diff options
Diffstat (limited to '')
-rw-r--r-- | drivers/iio/trigger/iio-trig-loop.c | 142 |
1 files changed, 142 insertions, 0 deletions
diff --git a/drivers/iio/trigger/iio-trig-loop.c b/drivers/iio/trigger/iio-trig-loop.c new file mode 100644 index 000000000..94a90e0a3 --- /dev/null +++ b/drivers/iio/trigger/iio-trig-loop.c @@ -0,0 +1,142 @@ +/* + * Copyright 2016 Jonathan Cameron <jic23@kernel.org> + * + * Licensed under the GPL-2. + * + * 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 (unlikely(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("%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"); |