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Diffstat (limited to 'drivers/iio/industrialio-backend.c')
| -rw-r--r-- | drivers/iio/industrialio-backend.c | 418 |
1 files changed, 418 insertions, 0 deletions
diff --git a/drivers/iio/industrialio-backend.c b/drivers/iio/industrialio-backend.c new file mode 100644 index 00000000000000..2fea2bbbe47fd0 --- /dev/null +++ b/drivers/iio/industrialio-backend.c @@ -0,0 +1,418 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Framework to handle complex IIO aggregate devices. + * + * The typical architecture is to have one device as the frontend device which + * can be "linked" against one or multiple backend devices. All the IIO and + * userspace interface is expected to be registers/managed by the frontend + * device which will callback into the backends when needed (to get/set some + * configuration that it does not directly control). + * + * ------------------------------------------------------- + * ------------------ | ------------ ------------ ------- FPGA| + * | ADC |------------------------| | ADC CORE |---------| DMA CORE |------| RAM | | + * | (Frontend/IIO) | Serial Data (eg: LVDS) | |(backend) |---------| |------| | | + * | |------------------------| ------------ ------------ ------- | + * ------------------ ------------------------------------------------------- + * + * The framework interface is pretty simple: + * - Backends should register themselves with devm_iio_backend_register() + * - Frontend devices should get backends with devm_iio_backend_get() + * + * Also to note that the primary target for this framework are converters like + * ADC/DACs so iio_backend_ops will have some operations typical of converter + * devices. On top of that, this is "generic" for all IIO which means any kind + * of device can make use of the framework. That said, If the iio_backend_ops + * struct begins to grow out of control, we can always refactor things so that + * the industrialio-backend.c is only left with the really generic stuff. Then, + * we can build on top of it depending on the needs. + * + * Copyright (C) 2023-2024 Analog Devices Inc. + */ +#define dev_fmt(fmt) "iio-backend: " fmt + +#include <linux/cleanup.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/errno.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/property.h> +#include <linux/slab.h> +#include <linux/types.h> + +#include <linux/iio/backend.h> + +struct iio_backend { + struct list_head entry; + const struct iio_backend_ops *ops; + struct device *dev; + struct module *owner; + void *priv; +}; + +/* + * Helper struct for requesting buffers. This ensures that we have all data + * that we need to free the buffer in a device managed action. + */ +struct iio_backend_buffer_pair { + struct iio_backend *back; + struct iio_buffer *buffer; +}; + +static LIST_HEAD(iio_back_list); +static DEFINE_MUTEX(iio_back_lock); + +/* + * Helper macros to call backend ops. Makes sure the option is supported. + */ +#define iio_backend_check_op(back, op) ({ \ + struct iio_backend *____back = back; \ + int ____ret = 0; \ + \ + if (!____back->ops->op) \ + ____ret = -EOPNOTSUPP; \ + \ + ____ret; \ +}) + +#define iio_backend_op_call(back, op, args...) ({ \ + struct iio_backend *__back = back; \ + int __ret; \ + \ + __ret = iio_backend_check_op(__back, op); \ + if (!__ret) \ + __ret = __back->ops->op(__back, ##args); \ + \ + __ret; \ +}) + +#define iio_backend_ptr_op_call(back, op, args...) ({ \ + struct iio_backend *__back = back; \ + void *ptr_err; \ + int __ret; \ + \ + __ret = iio_backend_check_op(__back, op); \ + if (__ret) \ + ptr_err = ERR_PTR(__ret); \ + else \ + ptr_err = __back->ops->op(__back, ##args); \ + \ + ptr_err; \ +}) + +#define iio_backend_void_op_call(back, op, args...) { \ + struct iio_backend *__back = back; \ + int __ret; \ + \ + __ret = iio_backend_check_op(__back, op); \ + if (!