/*
 * jc42.c - driver for Jedec JC42.4 compliant temperature sensors
 *
 * Copyright (c) 2010  Ericsson AB.
 *
 * Derived from lm77.c by Andras BALI <drewie@freemail.hu>.
 *
 * JC42.4 compliant temperature sensors are typically used on memory modules.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/err.h>
#include <linux/mutex.h>

/* Addresses to scan */
static const unsigned short normal_i2c[] = {
        0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, I2C_CLIENT_END };

/* JC42 registers. All registers are 16 bit. */
#define JC42_REG_CAP            0x00
#define JC42_REG_CONFIG         0x01
#define JC42_REG_TEMP_UPPER     0x02
#define JC42_REG_TEMP_LOWER     0x03
#define JC42_REG_TEMP_CRITICAL  0x04
#define JC42_REG_TEMP           0x05
#define JC42_REG_MANID          0x06
#define JC42_REG_DEVICEID       0x07

/* Status bits in temperature register */
#define JC42_ALARM_CRIT_BIT     15
#define JC42_ALARM_MAX_BIT      14
#define JC42_ALARM_MIN_BIT      13

/* Configuration register defines */
#define JC42_CFG_CRIT_ONLY      (1 << 2)
#define JC42_CFG_TCRIT_LOCK     (1 << 6)
#define JC42_CFG_EVENT_LOCK     (1 << 7)
#define JC42_CFG_SHUTDOWN       (1 << 8)
#define JC42_CFG_HYST_SHIFT     9
#define JC42_CFG_HYST_MASK      (0x03 << 9)

/* Capabilities */
#define JC42_CAP_RANGE          (1 << 2)

/* Manufacturer IDs */
#define ADT_MANID               0x11d4  /* Analog Devices */
#define ATMEL_MANID             0x001f  /* Atmel */
#define ATMEL_MANID2            0x1114  /* Atmel */
#define MAX_MANID               0x004d  /* Maxim */
#define IDT_MANID               0x00b3  /* IDT */
#define MCP_MANID               0x0054  /* Microchip */
#define NXP_MANID               0x1131  /* NXP Semiconductors */
#define ONS_MANID               0x1b09  /* ON Semiconductor */
#define STM_MANID               0x104a  /* ST Microelectronics */

/* Supported chips */

/* Analog Devices */
#define ADT7408_DEVID           0x0801
#define ADT7408_DEVID_MASK      0xffff

/* Atmel */
#define AT30TS00_DEVID          0x8201
#define AT30TS00_DEVID_MASK     0xffff

#define AT30TSE004_DEVID        0x2200
#define AT30TSE004_DEVID_MASK   0xffff

/* IDT */
#define TS3000B3_DEVID          0x2903  /* Also matches TSE2002B3 */
#define TS3000B3_DEVID_MASK     0xffff

#define TS3000GB2_DEVID         0x2912  /* Also matches TSE2002GB2 */
#define TS3000GB2_DEVID_MASK    0xffff

/* Maxim */
#define MAX6604_DEVID           0x3e00
#define MAX6604_DEVID_MASK      0xffff

/* Microchip */
#define MCP9804_DEVID           0x0200
#define MCP9804_DEVID_MASK      0xfffc

#define MCP98242_DEVID          0x2000
#define MCP98242_DEVID_MASK     0xfffc

#define MCP98243_DEVID          0x2100
#define MCP98243_DEVID_MASK     0xfffc

#define MCP98244_DEVID          0x2200
#define MCP98244_DEVID_MASK     0xfffc

#define MCP9843_DEVID           0x0000  /* Also matches mcp9805 */
#define MCP9843_DEVID_MASK      0xfffe

/* NXP */
#define SE97_DEVID              0xa200
#define SE97_DEVID_MASK         0xfffc

#define SE98_DEVID              0xa100
#define SE98_DEVID_MASK         0xfffc

/* ON Semiconductor */
#define CAT6095_DEVID           0x0800  /* Also matches CAT34TS02 */
#define CAT6095_DEVID_MASK      0xffe0

