diff -urNp a/drivers/char/hello.c b/drivers/char/hello.c --- a/drivers/char/hello.c 1970-01-01 01:00:00.000000000 +0100 +++ b/drivers/char/hello.c 2016-06-08 20:46:01.991211855 +0200 @@ -0,0 +1,235 @@ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +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 ssize_t major_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + return sprintf(buf, "%d\n", MAJOR(hello_devt)); +} +static DEVICE_ATTR_RO(major); + +static ssize_t minor_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + struct platform_device *pdev = to_platform_device(dev); + struct hello_dev *hello = platform_get_drvdata(pdev); + + return sprintf(buf, "%d\n", hello->minor); +} +static DEVICE_ATTR_RO(minor); + +static struct attribute *hello_device_attrs[] = { + &dev_attr_major.attr, + &dev_attr_minor.attr, + NULL, +}; +ATTRIBUTE_GROUPS(hello_device); + +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; + } + + 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_out1; + } + + if (hello->minor >= HELLO_MAX_DEVICES) { + dev_err(&pdev->dev, "invalid index: %u\n", hello->minor); + ret = -EINVAL; + goto err_out1; + } + + 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_out1; + } + + 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_out2; + } + + dev_info(&pdev->dev, "HELLO! I am hello device %d!\n", hello->minor); + + return 0; + +err_out2: + cdev_del(&hello->cdev); +err_out1: + platform_set_drvdata(pdev, NULL); + 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", + .owner = THIS_MODULE, + .of_match_table = hello_match, + }, + .probe = hello_probe, + .remove = hello_remove, +}; + +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_out1; + } + + hello_class->dev_groups = hello_device_groups; + + ret = platform_driver_register(&hello_driver); + if (ret != 0) + goto err_out2; + + return 0; + +err_out2: + class_destroy(hello_class); +err_out1: + unregister_chrdev_region(hello_devt, HELLO_MAX_DEVICES); + return ret; +} + +static void __exit hello_exit(void) +{ + printk(KERN_INFO "%s\n", __func__); + + 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 "); +MODULE_DESCRIPTION("a great module for hello-ing!"); +MODULE_LICENSE("GPL v2"); +MODULE_VERSION("20160608"); diff -urNp a/drivers/char/Kconfig b/drivers/char/Kconfig --- a/drivers/char/Kconfig 2016-05-16 00:43:13.000000000 +0200 +++ b/drivers/char/Kconfig 2016-06-08 20:41:14.047205734 +0200 @@ -6,6 +6,16 @@ menu "Character devices" source "drivers/tty/Kconfig" +config HELLO + tristate "hello demo driver" + default n + help + This driver demonstrates how to create a platform device that is + specified in a device tree. + + It also create a character device to demonstrate how a character + device interface can be provided to userspace. + config DEVMEM bool "/dev/mem virtual device support" default y diff -urNp a/drivers/char/Makefile b/drivers/char/Makefile --- a/drivers/char/Makefile 2016-05-16 00:43:13.000000000 +0200 +++ b/drivers/char/Makefile 2016-06-08 14:16:44.897437533 +0200 @@ -16,6 +16,8 @@ obj-$(CONFIG_IBM_BSR) += bsr.o obj-$(CONFIG_SGI_MBCS) += mbcs.o obj-$(CONFIG_BFIN_OTP) += bfin-otp.o +obj-$(CONFIG_HELLO) += hello.o + obj-$(CONFIG_PRINTER) += lp.o obj-$(CONFIG_APM_EMULATION) += apm-emulation.o