// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2018, The Linux Foundation. All rights reserved.
 */

#include <linux/clk.h>
#include <linux/gpio/consumer.h>
#include <linux/i2c.h>
#include <linux/iopoll.h>
#include <linux/module.h>
#include <linux/of_graph.h>
#include <linux/pm_runtime.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_dp_helper.h>
#include <drm/drm_mipi_dsi.h>
#include <drm/drm_of.h>
#include <drm/drm_panel.h>
#include <drm/drm_print.h>
#include <drm/drm_probe_helper.h>

#define SN_DEVICE_REV_REG                       0x08
#define SN_DPPLL_SRC_REG                        0x0A
#define  DPPLL_CLK_SRC_DSICLK                   BIT(0)
#define  REFCLK_FREQ_MASK                       GENMASK(3, 1)
#define  REFCLK_FREQ(x)                         ((x) << 1)
#define  DPPLL_SRC_DP_PLL_LOCK                  BIT(7)
#define SN_PLL_ENABLE_REG                       0x0D
#define SN_DSI_LANES_REG                        0x10
#define  CHA_DSI_LANES_MASK                     GENMASK(4, 3)
#define  CHA_DSI_LANES(x)                       ((x) << 3)
#define SN_DSIA_CLK_FREQ_REG                    0x12
#define SN_CHA_ACTIVE_LINE_LENGTH_LOW_REG       0x20
#define SN_CHA_VERTICAL_DISPLAY_SIZE_LOW_REG    0x24
#define SN_CHA_HSYNC_PULSE_WIDTH_LOW_REG        0x2C
#define SN_CHA_HSYNC_PULSE_WIDTH_HIGH_REG       0x2D
#define  CHA_HSYNC_POLARITY                     BIT(7)
#define SN_CHA_VSYNC_PULSE_WIDTH_LOW_REG        0x30
#define SN_CHA_VSYNC_PULSE_WIDTH_HIGH_REG       0x31
#define  CHA_VSYNC_POLARITY                     BIT(7)
#define SN_CHA_HORIZONTAL_BACK_PORCH_REG        0x34
#define SN_CHA_VERTICAL_BACK_PORCH_REG          0x36
#define SN_CHA_HORIZONTAL_FRONT_PORCH_REG       0x38
#define SN_CHA_VERTICAL_FRONT_PORCH_REG         0x3A
#define SN_ENH_FRAME_REG                        0x5A
#define  VSTREAM_ENABLE                         BIT(3)
#define SN_DATA_FORMAT_REG                      0x5B
#define SN_HPD_DISABLE_REG                      0x5C
#define  HPD_DISABLE                            BIT(0)
#define SN_AUX_WDATA_REG(x)                     (0x64 + (x))
#define SN_AUX_ADDR_19_16_REG                   0x74
#define SN_AUX_ADDR_15_8_REG                    0x75
#define SN_AUX_ADDR_7_0_REG                     0x76
#define SN_AUX_LENGTH_REG                       0x77
#define SN_AUX_CMD_REG                          0x78
#define  AUX_CMD_SEND                           BIT(0)
#define  AUX_CMD_REQ(x)                         ((x) << 4)
#define SN_AUX_RDATA_REG(x)                     (0x79 + (x))
#define SN_SSC_CONFIG_REG                       0x93
#define  DP_NUM_LANES_MASK                      GENMASK(5, 4)
#define  DP_NUM_LANES(x)                        ((x) << 4)
#define SN_DATARATE_CONFIG_REG                  0x94
#define  DP_DATARATE_MASK                       GENMASK(7, 5)
#define  DP_DATARATE(x)                         ((x) << 5)
#define SN_ML_TX_MODE_REG                       0x96
#define  ML_TX_MAIN_LINK_OFF                    0
#define  ML_TX_NORMAL_MODE                      BIT(0)
#define SN_AUX_CMD_STATUS_REG                   0xF4
#define  AUX_IRQ_STATUS_AUX_RPLY_TOUT           BIT(3)
#define  AUX_IRQ_STATUS_AUX_SHORT               BIT(5)
#define  AUX_IRQ_STATUS_NAT_I2C_FAIL            BIT(6)

