rtlx.c
/*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*
* Copyright (C) 2005 MIPS Technologies, Inc. All rights reserved.
* Copyright (C) 2005, 06 Ralf Baechle (ralf@linux-mips.org)
* Copyright (C) 2013 Imagination Technologies Ltd.
*/
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/syscalls.h>
#include <linux/moduleloader.h>
#include <linux/atomic.h>
#include <linux/sched/signal.h>
#include <asm/mipsmtregs.h>
#include <asm/mips_mt.h>
#include <asm/processor.h>
#include <asm/rtlx.h>
#include <asm/setup.h>
#include <asm/vpe.h>
static int sp_stopping;
struct rtlx_info *rtlx;
struct chan_waitqueues channel_wqs[RTLX_CHANNELS];
struct vpe_notifications rtlx_notify;
void (*aprp_hook)(void) = NULL;
EXPORT_SYMBOL(aprp_hook);
static void __used dump_rtlx(void)
{
int i;
pr_info("id 0x%lx state %d\n", rtlx->id, rtlx->state);
for (i = 0; i < RTLX_CHANNELS; i++) {
struct rtlx_channel *chan = &rtlx->channel[i];
pr_info(" rt_state %d lx_state %d buffer_size %d\n",
chan->rt_state, chan->lx_state, chan->buffer_size);
pr_info(" rt_read %d rt_write %d\n",
chan->rt_read, chan->rt_write);
pr_info(" lx_read %d lx_write %d\n",
chan->lx_read, chan->lx_write);
pr_info(" rt_buffer <%s>\n", chan->rt_buffer);
pr_info(" lx_buffer <%s>\n", chan->lx_buffer);
}
}
/* call when we have the address of the shared structure from the SP side. */
static int rtlx_init(struct rtlx_info *rtlxi)
{
if (rtlxi->id != RTLX_ID) {
pr_err("no valid RTLX id at 0x%p 0x%lx\n", rtlxi, rtlxi->id);
return -ENOEXEC;
}
rtlx = rtlxi;
return 0;
}
/* notifications */
void rtlx_starting(int vpe)
{
int i;
sp_stopping = 0;
/* force a reload of rtlx */
rtlx = NULL;
/* wake up any sleeping rtlx_open's */
for (i = 0; i < RTLX_CHANNELS; i++)
wake_up_interruptible(&channel_wqs[i].lx_queue);
}
void rtlx_stopping(int vpe)
{
int i;
sp_stopping = 1;
for (i = 0; i < RTLX_CHANNELS; i++)
wake_up_interruptible(&channel_wqs[i].lx_queue);
}
int rtlx_open(int index, int can_sleep)
{
struct rtlx_info **p;
struct rtlx_channel *chan;
enum rtlx_state state;
int ret = 0;
if (index >= RTLX_CHANNELS) {
pr_debug("rtlx_open index out of range\n");
return -ENOSYS;
}
if (atomic_inc_return(&channel_wqs[index].in_open) > 1) {
pr_debug("rtlx_open channel %d already opened\n", index);
ret = -EBUSY;
goto out_fail;
}
if (rtlx == NULL) {
p = vpe_get_shared(aprp_cpu_index());
if (p == NULL) {
if (can_sleep) {
ret = __wait_event_interruptible(
channel_wqs[index].lx_queue,
(p = vpe_get_shared(aprp_cpu_index())));
if (ret)
goto out_fail;
} else {
pr_debug("No SP program loaded, and device opened with O_NONBLOCK\n");
ret = -ENOSYS;
goto out_fail;
}
}
smp_rmb();
if (*p == NULL) {
if (can_sleep) {
DEFINE_WAIT(wait);
for (;;) {
prepare_to_wait(
&channel_wqs[index].lx_queue,
&wait, TASK_INTERRUPTIBLE);
smp_rmb();
if (*p != NULL)
break;
if (!signal_pending(current)) {
schedule();
continue;
}
ret = -ERESTARTSYS;
goto out_fail;
}
finish_wait(&channel_wqs[index].lx_queue,
&wait);
} else {
pr_err(" *vpe_get_shared is NULL. Has an SP program been loaded?\n");
ret = -ENOSYS;
goto out_fail;
}
}
if ((unsigned int)*p < KSEG0) {
pr_warn("vpe_get_shared returned an invalid pointer maybe an error code %d\n",
(int)*p);
ret = -ENOSYS;
goto out_fail;
}
ret = rtlx_init(*p);
if (ret < 0)
goto out_ret;
}
chan = &rtlx->channel[index];
state = xchg(&chan->lx_state, RTLX_STATE_OPENED);
if (state == RTLX_STATE_OPENED) {
ret = -EBUSY;
goto out_fail;
}
out_fail:
smp_mb();
atomic_dec(&channel_wqs[index].in_open);
smp_mb();
out_ret:
return ret;
}
int rtlx_release(int index)
{
if (rtlx == NULL) {
pr_err("rtlx_release() with null rtlx\n");
return 0;
}
rtlx->channel[index].lx_state = RTLX_STATE_UNUSED;
return 0;
}
unsigned int rtlx_read_poll(int index, int can_sleep)
{
struct rtlx_channel *chan;
if (rtlx == NULL)
return 0;
chan = &rtlx->channel[index];
/* data available to read? */
if (chan->lx_read == chan->lx_write) {
if (can_sleep) {
int ret = __wait_event_interruptible(
channel_wqs[index].lx_queue,
(chan->lx_read != chan->lx_write) ||
sp_stopping);
if (ret)
return ret;
if (sp_stopping)
return 0;
} else
return 0;
}