/* ST Microelectronics */
#define STTS424_DEVID           0x0101
#define STTS424_DEVID_MASK      0xffff

#define STTS424E_DEVID          0x0000
#define STTS424E_DEVID_MASK     0xfffe

#define STTS2002_DEVID          0x0300
#define STTS2002_DEVID_MASK     0xffff

#define STTS2004_DEVID          0x2201
#define STTS2004_DEVID_MASK     0xffff

#define STTS3000_DEVID          0x0200
#define STTS3000_DEVID_MASK     0xffff

static u16 jc42_hysteresis[] = { 0, 1500, 3000, 6000 };

struct jc42_chips {
        u16 manid;
        u16 devid;
        u16 devid_mask;
};

static struct jc42_chips jc42_chips[] = {
        { ADT_MANID, ADT7408_DEVID, ADT7408_DEVID_MASK },
        { ATMEL_MANID, AT30TS00_DEVID, AT30TS00_DEVID_MASK },
        { ATMEL_MANID2, AT30TSE004_DEVID, AT30TSE004_DEVID_MASK },
        { IDT_MANID, TS3000B3_DEVID, TS3000B3_DEVID_MASK },
        { IDT_MANID, TS3000GB2_DEVID, TS3000GB2_DEVID_MASK },
        { MAX_MANID, MAX6604_DEVID, MAX6604_DEVID_MASK },
        { MCP_MANID, MCP9804_DEVID, MCP9804_DEVID_MASK },
        { MCP_MANID, MCP98242_DEVID, MCP98242_DEVID_MASK },
        { MCP_MANID, MCP98243_DEVID, MCP98243_DEVID_MASK },
        { MCP_MANID, MCP98244_DEVID, MCP98244_DEVID_MASK },
        { MCP_MANID, MCP9843_DEVID, MCP9843_DEVID_MASK },
        { NXP_MANID, SE97_DEVID, SE97_DEVID_MASK },
        { ONS_MANID, CAT6095_DEVID, CAT6095_DEVID_MASK },
        { NXP_MANID, SE98_DEVID, SE98_DEVID_MASK },
        { STM_MANID, STTS424_DEVID, STTS424_DEVID_MASK },
        { STM_MANID, STTS424E_DEVID, STTS424E_DEVID_MASK },
        { STM_MANID, STTS2002_DEVID, STTS2002_DEVID_MASK },
        { STM_MANID, STTS2004_DEVID, STTS2004_DEVID_MASK },
        { STM_MANID, STTS3000_DEVID, STTS3000_DEVID_MASK },
};

enum temp_index {
        t_input = 0,
        t_crit,
        t_min,
        t_max,
        t_num_temp
};

static const u8 temp_regs[t_num_temp] = {
        [t_input] = JC42_REG_TEMP,
        [t_crit] = JC42_REG_TEMP_CRITICAL,
        [t_min] = JC42_REG_TEMP_LOWER,
        [t_max] = JC42_REG_TEMP_UPPER,
};

/* Each client has this additional data */
struct jc42_data {
        struct i2c_client *client;
        struct mutex    update_lock;    /* protect register access */
        bool            extended;       /* true if extended range supported */
        bool            valid;
        unsigned long   last_updated;   /* In jiffies */
        u16             orig_config;    /* original configuration */
        u16             config;         /* current configuration */
        u16             temp[t_num_temp];/* Temperatures */
};

#define JC42_TEMP_MIN_EXTENDED  (-40000)
#define JC42_TEMP_MIN           0
#define JC42_TEMP_MAX           125000

static u16 jc42_temp_to_reg(long temp, bool extended)
{
        int ntemp = clamp_val(temp,
                              extended ? JC42_TEMP_MIN_EXTENDED :
                              JC42_TEMP_MIN, JC42_TEMP_MAX);

        /* convert from 0.001 to 0.0625 resolution */
        return (ntemp * 2 / 125) & 0x1fff;
}

static int jc42_temp_from_reg(s16 reg)
{
        reg = sign_extend32(reg, 12);

