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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2022 Linaro Ltd.
* Author: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
*/
#include <linux/mhi_ep.h>
#include "internal.h"
size_t mhi_ep_ring_addr2offset(struct mhi_ep_ring *ring, u64 ptr)
{
return (ptr - ring->rbase) / sizeof(struct mhi_ring_element);
}
static u32 mhi_ep_ring_num_elems(struct mhi_ep_ring *ring)
{
__le64 rlen;
memcpy_fromio(&rlen, (void __iomem *) &ring->ring_ctx->generic.rlen, sizeof(u64));
return le64_to_cpu(rlen) / sizeof(struct mhi_ring_element);
}
void mhi_ep_ring_inc_index(struct mhi_ep_ring *ring)
{
ring->rd_offset = (ring->rd_offset + 1) % ring->ring_size;
}
static int __mhi_ep_cache_ring(struct mhi_ep_ring *ring, size_t end)
{
struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
struct device *dev = &mhi_cntrl->mhi_dev->dev;
size_t start, copy_size;
int ret;
/* Don't proceed in the case of event ring. This happens during mhi_ep_ring_start(). */
if (ring->type == RING_TYPE_ER)
return 0;
/* No need to cache the ring if write pointer is unmodified */
if (ring->wr_offset == end)
return 0;
start = ring->wr_offset;
if (start < end) {
copy_size = (end - start) * sizeof(struct mhi_ring_element);
ret = mhi_cntrl->read_from_host(mhi_cntrl, ring->rbase +
(start * sizeof(struct mhi_ring_element)),
&ring->ring_cache[start], copy_size);
if (ret < 0)
return ret;
} else {
copy_size = (ring->ring_size - start) * sizeof(struct mhi_ring_element);
ret = mhi_cntrl->read_from_host(mhi_cntrl, ring->rbase +
(start * sizeof(struct mhi_ring_element)),
&ring->ring_cache[start], copy_size);
if (ret < 0)
return ret;
if (end) {
ret = mhi_cntrl->read_from_host(mhi_cntrl, ring->rbase,
&ring->ring_cache[0],
end * sizeof(struct mhi_ring_element));
if (ret < 0)
return ret;
}
}
dev_dbg(dev, "Cached ring: start %zu end %zu size %zu\n", start, end, copy_size);
return 0;
}
static int mhi_ep_cache_ring(struct mhi_ep_ring *ring, u64 wr_ptr)
{
size_t wr_offset;
int ret;
wr_offset = mhi_ep_ring_addr2offset(ring, wr_ptr);
/* Cache the host ring till write offset */
ret = __mhi_ep_cache_ring(ring, wr_offset);
if (ret)
return ret;
ring->wr_offset = wr_offset;
return 0;
}
int mhi_ep_update_wr_offset(struct mhi_ep_ring *ring)
{
u64 wr_ptr;
wr_ptr = mhi_ep_mmio_get_db(ring);
return mhi_ep_cache_ring(ring, wr_ptr);
}
/* TODO: Support for adding multiple ring elements to the ring */
int mhi_ep_ring_add_element(struct mhi_ep_ring *ring, struct mhi_ring_element *el)
{
struct mhi_ep_cntrl *mhi_cntrl = ring->mhi_cntrl;
struct device *dev = &mhi_cntrl->mhi_dev->dev;
size_t old_offset = 0;
u32 num_free_elem;
__le64 rp;
int ret;
ret = mhi_ep_update_wr_offset(ring);
if (ret) {
dev_err(dev, "Error updating write pointer\n");
return ret;
}
if (ring->rd_offset < ring->wr_offset)
num_free_elem = (ring->wr_offset - ring->rd_offset) - 1;
else
num_free_elem = ((ring->ring_size - ring->rd_offset) + ring->wr_offset) - 1;
/* Check if there is space in ring for adding at least an element */
if (!num_free_elem) {
dev_err(dev, "No space left in the ring\n");
return -ENOSPC;
}
old_offset = ring->rd_offset;
mhi_ep_ring_inc_index(ring);
dev_dbg(dev, "Adding an element to ring at offset (%zu)\n", ring->rd_offset);
/* Update rp in ring context */
rp = cpu_to_le64(ring->rd_offset * sizeof(*el) + ring->rbase);
memcpy_toio((void __iomem *) &ring->ring_ctx->generic.rp, &rp, sizeof(u64));
ret = mhi_cntrl->write_to_host(mhi_cntrl, el, ring->rbase + (old_offset * sizeof(*el)),
sizeof(*el));
if (ret < 0)
return ret;
return 0;
}
void mhi_ep_ring_init(struct mhi_ep_ring *ring, enum mhi_ep_ring_type type, u32 id)
{
ring->type = type;
if (ring->type == RING_TYPE_CMD) {
ring->db_offset_h = EP_CRDB_HIGHER;
ring->db_offset_l = EP_CRDB_LOWER;
} else if (ring->type == RING_TYPE_CH) {
ring->db_offset_h = CHDB_HIGHER_n(id);
ring->db_offset_l = CHDB_LOWER_n(id);
ring->ch_id = id;
} else {
ring->db_offset_h = ERDB_HIGHER_n(id);
ring->db_offset_l = ERDB_LOWER_n(id);
}
}
int mhi_ep_ring_start(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring,
union mhi_ep_ring_ctx *ctx)
{
struct device *dev = &mhi_cntrl->mhi_dev->dev;
__le64 val;
int ret;
ring->mhi_cntrl = mhi_cntrl;
ring->ring_ctx = ctx;
ring->ring_size = mhi_ep_ring_num_elems(ring);
memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.rbase, sizeof(u64));
ring->rbase = le64_to_cpu(val);
if (ring->type == RING_TYPE_CH)
ring->er_index = le32_to_cpu(ring->ring_ctx->ch.erindex);
if (ring->type == RING_TYPE_ER)
ring->irq_vector = le32_to_cpu(ring->ring_ctx->ev.msivec);
/* During ring init, both rp and wp are equal */
memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.rp, sizeof(u64));
ring->rd_offset = mhi_ep_ring_addr2offset(ring, le64_to_cpu(val));
ring->wr_offset = mhi_ep_ring_addr2offset(ring, le64_to_cpu(val));
/* Allocate ring cache memory for holding the copy of host ring */
ring->ring_cache = kcalloc(ring->ring_size, sizeof(struct mhi_ring_element), GFP_KERNEL);
if (!ring->ring_cache)
return -ENOMEM;
memcpy_fromio(&val, (void __iomem *) &ring->ring_ctx->generic.wp, sizeof(u64));
ret = mhi_ep_cache_ring(ring, le64_to_cpu(val));
if (ret) {
dev_err(dev, "Failed to cache ring\n");
kfree(ring->ring_cache);
return ret;
}
ring->started = true;
return 0;
}
void mhi_ep_ring_reset(struct mhi_ep_cntrl *mhi_cntrl, struct mhi_ep_ring *ring)
{
ring->started = false;
kfree(ring->ring_cache);
ring->ring_cache = NULL;
}
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