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Date: Sun, 26 Apr 2015 20:39:25 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Daniel Baluta <daniel.baluta@...el.com>
CC: Joel Becker <jlbec@...lplan.org>,
Lars-Peter Clausen <lars@...afoo.de>,
Hartmut Knaack <knaack.h@....de>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"linux-iio@...r.kernel.org" <linux-iio@...r.kernel.org>,
"octavian.purdila@...el.com" <octavian.purdila@...el.com>,
Paul Bolle <pebolle@...cali.nl>, patrick.porlan@...el.com,
adriana.reus@...el.com, constantin.musca@...el.com,
marten@...uitiveaerial.com
Subject: Re: [PATCH v4 2/4] iio: core: Introduce IIO configfs support
On 26/04/15 20:36, Daniel Baluta wrote:
> On Sun, Apr 26, 2015 at 10:26 PM, Jonathan Cameron <jic23@...nel.org> wrote:
>> On 20/04/15 15:02, Daniel Baluta wrote:
>>> This creates an IIO configfs subystem named "iio", with a default "triggers"
>>> group.
>>>
>>> Triggers group is used for handling software triggers. To create a new software
>>> trigger one must create a directory inside the trigger directory.
>>>
>>> Software trigger name MUST follow the following convention:
>>> * <trigger-type>-<trigger-name>
>>> Where:
>>> * <trigger_type>, specifies the interrupt source (e.g: hrtimer)
>>> * <trigger-name>, specifies the IIO device trigger name
>>>
>>> Failing to follow this convention will result in an directory creation error.
>>>
>>> E.g, assuming that hrtimer trigger type is registered with IIO software
>>> trigger core:
>>>
>>> $ mkdir /config/iio/triggers/hrtimer-instance1
>>>
>>> Signed-off-by: Daniel Baluta <daniel.baluta@...el.com>
>> Looks good. Couple of little comments inline.
>>
>> Jonathan
>>> ---
>>> drivers/iio/Kconfig | 8 +++
>>> drivers/iio/Makefile | 1 +
>>> drivers/iio/industrialio-configfs.c | 117 ++++++++++++++++++++++++++++++++++++
>>> 3 files changed, 126 insertions(+)
>>> create mode 100644 drivers/iio/industrialio-configfs.c
>>>
>>> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig
>>> index de7f1d9..c310156 100644
>>> --- a/drivers/iio/Kconfig
>>> +++ b/drivers/iio/Kconfig
>>> @@ -18,6 +18,14 @@ config IIO_BUFFER
>>> Provide core support for various buffer based data
>>> acquisition methods.
>>>
>>> +config IIO_CONFIGFS
>>> + tristate "Enable IIO configuration via configfs"
>>> + select CONFIGFS_FS
>>> + help
>>> + This allows configuring various IIO bits through configfs
>>> + (e.g. software triggers). For more info see
>>> + Documentation/iio/iio_configfs.txt.
>>> +
>>> if IIO_BUFFER
>>>
>>> config IIO_BUFFER_CB
>>> diff --git a/drivers/iio/Makefile b/drivers/iio/Makefile
>>> index df87975..31aead3 100644
>>> --- a/drivers/iio/Makefile
>>> +++ b/drivers/iio/Makefile
>>> @@ -10,6 +10,7 @@ industrialio-$(CONFIG_IIO_SW_TRIGGER) += industrialio-sw-trigger.o
>>> industrialio-$(CONFIG_IIO_BUFFER_CB) += buffer_cb.o
>>>
>>> obj-$(CONFIG_IIO_TRIGGERED_BUFFER) += industrialio-triggered-buffer.o
>>> +obj-$(CONFIG_IIO_CONFIGFS) += industrialio-configfs.o
>>> obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o
>>>
>>> obj-y += accel/
>>> diff --git a/drivers/iio/industrialio-configfs.c b/drivers/iio/industrialio-configfs.c
>>> new file mode 100644
>>> index 0000000..0361434
>>> --- /dev/null
>>> +++ b/drivers/iio/industrialio-configfs.c
>>> @@ -0,0 +1,117 @@
>>> +/*
>>> + * Industrial I/O configfs bits
>>> + *
>>> + * 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/configfs.h>
>>> +#include <linux/module.h>
>>> +#include <linux/init.h>
>>> +#include <linux/kmod.h>
>>> +#include <linux/slab.h>
>>> +
>>> +#include <linux/iio/iio.h>
>>> +#include <linux/iio/sw_trigger.h>
>>> +
>>> +#define MAX_NAME_LEN 32
>> Strikes me as perhaps a little short given we want to allow 'almost' arbitary names for the triggers.