#define MIN_DSI_CLK_FREQ_MHZ    40

/* fudge factor required to account for 8b/10b encoding */
#define DP_CLK_FUDGE_NUM        10
#define DP_CLK_FUDGE_DEN        8

/* Matches DP_AUX_MAX_PAYLOAD_BYTES (for now) */
#define SN_AUX_MAX_PAYLOAD_BYTES        16

#define SN_REGULATOR_SUPPLY_NUM         4

struct ti_sn_bridge {
        struct device                   *dev;
        struct regmap                   *regmap;
        struct drm_dp_aux               aux;
        struct drm_bridge               bridge;
        struct drm_connector            connector;
        struct device_node              *host_node;
        struct mipi_dsi_device          *dsi;
        struct clk                      *refclk;
        struct drm_panel                *panel;
        struct gpio_desc                *enable_gpio;
        struct regulator_bulk_data      supplies[SN_REGULATOR_SUPPLY_NUM];
};

static const struct regmap_range ti_sn_bridge_volatile_ranges[] = {
        { .range_min = 0, .range_max = 0xFF },
};

static const struct regmap_access_table ti_sn_bridge_volatile_table = {
        .yes_ranges = ti_sn_bridge_volatile_ranges,
        .n_yes_ranges = ARRAY_SIZE(ti_sn_bridge_volatile_ranges),
};

static const struct regmap_config ti_sn_bridge_regmap_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .volatile_table = &ti_sn_bridge_volatile_table,
        .cache_type = REGCACHE_NONE,
};

static void ti_sn_bridge_write_u16(struct ti_sn_bridge *pdata,
                                   unsigned int reg, u16 val)
{
        regmap_write(pdata->regmap, reg, val & 0xFF);
        regmap_write(pdata->regmap, reg + 1, val >> 8);
}

static int __maybe_unused ti_sn_bridge_resume(struct device *dev)
{
        struct ti_sn_bridge *pdata = dev_get_drvdata(dev);
        int ret;

        ret = regulator_bulk_enable(SN_REGULATOR_SUPPLY_NUM, pdata->supplies);
        if (ret) {
                DRM_ERROR("failed to enable supplies %d\n", ret);
                return ret;
        }

        gpiod_set_value(pdata->enable_gpio, 1);

        return ret;
}

static int __maybe_unused ti_sn_bridge_suspend(struct device *dev)
{
        struct ti_sn_bridge *pdata = dev_get_drvdata(dev);
        int ret;

        gpiod_set_value(pdata->enable_gpio, 0);

        ret = regulator_bulk_disable(SN_REGULATOR_SUPPLY_NUM, pdata->supplies);
        if (ret)
                DRM_ERROR("failed to disable supplies %d\n", ret);

        return ret;
}

static const struct dev_pm_ops ti_sn_bridge_pm_ops = {
        SET_RUNTIME_PM_OPS(ti_sn_bridge_suspend, ti_sn_bridge_resume, NULL)
};

/* Connector funcs */
static struct ti_sn_bridge *
connector_to_ti_sn_bridge(struct drm_connector *connector)
{
        return container_of(connector, struct ti_sn_bridge, connector);
}

static int ti_sn_bridge_connector_get_modes(struct drm_connector *connector)
{
        struct ti_sn_bridge *pdata = connector_to_ti_sn_bridge(connector);

        return drm_panel_get_modes(pdata->panel);
}

static enum drm_mode_status
ti_sn_bridge_connector_mode_valid(struct drm_connector *connector,
                                  struct drm_display_mode *mode)
{
        /* maximum supported resolution is 4K at 60 fps */
        if (mode->clock > 594000)
                return MODE_CLOCK_HIGH;