        /* convert from 0.0625 to 0.001 resolution */
        return reg * 125 / 2;
}

static struct jc42_data *jc42_update_device(struct device *dev)
{
        struct jc42_data *data = dev_get_drvdata(dev);
        struct i2c_client *client = data->client;
        struct jc42_data *ret = data;
        int i, val;

        mutex_lock(&data->update_lock);

        if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
                for (i = 0; i < t_num_temp; i++) {
                        val = i2c_smbus_read_word_swapped(client, temp_regs[i]);
                        if (val < 0) {
                                ret = ERR_PTR(val);
                                goto abort;
                        }
                        data->temp[i] = val;
                }
                data->last_updated = jiffies;
                data->valid = true;
        }
abort:
        mutex_unlock(&data->update_lock);
        return ret;
}

/* sysfs functions */

static ssize_t show_temp(struct device *dev, struct device_attribute *devattr,
                         char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct jc42_data *data = jc42_update_device(dev);
        if (IS_ERR(data))
                return PTR_ERR(data);
        return sprintf(buf, "%d\n",
                       jc42_temp_from_reg(data->temp[attr->index]));
}

static ssize_t show_temp_hyst(struct device *dev,
                              struct device_attribute *devattr, char *buf)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct jc42_data *data = jc42_update_device(dev);
        int temp, hyst;

        if (IS_ERR(data))
                return PTR_ERR(data);

        temp = jc42_temp_from_reg(data->temp[attr->index]);
        hyst = jc42_hysteresis[(data->config & JC42_CFG_HYST_MASK)
                               >> JC42_CFG_HYST_SHIFT];
        return sprintf(buf, "%d\n", temp - hyst);
}

static ssize_t set_temp(struct device *dev, struct device_attribute *devattr,
                        const char *buf, size_t count)
{
        struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
        struct jc42_data *data = dev_get_drvdata(dev);
        int err, ret = count;
        int nr = attr->index;
        long val;

        if (kstrtol(buf, 10, &val) < 0)
                return -EINVAL;
        mutex_lock(&data->update_lock);
        data->temp[nr] = jc42_temp_to_reg(val, data->extended);
        err = i2c_smbus_write_word_swapped(data->client, temp_regs[nr],
                                           data->temp[nr]);
        if (err < 0)
                ret = err;
        mutex_unlock(&data->update_lock);
        return ret;
}

/*
 * JC42.4 compliant chips only support four hysteresis values.
 * Pick best choice and go from there.
 */
static ssize_t set_temp_crit_hyst(struct device *dev,
                                  struct device_attribute *attr,
                                  const char *buf, size_t count)
{
        struct jc42_data *data = dev_get_drvdata(dev);
        long val;
        int diff, hyst;
        int err;
        int ret = count;

        if (kstrtol(buf, 10, &val) < 0)
                return -EINVAL;

        val = clamp_val(val, (data->extended ? JC42_TEMP_MIN_EXTENDED :
                              JC42_TEMP_MIN) - 6000, JC42_TEMP_MAX);
        diff = jc42_temp_from_reg(data->temp[t_crit]) - val;

        hyst = 0;
        if (diff > 0) {
                if (diff < 2250)
                        hyst = 1;       /* 1.5 degrees C */
                else if (diff < 4500)
                        hyst = 2;       /* 3.0 degrees C */
                else
                        hyst = 3;       /* 6.0 degrees C */
        }

        mutex_lock(&data->update_lock);
        data->config = (data->config & ~JC42_CFG_HYST_MASK)
          | (hyst << JC42_CFG_HYST_SHIFT);
        err = i2c_smbus_write_word_swapped(data->client, JC42_REG_CONFIG,
                                           data->config);
        if (err < 0)
                ret = err;
        mutex_unlock(&data->update_lock);
        return ret;
}

