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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 
 /* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
  * Copyright (C) 2019-2020 Linaro Ltd.
  */
 
 #include <linux/types.h>
 #include <linux/bits.h>
 #include <linux/bitfield.h>
 #include <linux/refcount.h>
 #include <linux/scatterlist.h>
 #include <linux/dma-direction.h>
 
 #include "gsi.h"
 #include "gsi_private.h"
 #include "gsi_trans.h"
 #include "ipa_gsi.h"
 #include "ipa_data.h"
 #include "ipa_cmd.h"
 
 /**
  * DOC: GSI Transactions
  *
  * A GSI transaction abstracts the behavior of a GSI channel by representing
  * everything about a related group of IPA commands in a single structure.
  * (A "command" in this sense is either a data transfer or an IPA immediate
  * command.)  Most details of interaction with the GSI hardware are managed
  * by the GSI transaction core, allowing users to simply describe commands
  * to be performed.  When a transaction has completed a callback function
  * (dependent on the type of endpoint associated with the channel) allows
  * cleanup of resources associated with the transaction.
  *
  * To perform a command (or set of them), a user of the GSI transaction
  * interface allocates a transaction, indicating the number of TREs required
  * (one per command).  If sufficient TREs are available, they are reserved
  * for use in the transaction and the allocation succeeds.  This way
  * exhaustion of the available TREs in a channel ring is detected
  * as early as possible.  All resources required to complete a transaction
  * are allocated at transaction allocation time.
  *
  * Commands performed as part of a transaction are represented in an array
  * of Linux scatterlist structures.  This array is allocated with the
  * transaction, and its entries are initialized using standard scatterlist
  * functions (such as sg_set_buf() or skb_to_sgvec()).
  *
  * Once a transaction's scatterlist structures have been initialized, the
  * transaction is committed.  The caller is responsible for mapping buffers
  * for DMA if necessary, and this should be done *before* allocating
  * the transaction.  Between a successful allocation and commit of a
  * transaction no errors should occur.
  *
  * Committing transfers ownership of the entire transaction to the GSI
  * transaction core.  The GSI transaction code formats the content of
  * the scatterlist array into the channel ring buffer and informs the
  * hardware that new TREs are available to process.
  *
  * The last TRE in each transaction is marked to interrupt the AP when the
  * GSI hardware has completed it.  Because transfers described by TREs are
  * performed strictly in order, signaling the completion of just the last
  * TRE in the transaction is sufficient to indicate the full transaction
  * is complete.
  *
  * When a transaction is complete, ipa_gsi_trans_complete() is called by the
  * GSI code into the IPA layer, allowing it to perform any final cleanup
  * required before the transaction is freed.
  */
 
 /* Hardware values representing a transfer element type */
 enum gsi_tre_type {
     GSI_RE_XFER = 0x2,
     GSI_RE_IMMD_CMD = 0x3,
 };
 
 /* An entry in a channel ring */
 struct gsi_tre {
     __le64 addr;        /* DMA address */
     __le16 len_opcode;  /* length in bytes or enum IPA_CMD_* */
     __le16 reserved;
     __le32 flags;       /* TRE_FLAGS_* */
 };
 
 /* gsi_tre->flags mask values (in CPU byte order) */
 #define TRE_FLAGS_CHAIN_FMASK   GENMASK(0, 0)
 #define TRE_FLAGS_IEOT_FMASK    GENMASK(9, 9)
 #define TRE_FLAGS_BEI_FMASK GENMASK(10, 10)
 #define TRE_FLAGS_TYPE_FMASK    GENMASK(23, 16)
 
 int gsi_trans_pool_init(struct gsi_trans_pool *pool, size_t size, u32 count,
             u32 max_alloc)
 {
     void *virt;
 
     if (!size)
         return -EINVAL;
     if (count < max_alloc)
         return -EINVAL;
     if (!max_alloc)
         return -EINVAL;
 
