// SPDX-License-Identifier: GPL-2.0

/* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
 * Copyright (C) 2019-2021 Linaro Ltd.
 */

#include <linux/types.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/bitfield.h>
#include <linux/dma-direction.h>

#include "gsi.h"
#include "gsi_trans.h"
#include "ipa.h"
#include "ipa_endpoint.h"
#include "ipa_table.h"
#include "ipa_cmd.h"
#include "ipa_mem.h"

/**
 * DOC:  IPA Immediate Commands
 *
 * The AP command TX endpoint is used to issue immediate commands to the IPA.
 * An immediate command is generally used to request the IPA do something
 * other than data transfer to another endpoint.
 *
 * Immediate commands are represented by GSI transactions just like other
 * transfer requests, represented by a single GSI TRE.  Each immediate
 * command has a well-defined format, having a payload of a known length.
 * This allows the transfer element's length field to be used to hold an
 * immediate command's opcode.  The payload for a command resides in DRAM
 * and is described by a single scatterlist entry in its transaction.
 * Commands do not require a transaction completion callback.  To commit
 * an immediate command transaction, either gsi_trans_commit_wait() or
 * gsi_trans_commit_wait_timeout() is used.
 */

/* Some commands can wait until indicated pipeline stages are clear */
enum pipeline_clear_options {
        pipeline_clear_hps              = 0x0,
        pipeline_clear_src_grp          = 0x1,
        pipeline_clear_full             = 0x2,
};

/* IPA_CMD_IP_V{4,6}_{FILTER,ROUTING}_INIT */

struct ipa_cmd_hw_ip_fltrt_init {
        __le64 hash_rules_addr;
        __le64 flags;
        __le64 nhash_rules_addr;
};

/* Field masks for ipa_cmd_hw_ip_fltrt_init structure fields */
#define IP_FLTRT_FLAGS_HASH_SIZE_FMASK                  GENMASK_ULL(11, 0)
#define IP_FLTRT_FLAGS_HASH_ADDR_FMASK                  GENMASK_ULL(27, 12)
#define IP_FLTRT_FLAGS_NHASH_SIZE_FMASK                 GENMASK_ULL(39, 28)
#define IP_FLTRT_FLAGS_NHASH_ADDR_FMASK                 GENMASK_ULL(55, 40)

/* IPA_CMD_HDR_INIT_LOCAL */

struct ipa_cmd_hw_hdr_init_local {
        __le64 hdr_table_addr;
        __le32 flags;
        __le32 reserved;
};

/* Field masks for ipa_cmd_hw_hdr_init_local structure fields */
#define HDR_INIT_LOCAL_FLAGS_TABLE_SIZE_FMASK           GENMASK(11, 0)
#define HDR_INIT_LOCAL_FLAGS_HDR_ADDR_FMASK             GENMASK(27, 12)

/* IPA_CMD_REGISTER_WRITE */

/* For IPA v4.0+, the pipeline clear options are encoded in the opcode */
#define REGISTER_WRITE_OPCODE_SKIP_CLEAR_FMASK          GENMASK(8, 8)
#define REGISTER_WRITE_OPCODE_CLEAR_OPTION_FMASK        GENMASK(10, 9)

struct ipa_cmd_register_write {
        __le16 flags;           /* Unused/reserved prior to IPA v4.0 */
        __le16 offset;
        __le32 value;
        __le32 value_mask;
        __le32 clear_options;   /* Unused/reserved for IPA v4.0+ */
};

/* Field masks for ipa_cmd_register_write structure fields */
/* The next field is present for IPA v4.0+ */
#define REGISTER_WRITE_FLAGS_OFFSET_HIGH_FMASK          GENMASK(14, 11)
/* The next field is not present for IPA v4.0+ */
#define REGISTER_WRITE_FLAGS_SKIP_CLEAR_FMASK           GENMASK(15, 15)

/* The next field and its values are not present for IPA v4.0+ */
#define REGISTER_WRITE_CLEAR_OPTIONS_FMASK              GENMASK(1, 0)

/* IPA_CMD_IP_PACKET_INIT */

struct ipa_cmd_ip_packet_init {
        u8 dest_endpoint;
        u8 reserved[7];
};

