1 // SPDX-License-Identifier: GPL-2.0+
3 * GPIO driver for virtio-based virtual GPIO controllers
5 * Copyright (C) 2021 metux IT consult
6 * Enrico Weigelt, metux IT consult <info@metux.net>
8 * Copyright (C) 2021 Linaro.
9 * Viresh Kumar <viresh.kumar@linaro.org>
12 #include <linux/completion.h>
13 #include <linux/err.h>
14 #include <linux/gpio/driver.h>
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/mutex.h>
19 #include <linux/spinlock.h>
20 #include <linux/virtio_config.h>
21 #include <uapi/linux/virtio_gpio.h>
22 #include <uapi/linux/virtio_ids.h>
24 struct virtio_gpio_line {
25 struct mutex lock; /* Protects line operation */
26 struct completion completion;
27 struct virtio_gpio_request req ____cacheline_aligned;
28 struct virtio_gpio_response res ____cacheline_aligned;
32 struct vgpio_irq_line {
40 struct virtio_gpio_irq_request ireq ____cacheline_aligned;
41 struct virtio_gpio_irq_response ires ____cacheline_aligned;
45 struct virtio_device *vdev;
46 struct mutex lock; /* Protects virtqueue operation */
48 struct virtio_gpio_line *lines;
49 struct virtqueue *request_vq;
52 struct virtqueue *event_vq;
53 struct mutex irq_lock; /* Protects irq operation */
54 raw_spinlock_t eventq_lock; /* Protects queuing of the buffer */
55 struct vgpio_irq_line *irq_lines;
58 static int _virtio_gpio_req(struct virtio_gpio *vgpio, u16 type, u16 gpio,
59 u8 txvalue, u8 *rxvalue, void *response, u32 rxlen)
61 struct virtio_gpio_line *line = &vgpio->lines[gpio];
62 struct virtio_gpio_request *req = &line->req;
63 struct virtio_gpio_response *res = response;
64 struct scatterlist *sgs[2], req_sg, res_sg;
65 struct device *dev = &vgpio->vdev->dev;
69 * Prevent concurrent requests for the same line since we have
70 * pre-allocated request/response buffers for each GPIO line. Moreover
71 * Linux always accesses a GPIO line sequentially, so this locking shall
72 * always go through without any delays.
74 mutex_lock(&line->lock);
76 req->type = cpu_to_le16(type);
77 req->gpio = cpu_to_le16(gpio);
78 req->value = cpu_to_le32(txvalue);
80 sg_init_one(&req_sg, req, sizeof(*req));
81 sg_init_one(&res_sg, res, rxlen);
86 reinit_completion(&line->completion);
89 * Virtqueue callers need to ensure they don't call its APIs with other
90 * virtqueue operations at the same time.
92 mutex_lock(&vgpio->lock);
93 ret = virtqueue_add_sgs(vgpio->request_vq, sgs, 1, 1, line, GFP_KERNEL);
95 dev_err(dev, "failed to add request to vq\n");
96 mutex_unlock(&vgpio->lock);
100 virtqueue_kick(vgpio->request_vq);
101 mutex_unlock(&vgpio->lock);
103 if (!wait_for_completion_timeout(&line->completion, HZ)) {
104 dev_err(dev, "GPIO operation timed out\n");
109 if (unlikely(res->status != VIRTIO_GPIO_STATUS_OK)) {
110 dev_err(dev, "GPIO request failed: %d\n", gpio);
115 if (unlikely(line->rxlen != rxlen)) {
116 dev_err(dev, "GPIO operation returned incorrect len (%u : %u)\n",
123 *rxvalue = res->value;
126 mutex_unlock(&line->lock);
130 static int virtio_gpio_req(struct virtio_gpio *vgpio, u16 type, u16 gpio,
131 u8 txvalue, u8 *rxvalue)
133 struct virtio_gpio_line *line = &vgpio->lines[gpio];
134 struct virtio_gpio_response *res = &line->res;
136 return _virtio_gpio_req(vgpio, type, gpio, txvalue, rxvalue, res,
140 static void virtio_gpio_free(struct gpio_chip *gc, unsigned int gpio)
142 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
144 virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
145 VIRTIO_GPIO_DIRECTION_NONE, NULL);
148 static int virtio_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio)
150 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
154 ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_DIRECTION, gpio, 0,
160 case VIRTIO_GPIO_DIRECTION_IN:
161 return GPIO_LINE_DIRECTION_IN;
162 case VIRTIO_GPIO_DIRECTION_OUT:
163 return GPIO_LINE_DIRECTION_OUT;
169 static int virtio_gpio_direction_input(struct gpio_chip *gc, unsigned int gpio)
171 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
173 return virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
174 VIRTIO_GPIO_DIRECTION_IN, NULL);
177 static int virtio_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio,
180 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
183 ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_VALUE, gpio, value, NULL);
187 return virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
188 VIRTIO_GPIO_DIRECTION_OUT, NULL);
191 static int virtio_gpio_get(struct gpio_chip *gc, unsigned int gpio)
193 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
197 ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_VALUE, gpio, 0, &value);
198 return ret ? ret : value;
201 static void virtio_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
203 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
205 virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_VALUE, gpio, value, NULL);
208 /* Interrupt handling */
209 static void virtio_gpio_irq_prepare(struct virtio_gpio *vgpio, u16 gpio)
