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    Subject[PATCH V3 1/3] gpio: Add virtio-gpio driver
    Date
    From: "Enrico Weigelt, metux IT consult" <info@metux.net>

    This patch adds a new driver for Virtio based GPIO devices.

    This allows a guest VM running Linux to access GPIO device provided by
    the host. It supports all basic operations for now, except interrupts
    for the GPIO lines.

    Signed-off-by: "Enrico Weigelt, metux IT consult" <info@metux.net>
    Co-developed-by: Viresh Kumar <viresh.kumar@linaro.org>
    Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
    ---
    drivers/gpio/Kconfig | 9 +
    drivers/gpio/Makefile | 1 +
    drivers/gpio/gpio-virtio.c | 326 +++++++++++++++++++++++++++++++
    include/uapi/linux/virtio_gpio.h | 41 ++++
    include/uapi/linux/virtio_ids.h | 1 +
    5 files changed, 378 insertions(+)
    create mode 100644 drivers/gpio/gpio-virtio.c
    create mode 100644 include/uapi/linux/virtio_gpio.h

    diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
    index e3607ec4c2e8..7f12fb65d130 100644
    --- a/drivers/gpio/Kconfig
    +++ b/drivers/gpio/Kconfig
    @@ -1633,6 +1633,15 @@ config GPIO_MOCKUP
    tools/testing/selftests/gpio/gpio-mockup.sh. Reference the usage in
    it.

    +config GPIO_VIRTIO
    + tristate "VirtIO GPIO support"
    + depends on VIRTIO
    + help
    + Say Y here to enable guest support for virtio-based GPIO controllers.
    +
    + These virtual GPIOs can be routed to real GPIOs or attached to
    + simulators on the host (like QEMU).
    +
    endmenu

