| /* |
| * comedi_buf.c |
| * |
| * COMEDI - Linux Control and Measurement Device Interface |
| * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org> |
| * Copyright (C) 2002 Frank Mori Hess <fmhess@users.sourceforge.net> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| */ |
| |
| #include <linux/vmalloc.h> |
| #include <linux/slab.h> |
| |
| #include "comedidev.h" |
| #include "comedi_internal.h" |
| |
| #ifdef PAGE_KERNEL_NOCACHE |
| #define COMEDI_PAGE_PROTECTION PAGE_KERNEL_NOCACHE |
| #else |
| #define COMEDI_PAGE_PROTECTION PAGE_KERNEL |
| #endif |
| |
| static void comedi_buf_map_kref_release(struct kref *kref) |
| { |
| struct comedi_buf_map *bm = |
| container_of(kref, struct comedi_buf_map, refcount); |
| struct comedi_buf_page *buf; |
| unsigned int i; |
| |
| if (bm->page_list) { |
| for (i = 0; i < bm->n_pages; i++) { |
| buf = &bm->page_list[i]; |
| clear_bit(PG_reserved, |
| &(virt_to_page(buf->virt_addr)->flags)); |
| if (bm->dma_dir != DMA_NONE) { |
| #ifdef CONFIG_HAS_DMA |
| dma_free_coherent(bm->dma_hw_dev, |
| PAGE_SIZE, |
| buf->virt_addr, |
| buf->dma_addr); |
| #endif |
| } else { |
| free_page((unsigned long)buf->virt_addr); |
| } |
| } |
| vfree(bm->page_list); |
| } |
| if (bm->dma_dir != DMA_NONE) |
| put_device(bm->dma_hw_dev); |
| kfree(bm); |
| } |
| |
| static void __comedi_buf_free(struct comedi_device *dev, |
| struct comedi_subdevice *s) |
| { |
| struct comedi_async *async = s->async; |
| struct comedi_buf_map *bm; |
| unsigned long flags; |
| |
| if (async->prealloc_buf) { |
| vunmap(async->prealloc_buf); |
| async->prealloc_buf = NULL; |
| async->prealloc_bufsz = 0; |
| } |
| |
| spin_lock_irqsave(&s->spin_lock, flags); |
| bm = async->buf_map; |
| async->buf_map = NULL; |
| spin_unlock_irqrestore(&s->spin_lock, flags); |
| comedi_buf_map_put(bm); |
| } |
| |
| static void __comedi_buf_alloc(struct comedi_device *dev, |
| struct comedi_subdevice *s, |
| unsigned int n_pages) |
| { |
| struct comedi_async *async = s->async; |
| struct page **pages = NULL; |
| struct comedi_buf_map *bm; |
| struct comedi_buf_page *buf; |
| unsigned long flags; |
| unsigned int i; |
| |
| if (!IS_ENABLED(CONFIG_HAS_DMA) && s->async_dma_dir != DMA_NONE) { |
| dev_err(dev->class_dev, |
| "dma buffer allocation not supported\n"); |
| return; |
| } |
| |
| bm = kzalloc(sizeof(*async->buf_map), GFP_KERNEL); |
| if (!bm) |
| return; |
| |
| kref_init(&bm->refcount); |
| spin_lock_irqsave(&s->spin_lock, flags); |
| async->buf_map = bm; |
| spin_unlock_irqrestore(&s->spin_lock, flags); |
| bm->dma_dir = s->async_dma_dir; |
| if (bm->dma_dir != DMA_NONE) |
| /* Need ref to hardware device to free buffer later. */ |
| bm->dma_hw_dev = get_device(dev->hw_dev); |
| |
| bm->page_list = vzalloc(sizeof(*buf) * n_pages); |
| if (bm->page_list) |
| pages = vmalloc(sizeof(struct page *) * n_pages); |
| |
| if (!pages) |
| return; |
| |
| for (i = 0; i < n_pages; i++) { |
| buf = &bm->page_list[i]; |
| if (bm->dma_dir != DMA_NONE) |
| #ifdef CONFIG_HAS_DMA |
| buf->virt_addr = dma_alloc_coherent(bm->dma_hw_dev, |
| PAGE_SIZE, |
| &buf->dma_addr, |
| GFP_KERNEL | |
| __GFP_COMP); |
| #else |
| break; |
| #endif |
| else |
| buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL); |
| if (!buf->virt_addr) |
| break; |
| |
| set_bit(PG_reserved, &(virt_to_page(buf->virt_addr)->flags)); |
| |
| pages[i] = virt_to_page(buf->virt_addr); |
| } |
| spin_lock_irqsave(&s->spin_lock, flags); |
| bm->n_pages = i; |
| spin_unlock_irqrestore(&s->spin_lock, flags); |
| |
| /* vmap the prealloc_buf if all the pages were allocated */ |
| if (i == n_pages) |
| async->prealloc_buf = vmap(pages, n_pages, VM_MAP, |
| COMEDI_PAGE_PROTECTION); |
| |
| vfree(pages); |
| } |
| |
