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/* Copyright (c) 2014-2016, The Linux Foundation. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 and
* only version 2 as published by the Free Software Foundation.
*
* 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 "mhi_sys.h"
#include "mhi.h"
static int add_element(struct mhi_ring *ring, void **rp,
void **wp, void **assigned_addr)
{
uintptr_t d_wp = 0, d_rp = 0, ring_size = 0;
int r;
if (NULL == ring || 0 == ring->el_size
|| NULL == ring->base || 0 == ring->len) {
return -EINVAL;
}
r = get_element_index(ring, *rp, &d_rp);
if (r)
return r;
r = get_element_index(ring, *wp, &d_wp);
if (r)
return r;
ring_size = ring->len / ring->el_size;
if ((d_wp + 1) % ring_size == d_rp) {
if (ring->overwrite_en) {
ctxt_del_element(ring, NULL);
} else {
return -ENOSPC;
}
}
if (NULL != assigned_addr)
*assigned_addr = (char *)ring->wp;
*wp = (void *)(((d_wp + 1) % ring_size) * ring->el_size +
(uintptr_t)ring->base);
/* force update visible to other cores */
smp_wmb();
return 0;
}
inline int ctxt_add_element(struct mhi_ring *ring,
void **assigned_addr)
{
return add_element(ring, &ring->rp, &ring->wp, assigned_addr);
}
inline int ctxt_del_element(struct mhi_ring *ring,
void **assigned_addr)
{
return delete_element(ring, &ring->rp, &ring->wp, assigned_addr);
}
/**
* delete_element - Moves the read pointer of the transfer ring to
* the next element of the transfer ring,
*
* ring location of local ring data structure
* @rp ring read pointer
* @wp ring write pointer
* @assigned_addr location of the element just deleted
*/
int delete_element(struct mhi_ring *ring, void **rp,
void **wp, void **assigned_addr)
{
uintptr_t d_wp = 0, d_rp = 0, ring_size = 0;
int r;
if (NULL == ring || 0 == ring->el_size ||
NULL == ring->base || 0 == ring->len)
return -EINVAL;
ring_size = ring->len / ring->el_size;
r = get_element_index(ring, *rp, &d_rp);
if (r)
return r;
r = get_element_index(ring, *wp, &d_wp);
if (r)
return r;
if (d_wp == d_rp) {
if (NULL != assigned_addr)
*assigned_addr = NULL;
return -ENODATA;
}
if (NULL != assigned_addr)
*assigned_addr = (void *)ring->rp;
*rp = (void *)(((d_rp + 1) % ring_size) * ring->el_size +
(uintptr_t)ring->base);
/* force update visible to other cores */
smp_wmb();
return 0;
}
int mhi_get_free_desc(struct mhi_client_handle *client_handle)
{
u32 chan;
struct mhi_client_config *client_config;
struct mhi_device_ctxt *ctxt;
int bb_ring, ch_ring;
if (!client_handle)
return -EINVAL;
client_config = client_handle->client_config;
ctxt = client_config->mhi_dev_ctxt;
chan = client_config->chan_info.chan_nr;
bb_ring = get_nr_avail_ring_elements(ctxt, &ctxt->chan_bb_list[chan]);
ch_ring = get_nr_avail_ring_elements(ctxt,
&ctxt->mhi_local_chan_ctxt[chan]);
return min(bb_ring, ch_ring);
}
EXPORT_SYMBOL(mhi_get_free_desc);
int get_nr_avail_ring_elements(struct mhi_device_ctxt *mhi_dev_ctxt,
struct mhi_ring *ring)
{
u32 nr_el = 0;
uintptr_t ring_size = 0;
int ret_val = 0;
ring_size = ring->len / ring->el_size;
ret_val = get_nr_enclosed_el(ring, ring->rp, ring->wp, &nr_el);
if (ret_val != 0) {
mhi_log(mhi_dev_ctxt, MHI_MSG_ERROR,
"Failed to get enclosed el ret %d.\n", ret_val);
return 0;
}
return ring_size - nr_el - 1;
}
int get_nr_enclosed_el(struct mhi_ring *ring, void *rp,
void *wp, u32 *nr_el)
{
uintptr_t index_rp = 0;
uintptr_t index_wp = 0;
uintptr_t ring_size = 0;
int r = 0;
if (NULL == ring || 0 == ring->el_size ||
NULL == ring->base || 0 == ring->len) {
return -EINVAL;
}
r = get_element_index(ring, rp, &index_rp);
if (r)
return r;
r = get_element_index(ring, wp, &index_wp);
if (r)
return r;
ring_size = ring->len / ring->el_size;
if (index_rp < index_wp)
*nr_el = index_wp - index_rp;
else if (index_rp > index_wp)
*nr_el = ring_size - (index_rp - index_wp);
else
*nr_el = 0;
return 0;
}
int get_element_index(struct mhi_ring *ring,
void *address, uintptr_t *index)
{
int r = validate_ring_el_addr(ring, (uintptr_t)address);
if (r)
return r;
*index = ((uintptr_t)address - (uintptr_t)ring->base) / ring->el_size;
return r;
}
int get_element_addr(struct mhi_ring *ring,
uintptr_t index, void **address)
{
uintptr_t ring_size = 0;
if (NULL == ring || NULL == address)
return -EINVAL;
ring_size = ring->len / ring->el_size;
*address = (void *)((uintptr_t)ring->base +
(index % ring_size) * ring->el_size);
return 0;
}
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