// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2015-2016 Free Electrons
 * Copyright (C) 2015-2016 NextThing Co
 *
 * Maxime Ripard <maxime.ripard@free-electrons.com>
 */

#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/of_graph.h>
#include <linux/regulator/consumer.h>

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

struct simple_bridge_info {
        const struct drm_bridge_timings *timings;
        unsigned int connector_type;
};

struct simple_bridge {
        struct drm_bridge       bridge;
        struct drm_connector    connector;

        const struct simple_bridge_info *info;

        struct drm_bridge       *next_bridge;
        struct regulator        *vdd;
        struct gpio_desc        *enable;
};

static inline struct simple_bridge *
drm_bridge_to_simple_bridge(struct drm_bridge *bridge)
{
        return container_of(bridge, struct simple_bridge, bridge);
}

static inline struct simple_bridge *
drm_connector_to_simple_bridge(struct drm_connector *connector)
{
        return container_of(connector, struct simple_bridge, connector);
}

static int simple_bridge_get_modes(struct drm_connector *connector)
{
        struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);
        struct edid *edid;
        int ret;

        if (sbridge->next_bridge->ops & DRM_BRIDGE_OP_EDID) {
                edid = drm_bridge_get_edid(sbridge->next_bridge, connector);
                if (!edid)
                        DRM_INFO("EDID read failed. Fallback to standard modes\n");
        } else {
                edid = NULL;
        }

        if (!edid) {
                /*
                 * In case we cannot retrieve the EDIDs (missing or broken DDC
                 * bus from the next bridge), fallback on the XGA standards and
                 * prefer a mode pretty much anyone can handle.
                 */
                ret = drm_add_modes_noedid(connector, 1920, 1200);
                drm_set_preferred_mode(connector, 1024, 768);
                return ret;
        }

        drm_connector_update_edid_property(connector, edid);
        ret = drm_add_edid_modes(connector, edid);
        kfree(edid);

        return ret;
}

static const struct drm_connector_helper_funcs simple_bridge_con_helper_funcs = {
        .get_modes      = simple_bridge_get_modes,
};

static enum drm_connector_status
simple_bridge_connector_detect(struct drm_connector *connector, bool force)
{
        struct simple_bridge *sbridge = drm_connector_to_simple_bridge(connector);

        return drm_bridge_detect(sbridge->next_bridge);
}

static const struct drm_connector_funcs simple_bridge_con_funcs = {
        .detect                 = simple_bridge_connector_detect,
        .fill_modes             = drm_helper_probe_single_connector_modes,
        .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 simple_bridge_attach(struct drm_bridge *bridge,
                                enum drm_bridge_attach_flags flags)
{
        struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
        int ret;

        ret = drm_bridge_attach(bridge->encoder, sbridge->next_bridge, bridge,
                                DRM_BRIDGE_ATTACH_NO_CONNECTOR);
        if (ret < 0)
                return ret;

        if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
                return 0;

        if (!bridge->encoder) {
                DRM_ERROR("Missing encoder\n");
                return -ENODEV;
        }

        drm_connector_helper_add(&sbridge->connector,
                                 &simple_bridge_con_helper_funcs);
        ret = drm_connector_init_with_ddc(bridge->dev, &sbridge->connector,
                                          &simple_bridge_con_funcs,
                                          sbridge->info->connector_type,
                                          sbridge->next_bridge->ddc);
        if (ret) {
                DRM_ERROR("Failed to initialize connector\n");
                return ret;
        }

        drm_connector_attach_encoder(&sbridge->connector, bridge->encoder);

        return 0;
}

static void simple_bridge_enable(struct drm_bridge *bridge)
{
        struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);
        int ret;

        if (sbridge->vdd) {
                ret = regulator_enable(sbridge->vdd);
                if (ret)
                        DRM_ERROR("Failed to enable vdd regulator: %d\n", ret);
        }

        gpiod_set_value_cansleep(sbridge->enable, 1);
}

static void simple_bridge_disable(struct drm_bridge *bridge)
{
        struct simple_bridge *sbridge = drm_bridge_to_simple_bridge(bridge);

        gpiod_set_value_cansleep(sbridge->enable, 0);

        if (sbridge->vdd)
                regulator_disable(sbridge->vdd);
}

static const struct drm_bridge_funcs simple_bridge_bridge_funcs = {
        .attach         = simple_bridge_attach,
        .enable         = simple_bridge_enable,
        .disable        = simple_bridge_disable,
};

static int simple_bridge_probe(struct platform_device *pdev)
{
        struct simple_bridge *sbridge;
        struct device_node *remote;

        sbridge = devm_kzalloc(&pdev->dev, sizeof(*sbridge), GFP_KERNEL);
        if (!sbridge)
                return -ENOMEM;
        platform_set_drvdata(pdev, sbridge);

        sbridge->info = of_device_get_match_data(&pdev->dev);

