// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for the Diolan DLN-2 USB-I2C adapter
 *
 * Copyright (c) 2014 Intel Corporation
 *
 * Derived from:
 *  i2c-diolan-u2c.c
 *  Copyright (c) 2010-2011 Ericsson AB
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/platform_device.h>
#include <linux/mfd/dln2.h>
#include <linux/acpi.h>

#define DLN2_I2C_MODULE_ID              0x03
#define DLN2_I2C_CMD(cmd)               DLN2_CMD(cmd, DLN2_I2C_MODULE_ID)

/* I2C commands */
#define DLN2_I2C_GET_PORT_COUNT         DLN2_I2C_CMD(0x00)
#define DLN2_I2C_ENABLE                 DLN2_I2C_CMD(0x01)
#define DLN2_I2C_DISABLE                DLN2_I2C_CMD(0x02)
#define DLN2_I2C_IS_ENABLED             DLN2_I2C_CMD(0x03)
#define DLN2_I2C_WRITE                  DLN2_I2C_CMD(0x06)
#define DLN2_I2C_READ                   DLN2_I2C_CMD(0x07)
#define DLN2_I2C_SCAN_DEVICES           DLN2_I2C_CMD(0x08)
#define DLN2_I2C_PULLUP_ENABLE          DLN2_I2C_CMD(0x09)
#define DLN2_I2C_PULLUP_DISABLE         DLN2_I2C_CMD(0x0A)
#define DLN2_I2C_PULLUP_IS_ENABLED      DLN2_I2C_CMD(0x0B)
#define DLN2_I2C_TRANSFER               DLN2_I2C_CMD(0x0C)
#define DLN2_I2C_SET_MAX_REPLY_COUNT    DLN2_I2C_CMD(0x0D)
#define DLN2_I2C_GET_MAX_REPLY_COUNT    DLN2_I2C_CMD(0x0E)

#define DLN2_I2C_MAX_XFER_SIZE          256
#define DLN2_I2C_BUF_SIZE               (DLN2_I2C_MAX_XFER_SIZE + 16)

struct dln2_i2c {
        struct platform_device *pdev;
        struct i2c_adapter adapter;
        u8 port;
        /*
         * Buffer to hold the packet for read or write transfers. One is enough
         * since we can't have multiple transfers in parallel on the i2c bus.
         */
        void *buf;
};

static int dln2_i2c_enable(struct dln2_i2c *dln2, bool enable)
{
        u16 cmd;
        struct {
                u8 port;
        } tx;

        tx.port = dln2->port;

        if (enable)
                cmd = DLN2_I2C_ENABLE;
        else
                cmd = DLN2_I2C_DISABLE;

        return dln2_transfer_tx(dln2->pdev, cmd, &tx, sizeof(tx));
}

static int dln2_i2c_write(struct dln2_i2c *dln2, u8 addr,
                          u8 *data, u16 data_len)
{
        int ret;
        struct {
                u8 port;
                u8 addr;
                u8 mem_addr_len;
                __le32 mem_addr;
                __le16 buf_len;
                u8 buf[DLN2_I2C_MAX_XFER_SIZE];
        } __packed *tx = dln2->buf;
        unsigned len;

        BUILD_BUG_ON(sizeof(*tx) > DLN2_I2C_BUF_SIZE);

        tx->port = dln2->port;
        tx->addr = addr;
        tx->mem_addr_len = 0;
        tx->mem_addr = 0;
        tx->buf_len = cpu_to_le16(data_len);
        memcpy(tx->buf, data, data_len);

        len = sizeof(*tx) + data_len - DLN2_I2C_MAX_XFER_SIZE;
        ret = dln2_transfer_tx(dln2->pdev, DLN2_I2C_WRITE, tx, len);
        if (ret < 0)
                return ret;

        return data_len;
}

static int dln2_i2c_read(struct dln2_i2c *dln2, u16 addr, u8 *data,
                         u16 data_len)
{
        int ret;
        struct {
                u8 port;
                u8 addr;
                u8 mem_addr_len;
                __le32 mem_addr;
                __le16 buf_len;
        } __packed tx;
        struct {
                __le16 buf_len;
                u8 buf[DLN2_I2C_MAX_XFER_SIZE];
        } __packed *rx = dln2->buf;
        unsigned rx_len = sizeof(*rx);