__ret) \ + __back->ops->op(__back, ##args); \ +} + +/** + * iio_backend_chan_enable - Enable a backend channel + * @back: Backend device + * @chan: Channel number + * + * RETURNS: + * 0 on success, negative error number on failure. + */ +int iio_backend_chan_enable(struct iio_backend *back, unsigned int chan) +{ + return iio_backend_op_call(back, chan_enable, chan); +} +EXPORT_SYMBOL_NS_GPL(iio_backend_chan_enable, IIO_BACKEND); + +/** + * iio_backend_chan_disable - Disable a backend channel + * @back: Backend device + * @chan: Channel number + * + * RETURNS: + * 0 on success, negative error number on failure. + */ +int iio_backend_chan_disable(struct iio_backend *back, unsigned int chan) +{ + return iio_backend_op_call(back, chan_disable, chan); +} +EXPORT_SYMBOL_NS_GPL(iio_backend_chan_disable, IIO_BACKEND); + +static void __iio_backend_disable(void *back) +{ + iio_backend_void_op_call(back, disable); +} + +/** + * devm_iio_backend_enable - Device managed backend enable + * @dev: Consumer device for the backend + * @back: Backend device + * + * RETURNS: + * 0 on success, negative error number on failure. + */ +int devm_iio_backend_enable(struct device *dev, struct iio_backend *back) +{ + int ret; + + ret = iio_backend_op_call(back, enable); + if (ret) + return ret; + + return devm_add_action_or_reset(dev, __iio_backend_disable, back); +} +EXPORT_SYMBOL_NS_GPL(devm_iio_backend_enable, IIO_BACKEND); + +/** + * iio_backend_data_format_set - Configure the channel data format + * @back: Backend device + * @chan: Channel number + * @data: Data format + * + * Properly configure a channel with respect to the expected data format. A + * @struct iio_backend_data_fmt must be passed with the settings. + * + * RETURNS: + * 0 on success, negative error number on failure. + */ +int iio_backend_data_format_set(struct iio_backend *back, unsigned int chan, + const struct iio_backend_data_fmt *data) +{ + if (!data || data->type >= IIO_BACKEND_DATA_TYPE_MAX) + return -EINVAL; + + return iio_backend_op_call(back, data_format_set, chan, data); +} +EXPORT_SYMBOL_NS_GPL(iio_backend_data_format_set, IIO_BACKEND); + +static void iio_backend_free_buffer(void *arg) +{ + struct iio_backend_buffer_pair *pair = arg; + + iio_backend_void_op_call(pair->back, free_buffer, pair->buffer); +} + +/** + * devm_iio_backend_request_buffer - Device managed buffer request + * @dev: Consumer device for the backend + * @back: Backend device + * @indio_dev: IIO device + * + * Request an IIO buffer from the backend. The type of the buffer (typically + * INDIO_BUFFER_HARDWARE) is up to the backend to decide. This is because, + * normally, the backend dictates what kind of buffering we can get. + * + * The backend .free_buffer() hooks is automatically called on @dev detach. + * + * RETURNS: + * 0 on success, negative error number on failure. + */ +int devm_iio_backend_request_buffer(struct device *dev, + struct iio_backend *back, + struct iio_dev *indio_dev) +{ + struct iio_backend_buffer_pair *pair; + struct iio_buffer *buffer; + + pair = devm_kzalloc(dev, sizeof(*pair), GFP_KERNEL); + if (!pair) + return -ENOMEM; + + buffer = iio_backend_ptr_op_call(back, request_buffer, indio_dev); + if (IS_ERR(buffer)) + return PTR_ERR(buffer); + + /* weak reference should be all what we need */ + pair->back = back; + pair->buffer = buffer; + + return devm_add_action_or_reset(dev, iio_backend_free_buffer, pair); +} +EXPORT_SYMBOL_NS_GPL(devm_iio_backend_request_buffer, IIO_BACKEND); + +static void iio_backend_release(void *arg) +{ + struct iio_backend *back = arg; + + module_put(back->owner); +} + +static int __devm_iio_backend_get(struct device *dev, struct iio_backend *back) +{ + struct device_link *link; + int ret; + + /* + * Make sure the provider cannot be unloaded before the consumer module. + * Note that device_links would still guarantee that nothing is + * accessible (and breaks) but this makes it explicit that the consumer + * module must be also unloaded. + */ + if (!try_module_get(back->owner)) + return dev_err_probe(dev, -ENODEV, + "Cannot get module reference\n"); + + ret = devm_add_action_or_reset(dev, iio_backend_release, back); + if (ret) + return ret; + + link = device_link_add(dev, back->dev, DL_FLAG_AUTOREMOVE_CONSUMER); + if (!link) + return