blob: fcc5e8c08973b3e797051b43b1af9bc36ef4d092 [file] [log] [blame] [edit]
// SPDX-License-Identifier: GPL-2.0+
/*
* GPIO driver for virtio-based virtual GPIO controllers
*
* Copyright (C) 2021 metux IT consult
* Enrico Weigelt, metux IT consult <info@metux.net>
*
* Copyright (C) 2021 Linaro.
* Viresh Kumar <viresh.kumar@linaro.org>
*/
#include <linux/completion.h>
#include <linux/err.h>
#include <linux/gpio/driver.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/virtio_config.h>
#include <uapi/linux/virtio_gpio.h>
#include <uapi/linux/virtio_ids.h>
struct virtio_gpio_line {
struct mutex lock; /* Protects line operation */
struct completion completion;
struct virtio_gpio_request req ____cacheline_aligned;
struct virtio_gpio_response res ____cacheline_aligned;
unsigned int rxlen;
};
struct vgpio_irq_line {
u8 type;
bool disabled;
bool masked;
bool queued;
bool update_pending;
bool queue_pending;
struct virtio_gpio_irq_request ireq ____cacheline_aligned;
struct virtio_gpio_irq_response ires ____cacheline_aligned;
};
struct virtio_gpio {
struct virtio_device *vdev;
struct mutex lock; /* Protects virtqueue operation */
struct gpio_chip gc;
struct virtio_gpio_line *lines;
struct virtqueue *request_vq;
/* irq support */
struct virtqueue *event_vq;
struct mutex irq_lock; /* Protects irq operation */
raw_spinlock_t eventq_lock; /* Protects queuing of the buffer */
struct vgpio_irq_line *irq_lines;
};
static int _virtio_gpio_req(struct virtio_gpio *vgpio, u16 type, u16 gpio,
u8 txvalue, u8 *rxvalue, void *response, u32 rxlen)
{
struct virtio_gpio_line *line = &vgpio->lines[gpio];
struct virtio_gpio_request *req = &line->req;
struct virtio_gpio_response *res = response;
struct scatterlist *sgs[2], req_sg, res_sg;
struct device *dev = &vgpio->vdev->dev;
int ret;
/*
* Prevent concurrent requests for the same line since we have
* pre-allocated request/response buffers for each GPIO line. Moreover
* Linux always accesses a GPIO line sequentially, so this locking shall
* always go through without any delays.
*/
mutex_lock(&line->lock);
req->type = cpu_to_le16(type);
req->gpio = cpu_to_le16(gpio);
req->value = cpu_to_le32(txvalue);
sg_init_one(&req_sg, req, sizeof(*req));
sg_init_one(&res_sg, res, rxlen);
sgs[0] = &req_sg;
sgs[1] = &res_sg;
line->rxlen = 0;
reinit_completion(&line->completion);
/*
* Virtqueue callers need to ensure they don't call its APIs with other
* virtqueue operations at the same time.
