H Hartley Sweeten | 76abbdde | 2013-06-11 10:38:59 -0700 | [diff] [blame] | 1 | /* |
| 2 | * A simple sysfs interface for the generic PWM framework |
| 3 | * |
| 4 | * Copyright (C) 2013 H Hartley Sweeten <hsweeten@visionengravers.com> |
| 5 | * |
| 6 | * Based on previous work by Lars Poeschel <poeschel@lemonage.de> |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License as published by |
| 10 | * the Free Software Foundation; either version 2, or (at your option) |
| 11 | * any later version. |
| 12 | * |
| 13 | * This program is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | * GNU General Public License for more details. |
| 17 | */ |
| 18 | |
| 19 | #include <linux/device.h> |
| 20 | #include <linux/mutex.h> |
| 21 | #include <linux/err.h> |
| 22 | #include <linux/slab.h> |
| 23 | #include <linux/kdev_t.h> |
| 24 | #include <linux/pwm.h> |
| 25 | |
| 26 | struct pwm_export { |
| 27 | struct device child; |
| 28 | struct pwm_device *pwm; |
| 29 | }; |
| 30 | |
| 31 | static struct pwm_export *child_to_pwm_export(struct device *child) |
| 32 | { |
| 33 | return container_of(child, struct pwm_export, child); |
| 34 | } |
| 35 | |
| 36 | static struct pwm_device *child_to_pwm_device(struct device *child) |
| 37 | { |
| 38 | struct pwm_export *export = child_to_pwm_export(child); |
| 39 | |
| 40 | return export->pwm; |
| 41 | } |
| 42 | |
| 43 | static ssize_t pwm_period_show(struct device *child, |
| 44 | struct device_attribute *attr, |
| 45 | char *buf) |
| 46 | { |
| 47 | const struct pwm_device *pwm = child_to_pwm_device(child); |
| 48 | |
| 49 | return sprintf(buf, "%u\n", pwm->period); |
| 50 | } |
| 51 | |
| 52 | static ssize_t pwm_period_store(struct device *child, |
| 53 | struct device_attribute *attr, |
| 54 | const char *buf, size_t size) |
| 55 | { |
| 56 | struct pwm_device *pwm = child_to_pwm_device(child); |
| 57 | unsigned int val; |
| 58 | int ret; |
| 59 | |
| 60 | ret = kstrtouint(buf, 0, &val); |
| 61 | if (ret) |
| 62 | return ret; |
| 63 | |
| 64 | ret = pwm_config(pwm, pwm->duty_cycle, val); |
| 65 | |
| 66 | return ret ? : size; |
| 67 | } |
| 68 | |
| 69 | static ssize_t pwm_duty_cycle_show(struct device *child, |
| 70 | struct device_attribute *attr, |
| 71 | char *buf) |
| 72 | { |
| 73 | const struct pwm_device *pwm = child_to_pwm_device(child); |
| 74 | |
| 75 | return sprintf(buf, "%u\n", pwm->duty_cycle); |
| 76 | } |
| 77 | |
| 78 | static ssize_t pwm_duty_cycle_store(struct device *child, |
| 79 | struct device_attribute *attr, |
| 80 | const char *buf, size_t size) |
| 81 | { |
| 82 | struct pwm_device *pwm = child_to_pwm_device(child); |
| 83 | unsigned int val; |
| 84 | int ret; |
| 85 | |
| 86 | ret = kstrtouint(buf, 0, &val); |
| 87 | if (ret) |
| 88 | return ret; |
| 89 | |
| 90 | ret = pwm_config(pwm, val, pwm->period); |
| 91 | |
| 92 | return ret ? : size; |
| 93 | } |
| 94 | |
| 95 | static ssize_t pwm_enable_show(struct device *child, |
| 96 | struct device_attribute *attr, |
| 97 | char *buf) |
| 98 | { |
| 99 | const struct pwm_device *pwm = child_to_pwm_device(child); |
| 100 | int enabled = test_bit(PWMF_ENABLED, &pwm->flags); |
| 101 | |
| 102 | return sprintf(buf, "%d\n", enabled); |
| 103 | } |
| 104 | |
| 105 | static ssize_t pwm_enable_store(struct device *child, |
| 106 | struct device_attribute *attr, |
| 107 | const char *buf, size_t size) |
| 108 | { |
| 109 | struct pwm_device *pwm = child_to_pwm_device(child); |
| 110 | int val, ret; |
| 111 | |
| 112 | ret = kstrtoint(buf, 0, &val); |
| 113 | if (ret) |
| 114 | return ret; |
| 115 | |
| 116 | switch (val) { |
