forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
374 lines
9.2 KiB
374 lines
9.2 KiB
// 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 <[email protected]> |
|
* |
|
* Copyright (C) 2021 Linaro. |
|
* Viresh Kumar <[email protected]> |
|
*/ |
|
|
|
#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/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 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; |
|
}; |
|
|
|
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); |
|
|
|
if (!wait_for_completion_timeout(&line->completion, HZ)) { |
|
dev_err(dev, "GPIO operation timed out\n"); |
|
ret = -ETIMEDOUT; |
|
goto out; |
|
} |
|
|
|
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); |
|
} |
|
|
|
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) |
|
{ |
|
vdev->config->reset(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" }; |
|
vq_callback_t *cbs[] = { |
|
virtio_gpio_request_vq, |
|
}; |
|
struct virtqueue *vqs[1] = { NULL }; |
|
int ret; |
|
|
|
ret = virtio_find_vqs(vdev, 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"); |
|
return -ENODEV; |
|
} |
|
vgpio->request_vq = vqs[0]; |
|
|
|
return 0; |
|
} |
|
|
|
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; |
|
|
|
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 struct virtio_driver virtio_gpio_driver = { |
|
.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 <[email protected]>"); |
|
MODULE_AUTHOR("Viresh Kumar <[email protected]>"); |
|
MODULE_DESCRIPTION("VirtIO GPIO driver"); |
|
MODULE_LICENSE("GPL");
|
|
|