*/
mutex_lock(&vgpio->lock);
ret = virtqueue_add_sgs(vgpio->request_vq, sgs, 1, 1, line, GFP_KERNEL);
if (ret) {
dev_err(dev, "failed to add request to vq\n");
mutex_unlock(&vgpio->lock);
goto out;
}
virtqueue_kick(vgpio->request_vq);
mutex_unlock(&vgpio->lock);
wait_for_completion(&line->completion);
if (unlikely(res->status != VIRTIO_GPIO_STATUS_OK)) {
dev_err(dev, "GPIO request failed: %d\n", gpio);
ret = -EINVAL;
goto out;
}
if (unlikely(line->rxlen != rxlen)) {
dev_err(dev, "GPIO operation returned incorrect len (%u : %u)\n",
rxlen, line->rxlen);
ret = -EINVAL;
goto out;
}
if (rxvalue)
*rxvalue = res->value;
out:
mutex_unlock(&line->lock);
return ret;
}
static int virtio_gpio_req(struct virtio_gpio *vgpio, u16 type, u16 gpio,
u8 txvalue, u8 *rxvalue)
{
struct virtio_gpio_line *line = &vgpio->lines[gpio];
struct virtio_gpio_response *res = &line->res;
return _virtio_gpio_req(vgpio, type, gpio, txvalue, rxvalue, res,
sizeof(*res));
}
static void virtio_gpio_free(struct gpio_chip *gc, unsigned int gpio)
{
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
VIRTIO_GPIO_DIRECTION_NONE, NULL);
}
static int virtio_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio)
{
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
u8 direction;
int ret;
ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_DIRECTION, gpio, 0,
&direction);
if (ret)
return ret;
switch (direction) {
case VIRTIO_GPIO_DIRECTION_IN:
return GPIO_LINE_DIRECTION_IN;
case VIRTIO_GPIO_DIRECTION_OUT:
return GPIO_LINE_DIRECTION_OUT;
default:
return -EINVAL;
}
}
static int virtio_gpio_direction_input(struct gpio_chip *gc, unsigned int gpio)
{
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
return virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
VIRTIO_GPIO_DIRECTION_IN, NULL);
}
static int virtio_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio,
int value)
{
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
int ret;
ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_VALUE, gpio, value, NULL);
if (ret)
return ret;
return virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_DIRECTION, gpio,
VIRTIO_GPIO_DIRECTION_OUT, NULL);
}
static int virtio_gpio_get(struct gpio_chip *gc, unsigned int gpio)
{
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
u8 value;
int ret;
ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_VALUE, gpio, 0, &value);
return ret ? ret : value;
}
static void virtio_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
{
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_SET_VALUE, gpio, value, NULL);
}
/* Interrupt handling */
static void virtio_gpio_irq_prepare(struct virtio_gpio *vgpio, u16 gpio)
{
struct vgpio_irq_line *irq_line = &vgpio->irq_lines[gpio];
struct virtio_gpio_irq_request *ireq = &irq_line->ireq;
struct virtio_gpio_irq_response *ires = &irq_line->ires;
struct scatterlist *sgs[2], req_sg, res_sg;
int ret;
if (WARN_ON(irq_line->queued || irq_line->masked || irq_line->disabled))
return;
ireq->gpio = cpu_to_le16(gpio);
sg_init_one(&req_sg, ireq, sizeof(*ireq));
sg_init_one(&res_sg, ires, sizeof(*ires));
sgs[0] = &req_sg;
sgs[1] = &res_sg;
ret = virtqueue_add_sgs(vgpio->event_vq, sgs, 1, 1, irq_line, GFP_ATOMIC);
if (ret) {
dev_err(&vgpio->vdev->dev, "failed to add request to eventq\n");
return;
}
irq_line->queued = true;
virtqueue_kick(vgpio->event_vq);
}
static void virtio_gpio_irq_enable(struct irq_data *d)
{
struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
raw_spin_lock(&vgpio->eventq_lock);
irq_line->disabled = false;
irq_line->masked = false;
irq_line->queue_pending = true;
raw_spin_unlock(&vgpio->eventq_lock);
irq_line->update_pending = true;
}
static void virtio_gpio_irq_disable(struct irq_data *d)
{
struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
raw_spin_lock(&vgpio->eventq_lock);
irq_line->disabled = true;
irq_line->masked = true;
irq_line->queue_pending = false;
raw_spin_unlock(&vgpio->eventq_lock);
