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); 353