| void comedi_buf_map_get(struct comedi_buf_map *bm) |
| { |
| if (bm) |
| kref_get(&bm->refcount); |
| } |
| |
| int comedi_buf_map_put(struct comedi_buf_map *bm) |
| { |
| if (bm) |
| return kref_put(&bm->refcount, comedi_buf_map_kref_release); |
| return 1; |
| } |
| |
| /* helper for "access" vm operation */ |
| int comedi_buf_map_access(struct comedi_buf_map *bm, unsigned long offset, |
| void *buf, int len, int write) |
| { |
| unsigned int pgoff = offset_in_page(offset); |
| unsigned long pg = offset >> PAGE_SHIFT; |
| int done = 0; |
| |
| while (done < len && pg < bm->n_pages) { |
| int l = min_t(int, len - done, PAGE_SIZE - pgoff); |
| void *b = bm->page_list[pg].virt_addr + pgoff; |
| |
| if (write) |
| memcpy(b, buf, l); |
| else |
| memcpy(buf, b, l); |
| buf += l; |
| done += l; |
| pg++; |
| pgoff = 0; |
| } |
| return done; |
| } |
| |
| /* returns s->async->buf_map and increments its kref refcount */ |
| struct comedi_buf_map * |
| comedi_buf_map_from_subdev_get(struct comedi_subdevice *s) |
| { |
| struct comedi_async *async = s->async; |
| struct comedi_buf_map *bm = NULL; |
| unsigned long flags; |
| |
| if (!async) |
| return NULL; |
| |
| spin_lock_irqsave(&s->spin_lock, flags); |
| bm = async->buf_map; |
| /* only want it if buffer pages allocated */ |
| if (bm && bm->n_pages) |
| comedi_buf_map_get(bm); |
| else |
| bm = NULL; |
| spin_unlock_irqrestore(&s->spin_lock, flags); |
| |
| return bm; |
| } |
| |
| bool comedi_buf_is_mmapped(struct comedi_subdevice *s) |
| { |
| struct comedi_buf_map *bm = s->async->buf_map; |
| |
| return bm && (kref_read(&bm->refcount) > 1); |
| } |
| |
| int comedi_buf_alloc(struct comedi_device *dev, struct comedi_subdevice *s, |
| unsigned long new_size) |
| { |
| struct comedi_async *async = s->async; |
| |
| /* Round up new_size to multiple of PAGE_SIZE */ |
| new_size = (new_size + PAGE_SIZE - 1) & PAGE_MASK; |
| |
| /* if no change is required, do nothing */ |
| if (async->prealloc_buf && async->prealloc_bufsz == new_size) |
| return 0; |
| |
| /* deallocate old buffer */ |
| __comedi_buf_free(dev, s); |
| |
| /* allocate new buffer */ |
| if (new_size) { |
| unsigned int n_pages = new_size >> PAGE_SHIFT; |
| |
| __comedi_buf_alloc(dev, s, n_pages); |
| |
| if (!async->prealloc_buf) { |
| /* allocation failed */ |
| __comedi_buf_free(dev, s); |
| return -ENOMEM; |
| } |
| } |
| async->prealloc_bufsz = new_size; |
| |
| return 0; |
| } |
| |
| void comedi_buf_reset(struct comedi_subdevice *s) |
| { |
| struct comedi_async *async = s->async; |
| |
| async->buf_write_alloc_count = 0; |
| async->buf_write_count = 0; |
| async->buf_read_alloc_count = 0; |
| async->buf_read_count = 0; |
| |
| async->buf_write_ptr = 0; |
| async->buf_read_ptr = 0; |
| |
| async->cur_chan = 0; |
| async->scans_done = 0; |
| async->scan_progress = 0; |
| async->munge_chan = 0; |
| async->munge_count = 0; |
| async->munge_ptr = 0; |
| |
| async->events = 0; |
| } |
| |
| static unsigned int comedi_buf_write_n_unalloc(struct comedi_subdevice *s) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; |
| |
| return free_end - async->buf_write_alloc_count; |
| } |
| |
| unsigned int comedi_buf_write_n_available(struct comedi_subdevice *s) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; |
| |
| return free_end - async->buf_write_count; |
| } |
| |
| /** |
| * comedi_buf_write_alloc() - Reserve buffer space for writing |
| * @s: COMEDI subdevice. |
| * @nbytes: Maximum space to reserve in bytes. |
| * |
| * Reserve up to @nbytes bytes of space to be written in the COMEDI acquisition |
| * data buffer associated with the subdevice. The amount reserved is limited |
| * by the space available. |
| * |
| * Return: The amount of space reserved in bytes. |