        return MODE_OK;
}

static struct drm_connector_helper_funcs ti_sn_bridge_connector_helper_funcs = {
        .get_modes = ti_sn_bridge_connector_get_modes,
        .mode_valid = ti_sn_bridge_connector_mode_valid,
};

static enum drm_connector_status
ti_sn_bridge_connector_detect(struct drm_connector *connector, bool force)
{
        /**
         * TODO: Currently if drm_panel is present, then always
         * return the status as connected. Need to add support to detect
         * device state for hot pluggable scenarios.
         */
        return connector_status_connected;
}

static const struct drm_connector_funcs ti_sn_bridge_connector_funcs = {
        .fill_modes = drm_helper_probe_single_connector_modes,
        .detect = ti_sn_bridge_connector_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 struct ti_sn_bridge *bridge_to_ti_sn_bridge(struct drm_bridge *bridge)
{
        return container_of(bridge, struct ti_sn_bridge, bridge);
}

static int ti_sn_bridge_parse_regulators(struct ti_sn_bridge *pdata)
{
        unsigned int i;
        const char * const ti_sn_bridge_supply_names[] = {
                "vcca", "vcc", "vccio", "vpll",
        };

        for (i = 0; i < SN_REGULATOR_SUPPLY_NUM; i++)
                pdata->supplies[i].supply = ti_sn_bridge_supply_names[i];

        return devm_regulator_bulk_get(pdata->dev, SN_REGULATOR_SUPPLY_NUM,
                                       pdata->supplies);
}

static int ti_sn_bridge_attach(struct drm_bridge *bridge)
{
        int ret, val;
        struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
        struct mipi_dsi_host *host;
        struct mipi_dsi_device *dsi;
        const struct mipi_dsi_device_info info = { .type = "ti_sn_bridge",
                                                   .channel = 0,
                                                   .node = NULL,
                                                 };

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

        drm_connector_helper_add(&pdata->connector,
                                 &ti_sn_bridge_connector_helper_funcs);
        drm_connector_attach_encoder(&pdata->connector, bridge->encoder);

        /*
         * TODO: ideally finding host resource and dsi dev registration needs
         * to be done in bridge probe. But some existing DSI host drivers will
         * wait for any of the drm_bridge/drm_panel to get added to the global
         * bridge/panel list, before completing their probe. So if we do the
         * dsi dev registration part in bridge probe, before populating in
         * the global bridge list, then it will cause deadlock as dsi host probe
         * will never complete, neither our bridge probe. So keeping it here
         * will satisfy most of the existing host drivers. Once the host driver
         * is fixed we can move the below code to bridge probe safely.
         */
        host = of_find_mipi_dsi_host_by_node(pdata->host_node);
        if (!host) {
                DRM_ERROR("failed to find dsi host\n");
                ret = -ENODEV;
                goto err_dsi_host;
        }

        dsi = mipi_dsi_device_register_full(host, &info);
        if (IS_ERR(dsi)) {
                DRM_ERROR("failed to create dsi device\n");
                ret = PTR_ERR(dsi);
                goto err_dsi_host;
        }

        /* TODO: setting to 4 lanes always for now */
        dsi->lanes = 4;
        dsi->format = MIPI_DSI_FMT_RGB888;
        dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_SYNC_PULSE |
                          MIPI_DSI_MODE_EOT_PACKET | MIPI_DSI_MODE_VIDEO_HSE;

        /* check if continuous dsi clock is required or not */
        pm_runtime_get_sync(pdata->dev);
        regmap_read(pdata->regmap, SN_DPPLL_SRC_REG, &val);
        pm_runtime_put(pdata->dev);
        if (!(val & DPPLL_CLK_SRC_DSICLK))
                dsi->mode_flags |= MIPI_DSI_CLOCK_NON_CONTINUOUS;

        ret = mipi_dsi_attach(dsi);
        if (ret < 0) {
                DRM_ERROR("failed to attach dsi to host\n");
                goto err_dsi_attach;
        }
        pdata->dsi = dsi;

