// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2013 NVIDIA Corporation
 */

#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/host1x.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/regulator/consumer.h>
#include <linux/reset.h>

#include <video/mipi_display.h>

#include <drm/drm_atomic_helper.h>
#include <drm/drm_debugfs.h>
#include <drm/drm_file.h>
#include <drm/drm_mipi_dsi.h>
#include <drm/drm_panel.h>

#include "dc.h"
#include "drm.h"
#include "dsi.h"
#include "mipi-phy.h"
#include "trace.h"

struct tegra_dsi_state {
        struct drm_connector_state base;

        struct mipi_dphy_timing timing;
        unsigned long period;

        unsigned int vrefresh;
        unsigned int lanes;
        unsigned long pclk;
        unsigned long bclk;

        enum tegra_dsi_format format;
        unsigned int mul;
        unsigned int div;
};

static inline struct tegra_dsi_state *
to_dsi_state(struct drm_connector_state *state)
{
        return container_of(state, struct tegra_dsi_state, base);
}

struct tegra_dsi {
        struct host1x_client client;
        struct tegra_output output;
        struct device *dev;

        void __iomem *regs;

        struct reset_control *rst;
        struct clk *clk_parent;
        struct clk *clk_lp;
        struct clk *clk;

        struct drm_info_list *debugfs_files;

        unsigned long flags;
        enum mipi_dsi_pixel_format format;
        unsigned int lanes;

        struct tegra_mipi_device *mipi;
        struct mipi_dsi_host host;

        struct regulator *vdd;

        unsigned int video_fifo_depth;
        unsigned int host_fifo_depth;

        /* for ganged-mode support */
        struct tegra_dsi *master;
        struct tegra_dsi *slave;
};

static inline struct tegra_dsi *
host1x_client_to_dsi(struct host1x_client *client)
{
        return container_of(client, struct tegra_dsi, client);
}

static inline struct tegra_dsi *host_to_tegra(struct mipi_dsi_host *host)
{
        return container_of(host, struct tegra_dsi, host);
}

static inline struct tegra_dsi *to_dsi(struct tegra_output *output)
{
        return container_of(output, struct tegra_dsi, output);
}

static struct tegra_dsi_state *tegra_dsi_get_state(struct tegra_dsi *dsi)
{
        return to_dsi_state(dsi->output.connector.state);
}

static inline u32 tegra_dsi_readl(struct tegra_dsi *dsi, unsigned int offset)
{
        u32 value = readl(dsi->regs + (offset << 2));

        trace_dsi_readl(dsi->dev, offset, value);

        return value;
}

static inline void tegra_dsi_writel(struct tegra_dsi *dsi, u32 value,
                                    unsigned int offset)
{
        trace_dsi_writel(dsi->dev, offset, value);
        writel(value, dsi->regs + (offset << 2));
}