/* Field masks for ipa_cmd_ip_packet_init dest_endpoint field */
#define IPA_PACKET_INIT_DEST_ENDPOINT_FMASK             GENMASK(4, 0)

/* IPA_CMD_DMA_SHARED_MEM */

/* For IPA v4.0+, this opcode gets modified with pipeline clear options */

#define DMA_SHARED_MEM_OPCODE_SKIP_CLEAR_FMASK          GENMASK(8, 8)
#define DMA_SHARED_MEM_OPCODE_CLEAR_OPTION_FMASK        GENMASK(10, 9)

struct ipa_cmd_hw_dma_mem_mem {
        __le16 clear_after_read; /* 0 or DMA_SHARED_MEM_CLEAR_AFTER_READ */
        __le16 size;
        __le16 local_addr;
        __le16 flags;
        __le64 system_addr;
};

/* Flag allowing atomic clear of target region after reading data (v4.0+)*/
#define DMA_SHARED_MEM_CLEAR_AFTER_READ                 GENMASK(15, 15)

/* Field masks for ipa_cmd_hw_dma_mem_mem structure fields */
#define DMA_SHARED_MEM_FLAGS_DIRECTION_FMASK            GENMASK(0, 0)
/* The next two fields are not present for IPA v4.0+ */
#define DMA_SHARED_MEM_FLAGS_SKIP_CLEAR_FMASK           GENMASK(1, 1)
#define DMA_SHARED_MEM_FLAGS_CLEAR_OPTIONS_FMASK        GENMASK(3, 2)

/* IPA_CMD_IP_PACKET_TAG_STATUS */

struct ipa_cmd_ip_packet_tag_status {
        __le64 tag;
};

#define IP_PACKET_TAG_STATUS_TAG_FMASK                  GENMASK_ULL(63, 16)

/* Immediate command payload */
union ipa_cmd_payload {
        struct ipa_cmd_hw_ip_fltrt_init table_init;
        struct ipa_cmd_hw_hdr_init_local hdr_init_local;
        struct ipa_cmd_register_write register_write;
        struct ipa_cmd_ip_packet_init ip_packet_init;
        struct ipa_cmd_hw_dma_mem_mem dma_shared_mem;
        struct ipa_cmd_ip_packet_tag_status ip_packet_tag_status;
};

static void ipa_cmd_validate_build(void)
{
        /* The sizes of a filter and route tables need to fit into fields
         * in the ipa_cmd_hw_ip_fltrt_init structure.  Although hashed tables
         * might not be used, non-hashed and hashed tables have the same
         * maximum size.  IPv4 and IPv6 filter tables have the same number
         * of entries, as and IPv4 and IPv6 route tables have the same number
         * of entries.
         */
#define TABLE_SIZE      (TABLE_COUNT_MAX * sizeof(__le64))
#define TABLE_COUNT_MAX max_t(u32, IPA_ROUTE_COUNT_MAX, IPA_FILTER_COUNT_MAX)
        BUILD_BUG_ON(TABLE_SIZE > field_max(IP_FLTRT_FLAGS_HASH_SIZE_FMASK));
        BUILD_BUG_ON(TABLE_SIZE > field_max(IP_FLTRT_FLAGS_NHASH_SIZE_FMASK));
#undef TABLE_COUNT_MAX
#undef TABLE_SIZE
}

#ifdef IPA_VALIDATE

/* Validate a memory region holding a table */
bool ipa_cmd_table_valid(struct ipa *ipa, const struct ipa_mem *mem,
                         bool route, bool ipv6, bool hashed)
{
        struct device *dev = &ipa->pdev->dev;
        u32 offset_max;

        offset_max = hashed ? field_max(IP_FLTRT_FLAGS_HASH_ADDR_FMASK)
                            : field_max(IP_FLTRT_FLAGS_NHASH_ADDR_FMASK);
        if (mem->offset > offset_max ||
            ipa->mem_offset > offset_max - mem->offset) {
                dev_err(dev, "IPv%c %s%s table region offset too large\n",
                        ipv6 ? '6' : '4', hashed ? "hashed " : "",
                        route ? "route" : "filter");
                dev_err(dev, "    (0x%04x + 0x%04x > 0x%04x)\n",
                        ipa->mem_offset, mem->offset, offset_max);