        /* attach panel to bridge */
        drm_panel_attach(pdata->panel, &pdata->connector);

        return 0;

err_dsi_attach:
        mipi_dsi_device_unregister(dsi);
err_dsi_host:
        drm_connector_cleanup(&pdata->connector);
        return ret;
}

static void ti_sn_bridge_disable(struct drm_bridge *bridge)
{
        struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);

        drm_panel_disable(pdata->panel);

        /* disable video stream */
        regmap_update_bits(pdata->regmap, SN_ENH_FRAME_REG, VSTREAM_ENABLE, 0);
        /* semi auto link training mode OFF */
        regmap_write(pdata->regmap, SN_ML_TX_MODE_REG, 0);
        /* disable DP PLL */
        regmap_write(pdata->regmap, SN_PLL_ENABLE_REG, 0);

        drm_panel_unprepare(pdata->panel);
}

static u32 ti_sn_bridge_get_dsi_freq(struct ti_sn_bridge *pdata)
{
        u32 bit_rate_khz, clk_freq_khz;
        struct drm_display_mode *mode =
                &pdata->bridge.encoder->crtc->state->adjusted_mode;

        bit_rate_khz = mode->clock *
                        mipi_dsi_pixel_format_to_bpp(pdata->dsi->format);
        clk_freq_khz = bit_rate_khz / (pdata->dsi->lanes * 2);

        return clk_freq_khz;
}

/* clk frequencies supported by bridge in Hz in case derived from REFCLK pin */
static const u32 ti_sn_bridge_refclk_lut[] = {
        12000000,
        19200000,
        26000000,
        27000000,
        38400000,
};

/* clk frequencies supported by bridge in Hz in case derived from DACP/N pin */
static const u32 ti_sn_bridge_dsiclk_lut[] = {
        468000000,
        384000000,
        416000000,
        486000000,
        460800000,
};

static void ti_sn_bridge_set_refclk_freq(struct ti_sn_bridge *pdata)
{
        int i;
        u32 refclk_rate;
        const u32 *refclk_lut;
        size_t refclk_lut_size;

        if (pdata->refclk) {
                refclk_rate = clk_get_rate(pdata->refclk);
                refclk_lut = ti_sn_bridge_refclk_lut;
                refclk_lut_size = ARRAY_SIZE(ti_sn_bridge_refclk_lut);
                clk_prepare_enable(pdata->refclk);
        } else {
                refclk_rate = ti_sn_bridge_get_dsi_freq(pdata) * 1000;
                refclk_lut = ti_sn_bridge_dsiclk_lut;
                refclk_lut_size = ARRAY_SIZE(ti_sn_bridge_dsiclk_lut);
        }

        /* for i equals to refclk_lut_size means default frequency */
        for (i = 0; i < refclk_lut_size; i++)
                if (refclk_lut[i] == refclk_rate)
                        break;

        regmap_update_bits(pdata->regmap, SN_DPPLL_SRC_REG, REFCLK_FREQ_MASK,
                           REFCLK_FREQ(i));
}

/**
 * LUT index corresponds to register value and
 * LUT values corresponds to dp data rate supported
 * by the bridge in Mbps unit.
 */
static const unsigned int ti_sn_bridge_dp_rate_lut[] = {
        0, 1620, 2160, 2430, 2700, 3240, 4320, 5400
};

static void ti_sn_bridge_set_dsi_dp_rate(struct ti_sn_bridge *pdata)
{
        unsigned int bit_rate_mhz, clk_freq_mhz, dp_rate_mhz;
        unsigned int val, i;
        struct drm_display_mode *mode =
                &pdata->bridge.encoder->crtc->state->adjusted_mode;

        /* set DSIA clk frequency */
        bit_rate_mhz = (mode->clock / 1000) *
                        mipi_dsi_pixel_format_to_bpp(pdata->dsi->format);
        clk_freq_mhz = bit_rate_mhz / (pdata->dsi->lanes * 2);