| */ |
| unsigned int comedi_buf_write_alloc(struct comedi_subdevice *s, |
| unsigned int nbytes) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int unalloc = comedi_buf_write_n_unalloc(s); |
| |
| if (nbytes > unalloc) |
| nbytes = unalloc; |
| |
| async->buf_write_alloc_count += nbytes; |
| |
| /* |
| * ensure the async buffer 'counts' are read and updated |
| * before we write data to the write-alloc'ed buffer space |
| */ |
| smp_mb(); |
| |
| return nbytes; |
| } |
| EXPORT_SYMBOL_GPL(comedi_buf_write_alloc); |
| |
| /* |
| * munging is applied to data by core as it passes between user |
| * and kernel space |
| */ |
| static unsigned int comedi_buf_munge(struct comedi_subdevice *s, |
| unsigned int num_bytes) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int count = 0; |
| const unsigned int num_sample_bytes = comedi_bytes_per_sample(s); |
| |
| if (!s->munge || (async->cmd.flags & CMDF_RAWDATA)) { |
| async->munge_count += num_bytes; |
| count = num_bytes; |
| } else { |
| /* don't munge partial samples */ |
| num_bytes -= num_bytes % num_sample_bytes; |
| while (count < num_bytes) { |
| int block_size = num_bytes - count; |
| unsigned int buf_end; |
| |
| buf_end = async->prealloc_bufsz - async->munge_ptr; |
| if (block_size > buf_end) |
| block_size = buf_end; |
| |
| s->munge(s->device, s, |
| async->prealloc_buf + async->munge_ptr, |
| block_size, async->munge_chan); |
| |
| /* |
| * ensure data is munged in buffer before the |
| * async buffer munge_count is incremented |
| */ |
| smp_wmb(); |
| |
| async->munge_chan += block_size / num_sample_bytes; |
| async->munge_chan %= async->cmd.chanlist_len; |
| async->munge_count += block_size; |
| async->munge_ptr += block_size; |
| async->munge_ptr %= async->prealloc_bufsz; |
| count += block_size; |
| } |
| } |
| |
| return count; |
| } |
| |
| unsigned int comedi_buf_write_n_allocated(struct comedi_subdevice *s) |
| { |
| struct comedi_async *async = s->async; |
| |
| return async->buf_write_alloc_count - async->buf_write_count; |
| } |
| |
| /** |
| * comedi_buf_write_free() - Free buffer space after it is written |
| * @s: COMEDI subdevice. |
| * @nbytes: Maximum space to free in bytes. |
| * |
| * Free up to @nbytes bytes of space previously reserved for writing in the |
| * COMEDI acquisition data buffer associated with the subdevice. The amount of |
| * space freed is limited to the amount that was reserved. The freed space is |
| * assumed to have been filled with sample data by the writer. |
| * |
| * If the samples in the freed space need to be "munged", do so here. The |
| * freed space becomes available for allocation by the reader. |
| * |
| * Return: The amount of space freed in bytes. |
| */ |
| unsigned int comedi_buf_write_free(struct comedi_subdevice *s, |
| unsigned int nbytes) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int allocated = comedi_buf_write_n_allocated(s); |
| |
| if (nbytes > allocated) |
| nbytes = allocated; |
| |
| async->buf_write_count += nbytes; |
| async->buf_write_ptr += nbytes; |
| comedi_buf_munge(s, async->buf_write_count - async->munge_count); |
| if (async->buf_write_ptr >= async->prealloc_bufsz) |
| async->buf_write_ptr %= async->prealloc_bufsz; |
| |
| return nbytes; |
| } |
| EXPORT_SYMBOL_GPL(comedi_buf_write_free); |
| |
| /** |
| * comedi_buf_read_n_available() - Determine amount of readable buffer space |
| * @s: COMEDI subdevice. |
| * |
| * Determine the amount of readable buffer space in the COMEDI acquisition data |
| * buffer associated with the subdevice. The readable buffer space is that |
| * which has been freed by the writer and "munged" to the sample data format |
| * expected by COMEDI if necessary. |
| * |