211 struct vgpio_irq_line *irq_line = &vgpio->irq_lines[gpio];
212 struct virtio_gpio_irq_request *ireq = &irq_line->ireq;
213 struct virtio_gpio_irq_response *ires = &irq_line->ires;
214 struct scatterlist *sgs[2], req_sg, res_sg;
217 if (WARN_ON(irq_line->queued || irq_line->masked || irq_line->disabled))
220 ireq->gpio = cpu_to_le16(gpio);
221 sg_init_one(&req_sg, ireq, sizeof(*ireq));
222 sg_init_one(&res_sg, ires, sizeof(*ires));
226 ret = virtqueue_add_sgs(vgpio->event_vq, sgs, 1, 1, irq_line, GFP_ATOMIC);
228 dev_err(&vgpio->vdev->dev, "failed to add request to eventq\n");
232 irq_line->queued = true;
233 virtqueue_kick(vgpio->event_vq);
236 static void virtio_gpio_irq_enable(struct irq_data *d)
238 struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
239 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
240 struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
242 raw_spin_lock(&vgpio->eventq_lock);
243 irq_line->disabled = false;
244 irq_line->masked = false;
245 irq_line->queue_pending = true;
246 raw_spin_unlock(&vgpio->eventq_lock);
248 irq_line->update_pending = true;
251 static void virtio_gpio_irq_disable(struct irq_data *d)
253 struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
254 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
255 struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
257 raw_spin_lock(&vgpio->eventq_lock);
258 irq_line->disabled = true;
259 irq_line->masked = true;
260 irq_line->queue_pending = false;
261 raw_spin_unlock(&vgpio->eventq_lock);
263 irq_line->update_pending = true;
266 static void virtio_gpio_irq_mask(struct irq_data *d)
268 struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
269 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
270 struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
272 raw_spin_lock(&vgpio->eventq_lock);
273 irq_line->masked = true;
274 raw_spin_unlock(&vgpio->eventq_lock);
277 static void virtio_gpio_irq_unmask(struct irq_data *d)
279 struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
280 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
281 struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
283 raw_spin_lock(&vgpio->eventq_lock);
284 irq_line->masked = false;
286 /* Queue the buffer unconditionally on unmask */
287 virtio_gpio_irq_prepare(vgpio, d->hwirq);
288 raw_spin_unlock(&vgpio->eventq_lock);
291 static int virtio_gpio_irq_set_type(struct irq_data *d, unsigned int type)
293 struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
294 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
295 struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
298 case IRQ_TYPE_EDGE_RISING:
299 type = VIRTIO_GPIO_IRQ_TYPE_EDGE_RISING;
301 case IRQ_TYPE_EDGE_FALLING:
302 type = VIRTIO_GPIO_IRQ_TYPE_EDGE_FALLING;
304 case IRQ_TYPE_EDGE_BOTH:
305 type = VIRTIO_GPIO_IRQ_TYPE_EDGE_BOTH;
307 case IRQ_TYPE_LEVEL_LOW:
308 type = VIRTIO_GPIO_IRQ_TYPE_LEVEL_LOW;
310 case IRQ_TYPE_LEVEL_HIGH:
311 type = VIRTIO_GPIO_IRQ_TYPE_LEVEL_HIGH;
314 dev_err(&vgpio->vdev->dev, "unsupported irq type: %u\n", type);
318 irq_line->type = type;
319 irq_line->update_pending = true;
324 static void virtio_gpio_irq_bus_lock(struct irq_data *d)
326 struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
327 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
329 mutex_lock(&vgpio->irq_lock);
332 static void virtio_gpio_irq_bus_sync_unlock(struct irq_data *d)
334 struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
335 struct virtio_gpio *vgpio = gpiochip_get_data(gc);
336 struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
337 u8 type = irq_line->disabled ? VIRTIO_GPIO_IRQ_TYPE_NONE : irq_line->type;
340 if (irq_line->update_pending) {
341 irq_line->update_pending = false;
342 virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_IRQ_TYPE, d->hwirq, type,
345 /* Queue the buffer only after interrupt is enabled */
346 raw_spin_lock_irqsave(&vgpio->eventq_lock, flags);
347 if (irq_line->queue_pending) {
348 irq_line->queue_pending = false;
349 virtio_gpio_irq_prepare(vgpio, d->hwirq);
351 raw_spin_unlock_irqrestore(&vgpio->eventq_lock, flags);
354 mutex_unlock(&vgpio->irq_lock);
357 static struct irq_chip vgpio_irq_chip = {
358 .name = "virtio-gpio",
359 .irq_enable = virtio_gpio_irq_enable,
360 .irq_disable = virtio_gpio_irq_disable,
361 .irq_mask = virtio_gpio_irq_mask,
362 .irq_unmask = virtio_gpio_irq_unmask,
363 .irq_set_type = virtio_gpio_irq_set_type,
365 /* These are required to implement irqchip for slow busses */
366 .irq_bus_lock = virtio_gpio_irq_bus_lock,
367 .irq_bus_sync_unlock = virtio_gpio_irq_bus_sync_unlock,
370 static bool ignore_irq(struct virtio_gpio *vgpio, int gpio,
371 struct vgpio_irq_line *irq_line)
375 raw_spin_lock(&vgpio->eventq_lock);
376 irq_line->queued = false;
378 /* Interrupt is disabled currently */
379 if (irq_line->masked || irq_line->disabled) {
385 * Buffer is returned as the interrupt was disabled earlier, but is
386 * enabled again now. Requeue the buffers.
