// SPDX-License-Identifier: GPL-2.0
/*
 * I2C multiplexer
 *
 * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
 * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
 *
 * This module supports the PCA954x and PCA984x series of I2C multiplexer/switch
 * chips made by NXP Semiconductors.
 * This includes the:
 *       PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547,
 *       PCA9548, PCA9846, PCA9847, PCA9848 and PCA9849.
 *
 * These chips are all controlled via the I2C bus itself, and all have a
 * single 8-bit register. The upstream "parent" bus fans out to two,
 * four, or eight downstream busses or channels; which of these
 * are selected is determined by the chip type and register contents. A
 * mux can select only one sub-bus at a time; a switch can select any
 * combination simultaneously.
 *
 * Based on:
 *      pca954x.c from Kumar Gala <galak@kernel.crashing.org>
 * Copyright (C) 2006
 *
 * Based on:
 *      pca954x.c from Ken Harrenstien
 * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
 *
 * Based on:
 *      i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
 * and
 *      pca9540.c from Jean Delvare <jdelvare@suse.de>.
 */

#include <linux/device.h>
#include <linux/delay.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/i2c-mux.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/pm.h>
#include <linux/property.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <dt-bindings/mux/mux.h>

#define PCA954X_MAX_NCHANS 8

#define PCA954X_IRQ_OFFSET 4

enum pca_type {
        pca_9540,
        pca_9542,
        pca_9543,
        pca_9544,
        pca_9545,
        pca_9546,
        pca_9547,
        pca_9548,
        pca_9846,
        pca_9847,
        pca_9848,
        pca_9849,
};

struct chip_desc {
        u8 nchans;
        u8 enable;      /* used for muxes only */
        u8 has_irq;
        enum muxtype {
                pca954x_ismux = 0,
                pca954x_isswi
        } muxtype;
        struct i2c_device_identity id;
};

struct pca954x {
        const struct chip_desc *chip;

        u8 last_chan;           /* last register value */
        /* MUX_IDLE_AS_IS, MUX_IDLE_DISCONNECT or >= 0 for channel */
        s32 idle_state;

        struct i2c_client *client;

        struct irq_domain *irq;
        unsigned int irq_mask;
        raw_spinlock_t lock;
};

/* Provide specs for the PCA954x types we know about */
static const struct chip_desc chips[] = {
        [pca_9540] = {
                .nchans = 2,
                .enable = 0x4,
                .muxtype = pca954x_ismux,
                .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
        },
        [pca_9542] = {
                .nchans = 2,
                .enable = 0x4,
                .has_irq = 1,
                .muxtype = pca954x_ismux,
                .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
        },
        [pca_9543] = {
                .nchans = 2,
                .has_irq = 1,
                .muxtype = pca954x_isswi,
                .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
        },
        [pca_9544] = {
                .nchans = 4,
                .enable = 0x4,
                .has_irq = 1,
                .muxtype = pca954x_ismux,
                .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
        },
        [pca_9545] = {
                .nchans = 4,
                .has_irq = 1,
                .muxtype = pca954x_isswi,
                .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
        },
        [pca_9546] = {
                .nchans = 4,
                .muxtype = pca954x_isswi,
                .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
        },
        [pca_9547] = {
                .nchans = 8,
                .enable = 0x8,
                .muxtype = pca954x_ismux,
                .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
        },
        [pca_9548] = {
                .nchans = 8,
                .muxtype = pca954x_isswi,
                .id = { .manufacturer_id = I2C_DEVICE_ID_NONE },
        },
        [pca_9846] = {
                .nchans = 4,
                .muxtype = pca954x_isswi,
                .id = {
                        .manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
                        .part_id = 0x10b,
                },
        },
        [pca_9847] = {
                .nchans = 8,
                .enable = 0x8,
                .muxtype = pca954x_ismux,
                .id = {
                        .manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
                        .part_id = 0x108,
                },
        },
        [pca_9848] = {
                .nchans = 8,
                .muxtype = pca954x_isswi,
                .id = {
                        .manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
                        .part_id = 0x10a,
                },
        },
        [pca_9849] = {
                .nchans = 4,
                .enable = 0x4,
                .muxtype = pca954x_ismux,
                .id = {
                        .manufacturer_id = I2C_DEVICE_ID_NXP_SEMICONDUCTORS,
                        .part_id = 0x109,
                },
        },
};

