From d2d7aa53891ea11c8ba9357c75bf1d784e57e0ba Mon Sep 17 00:00:00 2001 From: Greg Kroah-Hartman Date: Tue, 7 Sep 2021 13:40:44 +0200 Subject: [PATCH] staging: axis-fifo: convert to use miscdevice Using a struct class, a cdev, and another device just for a single minor device is total overkill. Just use a dynamic misc device instead, saving lots of logic and memory. Cc: Jacob Feder Cc: Lee Jones Cc: Muhammad Usama Anjum Link: https://lore.kernel.org/r/YTdPvBgKW6cKYrvb@kroah.com Signed-off-by: Greg Kroah-Hartman --- drivers/staging/axis-fifo/axis-fifo.c | 88 +++++++++++------------------------ 1 file changed, 26 insertions(+), 62 deletions(-) diff --git a/drivers/staging/axis-fifo/axis-fifo.c b/drivers/staging/axis-fifo/axis-fifo.c index b23eabb..632f140 100644 --- a/drivers/staging/axis-fifo/axis-fifo.c +++ b/drivers/staging/axis-fifo/axis-fifo.c @@ -30,6 +30,7 @@ #include #include #include +#include #include #include @@ -102,9 +103,6 @@ * globals * ---------------------------- */ - -static struct class *axis_fifo_driver_class; /* char device class */ - static int read_timeout = 1000; /* ms to wait before read() times out */ static int write_timeout = 1000; /* ms to wait before write() times out */ @@ -140,9 +138,7 @@ struct axis_fifo { unsigned int read_flags; /* read file flags */ struct device *dt_device; /* device created from the device tree */ - struct device *device; /* device associated with char_device */ - dev_t devt; /* our char device number */ - struct cdev char_device; /* our char device */ + struct miscdevice miscdev; }; /* ---------------------------- @@ -319,6 +315,11 @@ static const struct attribute_group axis_fifo_attrs_group = { .attrs = axis_fifo_attrs, }; +static const struct attribute_group *axis_fifo_attrs_groups[] = { + &axis_fifo_attrs_group, + NULL, +}; + /* ---------------------------- * implementation * ---------------------------- @@ -684,8 +685,8 @@ static irqreturn_t axis_fifo_irq(int irq, void *dw) static int axis_fifo_open(struct inode *inod, struct file *f) { - struct axis_fifo *fifo = (struct axis_fifo *)container_of(inod->i_cdev, - struct axis_fifo, char_device); + struct axis_fifo *fifo = container_of(f->private_data, + struct axis_fifo, miscdev); f->private_data = fifo; if (((f->f_flags & O_ACCMODE) == O_WRONLY) || @@ -812,9 +813,7 @@ static int axis_fifo_probe(struct platform_device *pdev) struct resource *r_mem; /* IO mem resources */ struct device *dev = &pdev->dev; /* OS device (from device tree) */ struct axis_fifo *fifo = NULL; - - char device_name[32]; - + char *device_name; int rc = 0; /* error return value */ /* ---------------------------- @@ -822,8 +821,12 @@ static int axis_fifo_probe(struct platform_device *pdev) * ---------------------------- */ + device_name = devm_kzalloc(dev, 32, GFP_KERNEL); + if (!device_name) + return -ENOMEM; + /* allocate device wrapper memory */ - fifo = devm_kmalloc(dev, sizeof(*fifo), GFP_KERNEL); + fifo = devm_kzalloc(dev, sizeof(*fifo), GFP_KERNEL); if (!fifo) return -ENOMEM; @@ -859,9 +862,7 @@ static int axis_fifo_probe(struct platform_device *pdev) dev_dbg(fifo->dt_device, "remapped memory to 0x%p\n", fifo->base_addr); /* create