| 117 | case 0: |
| 118 | pwm_disable(pwm); |
| 119 | break; |
| 120 | case 1: |
| 121 | ret = pwm_enable(pwm); |
| 122 | break; |
| 123 | default: |
| 124 | ret = -EINVAL; |
| 125 | break; |
| 126 | } |
| 127 | |
| 128 | return ret ? : size; |
| 129 | } |
| 130 | |
| 131 | static ssize_t pwm_polarity_show(struct device *child, |
| 132 | struct device_attribute *attr, |
| 133 | char *buf) |
| 134 | { |
| 135 | const struct pwm_device *pwm = child_to_pwm_device(child); |
| 136 | |
| 137 | return sprintf(buf, "%s\n", pwm->polarity ? "inversed" : "normal"); |
| 138 | } |
| 139 | |
| 140 | static ssize_t pwm_polarity_store(struct device *child, |
| 141 | struct device_attribute *attr, |
| 142 | const char *buf, size_t size) |
| 143 | { |
| 144 | struct pwm_device *pwm = child_to_pwm_device(child); |
| 145 | enum pwm_polarity polarity; |
| 146 | int ret; |
| 147 | |
| 148 | if (sysfs_streq(buf, "normal")) |
| 149 | polarity = PWM_POLARITY_NORMAL; |
| 150 | else if (sysfs_streq(buf, "inversed")) |
| 151 | polarity = PWM_POLARITY_INVERSED; |
| 152 | else |
| 153 | return -EINVAL; |
| 154 | |
| 155 | ret = pwm_set_polarity(pwm, polarity); |
| 156 | |
| 157 | return ret ? : size; |
| 158 | } |
| 159 | |
| 160 | static DEVICE_ATTR(period, 0644, pwm_period_show, pwm_period_store); |
| 161 | static DEVICE_ATTR(duty_cycle, 0644, pwm_duty_cycle_show, pwm_duty_cycle_store); |
| 162 | static DEVICE_ATTR(enable, 0644, pwm_enable_show, pwm_enable_store); |
| 163 | static DEVICE_ATTR(polarity, 0644, pwm_polarity_show, pwm_polarity_store); |
| 164 | |
| 165 | static struct attribute *pwm_attrs[] = { |
| 166 | &dev_attr_period.attr, |
| 167 | &dev_attr_duty_cycle.attr, |
| 168 | &dev_attr_enable.attr, |
| 169 | &dev_attr_polarity.attr, |
| 170 | NULL |
| 171 | }; |
| 172 | |
| 173 | static const struct attribute_group pwm_attr_group = { |
| 174 | .attrs = pwm_attrs, |
| 175 | }; |
| 176 | |
| 177 | static const struct attribute_group *pwm_attr_groups[] = { |
| 178 | &pwm_attr_group, |
| 179 | NULL, |
| 180 | }; |
| 181 | |
| 182 | static void pwm_export_release(struct device *child) |
| 183 | { |
| 184 | struct pwm_export *export = child_to_pwm_export(child); |
| 185 | |
| 186 | kfree(export); |
| 187 | } |
| 188 | |
| 189 | static int pwm_export_child(struct device *parent, struct pwm_device *pwm) |
| 190 | { |
| 191 | struct pwm_export *export; |
| 192 | int ret; |
| 193 | |
| 194 | if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags)) |
| 195 | return -EBUSY; |
| 196 | |
| 197 | export = kzalloc(sizeof(*export), GFP_KERNEL); |
| 198 | if (!export) { |
| 199 | clear_bit(PWMF_EXPORTED, &pwm->flags); |
| 200 | return -ENOMEM; |
| 201 | } |
| 202 | |
| 203 | export->pwm = pwm; |
| 204 | |
| 205 | export->child.release = pwm_export_release; |
| 206 | export->child.parent = parent; |
| 207 | export->child.devt = MKDEV(0, 0); |
| 208 | export->child.groups = pwm_attr_groups; |
| 209 | dev_set_name(&export->child, "pwm%u", pwm->hwpwm); |
| 210 | |
| 211 | ret = device_register(&export->child); |
| 212 | if (ret) { |
| 213 | clear_bit(PWMF_EXPORTED, &pwm->flags); |
| 214 | kfree(export); |
| 215 | return ret; |
| 216 | } |
| 217 | |
| 218 | return 0; |
| 219 | } |
| 220 | |
| 221 | static int pwm_unexport_match(struct device *child, void *data) |
| 222 | { |
| 223 | return child_to_pwm_device(child) == data; |
| 224 | } |
| 225 | |
| 226 | static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm) |
| 227 | { |
| 228 | struct device *child; |
| 229 | |
| 230 | if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags)) |
| 231 | return -ENODEV; |