     /* By allocating a few extra entries in our pool (one less
      * than the maximum number that will be requested in a
      * single allocation), we can always satisfy requests without
      * ever worrying about straddling the end of the pool array.
      * If there aren't enough entries starting at the free index,
      * we just allocate free entries from the beginning of the pool.
      */
     virt = kcalloc(count + max_alloc - 1, size, GFP_KERNEL);
     if (!virt)
         return -ENOMEM;
 
     pool->base = virt;
     /* If the allocator gave us any extra memory, use it */
     pool->count = ksize(pool->base) / size;
     pool->free = 0;
     pool->max_alloc = max_alloc;
     pool->size = size;
     pool->addr = 0;     /* Only used for DMA pools */
 
     return 0;
 }
 
 void gsi_trans_pool_exit(struct gsi_trans_pool *pool)
 {
     kfree(pool->base);
     memset(pool, 0, sizeof(*pool));
 }
 
 /* Allocate the requested number of (zeroed) entries from the pool */
 /* Home-grown DMA pool.  This way we can preallocate and use the tre_count
  * to guarantee allocations will succeed.  Even though we specify max_alloc
  * (and it can be more than one), we only allow allocation of a single
  * element from a DMA pool.
  */
 int gsi_trans_pool_init_dma(struct device *dev, struct gsi_trans_pool *pool,
                 size_t size, u32 count, u32 max_alloc)
 {
     size_t total_size;
     dma_addr_t addr;
     void *virt;
 
     if (!size)
         return -EINVAL;
     if (count < max_alloc)
         return -EINVAL;
     if (!max_alloc)
         return -EINVAL;
 
     /* Don't let allocations cross a power-of-two boundary */
     size = __roundup_pow_of_two(size);
     total_size = (count + max_alloc - 1) * size;
 
     /* The allocator will give us a power-of-2 number of pages
      * sufficient to satisfy our request.  Round up our requested
      * size to avoid any unused space in the allocation.  This way
      * gsi_trans_pool_exit_dma() can assume the total allocated
      * size is exactly (count * size).
      */
     total_size = get_order(total_size) << PAGE_SHIFT;
 
     virt = dma_alloc_coherent(dev, total_size, &addr, GFP_KERNEL);
     if (!virt)
         return -ENOMEM;
 
     pool->base = virt;
     pool->count = total_size / size;
     pool->free = 0;
     pool->size = size;
     pool->max_alloc = max_alloc;
     pool->addr = addr;
 
     return 0;
 }
 
 void gsi_trans_pool_exit_dma(struct device *dev, struct gsi_trans_pool *pool)
 {
     size_t total_size = pool->count * pool->size;
 
     dma_free_coherent(dev, total_size, pool->base, pool->addr);
     memset(pool, 0, sizeof(*pool));
 }
 
 /* Return the byte offset of the next free entry in the pool */
 static u32 gsi_trans_pool_alloc_common(struct gsi_trans_pool *pool, u32 count)
 {
     u32 offset;
 
     WARN_ON(!count);
     WARN_ON(count > pool->max_alloc);
 
     /* Allocate from beginning if wrap would occur */
     if (count > pool->count - pool->free)
         pool->free = 0;
 
     offset = pool->free * pool->size;
     pool->free += count;
     memset(pool->base + offset, 0, count * pool->size);
 
     return offset;
 }
 
 /* Allocate a contiguous block of zeroed entries from a pool */
 void *gsi_trans_pool_alloc(struct gsi_trans_pool *pool, u32 count)
 {
     return pool->base + gsi_trans_pool_alloc_common(pool, count);
 }
 
 /* Allocate a single zeroed entry from a DMA pool */
 void *gsi_trans_pool_alloc_dma(struct gsi_trans_pool *pool, dma_addr_t *addr)
 {
     u32 offset = gsi_trans_pool_alloc_common(pool, 1);
 
     *addr = pool->addr + offset;
 
     return pool->base + offset;
 }
 
 /* Map a TRE ring entry index to the transaction it is associated with */
 static void gsi_trans_map(struct gsi_trans *trans, u32 index)
 {
     struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
 
     /* The completion event will indicate the last TRE used */
     index += trans->used_count - 1;
 
     /* Note: index *must* be used modulo the ring count here */
     channel->trans_info.map[index % channel->tre_ring.count] = trans;
 }
 