irq_line->update_pending = true;
}
static void virtio_gpio_irq_mask(struct irq_data *d)
{
struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
raw_spin_lock(&vgpio->eventq_lock);
irq_line->masked = true;
raw_spin_unlock(&vgpio->eventq_lock);
}
static void virtio_gpio_irq_unmask(struct irq_data *d)
{
struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
raw_spin_lock(&vgpio->eventq_lock);
irq_line->masked = false;
/* Queue the buffer unconditionally on unmask */
virtio_gpio_irq_prepare(vgpio, d->hwirq);
raw_spin_unlock(&vgpio->eventq_lock);
}
static int virtio_gpio_irq_set_type(struct irq_data *d, unsigned int type)
{
struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
switch (type) {
case IRQ_TYPE_EDGE_RISING:
type = VIRTIO_GPIO_IRQ_TYPE_EDGE_RISING;
break;
case IRQ_TYPE_EDGE_FALLING:
type = VIRTIO_GPIO_IRQ_TYPE_EDGE_FALLING;
break;
case IRQ_TYPE_EDGE_BOTH:
type = VIRTIO_GPIO_IRQ_TYPE_EDGE_BOTH;
break;
case IRQ_TYPE_LEVEL_LOW:
type = VIRTIO_GPIO_IRQ_TYPE_LEVEL_LOW;
break;
case IRQ_TYPE_LEVEL_HIGH:
type = VIRTIO_GPIO_IRQ_TYPE_LEVEL_HIGH;
break;
default:
dev_err(&vgpio->vdev->dev, "unsupported irq type: %u\n", type);
return -EINVAL;
}
irq_line->type = type;
irq_line->update_pending = true;
return 0;
}
static void virtio_gpio_irq_bus_lock(struct irq_data *d)
{
struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
mutex_lock(&vgpio->irq_lock);
}
static void virtio_gpio_irq_bus_sync_unlock(struct irq_data *d)
{
struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
struct virtio_gpio *vgpio = gpiochip_get_data(gc);
struct vgpio_irq_line *irq_line = &vgpio->irq_lines[d->hwirq];
u8 type = irq_line->disabled ? VIRTIO_GPIO_IRQ_TYPE_NONE : irq_line->type;
unsigned long flags;
if (irq_line->update_pending) {
irq_line->update_pending = false;
virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_IRQ_TYPE, d->hwirq, type,
NULL);
/* Queue the buffer only after interrupt is enabled */
raw_spin_lock_irqsave(&vgpio->eventq_lock, flags);
if (irq_line->queue_pending) {
irq_line->queue_pending = false;
virtio_gpio_irq_prepare(vgpio, d->hwirq);
}
raw_spin_unlock_irqrestore(&vgpio->eventq_lock, flags);
}
mutex_unlock(&vgpio->irq_lock);
}
static struct irq_chip vgpio_irq_chip = {
.name = "virtio-gpio",
.irq_enable = virtio_gpio_irq_enable,
.irq_disable = virtio_gpio_irq_disable,
.irq_mask = virtio_gpio_irq_mask,
.irq_unmask = virtio_gpio_irq_unmask,
.irq_set_type = virtio_gpio_irq_set_type,
/* These are required to implement irqchip for slow busses */
.irq_bus_lock = virtio_gpio_irq_bus_lock,
.irq_bus_sync_unlock = virtio_gpio_irq_bus_sync_unlock,
};
static bool ignore_irq(struct virtio_gpio *vgpio, int gpio,
struct vgpio_irq_line *irq_line)
{
bool ignore = false;
raw_spin_lock(&vgpio->eventq_lock);
irq_line->queued = false;
/* Interrupt is disabled currently */
if (irq_line->masked || irq_line->disabled) {
ignore = true;
goto unlock;
}
/*
* Buffer is returned as the interrupt was disabled earlier, but is
* enabled again now. Requeue the buffers.
*/
if (irq_line->ires.status == VIRTIO_GPIO_IRQ_STATUS_INVALID) {
virtio_gpio_irq_prepare(vgpio, gpio);
ignore = true;
goto unlock;
}
if (WARN_ON(irq_line->ires.status != VIRTIO_GPIO_IRQ_STATUS_VALID))
ignore = true;
unlock:
raw_spin_unlock(&vgpio->eventq_lock);
return ignore;
}
static void virtio_gpio_event_vq(struct virtqueue *vq)
{
struct virtio_gpio *vgpio = vq->vdev->priv;
struct device *dev = &vgpio->vdev->dev;
struct vgpio_irq_line *irq_line;
int gpio, ret;
unsigned int len;
while (true) {
irq_line = virtqueue_get_buf(vgpio->event_vq, &len);
if (!irq_line)
break;
if (len != sizeof(irq_line->ires)) {
dev_err(dev, "irq with incorrect length (%u : %u)\n",
len, (unsigned int)sizeof(irq_line->ires));
continue;
}
/*
* Find GPIO line number from the offset of irq_line within the
* irq_lines block. We can also get GPIO number from
* irq-request, but better not to rely on a buffer returned by
* remote.