return (chan->lx_write + chan->buffer_size - chan->lx_read)
% chan->buffer_size;
}
static inline int write_spacefree(int read, int write, int size)
{
if (read == write) {
/*
* Never fill the buffer completely, so indexes are always
* equal if empty and only empty, or !equal if data available
*/
return size - 1;
}
return ((read + size - write) % size) - 1;
}
unsigned int rtlx_write_poll(int index)
{
struct rtlx_channel *chan = &rtlx->channel[index];
return write_spacefree(chan->rt_read, chan->rt_write,
chan->buffer_size);
}
ssize_t rtlx_read(int index, void __user *buff, size_t count)
{
size_t lx_write, fl = 0L;
struct rtlx_channel *lx;
unsigned long failed;
if (rtlx == NULL)
return -ENOSYS;
lx = &rtlx->channel[index];
mutex_lock(&channel_wqs[index].mutex);
smp_rmb();
lx_write = lx->lx_write;
/* find out how much in total */
count = min(count,
(size_t)(lx_write + lx->buffer_size - lx->lx_read)
% lx->buffer_size);
/* then how much from the read pointer onwards */
fl = min(count, (size_t)lx->buffer_size - lx->lx_read);
failed = copy_to_user(buff, lx->lx_buffer + lx->lx_read, fl);
if (failed)
goto out;
/* and if there is anything left at the beginning of the buffer */
if (count - fl)
failed = copy_to_user(buff + fl, lx->lx_buffer, count - fl);
out:
count -= failed;
smp_wmb();
lx->lx_read = (lx->lx_read + count) % lx->buffer_size;
smp_wmb();
mutex_unlock(&channel_wqs[index].mutex);
return count;
}
ssize_t rtlx_write(int index, const void __user *buffer, size_t count)
{
struct rtlx_channel *rt;
unsigned long failed;
size_t rt_read;
size_t fl;
if (rtlx == NULL)
return -ENOSYS;
rt = &rtlx->channel[index];
mutex_lock(&channel_wqs[index].mutex);
smp_rmb();
rt_read = rt->rt_read;
/* total number of bytes to copy */
count = min_t(size_t, count, write_spacefree(rt_read, rt->rt_write,
rt->buffer_size));
/* first bit from write pointer to the end of the buffer, or count */
fl = min(count, (size_t) rt->buffer_size - rt->rt_write);
failed = copy_from_user(rt->rt_buffer + rt->rt_write, buffer, fl);
if (failed)
goto out;
/* if there's any left copy to the beginning of the buffer */
if (count - fl)
failed = copy_from_user(rt->rt_buffer, buffer + fl, count - fl);
out:
count -= failed;
smp_wmb();
rt->rt_write = (rt->rt_write + count) % rt->buffer_size;
smp_wmb();
mutex_unlock(&channel_wqs[index].mutex);
_interrupt_sp();
return count;
}
static int file_open(struct inode *inode, struct file *filp)
{
return rtlx_open(iminor(inode), (filp->f_flags & O_NONBLOCK) ? 0 : 1);
}
static int file_release(struct inode *inode, struct file *filp)
{
return rtlx_release(iminor(inode));
}
static __poll_t file_poll(struct file *file, poll_table *wait)
{
int minor = iminor(file_inode(file));
__poll_t mask = 0;
poll_wait(file, &channel_wqs[minor].rt_queue, wait);
poll_wait(file, &channel_wqs[minor].lx_queue, wait);
if (rtlx == NULL)
return 0;
/* data available to read? */
if (rtlx_read_poll(minor, 0))
mask |= EPOLLIN | EPOLLRDNORM;
/* space to write */
if (rtlx_write_poll(minor))
mask |= EPOLLOUT | EPOLLWRNORM;
return mask;
}
static ssize_t file_read(struct file *file, char __user *buffer, size_t count,
loff_t *ppos)
{
int minor = iminor(file_inode(file));
/* data available? */
if (!rtlx_read_poll(minor, (file->f_flags & O_NONBLOCK) ? 0 : 1))
return 0; /* -EAGAIN makes 'cat' whine */
return rtlx_read(minor, buffer, count);
}
static ssize_t file_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
int minor = iminor(file_inode(file));
/* any space left... */
if (!rtlx_write_poll(minor)) {
int ret;
if (file->f_flags & O_NONBLOCK)
return -EAGAIN;
ret = __wait_event_interruptible(channel_wqs[minor].rt_queue,
rtlx_write_poll(minor));
if (ret)
return ret;
}
return rtlx_write(minor, buffer, count);
}
const struct file_operations rtlx_fops = {
.owner = THIS_MODULE,
.open = file_open,
.release = file_release,
.write = file_write,
.read = file_read,
.poll = file_poll,
.llseek = noop_llseek,
};
module_init(rtlx_module_init);
module_exit(rtlx_module_exit);
MODULE_DESCRIPTION("MIPS RTLX");
MODULE_AUTHOR("Elizabeth Oldham, MIPS Technologies, Inc.");
MODULE_LICENSE("GPL");