1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Support for polling mode for input devices. 4 */ 5 6 #include <linux/device.h> 7 #include <linux/input.h> 8 #include <linux/jiffies.h> 9 #include <linux/mutex.h> 10 #include <linux/slab.h> 11 #include <linux/types.h> 12 #include <linux/workqueue.h> 13 #include "input-poller.h" 14 15 struct input_dev_poller { 16 void (*poll)(struct input_dev *dev); 17 18 unsigned int poll_interval; /* msec */ 19 unsigned int poll_interval_max; /* msec */ 20 unsigned int poll_interval_min; /* msec */ 21 22 struct input_dev *input; 23 struct delayed_work work; 24 }; 25 26 static void input_dev_poller_queue_work(struct input_dev_poller *poller) 27 { 28 unsigned long delay; 29 30 delay = msecs_to_jiffies(poller->poll_interval); 31 if (delay >= HZ) 32 delay = round_jiffies_relative(delay); 33 34 queue_delayed_work(system_freezable_wq, &poller->work, delay); 35 } 36 37 static void input_dev_poller_work(struct work_struct *work) 38 { 39 struct input_dev_poller *poller = 40 container_of(work, struct input_dev_poller, work.work); 41 42 poller->poll(poller->input); 43 input_dev_poller_queue_work(poller); 44 } 45 46 void input_dev_poller_finalize(struct input_dev_poller *poller) 47 { 48 if (!poller->poll_interval) 49 poller->poll_interval = 500; 50 if (!poller->poll_interval_max) 51 poller->poll_interval_max = poller->poll_interval; 52 } 53 54 void input_dev_poller_start(struct input_dev_poller *poller) 55 { 56 /* Only start polling if polling is enabled */ 57 if (poller->poll_interval > 0) { 58 poller->poll(poller->input); 59 input_dev_poller_queue_work(poller); 60 } 61 } 62 63 void input_dev_poller_stop(struct input_dev_poller *poller) 64 { 65 cancel_delayed_work_sync(&poller->work); 66 } 67 68 int input_setup_polling(struct input_dev *dev, 69 void (*poll_fn)(struct input_dev *dev)) 70 { 71 struct input_dev_poller *poller; 72 73 poller = kzalloc(sizeof(*poller), GFP_KERNEL); 74 if (!poller) { 75 /* 76 * We want to show message even though kzalloc() may have 77 * printed backtrace as knowing what instance of input 78 * device we were dealing with is helpful. 79 */ 80 dev_err(dev->dev.parent ?: &dev->dev, 81 "%s: unable to allocate poller structure\n", __func__); 82 return -ENOMEM; 83 } 84 85 INIT_DELAYED_WORK(&poller->work, input_dev_poller_work); 86 poller->input = dev; 87 poller->poll = poll_fn; 88 89 dev->poller = poller; 90 return 0; 91 } 92 EXPORT_SYMBOL(input_setup_polling); 93 94 static bool input_dev_ensure_poller(struct input_dev *dev) 95 { 96 if (!dev->poller) { 97 dev_err(dev->dev.parent ?: &dev->dev, 98 "poller structure has not been set up\n"); 99 return false; 100 } 101 102 return true; 103 } 104 105 void input_set_poll_interval(struct input_dev *dev, unsigned int interval) 106 { 107 if (input_dev_ensure_poller(dev)) 108 dev->poller->poll_interval = interval; 109 } 110 EXPORT_SYMBOL(input_set_poll_interval); 111 112 void input_set_min_poll_interval(struct input_dev *dev, unsigned int interval) 113 { 114 if (input_dev_ensure_poller(dev)) 115 dev->poller->poll_interval_min = interval; 116 } 117 EXPORT_SYMBOL(input_set_min_poll_interval); 118 119 void input_set_max_poll_interval(struct input_dev *dev, unsigned int interval) 120 { 121 if (input_dev_ensure_poller(dev)) 122 dev->poller->poll_interval_max = interval; 123 } 124 EXPORT_SYMBOL(input_set_max_poll_interval); 125 126 /* SYSFS interface */ 127 128 static ssize_t input_dev_get_poll_interval(struct device *dev, 129 struct device_attribute *attr, 130 char *buf) 131 { 132 struct input_dev *input = to_input_dev(dev); 133 134 return sprintf(buf, "%d\n", input->poller->poll_interval); 135 } 136 137 static ssize_t input_dev_set_poll_interval(struct device *dev, 138 struct device_attribute *attr, 139 const char *buf, size_t count) 140 { 141 struct input_dev *input = to_input_dev(dev); 142 struct input_dev_poller *poller = input->poller; 143 unsigned int interval; 144 int err; 145 146 err = kstrtouint(buf, 0, &interval); 147 if (err) 148 return err; 149 150 if (interval < poller->poll_interval_min) 151 return -EINVAL; 152 153 if (interval > poller->poll_interval_max) 154 return -EINVAL; 155 156 mutex_lock(&input->mutex); 157 158 poller->poll_interval = interval; 159 160 if (input->users) { 161 cancel_delayed_work_sync(&poller->work); 162 if (poller->poll_interval > 0) 163 input_dev_poller_queue_work(poller); 164 } 165 166 mutex_unlock(&input->mutex); 167 168 return count; 169 } 170 171 static DEVICE_ATTR(poll, 0644, 172 input_dev_get_poll_interval, input_dev_set_poll_interval); 173 174 static ssize_t input_dev_get_poll_max(struct device *dev, 175 struct device_attribute *attr, char *buf) 176 { 177 struct input_dev *input = to_input_dev(dev); 178 179 return sprintf(buf, "%d\n", input->poller->poll_interval_max); 180 } 181 182 static DEVICE_ATTR(max, 0444, input_dev_get_poll_max, NULL); 183 184 static ssize_t input_dev_get_poll_min(struct device *dev, 185 struct device_attribute *attr, char *buf) 186 { 187 struct input_dev *input = to_input_dev(dev); 188 189 return sprintf(buf, "%d\n", input->poller->poll_interval_min); 190 } 191 192 static DEVICE_ATTR(min, 0444, input_dev_get_poll_min, NULL); 193 194 static umode_t input_poller_attrs_visible(struct kobject *kobj, 195 struct attribute *attr, int n) 196 { 197 struct device *dev = kobj_to_dev(kobj); 198 struct input_dev *input = to_input_dev(dev); 199 200 return input->poller ? attr->mode : 0; 201 } 202 203 static struct attribute *input_poller_attrs[] = { 204 &dev_attr_poll.attr, 205 &dev_attr_max.attr, 206 &dev_attr_min.attr, 207 NULL 208 }; 209 210 struct attribute_group input_poller_attribute_group = { 211 .is_visible = input_poller_attrs_visible, 212 .attrs = input_poller_attrs, 213 }; 214