| * Return: The amount of readable buffer space. |
| */ |
| unsigned int comedi_buf_read_n_available(struct comedi_subdevice *s) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int num_bytes; |
| |
| if (!async) |
| return 0; |
| |
| num_bytes = async->munge_count - async->buf_read_count; |
| |
| /* |
| * ensure the async buffer 'counts' are read before we |
| * attempt to read data from the buffer |
| */ |
| smp_rmb(); |
| |
| return num_bytes; |
| } |
| EXPORT_SYMBOL_GPL(comedi_buf_read_n_available); |
| |
| /** |
| * comedi_buf_read_alloc() - Reserve buffer space for reading |
| * @s: COMEDI subdevice. |
| * @nbytes: Maximum space to reserve in bytes. |
| * |
| * Reserve up to @nbytes bytes of previously written and "munged" buffer space |
| * for reading in the COMEDI acquisition data buffer associated with the |
| * subdevice. The amount reserved is limited to the space available. The |
| * reader can read from the reserved space and then free it. A reader is also |
| * allowed to read from the space before reserving it as long as it determines |
| * the amount of readable data available, but the space needs to be marked as |
| * reserved before it can be freed. |
| * |
| * Return: The amount of space reserved in bytes. |
| */ |
| unsigned int comedi_buf_read_alloc(struct comedi_subdevice *s, |
| unsigned int nbytes) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int available; |
| |
| available = async->munge_count - async->buf_read_alloc_count; |
| if (nbytes > available) |
| nbytes = available; |
| |
| async->buf_read_alloc_count += nbytes; |
| |
| /* |
| * ensure the async buffer 'counts' are read before we |
| * attempt to read data from the read-alloc'ed buffer space |
| */ |
| smp_rmb(); |
| |
| return nbytes; |
| } |
| EXPORT_SYMBOL_GPL(comedi_buf_read_alloc); |
| |
| static unsigned int comedi_buf_read_n_allocated(struct comedi_async *async) |
| { |
| return async->buf_read_alloc_count - async->buf_read_count; |
| } |
| |
| /** |
| * comedi_buf_read_free() - Free buffer space after it has been read |
| * @s: COMEDI subdevice. |
| * @nbytes: Maximum space to free in bytes. |
| * |
| * Free up to @nbytes bytes of buffer space previously reserved for reading in |
| * the COMEDI acquisition data buffer associated with the subdevice. The |
| * amount of space freed is limited to the amount that was reserved. |
| * |
| * The freed space becomes available for allocation by the writer. |
| * |
| * Return: The amount of space freed in bytes. |
| */ |
| unsigned int comedi_buf_read_free(struct comedi_subdevice *s, |
| unsigned int nbytes) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int allocated; |
| |
| /* |
| * ensure data has been read out of buffer before |
| * the async read count is incremented |
| */ |
| smp_mb(); |
| |
| allocated = comedi_buf_read_n_allocated(async); |
| if (nbytes > allocated) |
| nbytes = allocated; |
| |
| async->buf_read_count += nbytes; |
| async->buf_read_ptr += nbytes; |
| async->buf_read_ptr %= async->prealloc_bufsz; |
| return nbytes; |
| } |
| EXPORT_SYMBOL_GPL(comedi_buf_read_free); |
| |
| static void comedi_buf_memcpy_to(struct comedi_subdevice *s, |
| const void *data, unsigned int num_bytes) |
| { |
| struct comedi_async *async = s->async; |
| unsigned int write_ptr = async->buf_write_ptr; |
| |
| while (num_bytes) { |
| unsigned int block_size; |
| |
| if (write_ptr + num_bytes > async->prealloc_bufsz) |
| block_size = async->prealloc_bufsz - write_ptr; |
| else |
| block_size = num_bytes; |
| |
| memcpy(async->prealloc_buf + write_ptr, data, block_size); |
| |
| data += block_size; |
| num_bytes -= block_size; |
| |
| write_ptr = 0; |
| } |
| } |
| |
| static void comedi_buf_memcpy_from(struct comedi_subdevice *s, |