static ssize_t show_alarm(struct device *dev,
                          struct device_attribute *attr, char *buf)
{
        u16 bit = to_sensor_dev_attr(attr)->index;
        struct jc42_data *data = jc42_update_device(dev);
        u16 val;

        if (IS_ERR(data))
                return PTR_ERR(data);

        val = data->temp[t_input];
        if (bit != JC42_ALARM_CRIT_BIT && (data->config & JC42_CFG_CRIT_ONLY))
                val = 0;
        return sprintf(buf, "%u\n", (val >> bit) & 1);
}

static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL, t_input);
static SENSOR_DEVICE_ATTR(temp1_crit, S_IRUGO, show_temp, set_temp, t_crit);
static SENSOR_DEVICE_ATTR(temp1_min, S_IRUGO, show_temp, set_temp, t_min);
static SENSOR_DEVICE_ATTR(temp1_max, S_IRUGO, show_temp, set_temp, t_max);

static SENSOR_DEVICE_ATTR(temp1_crit_hyst, S_IRUGO, show_temp_hyst,
                          set_temp_crit_hyst, t_crit);
static SENSOR_DEVICE_ATTR(temp1_max_hyst, S_IRUGO, show_temp_hyst, NULL, t_max);

static SENSOR_DEVICE_ATTR(temp1_crit_alarm, S_IRUGO, show_alarm, NULL,
                          JC42_ALARM_CRIT_BIT);
static SENSOR_DEVICE_ATTR(temp1_min_alarm, S_IRUGO, show_alarm, NULL,
                          JC42_ALARM_MIN_BIT);
static SENSOR_DEVICE_ATTR(temp1_max_alarm, S_IRUGO, show_alarm, NULL,
                          JC42_ALARM_MAX_BIT);

static struct attribute *jc42_attributes[] = {
        &sensor_dev_attr_temp1_input.dev_attr.attr,
        &sensor_dev_attr_temp1_crit.dev_attr.attr,
        &sensor_dev_attr_temp1_min.dev_attr.attr,
        &sensor_dev_attr_temp1_max.dev_attr.attr,
        &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr,
        &sensor_dev_attr_temp1_max_hyst.dev_attr.attr,
        &sensor_dev_attr_temp1_crit_alarm.dev_attr.attr,
        &sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
        &sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
        NULL
};

static umode_t jc42_attribute_mode(struct kobject *kobj,
                                  struct attribute *attr, int index)
{
        struct device *dev = container_of(kobj, struct device, kobj);
        struct jc42_data *data = dev_get_drvdata(dev);
        unsigned int config = data->config;
        bool readonly;

        if (attr == &sensor_dev_attr_temp1_crit.dev_attr.attr)
                readonly = config & JC42_CFG_TCRIT_LOCK;
        else if (attr == &sensor_dev_attr_temp1_min.dev_attr.attr ||
                 attr == &sensor_dev_attr_temp1_max.dev_attr.attr)
                readonly = config & JC42_CFG_EVENT_LOCK;
        else if (attr == &sensor_dev_attr_temp1_crit_hyst.dev_attr.attr)
                readonly = config & (JC42_CFG_EVENT_LOCK | JC42_CFG_TCRIT_LOCK);
        else
                readonly = true;

        return S_IRUGO | (readonly ? 0 : S_IWUSR);
}

static const struct attribute_group jc42_group = {
        .attrs = jc42_attributes,
        .is_visible = jc42_attribute_mode,
};
__ATTRIBUTE_GROUPS(jc42);

/* Return 0 if detection is successful, -ENODEV otherwise */
static int jc42_detect(struct i2c_client *client, struct i2c_board_info *info)
{
        struct i2c_adapter *adapter = client->adapter;
        int i, config, cap, manid, devid;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                                     I2C_FUNC_SMBUS_WORD_DATA))
                return -ENODEV;

        cap = i2c_smbus_read_word_swapped(client, JC42_REG_CAP);
        config = i2c_smbus_read_word_swapped(client, JC42_REG_CONFIG);
        manid = i2c_smbus_read_word_swapped(client, JC42_REG_MANID);
        devid = i2c_smbus_read_word_swapped(client, JC42_REG_DEVICEID);

