these files support initilising and managing access to the shared buffers area in memory that is used to exchange data between AXD and linux
Signed-off-by: Qais Yousef qais.yousef@imgtec.com Cc: Arnd Bergmann arnd@arndb.de Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: alsa-devel@alsa-project.org --- drivers/char/axd/axd_buffers.c | 245 +++++++++++++++++++++++++++++++++++++++++ drivers/char/axd/axd_buffers.h | 70 ++++++++++++ 2 files changed, 315 insertions(+) create mode 100644 drivers/char/axd/axd_buffers.c create mode 100644 drivers/char/axd/axd_buffers.h
diff --git a/drivers/char/axd/axd_buffers.c b/drivers/char/axd/axd_buffers.c new file mode 100644 index 000000000000..fefa7f85f4db --- /dev/null +++ b/drivers/char/axd/axd_buffers.c @@ -0,0 +1,245 @@ +/* + * Copyright (C) 2011-2014 Imagination Technologies Ltd. + * + * 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. + * + * AXD generic buffer management API. + */ +#include <linux/err.h> +#include <linux/slab.h> + +#include "axd_buffers.h" + +#ifdef DEBUG_BUFFERS +#define debugbuf printk +#else +#define debugbuf(format, ...) +#endif + +/** + * axd_buffer_init - sets up axd buffer as a pool of fixed sized buffers. + * @address: starting address of the buffer as set up in the system + * @total_size: total size of available buffer + * @element_size: size of each buffer element + * + * axd_buffer_t *buffer is a memory pool of size @element_size and starting at + * address @address and of @total_size size. + */ +static int bufferq_init(struct axd_bufferq *bufferq, const char *name, + char *address, unsigned int num_elements, + unsigned int element_size, unsigned int nonblock) +{ + int i; + char **queue; + unsigned int *size; + + strncpy(bufferq->name, name, 16); + bufferq->stride = element_size; + bufferq->max = num_elements; + bufferq->rd_idx = 0; + bufferq->wr_idx = 0; + bufferq->nonblock = nonblock; + queue = kcalloc(num_elements, sizeof(char *), GFP_KERNEL); + if (!queue) + return -ENOMEM; + bufferq->queue = queue; + size = kcalloc(num_elements, sizeof(unsigned int), GFP_KERNEL); + if (!size) { + kfree(queue); + bufferq->queue = NULL; + return -ENOMEM; + } + bufferq->size = size; + /* + * setup the queue with all available buffer addresses if the base + * address is passed. Set it up as emptry if base address is NULL. + */ + if (address) { + for (i = 0; i < num_elements; i++) { + queue[i] = address + (element_size * i); + size[i] = element_size; + } + sema_init(&bufferq->rd_sem, num_elements); + sema_init(&bufferq->wr_sem, 0); + } else { + for (i = 0; i < num_elements; i++) { + queue[i] = NULL; + size[i] = element_size; + } + sema_init(&bufferq->rd_sem, 0); + sema_init(&bufferq->wr_sem, num_elements); + } + spin_lock_init(&bufferq->q_rdlock); + spin_lock_init(&bufferq->q_wrlock); + debugbuf("Initialized %s of %d elements of size %d bytes\n", + name, num_elements, element_size); + debugbuf("Address of %s: 0x%08X\n", name, (unsigned int)bufferq); + return 0; +} + +int axd_bufferq_init(struct axd_bufferq *bufferq, const char *name, + char *address, unsigned int num_elements, + unsigned int element_size, unsigned int nonblock) +{ + return bufferq_init(bufferq, + name, address, num_elements, element_size, nonblock); +} + +int axd_bufferq_init_empty(struct axd_bufferq *bufferq, const char *name, + unsigned int num_elements, unsigned int element_size, + unsigned int nonblock) +{ + return bufferq_init(bufferq, + name, NULL, num_elements, element_size, nonblock); +} + +void axd_bufferq_clear(struct axd_bufferq *bufferq) +{ + kfree(bufferq->queue); + kfree(bufferq->size); + bufferq->queue = NULL; + bufferq->size = NULL; +} + +/** + * axd_buffer_take - returns a valid buffer pointer + * @buffer: the buffers pool to be accessed + * + * This function will go into interruptible sleep if the pool is empty. + */ +char *axd_bufferq_take(struct axd_bufferq *bufferq, int *buf_size) +{ + char *buf; + int ret; + + if (!bufferq->queue) + return NULL; + + debugbuf("--(%s)-- taking new buffer\n", bufferq->name); + if (bufferq->nonblock) { + ret = down_trylock(&bufferq->rd_sem); + if (ret) + return ERR_PTR(-EAGAIN); + + } else { + ret = down_interruptible(&bufferq->rd_sem); + if (ret) + return ERR_PTR(-ERESTARTSYS); + if (bufferq->abort_take) { + bufferq->abort_take = 0; + return ERR_PTR(-ERESTARTSYS); + } + } + /* + * must ensure we have one access at a time to the queue and rd_idx + * to be preemption and SMP safe + * Sempahores will ensure that we will only read after a complete write + * has finished, so we will never read and write from the same location. + */ + spin_lock(&bufferq->q_rdlock); + buf = bufferq->queue[bufferq->rd_idx]; + if (buf_size) + *buf_size = bufferq->size[bufferq->rd_idx]; + bufferq->rd_idx++; + if (bufferq->rd_idx >= bufferq->max) + bufferq->rd_idx = 0; + spin_unlock(&bufferq->q_rdlock); + up(&bufferq->wr_sem); + debugbuf("--(%s)-- took