                return false;
        }

        if (mem->offset > ipa->mem_size ||
            mem->size > ipa->mem_size - mem->offset) {
                dev_err(dev, "IPv%c %s%s table region out of range\n",
                        ipv6 ? '6' : '4', hashed ? "hashed " : "",
                        route ? "route" : "filter");
                dev_err(dev, "    (0x%04x + 0x%04x > 0x%04x)\n",
                        mem->offset, mem->size, ipa->mem_size);

                return false;
        }

        return true;
}

/* Validate the memory region that holds headers */
static bool ipa_cmd_header_valid(struct ipa *ipa)
{
        const struct ipa_mem *mem = &ipa->mem[IPA_MEM_MODEM_HEADER];
        struct device *dev = &ipa->pdev->dev;
        u32 offset_max;
        u32 size_max;
        u32 size;

        /* In ipa_cmd_hdr_init_local_add() we record the offset and size
         * of the header table memory area.  Make sure the offset and size
         * fit in the fields that need to hold them, and that the entire
         * range is within the overall IPA memory range.
         */
        offset_max = field_max(HDR_INIT_LOCAL_FLAGS_HDR_ADDR_FMASK);
        if (mem->offset > offset_max ||
            ipa->mem_offset > offset_max - mem->offset) {
                dev_err(dev, "header table region offset too large\n");
                dev_err(dev, "    (0x%04x + 0x%04x > 0x%04x)\n",
                        ipa->mem_offset, mem->offset, offset_max);

                return false;
        }

        size_max = field_max(HDR_INIT_LOCAL_FLAGS_TABLE_SIZE_FMASK);
        size = ipa->mem[IPA_MEM_MODEM_HEADER].size;
        size += ipa->mem[IPA_MEM_AP_HEADER].size;

        if (size > size_max) {
                dev_err(dev, "header table region size too large\n");
                dev_err(dev, "    (0x%04x > 0x%08x)\n", size, size_max);

                return false;
        }
        if (size > ipa->mem_size || mem->offset > ipa->mem_size - size) {
                dev_err(dev, "header table region out of range\n");
                dev_err(dev, "    (0x%04x + 0x%04x > 0x%04x)\n",
                        mem->offset, size, ipa->mem_size);

                return false;
        }

        return true;
}

/* Indicate whether an offset can be used with a register_write command */
static bool ipa_cmd_register_write_offset_valid(struct ipa *ipa,
                                                const char *name, u32 offset)
{
        struct ipa_cmd_register_write *payload;
        struct device *dev = &ipa->pdev->dev;
        u32 offset_max;
        u32 bit_count;

        /* The maximum offset in a register_write immediate command depends
         * on the version of IPA.  A 16 bit offset is always supported,
         * but starting with IPA v4.0 some additional high-order bits are
         * allowed.
         */
        bit_count = BITS_PER_BYTE * sizeof(payload->offset);
        if (ipa->version >= IPA_VERSION_4_0)
                bit_count += hweight32(REGISTER_WRITE_FLAGS_OFFSET_HIGH_FMASK);
        BUILD_BUG_ON(bit_count > 32);
        offset_max = ~0U >> (32 - bit_count);

        /* Make sure the offset can be represented by the field(s)
         * that holds it.  Also make sure the offset is not outside
         * the overall IPA memory range.
         */
        if (offset > offset_max || ipa->mem_offset > offset_max - offset) {
                dev_err(dev, "%s offset too large 0x%04x + 0x%04x > 0x%04x)\n",
                        name, ipa->mem_offset, offset, offset_max);
                return false;
        }

        return true;
}

/* Check whether offsets passed to register_write are valid */
static bool ipa_cmd_register_write_valid(struct ipa *ipa)
{
        const char *name;
        u32 offset;

        /* If hashed tables are supported, ensure the hash flush register
         * offset will fit in a register write IPA immediate command.
         */
        if (ipa_table_hash_support(ipa)) {
                offset = ipa_reg_filt_rout_hash_flush_offset(ipa->version);
                name = "filter/route hash flush";
                if (!ipa_cmd_register_write_offset_valid(ipa, name, offset))
                        return false;
        }