static const struct i2c_device_id pca954x_id[] = {
        { "pca9540", pca_9540 },
        { "pca9542", pca_9542 },
        { "pca9543", pca_9543 },
        { "pca9544", pca_9544 },
        { "pca9545", pca_9545 },
        { "pca9546", pca_9546 },
        { "pca9547", pca_9547 },
        { "pca9548", pca_9548 },
        { "pca9846", pca_9846 },
        { "pca9847", pca_9847 },
        { "pca9848", pca_9848 },
        { "pca9849", pca_9849 },
        { }
};
MODULE_DEVICE_TABLE(i2c, pca954x_id);

static const struct of_device_id pca954x_of_match[] = {
        { .compatible = "nxp,pca9540", .data = &chips[pca_9540] },
        { .compatible = "nxp,pca9542", .data = &chips[pca_9542] },
        { .compatible = "nxp,pca9543", .data = &chips[pca_9543] },
        { .compatible = "nxp,pca9544", .data = &chips[pca_9544] },
        { .compatible = "nxp,pca9545", .data = &chips[pca_9545] },
        { .compatible = "nxp,pca9546", .data = &chips[pca_9546] },
        { .compatible = "nxp,pca9547", .data = &chips[pca_9547] },
        { .compatible = "nxp,pca9548", .data = &chips[pca_9548] },
        { .compatible = "nxp,pca9846", .data = &chips[pca_9846] },
        { .compatible = "nxp,pca9847", .data = &chips[pca_9847] },
        { .compatible = "nxp,pca9848", .data = &chips[pca_9848] },
        { .compatible = "nxp,pca9849", .data = &chips[pca_9849] },
        {}
};
MODULE_DEVICE_TABLE(of, pca954x_of_match);

/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
   for this as they will try to lock adapter a second time */
static int pca954x_reg_write(struct i2c_adapter *adap,
                             struct i2c_client *client, u8 val)
{
        union i2c_smbus_data dummy;

        return __i2c_smbus_xfer(adap, client->addr, client->flags,
                                I2C_SMBUS_WRITE, val,
                                I2C_SMBUS_BYTE, &dummy);
}

static u8 pca954x_regval(struct pca954x *data, u8 chan)
{
        /* We make switches look like muxes, not sure how to be smarter. */
        if (data->chip->muxtype == pca954x_ismux)
                return chan | data->chip->enable;
        else
                return 1 << chan;
}

static int pca954x_select_chan(struct i2c_mux_core *muxc, u32 chan)
{
        struct pca954x *data = i2c_mux_priv(muxc);
        struct i2c_client *client = data->client;
        u8 regval;
        int ret = 0;

        regval = pca954x_regval(data, chan);
        /* Only select the channel if its different from the last channel */
        if (data->last_chan != regval) {
                ret = pca954x_reg_write(muxc->parent, client, regval);
                data->last_chan = ret < 0 ? 0 : regval;
        }

        return ret;
}

static int pca954x_deselect_mux(struct i2c_mux_core *muxc, u32 chan)
{
        struct pca954x *data = i2c_mux_priv(muxc);
        struct i2c_client *client = data->client;
        s32 idle_state;

        idle_state = READ_ONCE(data->idle_state);
        if (idle_state >= 0)
                /* Set the mux back to a predetermined channel */
                return pca954x_select_chan(muxc, idle_state);

        if (idle_state == MUX_IDLE_DISCONNECT) {
                /* Deselect active channel */
                data->last_chan = 0;
                return pca954x_reg_write(muxc->parent, client,
                                         data->last_chan);
        }