 /* Return the transaction mapped to a given ring entry */
 struct gsi_trans *
 gsi_channel_trans_mapped(struct gsi_channel *channel, u32 index)
 {
     /* Note: index *must* be used modulo the ring count here */
     return channel->trans_info.map[index % channel->tre_ring.count];
 }
 
 /* Return the oldest completed transaction for a channel (or null) */
 struct gsi_trans *gsi_channel_trans_complete(struct gsi_channel *channel)
 {
     return list_first_entry_or_null(&channel->trans_info.complete,
                     struct gsi_trans, links);
 }
 
 /* Move a transaction from the allocated list to the committed list */
 static void gsi_trans_move_committed(struct gsi_trans *trans)
 {
     struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
     struct gsi_trans_info *trans_info = &channel->trans_info;
 
     spin_lock_bh(&trans_info->spinlock);
 
     list_move_tail(&trans->links, &trans_info->committed);
 
     spin_unlock_bh(&trans_info->spinlock);
 }
 
 /* Move transactions from the committed list to the pending list */
 static void gsi_trans_move_pending(struct gsi_trans *trans)
 {
     struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
     struct gsi_trans_info *trans_info = &channel->trans_info;
     struct list_head list;
 
     spin_lock_bh(&trans_info->spinlock);
 
     /* Move this transaction and all predecessors to the pending list */
     list_cut_position(&list, &trans_info->committed, &trans->links);
     list_splice_tail(&list, &trans_info->pending);
 
     spin_unlock_bh(&trans_info->spinlock);
 }
 
 /* Move a transaction and all of its predecessors from the pending list
  * to the completed list.
  */
 void gsi_trans_move_complete(struct gsi_trans *trans)
 {
     struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
     struct gsi_trans_info *trans_info = &channel->trans_info;
     struct list_head list;
 
     spin_lock_bh(&trans_info->spinlock);
 
     /* Move this transaction and all predecessors to completed list */
     list_cut_position(&list, &trans_info->pending, &trans->links);
     list_splice_tail(&list, &trans_info->complete);
 
     spin_unlock_bh(&trans_info->spinlock);
 }
 
 /* Move a transaction from the completed list to the polled list */
 void gsi_trans_move_polled(struct gsi_trans *trans)
 {
     struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
     struct gsi_trans_info *trans_info = &channel->trans_info;
 
     spin_lock_bh(&trans_info->spinlock);
 
     list_move_tail(&trans->links, &trans_info->polled);
 
     spin_unlock_bh(&trans_info->spinlock);
 }
 
 /* Reserve some number of TREs on a channel.  Returns true if successful */
 static bool
 gsi_trans_tre_reserve(struct gsi_trans_info *trans_info, u32 tre_count)
 {
     int avail = atomic_read(&trans_info->tre_avail);
     int new;
 
     do {
         new = avail - (int)tre_count;
         if (unlikely(new < 0))
             return false;
     } while (!atomic_try_cmpxchg(&trans_info->tre_avail, &avail, new));
 
     return true;
 }
 
 /* Release previously-reserved TRE entries to a channel */
 static void
 gsi_trans_tre_release(struct gsi_trans_info *trans_info, u32 tre_count)
 {
     atomic_add(tre_count, &trans_info->tre_avail);
 }
 
 /* Return true if no transactions are allocated, false otherwise */
 bool gsi_channel_trans_idle(struct gsi *gsi, u32 channel_id)
 {
     u32 tre_max = gsi_channel_tre_max(gsi, channel_id);
     struct gsi_trans_info *trans_info;
 
     trans_info = &gsi->channel[channel_id].trans_info;
 
     return atomic_read(&trans_info->tre_avail) == tre_max;
 }
 
 /* Allocate a GSI transaction on a channel */
 struct gsi_trans *gsi_channel_trans_alloc(struct gsi *gsi, u32 channel_id,
                       u32 tre_count,
                       enum dma_data_direction direction)
 {
     struct gsi_channel *channel = &gsi->channel[channel_id];
     struct gsi_trans_info *trans_info;
     struct gsi_trans *trans;
 
     if (WARN_ON(tre_count > channel->trans_tre_max))
         return NULL;
 
     trans_info = &channel->trans_info;
 
