// SPDX-License-Identifier: GPL-2.0-only
/*
 * Driver for MegaChips STDP4028 with GE B850v3 firmware (LVDS-DP)
 * Driver for MegaChips STDP2690 with GE B850v3 firmware (DP-DP++)

 * Copyright (c) 2017, Collabora Ltd.
 * Copyright (c) 2017, General Electric Company


 * This driver creates a drm_bridge and a drm_connector for the LVDS to DP++
 * display bridge of the GE B850v3. There are two physical bridges on the video
 * signal pipeline: a STDP4028(LVDS to DP) and a STDP2690(DP to DP++). The
 * physical bridges are automatically configured by the input video signal, and
 * the driver has no access to the video processing pipeline. The driver is
 * only needed to read EDID from the STDP2690 and to handle HPD events from the
 * STDP4028. The driver communicates with both bridges over i2c. The video
 * signal pipeline is as follows:
 *
 *   Host -> LVDS|--(STDP4028)--|DP -> DP|--(STDP2690)--|DP++ -> Video output
 */

#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/of.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_bridge.h>
#include <drm/drm_edid.h>
#include <drm/drm_print.h>
#include <drm/drm_probe_helper.h>

#define EDID_EXT_BLOCK_CNT 0x7E

#define STDP4028_IRQ_OUT_CONF_REG 0x02
#define STDP4028_DPTX_IRQ_EN_REG 0x3C
#define STDP4028_DPTX_IRQ_STS_REG 0x3D
#define STDP4028_DPTX_STS_REG 0x3E

#define STDP4028_DPTX_DP_IRQ_EN 0x1000

#define STDP4028_DPTX_HOTPLUG_IRQ_EN 0x0400
#define STDP4028_DPTX_LINK_CH_IRQ_EN 0x2000
#define STDP4028_DPTX_IRQ_CONFIG \
                (STDP4028_DPTX_LINK_CH_IRQ_EN | STDP4028_DPTX_HOTPLUG_IRQ_EN)

#define STDP4028_DPTX_HOTPLUG_STS 0x0200
#define STDP4028_DPTX_LINK_STS 0x1000
#define STDP4028_CON_STATE_CONNECTED \
                (STDP4028_DPTX_HOTPLUG_STS | STDP4028_DPTX_LINK_STS)

#define STDP4028_DPTX_HOTPLUG_CH_STS 0x0400
#define STDP4028_DPTX_LINK_CH_STS 0x2000
#define STDP4028_DPTX_IRQ_CLEAR \
                (STDP4028_DPTX_LINK_CH_STS | STDP4028_DPTX_HOTPLUG_CH_STS)

static DEFINE_MUTEX(ge_b850v3_lvds_dev_mutex);

struct ge_b850v3_lvds {
        struct drm_connector connector;
        struct drm_bridge bridge;
        struct i2c_client *stdp4028_i2c;
        struct i2c_client *stdp2690_i2c;
};

static struct ge_b850v3_lvds *ge_b850v3_lvds_ptr;

static int stdp2690_read_block(void *context, u8 *buf, unsigned int block, size_t len)
{
        struct i2c_client *client = context;
        struct i2c_adapter *adapter = client->adapter;
        unsigned char start = block * EDID_LENGTH;

        struct i2c_msg msgs[] = {
                {
                        .addr   = client->addr,
                        .flags  = 0,
                        .len    = 1,
                        .buf    = &start,
                }, {
                        .addr   = client->addr,
                        .flags  = I2C_M_RD,
                        .len    = len,
                        .buf    = buf,
                }
        };

        if (i2c_transfer(adapter, msgs, 2) != 2)
                return -1;

        return 0;
}

static const struct drm_edid *ge_b850v3_lvds_edid_read(struct drm_bridge *bridge,
                                                       struct drm_connector *connector)
{
        struct i2c_client *client;

        client = ge_b850v3_lvds_ptr->stdp2690_i2c;

        return drm_edid_read_custom(connector, stdp2690_read_block, client);
}

static int ge_b850v3_lvds_get_modes(struct drm_connector *connector)
{
        const struct drm_edid *drm_edid;
        int num_modes;

        drm_edid = ge_b850v3_lvds_edid_read(&ge_b850v3_lvds_ptr->bridge, connector);

        drm_edid_connector_update(connector, drm_edid);
        num_modes = drm_edid_connector_add_modes(connector);
        drm_edid_free(drm_edid);

        return num_modes;
}

static const struct
drm_connector_helper_funcs ge_b850v3_lvds_connector_helper_funcs = {
        .get_modes = ge_b850v3_lvds_get_modes,
};

static enum drm_connector_status
ge_b850v3_lvds_bridge_detect(struct drm_bridge *bridge, struct drm_connector *connector)
{
        struct i2c_client *stdp4028_i2c =
                        ge_b850v3_lvds_ptr->stdp4028_i2c;
        s32 link_state;

        link_state = i2c_smbus_read_word_data(stdp4028_i2c,
                                              STDP4028_DPTX_STS_REG);

        if (link_state == STDP4028_CON_STATE_CONNECTED)
                return connector_status_connected;

        if (link_state == 0)
                return connector_status_disconnected;

