drivers/pwm/sysfs.c

   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 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_get_period(pwm));
  50 }
  51
  52 static ssize_t 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_get_duty_cycle(pwm), val);
  65
  66         return ret ? : size;
  67 }
  68
  69 static ssize_t 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_get_duty_cycle(pwm));
  76 }
  77
  78 static ssize_t 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_get_period(pwm));
  91
  92         return ret ? : size;
  93 }
  94
  95 static ssize_t 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
 101         return sprintf(buf, "%d\n", pwm_is_enabled(pwm));
 102 }
 103
 104 static ssize_t enable_store(struct device *child,
 105                             struct device_attribute *attr,
 106                             const char *buf, size_t size)
 107 {
 108         struct pwm_device *pwm = child_to_pwm_device(child);
 109         int val, ret;
 110
 111         ret = kstrtoint(buf, 0, &val);
 112         if (ret)
 113                 return ret;
 114
 115         switch (val) {
 116         case 0:
 117                 pwm_disable(pwm);
 118                 break;
 119         case 1:
 120                 ret = pwm_enable(pwm);
 121                 break;
 122         default:
 123                 ret = -EINVAL;
 124                 break;
 125         }
 126
 127         return ret ? : size;
 128 }
 129
 130 static ssize_t polarity_show(struct device *child,
 131                              struct device_attribute *attr,
 132                              char *buf)
 133 {
 134         const struct pwm_device *pwm = child_to_pwm_device(child);
 135         const char *polarity = "unknown";
 136
 137         switch (pwm_get_polarity(pwm)) {
 138         case PWM_POLARITY_NORMAL:
 139                 polarity = "normal";
 140                 break;
 141
 142         case PWM_POLARITY_INVERSED:
 143                 polarity = "inversed";
 144                 break;
 145         }
 146
 147         return sprintf(buf, "%s\n", polarity);
 148 }
 149
 150 static ssize_t polarity_store(struct device *child,
 151                               struct device_attribute *attr,
 152                               const char *buf, size_t size)
 153 {
 154         struct pwm_device *pwm = child_to_pwm_device(child);
 155         enum pwm_polarity polarity;
 156         int ret;
 157
 158         if (sysfs_streq(buf, "normal"))
 159                 polarity = PWM_POLARITY_NORMAL;
 160         else if (sysfs_streq(buf, "inversed"))
 161                 polarity = PWM_POLARITY_INVERSED;
 162         else
 163                 return -EINVAL;
 164
 165         ret = pwm_set_polarity(pwm, polarity);
 166
 167         return ret ? : size;
 168 }
 169
 170 static DEVICE_ATTR_RW(period);
 171 static DEVICE_ATTR_RW(duty_cycle);
 172 static DEVICE_ATTR_RW(enable);
 173 static DEVICE_ATTR_RW(polarity);
 174
 175 static struct attribute *pwm_attrs[] = {
 176         &dev_attr_period.attr,
 177         &dev_attr_duty_cycle.attr,
 178         &dev_attr_enable.attr,
 179         &dev_attr_polarity.attr,
 180         NULL
 181 };
 182 ATTRIBUTE_GROUPS(pwm);
 183
 184 static void pwm_export_release(struct device *child)
 185 {
 186         struct pwm_export *export = child_to_pwm_export(child);
 187
 188         kfree(export);
 189 }
 190
 191 static int pwm_export_child(struct device *parent, struct pwm_device *pwm)
 192 {
 193         struct pwm_export *export;
 194         int ret;
 195
 196         if (test_and_set_bit(PWMF_EXPORTED, &pwm->flags))
 197                 return -EBUSY;
 198
 199         export = kzalloc(sizeof(*export), GFP_KERNEL);
 200         if (!export) {
 201                 clear_bit(PWMF_EXPORTED, &pwm->flags);
 202                 return -ENOMEM;
 203         }
 204
 205         export->pwm = pwm;
 206
 207         export->child.release = pwm_export_release;
 208         export->child.parent = parent;
 209         export->child.devt = MKDEV(0, 0);
 210         export->child.groups = pwm_groups;
 211         dev_set_name(&export->child, "pwm%u", pwm->hwpwm);
 212
 213         ret = device_register(&export->child);
 214         if (ret) {
 215                 clear_bit(PWMF_EXPORTED, &pwm->flags);
 216                 kfree(export);