#define DEBUGFS_REG32(_name) { .name = #_name, .offset = _name }

static const struct debugfs_reg32 tegra_dsi_regs[] = {
        DEBUGFS_REG32(DSI_INCR_SYNCPT),
        DEBUGFS_REG32(DSI_INCR_SYNCPT_CONTROL),
        DEBUGFS_REG32(DSI_INCR_SYNCPT_ERROR),
        DEBUGFS_REG32(DSI_CTXSW),
        DEBUGFS_REG32(DSI_RD_DATA),
        DEBUGFS_REG32(DSI_WR_DATA),
        DEBUGFS_REG32(DSI_POWER_CONTROL),
        DEBUGFS_REG32(DSI_INT_ENABLE),
        DEBUGFS_REG32(DSI_INT_STATUS),
        DEBUGFS_REG32(DSI_INT_MASK),
        DEBUGFS_REG32(DSI_HOST_CONTROL),
        DEBUGFS_REG32(DSI_CONTROL),
        DEBUGFS_REG32(DSI_SOL_DELAY),
        DEBUGFS_REG32(DSI_MAX_THRESHOLD),
        DEBUGFS_REG32(DSI_TRIGGER),
        DEBUGFS_REG32(DSI_TX_CRC),
        DEBUGFS_REG32(DSI_STATUS),
        DEBUGFS_REG32(DSI_INIT_SEQ_CONTROL),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_0),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_1),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_2),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_3),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_4),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_5),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_6),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_7),
        DEBUGFS_REG32(DSI_PKT_SEQ_0_LO),
        DEBUGFS_REG32(DSI_PKT_SEQ_0_HI),
        DEBUGFS_REG32(DSI_PKT_SEQ_1_LO),
        DEBUGFS_REG32(DSI_PKT_SEQ_1_HI),
        DEBUGFS_REG32(DSI_PKT_SEQ_2_LO),
        DEBUGFS_REG32(DSI_PKT_SEQ_2_HI),
        DEBUGFS_REG32(DSI_PKT_SEQ_3_LO),
        DEBUGFS_REG32(DSI_PKT_SEQ_3_HI),
        DEBUGFS_REG32(DSI_PKT_SEQ_4_LO),
        DEBUGFS_REG32(DSI_PKT_SEQ_4_HI),
        DEBUGFS_REG32(DSI_PKT_SEQ_5_LO),
        DEBUGFS_REG32(DSI_PKT_SEQ_5_HI),
        DEBUGFS_REG32(DSI_DCS_CMDS),
        DEBUGFS_REG32(DSI_PKT_LEN_0_1),
        DEBUGFS_REG32(DSI_PKT_LEN_2_3),
        DEBUGFS_REG32(DSI_PKT_LEN_4_5),
        DEBUGFS_REG32(DSI_PKT_LEN_6_7),
        DEBUGFS_REG32(DSI_PHY_TIMING_0),
        DEBUGFS_REG32(DSI_PHY_TIMING_1),
        DEBUGFS_REG32(DSI_PHY_TIMING_2),
        DEBUGFS_REG32(DSI_BTA_TIMING),
        DEBUGFS_REG32(DSI_TIMEOUT_0),
        DEBUGFS_REG32(DSI_TIMEOUT_1),
        DEBUGFS_REG32(DSI_TO_TALLY),
        DEBUGFS_REG32(DSI_PAD_CONTROL_0),
        DEBUGFS_REG32(DSI_PAD_CONTROL_CD),
        DEBUGFS_REG32(DSI_PAD_CD_STATUS),
        DEBUGFS_REG32(DSI_VIDEO_MODE_CONTROL),
        DEBUGFS_REG32(DSI_PAD_CONTROL_1),
        DEBUGFS_REG32(DSI_PAD_CONTROL_2),
        DEBUGFS_REG32(DSI_PAD_CONTROL_3),
        DEBUGFS_REG32(DSI_PAD_CONTROL_4),
        DEBUGFS_REG32(DSI_GANGED_MODE_CONTROL),
        DEBUGFS_REG32(DSI_GANGED_MODE_START),
        DEBUGFS_REG32(DSI_GANGED_MODE_SIZE),
        DEBUGFS_REG32(DSI_RAW_DATA_BYTE_COUNT),
        DEBUGFS_REG32(DSI_ULTRA_LOW_POWER_CONTROL),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_8),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_9),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_10),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_11),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_12),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_13),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_14),
        DEBUGFS_REG32(DSI_INIT_SEQ_DATA_15),
};

static int tegra_dsi_show_regs(struct seq_file *s, void *data)
{
        struct drm_info_node *node = s->private;
        struct tegra_dsi *dsi = node->info_ent->data;
        struct drm_crtc *crtc = dsi->output.encoder.crtc;
        struct drm_device *drm = node->minor->dev;
        unsigned int i;
        int err = 0;

        drm_modeset_lock_all(drm);

        if (!crtc || !crtc->state->active) {
                err = -EBUSY;
                goto unlock;
        }

        for (i = 0; i < ARRAY_SIZE(tegra_dsi_regs); i++) {
                unsigned int offset = tegra_dsi_regs[i].offset;

                seq_printf(s, "%-32s %#05x %08x\n", tegra_dsi_regs[i].name,
                           offset, tegra_dsi_readl(dsi, offset));
        }

unlock:
        drm_modeset_unlock_all(drm);
        return err;
}

static struct drm_info_list debugfs_files[] = {
        { "regs", tegra_dsi_show_regs, 0, NULL },
};

static int tegra_dsi_late_register(struct drm_connector *connector)
{
        struct tegra_output *output = connector_to_output(connector);
        unsigned int i, count = ARRAY_SIZE(debugfs_files);
        struct drm_minor *minor = connector->dev->primary;
        struct dentry *root = connector->debugfs_entry;
        struct tegra_dsi *dsi = to_dsi(output);
        int err;

        dsi->debugfs_files = kmemdup(debugfs_files, sizeof(debugfs_files),
                                     GFP_KERNEL);
        if (!dsi->debugfs_files)
                return -ENOMEM;