388 if (irq_line->ires.status == VIRTIO_GPIO_IRQ_STATUS_INVALID) {
389 virtio_gpio_irq_prepare(vgpio, gpio);
394 if (WARN_ON(irq_line->ires.status != VIRTIO_GPIO_IRQ_STATUS_VALID))
398 raw_spin_unlock(&vgpio->eventq_lock);
403 static void virtio_gpio_event_vq(struct virtqueue *vq)
405 struct virtio_gpio *vgpio = vq->vdev->priv;
406 struct device *dev = &vgpio->vdev->dev;
407 struct vgpio_irq_line *irq_line;
412 irq_line = virtqueue_get_buf(vgpio->event_vq, &len);
416 if (len != sizeof(irq_line->ires)) {
417 dev_err(dev, "irq with incorrect length (%u : %u)\n",
418 len, (unsigned int)sizeof(irq_line->ires));
423 * Find GPIO line number from the offset of irq_line within the
424 * irq_lines block. We can also get GPIO number from
425 * irq-request, but better not to rely on a buffer returned by
428 gpio = irq_line - vgpio->irq_lines;
429 WARN_ON(gpio >= vgpio->gc.ngpio);
431 if (unlikely(ignore_irq(vgpio, gpio, irq_line)))
434 ret = generic_handle_domain_irq(vgpio->gc.irq.domain, gpio);
436 dev_err(dev, "failed to handle interrupt: %d\n", ret);
440 static void virtio_gpio_request_vq(struct virtqueue *vq)
442 struct virtio_gpio_line *line;
446 line = virtqueue_get_buf(vq, &len);
451 complete(&line->completion);
455 static void virtio_gpio_free_vqs(struct virtio_device *vdev)
457 vdev->config->reset(vdev);
458 vdev->config->del_vqs(vdev);
461 static int virtio_gpio_alloc_vqs(struct virtio_gpio *vgpio,
462 struct virtio_device *vdev)
464 const char * const names[] = { "requestq", "eventq" };
465 vq_callback_t *cbs[] = {
466 virtio_gpio_request_vq,
467 virtio_gpio_event_vq,
469 struct virtqueue *vqs[2] = { NULL, NULL };
472 ret = virtio_find_vqs(vdev, vgpio->irq_lines ? 2 : 1, vqs, cbs, names, NULL);
474 dev_err(&vdev->dev, "failed to find vqs: %d\n", ret);
479 dev_err(&vdev->dev, "failed to find requestq vq\n");
482 vgpio->request_vq = vqs[0];
484 if (vgpio->irq_lines && !vqs[1]) {
485 dev_err(&vdev->dev, "failed to find eventq vq\n");
488 vgpio->event_vq = vqs[1];
493 if (vqs[0] || vqs[1])
494 virtio_gpio_free_vqs(vdev);
499 static const char **virtio_gpio_get_names(struct virtio_gpio *vgpio,
500 u32 gpio_names_size, u16 ngpio)
502 struct virtio_gpio_response_get_names *res;
503 struct device *dev = &vgpio->vdev->dev;
504 u8 *gpio_names, *str;
508 if (!gpio_names_size)
511 len = sizeof(*res) + gpio_names_size;
512 res = devm_kzalloc(dev, len, GFP_KERNEL);
515 gpio_names = res->value;
517 ret = _virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_NAMES, 0, 0, NULL,
520 dev_err(dev, "Failed to get GPIO names: %d\n", ret);
524 names = devm_kcalloc(dev, ngpio, sizeof(*names), GFP_KERNEL);
528 /* NULL terminate the string instead of checking it */
529 gpio_names[gpio_names_size - 1] = '\0';
531 for (i = 0, str = gpio_names; i < ngpio; i++) {
533 str += strlen(str) + 1; /* zero-length strings are allowed */
535 if (str > gpio_names + gpio_names_size) {
536 dev_err(dev, "gpio_names block is too short (%d)\n", i);
544 static int virtio_gpio_probe(struct virtio_device *vdev)
546 struct virtio_gpio_config config;
547 struct device *dev = &vdev->dev;
