/*
 * max1111.c - +2.7V, Low-Power, Multichannel, Serial 8-bit ADCs
 *
 * Based on arch/arm/mach-pxa/corgi_ssp.c
 *
 * Copyright (C) 2004-2005 Richard Purdie
 *
 * Copyright (C) 2008 Marvell International Ltd.
 *      Eric Miao <eric.miao@marvell.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  publishhed by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/spi/spi.h>
#include <linux/slab.h>

enum chips { max1110, max1111, max1112, max1113 };

#define MAX1111_TX_BUF_SIZE     1
#define MAX1111_RX_BUF_SIZE     2

/* MAX1111 Commands */
#define MAX1111_CTRL_PD0      (1u << 0)
#define MAX1111_CTRL_PD1      (1u << 1)
#define MAX1111_CTRL_SGL      (1u << 2)
#define MAX1111_CTRL_UNI      (1u << 3)
#define MAX1110_CTRL_SEL_SH   (4)
#define MAX1111_CTRL_SEL_SH   (5)       /* NOTE: bit 4 is ignored */
#define MAX1111_CTRL_STR      (1u << 7)

struct max1111_data {
        struct spi_device       *spi;
        struct device           *hwmon_dev;
        struct spi_message      msg;
        struct spi_transfer     xfer[2];
        uint8_t tx_buf[MAX1111_TX_BUF_SIZE];
        uint8_t rx_buf[MAX1111_RX_BUF_SIZE];
        struct mutex            drvdata_lock;
        /* protect msg, xfer and buffers from multiple access */
        int                     sel_sh;
        int                     lsb;
};

static int max1111_read(struct device *dev, int channel)
{
        struct max1111_data *data = dev_get_drvdata(dev);
        uint8_t v1, v2;
        int err;

        /* writing to drvdata struct is not thread safe, wait on mutex */
        mutex_lock(&data->drvdata_lock);

        data->tx_buf[0] = (channel << data->sel_sh) |
                MAX1111_CTRL_PD0 | MAX1111_CTRL_PD1 |
                MAX1111_CTRL_SGL | MAX1111_CTRL_UNI | MAX1111_CTRL_STR;

        err = spi_sync(data->spi, &data->msg);
        if (err < 0) {
                dev_err(dev, "spi_sync failed with %d\n", err);
                mutex_unlock(&data->drvdata_lock);
                return err;
        }

        v1 = data->rx_buf[0];
        v2 = data->rx_buf[1];

        mutex_unlock(&data->drvdata_lock);

        if ((v1 & 0xc0) || (v2 & 0x3f))
                return -EINVAL;

        return (v1 << 2) | (v2 >> 6);
}

#ifdef CONFIG_SHARPSL_PM
static struct max1111_data *the_max1111;

int max1111_read_channel(int channel)
{
        if (!the_max1111 || !the_max1111->spi)
                return -ENODEV;

        return max1111_read(&the_max1111->spi->dev, channel);
}
EXPORT_SYMBOL(max1111_read_channel);
#endif

/*
 * NOTE: SPI devices do not have a default 'name' attribute, which is
 * likely to be used by hwmon applications to distinguish between
 * different devices, explicitly add a name attribute here.
 */
static ssize_t name_show(struct device *dev,
                         struct device_attribute *attr, char *buf)
{
        return sprintf(buf, "%s\n", to_spi_device(dev)->modalias);
}

static ssize_t show_adc(struct device *dev,
                        struct device_attribute *attr, char *buf)
{
        struct max1111_data *data = dev_get_drvdata(dev);
        int channel = to_sensor_dev_attr(attr)->index;
        int ret;

        ret = max1111_read(dev, channel);
        if (ret < 0)
                return ret;

        /*
         * Assume the reference voltage to be 2.048V or 4.096V, with an 8-bit
         * sample. The LSB weight is 8mV or 16mV depending on the chip type.
         */
        return sprintf(buf, "%d\n", ret * data->lsb);
}

#define MAX1111_ADC_ATTR(_id)           \
        SENSOR_DEVICE_ATTR(in##_id##_input, S_IRUGO, show_adc, NULL, _id)

static DEVICE_ATTR_RO(name);
static MAX1111_ADC_ATTR(0);
static MAX1111_ADC_ATTR(1);
static MAX1111_ADC_ATTR(2);
static MAX1111_ADC_ATTR(3);
static MAX1111_ADC_ATTR(4);
static MAX1111_ADC_ATTR(5);
static MAX1111_ADC_ATTR(6);
static MAX1111_ADC_ATTR(7);

