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// SPDX-License-Identifier: GPL-2.0
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/device.h>
#include <linux/platform_device.h>
#include <linux/cdev.h>
#include <linux/of.h>
struct hello_dev {
struct device *dev;
struct cdev cdev;
unsigned int minor;
};
#define HELLO_MAX_DEVICES 10
static struct class *hello_class;
static dev_t hello_devt;
static int hello_open(struct inode *node, struct file *f)
{
struct cdev *cd = node->i_cdev;
struct hello_dev *hello = container_of(cd, struct hello_dev, cdev);
dev_info(hello->dev, "%s\n", __func__);
f->private_data = hello;
return 0;
}
static int hello_release(struct inode *node, struct file *f)
{
struct hello_dev *hello = f->private_data;
dev_info(hello->dev, "%s\n", __func__);
f->private_data = NULL;
return 0;
}
static ssize_t hello_read(struct file *f, char __user *u, size_t s, loff_t *l)
{
struct hello_dev *hello = f->private_data;
char buf[10];
size_t len;
dev_info(hello->dev, "%s: size=%zu offset=%llu\n", __func__, s, *l);
if (*l >= 40)
return 0;
len = snprintf(buf, sizeof(buf), "hello:%d\n", hello->minor);
if (s < len)
len = s;
if (copy_to_user(u, buf, len) != 0)
return -EFAULT;
*l += len;
return len;
}
static ssize_t hello_write(struct file *f, const char __user *u, size_t s,
loff_t *l)
{
struct hello_dev *hello = f->private_data;
dev_info(hello->dev, "%s: size=%zu offset=%llu\n", __func__, s, *l);
return s;
}
static const struct file_operations hello_fops = {
.owner = THIS_MODULE,
.open = hello_open,
.release = hello_release,
.read = hello_read,
.write = hello_write,
};
static int hello_probe(struct platform_device *pdev)
{
struct hello_dev *hello;
struct device *dev;
dev_t devt;
int ret;
hello = devm_kzalloc(&pdev->dev, sizeof(*hello), GFP_KERNEL);
if (!hello) {
dev_err(&pdev->dev, "devm_kzalloc failed\n");
return -ENOMEM;
}
#ifdef CONFIG_OF
ret = of_property_read_u32(pdev->dev.of_node, "index", &hello->minor);
if (ret < 0) {
dev_err(&pdev->dev, "no index specified\n");
goto err_out;
}
#else
hello->minor = (unsigned)pdev->id;
#endif
if (hello->minor >= HELLO_MAX_DEVICES) {
dev_err(&pdev->dev, "invalid index: %u\n", hello->minor);
ret = -EINVAL;
goto err_out;
}
hello->dev = &pdev->dev;
platform_set_drvdata(pdev, hello);
devt = MKDEV(MAJOR(hello_devt), hello->minor);
cdev_init(&hello->cdev, &hello_fops);
hello->cdev.owner = THIS_MODULE;
ret = cdev_add(&hello->cdev, devt, 1);
if (ret != 0) {
dev_err(&pdev->dev, "cdev_add failed\n");
goto err_drvdata;
}
dev = device_create(hello_class, &pdev->dev, devt, hello,
"hello%d", hello->minor);
if (IS_ERR(dev)) {
dev_err(&pdev->dev, "device_create failed\n");
ret = PTR_ERR(dev);
goto err_cdev;
}
dev_info(&pdev->dev, "HELLO! I am hello device %d!\n", hello->minor);
return 0;
err_cdev:
cdev_del(&hello->cdev);
err_drvdata:
platform_set_drvdata(pdev, NULL);
err_out:
return ret;
}
static int hello_remove(struct platform_device *pdev)
{
struct hello_dev *hello = platform_get_drvdata(pdev);
device_destroy(hello_class, MKDEV(MAJOR(hello_devt), hello->minor));
cdev_del(&hello->cdev);
platform_set_drvdata(pdev, NULL);
dev_info(&pdev->dev, "GOODBYE! I was hello device %d!\n", hello->minor);
return 0;
}
static const struct of_device_id hello_match[] = {
{ .compatible = "virtual,hello", },
{ /* end of table */ }
};
static struct platform_driver hello_driver = {
.driver = {
.name = "hello",
.of_match_table = hello_match,
},
.probe = hello_probe,
.remove = hello_remove,
};
#ifndef CONFIG_OF
static struct platform_device *pdevs[3];
#endif
static int __init hello_init(void)
{
int ret;
printk(KERN_INFO "%s\n", __func__);
ret = alloc_chrdev_region(&hello_devt, 0, HELLO_MAX_DEVICES, "hello");
if (ret < 0)
return ret;
hello_class = class_create(THIS_MODULE, "hello");
if (IS_ERR(hello_class)) {
printk(KERN_ERR "%s: failed to create class\n", __func__);
ret = PTR_ERR(hello_class);
goto err_region;
}
ret = platform_driver_register(&hello_driver);
if (ret != 0)
goto err_class;
#ifndef CONFIG_OF
pdevs[0] = platform_device_register_simple("hello", 1, NULL, 0);
pdevs[1] = platform_device_register_simple("hello", 3, NULL, 0);
pdevs[2] = platform_device_register_simple("hello", 5, NULL, 0);
#endif
return 0;
err_class:
class_destroy(hello_class);
err_region:
unregister_chrdev_region(hello_devt, HELLO_MAX_DEVICES);
return ret;
}
static void __exit hello_exit(void)
{
printk(KERN_INFO "%s\n", __func__);
#ifndef CONFIG_OF
platform_device_unregister(pdevs[0]);
platform_device_unregister(pdevs[1]);
platform_device_unregister(pdevs[2]);
#endif
platform_driver_unregister(&hello_driver);
class_destroy(hello_class);
unregister_chrdev_region(hello_devt, HELLO_MAX_DEVICES);
}
module_init(hello_init);
module_exit(hello_exit);
MODULE_AUTHOR("John Ogness <john.ogness@linutronix.de>");
MODULE_DESCRIPTION("a great module for hello-ing!");
MODULE_LICENSE("GPL v2");
MODULE_VERSION("20190101");
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