// SPDX-License-Identifier: GPL-2.0-only
/*
 *  TDA9950 Consumer Electronics Control driver
 *
 * The NXP TDA9950 implements the HDMI Consumer Electronics Control
 * interface.  The host interface is similar to a mailbox: the data
 * registers starting at REG_CDR0 are written to send a command to the
 * internal CPU, and replies are read from these registers.
 *
 * As the data registers represent a mailbox, they must be accessed
 * as a single I2C transaction.  See the TDA9950 data sheet for details.
 */
#include <linux/delay.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/platform_data/tda9950.h>
#include <linux/slab.h>
#include <drm/drm_edid.h>
#include <media/cec.h>
#include <media/cec-notifier.h>

enum {
        REG_CSR = 0x00,
        CSR_BUSY = BIT(7),
        CSR_INT  = BIT(6),
        CSR_ERR  = BIT(5),

        REG_CER = 0x01,

        REG_CVR = 0x02,

        REG_CCR = 0x03,
        CCR_RESET = BIT(7),
        CCR_ON    = BIT(6),

        REG_ACKH = 0x04,
        REG_ACKL = 0x05,

        REG_CCONR = 0x06,
        CCONR_ENABLE_ERROR = BIT(4),
        CCONR_RETRY_MASK = 7,

        REG_CDR0 = 0x07,

        CDR1_REQ = 0x00,
        CDR1_CNF = 0x01,
        CDR1_IND = 0x81,
        CDR1_ERR = 0x82,
        CDR1_IER = 0x83,

        CDR2_CNF_SUCCESS    = 0x00,
        CDR2_CNF_OFF_STATE  = 0x80,
        CDR2_CNF_BAD_REQ    = 0x81,
        CDR2_CNF_CEC_ACCESS = 0x82,
        CDR2_CNF_ARB_ERROR  = 0x83,
        CDR2_CNF_BAD_TIMING = 0x84,
        CDR2_CNF_NACK_ADDR  = 0x85,
        CDR2_CNF_NACK_DATA  = 0x86,
};

struct tda9950_priv {
        struct i2c_client *client;
        struct device *hdmi;
        struct cec_adapter *adap;
        struct tda9950_glue *glue;
        u16 addresses;
        struct cec_msg rx_msg;
        struct cec_notifier *notify;
        bool open;
};

static int tda9950_write_range(struct i2c_client *client, u8 addr, u8 *p, int cnt)
{
        struct i2c_msg msg;
        u8 buf[CEC_MAX_MSG_SIZE + 3];
        int ret;

        if (WARN_ON(cnt > sizeof(buf) - 1))
                return -EINVAL;

        buf[0] = addr;
        memcpy(buf + 1, p, cnt);

        msg.addr = client->addr;
        msg.flags = 0;
        msg.len = cnt + 1;
        msg.buf = buf;

        dev_dbg(&client->dev, "wr 0x%02x: %*ph\n", addr, cnt, p);

        ret = i2c_transfer(client->adapter, &msg, 1);
        if (ret < 0)
                dev_err(&client->dev, "Error %d writing to cec:0x%x\n", ret, addr);
        return ret < 0 ? ret : 0;
}

static void tda9950_write(struct i2c_client *client, u8 addr, u8 val)
{
        tda9950_write_range(client, addr, &val, 1);
}

static int tda9950_read_range(struct i2c_client *client, u8 addr, u8 *p, int cnt)
{
        struct i2c_msg msg[2];
        int ret;

        msg[0].addr = client->addr;
        msg[0].flags = 0;
        msg[0].len = 1;
        msg[0].buf = &addr;
        msg[1].addr = client->addr;
        msg[1].flags = I2C_M_RD;
        msg[1].len = cnt;
        msg[1].buf = p;

        ret = i2c_transfer(client->adapter, msg, 2);
        if (ret < 0)
                dev_err(&client->dev, "Error %d reading from cec:0x%x\n", ret, addr);

        dev_dbg(&client->dev, "rd 0x%02x: %*ph\n", addr, cnt, p);

        return ret;
}

static u8 tda9950_read(struct i2c_client *client, u8 addr)
{
        int ret;
        u8 val;

        ret = tda9950_read_range(client, addr, &val, 1);
        if (ret < 0)
                val = 0;

        return val;
}

static irqreturn_t tda9950_irq(int irq, void *data)
{
        struct tda9950_priv *priv = data;
        unsigned int tx_status;
        u8 csr, cconr, buf[19];
        u8 arb_lost_cnt, nack_cnt, err_cnt;

        if (!priv->open)
                return IRQ_NONE;

        csr = tda9950_read(priv->client, REG_CSR);
        if (!(csr & CSR_INT))
                return IRQ_NONE;

        cconr = tda9950_read(priv->client, REG_CCONR) & CCONR_RETRY_MASK;

        tda9950_read_range(priv->client, REG_CDR0, buf, sizeof(buf));

