On 26/04/15 20:32, Daniel Baluta wrote: > On Sun, Apr 26, 2015 at 10:21 PM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote: >> 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@xxxxxxxxx> >> Looks sensible. >> My only real question is if the rwlock is justified (vs a mutex). > > Hmm, a given iio_trigger_type list element is mostly read. Also, borrowed > the code from file systems core implementation. > > http://lxr.linux.no/linux+v3.19.1/fs/filesystems.c#L33 > > Anyhow, there is no problem to use a mutex. It it's the standard option for this usecase then I don't really mind. > >> >>> --- >>> 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... > > I see your point. Could change the code to use a mutex. > >>> + >>> +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). > > I see, we can do this later. Anyhow, I'm not convinced that EAGAIN is a good > value here. We just want to inform the user that the module registering this > trigger type is already loaded. > > Like here: > > http://lxr.linux.no/linux+v3.19.1/fs/filesystems.c#L78 > Gah. I got this backwards. Ignore me on that one. > >>> + 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 */ >>> >> >> -- >> 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
