// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/i2c/busses/i2c-tegra-bpmp.c
 *
 * Copyright (c) 2016 NVIDIA Corporation.  All rights reserved.
 *
 * Author: Shardar Shariff Md <smohammed@nvidia.com>
 */

#include <linux/err.h>
#include <linux/i2c.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>

#include <soc/tegra/bpmp-abi.h>
#include <soc/tegra/bpmp.h>

/*
 * Serialized I2C message header size is 6 bytes and includes address, flags
 * and length
 */
#define SERIALI2C_HDR_SIZE 6

struct tegra_bpmp_i2c {
        struct i2c_adapter adapter;
        struct device *dev;

        struct tegra_bpmp *bpmp;
        unsigned int bus;
};

/*
 * Linux flags are translated to BPMP defined I2C flags that are used in BPMP
 * firmware I2C driver to avoid any issues in future if Linux I2C flags are
 * changed.
 */
static void tegra_bpmp_xlate_flags(u16 flags, u16 *out)
{
        if (flags & I2C_M_TEN)
                *out |= SERIALI2C_TEN;

        if (flags & I2C_M_RD)
                *out |= SERIALI2C_RD;

        if (flags & I2C_M_STOP)
                *out |= SERIALI2C_STOP;

        if (flags & I2C_M_NOSTART)
                *out |= SERIALI2C_NOSTART;

        if (flags & I2C_M_REV_DIR_ADDR)
                *out |= SERIALI2C_REV_DIR_ADDR;

        if (flags & I2C_M_IGNORE_NAK)
                *out |= SERIALI2C_IGNORE_NAK;

        if (flags & I2C_M_NO_RD_ACK)
                *out |= SERIALI2C_NO_RD_ACK;

        if (flags & I2C_M_RECV_LEN)
                *out |= SERIALI2C_RECV_LEN;
}

/*
 * The serialized I2C format is simply the following:
 * [addr little-endian][flags little-endian][len little-endian][data if write]
 * [addr little-endian][flags little-endian][len little-endian][data if write]
 *  ...
 *
 * The flags are translated from Linux kernel representation to seriali2c
 * representation. Any undefined flag being set causes an error.
 *
 * The data is there only for writes. Reads have the data transferred in the
 * other direction, and thus data is not present.
 *
 * See deserialize_i2c documentation for the data format in the other direction.
 */
static void tegra_bpmp_serialize_i2c_msg(struct tegra_bpmp_i2c *i2c,
                                        struct mrq_i2c_request *request,
                                        struct i2c_msg *msgs,
                                        unsigned int num)
{
        char *buf = request->xfer.data_buf;
        unsigned int i, j, pos = 0;

        for (i = 0; i < num; i++) {
                struct i2c_msg *msg = &msgs[i];
                u16 flags = 0;

                tegra_bpmp_xlate_flags(msg->flags, &flags);

                buf[pos++] = msg->addr & 0xff;
                buf[pos++] = (msg->addr & 0xff00) >> 8;
                buf[pos++] = flags & 0xff;
                buf[pos++] = (flags & 0xff00) >> 8;
                buf[pos++] = msg->len & 0xff;
                buf[pos++] = (msg->len & 0xff00) >> 8;

                if ((flags & SERIALI2C_RD) == 0) {
                        for (j = 0; j < msg->len; j++)
                                buf[pos++] = msg->buf[j];
                }
        }

