George Hung | d9f9d7e | 2020-07-16 22:03:39 +0800 | [diff] [blame^] | 1 | From 2d46e81d9bbb624695bac8400a4ac41b7f116ec4 Mon Sep 17 00:00:00 2001 |
| 2 | From: Jaghathiswari Rankappagounder Natarajan <jaghu@google.com> |
| 3 | Date: Fri, 27 Jul 2018 12:34:54 -0700 |
| 4 | Subject: [PATCH 2/3] drivers: misc: Character device driver for seven segment |
| 5 | display |
| 6 | |
| 7 | Character device driver which implements the user-space |
| 8 | API for letting a user write to two 7-segment displays including |
| 9 | any conversion methods necessary to map the user input |
| 10 | to two 7-segment displays. |
| 11 | |
| 12 | Signed-off-by: Jaghathiswari Rankappagounder Natarajan <jaghu@google.com> |
| 13 | Signed-off-by: Kun Yi <kunyi@google.com> |
| 14 | Signed-off-by: Benjamin Fair <benjaminfair@google.com> |
| 15 | --- |
| 16 | drivers/misc/Kconfig | 8 ++ |
| 17 | drivers/misc/Makefile | 1 + |
| 18 | drivers/misc/seven_seg_disp.c | 201 ++++++++++++++++++++++++++++++++++ |
| 19 | drivers/misc/seven_seg_disp.h | 34 ++++++ |
| 20 | 4 files changed, 244 insertions(+) |
| 21 | create mode 100644 drivers/misc/seven_seg_disp.c |
| 22 | create mode 100644 drivers/misc/seven_seg_disp.h |
| 23 | |
| 24 | diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig |
| 25 | index 9d96469fb41c..d443de886346 100644 |
| 26 | --- a/drivers/misc/Kconfig |
| 27 | +++ b/drivers/misc/Kconfig |
| 28 | @@ -473,6 +473,14 @@ config VEXPRESS_SYSCFG |
| 29 | bus. System Configuration interface is one of the possible means |
| 30 | of generating transactions on this bus. |
| 31 | |
| 32 | +config SEVEN_SEGMENT_DISPLAY |
| 33 | + tristate "Character driver for seven segment display support" |
| 34 | + help |
| 35 | + Character device driver which implements the user-space |
| 36 | + API for letting a user write to two 7-segment displays including |
| 37 | + any conversion methods necessary to map the user input |
| 38 | + to two 7-segment displays. |
| 39 | + |
| 40 | config PCI_ENDPOINT_TEST |
| 41 | depends on PCI |
| 42 | select CRC32 |
| 43 | |
| 44 | diff --git a/drivers/misc/seven_seg_disp.c b/drivers/misc/seven_seg_disp.c |
| 45 | new file mode 100644 |
| 46 | index 000000000000..db1c571f68e5 |
| 47 | --- /dev/null |
| 48 | +++ b/drivers/misc/seven_seg_disp.c |
| 49 | @@ -0,0 +1,201 @@ |
| 50 | +/* |
| 51 | + * Copyright (c) 2016 Google, Inc |
| 52 | + * |
| 53 | + * This program is free software; you can redistribute it and/or modify |
| 54 | + * it under the terms of the GNU General Public License version 2 or later as |
| 55 | + * published by the Free Software Foundation. |
| 56 | + */ |
| 57 | + |
| 58 | +#include <linux/module.h> |
| 59 | +#include <linux/version.h> |
| 60 | +#include <linux/kernel.h> |
| 61 | +#include <linux/types.h> |
| 62 | +#include <linux/kdev_t.h> |
| 63 | +#include <linux/fs.h> |
| 64 | +#include <linux/uaccess.h> |
| 65 | +#include <linux/ctype.h> |
| 66 | +#include <linux/of.h> |
| 67 | +#include <linux/io.h> |
| 68 | +#include <linux/slab.h> |
| 69 | +#include <linux/platform_device.h> |
| 70 | + |
| 71 | +#include "seven_seg_disp.h" |
| 72 | + |
| 73 | +#define LED_DOT 0x01 |
| 74 | + |
| 75 | +/* |
| 76 | + * 0 1 2 3 4 5 6 7 8 9 A B C D E F |
| 77 | + * _ _ _ _ _ _ _ _ _ _ _ _ |
| 78 | + * | | | _| _| |_| |_ |_ | |_| |_| |_| |_ | _| |_ |_ |
| 79 | + * |_| | |_ _| | _| |_| | |_| | | | |_| |_ |_| |_ | |
| 80 | + * |
| 81 | + * data[7:1] = led[a:g] |
| 82 | + */ |
| 83 | +const u8 seven_seg_bits[] = { |
| 84 | + 0xFC, 0x60, 0xDA, 0xF2, 0x66, 0xB6, 0xBE, 0xE0, |
| 85 | + 0xFE, 0xF6, 0xEE, 0x3E, 0x9C, 0x7A, 0x9E, 0x8E |
