On Thu, Apr 9, 2015 at 8:15 PM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote: > On 06/04/15 15:18, Daniel Baluta wrote: >> This module is the core of IIO configfs. It creates the "iio" subsystem under >> configfs mount point root, with one default group for "triggers". >> >> It offers basic interface for registering software trigger types. Next patches >> will add "hrtimer" and "sysfs" trigger types. To add a new trigger type we must >> create a new kernel module which implements iio_configfs_trigger.h interface. >> >> See Documentation/iio/iio_configfs.txt for more details on how configfs >> support for IIO works. >> >> Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxxxx> > Looks good and is actually a fair bit simpler than I expected which is nice! > As an ideal aim, I'd like there to be no need for the core to have any > idea what triggers exist and can be registered (beyond preventing naming > clashes etc). Actually, not much would be needed to implement that I think, just > using a list and looking up in it (we aren't on a particularly fast path so > don't need anything clever) instead of a simple array. A touch of locking > probably to avoid two many simultaneous users of that list... Good point. Will do. I will create a list holding the list with the registered trigger types using the trigger type name as the searching key (e.g. : "hrtimer", "sysfs"). > > Hmm. having read through the patches, are we fundamentally limited to having to > specify the entire directory structure before bringing up configfs? AFAIK, directories can be created in two ways: * as default groups registered at iio trigger configfs init time. * when userspace applications call mkdir. So, unless we agree that userspace applications should be aware of IIO trigger types and manually call mkdir /config/iio/triggers/hrtimer (for example) we are limited to specifying the entire directory structure in the IIO configs module. > >> --- >> >> Changes since v2: >> * Fix build errors by compiling industrialio-configfs.ko >> as a separate module, as reported by Paul. >> >> Changes since v1: >> * addressed feedback from v1: >> * https://lkml.org/lkml/2015/3/25/647 >> * create a directory per trigger type >> * removed activate and type attributes >> >> drivers/iio/Kconfig | 8 ++ >> drivers/iio/Makefile | 1 + >> drivers/iio/industrialio-configfs.c | 127 +++++++++++++++++++++++++++++++ >> include/linux/iio/iio_configfs_trigger.h | 40 ++++++++++ >> 4 files changed, 176 insertions(+) >> create mode 100644 drivers/iio/industrialio-configfs.c >> create mode 100644 include/linux/iio/iio_configfs_trigger.h >> >> diff --git a/drivers/iio/Kconfig b/drivers/iio/Kconfig >> index 4011eff..41d5863 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 698afc2..72e85c42 100644 >> --- a/drivers/iio/Makefile >> +++ b/drivers/iio/Makefile >> @@ -8,6 +8,7 @@ industrialio-$(CONFIG_IIO_BUFFER) += industrialio-buffer.o >> industrialio-$(CONFIG_IIO_TRIGGER) += industrialio-trigger.o >> industrialio-$(CONFIG_IIO_BUFFER_CB) += buffer_cb.o >> >> +obj-$(CONFIG_IIO_CONFIGFS) += industrialio-configfs.o >> obj-$(CONFIG_IIO_TRIGGERED_BUFFER) += industrialio-triggered-buffer.o >> obj-$(CONFIG_IIO_KFIFO_BUF) += kfifo_buf.o >> >> diff --git a/drivers/iio/industrialio-configfs.c b/drivers/iio/industrialio-configfs.c >> new file mode 100644 >> index 0000000..d8ffd76 >> --- /dev/null >> +++ b/drivers/iio/industrialio-configfs.c >> @@ -0,0 +1,127 @@ >> +/* >> + * 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/iio_configfs_trigger.h> >> + >> +static struct iio_configfs_trigger_type *trigger_types[IIO_TRIGGER_TYPE_MAX]; >> +static DEFINE_RWLOCK(trigger_types_lock); >> + >> +int register_configfs_trigger(struct iio_configfs_trigger_type *t) >> +{ >> + int index = t->type; >> + int ret = 0; >> + >> + if (index < 0 || index >= IIO_TRIGGER_TYPE_MAX) >> + return -EINVAL; >> + >> + write_lock(&trigger_types_lock); >> + if (trigger_types[index]) >> + ret = -EBUSY; >> + else >> + trigger_types[index] = t; >> + write_unlock(&trigger_types_lock); >> + >> + return ret; >> +} >> +EXPORT_SYMBOL(register_configfs_trigger); >> + >> +int unregister_configfs_trigger(struct iio_configfs_trigger_type *t) >> +{ >> + int index = t->type; >> + >> + if (index < 0 || index >= IIO_TRIGGER_TYPE_MAX) >> + return -EINVAL; >> + >> + write_lock(&trigger_types_lock); >> + trigger_types[index] = NULL; >> + write_unlock(&trigger_types_lock); >> + >> + return 0; >> +} >> +EXPORT_SYMBOL(unregister_configfs_trigger); >> + >> +static >> +struct iio_configfs_trigger_type *iio_get_configfs_trigger_type(int type) >> +{ >> + struct iio_configfs_trigger_type *t; >> + >> + if (type < 0 || type >= IIO_TRIGGER_TYPE_MAX) >> + return ERR_PTR(-EINVAL); >> + >> + read_lock(&trigger_types_lock); >> + t = trigger_types[type]; >> + if (t && !try_module_get(t->owner)) >> + t = NULL; >> + read_unlock(&trigger_types_lock); >> + >> + return t; >> +} >> + >> +static struct config_group *iio_triggers_default_groups[] = { >> + NULL >> +}; >> + >> +static struct config_item_type iio_triggers_group_type = { >> + .ct_owner = THIS_MODULE, >> +}; >> + >> +static struct config_group iio_triggers_group = { >> + .cg_item = { >> + .ci_namebuf = "triggers", >> + .ci_type = &iio_triggers_group_type, >> + }, >> + .default_groups = iio_triggers_default_groups, >> +}; >> + >> +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@xxxxxxxxx>"); >> +MODULE_DESCRIPTION("Industrial I/O configfs support"); >> +MODULE_LICENSE("GPL v2"); >> diff --git a/include/linux/iio/iio_configfs_trigger.h b/include/linux/iio/iio_configfs_trigger.h >> new file mode 100644 >> index 0000000..75e76f2 >> --- /dev/null >> +++ b/include/linux/iio/iio_configfs_trigger.h >> @@ -0,0 +1,40 @@ >> +#ifndef __IIO_CONFIGFS_TRIGGER >> +#define __IIO_CONFIGFS_TRIGGER >> + >> +#include <linux/device.h> >> +#include <linux/iio/iio.h> >> +#include <linux/module.h> >> + >> +#define module_iio_configfs_trigger_driver(__iio_configfs_trigger) \ >> + module_driver(__iio_configfs_trigger, register_configfs_trigger, \ >> + unregister_configfs_trigger) >> + >> +enum { > Is this enum actually needed as such? If we can avoid explicit need > to list triggers in one place it would be nice. > > As I understand it, the point of this is to allow allocating of various > arrays for easy lookup etc. How about we switch over to a list and > lookup based on magic provided by the trigger? (string or address most likely). Not really needed, I was trying to avoid a list traversal. You have good point here, I will use a list with the trigger type name (string) as a search key. >> + IIO_TRIGGER_TYPE_MAX, >> +}; >> + >> +struct iio_configfs_trigger_ops; >> + >> +struct iio_configfs_trigger_type { >> + int type; >> + struct module *owner; >> + struct iio_configfs_trigger_ops *trigger_ops; >> +}; >> + >> +struct iio_configfs_trigger_info { >> + char *name; >> + struct iio_trigger *trigger; >> + struct iio_configfs_trigger_type *trigger_type; >> +}; >> + >> +struct iio_configfs_trigger_ops { > I wonder if we can make these more flexible from the start because > avoiding churn in callbacks is always nice as us ensuring we have > a manageable number in the long run! Also we might want to play > the 'fixed point' games we play elsewhere in IIO to allow us to have > a very wide range of precisions. Will try, this configfs_trigger_paramtype looks promising. > enum iio_configfs_trigger_paramtype = { > delay, > }; > > As a final thought, we have standardised on sampling_frequency elsewhere in > IIO (largely based on that was what the first few device used) so perhaps > we can use that here as well instead of delay? I am not sure I understand what is the "fixed point" game but I tried to avoid conversions from sampling_frequency integer.fractional part to timer period by using delay. As already said sampling frequency comes natural for devices and delay for timers. > > int (*get_parameter)(struct iio_configfs_trigger_info *, enum iio_configfs_triger_paramtype param, unsigned long *); > >> + int (*get_delay)(struct iio_configfs_trigger_info *, unsigned long *); >> + int (*set_delay)(struct iio_configfs_trigger_info *, unsigned long); >> + int (*probe)(struct iio_configfs_trigger_info *); >> + int (*remove)(struct iio_configfs_trigger_info *); >> +}; >> + >> +int register_configfs_trigger(struct iio_configfs_trigger_type *); >> +int unregister_configfs_trigger(struct iio_configfs_trigger_type *); >> + >> +#endif /* __IIO_CONFIGFS_TRIGGER */ >> > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
