// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for SBS compliant Smart Battery System Managers
 *
 * The device communicates via i2c at address 0x0a and multiplexes access to up
 * to four smart batteries at address 0x0b.
 *
 * Via sysfs interface the online state and charge type are presented.
 *
 * Datasheet SBSM:    http://sbs-forum.org/specs/sbsm100b.pdf
 * Datasheet LTC1760: http://cds.linear.com/docs/en/datasheet/1760fb.pdf
 *
 * Karl-Heinz Schneider <karl-heinz@schneider-inet.de>
 */

#include <linux/gpio/driver.h>
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/power_supply.h>
#include <linux/property.h>

#define SBSM_MAX_BATS  4
#define SBSM_RETRY_CNT 3

/* registers addresses */
#define SBSM_CMD_BATSYSSTATE     0x01
#define SBSM_CMD_BATSYSSTATECONT 0x02
#define SBSM_CMD_BATSYSINFO      0x04
#define SBSM_CMD_LTC             0x3c

#define SBSM_MASK_BAT_SUPPORTED  GENMASK(3, 0)
#define SBSM_MASK_CHARGE_BAT     GENMASK(7, 4)
#define SBSM_BIT_AC_PRESENT      BIT(0)
#define SBSM_BIT_TURBO           BIT(7)

#define SBSM_SMB_BAT_OFFSET      11
struct sbsm_data {
        struct i2c_client *client;
        struct i2c_mux_core *muxc;

        struct power_supply *psy;

        u8 cur_chan;          /* currently selected channel */
        struct gpio_chip chip;
        bool is_ltc1760;      /* special capabilities */

        unsigned int supported_bats;
        unsigned int last_state;
        unsigned int last_state_cont;
};

static enum power_supply_property sbsm_props[] = {
        POWER_SUPPLY_PROP_ONLINE,
        POWER_SUPPLY_PROP_CHARGE_TYPE,
};

static int sbsm_read_word(struct i2c_client *client, u8 address)
{
        int reg, retries;

        for (retries = SBSM_RETRY_CNT; retries > 0; retries--) {
                reg = i2c_smbus_read_word_data(client, address);
                if (reg >= 0)
                        break;
        }

        if (reg < 0) {
                dev_err(&client->dev, "failed to read register 0x%02x\n",
                        address);
        }

        return reg;
}

static int sbsm_write_word(struct i2c_client *client, u8 address, u16 word)
{
        int ret, retries;

        for (retries = SBSM_RETRY_CNT; retries > 0; retries--) {
                ret = i2c_smbus_write_word_data(client, address, word);
                if (ret >= 0)
                        break;
        }
        if (ret < 0)
                dev_err(&client->dev, "failed to write to register 0x%02x\n",
                        address);

        return ret;
}

static int sbsm_get_property(struct power_supply *psy,
                             enum power_supply_property psp,
                             union power_supply_propval *val)
{
        struct sbsm_data *data = power_supply_get_drvdata(psy);
        int regval = 0;

        switch (psp) {
        case POWER_SUPPLY_PROP_ONLINE:
                regval = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATECONT);
                if (regval < 0)
                        return regval;
                val->intval = !!(regval & SBSM_BIT_AC_PRESENT);
                break;

        case POWER_SUPPLY_PROP_CHARGE_TYPE:
                regval = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATE);
                if (regval < 0)
                        return regval;

                if ((regval & SBSM_MASK_CHARGE_BAT) == 0) {
                        val->intval = POWER_SUPPLY_CHARGE_TYPE_NONE;
                        return 0;
                }
                val->intval = POWER_SUPPLY_CHARGE_TYPE_TRICKLE;

                if (data->is_ltc1760) {
                        /* charge mode fast if turbo is active */
                        regval = sbsm_read_word(data->client, SBSM_CMD_LTC);
                        if (regval < 0)
                                return regval;
                        else if (regval & SBSM_BIT_TURBO)
                                val->intval = POWER_SUPPLY_CHARGE_TYPE_FAST;
                }
                break;

        default:
                return -EINVAL;
        }

        return 0;
}

static int sbsm_prop_is_writeable(struct power_supply *psy,
                                  enum power_supply_property psp)
{
        struct sbsm_data *data = power_supply_get_drvdata(psy);

        return (psp == POWER_SUPPLY_PROP_CHARGE_TYPE) && data->is_ltc1760;
}

static int sbsm_set_property(struct power_supply *psy,
                             enum power_supply_property psp,
                             const union power_supply_propval *val)
{
        struct sbsm_data *data = power_supply_get_drvdata(psy);
        int ret = -EINVAL;
        u16 regval;