| 86 | + }; |
| 87 | + |
| 88 | +/* |
| 89 | + * 0 1 2 3 4 5 6 7 8 9 A B C D E F |
| 90 | + * _ _ _ _ _ |
| 91 | + * | |_ |_| |_ _ _ _ _ _ _ _ |_ _| _| | | |
| 92 | + * |_ |_ | | _| |_| |_| | | |
| 93 | + * |
| 94 | + * data[7:1] = led[a:g] |
| 95 | + */ |
| 96 | +const u8 special_seven_seg_bits[] = { |
| 97 | + 0x00, 0x9C, 0x1E, 0xCE, 0x8E, 0x02, 0x02, 0x02, |
| 98 | + 0x02, 0x02, 0x02, 0x02, 0xB6, 0x7A, 0x7A, 0xEC |
| 99 | + }; |
| 100 | + |
| 101 | +static dev_t seven_seg_devno; |
| 102 | +static struct class *seven_seg_disp_class; |
| 103 | + |
| 104 | +static int seven_seg_disp_open(struct inode *inode, struct file *filp) |
| 105 | +{ |
| 106 | + struct seven_seg_disp_dev *disp_dev; |
| 107 | + |
| 108 | + disp_dev = container_of(inode->i_cdev, |
| 109 | + struct seven_seg_disp_dev, cdev); |
| 110 | + filp->private_data = disp_dev; |
| 111 | + return 0; |
| 112 | +} |
| 113 | + |
| 114 | +static int seven_seg_disp_close(struct inode *inode, struct file *filp) |
| 115 | +{ |
| 116 | + filp->private_data = NULL; |
| 117 | + return 0; |
| 118 | +} |
| 119 | + |
| 120 | +static ssize_t seven_seg_disp_read(struct file *filp, char __user *buf, size_t |
| 121 | + len, loff_t *off) |
| 122 | +{ |
| 123 | + struct seven_seg_disp_dev *disp_dev = filp->private_data; |
| 124 | + |
| 125 | + if (disp_dev->disp_data_valid) |
| 126 | + return -EINVAL; |
| 127 | + |
| 128 | + if (copy_to_user(buf, disp_dev->seven_seg_disp_data_array, |
| 129 | + MAX_DISP_CHAR_SIZE) != 0) { |
| 130 | + return -EFAULT; |
| 131 | + } |
| 132 | + |
| 133 | + return 0; |
| 134 | +} |
| 135 | + |
| 136 | +static u16 convert_to_disp_data(char *buf) |
| 137 | +{ |
| 138 | + u8 low_display; |
| 139 | + u8 high_display; |
| 140 | + u16 led_value; |
| 141 | + |
| 142 | + low_display = seven_seg_bits[hex_to_bin(buf[2])]; |
| 143 | + |
| 144 | + high_display = (buf[0] == '1') ? |
| 145 | + special_seven_seg_bits[hex_to_bin(buf[1])] : |
| 146 | + seven_seg_bits[hex_to_bin(buf[1])]; |
| 147 | + |
| 148 | + led_value = low_display | (high_display << 8); |
| 149 | + if (buf[0] == '1') |
| 150 | + led_value |= LED_DOT | (LED_DOT << 8); |
| 151 | + |
| 152 | + return led_value; |
| 153 | +} |
| 154 | + |
| 155 | +static ssize_t seven_seg_disp_write(struct file *filp, const char __user *buf, |
| 156 | + size_t len, loff_t *off) |
| 157 | +{ |
| 158 | + int length = len - 1; |
| 159 | + int i; |
| 160 | + |
| 161 | + struct seven_seg_disp_dev *disp_dev = filp->private_data; |
| 162 | + |
| 163 | + if (length != MAX_DISP_CHAR_SIZE) |
| 164 | + return -EINVAL; |
| 165 | + |
| 166 | + if (copy_from_user(disp_dev->seven_seg_disp_data_array, |
| 167 | + buf, length) != 0) { |
| 168 | + return -EFAULT; |
| 169 | + } |
| 170 | + |
| 171 | + for (i = 0; i < MAX_DISP_CHAR_SIZE; i++) { |
| 172 | + if (!isxdigit(disp_dev->seven_seg_disp_data_array[i])) |
| 173 | + return -EINVAL; |
| 174 | + } |
| 175 | + |
| 176 | + disp_dev->current_seven_seg_disp_data = convert_to_disp_data( |
| 177 | + disp_dev->seven_seg_disp_data_array); |
| 178 | + disp_dev->disp_data_valid = true; |
| 179 | + disp_dev->update_seven_seg_data(&disp_dev->parent, |
| 180 | + disp_dev->current_seven_seg_disp_data); |
| 181 | + |
| 182 | + return len; |
| 183 | +} |
| 184 | + |
| 185 | +static const struct file_operations seven_seg_disp_fops = { |
| 186 | + |
| 187 | + .owner = THIS_MODULE, |
| 188 | + .open = seven_seg_disp_open, |
| 189 | + .release = seven_seg_disp_close, |
| 190 | + .read = seven_seg_disp_read, |
| 191 | + .write = seven_seg_disp_write |
| 192 | +}; |
| 193 | + |
| 194 | +void seven_seg_rem_cdev(struct seven_seg_disp_dev *disp_dev) |