     /* We reserve the TREs now, but consume them at commit time.
      * If there aren't enough available, we're done.
      */
     if (!gsi_trans_tre_reserve(trans_info, tre_count))
         return NULL;
 
     /* Allocate and initialize non-zero fields in the transaction */
     trans = gsi_trans_pool_alloc(&trans_info->pool, 1);
     trans->gsi = gsi;
     trans->channel_id = channel_id;
     trans->rsvd_count = tre_count;
     init_completion(&trans->completion);
 
     /* Allocate the scatterlist */
     trans->sgl = gsi_trans_pool_alloc(&trans_info->sg_pool, tre_count);
     sg_init_marker(trans->sgl, tre_count);
 
     trans->direction = direction;
 
     spin_lock_bh(&trans_info->spinlock);
 
     list_add_tail(&trans->links, &trans_info->alloc);
 
     spin_unlock_bh(&trans_info->spinlock);
 
     refcount_set(&trans->refcount, 1);
 
     return trans;
 }
 
 /* Free a previously-allocated transaction */
 void gsi_trans_free(struct gsi_trans *trans)
 {
     refcount_t *refcount = &trans->refcount;
     struct gsi_trans_info *trans_info;
     bool last;
 
     /* We must hold the lock to release the last reference */
     if (refcount_dec_not_one(refcount))
         return;
 
     trans_info = &trans->gsi->channel[trans->channel_id].trans_info;
 
     spin_lock_bh(&trans_info->spinlock);
 
     /* Reference might have been added before we got the lock */
     last = refcount_dec_and_test(refcount);
     if (last)
         list_del(&trans->links);
 
     spin_unlock_bh(&trans_info->spinlock);
 
     if (!last)
         return;
 
     if (trans->used_count)
         ipa_gsi_trans_release(trans);
 
     /* Releasing the reserved TREs implicitly frees the sgl[] and
      * (if present) info[] arrays, plus the transaction itself.
      */
     gsi_trans_tre_release(trans_info, trans->rsvd_count);
 }
 
 /* Add an immediate command to a transaction */
 void gsi_trans_cmd_add(struct gsi_trans *trans, void *buf, u32 size,
                dma_addr_t addr, enum ipa_cmd_opcode opcode)
 {
     u32 which = trans->used_count++;
     struct scatterlist *sg;
 
     WARN_ON(which >= trans->rsvd_count);
 
     /* Commands are quite different from data transfer requests.
      * Their payloads come from a pool whose memory is allocated
      * using dma_alloc_coherent().  We therefore do *not* map them
      * for DMA (unlike what we do for pages and skbs).
      *
      * When a transaction completes, the SGL is normally unmapped.
      * A command transaction has direction DMA_NONE, which tells
      * gsi_trans_complete() to skip the unmapping step.
      *
      * The only things we use directly in a command scatter/gather
      * entry are the DMA address and length.  We still need the SG
      * table flags to be maintained though, so assign a NULL page
      * pointer for that purpose.
      */
     sg = &trans->sgl[which];
     sg_assign_page(sg, NULL);
     sg_dma_address(sg) = addr;
     sg_dma_len(sg) = size;
 
     trans->cmd_opcode[which] = opcode;
 }
 
 /* Add a page transfer to a transaction.  It will fill the only TRE. */
 int gsi_trans_page_add(struct gsi_trans *trans, struct page *page, u32 size,
                u32 offset)
 {
     struct scatterlist *sg = &trans->sgl[0];
     int ret;
 
     if (WARN_ON(trans->rsvd_count != 1))
         return -EINVAL;
     if (WARN_ON(trans->used_count))
         return -EINVAL;
 
     sg_set_page(sg, page, size, offset);
     ret = dma_map_sg(trans->gsi->dev, sg, 1, trans->direction);
     if (!ret)
         return -ENOMEM;
 
     trans->used_count++;    /* Transaction now owns the (DMA mapped) page */
 
     return 0;
 }
 
 /* Add an SKB transfer to a transaction.  No other TREs will be used. */
 int gsi_trans_skb_add(struct gsi_trans *trans, struct sk_buff *skb)
 {
     struct scatterlist *sg = &trans->sgl[0];
     u32 used_count;
     int ret;
 
     if (WARN_ON(trans->rsvd_count != 1))
         return -EINVAL;
     if (WARN_ON(trans->used_count))
         return -EINVAL;
 
