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Date: Sun, 26 Apr 2015 20:21:03 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Daniel Baluta <daniel.baluta@...el.com>
CC: jlbec@...lplan.org, lars@...afoo.de, knaack.h@....de,
linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
octavian.purdila@...el.com, pebolle@...cali.nl,
patrick.porlan@...el.com, adriana.reus@...el.com,
constantin.musca@...el.com, marten@...uitiveaerial.com
Subject: Re: [PATCH v4 1/4] iio: core: Introduce IIO software triggers
On 20/04/15 15:02, Daniel Baluta wrote:
> A software trigger associates an IIO device trigger with a software
> interrupt source (e.g: timer, sysfs). This patch adds the generic
> infrastructure for handling software triggers.
>
> Software interrupts sources are kept in a iio_trigger_types_list and
> registered separately when the associated kernel module is loaded.
>
> Software triggers can be created directly from drivers or from user
> space via configfs interface.
>
> Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>
Looks sensible.
My only real question is if the rwlock is justified (vs a mutex).
> ---
> drivers/iio/Kconfig | 8 +++
> drivers/iio/Makefile | 1 +
> drivers/iio/industrialio-sw-trigger.c | 111 ++++++++++++++++++++++++++++++++++
> include/linux/iio/sw_trigger.h | 50 +++++++++++++++
> 4 files changed, 170 insertions(+)
> create mode 100644 drivers/iio/industrialio-sw-trigger.c
> create mode 100644 include/linux/iio/sw_trigger.h
>
> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
> index 4011eff..de7f1d9 100644
> --- a/drivers/iio/Kconfig
> +++ b/drivers/iio/Kconfig
> @@ -58,6 +58,14 @@ config IIO_CONSUMERS_PER_TRIGGER
> This value controls the maximum number of consumers that a
> given trigger may handle. Default is 2.
>
> +config IIO_SW_TRIGGER
> + bool "Enable software triggers support"
> + depends on IIO_TRIGGER
> + help
> + Provides IIO core support for software triggers. A software
> + trigger can be created via configfs or directly by a driver
> + using the API provided.
> +
> source "drivers/iio/accel/Kconfig"
> source "drivers/iio/adc/Kconfig"
> source "drivers/iio/amplifiers/Kconfig"
> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
> index 698afc2..df87975 100644
> --- a/drivers/iio/Makefile
> +++ b/drivers/iio/Makefile
> @@ -6,6 +6,7 @@ obj-$(CONFIG_IIO) += industrialio.o
> industrialio-y := industrialio-core.o industrialio-event.o inkern.o
> industrialio-$(CONFIG_IIO_BUFFER) += industrialio-buffer.o
> industrialio-$(CONFIG_IIO_TRIGGER) += industrialio-trigger.o
> +industrialio-$(CONFIG_IIO_SW_TRIGGER) += industrialio-sw-trigger.o
> industrialio-$(CONFIG_IIO_BUFFER_CB) += buffer_cb.o
>
> obj-$(CONFIG_IIO_TRIGGERED_BUFFER) += industrialio-triggered-buffer.o
> diff --git a/drivers/iio/industrialio-sw-trigger.c b/drivers/iio/industrialio-sw-trigger.c
> new file mode 100644
> index 0000000..567c675
> --- /dev/null
> +++ b/drivers/iio/industrialio-sw-trigger.c
> @@ -0,0 +1,111 @@
> +/*
> + * The Industrial I/O core, software trigger functions
> + *
> + * Copyright (c) 2015 Intel Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published by
> + * the Free Software Foundation.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/kmod.h>
> +#include <linux/list.h>
> +#include <linux/slab.h>
> +
> +#include <linux/iio/sw_trigger.h>
> +
> +static LIST_HEAD(iio_trigger_types_list);
> +static DEFINE_RWLOCK(iio_trigger_types_lock);
Can see the logic, but I'm not totally convinced a rwlock is necessary.
We don't actually create new ones terribly often...
> +
> +static
> +struct iio_sw_trigger_type *iio_find_sw_trigger_type(char *name, unsigned len)
> +{
> + struct iio_sw_trigger_type *t = NULL, *iter;
> +
> + list_for_each_entry(iter, &iio_trigger_types_list, list)
> + if (!strncmp(iter->name, name, len)) {
> + t = iter;
> + break;
> + }
> +
> + return t;
> +}
> +
> +int iio_register_sw_trigger_type(struct iio_sw_trigger_type *t)
> +{
> + struct iio_sw_trigger_type *iter;
> + int ret = 0;
> +
> + write_lock(&iio_trigger_types_lock);
> + iter = iio_find_sw_trigger_type(t->name, strlen(t->name));
> + if (iter)
> + ret = -EBUSY;
Rather than EAGAIN? Could also do the magic attempt to autoload the
module that the usb gadget driver does (though add that as a later
feature rather than in this first posting I think to keep complexity
of patch manageable).