buffer <0x%08X>\n", bufferq->name, + (unsigned int)buf); + return buf; +} + +/** + * axd_buffer_put - returns a buffer to the pool. + * @buffer: the buffers pool to be accessed + * @buf: the buffer to be returned. + * + * This function will go into interruptible sleep if the pool is full. + */ +int axd_bufferq_put(struct axd_bufferq *bufferq, char *buf, int buf_size) +{ + int ret; + + if (!bufferq->queue) + return 0; + + if (buf_size < 0) + buf_size = bufferq->stride; + + debugbuf("++(%s)++ returning buffer\n", bufferq->name); + if (bufferq->nonblock) { + ret = down_trylock(&bufferq->wr_sem); + if (ret) + return -EAGAIN; + + } else { + ret = down_interruptible(&bufferq->wr_sem); + if (ret) + return -ERESTARTSYS; + if (bufferq->abort_put) { + bufferq->abort_put = 0; + return -ERESTARTSYS; + } + } + /* + * must ensure we have one access at a time to the queue and wr_idx + * to be preemption and SMP safe. + * Semaphores will ensure that we only write after a complete read has + * finished, so we will never write and read from the same location. + */ + spin_lock(&bufferq->q_wrlock); + bufferq->queue[bufferq->wr_idx] = buf; + bufferq->size[bufferq->wr_idx] = buf_size; + bufferq->wr_idx++; + if (bufferq->wr_idx >= bufferq->max) + bufferq->wr_idx = 0; + spin_unlock(&bufferq->q_wrlock); + up(&bufferq->rd_sem); + debugbuf("++(%s)++ returned buffer <0x%08X>\n", bufferq->name, + (unsigned int)buf); + return 0; +} + +int axd_bufferq_is_full(struct axd_bufferq *bufferq) +{ + int ret; + /* + * if we can't put a buffer, then we're full. + */ + ret = down_trylock(&bufferq->wr_sem); + if (!ret) + up(&bufferq->wr_sem); + return ret; +} + +int axd_bufferq_is_empty(struct axd_bufferq *bufferq) +{ + int ret; + /* + * if we can't take more buffers, then its empty. + */ + ret = down_trylock(&bufferq->rd_sem); + if (!ret) + up(&bufferq->rd_sem); + return ret; +} + +void axd_bufferq_abort_take(struct axd_bufferq *bufferq) +{ + if (axd_bufferq_is_empty(bufferq)) { + bufferq->abort_take = 1; + up(&bufferq->rd_sem); + } +} + +void axd_bufferq_abort_put(struct axd_bufferq *bufferq) +{ + if (axd_bufferq_is_full(bufferq)) { + bufferq->abort_put = 1; + up(&bufferq->wr_sem); + } +} diff --git a/drivers/char/axd/axd_buffers.h b/drivers/char/axd/axd_buffers.h new file mode 100644 index 000000000000..745a5e28b36f --- /dev/null +++ b/drivers/char/axd/axd_buffers.h @@ -0,0 +1,70 @@ +/* + * Copyright (C) 2011-2014 Imagination Technologies Ltd. + * + * 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. + * + * AXD generic buffer management API. + */ +#ifndef AXD_BUFFERS_H_ +#define AXD_BUFFERS_H_ + +#include <linux/semaphore.h> +#include <linux/spinlock.h> + +/** + * struct axd_bufferq - axd buffer management structure + * @name: name of the buffer queue + * @stride: the space between buffers in memory + * @max: total number of buffers this queue can handle + * @rd_idx: read index of the circular buffer + * @wr_idx: write index of the circular buffer + * @rd_sem: semaphore to block when full + * @wr_sem: semaphore to block when empty + * @q_rdlock: smp critical section protection for reads + * @q_wrlock: smp critical section protection for writes + * @queue: array of pointers to buffer addresses + * @size: array of buffer's actual amount of data it has inside or it can + * store. + * @nonblock: return an error instead of block when empty/full + * @abort_take: abort any pending blocked take operation + * @abort_put: abort any pending blocked put operation + * + * axd_bufferq takes a contiguous memory region and divides it into smaller + * buffers regions of equal size and represents it as a queue. To avoid + * excessive locking it's done as a circular buffer queue. + */ +struct axd_bufferq { + char name[16]; + unsigned int stride; + unsigned int max; + unsigned int rd_idx; + unsigned int wr_idx; + struct semaphore rd_sem; + struct semaphore wr_sem; + spinlock_t q_rdlock; + spinlock_t q_wrlock; + char **queue; + unsigned int *size; + unsigned int nonblock; + unsigned int abort_take; + unsigned int abort_put; +}; + +int axd_bufferq_init(struct axd_bufferq *bufferq, const char *name, + char *address, unsigned int num_elements, + unsigned int element_size, unsigned int nonblock); +int axd_bufferq_init_empty(struct axd_bufferq *bufferq, const char *name, + unsigned int num_elements, unsigned int element_size, + unsigned int nonblock); +void axd_bufferq_clear(struct axd_bufferq *bufferq); +char *axd_bufferq_take(struct axd_bufferq *bufferq, int *buf_size); +int axd_bufferq_put(struct axd_bufferq *bufferq, char *buf, int buf_size); +int axd_bufferq_is_full(struct axd_bufferq *bufferq); +int axd_bufferq_is_empty(struct axd_bufferq *bufferq); +void axd_bufferq_abort_take(struct axd_bufferq *bufferq); +void axd_bufferq_abort_put(struct axd_bufferq *bufferq); + +#endif /* AXD_BUFFERS_H_ */