        /* for each increment in val, frequency increases by 5MHz */
        val = (MIN_DSI_CLK_FREQ_MHZ / 5) +
                (((clk_freq_mhz - MIN_DSI_CLK_FREQ_MHZ) / 5) & 0xFF);
        regmap_write(pdata->regmap, SN_DSIA_CLK_FREQ_REG, val);

        /* set DP data rate */
        dp_rate_mhz = ((bit_rate_mhz / pdata->dsi->lanes) * DP_CLK_FUDGE_NUM) /
                                                        DP_CLK_FUDGE_DEN;
        for (i = 0; i < ARRAY_SIZE(ti_sn_bridge_dp_rate_lut) - 1; i++)
                if (ti_sn_bridge_dp_rate_lut[i] > dp_rate_mhz)
                        break;

        regmap_update_bits(pdata->regmap, SN_DATARATE_CONFIG_REG,
                           DP_DATARATE_MASK, DP_DATARATE(i));
}

static void ti_sn_bridge_set_video_timings(struct ti_sn_bridge *pdata)
{
        struct drm_display_mode *mode =
                &pdata->bridge.encoder->crtc->state->adjusted_mode;
        u8 hsync_polarity = 0, vsync_polarity = 0;

        if (mode->flags & DRM_MODE_FLAG_PHSYNC)
                hsync_polarity = CHA_HSYNC_POLARITY;
        if (mode->flags & DRM_MODE_FLAG_PVSYNC)
                vsync_polarity = CHA_VSYNC_POLARITY;

        ti_sn_bridge_write_u16(pdata, SN_CHA_ACTIVE_LINE_LENGTH_LOW_REG,
                               mode->hdisplay);
        ti_sn_bridge_write_u16(pdata, SN_CHA_VERTICAL_DISPLAY_SIZE_LOW_REG,
                               mode->vdisplay);
        regmap_write(pdata->regmap, SN_CHA_HSYNC_PULSE_WIDTH_LOW_REG,
                     (mode->hsync_end - mode->hsync_start) & 0xFF);
        regmap_write(pdata->regmap, SN_CHA_HSYNC_PULSE_WIDTH_HIGH_REG,
                     (((mode->hsync_end - mode->hsync_start) >> 8) & 0x7F) |
                     hsync_polarity);
        regmap_write(pdata->regmap, SN_CHA_VSYNC_PULSE_WIDTH_LOW_REG,
                     (mode->vsync_end - mode->vsync_start) & 0xFF);
        regmap_write(pdata->regmap, SN_CHA_VSYNC_PULSE_WIDTH_HIGH_REG,
                     (((mode->vsync_end - mode->vsync_start) >> 8) & 0x7F) |
                     vsync_polarity);

        regmap_write(pdata->regmap, SN_CHA_HORIZONTAL_BACK_PORCH_REG,
                     (mode->htotal - mode->hsync_end) & 0xFF);
        regmap_write(pdata->regmap, SN_CHA_VERTICAL_BACK_PORCH_REG,
                     (mode->vtotal - mode->vsync_end) & 0xFF);

        regmap_write(pdata->regmap, SN_CHA_HORIZONTAL_FRONT_PORCH_REG,
                     (mode->hsync_start - mode->hdisplay) & 0xFF);
        regmap_write(pdata->regmap, SN_CHA_VERTICAL_FRONT_PORCH_REG,
                     (mode->vsync_start - mode->vdisplay) & 0xFF);

        usleep_range(10000, 10500); /* 10ms delay recommended by spec */
}

static void ti_sn_bridge_enable(struct drm_bridge *bridge)
{
        struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);
        unsigned int val;
        int ret;

        /* DSI_A lane config */
        val = CHA_DSI_LANES(4 - pdata->dsi->lanes);
        regmap_update_bits(pdata->regmap, SN_DSI_LANES_REG,
                           CHA_DSI_LANES_MASK, val);