        return connector_status_unknown;
}

static enum drm_connector_status ge_b850v3_lvds_detect(struct drm_connector *connector,
                                                       bool force)
{
        return ge_b850v3_lvds_bridge_detect(&ge_b850v3_lvds_ptr->bridge, connector);
}

static const struct drm_connector_funcs ge_b850v3_lvds_connector_funcs = {
        .fill_modes = drm_helper_probe_single_connector_modes,
        .detect = ge_b850v3_lvds_detect,
        .destroy = drm_connector_cleanup,
        .reset = drm_atomic_helper_connector_reset,
        .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
};

static int ge_b850v3_lvds_create_connector(struct drm_bridge *bridge)
{
        struct drm_connector *connector = &ge_b850v3_lvds_ptr->connector;
        int ret;

        connector->polled = DRM_CONNECTOR_POLL_HPD;

        drm_connector_helper_add(connector,
                                 &ge_b850v3_lvds_connector_helper_funcs);

        ret = drm_connector_init(bridge->dev, connector,
                                 &ge_b850v3_lvds_connector_funcs,
                                 DRM_MODE_CONNECTOR_DisplayPort);
        if (ret) {
                DRM_ERROR("Failed to initialize connector with drm\n");
                return ret;
        }

        return drm_connector_attach_encoder(connector, bridge->encoder);
}

static irqreturn_t ge_b850v3_lvds_irq_handler(int irq, void *dev_id)
{
        struct i2c_client *stdp4028_i2c
                        = ge_b850v3_lvds_ptr->stdp4028_i2c;

        i2c_smbus_write_word_data(stdp4028_i2c,
                                  STDP4028_DPTX_IRQ_STS_REG,
                                  STDP4028_DPTX_IRQ_CLEAR);

        if (ge_b850v3_lvds_ptr->bridge.dev)
                drm_kms_helper_hotplug_event(ge_b850v3_lvds_ptr->bridge.dev);

        return IRQ_HANDLED;
}

static int ge_b850v3_lvds_attach(struct drm_bridge *bridge,
                                 struct drm_encoder *encoder,
                                 enum drm_bridge_attach_flags flags)
{
        struct i2c_client *stdp4028_i2c
                        = ge_b850v3_lvds_ptr->stdp4028_i2c;

        /* Configures the bridge to re-enable interrupts after each ack. */
        i2c_smbus_write_word_data(stdp4028_i2c,
                                  STDP4028_IRQ_OUT_CONF_REG,
                                  STDP4028_DPTX_DP_IRQ_EN);

        /* Enable interrupts */
        i2c_smbus_write_word_data(stdp4028_i2c,
                                  STDP4028_DPTX_IRQ_EN_REG,
                                  STDP4028_DPTX_IRQ_CONFIG);

        if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
                return 0;

        return ge_b850v3_lvds_create_connector(bridge);
}

static const struct drm_bridge_funcs ge_b850v3_lvds_funcs = {
        .attach = ge_b850v3_lvds_attach,
        .detect = ge_b850v3_lvds_bridge_detect,
        .edid_read = ge_b850v3_lvds_edid_read,
};

static int ge_b850v3_lvds_init(struct device *dev)
{
        mutex_lock(&ge_b850v3_lvds_dev_mutex);

        if (ge_b850v3_lvds_ptr)
                goto success;

        ge_b850v3_lvds_ptr = devm_drm_bridge_alloc(dev, struct ge_b850v3_lvds, bridge,
                                                   &ge_b850v3_lvds_funcs);
        if (IS_ERR(ge_b850v3_lvds_ptr)) {
                mutex_unlock(&ge_b850v3_lvds_dev_mutex);
                return PTR_ERR(ge_b850v3_lvds_ptr);
        }

success:
        mutex_unlock(&ge_b850v3_lvds_dev_mutex);
        return 0;
}

static void ge_b850v3_lvds_remove(void)
{
        mutex_lock(&ge_b850v3_lvds_dev_mutex);
        /*
         * This check is to avoid both the drivers
         * removing the bridge in their remove() function
         */
        if (!ge_b850v3_lvds_ptr ||
            !ge_b850v3_lvds_ptr->stdp2690_i2c ||
                !ge_b850v3_lvds_ptr->stdp4028_i2c)
                goto out;

        drm_bridge_remove(&ge_b850v3_lvds_ptr->bridge);

        ge_b850v3_lvds_ptr = NULL;
out:
        mutex_unlock(&ge_b850v3_lvds_dev_mutex);
}

static int ge_b850v3_register(void)
{
        struct i2c_client *stdp4028_i2c = ge_b850v3_lvds_ptr->stdp4028_i2c;
        struct device *dev = &stdp4028_i2c->dev;

        /* drm bridge initialization */
        ge_b850v3_lvds_ptr->bridge.ops = DRM_BRIDGE_OP_DETECT |
                                         DRM_BRIDGE_OP_EDID;
        ge_b850v3_lvds_ptr->bridge.type = DRM_MODE_CONNECTOR_DisplayPort;
        ge_b850v3_lvds_ptr->bridge.of_node = dev->of_node;
        drm_bridge_add(&ge_b850v3_lvds_ptr->bridge);