| void *dest, unsigned int nbytes) |
| { |
| void *src; |
| struct comedi_async *async = s->async; |
| unsigned int read_ptr = async->buf_read_ptr; |
| |
| while (nbytes) { |
| unsigned int block_size; |
| |
| src = async->prealloc_buf + read_ptr; |
| |
| if (nbytes >= async->prealloc_bufsz - read_ptr) |
| block_size = async->prealloc_bufsz - read_ptr; |
| else |
| block_size = nbytes; |
| |
| memcpy(dest, src, block_size); |
| nbytes -= block_size; |
| dest += block_size; |
| read_ptr = 0; |
| } |
| } |
| |
| /** |
| * comedi_buf_write_samples() - Write sample data to COMEDI buffer |
| * @s: COMEDI subdevice. |
| * @data: Pointer to source samples. |
| * @nsamples: Number of samples to write. |
| * |
| * Write up to @nsamples samples to the COMEDI acquisition data buffer |
| * associated with the subdevice, mark it as written and update the |
| * acquisition scan progress. If there is not enough room for the specified |
| * number of samples, the number of samples written is limited to the number |
| * that will fit and the %COMEDI_CB_OVERFLOW event flag is set to cause the |
| * acquisition to terminate with an overrun error. Set the %COMEDI_CB_BLOCK |
| * event flag if any samples are written to cause waiting tasks to be woken |
| * when the event flags are processed. |
| * |
| * Return: The amount of data written in bytes. |
| */ |
| unsigned int comedi_buf_write_samples(struct comedi_subdevice *s, |
| const void *data, unsigned int nsamples) |
| { |
| unsigned int max_samples; |
| unsigned int nbytes; |
| |
| /* |
| * Make sure there is enough room in the buffer for all the samples. |
| * If not, clamp the nsamples to the number that will fit, flag the |
| * buffer overrun and add the samples that fit. |
| */ |
| max_samples = comedi_bytes_to_samples(s, comedi_buf_write_n_unalloc(s)); |
| if (nsamples > max_samples) { |
| dev_warn(s->device->class_dev, "buffer overrun\n"); |
| s->async->events |= COMEDI_CB_OVERFLOW; |
| nsamples = max_samples; |
| } |
| |
| if (nsamples == 0) |
| return 0; |
| |
| nbytes = comedi_buf_write_alloc(s, |
| comedi_samples_to_bytes(s, nsamples)); |
| comedi_buf_memcpy_to(s, data, nbytes); |
| comedi_buf_write_free(s, nbytes); |
| comedi_inc_scan_progress(s, nbytes); |
| s->async->events |= COMEDI_CB_BLOCK; |
| |
| return nbytes; |
| } |
| EXPORT_SYMBOL_GPL(comedi_buf_write_samples); |
| |
| /** |
| * comedi_buf_read_samples() - Read sample data from COMEDI buffer |
| * @s: COMEDI subdevice. |
| * @data: Pointer to destination. |
| * @nsamples: Maximum number of samples to read. |
| * |
| * Read up to @nsamples samples from the COMEDI acquisition data buffer |
| * associated with the subdevice, mark it as read and update the acquisition |
| * scan progress. Limit the number of samples read to the number available. |
| * Set the %COMEDI_CB_BLOCK event flag if any samples are read to cause waiting |
| * tasks to be woken when the event flags are processed. |
| * |
| * Return: The amount of data read in bytes. |
| */ |
| unsigned int comedi_buf_read_samples(struct comedi_subdevice *s, |
| void *data, unsigned int nsamples) |
| { |
| unsigned int max_samples; |
| unsigned int nbytes; |
| |
| /* clamp nsamples to the number of full samples available */ |
| max_samples = comedi_bytes_to_samples(s, |
| comedi_buf_read_n_available(s)); |
| if (nsamples > max_samples) |
| nsamples = max_samples; |
| |
| if (nsamples == 0) |
| return 0; |
| |
| nbytes = comedi_buf_read_alloc(s, |
| comedi_samples_to_bytes(s, nsamples)); |
| comedi_buf_memcpy_from(s, data, nbytes); |
| comedi_buf_read_free(s, nbytes); |
| comedi_inc_scan_progress(s, nbytes); |
| s->async->events |= COMEDI_CB_BLOCK; |
| |
| return nbytes; |
| } |
| EXPORT_SYMBOL_GPL(comedi_buf_read_samples); |