        /* DP lane config */
        val = DP_NUM_LANES(pdata->dsi->lanes - 1);
        regmap_update_bits(pdata->regmap, SN_SSC_CONFIG_REG, DP_NUM_LANES_MASK,
                           val);

        /* set dsi/dp clk frequency value */
        ti_sn_bridge_set_dsi_dp_rate(pdata);

        /* enable DP PLL */
        regmap_write(pdata->regmap, SN_PLL_ENABLE_REG, 1);

        ret = regmap_read_poll_timeout(pdata->regmap, SN_DPPLL_SRC_REG, val,
                                       val & DPPLL_SRC_DP_PLL_LOCK, 1000,
                                       50 * 1000);
        if (ret) {
                DRM_ERROR("DP_PLL_LOCK polling failed (%d)\n", ret);
                return;
        }

        /**
         * The SN65DSI86 only supports ASSR Display Authentication method and
         * this method is enabled by default. An eDP panel must support this
         * authentication method. We need to enable this method in the eDP panel
         * at DisplayPort address 0x0010A prior to link training.
         */
        drm_dp_dpcd_writeb(&pdata->aux, DP_EDP_CONFIGURATION_SET,
                           DP_ALTERNATE_SCRAMBLER_RESET_ENABLE);

        /* Semi auto link training mode */
        regmap_write(pdata->regmap, SN_ML_TX_MODE_REG, 0x0A);
        ret = regmap_read_poll_timeout(pdata->regmap, SN_ML_TX_MODE_REG, val,
                                       val == ML_TX_MAIN_LINK_OFF ||
                                       val == ML_TX_NORMAL_MODE, 1000,
                                       500 * 1000);
        if (ret) {
                DRM_ERROR("Training complete polling failed (%d)\n", ret);
                return;
        } else if (val == ML_TX_MAIN_LINK_OFF) {
                DRM_ERROR("Link training failed, link is off\n");
                return;
        }

        /* config video parameters */
        ti_sn_bridge_set_video_timings(pdata);

        /* enable video stream */
        regmap_update_bits(pdata->regmap, SN_ENH_FRAME_REG, VSTREAM_ENABLE,
                           VSTREAM_ENABLE);

        drm_panel_enable(pdata->panel);
}

static void ti_sn_bridge_pre_enable(struct drm_bridge *bridge)
{
        struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);

        pm_runtime_get_sync(pdata->dev);

        /* configure bridge ref_clk */
        ti_sn_bridge_set_refclk_freq(pdata);

        /*
         * HPD on this bridge chip is a bit useless.  This is an eDP bridge
         * so the HPD is an internal signal that's only there to signal that
         * the panel is done powering up.  ...but the bridge chip debounces
         * this signal by between 100 ms and 400 ms (depending on process,
         * voltage, and temperate--I measured it at about 200 ms).  One
         * particular panel asserted HPD 84 ms after it was powered on meaning
         * that we saw HPD 284 ms after power on.  ...but the same panel said
         * that instead of looking at HPD you could just hardcode a delay of
         * 200 ms.  We'll assume that the panel driver will have the hardcoded
         * delay in its prepare and always disable HPD.
         *
         * If HPD somehow makes sense on some future panel we'll have to
         * change this to be conditional on someone specifying that HPD should
         * be used.
         */
        regmap_update_bits(pdata->regmap, SN_HPD_DISABLE_REG, HPD_DISABLE,
                           HPD_DISABLE);

        drm_panel_prepare(pdata->panel);
}

static void ti_sn_bridge_post_disable(struct drm_bridge *bridge)
{
        struct ti_sn_bridge *pdata = bridge_to_ti_sn_bridge(bridge);

        if (pdata->refclk)
                clk_disable_unprepare(pdata->refclk);