*/
gpio = irq_line - vgpio->irq_lines;
WARN_ON(gpio >= vgpio->gc.ngpio);
if (unlikely(ignore_irq(vgpio, gpio, irq_line)))
continue;
ret = generic_handle_domain_irq(vgpio->gc.irq.domain, gpio);
if (ret)
dev_err(dev, "failed to handle interrupt: %d\n", ret);
}
}
static void virtio_gpio_request_vq(struct virtqueue *vq)
{
struct virtio_gpio_line *line;
unsigned int len;
do {
line = virtqueue_get_buf(vq, &len);
if (!line)
return;
line->rxlen = len;
complete(&line->completion);
} while (1);
}
static void virtio_gpio_free_vqs(struct virtio_device *vdev)
{
virtio_reset_device(vdev);
vdev->config->del_vqs(vdev);
}
static int virtio_gpio_alloc_vqs(struct virtio_gpio *vgpio,
struct virtio_device *vdev)
{
const char * const names[] = { "requestq", "eventq" };
vq_callback_t *cbs[] = {
virtio_gpio_request_vq,
virtio_gpio_event_vq,
};
struct virtqueue *vqs[2] = { NULL, NULL };
int ret;
ret = virtio_find_vqs(vdev, vgpio->irq_lines ? 2 : 1, vqs, cbs, names, NULL);
if (ret) {
dev_err(&vdev->dev, "failed to find vqs: %d\n", ret);
return ret;
}
if (!vqs[0]) {
dev_err(&vdev->dev, "failed to find requestq vq\n");
goto out;
}
vgpio->request_vq = vqs[0];
if (vgpio->irq_lines && !vqs[1]) {
dev_err(&vdev->dev, "failed to find eventq vq\n");
goto out;
}
vgpio->event_vq = vqs[1];
return 0;
out:
if (vqs[0] || vqs[1])
virtio_gpio_free_vqs(vdev);
return -ENODEV;
}
static const char **virtio_gpio_get_names(struct virtio_gpio *vgpio,
u32 gpio_names_size, u16 ngpio)
{
struct virtio_gpio_response_get_names *res;
struct device *dev = &vgpio->vdev->dev;
u8 *gpio_names, *str;
const char **names;
int i, ret, len;
if (!gpio_names_size)
return NULL;
len = sizeof(*res) + gpio_names_size;
res = devm_kzalloc(dev, len, GFP_KERNEL);
if (!res)
return NULL;
gpio_names = res->value;
ret = _virtio_gpio_req(vgpio, VIRTIO_GPIO_MSG_GET_NAMES, 0, 0, NULL,
res, len);
if (ret) {
dev_err(dev, "Failed to get GPIO names: %d\n", ret);
return NULL;
}
names = devm_kcalloc(dev, ngpio, sizeof(*names), GFP_KERNEL);
if (!names)
return NULL;
/* NULL terminate the string instead of checking it */
gpio_names[gpio_names_size - 1] = '\0';
for (i = 0, str = gpio_names; i < ngpio; i++) {
names[i] = str;
str += strlen(str) + 1; /* zero-length strings are allowed */
if (str > gpio_names + gpio_names_size) {
dev_err(dev, "gpio_names block is too short (%d)\n", i);
return NULL;
}
}
return names;
}
static int virtio_gpio_probe(struct virtio_device *vdev)
{
struct virtio_gpio_config config;
struct device *dev = &vdev->dev;
struct virtio_gpio *vgpio;
u32 gpio_names_size;
u16 ngpio;
int ret, i;
vgpio = devm_kzalloc(dev, sizeof(*vgpio), GFP_KERNEL);
if (!vgpio)
return -ENOMEM;
/* Read configuration */
virtio_cread_bytes(vdev, 0, &config, sizeof(config));
gpio_names_size = le32_to_cpu(config.gpio_names_size);
ngpio = le16_to_cpu(config.ngpio);