| 195 | +{ |
| 196 | + cdev_del(&disp_dev->cdev); |
| 197 | + device_destroy(seven_seg_disp_class, seven_seg_devno); |
| 198 | +} |
| 199 | + |
| 200 | +int seven_seg_setup_cdev(struct seven_seg_disp_dev *disp_dev, |
| 201 | + void (*update_disp_data)(struct device *, u16 data)) |
| 202 | +{ |
| 203 | + struct device *dev; |
| 204 | + int err; |
| 205 | + |
| 206 | + dev = device_create(seven_seg_disp_class, NULL, |
| 207 | + seven_seg_devno, |
| 208 | + NULL, "seven_seg_disp_val"); |
| 209 | + if (dev == NULL) |
| 210 | + return -EIO; |
| 211 | + disp_dev->dev = dev; |
| 212 | + disp_dev->update_seven_seg_data = update_disp_data; |
| 213 | + disp_dev->disp_data_valid = false; |
| 214 | + |
| 215 | + cdev_init(&disp_dev->cdev, &seven_seg_disp_fops); |
| 216 | + err = cdev_add(&disp_dev->cdev, seven_seg_devno, 1); |
| 217 | + if (err) |
| 218 | + device_destroy(seven_seg_disp_class, seven_seg_devno); |
| 219 | + return err; |
| 220 | +} |
| 221 | + |
| 222 | +static int __init seven_seg_disp_init(void) |
| 223 | +{ |
| 224 | + int err = alloc_chrdev_region(&seven_seg_devno, 0, 1, "disp_state"); |
| 225 | + |
| 226 | + if (err < 0) |
| 227 | + return err; |
| 228 | + |
| 229 | + seven_seg_disp_class = class_create(THIS_MODULE, "disp_state"); |
| 230 | + if (seven_seg_disp_class == NULL) |
| 231 | + goto unreg_chrdev; |
| 232 | + |
| 233 | + return 0; |
| 234 | + |
| 235 | +unreg_chrdev: |
| 236 | + unregister_chrdev_region(seven_seg_devno, 1); |
| 237 | + return -EIO; |
| 238 | +} |
| 239 | + |
| 240 | +static void __exit seven_seg_disp_exit(void) |
| 241 | +{ |
| 242 | + class_destroy(seven_seg_disp_class); |
| 243 | + unregister_chrdev_region(seven_seg_devno, 1); |
| 244 | +} |
| 245 | + |
| 246 | +module_init(seven_seg_disp_init); |
| 247 | +module_exit(seven_seg_disp_exit); |
| 248 | +MODULE_LICENSE("GPL"); |
| 249 | +MODULE_AUTHOR("Jaghathiswari Rankappagounder Natarajan <jaghu@google.com>"); |
| 250 | +MODULE_DESCRIPTION("Seven segment display character driver"); |
| 251 | diff --git a/drivers/misc/seven_seg_disp.h b/drivers/misc/seven_seg_disp.h |
| 252 | new file mode 100644 |
| 253 | index 000000000000..0ebed0802747 |
| 254 | --- /dev/null |
| 255 | +++ b/drivers/misc/seven_seg_disp.h |
| 256 | @@ -0,0 +1,34 @@ |
| 257 | +/* |
| 258 | + * Copyright (c) 2016 Google, Inc |
| 259 | + * |
| 260 | + * This program is free software; you can redistribute it and/or modify |
| 261 | + * it under the terms of the GNU General Public License version 2 or later as |
| 262 | + * published by the Free Software Foundation. |
| 263 | + */ |
| 264 | + |
| 265 | +#ifndef SEVEN_SEG_DISP_H |
| 266 | +#define SEVEN_SEG_DISP_H |
| 267 | + |
| 268 | +#include <linux/device.h> |
| 269 | +#include <linux/cdev.h> |
| 270 | + |
| 271 | +#define MAX_DISP_CHAR_SIZE 3 |
| 272 | + |
| 273 | +#define DEFAULT_REFRESH_INTERVAL_MS 600 |
| 274 | + |
| 275 | +struct seven_seg_disp_dev { |
| 276 | + bool disp_data_valid; |
| 277 | + u16 current_seven_seg_disp_data; |
| 278 | + char seven_seg_disp_data_array[MAX_DISP_CHAR_SIZE]; |
| 279 | + struct device parent; |
| 280 | + struct device *dev; |
| 281 | + struct cdev cdev; |
| 282 | + void (*update_seven_seg_data)(struct device *, u16 data); |
| 283 | +}; |
| 284 | + |
| 285 | +int seven_seg_setup_cdev(struct seven_seg_disp_dev *disp_dev, |
| 286 | + void (*update_disp_data)(struct device *, u16 data)); |
| 287 | + |
| 288 | +void seven_seg_rem_cdev(struct seven_seg_disp_dev *disp_dev); |
| 289 | + |
| 290 | +#endif |
| 291 | -- |
| 292 | 2.22.0.770.g0f2c4a37fd-goog |
| 293 | |