        /*
         * This should never happen: the data sheet says that there will
         * always be a valid message if the interrupt line is asserted.
         */
        if (buf[0] == 0) {
                dev_warn(&priv->client->dev, "interrupt pending, but no message?\n");
                return IRQ_NONE;
        }

        switch (buf[1]) {
        case CDR1_CNF: /* transmit result */
                arb_lost_cnt = nack_cnt = err_cnt = 0;
                switch (buf[2]) {
                case CDR2_CNF_SUCCESS:
                        tx_status = CEC_TX_STATUS_OK;
                        break;

                case CDR2_CNF_ARB_ERROR:
                        tx_status = CEC_TX_STATUS_ARB_LOST;
                        arb_lost_cnt = cconr;
                        break;

                case CDR2_CNF_NACK_ADDR:
                        tx_status = CEC_TX_STATUS_NACK;
                        nack_cnt = cconr;
                        break;

                default: /* some other error, refer to TDA9950 docs */
                        dev_err(&priv->client->dev, "CNF reply error 0x%02x\n",
                                buf[2]);
                        tx_status = CEC_TX_STATUS_ERROR;
                        err_cnt = cconr;
                        break;
                }
                /* TDA9950 executes all retries for us */
                if (tx_status != CEC_TX_STATUS_OK)
                        tx_status |= CEC_TX_STATUS_MAX_RETRIES;
                cec_transmit_done(priv->adap, tx_status, arb_lost_cnt,
                                  nack_cnt, 0, err_cnt);
                break;

        case CDR1_IND:
                priv->rx_msg.len = buf[0] - 2;
                if (priv->rx_msg.len > CEC_MAX_MSG_SIZE)
                        priv->rx_msg.len = CEC_MAX_MSG_SIZE;

                memcpy(priv->rx_msg.msg, buf + 2, priv->rx_msg.len);
                cec_received_msg(priv->adap, &priv->rx_msg);
                break;

        default: /* unknown */
                dev_err(&priv->client->dev, "unknown service id 0x%02x\n",
                        buf[1]);
                break;
        }

        return IRQ_HANDLED;
}

static int tda9950_cec_transmit(struct cec_adapter *adap, u8 attempts,
                                u32 signal_free_time, struct cec_msg *msg)
{
        struct tda9950_priv *priv = adap->priv;
        u8 buf[CEC_MAX_MSG_SIZE + 2];

        buf[0] = 2 + msg->len;
        buf[1] = CDR1_REQ;
        memcpy(buf + 2, msg->msg, msg->len);

        if (attempts > 5)
                attempts = 5;

        tda9950_write(priv->client, REG_CCONR, attempts);

        return tda9950_write_range(priv->client, REG_CDR0, buf, 2 + msg->len);
}

static int tda9950_cec_adap_log_addr(struct cec_adapter *adap, u8 addr)
{
        struct tda9950_priv *priv = adap->priv;
        u16 addresses;
        u8 buf[2];

        if (addr == CEC_LOG_ADDR_INVALID)
                addresses = priv->addresses = 0;
        else
                addresses = priv->addresses |= BIT(addr);

        /* TDA9950 doesn't want address 15 set */
        addresses &= 0x7fff;
        buf[0] = addresses >> 8;
        buf[1] = addresses;

        return tda9950_write_range(priv->client, REG_ACKH, buf, 2);
}

/*
 * When operating as part of the TDA998x, we need additional handling
 * to initialise and shut down the TDA9950 part of the device.  These
 * two hooks are provided to allow the TDA998x code to perform those
 * activities.
 */
static int tda9950_glue_open(struct tda9950_priv *priv)
{
        int ret = 0;

        if (priv->glue && priv->glue->open)
                ret = priv->glue->open(priv->glue->data);

        priv->open = true;

        return ret;
}

static void tda9950_glue_release(struct tda9950_priv *priv)
{
        priv->open = false;

        if (priv->glue && priv->glue->release)
                priv->glue->release(priv->glue->data);
}

static int tda9950_open(struct tda9950_priv *priv)
{
        struct i2c_client *client = priv->client;
        int ret;

        ret = tda9950_glue_open(priv);
        if (ret)
                return ret;

        /* Reset the TDA9950, and wait 250ms for it to recover */
        tda9950_write(client, REG_CCR, CCR_RESET);
        msleep(250);

        tda9950_cec_adap_log_addr(priv->adap, CEC_LOG_ADDR_INVALID);

        /* Start the command processor */
        tda9950_write(client, REG_CCR, CCR_ON);

        return 0;
}

static void tda9950_release(struct tda9950_priv *priv)
{
        struct i2c_client *client = priv->client;
        int timeout = 50;
        u8 csr;

        /* Stop the command processor */
        tda9950_write(client, REG_CCR, 0);

        /* Wait up to .5s for it to signal non-busy */
        do {
                csr = tda9950_read(client, REG_CSR);
                if (!(csr & CSR_BUSY) || !--timeout)
                        break;
                msleep(10);
        } while (1);

