5 Commits

Author	SHA1	Message	Date
Lars-Peter Clausen	48b66f8f93	iio: Add hardware consumer buffer support ... Hardware consumer interface can be used when one IIO device has a direct connection to another device in hardware. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@st.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Mark Brown <broonie@kernel.org>	2018-01-10 10:30:05 +00:00
Greg Kroah-Hartman	b24413180f	License cleanup: add SPDX GPL-2.0 license identifier to files with no license ... Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>	2017-11-02 11:10:55 +01:00
Lars-Peter Clausen	2d6ca60f32	iio: Add a DMAengine framework based buffer ... Add a generic fully device independent DMA buffer implementation that uses the DMAegnine framework to perform the DMA transfers. This can be used by converter drivers that whish to provide a DMA buffer for converters that are connected to a DMA core that implements the DMAengine API. Apart from allocating the buffer using iio_dmaengine_buffer_alloc() and freeing it using iio_dmaengine_buffer_free() no additional converter driver specific code is required when using this DMA buffer implementation. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>	2015-10-25 13:55:32 +00:00
Lars-Peter Clausen	670b19ae9b	iio: Add generic DMA buffer infrastructure ... The traditional approach used in IIO to implement buffered capture requires the generation of at least one interrupt per sample. In the interrupt handler the driver reads the sample from the device and copies it to a software buffer. This approach has a rather large per sample overhead associated with it. And while it works fine for samplerates in the range of up to 1000 samples per second it starts to consume a rather large share of the available CPU processing time once we go beyond that, this is especially true on an embedded system with limited processing power. The regular interrupt also causes increased power consumption by not allowing the hardware into deeper sleep states, which is something that becomes more and more important on mobile battery powered devices. And while the recently added watermark support mitigates some of the issues by allowing the device to generate interrupts at a rate lower than the data output rate, this still requires a storage buffer inside the device and even if it exists it is only a few 100 samples deep at most. DMA support on the other hand allows to capture multiple millions or even more samples without any CPU interaction. This allows the CPU to either go to sleep for longer periods or focus on other tasks which increases overall system performance and power consumption. In addition to that some devices might not even offer a way to read the data other than using DMA, which makes DMA mandatory to use for them. The tasks involved in implementing a DMA buffer can be divided into two categories. The first category is memory buffer management (allocation, mapping, etc.) and hooking this up the IIO buffer callbacks like read(), enable(), disable(), etc. The second category of tasks is to setup the DMA hardware and manage the DMA transfers. Tasks from the first category will be very similar for all IIO drivers supporting DMA buffers, while the tasks from the second category will be hardware specific. This patch implements a generic infrastructure that take care of the former tasks. It provides a set of functions that implement the standard IIO buffer iio_buffer_access_funcs callbacks. These can either be used as is or be overloaded and augmented with driver specific code where necessary. For the DMA buffer support infrastructure that is introduced in this series sample data is grouped by so called blocks. A block is the basic unit at which data is exchanged between the application and the hardware. The application is responsible for allocating the memory associated with the block and then passes the block to the hardware. When the hardware has captured the amount of samples equal to size of a block it will notify the application, which can then read the data from the block and process it. The block size can freely chosen (within the constraints of the hardware). This allows to make a trade-off between latency and management overhead. The larger the block size the lower the per sample overhead but the latency between when the data was captured and when the application will be able to access it increases, in a similar way smaller block sizes have a larger per sample management overhead but a lower latency. The ideal block size thus depends on system and application requirements. For the time being the infrastructure only implements a simple double buffered scheme which allocates two blocks each with half the size of the configured buffer size. This provides basic support for capturing continuous uninterrupted data over the existing file-IO ABI. Future extensions to the DMA buffer infrastructure will give applications a more fine grained control over how many blocks are allocated and the size of each block. But this requires userspace ABI additions which are intentionally not part of this patch and will be added separately. Tasks of the second category need to be implemented by a device specific driver. They can be hooked up into the generic infrastructure using two simple callbacks, submit() and abort(). The submit() callback is used to schedule DMA transfers for blocks. Once a DMA transfer has been completed it is expected that the buffer driver calls iio_dma_buffer_block_done() to notify. The abort() callback is used for stopping all pending and active DMA transfers when the buffer is disabled. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>	2015-10-25 13:54:34 +00:00
Lars-Peter Clausen	8548a63b37	iio: Move generic buffer implementations to sub-directory ... For generic IIO trigger implementations we already have a sub-directory, but the generic buffer implementations currently reside in the IIO top-level directory. The main reason is that things have historically grown into this form. With more generic buffer implementations on its way now is the perfect time to clean this up and introduce a sub-directory for generic buffer implementations to avoid too much clutter in the top-level directory. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Signed-off-by: Jonathan Cameron <jic23@kernel.org>	2015-08-16 10:51:21 +01:00