unique device name */ - snprintf(device_name, sizeof(device_name), "%s_%pa", - DRIVER_NAME, &r_mem->start); - + snprintf(device_name, 32, "%s_%pa", DRIVER_NAME, &r_mem->start); dev_dbg(fifo->dt_device, "device name [%s]\n", device_name); /* ---------------------------- @@ -904,51 +905,21 @@ static int axis_fifo_probe(struct platform_device *pdev) * ---------------------------- */ - /* allocate device number */ - rc = alloc_chrdev_region(&fifo->devt, 0, 1, DRIVER_NAME); + /* create character device */ + fifo->miscdev.fops = &fops; + fifo->miscdev.minor = MISC_DYNAMIC_MINOR; + fifo->miscdev.name = device_name; + fifo->miscdev.groups = axis_fifo_attrs_groups; + fifo->miscdev.parent = dev; + rc = misc_register(&fifo->miscdev); if (rc < 0) goto err_initial; - dev_dbg(fifo->dt_device, "allocated device number major %i minor %i\n", - MAJOR(fifo->devt), MINOR(fifo->devt)); - - /* create driver file */ - fifo->device = device_create(axis_fifo_driver_class, NULL, fifo->devt, - NULL, device_name); - if (IS_ERR(fifo->device)) { - dev_err(fifo->dt_device, - "couldn't create driver file\n"); - rc = PTR_ERR(fifo->device); - goto err_chrdev_region; - } - dev_set_drvdata(fifo->device, fifo); - - /* create character device */ - cdev_init(&fifo->char_device, &fops); - rc = cdev_add(&fifo->char_device, fifo->devt, 1); - if (rc < 0) { - dev_err(fifo->dt_device, "couldn't create character device\n"); - goto err_dev; - } - - /* create sysfs entries */ - rc = devm_device_add_group(fifo->device, &axis_fifo_attrs_group); - if (rc < 0) { - dev_err(fifo->dt_device, "couldn't register sysfs group\n"); - goto err_cdev; - } - dev_info(fifo->dt_device, "axis-fifo created at %pa mapped to 0x%pa, irq=%i, major=%i, minor=%i\n", - &r_mem->start, &fifo->base_addr, fifo->irq, - MAJOR(fifo->devt), MINOR(fifo->devt)); + dev_info(fifo->dt_device, "axis-fifo created at %pa mapped to 0x%pa, irq=%i\n", + &r_mem->start, &fifo->base_addr, fifo->irq); return 0; -err_cdev: - cdev_del(&fifo->char_device); -err_dev: - device_destroy(axis_fifo_driver_class, fifo->devt); -err_chrdev_region: - unregister_chrdev_region(fifo->devt, 1); err_initial: dev_set_drvdata(dev, NULL); return rc; @@ -959,10 +930,7 @@ static int axis_fifo_remove(struct platform_device *pdev) struct device *dev = &pdev->dev; struct axis_fifo *fifo = dev_get_drvdata(dev); - cdev_del(&fifo->char_device); - dev_set_drvdata(fifo->device, NULL); - device_destroy(axis_fifo_driver_class, fifo->devt); - unregister_chrdev_region(fifo->devt, 1); + misc_deregister(&fifo->miscdev); dev_set_drvdata(dev, NULL); return 0; @@ -987,9 +955,6 @@ static int __init axis_fifo_init(void) { pr_info("axis-fifo driver loaded with parameters read_timeout = %i, write_timeout = %i\n", read_timeout, write_timeout); - axis_fifo_driver_class = class_create(THIS_MODULE, DRIVER_NAME); - if (IS_ERR(axis_fifo_driver_class)) - return PTR_ERR(axis_fifo_driver_class); return platform_driver_register(&axis_fifo_driver); } @@ -998,7 +963,6 @@ module_init(axis_fifo_init); static void __exit axis_fifo_exit(void) { platform_driver_unregister(&axis_fifo_driver); - class_destroy(axis_fifo_driver_class); } module_exit(axis_fifo_exit); -- 2.7.4