        /* Warn the user that their IRQ may die if it's shared. */
        if (csr & CSR_BUSY)
                dev_warn(&client->dev, "command processor failed to stop, irq%d may die (csr=0x%02x)\n",
                         client->irq, csr);

        tda9950_glue_release(priv);
}

static int tda9950_cec_adap_enable(struct cec_adapter *adap, bool enable)
{
        struct tda9950_priv *priv = adap->priv;

        if (!enable) {
                tda9950_release(priv);
                return 0;
        } else {
                return tda9950_open(priv);
        }
}

static const struct cec_adap_ops tda9950_cec_ops = {
        .adap_enable = tda9950_cec_adap_enable,
        .adap_log_addr = tda9950_cec_adap_log_addr,
        .adap_transmit = tda9950_cec_transmit,
};

/*
 * When operating as part of the TDA998x, we need to claim additional
 * resources.  These two hooks permit the management of those resources.
 */
static void tda9950_devm_glue_exit(void *data)
{
        struct tda9950_glue *glue = data;

        if (glue && glue->exit)
                glue->exit(glue->data);
}

static int tda9950_devm_glue_init(struct device *dev, struct tda9950_glue *glue)
{
        int ret;

        if (glue && glue->init) {
                ret = glue->init(glue->data);
                if (ret)
                        return ret;
        }

        ret = devm_add_action(dev, tda9950_devm_glue_exit, glue);
        if (ret)
                tda9950_devm_glue_exit(glue);

        return ret;
}

static void tda9950_cec_del(void *data)
{
        struct tda9950_priv *priv = data;

        cec_delete_adapter(priv->adap);
}

static int tda9950_probe(struct i2c_client *client)
{
        struct tda9950_glue *glue = client->dev.platform_data;
        struct device *dev = &client->dev;
        struct tda9950_priv *priv;
        unsigned long irqflags;
        int ret;
        u8 cvr;

        /*
         * We must have I2C functionality: our multi-byte accesses
         * must be performed as a single contiguous transaction.
         */
        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
                dev_err(&client->dev,
                        "adapter does not support I2C functionality\n");
                return -ENXIO;
        }

        /* We must have an interrupt to be functional. */
        if (client->irq <= 0) {
                dev_err(&client->dev, "driver requires an interrupt\n");
                return -ENXIO;
        }

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

        priv->client = client;
        priv->glue = glue;

        i2c_set_clientdata(client, priv);

        /*
         * If we're part of a TDA998x, we want the class devices to be
         * associated with the HDMI Tx so we have a tight relationship
         * between the HDMI interface and the CEC interface.
         */
        priv->hdmi = dev;
        if (glue && glue->parent)
                priv->hdmi = glue->parent;

        priv->adap = cec_allocate_adapter(&tda9950_cec_ops, priv, "tda9950",
                                          CEC_CAP_DEFAULTS |
                                          CEC_CAP_CONNECTOR_INFO,
                                          CEC_MAX_LOG_ADDRS);
        if (IS_ERR(priv->adap))
                return PTR_ERR(priv->adap);

        ret = devm_add_action(dev, tda9950_cec_del, priv);
        if (ret) {
                cec_delete_adapter(priv->adap);
                return ret;
        }

        ret = tda9950_devm_glue_init(dev, glue);
        if (ret)
                return ret;

        ret = tda9950_glue_open(priv);
        if (ret)
                return ret;

        cvr = tda9950_read(client, REG_CVR);

        dev_info(&client->dev,
                 "TDA9950 CEC interface, hardware version %u.%u\n",
                 cvr >> 4, cvr & 15);

        tda9950_glue_release(priv);

        irqflags = IRQF_TRIGGER_FALLING;
        if (glue)
                irqflags = glue->irq_flags;

        ret = devm_request_threaded_irq(dev, client->irq, NULL, tda9950_irq,
                                        irqflags | IRQF_SHARED | IRQF_ONESHOT,
                                        dev_name(&client->dev), priv);
        if (ret < 0)
                return ret;

        priv->notify = cec_notifier_cec_adap_register(priv->hdmi, NULL,
                                                      priv->adap);
        if (!priv->notify)
                return -ENOMEM;

        ret = cec_register_adapter(priv->adap, priv->hdmi);
        if (ret < 0) {
                cec_notifier_cec_adap_unregister(priv->notify, priv->adap);
                return ret;
        }

        /*
         * CEC documentation says we must not call cec_delete_adapter
         * after a successful call to cec_register_adapter().
         */
        devm_remove_action(dev, tda9950_cec_del, priv);

        return 0;
}

static void tda9950_remove(struct i2c_client *client)
{
        struct tda9950_priv *priv = i2c_get_clientdata(client);

        cec_notifier_cec_adap_unregister(priv->notify, priv->adap);
        cec_unregister_adapter(priv->adap);
}

static struct i2c_device_id tda9950_ids[] = {
        { "tda9950" },
        { }
};
MODULE_DEVICE_TABLE(i2c, tda9950_ids);

static struct i2c_driver tda9950_driver = {
        .probe = tda9950_probe,
        .remove = tda9950_remove,
        .driver = {
                .name = "tda9950",
        },
        .id_table = tda9950_ids,
};

module_i2c_driver(tda9950_driver);

MODULE_AUTHOR("Russell King <rmk+kernel@armlinux.org.uk>");
MODULE_DESCRIPTION("TDA9950/TDA998x Consumer Electronics Control Driver");
MODULE_LICENSE("GPL v2");