        BUILD_BUG_ON(sizeof(*rx) > DLN2_I2C_BUF_SIZE);

        tx.port = dln2->port;
        tx.addr = addr;
        tx.mem_addr_len = 0;
        tx.mem_addr = 0;
        tx.buf_len = cpu_to_le16(data_len);

        ret = dln2_transfer(dln2->pdev, DLN2_I2C_READ, &tx, sizeof(tx),
                            rx, &rx_len);
        if (ret < 0)
                return ret;
        if (rx_len < sizeof(rx->buf_len) + data_len)
                return -EPROTO;
        if (le16_to_cpu(rx->buf_len) != data_len)
                return -EPROTO;

        memcpy(data, rx->buf, data_len);

        return data_len;
}

static int dln2_i2c_xfer(struct i2c_adapter *adapter,
                         struct i2c_msg *msgs, int num)
{
        struct dln2_i2c *dln2 = i2c_get_adapdata(adapter);
        struct i2c_msg *pmsg;
        int i;

        for (i = 0; i < num; i++) {
                int ret;

                pmsg = &msgs[i];

                if (pmsg->flags & I2C_M_RD) {
                        ret = dln2_i2c_read(dln2, pmsg->addr, pmsg->buf,
                                            pmsg->len);
                        if (ret < 0)
                                return ret;

                        pmsg->len = ret;
                } else {
                        ret = dln2_i2c_write(dln2, pmsg->addr, pmsg->buf,
                                             pmsg->len);
                        if (ret != pmsg->len)
                                return -EPROTO;
                }
        }

        return num;
}

static u32 dln2_i2c_func(struct i2c_adapter *a)
{
        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA |
                I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
                I2C_FUNC_SMBUS_I2C_BLOCK;
}

static const struct i2c_algorithm dln2_i2c_usb_algorithm = {
        .xfer = dln2_i2c_xfer,
        .functionality = dln2_i2c_func,
};

static const struct i2c_adapter_quirks dln2_i2c_quirks = {
        .max_read_len = DLN2_I2C_MAX_XFER_SIZE,
        .max_write_len = DLN2_I2C_MAX_XFER_SIZE,
};

static int dln2_i2c_probe(struct platform_device *pdev)
{
        int ret;
        struct dln2_i2c *dln2;
        struct device *dev = &pdev->dev;
        struct dln2_platform_data *pdata = dev_get_platdata(&pdev->dev);

        dln2 = devm_kzalloc(dev, sizeof(*dln2), GFP_KERNEL);
        if (!dln2)
                return -ENOMEM;

        dln2->buf = devm_kmalloc(dev, DLN2_I2C_BUF_SIZE, GFP_KERNEL);
        if (!dln2->buf)
                return -ENOMEM;

        dln2->pdev = pdev;
        dln2->port = pdata->port;

        /* setup i2c adapter description */
        dln2->adapter.owner = THIS_MODULE;
        dln2->adapter.class = I2C_CLASS_HWMON;
        dln2->adapter.algo = &dln2_i2c_usb_algorithm;
        dln2->adapter.quirks = &dln2_i2c_quirks;
        dln2->adapter.dev.parent = dev;
        ACPI_COMPANION_SET(&dln2->adapter.dev, ACPI_COMPANION(&pdev->dev));
        dln2->adapter.dev.of_node = dev->of_node;
        i2c_set_adapdata(&dln2->adapter, dln2);
        snprintf(dln2->adapter.name, sizeof(dln2->adapter.name), "%s-%s-%d",
                 "dln2-i2c", dev_name(pdev->dev.parent), dln2->port);

        platform_set_drvdata(pdev, dln2);

        /* initialize the i2c interface */
        ret = dln2_i2c_enable(dln2, true);
        if (ret < 0)
                return dev_err_probe(dev, ret, "failed to initialize adapter\n");

        /* and finally attach to i2c layer */
        ret = i2c_add_adapter(&dln2->adapter);
        if (ret < 0)
                goto out_disable;

        return 0;

out_disable:
        dln2_i2c_enable(dln2, false);

        return ret;
}

static void dln2_i2c_remove(struct platform_device *pdev)
{
        struct dln2_i2c *dln2 = platform_get_drvdata(pdev);

        i2c_del_adapter(&dln2->adapter);
        dln2_i2c_enable(dln2, false);
}

static struct platform_driver dln2_i2c_driver = {
        .driver.name    = "dln2-i2c",
        .probe          = dln2_i2c_probe,
        .remove         = dln2_i2c_remove,
};

module_platform_driver(dln2_i2c_driver);

MODULE_AUTHOR("Laurentiu Palcu <laurentiu.palcu@intel.com>");
MODULE_DESCRIPTION("Driver for the Diolan DLN2 I2C controller interface");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:dln2-i2c");