        pm_runtime_put_sync(pdata->dev);
}

static const struct drm_bridge_funcs ti_sn_bridge_funcs = {
        .attach = ti_sn_bridge_attach,
        .pre_enable = ti_sn_bridge_pre_enable,
        .enable = ti_sn_bridge_enable,
        .disable = ti_sn_bridge_disable,
        .post_disable = ti_sn_bridge_post_disable,
};

static struct ti_sn_bridge *aux_to_ti_sn_bridge(struct drm_dp_aux *aux)
{
        return container_of(aux, struct ti_sn_bridge, aux);
}

static ssize_t ti_sn_aux_transfer(struct drm_dp_aux *aux,
                                  struct drm_dp_aux_msg *msg)
{
        struct ti_sn_bridge *pdata = aux_to_ti_sn_bridge(aux);
        u32 request = msg->request & ~DP_AUX_I2C_MOT;
        u32 request_val = AUX_CMD_REQ(msg->request);
        u8 *buf = (u8 *)msg->buffer;
        unsigned int val;
        int ret, i;

        if (msg->size > SN_AUX_MAX_PAYLOAD_BYTES)
                return -EINVAL;

        switch (request) {
        case DP_AUX_NATIVE_WRITE:
        case DP_AUX_I2C_WRITE:
        case DP_AUX_NATIVE_READ:
        case DP_AUX_I2C_READ:
                regmap_write(pdata->regmap, SN_AUX_CMD_REG, request_val);
                break;
        default:
                return -EINVAL;
        }

        regmap_write(pdata->regmap, SN_AUX_ADDR_19_16_REG,
                     (msg->address >> 16) & 0xF);
        regmap_write(pdata->regmap, SN_AUX_ADDR_15_8_REG,
                     (msg->address >> 8) & 0xFF);
        regmap_write(pdata->regmap, SN_AUX_ADDR_7_0_REG, msg->address & 0xFF);

        regmap_write(pdata->regmap, SN_AUX_LENGTH_REG, msg->size);

        if (request == DP_AUX_NATIVE_WRITE || request == DP_AUX_I2C_WRITE) {
                for (i = 0; i < msg->size; i++)
                        regmap_write(pdata->regmap, SN_AUX_WDATA_REG(i),
                                     buf[i]);
        }

        regmap_write(pdata->regmap, SN_AUX_CMD_REG, request_val | AUX_CMD_SEND);

        ret = regmap_read_poll_timeout(pdata->regmap, SN_AUX_CMD_REG, val,
                                       !(val & AUX_CMD_SEND), 200,
                                       50 * 1000);
        if (ret)
                return ret;

        ret = regmap_read(pdata->regmap, SN_AUX_CMD_STATUS_REG, &val);
        if (ret)
                return ret;
        else if ((val & AUX_IRQ_STATUS_NAT_I2C_FAIL)
                 || (val & AUX_IRQ_STATUS_AUX_RPLY_TOUT)
                 || (val & AUX_IRQ_STATUS_AUX_SHORT))
                return -ENXIO;

        if (request == DP_AUX_NATIVE_WRITE || request == DP_AUX_I2C_WRITE)
                return msg->size;

        for (i = 0; i < msg->size; i++) {
                unsigned int val;
                ret = regmap_read(pdata->regmap, SN_AUX_RDATA_REG(i),
                                  &val);
                if (ret)
                        return ret;

                WARN_ON(val & ~0xFF);
                buf[i] = (u8)(val & 0xFF);
        }

        return msg->size;
}

static int ti_sn_bridge_parse_dsi_host(struct ti_sn_bridge *pdata)
{
        struct device_node *np = pdata->dev->of_node;

        pdata->host_node = of_graph_get_remote_node(np, 0, 0);

        if (!pdata->host_node) {
                DRM_ERROR("remote dsi host node not found\n");
                return -ENODEV;
        }

        return 0;
}

static int ti_sn_bridge_probe(struct i2c_client *client,
                              const struct i2c_device_id *id)
{
        struct ti_sn_bridge *pdata;
        int ret;