        switch (psp) {
        case POWER_SUPPLY_PROP_CHARGE_TYPE:
                /* write 1 to TURBO if type fast is given */
                if (!data->is_ltc1760)
                        break;
                regval = val->intval ==
                         POWER_SUPPLY_CHARGE_TYPE_FAST ? SBSM_BIT_TURBO : 0;
                ret = sbsm_write_word(data->client, SBSM_CMD_LTC, regval);
                break;

        default:
                break;
        }

        return ret;
}

/*
 * Switch to battery
 * Parameter chan is directly the content of SMB_BAT* nibble
 */
static int sbsm_select(struct i2c_mux_core *muxc, u32 chan)
{
        struct sbsm_data *data = i2c_mux_priv(muxc);
        struct device *dev = &data->client->dev;
        int ret = 0;
        u16 reg;

        if (data->cur_chan == chan)
                return ret;

        /* chan goes from 1 ... 4 */
        reg = BIT(SBSM_SMB_BAT_OFFSET + chan);
        ret = sbsm_write_word(data->client, SBSM_CMD_BATSYSSTATE, reg);
        if (ret)
                dev_err(dev, "Failed to select channel %i\n", chan);
        else
                data->cur_chan = chan;

        return ret;
}

static int sbsm_gpio_get_value(struct gpio_chip *gc, unsigned int off)
{
        struct sbsm_data *data = gpiochip_get_data(gc);
        int ret;

        ret = sbsm_read_word(data->client, SBSM_CMD_BATSYSSTATE);
        if (ret < 0)
                return ret;

        return ret & BIT(off);
}

/*
 * This needs to be defined or the GPIO lib fails to register the pin.
 * But the 'gpio' is always an input.
 */
static int sbsm_gpio_direction_input(struct gpio_chip *gc, unsigned int off)
{
        return 0;
}

static int sbsm_do_alert(struct device *dev, void *d)
{
        struct i2c_client *client = i2c_verify_client(dev);
        struct i2c_driver *driver;

        if (!client || client->addr != 0x0b)
                return 0;

        device_lock(dev);
        if (client->dev.driver) {
                driver = to_i2c_driver(client->dev.driver);
                if (driver->alert)
                        driver->alert(client, I2C_PROTOCOL_SMBUS_ALERT, 0);
                else
                        dev_warn(&client->dev, "no driver alert()!\n");
        } else {
                dev_dbg(&client->dev, "alert with no driver\n");
        }
        device_unlock(dev);

        return -EBUSY;
}

static void sbsm_alert(struct i2c_client *client, enum i2c_alert_protocol prot,
                       unsigned int d)
{
        struct sbsm_data *sbsm = i2c_get_clientdata(client);

        int ret, i, irq_bat = 0, state = 0;

        ret = sbsm_read_word(sbsm->client, SBSM_CMD_BATSYSSTATE);
        if (ret >= 0) {
                irq_bat = ret ^ sbsm->last_state;
                sbsm->last_state = ret;
                state = ret;
        }

        ret = sbsm_read_word(sbsm->client, SBSM_CMD_BATSYSSTATECONT);
        if ((ret >= 0) &&
            ((ret ^ sbsm->last_state_cont) & SBSM_BIT_AC_PRESENT)) {
                irq_bat |= sbsm->supported_bats & state;
                power_supply_changed(sbsm->psy);
        }
        sbsm->last_state_cont = ret;

        for (i = 0; i < SBSM_MAX_BATS; i++) {
                if (irq_bat & BIT(i)) {
                        device_for_each_child(&sbsm->muxc->adapter[i]->dev,
                                              NULL, sbsm_do_alert);
                }
        }
}

static int sbsm_gpio_setup(struct sbsm_data *data)
{
        struct gpio_chip *gc = &data->chip;
        struct i2c_client *client = data->client;
        struct device *dev = &client->dev;
        int ret;

        if (!device_property_present(dev, "gpio-controller"))
                return 0;

        ret  = sbsm_read_word(client, SBSM_CMD_BATSYSSTATE);
        if (ret < 0)
                return ret;
        data->last_state = ret;

        ret  = sbsm_read_word(client, SBSM_CMD_BATSYSSTATECONT);
        if (ret < 0)
                return ret;
        data->last_state_cont = ret;