if (!ngpio) {
dev_err(dev, "Number of GPIOs can't be zero\n");
return -EINVAL;
}
vgpio->lines = devm_kcalloc(dev, ngpio, sizeof(*vgpio->lines), GFP_KERNEL);
if (!vgpio->lines)
return -ENOMEM;
for (i = 0; i < ngpio; i++) {
mutex_init(&vgpio->lines[i].lock);
init_completion(&vgpio->lines[i].completion);
}
mutex_init(&vgpio->lock);
vdev->priv = vgpio;
vgpio->vdev = vdev;
vgpio->gc.free = virtio_gpio_free;
vgpio->gc.get_direction = virtio_gpio_get_direction;
vgpio->gc.direction_input = virtio_gpio_direction_input;
vgpio->gc.direction_output = virtio_gpio_direction_output;
vgpio->gc.get = virtio_gpio_get;
vgpio->gc.set = virtio_gpio_set;
vgpio->gc.ngpio = ngpio;
vgpio->gc.base = -1; /* Allocate base dynamically */
vgpio->gc.label = dev_name(dev);
vgpio->gc.parent = dev;
vgpio->gc.owner = THIS_MODULE;
vgpio->gc.can_sleep = true;
/* Interrupt support */
if (virtio_has_feature(vdev, VIRTIO_GPIO_F_IRQ)) {
vgpio->irq_lines = devm_kcalloc(dev, ngpio, sizeof(*vgpio->irq_lines), GFP_KERNEL);
if (!vgpio->irq_lines)
return -ENOMEM;
/* The event comes from the outside so no parent handler */
vgpio->gc.irq.parent_handler = NULL;
vgpio->gc.irq.num_parents = 0;
vgpio->gc.irq.parents = NULL;
vgpio->gc.irq.default_type = IRQ_TYPE_NONE;
vgpio->gc.irq.handler = handle_level_irq;
vgpio->gc.irq.chip = &vgpio_irq_chip;
for (i = 0; i < ngpio; i++) {
vgpio->irq_lines[i].type = VIRTIO_GPIO_IRQ_TYPE_NONE;
vgpio->irq_lines[i].disabled = true;
vgpio->irq_lines[i].masked = true;
}
mutex_init(&vgpio->irq_lock);
raw_spin_lock_init(&vgpio->eventq_lock);
}
ret = virtio_gpio_alloc_vqs(vgpio, vdev);
if (ret)
return ret;
/* Mark the device ready to perform operations from within probe() */
virtio_device_ready(vdev);
vgpio->gc.names = virtio_gpio_get_names(vgpio, gpio_names_size, ngpio);
ret = gpiochip_add_data(&vgpio->gc, vgpio);
if (ret) {
virtio_gpio_free_vqs(vdev);
dev_err(dev, "Failed to add virtio-gpio controller\n");
}
return ret;
}
static void virtio_gpio_remove(struct virtio_device *vdev)
{
struct virtio_gpio *vgpio = vdev->priv;
gpiochip_remove(&vgpio->gc);
virtio_gpio_free_vqs(vdev);
}
static const struct virtio_device_id id_table[] = {
{ VIRTIO_ID_GPIO, VIRTIO_DEV_ANY_ID },
{},
};
MODULE_DEVICE_TABLE(virtio, id_table);
static const unsigned int features[] = {
VIRTIO_GPIO_F_IRQ,
};
static struct virtio_driver virtio_gpio_driver = {
.feature_table = features,
.feature_table_size = ARRAY_SIZE(features),
.id_table = id_table,
.probe = virtio_gpio_probe,
.remove = virtio_gpio_remove,
.driver = {
.name = KBUILD_MODNAME,
.owner = THIS_MODULE,
},
};
module_virtio_driver(virtio_gpio_driver);
MODULE_AUTHOR("Enrico Weigelt, metux IT consult <info@metux.net>");
MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
MODULE_DESCRIPTION("VirtIO GPIO driver");
MODULE_LICENSE("GPL");