        /* Each endpoint can have a status endpoint associated with it,
         * and this is recorded in an endpoint register.  If the modem
         * crashes, we reset the status endpoint for all modem endpoints
         * using a register write IPA immediate command.  Make sure the
         * worst case (highest endpoint number) offset of that endpoint
         * fits in the register write command field(s) that must hold it.
         */
        offset = IPA_REG_ENDP_STATUS_N_OFFSET(IPA_ENDPOINT_COUNT - 1);
        name = "maximal endpoint status";
        if (!ipa_cmd_register_write_offset_valid(ipa, name, offset))
                return false;

        return true;
}

bool ipa_cmd_data_valid(struct ipa *ipa)
{
        if (!ipa_cmd_header_valid(ipa))
                return false;

        if (!ipa_cmd_register_write_valid(ipa))
                return false;

        return true;
}

#endif /* IPA_VALIDATE */

int ipa_cmd_pool_init(struct gsi_channel *channel, u32 tre_max)
{
        struct gsi_trans_info *trans_info = &channel->trans_info;
        struct device *dev = channel->gsi->dev;
        int ret;

        /* This is as good a place as any to validate build constants */
        ipa_cmd_validate_build();

        /* Even though command payloads are allocated one at a time,
         * a single transaction can require up to tlv_count of them,
         * so we treat them as if that many can be allocated at once.
         */
        ret = gsi_trans_pool_init_dma(dev, &trans_info->cmd_pool,
                                      sizeof(union ipa_cmd_payload),
                                      tre_max, channel->tlv_count);
        if (ret)
                return ret;

        /* Each TRE needs a command info structure */
        ret = gsi_trans_pool_init(&trans_info->info_pool,
                                   sizeof(struct ipa_cmd_info),
                                   tre_max, channel->tlv_count);
        if (ret)
                gsi_trans_pool_exit_dma(dev, &trans_info->cmd_pool);

        return ret;
}

void ipa_cmd_pool_exit(struct gsi_channel *channel)
{
        struct gsi_trans_info *trans_info = &channel->trans_info;
        struct device *dev = channel->gsi->dev;

        gsi_trans_pool_exit(&trans_info->info_pool);
        gsi_trans_pool_exit_dma(dev, &trans_info->cmd_pool);
}

static union ipa_cmd_payload *
ipa_cmd_payload_alloc(struct ipa *ipa, dma_addr_t *addr)
{
        struct gsi_trans_info *trans_info;
        struct ipa_endpoint *endpoint;

        endpoint = ipa->name_map[IPA_ENDPOINT_AP_COMMAND_TX];
        trans_info = &ipa->gsi.channel[endpoint->channel_id].trans_info;

        return gsi_trans_pool_alloc_dma(&trans_info->cmd_pool, addr);
}

/* If hash_size is 0, hash_offset and hash_addr ignored. */
void ipa_cmd_table_init_add(struct gsi_trans *trans,
                            enum ipa_cmd_opcode opcode, u16 size, u32 offset,
                            dma_addr_t addr, u16 hash_size, u32 hash_offset,
                            dma_addr_t hash_addr)
{
        struct ipa *ipa = container_of(trans->gsi, struct ipa, gsi);
        enum dma_data_direction direction = DMA_TO_DEVICE;
        struct ipa_cmd_hw_ip_fltrt_init *payload;
        union ipa_cmd_payload *cmd_payload;
        dma_addr_t payload_addr;
        u64 val;

        /* Record the non-hash table offset and size */
        offset += ipa->mem_offset;
        val = u64_encode_bits(offset, IP_FLTRT_FLAGS_NHASH_ADDR_FMASK);
        val |= u64_encode_bits(size, IP_FLTRT_FLAGS_NHASH_SIZE_FMASK);