static struct attribute *max1111_attributes[] = {
        &dev_attr_name.attr,
        &sensor_dev_attr_in0_input.dev_attr.attr,
        &sensor_dev_attr_in1_input.dev_attr.attr,
        &sensor_dev_attr_in2_input.dev_attr.attr,
        &sensor_dev_attr_in3_input.dev_attr.attr,
        NULL,
};

static const struct attribute_group max1111_attr_group = {
        .attrs  = max1111_attributes,
};

static struct attribute *max1110_attributes[] = {
        &sensor_dev_attr_in4_input.dev_attr.attr,
        &sensor_dev_attr_in5_input.dev_attr.attr,
        &sensor_dev_attr_in6_input.dev_attr.attr,
        &sensor_dev_attr_in7_input.dev_attr.attr,
        NULL,
};

static const struct attribute_group max1110_attr_group = {
        .attrs  = max1110_attributes,
};

static int setup_transfer(struct max1111_data *data)
{
        struct spi_message *m;
        struct spi_transfer *x;

        m = &data->msg;
        x = &data->xfer[0];

        spi_message_init(m);

        x->tx_buf = &data->tx_buf[0];
        x->len = MAX1111_TX_BUF_SIZE;
        spi_message_add_tail(x, m);

        x++;
        x->rx_buf = &data->rx_buf[0];
        x->len = MAX1111_RX_BUF_SIZE;
        spi_message_add_tail(x, m);

        return 0;
}

static int max1111_probe(struct spi_device *spi)
{
        enum chips chip = spi_get_device_id(spi)->driver_data;
        struct max1111_data *data;
        int err;

        spi->bits_per_word = 8;
        spi->mode = SPI_MODE_0;
        err = spi_setup(spi);
        if (err < 0)
                return err;

        data = devm_kzalloc(&spi->dev, sizeof(struct max1111_data), GFP_KERNEL);
        if (data == NULL)
                return -ENOMEM;

        switch (chip) {
        case max1110:
                data->lsb = 8;
                data->sel_sh = MAX1110_CTRL_SEL_SH;
                break;
        case max1111:
                data->lsb = 8;
                data->sel_sh = MAX1111_CTRL_SEL_SH;
                break;
        case max1112:
                data->lsb = 16;
                data->sel_sh = MAX1110_CTRL_SEL_SH;
                break;
        case max1113:
                data->lsb = 16;
                data->sel_sh = MAX1111_CTRL_SEL_SH;
                break;
        }
        err = setup_transfer(data);
        if (err)
                return err;

        mutex_init(&data->drvdata_lock);

        data->spi = spi;
        spi_set_drvdata(spi, data);

        err = sysfs_create_group(&spi->dev.kobj, &max1111_attr_group);
        if (err) {
                dev_err(&spi->dev, "failed to create attribute group\n");
                return err;
        }
        if (chip == max1110 || chip == max1112) {
                err = sysfs_create_group(&spi->dev.kobj, &max1110_attr_group);
                if (err) {
                        dev_err(&spi->dev,
                                "failed to create extended attribute group\n");
                        goto err_remove;
                }
        }

        data->hwmon_dev = hwmon_device_register(&spi->dev);
        if (IS_ERR(data->hwmon_dev)) {
                dev_err(&spi->dev, "failed to create hwmon device\n");
                err = PTR_ERR(data->hwmon_dev);
                goto err_remove;
        }

#ifdef CONFIG_SHARPSL_PM
        the_max1111 = data;
#endif
        return 0;

err_remove:
        sysfs_remove_group(&spi->dev.kobj, &max1110_attr_group);
        sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
        return err;
}

static int max1111_remove(struct spi_device *spi)
{
        struct max1111_data *data = spi_get_drvdata(spi);

#ifdef CONFIG_SHARPSL_PM
        the_max1111 = NULL;
#endif
        hwmon_device_unregister(data->hwmon_dev);
        sysfs_remove_group(&spi->dev.kobj, &max1110_attr_group);
        sysfs_remove_group(&spi->dev.kobj, &max1111_attr_group);
        mutex_destroy(&data->drvdata_lock);
        return 0;
}

static const struct spi_device_id max1111_ids[] = {
        { "max1110", max1110 },
        { "max1111", max1111 },
        { "max1112", max1112 },
        { "max1113", max1113 },
        { },
};
MODULE_DEVICE_TABLE(spi, max1111_ids);

static struct spi_driver max1111_driver = {
        .driver         = {
                .name   = "max1111",
        },
        .id_table       = max1111_ids,
        .probe          = max1111_probe,
        .remove         = max1111_remove,
};

module_spi_driver(max1111_driver);

MODULE_AUTHOR("Eric Miao <eric.miao@marvell.com>");
MODULE_DESCRIPTION("MAX1110/MAX1111/MAX1112/MAX1113 ADC Driver");
MODULE_LICENSE("GPL");