// SPDX-License-Identifier: GPL-2.0+
/*
 * Mellanox register access driver
 *
 * Copyright (C) 2018 Mellanox Technologies
 * Copyright (C) 2018 Vadim Pasternak <vadimp@mellanox.com>
 */

#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/module.h>
#include <linux/platform_data/mlxreg.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>

/* Attribute parameters. */
#define MLXREG_IO_ATT_SIZE      10
#define MLXREG_IO_ATT_NUM       96

/**
 * struct mlxreg_io_priv_data - driver's private data:
 *
 * @pdev: platform device;
 * @pdata: platform data;
 * @hwmon: hwmon device;
 * @mlxreg_io_attr: sysfs attributes array;
 * @mlxreg_io_dev_attr: sysfs sensor device attribute array;
 * @group: sysfs attribute group;
 * @groups: list of sysfs attribute group for hwmon registration;
 * @regsize: size of a register value;
 * @io_lock: user access locking;
 */
struct mlxreg_io_priv_data {
        struct platform_device *pdev;
        struct mlxreg_core_platform_data *pdata;
        struct device *hwmon;
        struct attribute *mlxreg_io_attr[MLXREG_IO_ATT_NUM + 1];
        struct sensor_device_attribute mlxreg_io_dev_attr[MLXREG_IO_ATT_NUM];
        struct attribute_group group;
        const struct attribute_group *groups[2];
        int regsize;
        struct mutex io_lock; /* Protects user access. */
};

static int
mlxreg_io_get_reg(void *regmap, struct mlxreg_core_data *data, u32 in_val,
                  bool rw_flag, int regsize, u32 *regval)
{
        int i, val, ret;

        ret = regmap_read(regmap, data->reg, regval);
        if (ret)
                goto access_error;

        /*
         * There are four kinds of attributes: single bit, full register's
         * bits, bit sequence, bits in few registers For the first kind field
         * mask indicates which bits are not related and field bit is set zero.
         * For the second kind field mask is set to zero and field bit is set
         * with all bits one. No special handling for such kind of attributes -
         * pass value as is. For the third kind, the field mask indicates which
         * bits are related and the field bit is set to the first bit number
         * (from 1 to 32) is the bit sequence. For the fourth kind - the number
         * of registers which should be read for getting an attribute are
         * specified through 'data->regnum' field.
         */
        if (!data->bit) {
                /* Single bit. */
                if (rw_flag) {
                        /* For show: expose effective bit value as 0 or 1. */
                        *regval = !!(*regval & ~data->mask);
                } else {
                        /* For store: set effective bit value. */
                        *regval &= data->mask;
                        if (in_val)
                                *regval |= ~data->mask;
                }
        } else if (data->mask) {
                /* Bit sequence. */
                if (rw_flag) {
                        /* For show: mask and shift right. */
                        *regval = ror32(*regval & data->mask, (data->bit - 1));
                } else {
                        /* For store: shift to the position and mask. */
                        in_val = rol32(in_val, data->bit - 1) & data->mask;
                        /* Clear relevant bits and set them to new value. */
                        *regval = (*regval & ~data->mask) | in_val;
                }
        } else {
                /*
                 * Some attributes could occupied few registers in case regmap
                 * bit size is 8 or 16. Compose such attributes from 'regnum'
                 * registers. Such attributes contain read-only data.
                 */
                for (i = 1; i < data->regnum; i++) {
                        ret = regmap_read(regmap, data->reg + i, &val);
                        if (ret)
                                goto access_error;

                        *regval |= rol32(val, regsize * i * 8);
                }
        }

access_error:
        return ret;
}

static ssize_t
mlxreg_io_attr_show(struct device *dev, struct device_attribute *attr,
                    char *buf)
{
        struct mlxreg_io_priv_data *priv = dev_get_drvdata(dev);
        int index = to_sensor_dev_attr(attr)->index;
        struct mlxreg_core_data *data = priv->pdata->data + index;
        u32 regval = 0;
        int ret;

        mutex_lock(&priv->io_lock);

        ret = mlxreg_io_get_reg(priv->pdata->regmap, data, 0, true,
                                priv->regsize, &regval);
        if (ret)
                goto access_error;

        mutex_unlock(&priv->io_lock);

        return sysfs_emit(buf, "%u\n", regval);

access_error:
        mutex_unlock(&priv->io_lock);
        return ret;
}

static ssize_t
mlxreg_io_attr_store(struct device *dev, struct device_attribute *attr,
                     const char *buf, size_t len)
{
        struct mlxreg_io_priv_data *priv = dev_get_drvdata(dev);
        int index = to_sensor_dev_attr(attr)->index;
        struct mlxreg_core_data *data = priv->pdata->data + index;
        u32 input_val, regval;
        int ret;

        if (len > MLXREG_IO_ATT_SIZE)
                return -EINVAL;

