From 2d46e81d9bbb624695bac8400a4ac41b7f116ec4 Mon Sep 17 00:00:00 2001 From: Jaghathiswari Rankappagounder Natarajan Date: Fri, 27 Jul 2018 12:34:54 -0700 Subject: [PATCH 2/3] drivers: misc: Character device driver for seven segment display Character device driver which implements the user-space API for letting a user write to two 7-segment displays including any conversion methods necessary to map the user input to two 7-segment displays. Signed-off-by: Jaghathiswari Rankappagounder Natarajan Signed-off-by: Kun Yi Signed-off-by: Benjamin Fair --- drivers/misc/Kconfig | 8 ++ drivers/misc/Makefile | 1 + drivers/misc/seven_seg_disp.c | 201 ++++++++++++++++++++++++++++++++++ drivers/misc/seven_seg_disp.h | 34 ++++++ 4 files changed, 244 insertions(+) create mode 100644 drivers/misc/seven_seg_disp.c create mode 100644 drivers/misc/seven_seg_disp.h diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig index 9d96469fb41c..d443de886346 100644 --- a/drivers/misc/Kconfig +++ b/drivers/misc/Kconfig @@ -473,6 +473,14 @@ config VEXPRESS_SYSCFG bus. System Configuration interface is one of the possible means of generating transactions on this bus. +config SEVEN_SEGMENT_DISPLAY + tristate "Character driver for seven segment display support" + help + Character device driver which implements the user-space + API for letting a user write to two 7-segment displays including + any conversion methods necessary to map the user input + to two 7-segment displays. + config PCI_ENDPOINT_TEST depends on PCI select CRC32 diff --git a/drivers/misc/seven_seg_disp.c b/drivers/misc/seven_seg_disp.c new file mode 100644 index 000000000000..db1c571f68e5 --- /dev/null +++ b/drivers/misc/seven_seg_disp.c @@ -0,0 +1,201 @@ +/* + * Copyright (c) 2016 Google, Inc + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 or later as + * published by the Free Software Foundation. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "seven_seg_disp.h" + +#define LED_DOT 0x01 + +/* + * 0 1 2 3 4 5 6 7 8 9 A B C D E F + * _ _ _ _ _ _ _ _ _ _ _ _ + * | | | _| _| |_| |_ |_ | |_| |_| |_| |_ | _| |_ |_ + * |_| | |_ _| | _| |_| | |_| | | | |_| |_ |_| |_ | + * + * data[7:1] = led[a:g] + */ +const u8 seven_seg_bits[] = { + 0xFC, 0x60, 0xDA, 0xF2, 0x66, 0xB6, 0xBE, 0xE0, + 0xFE, 0xF6, 0xEE, 0x3E, 0x9C, 0x7A, 0x9E, 0x8E + }; + +/* + * 0 1 2 3 4 5 6 7 8 9 A B C D E F + * _ _ _ _ _ + * | |_ |_| |_ _ _ _ _ _ _ _ |_ _| _| | | + * |_ |_ | | _| |_| |_| | | + * + * data[7:1] = led[a:g] + */ +const u8 special_seven_seg_bits[] = { + 0x00, 0x9C, 0x1E, 0xCE, 0x8E, 0x02, 0x02, 0x02, + 0x02, 0x02, 0x02, 0x02, 0xB6, 0x7A, 0x7A, 0xEC + }; + +static dev_t seven_seg_devno; +static struct class *seven_seg_disp_class; + +static int seven_seg_disp_open(struct inode *inode, struct file *filp) +{ + struct seven_seg_disp_dev *disp_dev; + + disp_dev = container_of(inode->i_cdev, + struct seven_seg_disp_dev, cdev); + filp->private_data = disp_dev; + return 0; +} + +static int seven_seg_disp_close(struct inode *inode, struct file *filp) +{ + filp->private_data = NULL; + return 0; +} + +static ssize_t seven_seg_disp_read(struct file *filp, char __user *buf, size_t + len, loff_t *off) +{ + struct seven_seg_disp_dev *disp_dev = filp->private_data; + + if (disp_dev->disp_data_valid) + return -EINVAL; + + if (copy_to_user(buf, disp_dev->seven_seg_disp_data_array, + MAX_DISP_CHAR_SIZE) != 0) { + return -EFAULT; + } + + return 0; +} + +static u16 convert_to_disp_data(char *buf) +{ + u8 low_display; + u8 high_display; + u16 led_value; + + low_display = seven_seg_bits[hex_to_bin(buf[2])]; + + high_display = (buf[0] == '1') ? + special_seven_seg_bits[hex_to_bin(buf[1])] : + seven_seg_bits[hex_to_bin(buf[1])]; + + led_value = low_display | (high_display << 8); + if (buf[0] == '1') + led_value |= LED_DOT | (LED_DOT << 8); + + return led_value; +} + +static ssize_t seven_seg_disp_write(struct file *filp, const char __user *buf, + size_t len, loff_t *off) +{ + int length = len - 1; + int i; + + struct seven_seg_disp_dev *disp_dev = filp->private_data; + + if (length != MAX_DISP_CHAR_SIZE) + return -EINVAL; + + if (copy_from_user(disp_dev->seven_seg_disp_data_array, + buf, length) != 0) { + return -EFAULT; + } + + for (i = 0; i < MAX_DISP_CHAR_SIZE; i++) { + if (!isxdigit(disp_dev->seven_seg_disp_data_array[i])) + return -EINVAL; + } + + disp_dev->current_seven_seg_disp_data = convert_to_disp_data( + disp_dev->seven_seg_disp_data_array); + disp_dev->disp_data_valid = true; + disp_dev->update_seven_seg_data(&disp_dev->parent, + disp_dev->current_seven_seg_disp_data); + + return len; +} + +static const struct file_operations seven_seg_disp_fops = { + + .owner = THIS_MODULE, + .open = seven_seg_disp_open, + .release = seven_seg_disp_close, + .read = seven_seg_disp_read, + .write = seven_seg_disp_write +}; + +void seven_seg_rem_cdev(struct seven_seg_disp_dev *disp_dev) +{ + cdev_del(&disp_dev->cdev); + device_destroy(seven_seg_disp_class, seven_seg_devno); +} + +int seven_seg_setup_cdev(struct seven_seg_disp_dev *disp_dev, + void (*update_disp_data)(struct device *, u16 data)) +{ + struct device *dev; + int err; + + dev = device_create(seven_seg_disp_class, NULL, + seven_seg_devno, + NULL, "seven_seg_disp_val"); + if (dev == NULL) + return -EIO; + disp_dev->dev = dev; + disp_dev->update_seven_seg_data = update_disp_data; + disp_dev->disp_data_valid = false; + + cdev_init(&disp_dev->cdev, &seven_seg_disp_fops); + err = cdev_add(&disp_dev->cdev, seven_seg_devno, 1); + if (err) + device_destroy(seven_seg_disp_class, seven_seg_devno); + return err; +} + +static int __init seven_seg_disp_init(void) +{ + int err = alloc_chrdev_region(&seven_seg_devno, 0, 1, "disp_state"); + + if (err < 0) + return err; + + seven_seg_disp_class = class_create(THIS_MODULE, "disp_state"); + if (seven_seg_disp_class == NULL) + goto unreg_chrdev; + + return 0; + +unreg_chrdev: + unregister_chrdev_region(seven_seg_devno, 1); + return -EIO; +} + +static void __exit seven_seg_disp_exit(void) +{ + class_destroy(seven_seg_disp_class); + unregister_chrdev_region(seven_seg_devno, 1); +} + +module_init(seven_seg_disp_init); +module_exit(seven_seg_disp_exit); +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Jaghathiswari Rankappagounder Natarajan "); +MODULE_DESCRIPTION("Seven segment display character driver"); diff --git a/drivers/misc/seven_seg_disp.h b/drivers/misc/seven_seg_disp.h new file mode 100644 index 000000000000..0ebed0802747 --- /dev/null +++ b/drivers/misc/seven_seg_disp.h @@ -0,0 +1,34 @@ +/* + * Copyright (c) 2016 Google, Inc + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 or later as + * published by the Free Software Foundation. + */ + +#ifndef SEVEN_SEG_DISP_H +#define SEVEN_SEG_DISP_H + +#include +#include + +#define MAX_DISP_CHAR_SIZE 3 + +#define DEFAULT_REFRESH_INTERVAL_MS 600 + +struct seven_seg_disp_dev { + bool disp_data_valid; + u16 current_seven_seg_disp_data; + char seven_seg_disp_data_array[MAX_DISP_CHAR_SIZE]; + struct device parent; + struct device *dev; + struct cdev cdev; + void (*update_seven_seg_data)(struct device *, u16 data); +}; + +int seven_seg_setup_cdev(struct seven_seg_disp_dev *disp_dev, + void (*update_disp_data)(struct device *, u16 data)); + +void seven_seg_rem_cdev(struct seven_seg_disp_dev *disp_dev); + +#endif -- 2.22.0.770.g0f2c4a37fd-goog