        request->xfer.data_size = pos;
}

/*
 * The data in the BPMP -> CPU direction is composed of sequential blocks for
 * those messages that have I2C_M_RD. So, for example, if you have:
 *
 * - !I2C_M_RD, len == 5, data == a0 01 02 03 04
 * - !I2C_M_RD, len == 1, data == a0
 * - I2C_M_RD, len == 2, data == [uninitialized buffer 1]
 * - !I2C_M_RD, len == 1, data == a2
 * - I2C_M_RD, len == 2, data == [uninitialized buffer 2]
 *
 * ...then the data in the BPMP -> CPU direction would be 4 bytes total, and
 * would contain 2 bytes that will go to uninitialized buffer 1, and 2 bytes
 * that will go to uninitialized buffer 2.
 */
static int tegra_bpmp_i2c_deserialize(struct tegra_bpmp_i2c *i2c,
                                      struct mrq_i2c_response *response,
                                      struct i2c_msg *msgs,
                                      unsigned int num)
{
        size_t size = response->xfer.data_size, len = 0, pos = 0;
        char *buf = response->xfer.data_buf;
        unsigned int i;

        for (i = 0; i < num; i++)
                if (msgs[i].flags & I2C_M_RD)
                        len += msgs[i].len;

        if (len != size)
                return -EINVAL;

        for (i = 0; i < num; i++) {
                if (msgs[i].flags & I2C_M_RD) {
                        memcpy(msgs[i].buf, buf + pos, msgs[i].len);
                        pos += msgs[i].len;
                }
        }

        return 0;
}

static int tegra_bpmp_i2c_msg_len_check(struct i2c_msg *msgs, unsigned int num)
{
        size_t tx_len = 0, rx_len = 0;
        unsigned int i;

        for (i = 0; i < num; i++)
                if (!(msgs[i].flags & I2C_M_RD))
                        tx_len += SERIALI2C_HDR_SIZE + msgs[i].len;

        if (tx_len > TEGRA_I2C_IPC_MAX_IN_BUF_SIZE)
                return -EINVAL;

        for (i = 0; i < num; i++)
                if ((msgs[i].flags & I2C_M_RD))
                        rx_len += msgs[i].len;

        if (rx_len > TEGRA_I2C_IPC_MAX_OUT_BUF_SIZE)
                return -EINVAL;

        return 0;
}

static int tegra_bpmp_i2c_msg_xfer(struct tegra_bpmp_i2c *i2c,
                                   struct mrq_i2c_request *request,
                                   struct mrq_i2c_response *response,
                                   bool atomic)
{
        struct tegra_bpmp_message msg;
        int err;

        request->cmd = CMD_I2C_XFER;
        request->xfer.bus_id = i2c->bus;

        memset(&msg, 0, sizeof(msg));
        msg.mrq = MRQ_I2C;
        msg.tx.data = request;
        msg.tx.size = sizeof(*request);
        msg.rx.data = response;
        msg.rx.size = sizeof(*response);

        if (atomic)
                err = tegra_bpmp_transfer_atomic(i2c->bpmp, &msg);
        else
                err = tegra_bpmp_transfer(i2c->bpmp, &msg);

        if (err < 0) {
                dev_err(i2c->dev, "failed to transfer message: %d\n", err);
                return err;
        }

        if (msg.rx.ret != 0) {
                if (msg.rx.ret == -BPMP_EAGAIN) {
                        dev_dbg(i2c->dev, "arbitration lost\n");
                        return -EAGAIN;
                }

                if (msg.rx.ret == -BPMP_ETIMEDOUT) {
                        dev_dbg(i2c->dev, "timeout\n");
                        return -ETIMEDOUT;
                }

                if (msg.rx.ret == -BPMP_ENXIO) {
                        dev_dbg(i2c->dev, "NAK\n");
                        return -ENXIO;
                }

                dev_err(i2c->dev, "transaction failed: %d\n", msg.rx.ret);
                return -EIO;
        }

        return 0;
}

static int tegra_bpmp_i2c_xfer_common(struct i2c_adapter *adapter,
                                      struct i2c_msg *msgs, int num,
                                      bool atomic)
{
        struct tegra_bpmp_i2c *i2c = i2c_get_adapdata(adapter);
        struct mrq_i2c_response response;
        struct mrq_i2c_request request;
        int err;

        err = tegra_bpmp_i2c_msg_len_check(msgs, num);
        if (err < 0) {
                dev_err(i2c->dev, "unsupported message length\n");
                return err;
        }

