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-rw-r--r--drivers/gnss/Kconfig11
-rw-r--r--drivers/gnss/Makefile7
-rw-r--r--drivers/gnss/core.c371
3 files changed, 389 insertions, 0 deletions
diff --git a/drivers/gnss/Kconfig b/drivers/gnss/Kconfig
new file mode 100644
index 000000000000..103fcc70992e
--- /dev/null
+++ b/drivers/gnss/Kconfig
@@ -0,0 +1,11 @@
+#
+# GNSS receiver configuration
+#
+
+menuconfig GNSS
+ tristate "GNSS receiver support"
+ ---help---
+ Say Y here if you have a GNSS receiver (e.g. a GPS receiver).
+
+ To compile this driver as a module, choose M here: the module will
+ be called gnss.
diff --git a/drivers/gnss/Makefile b/drivers/gnss/Makefile
new file mode 100644
index 000000000000..1f7a7baab1d9
--- /dev/null
+++ b/drivers/gnss/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the GNSS subsystem.
+#
+
+obj-$(CONFIG_GNSS) += gnss.o
+gnss-y := core.o
diff --git a/drivers/gnss/core.c b/drivers/gnss/core.c
new file mode 100644
index 000000000000..307894ca2725
--- /dev/null
+++ b/drivers/gnss/core.c
@@ -0,0 +1,371 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * GNSS receiver core
+ *
+ * Copyright (C) 2018 Johan Hovold <johan@kernel.org>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cdev.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/gnss.h>
+#include <linux/idr.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/poll.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+#include <linux/wait.h>
+
+#define GNSS_FLAG_HAS_WRITE_RAW BIT(0)
+
+#define GNSS_MINORS 16
+
+static DEFINE_IDA(gnss_minors);
+static dev_t gnss_first;
+
+/* FIFO size must be a power of two */
+#define GNSS_READ_FIFO_SIZE 4096
+#define GNSS_WRITE_BUF_SIZE 1024
+
+#define to_gnss_device(d) container_of((d), struct gnss_device, dev)
+
+static int gnss_open(struct inode *inode, struct file *file)
+{
+ struct gnss_device *gdev;
+ int ret = 0;
+
+ gdev = container_of(inode->i_cdev, struct gnss_device, cdev);
+
+ get_device(&gdev->dev);
+
+ nonseekable_open(inode, file);
+ file->private_data = gdev;
+
+ down_write(&gdev->rwsem);
+ if (gdev->disconnected) {
+ ret = -ENODEV;
+ goto unlock;
+ }
+
+ if (gdev->count++ == 0) {
+ ret = gdev->ops->open(gdev);
+ if (ret)
+ gdev->count--;
+ }
+unlock:
+ up_write(&gdev->rwsem);
+
+ if (ret)
+ put_device(&gdev->dev);
+
+ return ret;
+}
+
+static int gnss_release(struct inode *inode, struct file *file)
+{
+ struct gnss_device *gdev = file->private_data;
+
+ down_write(&gdev->rwsem);
+ if (gdev->disconnected)
+ goto unlock;
+
+ if (--gdev->count == 0) {
+ gdev->ops->close(gdev);
+ kfifo_reset(&gdev->read_fifo);
+ }
+unlock:
+ up_write(&gdev->rwsem);
+
+ put_device(&gdev->dev);
+
+ return 0;
+}
+
+static ssize_t gnss_read(struct file *file, char __user *buf,
+ size_t count, loff_t *pos)
+{
+ struct gnss_device *gdev = file->private_data;
+ unsigned int copied;
+ int ret;
+
+ mutex_lock(&gdev->read_mutex);