        /* Convert buffer to input value. */
        ret = kstrtou32(buf, 0, &input_val);
        if (ret)
                return ret;

        mutex_lock(&priv->io_lock);

        ret = mlxreg_io_get_reg(priv->pdata->regmap, data, input_val, false,
                                priv->regsize, &regval);
        if (ret)
                goto access_error;

        ret = regmap_write(priv->pdata->regmap, data->reg, regval);
        if (ret)
                goto access_error;

        mutex_unlock(&priv->io_lock);

        return len;

access_error:
        mutex_unlock(&priv->io_lock);
        dev_err(&priv->pdev->dev, "Bus access error\n");
        return ret;
}

static struct device_attribute mlxreg_io_devattr_rw = {
        .show   = mlxreg_io_attr_show,
        .store  = mlxreg_io_attr_store,
};

static int mlxreg_io_attr_init(struct mlxreg_io_priv_data *priv)
{
        int i;

        priv->group.attrs = devm_kcalloc(&priv->pdev->dev,
                                         priv->pdata->counter,
                                         sizeof(struct attribute *),
                                         GFP_KERNEL);
        if (!priv->group.attrs)
                return -ENOMEM;

        for (i = 0; i < priv->pdata->counter; i++) {
                priv->mlxreg_io_attr[i] =
                                &priv->mlxreg_io_dev_attr[i].dev_attr.attr;
                memcpy(&priv->mlxreg_io_dev_attr[i].dev_attr,
                       &mlxreg_io_devattr_rw, sizeof(struct device_attribute));

                /* Set attribute name as a label. */
                priv->mlxreg_io_attr[i]->name =
                                devm_kasprintf(&priv->pdev->dev, GFP_KERNEL,
                                               priv->pdata->data[i].label);

                if (!priv->mlxreg_io_attr[i]->name) {
                        dev_err(&priv->pdev->dev, "Memory allocation failed for sysfs attribute %d.\n",
                                i + 1);
                        return -ENOMEM;
                }

                priv->mlxreg_io_dev_attr[i].dev_attr.attr.mode =
                                                priv->pdata->data[i].mode;
                priv->mlxreg_io_dev_attr[i].dev_attr.attr.name =
                                        priv->mlxreg_io_attr[i]->name;
                priv->mlxreg_io_dev_attr[i].index = i;
                sysfs_attr_init(&priv->mlxreg_io_dev_attr[i].dev_attr.attr);
        }

        priv->group.attrs = priv->mlxreg_io_attr;
        priv->groups[0] = &priv->group;
        priv->groups[1] = NULL;

        return 0;
}

static int mlxreg_io_probe(struct platform_device *pdev)
{
        struct mlxreg_io_priv_data *priv;
        int err;

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

        priv->pdata = dev_get_platdata(&pdev->dev);
        if (!priv->pdata) {
                dev_err(&pdev->dev, "Failed to get platform data.\n");
                return -EINVAL;
        }

        priv->pdev = pdev;
        priv->regsize = regmap_get_val_bytes(priv->pdata->regmap);
        if (priv->regsize < 0)
                return priv->regsize;

        err = mlxreg_io_attr_init(priv);
        if (err) {
                dev_err(&priv->pdev->dev, "Failed to allocate attributes: %d\n",
                        err);
                return err;
        }

        priv->hwmon = devm_hwmon_device_register_with_groups(&pdev->dev,
                                                             "mlxreg_io",
                                                              priv,
                                                              priv->groups);
        if (IS_ERR(priv->hwmon)) {
                dev_err(&pdev->dev, "Failed to register hwmon device %ld\n",
                        PTR_ERR(priv->hwmon));
                return PTR_ERR(priv->hwmon);
        }

        mutex_init(&priv->io_lock);
        dev_set_drvdata(&pdev->dev, priv);

        return 0;
}

static void mlxreg_io_remove(struct platform_device *pdev)
{
        struct mlxreg_io_priv_data *priv = dev_get_drvdata(&pdev->dev);

        mutex_destroy(&priv->io_lock);
}

static struct platform_driver mlxreg_io_driver = {
        .driver = {
            .name = "mlxreg-io",
        },
        .probe = mlxreg_io_probe,
        .remove = mlxreg_io_remove,
};

module_platform_driver(mlxreg_io_driver);

MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
MODULE_DESCRIPTION("Mellanox regmap I/O access driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:mlxreg-io");