548 struct virtio_gpio *vgpio;
553 vgpio = devm_kzalloc(dev, sizeof(*vgpio), GFP_KERNEL);
557 /* Read configuration */
558 virtio_cread_bytes(vdev, 0, &config, sizeof(config));
559 gpio_names_size = le32_to_cpu(config.gpio_names_size);
560 ngpio = le16_to_cpu(config.ngpio);
562 dev_err(dev, "Number of GPIOs can't be zero\n");
566 vgpio->lines = devm_kcalloc(dev, ngpio, sizeof(*vgpio->lines), GFP_KERNEL);
570 for (i = 0; i < ngpio; i++) {
571 mutex_init(&vgpio->lines[i].lock);
572 init_completion(&vgpio->lines[i].completion);
575 mutex_init(&vgpio->lock);
579 vgpio->gc.free = virtio_gpio_free;
580 vgpio->gc.get_direction = virtio_gpio_get_direction;
581 vgpio->gc.direction_input = virtio_gpio_direction_input;
582 vgpio->gc.direction_output = virtio_gpio_direction_output;
583 vgpio->gc.get = virtio_gpio_get;
584 vgpio->gc.set = virtio_gpio_set;
585 vgpio->gc.ngpio = ngpio;
586 vgpio->gc.base = -1; /* Allocate base dynamically */
587 vgpio->gc.label = dev_name(dev);
588 vgpio->gc.parent = dev;
589 vgpio->gc.owner = THIS_MODULE;
590 vgpio->gc.can_sleep = true;
592 /* Interrupt support */
593 if (virtio_has_feature(vdev, VIRTIO_GPIO_F_IRQ)) {
594 vgpio->irq_lines = devm_kcalloc(dev, ngpio, sizeof(*vgpio->irq_lines), GFP_KERNEL);
595 if (!vgpio->irq_lines)
598 /* The event comes from the outside so no parent handler */
599 vgpio->gc.irq.parent_handler = NULL;
600 vgpio->gc.irq.num_parents = 0;
601 vgpio->gc.irq.parents = NULL;
602 vgpio->gc.irq.default_type = IRQ_TYPE_NONE;
603 vgpio->gc.irq.handler = handle_level_irq;
604 vgpio->gc.irq.chip = &vgpio_irq_chip;
606 for (i = 0; i < ngpio; i++) {
607 vgpio->irq_lines[i].type = VIRTIO_GPIO_IRQ_TYPE_NONE;
608 vgpio->irq_lines[i].disabled = true;
609 vgpio->irq_lines[i].masked = true;
612 mutex_init(&vgpio->irq_lock);
613 raw_spin_lock_init(&vgpio->eventq_lock);
616 ret = virtio_gpio_alloc_vqs(vgpio, vdev);
620 /* Mark the device ready to perform operations from within probe() */
621 virtio_device_ready(vdev);
623 vgpio->gc.names = virtio_gpio_get_names(vgpio, gpio_names_size, ngpio);
625 ret = gpiochip_add_data(&vgpio->gc, vgpio);
627 virtio_gpio_free_vqs(vdev);
628 dev_err(dev, "Failed to add virtio-gpio controller\n");
634 static void virtio_gpio_remove(struct virtio_device *vdev)
636 struct virtio_gpio *vgpio = vdev->priv;
638 gpiochip_remove(&vgpio->gc);
639 virtio_gpio_free_vqs(vdev);
642 static const struct virtio_device_id id_table[] = {
643 { VIRTIO_ID_GPIO, VIRTIO_DEV_ANY_ID },
646 MODULE_DEVICE_TABLE(virtio, id_table);
648 static const unsigned int features[] = {
652 static struct virtio_driver virtio_gpio_driver = {
653 .feature_table = features,
654 .feature_table_size = ARRAY_SIZE(features),
655 .id_table = id_table,
656 .probe = virtio_gpio_probe,
657 .remove = virtio_gpio_remove,
659 .name = KBUILD_MODNAME,
660 .owner = THIS_MODULE,
663 module_virtio_driver(virtio_gpio_driver);
665 MODULE_AUTHOR("Enrico Weigelt, metux IT consult <info@metux.net>");
666 MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
667 MODULE_DESCRIPTION("VirtIO GPIO driver");
668 MODULE_LICENSE("GPL");