     /* skb->len will not be 0 (checked early) */
     ret = skb_to_sgvec(skb, sg, 0, skb->len);
     if (ret < 0)
         return ret;
     used_count = ret;
 
     ret = dma_map_sg(trans->gsi->dev, sg, used_count, trans->direction);
     if (!ret)
         return -ENOMEM;
 
     /* Transaction now owns the (DMA mapped) skb */
     trans->used_count += used_count;
 
     return 0;
 }
 
 /* Compute the length/opcode value to use for a TRE */
 static __le16 gsi_tre_len_opcode(enum ipa_cmd_opcode opcode, u32 len)
 {
     return opcode == IPA_CMD_NONE ? cpu_to_le16((u16)len)
                       : cpu_to_le16((u16)opcode);
 }
 
 /* Compute the flags value to use for a given TRE */
 static __le32 gsi_tre_flags(bool last_tre, bool bei, enum ipa_cmd_opcode opcode)
 {
     enum gsi_tre_type tre_type;
     u32 tre_flags;
 
     tre_type = opcode == IPA_CMD_NONE ? GSI_RE_XFER : GSI_RE_IMMD_CMD;
     tre_flags = u32_encode_bits(tre_type, TRE_FLAGS_TYPE_FMASK);
 
     /* Last TRE contains interrupt flags */
     if (last_tre) {
         /* All transactions end in a transfer completion interrupt */
         tre_flags |= TRE_FLAGS_IEOT_FMASK;
         /* Don't interrupt when outbound commands are acknowledged */
         if (bei)
             tre_flags |= TRE_FLAGS_BEI_FMASK;
     } else {    /* All others indicate there's more to come */
         tre_flags |= TRE_FLAGS_CHAIN_FMASK;
     }
 
     return cpu_to_le32(tre_flags);
 }
 
 static void gsi_trans_tre_fill(struct gsi_tre *dest_tre, dma_addr_t addr,
                    u32 len, bool last_tre, bool bei,
                    enum ipa_cmd_opcode opcode)
 {
     struct gsi_tre tre;
 
     tre.addr = cpu_to_le64(addr);
     tre.len_opcode = gsi_tre_len_opcode(opcode, len);
     tre.reserved = 0;
     tre.flags = gsi_tre_flags(last_tre, bei, opcode);
 
     /* ARM64 can write 16 bytes as a unit with a single instruction.
      * Doing the assignment this way is an attempt to make that happen.
      */
     *dest_tre = tre;
 }
 
 /**
  * __gsi_trans_commit() - Common GSI transaction commit code
  * @trans:  Transaction to commit
  * @ring_db:    Whether to tell the hardware about these queued transfers
  *
  * Formats channel ring TRE entries based on the content of the scatterlist.
  * Maps a transaction pointer to the last ring entry used for the transaction,
  * so it can be recovered when it completes.  Moves the transaction to the
  * pending list.  Finally, updates the channel ring pointer and optionally
  * rings the doorbell.
  */
 static void __gsi_trans_commit(struct gsi_trans *trans, bool ring_db)
 {
     struct gsi_channel *channel = &trans->gsi->channel[trans->channel_id];
     struct gsi_ring *tre_ring = &channel->tre_ring;
     enum ipa_cmd_opcode opcode = IPA_CMD_NONE;
     bool bei = channel->toward_ipa;
     struct gsi_tre *dest_tre;
     struct scatterlist *sg;
     u32 byte_count = 0;
     u8 *cmd_opcode;
     u32 avail;
     u32 i;
 
     WARN_ON(!trans->used_count);
 