        /* Get the next bridge in the pipeline. */
        remote = of_graph_get_remote_node(pdev->dev.of_node, 1, -1);
        if (!remote)
                return -EINVAL;

        sbridge->next_bridge = of_drm_find_bridge(remote);
        of_node_put(remote);

        if (!sbridge->next_bridge) {
                dev_dbg(&pdev->dev, "Next bridge not found, deferring probe\n");
                return -EPROBE_DEFER;
        }

        /* Get the regulator and GPIO resources. */
        sbridge->vdd = devm_regulator_get_optional(&pdev->dev, "vdd");
        if (IS_ERR(sbridge->vdd)) {
                int ret = PTR_ERR(sbridge->vdd);
                if (ret == -EPROBE_DEFER)
                        return -EPROBE_DEFER;
                sbridge->vdd = NULL;
                dev_dbg(&pdev->dev, "No vdd regulator found: %d\n", ret);
        }

        sbridge->enable = devm_gpiod_get_optional(&pdev->dev, "enable",
                                                  GPIOD_OUT_LOW);
        if (IS_ERR(sbridge->enable)) {
                if (PTR_ERR(sbridge->enable) != -EPROBE_DEFER)
                        dev_err(&pdev->dev, "Unable to retrieve enable GPIO\n");
                return PTR_ERR(sbridge->enable);
        }

        /* Register the bridge. */
        sbridge->bridge.funcs = &simple_bridge_bridge_funcs;
        sbridge->bridge.of_node = pdev->dev.of_node;
        sbridge->bridge.timings = sbridge->info->timings;

        drm_bridge_add(&sbridge->bridge);

        return 0;
}

static int simple_bridge_remove(struct platform_device *pdev)
{
        struct simple_bridge *sbridge = platform_get_drvdata(pdev);

        drm_bridge_remove(&sbridge->bridge);

        return 0;
}

/*
 * We assume the ADV7123 DAC is the "default" for historical reasons
 * Information taken from the ADV7123 datasheet, revision D.
 * NOTE: the ADV7123EP seems to have other timings and need a new timings
 * set if used.
 */
static const struct drm_bridge_timings default_bridge_timings = {
        /* Timing specifications, datasheet page 7 */
        .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
        .setup_time_ps = 500,
        .hold_time_ps = 1500,
};

/*
 * Information taken from the THS8134, THS8134A, THS8134B datasheet named
 * "SLVS205D", dated May 1990, revised March 2000.
 */
static const struct drm_bridge_timings ti_ths8134_bridge_timings = {
        /* From timing diagram, datasheet page 9 */
        .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
        /* From datasheet, page 12 */
        .setup_time_ps = 3000,
        /* I guess this means latched input */
        .hold_time_ps = 0,
};

/*
 * Information taken from the THS8135 datasheet named "SLAS343B", dated
 * May 2001, revised April 2013.
 */
static const struct drm_bridge_timings ti_ths8135_bridge_timings = {
        /* From timing diagram, datasheet page 14 */
        .input_bus_flags = DRM_BUS_FLAG_PIXDATA_SAMPLE_POSEDGE,
        /* From datasheet, page 16 */
        .setup_time_ps = 2000,
        .hold_time_ps = 500,
};

static const struct of_device_id simple_bridge_match[] = {
        {
                .compatible = "dumb-vga-dac",
                .data = &(const struct simple_bridge_info) {
                        .connector_type = DRM_MODE_CONNECTOR_VGA,
                },
        }, {
                .compatible = "adi,adv7123",
                .data = &(const struct simple_bridge_info) {
                        .timings = &default_bridge_timings,
                        .connector_type = DRM_MODE_CONNECTOR_VGA,
                },
        }, {
                .compatible = "ti,opa362",
                .data = &(const struct simple_bridge_info) {
                        .connector_type = DRM_MODE_CONNECTOR_Composite,
                },
        }, {
                .compatible = "ti,ths8135",
                .data = &(const struct simple_bridge_info) {
                        .timings = &ti_ths8135_bridge_timings,
                        .connector_type = DRM_MODE_CONNECTOR_VGA,
                },
        }, {
                .compatible = "ti,ths8134",
                .data = &(const struct simple_bridge_info) {
                        .timings = &ti_ths8134_bridge_timings,
                        .connector_type = DRM_MODE_CONNECTOR_VGA,
                },
        },
        {},
};
MODULE_DEVICE_TABLE(of, simple_bridge_match);

static struct platform_driver simple_bridge_driver = {
        .probe  = simple_bridge_probe,
        .remove = simple_bridge_remove,
        .driver         = {
                .name           = "simple-bridge",
                .of_match_table = simple_bridge_match,
        },
};
module_platform_driver(simple_bridge_driver);

MODULE_AUTHOR("Maxime Ripard <maxime.ripard@free-electrons.com>");
MODULE_DESCRIPTION("Simple DRM bridge driver");
MODULE_LICENSE("GPL");