        /* The hash table offset and address are zero if its size is 0 */
        if (hash_size) {
                /* Record the hash table offset and size */
                hash_offset += ipa->mem_offset;
                val |= u64_encode_bits(hash_offset,
                                       IP_FLTRT_FLAGS_HASH_ADDR_FMASK);
                val |= u64_encode_bits(hash_size,
                                       IP_FLTRT_FLAGS_HASH_SIZE_FMASK);
        }

        cmd_payload = ipa_cmd_payload_alloc(ipa, &payload_addr);
        payload = &cmd_payload->table_init;

        /* Fill in all offsets and sizes and the non-hash table address */
        if (hash_size)
                payload->hash_rules_addr = cpu_to_le64(hash_addr);
        payload->flags = cpu_to_le64(val);
        payload->nhash_rules_addr = cpu_to_le64(addr);

        gsi_trans_cmd_add(trans, payload, sizeof(*payload), payload_addr,
                          direction, opcode);
}

/* Initialize header space in IPA-local memory */
void ipa_cmd_hdr_init_local_add(struct gsi_trans *trans, u32 offset, u16 size,
                                dma_addr_t addr)
{
        struct ipa *ipa = container_of(trans->gsi, struct ipa, gsi);
        enum ipa_cmd_opcode opcode = IPA_CMD_HDR_INIT_LOCAL;
        enum dma_data_direction direction = DMA_TO_DEVICE;
        struct ipa_cmd_hw_hdr_init_local *payload;
        union ipa_cmd_payload *cmd_payload;
        dma_addr_t payload_addr;
        u32 flags;

        offset += ipa->mem_offset;

        /* With this command we tell the IPA where in its local memory the
         * header tables reside.  The content of the buffer provided is
         * also written via DMA into that space.  The IPA hardware owns
         * the table, but the AP must initialize it.
         */
        cmd_payload = ipa_cmd_payload_alloc(ipa, &payload_addr);
        payload = &cmd_payload->hdr_init_local;

        payload->hdr_table_addr = cpu_to_le64(addr);
        flags = u32_encode_bits(size, HDR_INIT_LOCAL_FLAGS_TABLE_SIZE_FMASK);
        flags |= u32_encode_bits(offset, HDR_INIT_LOCAL_FLAGS_HDR_ADDR_FMASK);
        payload->flags = cpu_to_le32(flags);

        gsi_trans_cmd_add(trans, payload, sizeof(*payload), payload_addr,
                          direction, opcode);
}

void ipa_cmd_register_write_add(struct gsi_trans *trans, u32 offset, u32 value,
                                u32 mask, bool clear_full)
{
        struct ipa *ipa = container_of(trans->gsi, struct ipa, gsi);
        struct ipa_cmd_register_write *payload;
        union ipa_cmd_payload *cmd_payload;
        u32 opcode = IPA_CMD_REGISTER_WRITE;
        dma_addr_t payload_addr;
        u32 clear_option;
        u32 options;
        u16 flags;

        /* pipeline_clear_src_grp is not used */
        clear_option = clear_full ? pipeline_clear_full : pipeline_clear_hps;

        /* IPA v4.0+ represents the pipeline clear options in the opcode.  It
         * also supports a larger offset by encoding additional high-order
         * bits in the payload flags field.
         */
        if (ipa->version >= IPA_VERSION_4_0) {
                u16 offset_high;
                u32 val;

                /* Opcode encodes pipeline clear options */
                /* SKIP_CLEAR is always 0 (don't skip pipeline clear) */
                val = u16_encode_bits(clear_option,
                                      REGISTER_WRITE_OPCODE_CLEAR_OPTION_FMASK);
                opcode |= val;

                /* Extract the high 4 bits from the offset */
                offset_high = (u16)u32_get_bits(offset, GENMASK(19, 16));
                offset &= (1 << 16) - 1;

                /* Extract the top 4 bits and encode it into the flags field */
                flags = u16_encode_bits(offset_high,
                                REGISTER_WRITE_FLAGS_OFFSET_HIGH_FMASK);
                options = 0;    /* reserved */