     /* Consume the entries.  If we cross the end of the ring while
      * filling them we'll switch to the beginning to finish.
      * If there is no info array we're doing a simple data
      * transfer request, whose opcode is IPA_CMD_NONE.
      */
     cmd_opcode = channel->command ? &trans->cmd_opcode[0] : NULL;
     avail = tre_ring->count - tre_ring->index % tre_ring->count;
     dest_tre = gsi_ring_virt(tre_ring, tre_ring->index);
     for_each_sg(trans->sgl, sg, trans->used_count, i) {
         bool last_tre = i == trans->used_count - 1;
         dma_addr_t addr = sg_dma_address(sg);
         u32 len = sg_dma_len(sg);
 
         byte_count += len;
         if (!avail--)
             dest_tre = gsi_ring_virt(tre_ring, 0);
         if (cmd_opcode)
             opcode = *cmd_opcode++;
 
         gsi_trans_tre_fill(dest_tre, addr, len, last_tre, bei, opcode);
         dest_tre++;
     }
     /* Associate the TRE with the transaction */
     gsi_trans_map(trans, tre_ring->index);
 
     tre_ring->index += trans->used_count;
 
     trans->len = byte_count;
     if (channel->toward_ipa)
         gsi_trans_tx_committed(trans);
 
     gsi_trans_move_committed(trans);
 
     /* Ring doorbell if requested, or if all TREs are allocated */
     if (ring_db || !atomic_read(&channel->trans_info.tre_avail)) {
         /* Report what we're handing off to hardware for TX channels */
         if (channel->toward_ipa)
             gsi_trans_tx_queued(trans);
         gsi_trans_move_pending(trans);
         gsi_channel_doorbell(channel);
     }
 }
 
 /* Commit a GSI transaction */
 void gsi_trans_commit(struct gsi_trans *trans, bool ring_db)
 {
     if (trans->used_count)
         __gsi_trans_commit(trans, ring_db);
     else
         gsi_trans_free(trans);
 }
 
 /* Commit a GSI transaction and wait for it to complete */
 void gsi_trans_commit_wait(struct gsi_trans *trans)
 {
     if (!trans->used_count)
         goto out_trans_free;
 
     refcount_inc(&trans->refcount);
 
     __gsi_trans_commit(trans, true);
 
     wait_for_completion(&trans->completion);
 
 out_trans_free:
     gsi_trans_free(trans);
 }
 
 /* Process the completion of a transaction; called while polling */
 void gsi_trans_complete(struct gsi_trans *trans)
 {
     /* If the entire SGL was mapped when added, unmap it now */
     if (trans->direction != DMA_NONE)
         dma_unmap_sg(trans->gsi->dev, trans->sgl, trans->used_count,
                  trans->direction);
 
     ipa_gsi_trans_complete(trans);
 
     complete(&trans->completion);
 
     gsi_trans_free(trans);
 }
 
 /* Cancel a channel's pending transactions */
 void gsi_channel_trans_cancel_pending(struct gsi_channel *channel)
 {
     struct gsi_trans_info *trans_info = &channel->trans_info;
     struct gsi_trans *trans;
     bool cancelled;
 
     /* channel->gsi->mutex is held by caller */
     spin_lock_bh(&trans_info->spinlock);
 
     cancelled = !list_empty(&trans_info->pending);
     list_for_each_entry(trans, &trans_info->pending, links)
         trans->cancelled = true;
 
     list_splice_tail_init(&trans_info->pending, &trans_info->complete);
 
     spin_unlock_bh(&trans_info->spinlock);
 
     /* Schedule NAPI polling to complete the cancelled transactions */
     if (cancelled)
         napi_schedule(&channel->napi);
 }
 
 /* Issue a command to read a single byte from a channel */
 int gsi_trans_read_byte(struct gsi *gsi, u32 channel_id, dma_addr_t addr)
 {
     struct gsi_channel *channel = &gsi->channel[channel_id];
     struct gsi_ring *tre_ring = &channel->tre_ring;
     struct gsi_trans_info *trans_info;
     struct gsi_tre *dest_tre;
 
     trans_info = &channel->trans_info;
 
     /* First reserve the TRE, if possible */
     if (!gsi_trans_tre_reserve(trans_info, 1))
         return -EBUSY;
 
