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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | // SPDX-License-Identifier: GPL-2.0-only /* * Copyright 2016 Jonathan Cameron <jic23@kernel.org> * * Based on a mashup of the hrtimer trigger and continuous sampling proposal of * Gregor Boirie <gregor.boirie@parrot.com> * * Note this is still rather experimental and may eat babies. * * Todo * * Protect against connection of devices that 'need' the top half * handler. * * Work out how to run top half handlers in this context if it is * safe to do so (timestamp grabbing for example) * * Tested against a max1363. Used about 33% cpu for the thread and 20% * for generic_buffer piping to /dev/null. Watermark set at 64 on a 128 * element kfifo buffer. */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/platform_device.h> #include <linux/slab.h> #include <linux/irq_work.h> #include <linux/kthread.h> #include <linux/freezer.h> #include <linux/iio/iio.h> #include <linux/iio/trigger.h> #include <linux/iio/sw_trigger.h> struct iio_loop_info { struct iio_sw_trigger swt; struct task_struct *task; }; static const struct config_item_type iio_loop_type = { .ct_owner = THIS_MODULE, }; static int iio_loop_thread(void *data) { struct iio_trigger *trig = data; set_freezable(); do { iio_trigger_poll_chained(trig); } while (likely(!kthread_freezable_should_stop(NULL))); return 0; } static int iio_loop_trigger_set_state(struct iio_trigger *trig, bool state) { struct iio_loop_info *loop_trig = iio_trigger_get_drvdata(trig); if (state) { loop_trig->task = kthread_run(iio_loop_thread, trig, trig->name); if (IS_ERR(loop_trig->task)) { dev_err(&trig->dev, "failed to create trigger loop thread\n"); return PTR_ERR(loop_trig->task); } } else { kthread_stop(loop_trig->task); } return 0; } static const struct iio_trigger_ops iio_loop_trigger_ops = { .set_trigger_state = iio_loop_trigger_set_state, }; static struct iio_sw_trigger *iio_trig_loop_probe(const char *name) { struct iio_loop_info *trig_info; int ret; trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL); if (!trig_info) return ERR_PTR(-ENOMEM); trig_info->swt.trigger = iio_trigger_alloc(NULL, "%s", name); if (!trig_info->swt.trigger) { ret = -ENOMEM; goto err_free_trig_info; } iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info); trig_info->swt.trigger->ops = &iio_loop_trigger_ops; ret = iio_trigger_register(trig_info->swt.trigger); if (ret) goto err_free_trigger; iio_swt_group_init_type_name(&trig_info->swt, name, &iio_loop_type); return &trig_info->swt; err_free_trigger: iio_trigger_free(trig_info->swt.trigger); err_free_trig_info: kfree(trig_info); return ERR_PTR(ret); } static int iio_trig_loop_remove(struct iio_sw_trigger *swt) { struct iio_loop_info *trig_info; trig_info = iio_trigger_get_drvdata(swt->trigger); iio_trigger_unregister(swt->trigger); iio_trigger_free(swt->trigger); kfree(trig_info); return 0; } static const struct iio_sw_trigger_ops iio_trig_loop_ops = { .probe = iio_trig_loop_probe, .remove = iio_trig_loop_remove, }; static struct iio_sw_trigger_type iio_trig_loop = { .name = "loop", .owner = THIS_MODULE, .ops = &iio_trig_loop_ops, }; module_iio_sw_trigger_driver(iio_trig_loop); MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>"); MODULE_DESCRIPTION("Loop based trigger for the iio subsystem"); MODULE_LICENSE("GPL v2"); MODULE_ALIAS("platform:iio-trig-loop"); |