        for (i = 0; i < count; i++)
                dsi->debugfs_files[i].data = dsi;

        err = drm_debugfs_create_files(dsi->debugfs_files, count, root, minor);
        if (err < 0)
                goto free;

        return 0;

free:
        kfree(dsi->debugfs_files);
        dsi->debugfs_files = NULL;

        return err;
}

static void tegra_dsi_early_unregister(struct drm_connector *connector)
{
        struct tegra_output *output = connector_to_output(connector);
        unsigned int count = ARRAY_SIZE(debugfs_files);
        struct tegra_dsi *dsi = to_dsi(output);

        drm_debugfs_remove_files(dsi->debugfs_files, count,
                                 connector->dev->primary);
        kfree(dsi->debugfs_files);
        dsi->debugfs_files = NULL;
}

#define PKT_ID0(id)     ((((id) & 0x3f) <<  3) | (1 <<  9))
#define PKT_LEN0(len)   (((len) & 0x07) <<  0)
#define PKT_ID1(id)     ((((id) & 0x3f) << 13) | (1 << 19))
#define PKT_LEN1(len)   (((len) & 0x07) << 10)
#define PKT_ID2(id)     ((((id) & 0x3f) << 23) | (1 << 29))
#define PKT_LEN2(len)   (((len) & 0x07) << 20)

#define PKT_LP          (1 << 30)
#define NUM_PKT_SEQ     12

/*
 * non-burst mode with sync pulses
 */
static const u32 pkt_seq_video_non_burst_sync_pulses[NUM_PKT_SEQ] = {
        [ 0] = PKT_ID0(MIPI_DSI_V_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_BLANKING_PACKET) | PKT_LEN1(1) |
               PKT_ID2(MIPI_DSI_H_SYNC_END) | PKT_LEN2(0) |
               PKT_LP,
        [ 1] = 0,
        [ 2] = PKT_ID0(MIPI_DSI_V_SYNC_END) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_BLANKING_PACKET) | PKT_LEN1(1) |
               PKT_ID2(MIPI_DSI_H_SYNC_END) | PKT_LEN2(0) |
               PKT_LP,
        [ 3] = 0,
        [ 4] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_BLANKING_PACKET) | PKT_LEN1(1) |
               PKT_ID2(MIPI_DSI_H_SYNC_END) | PKT_LEN2(0) |
               PKT_LP,
        [ 5] = 0,
        [ 6] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_BLANKING_PACKET) | PKT_LEN1(1) |
               PKT_ID2(MIPI_DSI_H_SYNC_END) | PKT_LEN2(0),
        [ 7] = PKT_ID0(MIPI_DSI_BLANKING_PACKET) | PKT_LEN0(2) |
               PKT_ID1(MIPI_DSI_PACKED_PIXEL_STREAM_24) | PKT_LEN1(3) |
               PKT_ID2(MIPI_DSI_BLANKING_PACKET) | PKT_LEN2(4),
        [ 8] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_BLANKING_PACKET) | PKT_LEN1(1) |
               PKT_ID2(MIPI_DSI_H_SYNC_END) | PKT_LEN2(0) |
               PKT_LP,
        [ 9] = 0,
        [10] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_BLANKING_PACKET) | PKT_LEN1(1) |
               PKT_ID2(MIPI_DSI_H_SYNC_END) | PKT_LEN2(0),
        [11] = PKT_ID0(MIPI_DSI_BLANKING_PACKET) | PKT_LEN0(2) |
               PKT_ID1(MIPI_DSI_PACKED_PIXEL_STREAM_24) | PKT_LEN1(3) |
               PKT_ID2(MIPI_DSI_BLANKING_PACKET) | PKT_LEN2(4),
};