     /* Now fill the reserved TRE and tell the hardware */
 
     dest_tre = gsi_ring_virt(tre_ring, tre_ring->index);
     gsi_trans_tre_fill(dest_tre, addr, 1, true, false, IPA_CMD_NONE);
 
     tre_ring->index++;
     gsi_channel_doorbell(channel);
 
     return 0;
 }
 
 /* Mark a gsi_trans_read_byte() request done */
 void gsi_trans_read_byte_done(struct gsi *gsi, u32 channel_id)
 {
     struct gsi_channel *channel = &gsi->channel[channel_id];
 
     gsi_trans_tre_release(&channel->trans_info, 1);
 }
 
 /* Initialize a channel's GSI transaction info */
 int gsi_channel_trans_init(struct gsi *gsi, u32 channel_id)
 {
     struct gsi_channel *channel = &gsi->channel[channel_id];
     u32 tre_count = channel->tre_count;
     struct gsi_trans_info *trans_info;
     u32 tre_max;
     int ret;
 
     /* Ensure the size of a channel element is what's expected */
     BUILD_BUG_ON(sizeof(struct gsi_tre) != GSI_RING_ELEMENT_SIZE);
 
     trans_info = &channel->trans_info;
 
     /* The tre_avail field is what ultimately limits the number of
      * outstanding transactions and their resources.  A transaction
      * allocation succeeds only if the TREs available are sufficient
      * for what the transaction might need.
      */
     tre_max = gsi_channel_tre_max(channel->gsi, channel_id);
     atomic_set(&trans_info->tre_avail, tre_max);
 
     /* We can't use more TREs than the number available in the ring.
      * This limits the number of transactions that can be outstanding.
      * Worst case is one TRE per transaction (but we actually limit
      * it to something a little less than that).  By allocating a
      * power-of-two number of transactions we can use an index
      * modulo that number to determine the next one that's free.
      * Transactions are allocated one at a time.
      */
     ret = gsi_trans_pool_init(&trans_info->pool, sizeof(struct gsi_trans),
                   tre_max, 1);
     if (ret)
         return -ENOMEM;
 
     /* A completion event contains a pointer to the TRE that caused
      * the event (which will be the last one used by the transaction).
      * Each entry in this map records the transaction associated
      * with a corresponding completed TRE.
      */
     trans_info->map = kcalloc(tre_count, sizeof(*trans_info->map),
                   GFP_KERNEL);
     if (!trans_info->map) {
         ret = -ENOMEM;
         goto err_trans_free;
     }
 
     /* A transaction uses a scatterlist array to represent the data
      * transfers implemented by the transaction.  Each scatterlist
      * element is used to fill a single TRE when the transaction is
      * committed.  So we need as many scatterlist elements as the
      * maximum number of TREs that can be outstanding.
      */
     ret = gsi_trans_pool_init(&trans_info->sg_pool,
                   sizeof(struct scatterlist),
                   tre_max, channel->trans_tre_max);
     if (ret)
         goto err_map_free;
 
     spin_lock_init(&trans_info->spinlock);
     INIT_LIST_HEAD(&trans_info->alloc);
     INIT_LIST_HEAD(&trans_info->committed);
     INIT_LIST_HEAD(&trans_info->pending);
     INIT_LIST_HEAD(&trans_info->complete);
     INIT_LIST_HEAD(&trans_info->polled);
 
     return 0;
 
 err_map_free:
     kfree(trans_info->map);
 err_trans_free:
     gsi_trans_pool_exit(&trans_info->pool);
 
     dev_err(gsi->dev, "error %d initializing channel %u transactions\n",
         ret, channel_id);
 
     return ret;
 }
 
 /* Inverse of gsi_channel_trans_init() */
 void gsi_channel_trans_exit(struct gsi_channel *channel)
 {
     struct gsi_trans_info *trans_info = &channel->trans_info;
 
     gsi_trans_pool_exit(&trans_info->sg_pool);
     gsi_trans_pool_exit(&trans_info->pool);
     kfree(trans_info->map);
 }

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