        /* otherwise leave as-is */

        return 0;
}

static ssize_t idle_state_show(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct i2c_mux_core *muxc = i2c_get_clientdata(client);
        struct pca954x *data = i2c_mux_priv(muxc);

        return sprintf(buf, "%d\n", READ_ONCE(data->idle_state));
}

static ssize_t idle_state_store(struct device *dev,
                                struct device_attribute *attr,
                                const char *buf, size_t count)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct i2c_mux_core *muxc = i2c_get_clientdata(client);
        struct pca954x *data = i2c_mux_priv(muxc);
        int val;
        int ret;

        ret = kstrtoint(buf, 0, &val);
        if (ret < 0)
                return ret;

        if (val != MUX_IDLE_AS_IS && val != MUX_IDLE_DISCONNECT &&
            (val < 0 || val >= data->chip->nchans))
                return -EINVAL;

        i2c_lock_bus(muxc->parent, I2C_LOCK_SEGMENT);

        WRITE_ONCE(data->idle_state, val);
        /*
         * Set the mux into a state consistent with the new
         * idle_state.
         */
        if (data->last_chan || val != MUX_IDLE_DISCONNECT)
                ret = pca954x_deselect_mux(muxc, 0);

        i2c_unlock_bus(muxc->parent, I2C_LOCK_SEGMENT);

        return ret < 0 ? ret : count;
}

static DEVICE_ATTR_RW(idle_state);

static irqreturn_t pca954x_irq_handler(int irq, void *dev_id)
{
        struct pca954x *data = dev_id;
        unsigned long pending;
        int ret, i;

        ret = i2c_smbus_read_byte(data->client);
        if (ret < 0)
                return IRQ_NONE;

        pending = (ret >> PCA954X_IRQ_OFFSET) & (BIT(data->chip->nchans) - 1);
        for_each_set_bit(i, &pending, data->chip->nchans)
                handle_nested_irq(irq_linear_revmap(data->irq, i));

        return IRQ_RETVAL(pending);
}

static int pca954x_irq_set_type(struct irq_data *idata, unsigned int type)
{
        if ((type & IRQ_TYPE_SENSE_MASK) != IRQ_TYPE_LEVEL_LOW)
                return -EINVAL;
        return 0;
}

static struct irq_chip pca954x_irq_chip = {
        .name = "i2c-mux-pca954x",
        .irq_set_type = pca954x_irq_set_type,
};

static int pca954x_irq_setup(struct i2c_mux_core *muxc)
{
        struct pca954x *data = i2c_mux_priv(muxc);
        struct i2c_client *client = data->client;
        int c, irq;

        if (!data->chip->has_irq || client->irq <= 0)
                return 0;

        raw_spin_lock_init(&data->lock);

        data->irq = irq_domain_add_linear(client->dev.of_node,
                                          data->chip->nchans,
                                          &irq_domain_simple_ops, data);
        if (!data->irq)
                return -ENODEV;

        for (c = 0; c < data->chip->nchans; c++) {
                irq = irq_create_mapping(data->irq, c);
                if (!irq) {
                        dev_err(&client->dev, "failed irq create map\n");
                        return -EINVAL;
                }
                irq_set_chip_data(irq, data);
                irq_set_chip_and_handler(irq, &pca954x_irq_chip,
                        handle_simple_irq);
        }

        return 0;
}

static void pca954x_cleanup(struct i2c_mux_core *muxc)
{
        struct pca954x *data = i2c_mux_priv(muxc);
        int c, irq;

        if (data->irq) {
                for (c = 0; c < data->chip->nchans; c++) {
                        irq = irq_find_mapping(data->irq, c);
                        irq_dispose_mapping(irq);
                }
                irq_domain_remove(data->irq);
        }
        i2c_mux_del_adapters(muxc);
}

static int pca954x_init(struct i2c_client *client, struct pca954x *data)
{
        int ret;

        if (data->idle_state >= 0)
                data->last_chan = pca954x_regval(data, data->idle_state);
        else
                data->last_chan = 0; /* Disconnect multiplexer */

        ret = i2c_smbus_write_byte(client, data->last_chan);
        if (ret < 0)
                data->last_chan = 0;

        return ret;
}

/*
 * I2C init/probing/exit functions
 */
static int pca954x_probe(struct i2c_client *client,
                         const struct i2c_device_id *id)
{
        struct i2c_adapter *adap = client->adapter;
        struct device *dev = &client->dev;
        struct gpio_desc *gpio;
        struct i2c_mux_core *muxc;
        struct pca954x *data;
        int num;
        int ret;

        if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
                return -ENODEV;

        muxc = i2c_mux_alloc(adap, dev, PCA954X_MAX_NCHANS, sizeof(*data), 0,
                             pca954x_select_chan, pca954x_deselect_mux);
        if (!muxc)
                return -ENOMEM;
        data = i2c_mux_priv(muxc);

        i2c_set_clientdata(client, muxc);
        data->client = client;