/*
 * non-burst mode with sync events
 */
static const u32 pkt_seq_video_non_burst_sync_events[NUM_PKT_SEQ] = {
        [ 0] = PKT_ID0(MIPI_DSI_V_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_END_OF_TRANSMISSION) | PKT_LEN1(7) |
               PKT_LP,
        [ 1] = 0,
        [ 2] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_END_OF_TRANSMISSION) | PKT_LEN1(7) |
               PKT_LP,
        [ 3] = 0,
        [ 4] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_END_OF_TRANSMISSION) | PKT_LEN1(7) |
               PKT_LP,
        [ 5] = 0,
        [ 6] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_BLANKING_PACKET) | PKT_LEN1(2) |
               PKT_ID2(MIPI_DSI_PACKED_PIXEL_STREAM_24) | PKT_LEN2(3),
        [ 7] = PKT_ID0(MIPI_DSI_BLANKING_PACKET) | PKT_LEN0(4),
        [ 8] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_END_OF_TRANSMISSION) | PKT_LEN1(7) |
               PKT_LP,
        [ 9] = 0,
        [10] = PKT_ID0(MIPI_DSI_H_SYNC_START) | PKT_LEN0(0) |
               PKT_ID1(MIPI_DSI_BLANKING_PACKET) | PKT_LEN1(2) |
               PKT_ID2(MIPI_DSI_PACKED_PIXEL_STREAM_24) | PKT_LEN2(3),
        [11] = PKT_ID0(MIPI_DSI_BLANKING_PACKET) | PKT_LEN0(4),
};

static const u32 pkt_seq_command_mode[NUM_PKT_SEQ] = {
        [ 0] = 0,
        [ 1] = 0,
        [ 2] = 0,
        [ 3] = 0,
        [ 4] = 0,
        [ 5] = 0,
        [ 6] = PKT_ID0(MIPI_DSI_DCS_LONG_WRITE) | PKT_LEN0(3) | PKT_LP,
        [ 7] = 0,
        [ 8] = 0,
        [ 9] = 0,
        [10] = PKT_ID0(MIPI_DSI_DCS_LONG_WRITE) | PKT_LEN0(5) | PKT_LP,
        [11] = 0,
};

static void tegra_dsi_set_phy_timing(struct tegra_dsi *dsi,
                                     unsigned long period,
                                     const struct mipi_dphy_timing *timing)
{
        u32 value;

        value = DSI_TIMING_FIELD(timing->hsexit, period, 1) << 24 |
                DSI_TIMING_FIELD(timing->hstrail, period, 0) << 16 |
                DSI_TIMING_FIELD(timing->hszero, period, 3) << 8 |
                DSI_TIMING_FIELD(timing->hsprepare, period, 1);
        tegra_dsi_writel(dsi, value, DSI_PHY_TIMING_0);

        value = DSI_TIMING_FIELD(timing->clktrail, period, 1) << 24 |
                DSI_TIMING_FIELD(timing->clkpost, period, 1) << 16 |
                DSI_TIMING_FIELD(timing->clkzero, period, 1) << 8 |
                DSI_TIMING_FIELD(timing->lpx, period, 1);
        tegra_dsi_writel(dsi, value, DSI_PHY_TIMING_1);

        value = DSI_TIMING_FIELD(timing->clkprepare, period, 1) << 16 |
                DSI_TIMING_FIELD(timing->clkpre, period, 1) << 8 |
                DSI_TIMING_FIELD(0xff * period, period, 0) << 0;
        tegra_dsi_writel(dsi, value, DSI_PHY_TIMING_2);

        value = DSI_TIMING_FIELD(timing->taget, period, 1) << 16 |
                DSI_TIMING_FIELD(timing->tasure, period, 1) << 8 |
                DSI_TIMING_FIELD(timing->tago, period, 1);
        tegra_dsi_writel(dsi, value, DSI_BTA_TIMING);

        if (dsi->slave)
                tegra_dsi_set_phy_timing(dsi->slave, period, timing);
}

static int tegra_dsi_get_muldiv(enum mipi_dsi_pixel_format format,
                                unsigned int *mulp, unsigned int *divp)
{
        switch (format) {
        case MIPI_DSI_FMT_RGB666_PACKED:
        case MIPI_DSI_FMT_RGB888:
                *mulp = 3;
                *divp = 1;
                break;

        case MIPI_DSI_FMT_RGB565:
                *mulp = 2;
                *divp = 1;
                break;

        case MIPI_DSI_FMT_RGB666:
                *mulp = 9;
                *divp = 4;
                break;

        default:
                return -EINVAL;
        }

        return 0;
}

static int tegra_dsi_get_format(enum mipi_dsi_pixel_format format,
                                enum tegra_dsi_format *fmt)
{
        switch (format) {
        case MIPI_DSI_FMT_RGB888:
                *fmt = TEGRA_DSI_FORMAT_24P;
                break;

        case MIPI_DSI_FMT_RGB666:
                *fmt = TEGRA_DSI_FORMAT_18NP;
                break;

        case MIPI_DSI_FMT_RGB666_PACKED:
                *fmt = TEGRA_DSI_FORMAT_18P;
                break;