        /* Clear pending interrupts since power up. */
        i2c_smbus_write_word_data(stdp4028_i2c,
                                  STDP4028_DPTX_IRQ_STS_REG,
                                  STDP4028_DPTX_IRQ_CLEAR);

        if (!stdp4028_i2c->irq)
                return 0;

        return devm_request_threaded_irq(&stdp4028_i2c->dev,
                        stdp4028_i2c->irq, NULL,
                        ge_b850v3_lvds_irq_handler,
                        IRQF_TRIGGER_HIGH | IRQF_ONESHOT,
                        "ge-b850v3-lvds-dp", ge_b850v3_lvds_ptr);
}

static int stdp4028_ge_b850v3_fw_probe(struct i2c_client *stdp4028_i2c)
{
        struct device *dev = &stdp4028_i2c->dev;
        int ret;

        ret = ge_b850v3_lvds_init(dev);

        if (ret)
                return ret;

        ge_b850v3_lvds_ptr->stdp4028_i2c = stdp4028_i2c;
        i2c_set_clientdata(stdp4028_i2c, ge_b850v3_lvds_ptr);

        /* Only register after both bridges are probed */
        if (!ge_b850v3_lvds_ptr->stdp2690_i2c)
                return 0;

        return ge_b850v3_register();
}

static void stdp4028_ge_b850v3_fw_remove(struct i2c_client *stdp4028_i2c)
{
        ge_b850v3_lvds_remove();
}

static const struct i2c_device_id stdp4028_ge_b850v3_fw_i2c_table[] = {
        { "stdp4028_ge_fw" },
        {}
};
MODULE_DEVICE_TABLE(i2c, stdp4028_ge_b850v3_fw_i2c_table);

static const struct of_device_id stdp4028_ge_b850v3_fw_match[] = {
        { .compatible = "megachips,stdp4028-ge-b850v3-fw" },
        {},
};
MODULE_DEVICE_TABLE(of, stdp4028_ge_b850v3_fw_match);

static struct i2c_driver stdp4028_ge_b850v3_fw_driver = {
        .id_table       = stdp4028_ge_b850v3_fw_i2c_table,
        .probe          = stdp4028_ge_b850v3_fw_probe,
        .remove         = stdp4028_ge_b850v3_fw_remove,
        .driver         = {
                .name           = "stdp4028-ge-b850v3-fw",
                .of_match_table = stdp4028_ge_b850v3_fw_match,
        },
};

static int stdp2690_ge_b850v3_fw_probe(struct i2c_client *stdp2690_i2c)
{
        struct device *dev = &stdp2690_i2c->dev;
        int ret;

        ret = ge_b850v3_lvds_init(dev);

        if (ret)
                return ret;

        ge_b850v3_lvds_ptr->stdp2690_i2c = stdp2690_i2c;
        i2c_set_clientdata(stdp2690_i2c, ge_b850v3_lvds_ptr);

        /* Only register after both bridges are probed */
        if (!ge_b850v3_lvds_ptr->stdp4028_i2c)
                return 0;

        return ge_b850v3_register();
}

static void stdp2690_ge_b850v3_fw_remove(struct i2c_client *stdp2690_i2c)
{
        ge_b850v3_lvds_remove();
}

static const struct i2c_device_id stdp2690_ge_b850v3_fw_i2c_table[] = {
        { "stdp2690_ge_fw" },
        {}
};
MODULE_DEVICE_TABLE(i2c, stdp2690_ge_b850v3_fw_i2c_table);

static const struct of_device_id stdp2690_ge_b850v3_fw_match[] = {
        { .compatible = "megachips,stdp2690-ge-b850v3-fw" },
        {},
};
MODULE_DEVICE_TABLE(of, stdp2690_ge_b850v3_fw_match);

static struct i2c_driver stdp2690_ge_b850v3_fw_driver = {
        .id_table       = stdp2690_ge_b850v3_fw_i2c_table,
        .probe          = stdp2690_ge_b850v3_fw_probe,
        .remove         = stdp2690_ge_b850v3_fw_remove,
        .driver         = {
                .name           = "stdp2690-ge-b850v3-fw",
                .of_match_table = stdp2690_ge_b850v3_fw_match,
        },
};

static int __init stdpxxxx_ge_b850v3_init(void)
{
        int ret;

        ret = i2c_add_driver(&stdp4028_ge_b850v3_fw_driver);
        if (ret)
                return ret;

        ret = i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
        if (ret)
                i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);

        return ret;
}
module_init(stdpxxxx_ge_b850v3_init);

static void __exit stdpxxxx_ge_b850v3_exit(void)
{
        i2c_del_driver(&stdp2690_ge_b850v3_fw_driver);
        i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
}
module_exit(stdpxxxx_ge_b850v3_exit);

MODULE_AUTHOR("Peter Senna Tschudin <peter.senna@collabora.com>");
MODULE_AUTHOR("Martyn Welch <martyn.welch@collabora.co.uk>");
MODULE_DESCRIPTION("GE LVDS to DP++ display bridge)");
MODULE_LICENSE("GPL v2");