diff options
Diffstat (limited to 'drivers/bus/mhi/ep/ring.c')
| -rw-r--r-- | drivers/bus/mhi/ep/ring.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/drivers/bus/mhi/ep/ring.c b/drivers/bus/mhi/ep/ring.c new file mode 100644 index 000000000..115518ec7 --- /dev/null +++ b/drivers/bus/mhi/ep/ring.c @@ -0,0 +1,207 @@ +// 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; +} |