1 /* 2 * Copyright 2016 Jonathan Cameron <jic23@kernel.org> 3 * 4 * Licensed under the GPL-2. 5 * 6 * Based on a mashup of the hrtimer trigger and continuous sampling proposal of 7 * Gregor Boirie <gregor.boirie@parrot.com> 8 * 9 * Note this is still rather experimental and may eat babies. 10 * 11 * Todo 12 * * Protect against connection of devices that 'need' the top half 13 * handler. 14 * * Work out how to run top half handlers in this context if it is 15 * safe to do so (timestamp grabbing for example) 16 * 17 * Tested against a max1363. Used about 33% cpu for the thread and 20% 18 * for generic_buffer piping to /dev/null. Watermark set at 64 on a 128 19 * element kfifo buffer. 20 */ 21 22 #include <linux/kernel.h> 23 #include <linux/module.h> 24 #include <linux/platform_device.h> 25 #include <linux/slab.h> 26 #include <linux/irq_work.h> 27 #include <linux/kthread.h> 28 #include <linux/freezer.h> 29 30 #include <linux/iio/iio.h> 31 #include <linux/iio/trigger.h> 32 #include <linux/iio/sw_trigger.h> 33 34 struct iio_loop_info { 35 struct iio_sw_trigger swt; 36 struct task_struct *task; 37 }; 38 39 static struct config_item_type iio_loop_type = { 40 .ct_owner = THIS_MODULE, 41 }; 42 43 static int iio_loop_thread(void *data) 44 { 45 struct iio_trigger *trig = data; 46 47 set_freezable(); 48 49 do { 50 iio_trigger_poll_chained(trig); 51 } while (likely(!kthread_freezable_should_stop(NULL))); 52 53 return 0; 54 } 55 56 static int iio_loop_trigger_set_state(struct iio_trigger *trig, bool state) 57 { 58 struct iio_loop_info *loop_trig = iio_trigger_get_drvdata(trig); 59 60 if (state) { 61 loop_trig->task = kthread_run(iio_loop_thread, 62 trig, trig->name); 63 if (unlikely(IS_ERR(loop_trig->task))) { 64 dev_err(&trig->dev, 65 "failed to create trigger loop thread\n"); 66 return PTR_ERR(loop_trig->task); 67 } 68 } else { 69 kthread_stop(loop_trig->task); 70 } 71 72 return 0; 73 } 74 75 static const struct iio_trigger_ops iio_loop_trigger_ops = { 76 .set_trigger_state = iio_loop_trigger_set_state, 77 .owner = THIS_MODULE, 78 }; 79 80 static struct iio_sw_trigger *iio_trig_loop_probe(const char *name) 81 { 82 struct iio_loop_info *trig_info; 83 int ret; 84 85 trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL); 86 if (!trig_info) 87 return ERR_PTR(-ENOMEM); 88 89 trig_info->swt.trigger = iio_trigger_alloc("%s", name); 90 if (!trig_info->swt.trigger) { 91 ret = -ENOMEM; 92 goto err_free_trig_info; 93 } 94 95 iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info); 96 trig_info->swt.trigger->ops = &iio_loop_trigger_ops; 97 98 ret = iio_trigger_register(trig_info->swt.trigger); 99 if (ret) 100 goto err_free_trigger; 101 102 iio_swt_group_init_type_name(&trig_info->swt, name, &iio_loop_type); 103 104 return &trig_info->swt; 105 106 err_free_trigger: 107 iio_trigger_free(trig_info->swt.trigger); 108 err_free_trig_info: 109 kfree(trig_info); 110 111 return ERR_PTR(ret); 112 } 113 114 static int iio_trig_loop_remove(struct iio_sw_trigger *swt) 115 { 116 struct iio_loop_info *trig_info; 117 118 trig_info = iio_trigger_get_drvdata(swt->trigger); 119 120 iio_trigger_unregister(swt->trigger); 121 iio_trigger_free(swt->trigger); 122 kfree(trig_info); 123 124 return 0; 125 } 126 127 static const struct iio_sw_trigger_ops iio_trig_loop_ops = { 128 .probe = iio_trig_loop_probe, 129 .remove = iio_trig_loop_remove, 130 }; 131 132 static struct iio_sw_trigger_type iio_trig_loop = { 133 .name = "loop", 134 .owner = THIS_MODULE, 135 .ops = &iio_trig_loop_ops, 136 }; 137 138 module_iio_sw_trigger_driver(iio_trig_loop); 139 140 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>"); 141 MODULE_DESCRIPTION("Loop based trigger for the iio subsystem"); 142 MODULE_LICENSE("GPL v2"); 143 MODULE_ALIAS("platform:iio-trig-loop"); 144