        } else {
                flags = 0;      /* SKIP_CLEAR flag is always 0 */
                options = u16_encode_bits(clear_option,
                                          REGISTER_WRITE_CLEAR_OPTIONS_FMASK);
        }

        cmd_payload = ipa_cmd_payload_alloc(ipa, &payload_addr);
        payload = &cmd_payload->register_write;

        payload->flags = cpu_to_le16(flags);
        payload->offset = cpu_to_le16((u16)offset);
        payload->value = cpu_to_le32(value);
        payload->value_mask = cpu_to_le32(mask);
        payload->clear_options = cpu_to_le32(options);

        gsi_trans_cmd_add(trans, payload, sizeof(*payload), payload_addr,
                          DMA_NONE, opcode);
}

/* Skip IP packet processing on the next data transfer on a TX channel */
static void ipa_cmd_ip_packet_init_add(struct gsi_trans *trans, u8 endpoint_id)
{
        struct ipa *ipa = container_of(trans->gsi, struct ipa, gsi);
        enum ipa_cmd_opcode opcode = IPA_CMD_IP_PACKET_INIT;
        enum dma_data_direction direction = DMA_TO_DEVICE;
        struct ipa_cmd_ip_packet_init *payload;
        union ipa_cmd_payload *cmd_payload;
        dma_addr_t payload_addr;

        /* assert(endpoint_id <
                  field_max(IPA_PACKET_INIT_DEST_ENDPOINT_FMASK)); */

        cmd_payload = ipa_cmd_payload_alloc(ipa, &payload_addr);
        payload = &cmd_payload->ip_packet_init;

        payload->dest_endpoint = u8_encode_bits(endpoint_id,
                                        IPA_PACKET_INIT_DEST_ENDPOINT_FMASK);

        gsi_trans_cmd_add(trans, payload, sizeof(*payload), payload_addr,
                          direction, opcode);
}

/* Use a DMA command to read or write a block of IPA-resident memory */
void ipa_cmd_dma_shared_mem_add(struct gsi_trans *trans, u32 offset, u16 size,
                                dma_addr_t addr, bool toward_ipa)
{
        struct ipa *ipa = container_of(trans->gsi, struct ipa, gsi);
        enum ipa_cmd_opcode opcode = IPA_CMD_DMA_SHARED_MEM;
        struct ipa_cmd_hw_dma_mem_mem *payload;
        union ipa_cmd_payload *cmd_payload;
        enum dma_data_direction direction;
        dma_addr_t payload_addr;
        u16 flags;

        /* size and offset must fit in 16 bit fields */
        /* assert(size > 0 && size <= U16_MAX); */
        /* assert(offset <= U16_MAX && ipa->mem_offset <= U16_MAX - offset); */

        offset += ipa->mem_offset;

        cmd_payload = ipa_cmd_payload_alloc(ipa, &payload_addr);
        payload = &cmd_payload->dma_shared_mem;

        /* payload->clear_after_read was reserved prior to IPA v4.0.  It's
         * never needed for current code, so it's 0 regardless of version.
         */
        payload->size = cpu_to_le16(size);
        payload->local_addr = cpu_to_le16(offset);
        /* payload->flags:
         *   direction:         0 = write to IPA, 1 read from IPA
         * Starting at v4.0 these are reserved; either way, all zero:
         *   pipeline clear:    0 = wait for pipeline clear (don't skip)
         *   clear_options:     0 = pipeline_clear_hps
         * Instead, for v4.0+ these are encoded in the opcode.  But again
         * since both values are 0 we won't bother OR'ing them in.
         */
        flags = toward_ipa ? 0 : DMA_SHARED_MEM_FLAGS_DIRECTION_FMASK;
        payload->flags = cpu_to_le16(flags);
        payload->system_addr = cpu_to_le64(addr);

        direction = toward_ipa ? DMA_TO_DEVICE : DMA_FROM_DEVICE;

        gsi_trans_cmd_add(trans, payload, sizeof(*payload), payload_addr,
                          direction, opcode);
}

static void ipa_cmd_ip_tag_status_add(struct gsi_trans *trans)
{
        struct ipa *ipa = container_of(trans->gsi, struct ipa, gsi);
        enum ipa_cmd_opcode opcode = IPA_CMD_IP_PACKET_TAG_STATUS;
        enum dma_data_direction direction = DMA_TO_DEVICE;
        struct ipa_cmd_ip_packet_tag_status *payload;
        union ipa_cmd_payload *cmd_payload;
        dma_addr_t payload_addr;