    endif
    diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
    index c58a90a3c3b1..ace004c80871 100644
    --- a/drivers/gpio/Makefile
    +++ b/drivers/gpio/Makefile
    @@ -162,6 +162,7 @@ obj-$(CONFIG_GPIO_UCB1400) += gpio-ucb1400.o
    obj-$(CONFIG_GPIO_UNIPHIER) += gpio-uniphier.o
    obj-$(CONFIG_GPIO_VF610) += gpio-vf610.o
    obj-$(CONFIG_GPIO_VIPERBOARD) += gpio-viperboard.o
    +obj-$(CONFIG_GPIO_VIRTIO) += gpio-virtio.o
    obj-$(CONFIG_GPIO_VISCONTI) += gpio-visconti.o
    obj-$(CONFIG_GPIO_VR41XX) += gpio-vr41xx.o
    obj-$(CONFIG_GPIO_VX855) += gpio-vx855.o
    diff --git a/drivers/gpio/gpio-virtio.c b/drivers/gpio/gpio-virtio.c
    new file mode 100644
    index 000000000000..1ba8ddf4693a
    --- /dev/null
    +++ b/drivers/gpio/gpio-virtio.c
    @@ -0,0 +1,326 @@
    +// 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/virtio_config.h>
    +#include <uapi/linux/virtio_gpio.h>
    +#include <uapi/linux/virtio_ids.h>
    +
    +struct virtio_gpio {
    + struct virtio_device *vdev;
    + struct mutex lock;
    + struct gpio_chip gc;
    +
    + struct completion completion;
    + struct virtqueue *command_vq;
    + struct virtio_gpio_request creq;
    + struct virtio_gpio_response cres;
    +
    + /* This must be kept as the last entry here, hint: gpio_names[0] */
    + struct virtio_gpio_config config;
    +};
    +
    +#define gpio_chip_to_vgpio(chip) container_of(chip, struct virtio_gpio, gc)
    +
    +static int virtio_gpio_req(struct virtio_gpio *vgpio, u16 type, u16 gpio,
    + u8 txdata, u8 *rxdata)
    +{
    + struct virtio_gpio_response *res = &vgpio->cres;
    + struct virtio_gpio_request *req = &vgpio->creq;
    + struct scatterlist *sgs[2], req_sg, res_sg;
    + struct device *dev = &vgpio->vdev->dev;
    + unsigned long time_left;
    + unsigned int len;
    + int ret;
    +
    + req->type = cpu_to_le16(type);
    + req->gpio = cpu_to_le16(gpio);
    + req->data = txdata;
    +
    + sg_init_one(&req_sg, req, sizeof(*req));
    + sg_init_one(&res_sg, res, sizeof(*res));
    + sgs[0] = &req_sg;
    + sgs[1] = &res_sg;
    +
    + mutex_lock(&vgpio->lock);
    + ret = virtqueue_add_sgs(vgpio->command_vq, sgs, 1, 1, res, GFP_KERNEL);
    + if (ret) {
    + dev_err(dev, "failed to add request to vq\n");
    + goto out;
    + }
    +
    + reinit_completion(&vgpio->completion);
    + virtqueue_kick(vgpio->command_vq);
    +
    + time_left = wait_for_completion_timeout(&vgpio->completion, HZ / 10);
    + if (!time_left) {
    + dev_err(dev, "virtio GPIO backend timeout\n");
    + return -ETIMEDOUT;
    + }
    +
    + WARN_ON(res != virtqueue_get_buf(vgpio->command_vq, &len));
    + if (unlikely(res->status != VIRTIO_GPIO_STATUS_OK)) {
    + dev_err(dev, "virtio GPIO request failed: %d\n", gpio);
    + return -EINVAL;
    + }
    +
    + if (rxdata)
    + *rxdata = res->data;
    +
    +out:
    + mutex_unlock(&vgpio->lock);
    +
    + return ret;
    +}
    +
    +static int virtio_gpio_request(struct gpio_chip *gc, unsigned int gpio)
    +{
    + struct virtio_gpio *vgpio = gpio_chip_to_vgpio(gc);
    +
    + return virtio_gpio_req(vgpio, VIRTIO_GPIO_REQ_ACTIVATE, gpio, 0, NULL);
    +}
    +
    +static void virtio_gpio_free(struct gpio_chip *gc, unsigned int gpio)
    +{
    + struct virtio_gpio *vgpio = gpio_chip_to_vgpio(gc);
    +
    + virtio_gpio_req(vgpio, VIRTIO_GPIO_REQ_DEACTIVATE, gpio, 0, NULL);
    +}
    +
    +static int virtio_gpio_get_direction(struct gpio_chip *gc, unsigned int gpio)
    +{
    + struct virtio_gpio *vgpio = gpio_chip_to_vgpio(gc);
    + u8 direction;
    + int ret;
    +
    + ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_REQ_GET_DIRECTION, gpio, 0,
    + &direction);
    + if (ret)
    + return ret;
    +
    + return direction;
    +}
    +
    +static int virtio_gpio_direction_input(struct gpio_chip *gc, unsigned int gpio)
    +{
    + struct virtio_gpio *vgpio = gpio_chip_to_vgpio(gc);
    +
    + return virtio_gpio_req(vgpio, VIRTIO_GPIO_REQ_DIRECTION_IN, gpio, 0,
    + NULL);
    +}
    +
    +static int virtio_gpio_direction_output(struct gpio_chip *gc, unsigned int gpio,
    + int value)
    +{
    + struct virtio_gpio *vgpio = gpio_chip_to_vgpio(gc);
    +
    + return virtio_gpio_req(vgpio, VIRTIO_GPIO_REQ_DIRECTION_OUT, gpio, (u8)
    + value, NULL);
    +}
    +
    +static int virtio_gpio_get(struct gpio_chip *gc, unsigned int gpio)
    +{
    + struct virtio_gpio *vgpio = gpio_chip_to_vgpio(gc);
    + u8 value;
    + int ret;
    +
    + ret = virtio_gpio_req(vgpio, VIRTIO_GPIO_REQ_GET_VALUE, gpio, 0, &value);
    + if (ret)
    + return ret;
    +
    + return value;
    +}
    +
    +static void virtio_gpio_set(struct gpio_chip *gc, unsigned int gpio, int value)
    +{
    + struct virtio_gpio *vgpio = gpio_chip_to_vgpio(gc);
    +
    + virtio_gpio_req(vgpio, VIRTIO_GPIO_REQ_SET_VALUE, gpio, value, NULL);
    +}
    +
    +static void virtio_gpio_command(struct virtqueue *vq)
    +{
    + struct virtio_gpio *vgpio = vq->vdev->priv;
    +
    + complete(&vgpio->completion);
    +}
    +
    +static int virtio_gpio_alloc_vqs(struct virtio_device *vdev)
    +{
    + struct virtio_gpio *vgpio = vdev->priv;
    + const char * const names[] = { "command" };
    + vq_callback_t *cbs[] = {
    + virtio_gpio_command,
    + };