        if (cap < 0 || config < 0 || manid < 0 || devid < 0)
                return -ENODEV;

        if ((cap & 0xff00) || (config & 0xf800))
                return -ENODEV;

        for (i = 0; i < ARRAY_SIZE(jc42_chips); i++) {
                struct jc42_chips *chip = &jc42_chips[i];
                if (manid == chip->manid &&
                    (devid & chip->devid_mask) == chip->devid) {
                        strlcpy(info->type, "jc42", I2C_NAME_SIZE);
                        return 0;
                }
        }
        return -ENODEV;
}

static int jc42_probe(struct i2c_client *client, const struct i2c_device_id *id)
{
        struct device *dev = &client->dev;
        struct device *hwmon_dev;
        struct jc42_data *data;
        int config, cap;

        data = devm_kzalloc(dev, sizeof(struct jc42_data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->client = client;
        i2c_set_clientdata(client, data);
        mutex_init(&data->update_lock);

        cap = i2c_smbus_read_word_swapped(client, JC42_REG_CAP);
        if (cap < 0)
                return cap;

        data->extended = !!(cap & JC42_CAP_RANGE);

        config = i2c_smbus_read_word_swapped(client, JC42_REG_CONFIG);
        if (config < 0)
                return config;

        data->orig_config = config;
        if (config & JC42_CFG_SHUTDOWN) {
                config &= ~JC42_CFG_SHUTDOWN;
                i2c_smbus_write_word_swapped(client, JC42_REG_CONFIG, config);
        }
        data->config = config;

        hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
                                                           data,
                                                           jc42_groups);
        return PTR_ERR_OR_ZERO(hwmon_dev);
}

static int jc42_remove(struct i2c_client *client)
{
        struct jc42_data *data = i2c_get_clientdata(client);

        /* Restore original configuration except hysteresis */
        if ((data->config & ~JC42_CFG_HYST_MASK) !=
            (data->orig_config & ~JC42_CFG_HYST_MASK)) {
                int config;

                config = (data->orig_config & ~JC42_CFG_HYST_MASK)
                  | (data->config & JC42_CFG_HYST_MASK);
                i2c_smbus_write_word_swapped(client, JC42_REG_CONFIG, config);
        }
        return 0;
}

#ifdef CONFIG_PM

static int jc42_suspend(struct device *dev)
{
        struct jc42_data *data = dev_get_drvdata(dev);

        data->config |= JC42_CFG_SHUTDOWN;
        i2c_smbus_write_word_swapped(data->client, JC42_REG_CONFIG,
                                     data->config);
        return 0;
}

static int jc42_resume(struct device *dev)
{
        struct jc42_data *data = dev_get_drvdata(dev);

        data->config &= ~JC42_CFG_SHUTDOWN;
        i2c_smbus_write_word_swapped(data->client, JC42_REG_CONFIG,
                                     data->config);
        return 0;
}

static const struct dev_pm_ops jc42_dev_pm_ops = {
        .suspend = jc42_suspend,
        .resume = jc42_resume,
};

#define JC42_DEV_PM_OPS (&jc42_dev_pm_ops)
#else
#define JC42_DEV_PM_OPS NULL
#endif /* CONFIG_PM */

static const struct i2c_device_id jc42_id[] = {
        { "jc42", 0 },
        { }
};
MODULE_DEVICE_TABLE(i2c, jc42_id);

static struct i2c_driver jc42_driver = {
        .class          = I2C_CLASS_SPD,
        .driver = {
                .name   = "jc42",
                .pm = JC42_DEV_PM_OPS,
        },
        .probe          = jc42_probe,
        .remove         = jc42_remove,
        .id_table       = jc42_id,
        .detect         = jc42_detect,
        .address_list   = normal_i2c,
};

module_i2c_driver(jc42_driver);

MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
MODULE_DESCRIPTION("JC42 driver");
MODULE_LICENSE("GPL");