 217                 return ret;
 218         }
 219
 220         return 0;
 221 }
 222
 223 static int pwm_unexport_match(struct device *child, void *data)
 224 {
 225         return child_to_pwm_device(child) == data;
 226 }
 227
 228 static int pwm_unexport_child(struct device *parent, struct pwm_device *pwm)
 229 {
 230         struct device *child;
 231
 232         if (!test_and_clear_bit(PWMF_EXPORTED, &pwm->flags))
 233                 return -ENODEV;
 234
 235         child = device_find_child(parent, pwm, pwm_unexport_match);
 236         if (!child)
 237                 return -ENODEV;
 238
 239         /* for device_find_child() */
 240         put_device(child);
 241         device_unregister(child);
 242         pwm_put(pwm);
 243
 244         return 0;
 245 }
 246
 247 static ssize_t export_store(struct device *parent,
 248                             struct device_attribute *attr,
 249                             const char *buf, size_t len)
 250 {
 251         struct pwm_chip *chip = dev_get_drvdata(parent);
 252         struct pwm_device *pwm;
 253         unsigned int hwpwm;
 254         int ret;
 255
 256         ret = kstrtouint(buf, 0, &hwpwm);
 257         if (ret < 0)
 258                 return ret;
 259
 260         if (hwpwm >= chip->npwm)
 261                 return -ENODEV;
 262
 263         pwm = pwm_request_from_chip(chip, hwpwm, "sysfs");
 264         if (IS_ERR(pwm))
 265                 return PTR_ERR(pwm);
 266
 267         ret = pwm_export_child(parent, pwm);
 268         if (ret < 0)
 269                 pwm_put(pwm);
 270
 271         return ret ? : len;
 272 }
 273 static DEVICE_ATTR_WO(export);
 274
 275 static ssize_t unexport_store(struct device *parent,
 276                               struct device_attribute *attr,
 277                               const char *buf, size_t len)
 278 {
 279         struct pwm_chip *chip = dev_get_drvdata(parent);
 280         unsigned int hwpwm;
 281         int ret;
 282
 283         ret = kstrtouint(buf, 0, &hwpwm);
 284         if (ret < 0)
 285                 return ret;
 286
 287         if (hwpwm >= chip->npwm)
 288                 return -ENODEV;
 289
 290         ret = pwm_unexport_child(parent, &chip->pwms[hwpwm]);
 291
 292         return ret ? : len;
 293 }
 294 static DEVICE_ATTR_WO(unexport);
 295
 296 static ssize_t npwm_show(struct device *parent, struct device_attribute *attr,
 297                          char *buf)
 298 {
 299         const struct pwm_chip *chip = dev_get_drvdata(parent);
 300
 301         return sprintf(buf, "%u\n", chip->npwm);
 302 }
 303 static DEVICE_ATTR_RO(npwm);
 304
 305 static struct attribute *pwm_chip_attrs[] = {
 306         &dev_attr_export.attr,
 307         &dev_attr_unexport.attr,
 308         &dev_attr_npwm.attr,
 309         NULL,
 310 };
 311 ATTRIBUTE_GROUPS(pwm_chip);
 312
 313 static struct class pwm_class = {
 314         .name = "pwm",
 315         .owner = THIS_MODULE,
 316         .dev_groups = pwm_chip_groups,
 317 };
 318
 319 static int pwmchip_sysfs_match(struct device *parent, const void *data)
 320 {
 321         return dev_get_drvdata(parent) == data;
 322 }
 323
 324 void pwmchip_sysfs_export(struct pwm_chip *chip)
 325 {
 326         struct device *parent;
 327
 328         /*
 329          * If device_create() fails the pwm_chip is still usable by
 330          * the kernel its just not exported.
 331          */
 332         parent = device_create(&pwm_class, chip->dev, MKDEV(0, 0), chip,
 333                                "pwmchip%d", chip->base);
 334         if (IS_ERR(parent)) {
 335                 dev_warn(chip->dev,
 336                          "device_create failed for pwm_chip sysfs export\n");
 337         }
 338 }
 339
 340 void pwmchip_sysfs_unexport(struct pwm_chip *chip)
 341 {
 342         struct device *parent;
 343
 344         parent = class_find_device(&pwm_class, NULL, chip,
 345                                    pwmchip_sysfs_match);
 346         if (parent) {
 347                 /* for class_find_device() */
 348                 put_device(parent);
 349                 device_unregister(parent);
 350         }
 351 }
 352
 353 static int __init pwm_sysfs_init(void)
 354 {
 355         return class_register(&pwm_class);
 356 }
 357 subsys_initcall(pwm_sysfs_init);