    + 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 allocate vqs: %d\n", ret);
    + return ret;
    + }
    +
    + vgpio->command_vq = vqs[0];
    +
    + /* Mark the device ready to perform operations from within probe() */
    + virtio_device_ready(vgpio->vdev);
    + return 0;
    +}
    +
    +static void virtio_gpio_free_vqs(struct virtio_device *vdev)
    +{
    + vdev->config->reset(vdev);
    + vdev->config->del_vqs(vdev);
    +}
    +
    +static const char **parse_gpio_names(struct virtio_device *vdev,
    + struct virtio_gpio_config *config)
    +{
    + struct device *dev = &vdev->dev;
    + char *str = config->gpio_names;
    + const char **names;
    + int i, len;
    +
    + if (!config->gpio_names_size)
    + return NULL;
    +
    + names = devm_kcalloc(dev, config->ngpio, sizeof(names), GFP_KERNEL);
    + if (!names)
    + return ERR_PTR(-ENOMEM);
    +
    + /* NULL terminate the string instead of checking it */
    + config->gpio_names[config->gpio_names_size - 1] = '\0';
    +
    + for (i = 0; i < config->ngpio; i++) {
    + /*
    + * We have already marked the last byte with '\0'
    + * earlier, this shall be enough here.
    + */
    + if (str == config->gpio_names + config->gpio_names_size) {
    + dev_err(dev, "Invalid gpio_names\n");
    + return ERR_PTR(-EINVAL);
    + }
    +
    + len = strlen(str);
    + if (!len) {
    + dev_err(dev, "Missing GPIO name: %d\n", i);
    + return ERR_PTR(-EINVAL);
    + }
    +
    + names[i] = str;
    + str += len + 1;
    + }
    +
    + 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 size;
    + int ret;
    +
    + virtio_cread(vdev, struct virtio_gpio_config, gpio_names_size, &size);
    + size = cpu_to_le32(size);
    +
    + vgpio = devm_kzalloc(dev, sizeof(*vgpio) + size, GFP_KERNEL);
    + if (!vgpio)
    + return -ENOMEM;
    +
    + config = &vgpio->config;
    +
    + /* Read configuration */
    + virtio_cread_bytes(vdev, 0, config, sizeof(*config) + size);
    +
    + /* NULL terminate the string instead of checking it */
    + config->name[sizeof(config->name) - 1] = '\0';
    + config->ngpio = cpu_to_le16(config->ngpio);
    + config->gpio_names_size = cpu_to_le32(config->gpio_names_size);
    +
    + if (!config->ngpio) {
    + dev_err(dev, "Number of GPIOs can't be zero\n");
    + return -EINVAL;
    + }
    +
    + vgpio->vdev = vdev;
    + vgpio->gc.request = virtio_gpio_request;
    + 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 = config->ngpio;
    + vgpio->gc.base = -1; /* Allocate base dynamically */
    + vgpio->gc.label = config->name[0] ?
    + config->name : dev_name(dev);
    + vgpio->gc.parent = dev;
    + vgpio->gc.owner = THIS_MODULE;
    + vgpio->gc.can_sleep = true;
    + vgpio->gc.names = parse_gpio_names(vdev, config);
    + if (IS_ERR(vgpio->gc.names))
    + return PTR_ERR(vgpio->gc.names);
    +
    + vdev->priv = vgpio;
    + mutex_init(&vgpio->lock);
    + init_completion(&vgpio->completion);
    +
    + ret = virtio_gpio_alloc_vqs(vdev);
    + if (ret)
    + return ret;
    +
    + ret = gpiochip_add(&vgpio->gc);
    + 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 <info@metux.net>");
    +MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
    +MODULE_DESCRIPTION("VirtIO GPIO driver");
    +MODULE_LICENSE("GPL");
    diff --git a/include/uapi/linux/virtio_gpio.h b/include/uapi/linux/virtio_gpio.h
    new file mode 100644
    index 000000000000..e805e33a79cb
    --- /dev/null
    +++ b/include/uapi/linux/virtio_gpio.h
    @@ -0,0 +1,41 @@
    +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
    +
    +#ifndef _LINUX_VIRTIO_GPIO_H
    +#define _LINUX_VIRTIO_GPIO_H
    +
    +#include <linux/types.h>
    +
    +/* Virtio GPIO request types */
    +#define VIRTIO_GPIO_REQ_ACTIVATE 0x01
    +#define VIRTIO_GPIO_REQ_DEACTIVATE 0x02
    +#define VIRTIO_GPIO_REQ_GET_DIRECTION 0x03
    +#define VIRTIO_GPIO_REQ_DIRECTION_IN 0x04
    +#define VIRTIO_GPIO_REQ_DIRECTION_OUT 0x05
    +#define VIRTIO_GPIO_REQ_GET_VALUE 0x06
    +#define VIRTIO_GPIO_REQ_SET_VALUE 0x07
    +
    +/* Possible values of the status field */
    +#define VIRTIO_GPIO_STATUS_OK 0x0
    +#define VIRTIO_GPIO_STATUS_ERR 0x1
    +
    +struct virtio_gpio_config {
    + char name[32];
    + __u16 ngpio;
    + __u16 padding;
    + __u32 gpio_names_size;
    + char gpio_names[0];
    +} __packed;
    +
    +/* Virtio GPIO Request / Response */
    +struct virtio_gpio_request {
    + __u16 type;
    + __u16 gpio;
    + __u8 data;
    +};
    +
    +struct virtio_gpio_response {
    + __u8 status;
    + __u8 data;
    +};
    +
    +#endif /* _LINUX_VIRTIO_GPIO_H */
    diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
    index b89391dff6c9..0c24e8ae2499 100644
    --- a/include/uapi/linux/virtio_ids.h
    +++ b/include/uapi/linux/virtio_ids.h
    @@ -55,5 +55,6 @@
    #define VIRTIO_ID_PMEM 27 /* virtio pmem */
    #define VIRTIO_ID_MAC80211_HWSIM 29 /* virtio mac80211-hwsim */
    #define VIRTIO_ID_I2C_ADAPTER 34 /* virtio i2c adapter */
    +#define VIRTIO_ID_GPIO 41 /* virtio GPIO */

    #endif /* _LINUX_VIRTIO_IDS_H */
    --
    2.31.1.272.g89b43f80a514
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      Last update: 2021-06-10 14:17    [W:4.226 / U:0.148 seconds]
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