        memset(&request, 0, sizeof(request));
        memset(&response, 0, sizeof(response));

        tegra_bpmp_serialize_i2c_msg(i2c, &request, msgs, num);
        err = tegra_bpmp_i2c_msg_xfer(i2c, &request, &response, atomic);
        if (err < 0) {
                dev_err(i2c->dev, "failed to transfer message: %d\n", err);
                return err;
        }

        err = tegra_bpmp_i2c_deserialize(i2c, &response, msgs, num);
        if (err < 0) {
                dev_err(i2c->dev, "failed to deserialize message: %d\n", err);
                return err;
        }

        return num;
}

static int tegra_bpmp_i2c_xfer(struct i2c_adapter *adapter,
                               struct i2c_msg *msgs, int num)
{
        return tegra_bpmp_i2c_xfer_common(adapter, msgs, num, false);
}

static int tegra_bpmp_i2c_xfer_atomic(struct i2c_adapter *adapter,
                                      struct i2c_msg *msgs, int num)
{
        return tegra_bpmp_i2c_xfer_common(adapter, msgs, num, true);
}

static u32 tegra_bpmp_i2c_func(struct i2c_adapter *adapter)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
               I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_NOSTART;
}

static const struct i2c_algorithm tegra_bpmp_i2c_algo = {
        .xfer = tegra_bpmp_i2c_xfer,
        .xfer_atomic = tegra_bpmp_i2c_xfer_atomic,
        .functionality = tegra_bpmp_i2c_func,
};

static int tegra_bpmp_i2c_probe(struct platform_device *pdev)
{
        struct tegra_bpmp_i2c *i2c;
        u32 value;
        int err;

        i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
        if (!i2c)
                return -ENOMEM;

        i2c->dev = &pdev->dev;

        i2c->bpmp = dev_get_drvdata(pdev->dev.parent);
        if (!i2c->bpmp)
                return -ENODEV;

        err = of_property_read_u32(pdev->dev.of_node, "nvidia,bpmp-bus-id",
                                   &value);
        if (err < 0)
                return err;

        i2c->bus = value;

        i2c_set_adapdata(&i2c->adapter, i2c);
        i2c->adapter.owner = THIS_MODULE;
        strscpy(i2c->adapter.name, "Tegra BPMP I2C adapter",
                sizeof(i2c->adapter.name));
        i2c->adapter.algo = &tegra_bpmp_i2c_algo;
        i2c->adapter.dev.parent = &pdev->dev;
        i2c->adapter.dev.of_node = pdev->dev.of_node;

        platform_set_drvdata(pdev, i2c);

        return i2c_add_adapter(&i2c->adapter);
}

static void tegra_bpmp_i2c_remove(struct platform_device *pdev)
{
        struct tegra_bpmp_i2c *i2c = platform_get_drvdata(pdev);

        i2c_del_adapter(&i2c->adapter);
}

static const struct of_device_id tegra_bpmp_i2c_of_match[] = {
        { .compatible = "nvidia,tegra186-bpmp-i2c", },
        { }
};
MODULE_DEVICE_TABLE(of, tegra_bpmp_i2c_of_match);

static struct platform_driver tegra_bpmp_i2c_driver = {
        .driver = {
                .name = "tegra-bpmp-i2c",
                .of_match_table = tegra_bpmp_i2c_of_match,
        },
        .probe = tegra_bpmp_i2c_probe,
        .remove = tegra_bpmp_i2c_remove,
};
module_platform_driver(tegra_bpmp_i2c_driver);

MODULE_DESCRIPTION("NVIDIA Tegra BPMP I2C bus controller driver");
MODULE_AUTHOR("Shardar Shariff Md <smohammed@nvidia.com>");
MODULE_AUTHOR("Juha-Matti Tilli");
MODULE_LICENSE("GPL v2");