        /* assert(tag <= field_max(IP_PACKET_TAG_STATUS_TAG_FMASK)); */

        cmd_payload = ipa_cmd_payload_alloc(ipa, &payload_addr);
        payload = &cmd_payload->ip_packet_tag_status;

        payload->tag = le64_encode_bits(0, IP_PACKET_TAG_STATUS_TAG_FMASK);

        gsi_trans_cmd_add(trans, payload, sizeof(*payload), payload_addr,
                          direction, opcode);
}

/* Issue a small command TX data transfer */
static void ipa_cmd_transfer_add(struct gsi_trans *trans)
{
        struct ipa *ipa = container_of(trans->gsi, struct ipa, gsi);
        enum dma_data_direction direction = DMA_TO_DEVICE;
        enum ipa_cmd_opcode opcode = IPA_CMD_NONE;
        union ipa_cmd_payload *payload;
        dma_addr_t payload_addr;

        /* Just transfer a zero-filled payload structure */
        payload = ipa_cmd_payload_alloc(ipa, &payload_addr);

        gsi_trans_cmd_add(trans, payload, sizeof(*payload), payload_addr,
                          direction, opcode);
}

/* Add immediate commands to a transaction to clear the hardware pipeline */
void ipa_cmd_pipeline_clear_add(struct gsi_trans *trans)
{
        struct ipa *ipa = container_of(trans->gsi, struct ipa, gsi);
        struct ipa_endpoint *endpoint;

        /* This will complete when the transfer is received */
        reinit_completion(&ipa->completion);

        /* Issue a no-op register write command (mask 0 means no write) */
        ipa_cmd_register_write_add(trans, 0, 0, 0, true);

        /* Send a data packet through the IPA pipeline.  The packet_init
         * command says to send the next packet directly to the exception
         * endpoint without any other IPA processing.  The tag_status
         * command requests that status be generated on completion of
         * that transfer, and that it will be tagged with a value.
         * Finally, the transfer command sends a small packet of data
         * (instead of a command) using the command endpoint.
         */
        endpoint = ipa->name_map[IPA_ENDPOINT_AP_LAN_RX];
        ipa_cmd_ip_packet_init_add(trans, endpoint->endpoint_id);
        ipa_cmd_ip_tag_status_add(trans);
        ipa_cmd_transfer_add(trans);
}

/* Returns the number of commands required to clear the pipeline */
u32 ipa_cmd_pipeline_clear_count(void)
{
        return 4;
}

void ipa_cmd_pipeline_clear_wait(struct ipa *ipa)
{
        wait_for_completion(&ipa->completion);
}

void ipa_cmd_pipeline_clear(struct ipa *ipa)
{
        u32 count = ipa_cmd_pipeline_clear_count();
        struct gsi_trans *trans;

        trans = ipa_cmd_trans_alloc(ipa, count);
        if (trans) {
                ipa_cmd_pipeline_clear_add(trans);
                gsi_trans_commit_wait(trans);
                ipa_cmd_pipeline_clear_wait(ipa);
        } else {
                dev_err(&ipa->pdev->dev,
                        "error allocating %u entry tag transaction\n", count);
        }
}

static struct ipa_cmd_info *
ipa_cmd_info_alloc(struct ipa_endpoint *endpoint, u32 tre_count)
{
        struct gsi_channel *channel;

        channel = &endpoint->ipa->gsi.channel[endpoint->channel_id];

        return gsi_trans_pool_alloc(&channel->trans_info.info_pool, tre_count);
}

/* Allocate a transaction for the command TX endpoint */
struct gsi_trans *ipa_cmd_trans_alloc(struct ipa *ipa, u32 tre_count)
{
        struct ipa_endpoint *endpoint;
        struct gsi_trans *trans;

        endpoint = ipa->name_map[IPA_ENDPOINT_AP_COMMAND_TX];

        trans = gsi_channel_trans_alloc(&ipa->gsi, endpoint->channel_id,
                                        tre_count, DMA_NONE);
        if (trans)
                trans->info = ipa_cmd_info_alloc(endpoint, tre_count);

        return trans;
}