);
632 
633         return 0;
634 }
635 
636 static int vm_cmdline_get_device(struct device *dev, void *data)
637 {
638         char *buffer = data;
639         unsigned int len = strlen(buffer);
640         struct platform_device *pdev = to_platform_device(dev);
641 
642         snprintf(buffer + len, PAGE_SIZE - len, "0x%llx@0x%llx:%llu:%d\n",
643                         pdev->resource[0].end - pdev->resource[0].start + 1ULL,
644                         (unsigned long long)pdev->resource[0].start,
645                         (unsigned long long)pdev->resource[1].start,
646                         pdev->id);
647         return 0;
648 }
649 
650 static int vm_cmdline_get(char *buffer, const struct kernel_param *kp)
651 {
652         buffer[0] = '\0';
653         device_for_each_child(&vm_cmdline_parent, buffer,
654                         vm_cmdline_get_device);
655         return strlen(buffer) + 1;
656 }
657 
658 static const struct kernel_param_ops vm_cmdline_param_ops = {
659         .set = vm_cmdline_set,
660         .get = vm_cmdline_get,
661 };
662 
663 device_param_cb(device, &vm_cmdline_param_ops, NULL, S_IRUSR);
664 
665 static int vm_unregister_cmdline_device(struct device *dev,
666                 void *data)
667 {
668         platform_device_unregister(to_platform_device(dev));
669 
670         return 0;
671 }
672 
673 static void vm_unregister_cmdline_devices(void)
674 {
675         if (vm_cmdline_parent_registered) {
676                 device_for_each_child(&vm_cmdline_parent, NULL,
677                                 vm_unregister_cmdline_device);
678                 device_unregister(&vm_cmdline_parent);
679                 vm_cmdline_parent_registered = 0;
680         }
681 }
682 
683 #else
684 
685 static void vm_unregister_cmdline_devices(void)
686 {
687 }
688 
689 #endif
690 
691 /* Platform driver */
692 
693 static struct of_device_id virtio_mmio_match[] = {
694         { .compatible = "virtio,mmio", },
695         {},
696 };
697 MODULE_DEVICE_TABLE(of, virtio_mmio_match);
698 
699 #ifdef CONFIG_ACPI
700 static const struct acpi_device_id virtio_mmio_acpi_match[] = {
701         { "LNRO0005", },
702         { }
703 };
704 MODULE_DEVICE_TABLE(acpi, virtio_mmio_acpi_match);
705 #endif
706 
707 static struct platform_driver virtio_mmio_driver = {
708         .probe          = virtio_mmio_probe,
709         .remove         = virtio_mmio_remove,
710         .driver         = {
711                 .name   = "virtio-mmio",
712                 .of_match_table = virtio_mmio_match,
713                 .acpi_match_table = ACPI_PTR(virtio_mmio_acpi_match),
714         },
715 };
716 
717 static int __init virtio_mmio_init(void)
718 {
719         return platform_driver_register(&virtio_mmio_driver);
720 }
721 
722 static void __exit virtio_mmio_exit(void)
723 {
724         platform_driver_unregister(&virtio_mmio_driver);
725         vm_unregister_cmdline_devices();
726 }
727 
728 module_init(virtio_mmio_init);
729 module_exit(virtio_mmio_exit);
730 
731 MODULE_AUTHOR("Pawel Moll <pawel.moll@arm.com>");
732 MODULE_DESCRIPTION("Platform bus driver for memory mapped virtio devices");
733 MODULE_LICENSE("GPL");
734 

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