>
> We are anyhow, limited by the configfs name len here.
>
> http://lxr.linux.no/linux+v3.19.1/include/linux/configfs.h#L47
>
Fair enough. Missed that.
>
>>> +
>>> +static struct config_group *trigger_make_group(struct config_group *group,
>>> + const char *name)
>>> +{
>>> + char *type_name;
>>> + char *trigger_name;
>>> + char buf[MAX_NAME_LEN];
>>> + struct iio_sw_trigger *t;
>>> +
>>> + snprintf(buf, MAX_NAME_LEN, "%s", name);
>>> +
>>> + /* group name should have the form <trigger-type>-<trigger-name> */
>>> + type_name = buf;
>>> + trigger_name = strchr(buf, '-');
>>> + if (!trigger_name) {
>>> + pr_err("Unable to locate '-' in %s. Use <type>-<name>.\n", buf);
>>> + return ERR_PTR(-EINVAL);
>>> + }
>>> +
>>> + /* replace - with \0, this nicely separates the two strings */
>>> + *trigger_name = '\0';
>> Dirty trick, but I like it.
>
> Me too, I borrowed it from the usb gadget code. :)
>
>>> + trigger_name++;
>>> +
>>> + t = iio_sw_trigger_create(type_name, trigger_name);
>>> + if (IS_ERR(t))
>>> + return ERR_CAST(t);
>>> +
>>> + config_item_set_name(&t->group.cg_item, name);
>>> +
>>> + return &t->group;
>>> +}
>>> +
>>> +static void trigger_drop_group(struct config_group *group,
>>> + struct config_item *item)
>>> +{
>>> + struct iio_sw_trigger *t = to_iio_sw_trigger(item);
>>> +
>>> + if (t)
>>> + iio_sw_trigger_destroy(t);
>>> + config_item_put(item);
>>> +}
>>> +
>>> +static struct configfs_group_operations triggers_ops = {
>>> + .make_group = &trigger_make_group,
>>> + .drop_item = &trigger_drop_group,
>>> +};
>>> +
>>> +static struct config_item_type iio_triggers_group_type = {
>>> + .ct_group_ops = &triggers_ops,
>>> + .ct_owner = THIS_MODULE,
>>> +};
>>> +
>>> +static struct config_group iio_triggers_group = {
>>> + .cg_item = {
>>> + .ci_namebuf = "triggers",
>>> + .ci_type = &iio_triggers_group_type,
>>> + },
>>> +};
>>> +
>>> +static struct config_group *iio_root_default_groups[] = {
>>> + &iio_triggers_group,
>>> + NULL
>>> +};
>>> +
>>> +static struct config_item_type iio_root_group_type = {
>>> + .ct_owner = THIS_MODULE,
>>> +};
>>> +
>>> +static struct configfs_subsystem iio_configfs_subsys = {
>>> + .su_group = {
>>> + .cg_item = {
>>> + .ci_namebuf = "iio",
>>> + .ci_type = &iio_root_group_type,
>>> + },
>>> + .default_groups = iio_root_default_groups,
>>> + },
>>> + .su_mutex = __MUTEX_INITIALIZER(iio_configfs_subsys.su_mutex),
>>> +};
>>> +
>>> +static int __init iio_configfs_init(void)
>>> +{
>>> + config_group_init(&iio_triggers_group);
>>> + config_group_init(&iio_configfs_subsys.su_group);
>>> +
>>> + return configfs_register_subsystem(&iio_configfs_subsys);
>>> +}
>>> +module_init(iio_configfs_init);
>>> +
>>> +static void __exit iio_configfs_exit(void)
>>> +{
>>> + configfs_unregister_subsystem(&iio_configfs_subsys);
>>> +}
>>> +module_exit(iio_configfs_exit);
>>> +
>>> +MODULE_AUTHOR("Daniel Baluta <daniel.baluta@...el.com>");
>>> +MODULE_DESCRIPTION("Industrial I/O configfs support");
>>> +MODULE_LICENSE("GPL v2");
>
>
> thanks,
> Daniel.
>
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