        /* Reset the mux if a reset GPIO is specified. */
        gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
        if (IS_ERR(gpio))
                return PTR_ERR(gpio);
        if (gpio) {
                udelay(1);
                gpiod_set_value_cansleep(gpio, 0);
                /* Give the chip some time to recover. */
                udelay(1);
        }

        data->chip = device_get_match_data(dev);
        if (!data->chip)
                data->chip = &chips[id->driver_data];

        if (data->chip->id.manufacturer_id != I2C_DEVICE_ID_NONE) {
                struct i2c_device_identity id;

                ret = i2c_get_device_id(client, &id);
                if (ret && ret != -EOPNOTSUPP)
                        return ret;

                if (!ret &&
                    (id.manufacturer_id != data->chip->id.manufacturer_id ||
                     id.part_id != data->chip->id.part_id)) {
                        dev_warn(dev, "unexpected device id %03x-%03x-%x\n",
                                 id.manufacturer_id, id.part_id,
                                 id.die_revision);
                        return -ENODEV;
                }
        }

        data->idle_state = MUX_IDLE_AS_IS;
        if (device_property_read_u32(dev, "idle-state", &data->idle_state)) {
                if (device_property_read_bool(dev, "i2c-mux-idle-disconnect"))
                        data->idle_state = MUX_IDLE_DISCONNECT;
        }

        /*
         * Write the mux register at addr to verify
         * that the mux is in fact present. This also
         * initializes the mux to a channel
         * or disconnected state.
         */
        ret = pca954x_init(client, data);
        if (ret < 0) {
                dev_warn(dev, "probe failed\n");
                return -ENODEV;
        }

        ret = pca954x_irq_setup(muxc);
        if (ret)
                goto fail_cleanup;

        /* Now create an adapter for each channel */
        for (num = 0; num < data->chip->nchans; num++) {
                ret = i2c_mux_add_adapter(muxc, 0, num, 0);
                if (ret)
                        goto fail_cleanup;
        }

        if (data->irq) {
                ret = devm_request_threaded_irq(dev, data->client->irq,
                                                NULL, pca954x_irq_handler,
                                                IRQF_ONESHOT | IRQF_SHARED,
                                                "pca954x", data);
                if (ret)
                        goto fail_cleanup;
        }

        /*
         * The attr probably isn't going to be needed in most cases,
         * so don't fail completely on error.
         */
        device_create_file(dev, &dev_attr_idle_state);

        dev_info(dev, "registered %d multiplexed busses for I2C %s %s\n",
                 num, data->chip->muxtype == pca954x_ismux
                                ? "mux" : "switch", client->name);

        return 0;

fail_cleanup:
        pca954x_cleanup(muxc);
        return ret;
}

static int pca954x_remove(struct i2c_client *client)
{
        struct i2c_mux_core *muxc = i2c_get_clientdata(client);

        device_remove_file(&client->dev, &dev_attr_idle_state);

        pca954x_cleanup(muxc);
        return 0;
}

#ifdef CONFIG_PM_SLEEP
static int pca954x_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct i2c_mux_core *muxc = i2c_get_clientdata(client);
        struct pca954x *data = i2c_mux_priv(muxc);
        int ret;

        ret = pca954x_init(client, data);
        if (ret < 0)
                dev_err(&client->dev, "failed to verify mux presence\n");

        return ret;
}
#endif

static SIMPLE_DEV_PM_OPS(pca954x_pm, NULL, pca954x_resume);

static struct i2c_driver pca954x_driver = {
        .driver         = {
                .name   = "pca954x",
                .pm     = &pca954x_pm,
                .of_match_table = pca954x_of_match,
        },
        .probe          = pca954x_probe,
        .remove         = pca954x_remove,
        .id_table       = pca954x_id,
};

module_i2c_driver(pca954x_driver);

MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
MODULE_LICENSE("GPL v2");