diff options
Diffstat (limited to 'drivers/staging/comedi/comedi_buf.c')
| -rw-r--r-- | drivers/staging/comedi/comedi_buf.c | 415 |
1 files changed, 415 insertions, 0 deletions
diff --git a/drivers/staging/comedi/comedi_buf.c b/drivers/staging/comedi/comedi_buf.c new file mode 100644 index 000000000000..9b997ae67796 --- /dev/null +++ b/drivers/staging/comedi/comedi_buf.c @@ -0,0 +1,415 @@ +/* + * comedi_buf.c + * + * COMEDI - Linux Control and Measurement Device Interface + * Copyright (C) 1997-2000 David A. Schleef <ds@schleef.org> + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + */ + +#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_free(struct comedi_device *dev, + struct comedi_subdevice *s, + unsigned n_pages) +{ + struct comedi_async *async = s->async; + struct comedi_buf_page *buf; + unsigned i; + + if (async->prealloc_buf) { + vunmap(async->prealloc_buf); + async->prealloc_buf = NULL; + async->prealloc_bufsz = 0; + } + + if (!async->buf_page_list) + return; + + for (i = 0; i < n_pages; ++i) { + buf = &async->buf_page_list[i]; + if (buf->virt_addr) { + clear_bit(PG_reserved, + &(virt_to_page(buf->virt_addr)->flags)); + if (s->async_dma_dir != DMA_NONE) { + dma_free_coherent(dev->hw_dev, + PAGE_SIZE, + buf->virt_addr, + buf->dma_addr); + } else { + free_page((unsigned long)buf->virt_addr); + } + } + } + vfree(async->buf_page_list); + async->buf_page_list = NULL; + async->n_buf_pages = 0; +} + +static void __comedi_buf_alloc(struct comedi_device *dev, + struct comedi_subdevice *s, + unsigned n_pages) +{ + struct comedi_async *async = s->async; + struct page **pages = NULL; + struct comedi_buf_page *buf; + unsigned i; + + async->buf_page_list = vzalloc(sizeof(*buf) * n_pages); + if (async->buf_page_list) + pages = vmalloc(sizeof(struct page *) * n_pages); + + if (!pages) + return; + + for (i = 0; i < n_pages; i++) { + buf = &async->buf_page_list[i]; + if (s->async_dma_dir != DMA_NONE) + buf->virt_addr = dma_alloc_coherent(dev->hw_dev, + PAGE_SIZE, + &buf->dma_addr, + GFP_KERNEL | + __GFP_COMP); + 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); + } + + /* 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); +} + +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, async->n_buf_pages); + + /* allocate new buffer */ + if (new_size) { + unsigned n_pages = new_size >> PAGE_SHIFT; + + __comedi_buf_alloc(dev, s, n_pages); + + if (!async->prealloc_buf) { + /* allocation failed */ + __comedi_buf_free(dev, s, n_pages); + return -ENOMEM; + } + async->n_buf_pages = n_pages; + } + async->prealloc_bufsz = new_size; + + return 0; +} + +void comedi_buf_reset(struct comedi_async *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->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_available(struct comedi_async *async) +{ + unsigned int free_end = async->buf_read_count + async->prealloc_bufsz; + + return free_end - async->buf_write_alloc_count; +} + +static unsigned int __comedi_buf_write_alloc(struct comedi_async *async, + unsigned int nbytes, + int strict) +{ + unsigned int available = comedi_buf_write_n_available(async); + + if (nbytes > available) + nbytes = strict ? 0 : available; + + 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; +} + +/* allocates chunk for the writer from free buffer space */ +unsigned int comedi_buf_write_alloc(struct comedi_async *async, + unsigned int nbytes) +{ + return __comedi_buf_write_alloc(async, nbytes, 0); +} +EXPORT_SYMBOL(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_async *async, + unsigned int num_bytes) +{ + struct comedi_subdevice *s = async->subdevice; + unsigned int count = 0; + const unsigned num_sample_bytes = 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_async *async) +{ + return async->buf_write_alloc_count - async->buf_write_count; +} + +/* transfers a chunk from writer to filled buffer space */ +unsigned int comedi_buf_write_free(struct comedi_async *async, + unsigned int nbytes) +{ + unsigned int allocated = comedi_buf_write_n_allocated(async); + + if (nbytes > allocated) + nbytes = allocated; + + async->buf_write_count += nbytes; + async->buf_write_ptr += nbytes; + comedi_buf_munge(async, 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(comedi_buf_write_free); + +unsigned int comedi_buf_read_n_available(struct comedi_async *async) +{ + unsigned 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(comedi_buf_read_n_available); + +/* allocates a chunk for the reader from filled (and munged) buffer space */ +unsigned int comedi_buf_read_alloc(struct comedi_async *async, + unsigned int nbytes) +{ + 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(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; +} + +/* transfers control of a chunk from reader to free buffer space */ +unsigned int comedi_buf_read_free(struct comedi_async *async, + unsigned int nbytes) +{ + 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(comedi_buf_read_free); + +int comedi_buf_put(struct comedi_async *async, short x) +{ + unsigned int n = __comedi_buf_write_alloc(async, sizeof(short), 1); + + if (n < sizeof(short)) { + async->events |= COMEDI_CB_ERROR; + return 0; + } + *(short *)(async->prealloc_buf + async->buf_write_ptr) = x; + comedi_buf_write_free(async, sizeof(short)); + return 1; +} +EXPORT_SYMBOL(comedi_buf_put); + +int comedi_buf_get(struct comedi_async *async, short *x) +{ + unsigned int n = comedi_buf_read_n_available(async); + + if (n < sizeof(short)) + return 0; + comedi_buf_read_alloc(async, sizeof(short)); + *x = *(short *)(async->prealloc_buf + async->buf_read_ptr); + comedi_buf_read_free(async, sizeof(short)); + return 1; +} +EXPORT_SYMBOL(comedi_buf_get); + +void comedi_buf_memcpy_to(struct comedi_async *async, unsigned int offset, + const void *data, unsigned int num_bytes) +{ + unsigned int write_ptr = async->buf_write_ptr + offset; + + if (write_ptr >= async->prealloc_bufsz) + write_ptr %= async->prealloc_bufsz; + + 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; + } +} +EXPORT_SYMBOL(comedi_buf_memcpy_to); + +void comedi_buf_memcpy_from(struct comedi_async *async, unsigned int offset, + void *dest, unsigned int nbytes) +{ + void *src; + unsigned int read_ptr = async->buf_read_ptr + offset; + + if (read_ptr >= async->prealloc_bufsz) + read_ptr %= async->prealloc_bufsz; + + 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; + } +} +EXPORT_SYMBOL(comedi_buf_memcpy_from); |