| /* |
| * 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. |
| */ |
| |
| #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 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 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; |
| } |
| |
| /* 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_async *async) |
| { |
| struct comedi_buf_map *bm = async->buf_map; |
| |
| return bm && (atomic_read(&bm->refcount.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 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_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_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_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_GPL(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_GPL(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_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; |
| } |
| |
| /* 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_GPL(comedi_buf_read_free); |
| |
| int comedi_buf_put(struct comedi_async *async, unsigned short x) |
| { |
| unsigned int n = __comedi_buf_write_alloc(async, sizeof(short), 1); |
| |
| if (n < sizeof(short)) { |
| async->events |= COMEDI_CB_ERROR; |
| return 0; |
| } |
| *(unsigned short *)(async->prealloc_buf + async->buf_write_ptr) = x; |
| comedi_buf_write_free(async, sizeof(short)); |
| return 1; |
| } |
| EXPORT_SYMBOL_GPL(comedi_buf_put); |
| |
| int comedi_buf_get(struct comedi_async *async, unsigned 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 = *(unsigned short *)(async->prealloc_buf + async->buf_read_ptr); |
| comedi_buf_read_free(async, sizeof(short)); |
| return 1; |
| } |
| EXPORT_SYMBOL_GPL(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_GPL(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_GPL(comedi_buf_memcpy_from); |