+ while (kfifo_is_empty(&gdev->read_fifo)) {
+ mutex_unlock(&gdev->read_mutex);
+
+ if (gdev->disconnected)
+ return 0;
+
+ if (file->f_flags & O_NONBLOCK)
+ return -EAGAIN;
+
+ ret = wait_event_interruptible(gdev->read_queue,
+ gdev->disconnected ||
+ !kfifo_is_empty(&gdev->read_fifo));
+ if (ret)
+ return -ERESTARTSYS;
+
+ mutex_lock(&gdev->read_mutex);
+ }
+
+ ret = kfifo_to_user(&gdev->read_fifo, buf, count, &copied);
+ if (ret == 0)
+ ret = copied;
+
+ mutex_unlock(&gdev->read_mutex);
+
+ return ret;
+}
+
+static ssize_t gnss_write(struct file *file, const char __user *buf,
+ size_t count, loff_t *pos)
+{
+ struct gnss_device *gdev = file->private_data;
+ size_t written = 0;
+ int ret;
+
+ if (gdev->disconnected)
+ return -EIO;
+
+ if (!count)
+ return 0;
+
+ if (!(gdev->flags & GNSS_FLAG_HAS_WRITE_RAW))
+ return -EIO;
+
+ /* Ignoring O_NONBLOCK, write_raw() is synchronous. */
+
+ ret = mutex_lock_interruptible(&gdev->write_mutex);
+ if (ret)
+ return -ERESTARTSYS;
+
+ for (;;) {
+ size_t n = count - written;
+
+ if (n > GNSS_WRITE_BUF_SIZE)
+ n = GNSS_WRITE_BUF_SIZE;
+
+ if (copy_from_user(gdev->write_buf, buf, n)) {
+ ret = -EFAULT;
+ goto out_unlock;
+ }
+
+ /*
+ * Assumes write_raw can always accept GNSS_WRITE_BUF_SIZE
+ * bytes.
+ *
+ * FIXME: revisit
+ */
+ down_read(&gdev->rwsem);
+ if (!gdev->disconnected)
+ ret = gdev->ops->write_raw(gdev, gdev->write_buf, n);
+ else
+ ret = -EIO;
+ up_read(&gdev->rwsem);
+
+ if (ret < 0)
+ break;
+
+ written += ret;
+ buf += ret;
+
+ if (written == count)
+ break;
+ }
+
+ if (written)
+ ret = written;
+out_unlock:
+ mutex_unlock(&gdev->write_mutex);
+
+ return ret;
+}
+
+static __poll_t gnss_poll(struct file *file, poll_table *wait)
+{
+ struct gnss_device *gdev = file->private_data;
+ __poll_t mask = 0;
+
+ poll_wait(file, &gdev->read_queue, wait);
+
+ if (!kfifo_is_empty(&gdev->read_fifo))
+ mask |= EPOLLIN | EPOLLRDNORM;
+ if (gdev->disconnected)
+ mask |= EPOLLHUP;
+
+ return mask;
+}
+
+static const struct file_operations gnss_fops = {
+ .owner = THIS_MODULE,
+ .open = gnss_open,
+ .release = gnss_release,
+ .read = gnss_read,
+ .write = gnss_write,
+ .poll = gnss_poll,
+ .llseek = no_llseek,
+};
+
+static struct class *gnss_class;
+
+static void gnss_device_release(struct device *dev)
+{
+ struct gnss_device *gdev = to_gnss_device(dev);
+
+ kfree(gdev->write_buf);
+ kfifo_free(&gdev->read_fifo);
+ ida_simple_remove(&gnss_minors, gdev->id);
+ kfree(gdev);
+}
+
+struct gnss_device *gnss_allocate_device(struct device *parent)
+{
+ struct gnss_device *gdev;
+ struct device *dev;
+ int id;
+ int ret;
+
+ gdev = kzalloc(sizeof(*gdev), GFP_KERNEL);
+ if (!gdev)
+ return NULL;
+
+ id = ida_simple_get(&gnss_minors, 0, GNSS_MINORS, GFP_KERNEL);
+ if (id < 0) {
+ kfree(gdev);
+ return ERR_PTR(id);
+ }
+
+ gdev->id = id;
+
+ dev = &gdev->dev;
+ device_initialize(dev);
+ dev->devt = gnss_first + id;
+ dev->class = gnss_class;
