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 ATTRIBUTE_GROUPS(pwm); 173 174 static void pwm_export_release(struct device *child) 175 { 176 struct pwm_export *export = child_to_pwm_export(child); 177 178 kfree(export); 179 } 180 181 static int pwm_export_child(struct device *parent, struct pwm_device *pwm) 182 { 183 struct pwm_export *export; 184 int ret; 185 186 if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags)) 187 return -EBUSY; 188 189 export = kzalloc(sizeof(*export), GFP_KERNEL); 190 if (!export) { 191 clear_bit(PWMF_EXPORTED, &pwm->flags); 192 return -ENOMEM; 193 } 194 195 export->pwm = pwm; 196 197 export->child.release = pwm_export_release; 198 export->child.parent = parent; 199 export->child.devt = MKDEV(0, 0); 200 export->child.groups = pwm_groups; 201 dev_set_name(&export->child, "pwm%u", pwm->hwpwm); 202 203 ret = device_register(&export->child); 204 if (ret) { 205 clear_bit(PWMF_EXPORTED, &pwm->flags); 206 kfree(export); 207 return ret; 208 } 209 210 return 0; 211 } 212 213 static int pwm_unexport_match(struct device *child, void *data) 214 { 215 return child_to_pwm_device(child) == data; 216 } 217 218 static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm) 219 { 220 struct device *child; 221 222 if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags)) 223 return -ENODEV; 224 225 child = device_find_child(parent, pwm, pwm_unexport_match); 226 if (!child) 227 return -ENODEV; 228 229 /* for device_find_child() */ 230 put_device(child); 231 device_unregister(child); 232 pwm_put(pwm); 233 234 return 0; 235 } 236 237 static ssize_t pwm_export_store(struct device *parent, 238 struct device_attribute *attr, 239 const char *buf, size_t len) 240 { 241 struct pwm_chip *chip = dev_get_drvdata(parent); 242 struct pwm_device *pwm; 243 unsigned int hwpwm; 244 int ret; 245 246 ret = kstrtouint(buf, 0, &hwpwm); 247 if (ret < 0) 248 return ret; 249 250 if (hwpwm >= chip->npwm) 251 return -ENODEV; 252 253 pwm = pwm_request_from_chip(chip, hwpwm, "sysfs"); 254 if (IS_ERR(pwm)) 255 return PTR_ERR(pwm); 256 257 ret = pwm_export_child(parent, pwm); 258 if (ret < 0) 259 pwm_put(pwm); 260 261 return ret ? : len; 262 } 263 static DEVICE_ATTR(export, 0200, NULL, pwm_export_store); 264 265 static ssize_t pwm_unexport_store(struct device *parent, 266 struct device_attribute *attr, 267 const char *buf, size_t len) 268 { 269 struct pwm_chip *chip = dev_get_drvdata(parent); 270 unsigned int hwpwm; 271 int ret; 272 273 ret = kstrtouint(buf, 0, &hwpwm); 274 if (ret < 0) 275 return ret; 276 277 if (hwpwm >= chip->npwm) 278 return -ENODEV; 279 280 ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]); 281 282 return ret ? : len; 283 } 284 static DEVICE_ATTR(unexport, 0200, NULL, pwm_unexport_store); 285 286 static ssize_t npwm_show(struct device *parent, struct device_attribute *attr, 287 char *buf) 288 { 289 const struct pwm_chip *chip = dev_get_drvdata(parent); 290 291 return sprintf(buf, "%u\n", chip->npwm); 292 } 293 static DEVICE_ATTR_RO(npwm); 294 295 static struct attribute *pwm_chip_attrs[] = { 296 &dev_attr_export.attr, 297 &dev_attr_unexport.attr, 298 &dev_attr_npwm.attr, 299 NULL, 300 }; 301 ATTRIBUTE_GROUPS(pwm_chip); 302 303 static struct class pwm_class = { 304 .name = "pwm", 305 .owner = THIS_MODULE, 306 .dev_groups = pwm_chip_groups, 307 }; 308 309 static int pwmchip_sysfs_match(struct device *parent, const void *data) 310 { 311 return dev_get_drvdata(parent) == data; 312 } 313 314 void pwmchip_sysfs_export(struct pwm_chip *chip) 315 { 316 struct device *parent; 317 318 /* 319 * If device_create() fails the pwm_chip is still usable by 320 * the kernel its just not exported. 321 */ 322 parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip, 323 "pwmchip%d", chip->base); 324 if (IS_ERR(parent)) { 325 dev_warn(chip->dev, 326 "device_create failed for pwm_chip sysfs export\n"); 327 } 328 } 329 330 void pwmchip_sysfs_unexport(struct pwm_chip *chip) 331 { 332 struct device *parent; 333 334 parent = class_find_device(&pwm_class, NULL, chip, 335 pwmchip_sysfs_match); 336 if (parent) { 337 /* for class_find_device() */ 338 put_device(parent); 339 device_unregister(parent); 340 } 341 } 342 343 static int __init pwm_sysfs_init(void) 344 { 345 return class_register(&pwm_class); 346 } 347 subsys_initcall(pwm_sysfs_init); 348