> + else
> + list_add_tail(&t->list, &iio_trigger_types_list);
> + write_unlock(&iio_trigger_types_lock);
nitpick :) blank line here.
> + return ret;
> +}
> +EXPORT_SYMBOL(iio_register_sw_trigger_type);
> +
> +int iio_unregister_sw_trigger_type(struct iio_sw_trigger_type *t)
> +{
> + struct iio_sw_trigger_type *iter;
> + int ret = 0;
> +
> + write_lock(&iio_trigger_types_lock);
> + iter = iio_find_sw_trigger_type(t->name, strlen(t->name));
> + if (!iter)
> + ret = -EINVAL;
> + else
> + list_del(&t->list);
> + write_unlock(&iio_trigger_types_lock);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL(iio_unregister_sw_trigger_type);
> +
> +static
> +struct iio_sw_trigger_type *iio_get_sw_trigger_type(char *name)
> +{
> + struct iio_sw_trigger_type *t;
> +
> + read_lock(&iio_trigger_types_lock);
> + t = iio_find_sw_trigger_type(name, strlen(name));
> + if (t && !try_module_get(t->owner))
> + t = NULL;
> + read_unlock(&iio_trigger_types_lock);
> +
> + return t;
> +}
> +
> +struct iio_sw_trigger *iio_sw_trigger_create(char *type, char *name)
> +{
> + struct iio_sw_trigger *t;
> + struct iio_sw_trigger_type *tt;
I like the brief variable names (perfectly clear so not actually being
sarcastic ;))
> +
> + tt = iio_get_sw_trigger_type(type);
> + if (!tt) {
> + pr_err("Invalid trigger type: %s\n", type);
> + return ERR_PTR(-EINVAL);
> + }
> + t = tt->ops->probe(name);
> + if (IS_ERR(t))
> + goto out_module_put;
> +
> + return t;
> +out_module_put:
> + module_put(tt->owner);
> + return t;
> +}
> +EXPORT_SYMBOL(iio_sw_trigger_create);
> +
> +void iio_sw_trigger_destroy(struct iio_sw_trigger *t)
> +{
> + struct iio_sw_trigger_type *tt = t->trigger_type;
> +
> + tt->ops->remove(t);
> + module_put(tt->owner);
> +}
> +EXPORT_SYMBOL(iio_sw_trigger_destroy);
> diff --git a/include/linux/iio/sw_trigger.h b/include/linux/iio/sw_trigger.h
> new file mode 100644
> index 0000000..2e6659b
> --- /dev/null
> +++ b/include/linux/iio/sw_trigger.h
> @@ -0,0 +1,50 @@
> +#ifndef __IIO_SW_TRIGGER
> +#define __IIO_SW_TRIGGER
> +
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/iio/iio.h>
> +#include <linux/configfs.h>
> +
> +#define module_iio_sw_trigger_driver(__iio_sw_trigger_type) \
> + module_driver(__iio_sw_trigger_type, iio_register_sw_trigger_type, \
> + iio_unregister_sw_trigger_type)
> +
> +struct iio_sw_trigger_ops;
> +
> +struct iio_sw_trigger_type {
> + char *name;
> + struct module *owner;
> + struct iio_sw_trigger_ops *ops;
> + struct list_head list;
> +};
> +
> +struct iio_sw_trigger {
> + struct iio_trigger *trigger;
> + struct iio_sw_trigger_type *trigger_type;
> +#ifdef CONFIG_CONFIGFS_FS
> + struct config_group group;
> +#endif
> +};
> +
> +struct iio_sw_trigger_ops {
> + struct iio_sw_trigger* (*probe)(const char *);
> + int (*remove)(struct iio_sw_trigger *);
> +};
> +
> +int iio_register_sw_trigger_type(struct iio_sw_trigger_type *);
> +int iio_unregister_sw_trigger_type(struct iio_sw_trigger_type *);
> +
> +struct iio_sw_trigger *iio_sw_trigger_create(char *, char *);
> +void iio_sw_trigger_destroy(struct iio_sw_trigger *);
> +
> +#ifdef CONFIG_CONFIGFS_FS
> +static inline
> +struct iio_sw_trigger *to_iio_sw_trigger(struct config_item *item)
> +{
> + return container_of(to_config_group(item), struct iio_sw_trigger,
> + group);
> +}
> +#endif
> +
> +#endif /* __IIO_SW_TRIGGER */
>
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