From: "Enrico Weigelt, metux IT consult" <i...@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" <i...@metux.net>
Co-developed-by: Viresh Kumar <viresh.ku...@linaro.org>
Signed-off-by: Viresh Kumar <viresh.ku...@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 <i...@metux.net>
+ *
+ * Copyright (C) 2021 Linaro.
+ * Viresh Kumar <viresh.ku...@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 <i...@metux.net>");
+MODULE_AUTHOR("Viresh Kumar <viresh.ku...@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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