+ dev->parent = parent;
+ dev->release = gnss_device_release;
+ dev_set_drvdata(dev, gdev);
+ dev_set_name(dev, "gnss%d", id);
+
+ init_rwsem(&gdev->rwsem);
+ mutex_init(&gdev->read_mutex);
+ mutex_init(&gdev->write_mutex);
+ init_waitqueue_head(&gdev->read_queue);
+
+ ret = kfifo_alloc(&gdev->read_fifo, GNSS_READ_FIFO_SIZE, GFP_KERNEL);
+ if (ret)
+ goto err_put_device;
+
+ gdev->write_buf = kzalloc(GNSS_WRITE_BUF_SIZE, GFP_KERNEL);
+ if (!gdev->write_buf)
+ goto err_put_device;
+
+ cdev_init(&gdev->cdev, &gnss_fops);
+ gdev->cdev.owner = THIS_MODULE;
+
+ return gdev;
+
+err_put_device:
+ put_device(dev);
+
+ return ERR_PTR(-ENOMEM);
+}
+EXPORT_SYMBOL_GPL(gnss_allocate_device);
+
+void gnss_put_device(struct gnss_device *gdev)
+{
+ put_device(&gdev->dev);
+}
+EXPORT_SYMBOL_GPL(gnss_put_device);
+
+int gnss_register_device(struct gnss_device *gdev)
+{
+ int ret;
+
+ /* Set a flag which can be accessed without holding the rwsem. */
+ if (gdev->ops->write_raw != NULL)
+ gdev->flags |= GNSS_FLAG_HAS_WRITE_RAW;
+
+ ret = cdev_device_add(&gdev->cdev, &gdev->dev);
+ if (ret) {
+ dev_err(&gdev->dev, "failed to add device: %d\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(gnss_register_device);
+
+void gnss_deregister_device(struct gnss_device *gdev)
+{
+ down_write(&gdev->rwsem);
+ gdev->disconnected = true;
+ if (gdev->count) {
+ wake_up_interruptible(&gdev->read_queue);
+ gdev->ops->close(gdev);
+ }
+ up_write(&gdev->rwsem);
+
+ cdev_device_del(&gdev->cdev, &gdev->dev);
+}
+EXPORT_SYMBOL_GPL(gnss_deregister_device);
+
+/*
+ * Caller guarantees serialisation.
+ *
+ * Must not be called for a closed device.
+ */
+int gnss_insert_raw(struct gnss_device *gdev, const unsigned char *buf,
+ size_t count)
+{
+ int ret;
+
+ ret = kfifo_in(&gdev->read_fifo, buf, count);
+
+ wake_up_interruptible(&gdev->read_queue);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(gnss_insert_raw);
+
+static int __init gnss_module_init(void)
+{
+ int ret;
+
+ ret = alloc_chrdev_region(&gnss_first, 0, GNSS_MINORS, "gnss");
+ if (ret < 0) {
+ pr_err("failed to allocate device numbers: %d\n", ret);
+ return ret;
+ }
+
+ gnss_class = class_create(THIS_MODULE, "gnss");
+ if (IS_ERR(gnss_class)) {
+ ret = PTR_ERR(gnss_class);
+ pr_err("failed to create class: %d\n", ret);
+ goto err_unregister_chrdev;
+ }
+
+ pr_info("GNSS driver registered with major %d\n", MAJOR(gnss_first));
+
+ return 0;
+
+err_unregister_chrdev:
+ unregister_chrdev_region(gnss_first, GNSS_MINORS);
+
+ return ret;
+}
+module_init(gnss_module_init);
+
+static void __exit gnss_module_exit(void)
+{
+ class_destroy(gnss_class);
+ unregister_chrdev_region(gnss_first, GNSS_MINORS);
+ ida_destroy(&gnss_minors);
+}
+module_exit(gnss_module_exit);
+
+MODULE_AUTHOR("Johan Hovold <johan@kernel.org>");
+MODULE_DESCRIPTION("GNSS receiver core");
+MODULE_LICENSE("GPL v2");
generated by cgit v1.2.3 (git 2.39.0) at 2024-11-30 01:43:08 +0300