| 232 | |
| 233 | child = device_find_child(parent, pwm, pwm_unexport_match); |
| 234 | if (!child) |
| 235 | return -ENODEV; |
| 236 | |
| 237 | /* for device_find_child() */ |
| 238 | put_device(child); |
| 239 | device_unregister(child); |
| 240 | pwm_put(pwm); |
| 241 | |
| 242 | return 0; |
| 243 | } |
| 244 | |
| 245 | static ssize_t pwm_export_store(struct device *parent, |
| 246 | struct device_attribute *attr, |
| 247 | const char *buf, size_t len) |
| 248 | { |
| 249 | struct pwm_chip *chip = dev_get_drvdata(parent); |
| 250 | struct pwm_device *pwm; |
| 251 | unsigned int hwpwm; |
| 252 | int ret; |
| 253 | |
| 254 | ret = kstrtouint(buf, 0, &hwpwm); |
| 255 | if (ret < 0) |
| 256 | return ret; |
| 257 | |
| 258 | if (hwpwm >= chip->npwm) |
| 259 | return -ENODEV; |
| 260 | |
| 261 | pwm = pwm_request_from_chip(chip, hwpwm, "sysfs"); |
| 262 | if (IS_ERR(pwm)) |
| 263 | return PTR_ERR(pwm); |
| 264 | |
| 265 | ret = pwm_export_child(parent, pwm); |
| 266 | if (ret < 0) |
| 267 | pwm_put(pwm); |
| 268 | |
| 269 | return ret ? : len; |
| 270 | } |
| 271 | |
| 272 | static ssize_t pwm_unexport_store(struct device *parent, |
| 273 | struct device_attribute *attr, |
| 274 | const char *buf, size_t len) |
| 275 | { |
| 276 | struct pwm_chip *chip = dev_get_drvdata(parent); |
| 277 | unsigned int hwpwm; |
| 278 | int ret; |
| 279 | |
| 280 | ret = kstrtouint(buf, 0, &hwpwm); |
| 281 | if (ret < 0) |
| 282 | return ret; |
| 283 | |
| 284 | if (hwpwm >= chip->npwm) |
| 285 | return -ENODEV; |
| 286 | |
| 287 | ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]); |
| 288 | |
| 289 | return ret ? : len; |
| 290 | } |
| 291 | |
| 292 | static ssize_t pwm_npwm_show(struct device *parent, |
| 293 | struct device_attribute *attr, |
| 294 | char *buf) |
| 295 | { |
| 296 | const struct pwm_chip *chip = dev_get_drvdata(parent); |
| 297 | |
| 298 | return sprintf(buf, "%u\n", chip->npwm); |
| 299 | } |
| 300 | |
| 301 | static struct device_attribute pwm_chip_attrs[] = { |
| 302 | __ATTR(export, 0200, NULL, pwm_export_store), |
| 303 | __ATTR(unexport, 0200, NULL, pwm_unexport_store), |
| 304 | __ATTR(npwm, 0444, pwm_npwm_show, NULL), |
| 305 | __ATTR_NULL, |
| 306 | }; |
| 307 | |
| 308 | static struct class pwm_class = { |
| 309 | .name = "pwm", |
| 310 | .owner = THIS_MODULE, |
| 311 | .dev_attrs = pwm_chip_attrs, |
| 312 | }; |
| 313 | |
| 314 | static int pwmchip_sysfs_match(struct device *parent, const void *data) |
| 315 | { |
| 316 | return dev_get_drvdata(parent) == data; |
| 317 | } |
| 318 | |
| 319 | void pwmchip_sysfs_export(struct pwm_chip *chip) |
| 320 | { |
| 321 | struct device *parent; |
| 322 | |
| 323 | /* |
| 324 | * If device_create() fails the pwm_chip is still usable by |
| 325 | * the kernel its just not exported. |
| 326 | */ |
| 327 | parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip, |
| 328 | "pwmchip%d", chip->base); |
| 329 | if (IS_ERR(parent)) { |
| 330 | dev_warn(chip->dev, |
| 331 | "device_create failed for pwm_chip sysfs export\n"); |
| 332 | } |
| 333 | } |
| 334 | |
| 335 | void pwmchip_sysfs_unexport(struct pwm_chip *chip) |
| 336 | { |
| 337 | struct device *parent; |
| 338 | |
| 339 | parent = class_find_device(&pwm_class, NULL, chip, |
| 340 | pwmchip_sysfs_match); |
| 341 | if (parent) { |
| 342 | /* for class_find_device() */ |
| 343 | put_device(parent); |
| 344 | device_unregister(parent); |
| 345 | } |
| 346 | } |
| 347 | |
| 348 | static int __init pwm_sysfs_init(void) |
| 349 | { |
| 350 | return class_register(&pwm_class); |
| 351 | } |
| 352 | subsys_initcall(pwm_sysfs_init); |