system/ulib/ddk/include/ddk/protocol/i2c-lib.h

// Copyright 2018 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#pragma once

#include <string.h>

#include <ddk/protocol/i2c.h>
#include <lib/sync/completion.h>
#include <zircon/assert.h>
#include <zircon/compiler.h>
#include <zircon/types.h>

__BEGIN_CDECLS;

typedef struct {
    size_t length;
    bool is_read;
    bool stop;
} __PACKED i2c_rpc_op_t;

// Writes and reads data on an i2c channel. If both write_length and read_length
// are greater than zero, this call will perform a write operation immediately followed
// by a read operation with no other traffic occurring on the bus in between.
// If read_length is zero, then i2c_write_read will only perform a write operation,
// and if write_length is zero, then it will only perform a read operation.
// The results of the operation are returned asynchronously via the transact_cb.
// The cookie parameter can be used to pass your own private data to the transact_cb callback.
static inline void i2c_write_read(const i2c_protocol_t* i2c, const void* write_buf,
                                  size_t write_length, size_t read_length,
                                  i2c_transact_callback transact_cb, void* cookie) {
    i2c_op_t ops[2];
    size_t count = 0;
    if (write_length) {
        ops[count].data_buffer = (void*)write_buf;
        ops[count].data_size = (uint32_t)write_length;
        ops[count].is_read = false;
        ops[count].stop = !read_length;
        count++;
    }
    if (read_length) {
        ops[count].data_buffer = NULL;
        ops[count].data_size = (uint32_t)read_length;
        ops[count].is_read = true;
        ops[count].stop = true;
        count++;
    }
    i2c_transact(i2c, ops, count, transact_cb, cookie);
}

typedef struct {
    sync_completion_t completion;
    void* read_buf;
    size_t read_length;
    zx_status_t result;
} i2c_write_read_ctx_t;

static inline void i2c_write_read_sync_cb(void* cookie, zx_status_t status, const i2c_op_t* ops,
                                          size_t cnt) {
    i2c_write_read_ctx_t* ctx = (i2c_write_read_ctx_t*)cookie;
    ctx->result = status;
    if (status == ZX_OK && ctx->read_buf && ctx->read_length) {
        ZX_DEBUG_ASSERT(cnt == 1);
        memcpy(ctx->read_buf, ops[0].data_buffer, ctx->read_length);
    }

    sync_completion_signal(&ctx->completion);
}

static inline zx_status_t i2c_write_read_sync(const i2c_protocol_t* i2c, const void* write_buf,
                                              size_t write_length, void* read_buf,
                                              size_t read_length) {
    i2c_write_read_ctx_t ctx;
    sync_completion_reset(&ctx.completion);
    ctx.read_buf = read_buf;
    ctx.read_length = read_length;

    i2c_write_read(i2c, write_buf, write_length, read_length, i2c_write_read_sync_cb, &ctx);
    zx_status_t status = sync_completion_wait(&ctx.completion, ZX_TIME_INFINITE);
    if (status == ZX_OK) {
        return ctx.result;
    } else {
        return status;
    }
}

static inline zx_status_t i2c_write_sync(const i2c_protocol_t* i2c, const void* write_buf,
                                         size_t write_length) {
    return i2c_write_read_sync(i2c, write_buf, write_length, NULL, 0);
}

static inline zx_status_t i2c_read_sync(const i2c_protocol_t* i2c, void* read_buf,
                                        size_t read_length) {
    return i2c_write_read_sync(i2c, NULL, 0, read_buf, read_length);
}

__END_CDECLS;