        gc->get = sbsm_gpio_get_value;
        gc->direction_input  = sbsm_gpio_direction_input;
        gc->can_sleep = true;
        gc->base = -1;
        gc->ngpio = SBSM_MAX_BATS;
        gc->label = client->name;
        gc->parent = dev;
        gc->owner = THIS_MODULE;

        ret = devm_gpiochip_add_data(dev, gc, data);
        if (ret)
                return dev_err_probe(dev, ret, "devm_gpiochip_add_data failed\n");

        return ret;
}

static const struct power_supply_desc sbsm_default_psy_desc = {
        .type = POWER_SUPPLY_TYPE_MAINS,
        .properties = sbsm_props,
        .num_properties = ARRAY_SIZE(sbsm_props),
        .get_property = &sbsm_get_property,
        .set_property = &sbsm_set_property,
        .property_is_writeable = &sbsm_prop_is_writeable,
};

static void sbsm_del_mux_adapter(void *data)
{
        struct sbsm_data *sbsm = data;
        i2c_mux_del_adapters(sbsm->muxc);
}

static int sbsm_probe(struct i2c_client *client)
{
        const struct i2c_device_id *id = i2c_client_get_device_id(client);
        struct i2c_adapter *adapter = client->adapter;
        struct sbsm_data *data;
        struct device *dev = &client->dev;
        struct power_supply_desc *psy_desc;
        struct power_supply_config psy_cfg = {};
        int ret = 0, i;

        /* Device listens only at address 0x0a */
        if (client->addr != 0x0a)
                return -EINVAL;

        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
                return -EPFNOSUPPORT;

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

        i2c_set_clientdata(client, data);

        data->client = client;
        data->is_ltc1760 = !!strstr(id->name, "ltc1760");

        ret  = sbsm_read_word(client, SBSM_CMD_BATSYSINFO);
        if (ret < 0)
                return ret;
        data->supported_bats = ret & SBSM_MASK_BAT_SUPPORTED;
        data->muxc = i2c_mux_alloc(adapter, dev, SBSM_MAX_BATS, 0,
                                   I2C_MUX_LOCKED, &sbsm_select, NULL);
        if (!data->muxc)
                return -ENOMEM;
        data->muxc->priv = data;

        ret = devm_add_action_or_reset(dev, sbsm_del_mux_adapter, data);
        if (ret)
                return ret;

        /* register muxed i2c channels. One for each supported battery */
        for (i = 0; i < SBSM_MAX_BATS; ++i) {
                if (data->supported_bats & BIT(i)) {
                        ret = i2c_mux_add_adapter(data->muxc, 0, i + 1);
                        if (ret)
                                break;
                }
        }
        if (ret)
                return dev_err_probe(dev, ret, "failed to register i2c mux channel %d\n", i + 1);

        psy_desc = devm_kmemdup(dev, &sbsm_default_psy_desc, sizeof(*psy_desc), GFP_KERNEL);
        if (!psy_desc)
                return -ENOMEM;

        psy_desc->name = devm_kasprintf(dev, GFP_KERNEL, "sbsm-%s", dev_name(&client->dev));
        if (!psy_desc->name)
                return -ENOMEM;

        ret = sbsm_gpio_setup(data);
        if (ret < 0)
                return ret;

        psy_cfg.drv_data = data;
        psy_cfg.fwnode = dev_fwnode(dev);
        data->psy = devm_power_supply_register(dev, psy_desc, &psy_cfg);
        if (IS_ERR(data->psy))
                return dev_err_probe(dev, PTR_ERR(data->psy),
                                     "failed to register power supply %s\n", psy_desc->name);

        return 0;
}

static const struct i2c_device_id sbsm_ids[] = {
        { "sbs-manager" },
        { "ltc1760" },
        { }
};
MODULE_DEVICE_TABLE(i2c, sbsm_ids);

#ifdef CONFIG_OF
static const struct of_device_id sbsm_dt_ids[] = {
        { .compatible = "sbs,sbs-manager" },
        { .compatible = "lltc,ltc1760" },
        { }
};
MODULE_DEVICE_TABLE(of, sbsm_dt_ids);
#endif

static struct i2c_driver sbsm_driver = {
        .driver = {
                .name = "sbsm",
                .of_match_table = of_match_ptr(sbsm_dt_ids),
        },
        .probe          = sbsm_probe,
        .alert          = sbsm_alert,
        .id_table       = sbsm_ids
};
module_i2c_driver(sbsm_driver);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Karl-Heinz Schneider <karl-heinz@schneider-inet.de>");
MODULE_DESCRIPTION("SBSM Smart Battery System Manager");