dev_err_probe(dev, -EINVAL, + "Could not link to supplier(%s)\n", + dev_name(back->dev)); + + dev_dbg(dev, "Found backend(%s) device\n", dev_name(back->dev)); + + return 0; +} + +/** + * devm_iio_backend_get - Device managed backend device get + * @dev: Consumer device for the backend + * @name: Backend name + * + * Get's the backend associated with @dev. + * + * RETURNS: + * A backend pointer, negative error pointer otherwise. + */ +struct iio_backend *devm_iio_backend_get(struct device *dev, const char *name) +{ + struct fwnode_handle *fwnode; + struct iio_backend *back; + unsigned int index; + int ret; + + if (name) { + ret = device_property_match_string(dev, "io-backend-names", + name); + if (ret < 0) + return ERR_PTR(ret); + index = ret; + } else { + index = 0; + } + + fwnode = fwnode_find_reference(dev_fwnode(dev), "io-backends", index); + if (IS_ERR(fwnode)) { + dev_err_probe(dev, PTR_ERR(fwnode), + "Cannot get Firmware reference\n"); + return ERR_CAST(fwnode); + } + + guard(mutex)(&iio_back_lock); + list_for_each_entry(back, &iio_back_list, entry) { + if (!device_match_fwnode(back->dev, fwnode)) + continue; + + fwnode_handle_put(fwnode); + ret = __devm_iio_backend_get(dev, back); + if (ret) + return ERR_PTR(ret); + + return back; + } + + fwnode_handle_put(fwnode); + return ERR_PTR(-EPROBE_DEFER); +} +EXPORT_SYMBOL_NS_GPL(devm_iio_backend_get, IIO_BACKEND); + +/** + * __devm_iio_backend_get_from_fwnode_lookup - Device managed fwnode backend device get + * @dev: Consumer device for the backend + * @fwnode: Firmware node of the backend device + * + * Search the backend list for a device matching @fwnode. + * This API should not be used and it's only present for preventing the first + * user of this framework to break it's DT ABI. + * + * RETURNS: + * A backend pointer, negative error pointer otherwise. + */ +struct iio_backend * +__devm_iio_backend_get_from_fwnode_lookup(struct device *dev, + struct fwnode_handle *fwnode) +{ + struct iio_backend *back; + int ret; + + guard(mutex)(&iio_back_lock); + list_for_each_entry(back, &iio_back_list, entry) { + if (!device_match_fwnode(back->dev, fwnode)) + continue; + + ret = __devm_iio_backend_get(dev, back); + if (ret) + return ERR_PTR(ret); + + return back; + } + + return ERR_PTR(-EPROBE_DEFER); +} +EXPORT_SYMBOL_NS_GPL(__devm_iio_backend_get_from_fwnode_lookup, IIO_BACKEND); + +/** + * iio_backend_get_priv - Get driver private data + * @back: Backend device + */ +void *iio_backend_get_priv(const struct iio_backend *back) +{ + return back->priv; +} +EXPORT_SYMBOL_NS_GPL(iio_backend_get_priv, IIO_BACKEND); + +static void iio_backend_unregister(void *arg) +{ + struct iio_backend *back = arg; + + guard(mutex)(&iio_back_lock); + list_del(&back->entry); +} + +/** + * devm_iio_backend_register - Device managed backend device register + * @dev: Backend device being registered + * @ops: Backend ops + * @priv: Device private data + * + * @ops is mandatory. Not providing it results in -EINVAL. + * + * RETURNS: + * 0 on success, negative error number on failure. + */ +int devm_iio_backend_register(struct device *dev, + const struct iio_backend_ops *ops, void *priv) +{ + struct iio_backend *back; + + if (!ops) + return dev_err_probe(dev, -EINVAL, "No backend ops given\n"); + + /* + * Through device_links, we guarantee that a frontend device cannot be + * bound/exist if the backend driver is not around. Hence, we can bind + * the backend object lifetime with the device being passed since + * removing it will tear the frontend/consumer down. + */ + back = devm_kzalloc(dev, sizeof(*back), GFP_KERNEL); + if (!back) + return -ENOMEM; + + back->ops = ops; + back->owner = dev->driver->owner; + back->dev = dev; + back->priv = priv; + scoped_guard(mutex, &iio_back_lock) + list_add(&back->entry, &iio_back_list); + + return devm_add_action_or_reset(dev, iio_backend_unregister, back); +} +EXPORT_SYMBOL_NS_GPL(devm_iio_backend_register, IIO_BACKEND); + +MODULE_AUTHOR("Nuno Sa <nuno.sa@analog.com>"); +MODULE_DESCRIPTION("Framework to handle complex IIO aggregate devices"); +MODULE_LICENSE("GPL"); |