        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
                DRM_ERROR("device doesn't support I2C\n");
                return -ENODEV;
        }

        pdata = devm_kzalloc(&client->dev, sizeof(struct ti_sn_bridge),
                             GFP_KERNEL);
        if (!pdata)
                return -ENOMEM;

        pdata->regmap = devm_regmap_init_i2c(client,
                                             &ti_sn_bridge_regmap_config);
        if (IS_ERR(pdata->regmap)) {
                DRM_ERROR("regmap i2c init failed\n");
                return PTR_ERR(pdata->regmap);
        }

        pdata->dev = &client->dev;

        ret = drm_of_find_panel_or_bridge(pdata->dev->of_node, 1, 0,
                                          &pdata->panel, NULL);
        if (ret) {
                DRM_ERROR("could not find any panel node\n");
                return ret;
        }

        dev_set_drvdata(&client->dev, pdata);

        pdata->enable_gpio = devm_gpiod_get(pdata->dev, "enable",
                                            GPIOD_OUT_LOW);
        if (IS_ERR(pdata->enable_gpio)) {
                DRM_ERROR("failed to get enable gpio from DT\n");
                ret = PTR_ERR(pdata->enable_gpio);
                return ret;
        }

        ret = ti_sn_bridge_parse_regulators(pdata);
        if (ret) {
                DRM_ERROR("failed to parse regulators\n");
                return ret;
        }

        pdata->refclk = devm_clk_get(pdata->dev, "refclk");
        if (IS_ERR(pdata->refclk)) {
                ret = PTR_ERR(pdata->refclk);
                if (ret == -EPROBE_DEFER)
                        return ret;
                DRM_DEBUG_KMS("refclk not found\n");
                pdata->refclk = NULL;
        }

        ret = ti_sn_bridge_parse_dsi_host(pdata);
        if (ret)
                return ret;

        pm_runtime_enable(pdata->dev);

        i2c_set_clientdata(client, pdata);

        pdata->aux.name = "ti-sn65dsi86-aux";
        pdata->aux.dev = pdata->dev;
        pdata->aux.transfer = ti_sn_aux_transfer;
        drm_dp_aux_register(&pdata->aux);

        pdata->bridge.funcs = &ti_sn_bridge_funcs;
        pdata->bridge.of_node = client->dev.of_node;

        drm_bridge_add(&pdata->bridge);

        return 0;
}

static int ti_sn_bridge_remove(struct i2c_client *client)
{
        struct ti_sn_bridge *pdata = i2c_get_clientdata(client);

        if (!pdata)
                return -EINVAL;

        of_node_put(pdata->host_node);

        pm_runtime_disable(pdata->dev);

        if (pdata->dsi) {
                mipi_dsi_detach(pdata->dsi);
                mipi_dsi_device_unregister(pdata->dsi);
        }

        drm_bridge_remove(&pdata->bridge);

        return 0;
}

static struct i2c_device_id ti_sn_bridge_id[] = {
        { "ti,sn65dsi86", 0},
        {},
};
MODULE_DEVICE_TABLE(i2c, ti_sn_bridge_id);

static const struct of_device_id ti_sn_bridge_match_table[] = {
        {.compatible = "ti,sn65dsi86"},
        {},
};
MODULE_DEVICE_TABLE(of, ti_sn_bridge_match_table);

static struct i2c_driver ti_sn_bridge_driver = {
        .driver = {
                .name = "ti_sn65dsi86",
                .of_match_table = ti_sn_bridge_match_table,
                .pm = &ti_sn_bridge_pm_ops,
        },
        .probe = ti_sn_bridge_probe,
        .remove = ti_sn_bridge_remove,
        .id_table = ti_sn_bridge_id,
};
module_i2c_driver(ti_sn_bridge_driver);

MODULE_AUTHOR("Sandeep Panda <spanda@codeaurora.org>");
MODULE_DESCRIPTION("sn65dsi86 DSI to eDP bridge driver");
MODULE_LICENSE("GPL v2");