diff options
Diffstat (limited to 'drivers/comedi/comedi_buf.c')
| -rw-r--r-- | drivers/comedi/comedi_buf.c | 692 |
1 files changed, 692 insertions, 0 deletions
diff --git a/drivers/comedi/comedi_buf.c b/drivers/comedi/comedi_buf.c new file mode 100644 index 000000000000..06bfc859ab31 --- /dev/null +++ b/drivers/comedi/comedi_buf.c @@ -0,0 +1,692 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * 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> + */ + +#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) { + if (bm->dma_dir != DMA_NONE) { + /* + * DMA buffer was allocated as a single block. + * Address is in page_list[0]. + */ + buf = &bm->page_list[0]; + dma_free_coherent(bm->dma_hw_dev, + PAGE_SIZE * bm->n_pages, + buf->virt_addr, buf->dma_addr); + } else { + for (i = 0; i < bm->n_pages; i++) { + buf = &bm->page_list[i]; + ClearPageReserved(virt_to_page(buf->virt_addr)); + 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) { + if (s->async_dma_dir == DMA_NONE) + 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 struct comedi_buf_map * +comedi_buf_map_alloc(struct comedi_device *dev, enum dma_data_direction dma_dir, + unsigned int n_pages) +{ + struct comedi_buf_map *bm; + struct comedi_buf_page *buf; + unsigned int i; + + bm = kzalloc(sizeof(*bm), GFP_KERNEL); + if (!bm) + return NULL; + + kref_init(&bm->refcount); + bm->dma_dir = 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) + goto err; + + if (bm->dma_dir != DMA_NONE) { + void *virt_addr; + dma_addr_t dma_addr; + + /* + * Currently, the DMA buffer needs to be allocated as a + * single block so that it can be mmap()'ed. + */ + virt_addr = dma_alloc_coherent(bm->dma_hw_dev, + PAGE_SIZE * n_pages, &dma_addr, + GFP_KERNEL); + if (!virt_addr) + goto err; + + for (i = 0; i < n_pages; i++) { + buf = &bm->page_list[i]; + buf->virt_addr = virt_addr + (i << PAGE_SHIFT); + buf->dma_addr = dma_addr + (i << PAGE_SHIFT); + } + + bm->n_pages = i; + } else { + for (i = 0; i < n_pages; i++) { + buf = &bm->page_list[i]; + buf->virt_addr = (void *)get_zeroed_page(GFP_KERNEL); + if (!buf->virt_addr) + break; + + SetPageReserved(virt_to_page(buf->virt_addr)); + } + + bm->n_pages = i; + if (i < n_pages) + goto err; + } + + return bm; + +err: + comedi_buf_map_put(bm); + return NULL; +} + +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 = comedi_buf_map_alloc(dev, s->async_dma_dir, n_pages); + if (!bm) + return; + + spin_lock_irqsave(&s->spin_lock, flags); + async->buf_map = bm; + spin_unlock_irqrestore(&s->spin_lock, flags); + + if (bm->dma_dir != DMA_NONE) { + /* + * DMA buffer was allocated as a single block. + * Address is in page_list[0]. + */ + buf = &bm->page_list[0]; + async->prealloc_buf = buf->virt_addr; + } else { + pages = vmalloc(sizeof(struct page *) * n_pages); + if (!pages) + return; + + for (i = 0; i < n_pages; i++) { + buf = &bm->page_list[i]; + pages[i] = virt_to_page(buf->virt_addr); + } + + /* vmap the pages to prealloc_buf */ + 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; + + lockdep_assert_held(&dev->mutex); + + /* 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; + return num_bytes; + } + + /* 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); |