        case MIPI_DSI_FMT_RGB565:
                *fmt = TEGRA_DSI_FORMAT_16P;
                break;

        default:
                return -EINVAL;
        }

        return 0;
}

static void tegra_dsi_ganged_enable(struct tegra_dsi *dsi, unsigned int start,
                                    unsigned int size)
{
        u32 value;

        tegra_dsi_writel(dsi, start, DSI_GANGED_MODE_START);
        tegra_dsi_writel(dsi, size << 16 | size, DSI_GANGED_MODE_SIZE);

        value = DSI_GANGED_MODE_CONTROL_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_GANGED_MODE_CONTROL);
}

static void tegra_dsi_enable(struct tegra_dsi *dsi)
{
        u32 value;

        value = tegra_dsi_readl(dsi, DSI_POWER_CONTROL);
        value |= DSI_POWER_CONTROL_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_POWER_CONTROL);

        if (dsi->slave)
                tegra_dsi_enable(dsi->slave);
}

static unsigned int tegra_dsi_get_lanes(struct tegra_dsi *dsi)
{
        if (dsi->master)
                return dsi->master->lanes + dsi->lanes;

        if (dsi->slave)
                return dsi->lanes + dsi->slave->lanes;

        return dsi->lanes;
}

static void tegra_dsi_configure(struct tegra_dsi *dsi, unsigned int pipe,
                                const struct drm_display_mode *mode)
{
        unsigned int hact, hsw, hbp, hfp, i, mul, div;
        struct tegra_dsi_state *state;
        const u32 *pkt_seq;
        u32 value;

        /* XXX: pass in state into this function? */
        if (dsi->master)
                state = tegra_dsi_get_state(dsi->master);
        else
                state = tegra_dsi_get_state(dsi);

        mul = state->mul;
        div = state->div;

        if (dsi->flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) {
                DRM_DEBUG_KMS("Non-burst video mode with sync pulses\n");
                pkt_seq = pkt_seq_video_non_burst_sync_pulses;
        } else if (dsi->flags & MIPI_DSI_MODE_VIDEO) {
                DRM_DEBUG_KMS("Non-burst video mode with sync events\n");
                pkt_seq = pkt_seq_video_non_burst_sync_events;
        } else {
                DRM_DEBUG_KMS("Command mode\n");
                pkt_seq = pkt_seq_command_mode;
        }

        value = DSI_CONTROL_CHANNEL(0) |
                DSI_CONTROL_FORMAT(state->format) |
                DSI_CONTROL_LANES(dsi->lanes - 1) |
                DSI_CONTROL_SOURCE(pipe);
        tegra_dsi_writel(dsi, value, DSI_CONTROL);

        tegra_dsi_writel(dsi, dsi->video_fifo_depth, DSI_MAX_THRESHOLD);

        value = DSI_HOST_CONTROL_HS;
        tegra_dsi_writel(dsi, value, DSI_HOST_CONTROL);

        value = tegra_dsi_readl(dsi, DSI_CONTROL);

        if (dsi->flags & MIPI_DSI_CLOCK_NON_CONTINUOUS)
                value |= DSI_CONTROL_HS_CLK_CTRL;

        value &= ~DSI_CONTROL_TX_TRIG(3);

        /* enable DCS commands for command mode */
        if (dsi->flags & MIPI_DSI_MODE_VIDEO)
                value &= ~DSI_CONTROL_DCS_ENABLE;
        else
                value |= DSI_CONTROL_DCS_ENABLE;

        value |= DSI_CONTROL_VIDEO_ENABLE;
        value &= ~DSI_CONTROL_HOST_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_CONTROL);

        for (i = 0; i < NUM_PKT_SEQ; i++)
                tegra_dsi_writel(dsi, pkt_seq[i], DSI_PKT_SEQ_0_LO + i);

        if (dsi->flags & MIPI_DSI_MODE_VIDEO) {
                /* horizontal active pixels */
                hact = mode->hdisplay * mul / div;

                /* horizontal sync width */
                hsw = (mode->hsync_end - mode->hsync_start) * mul / div;

                /* horizontal back porch */
                hbp = (mode->htotal - mode->hsync_end) * mul / div;

                if ((dsi->flags & MIPI_DSI_MODE_VIDEO_SYNC_PULSE) == 0)
                        hbp += hsw;

                /* horizontal front porch */
                hfp = (mode->hsync_start - mode->hdisplay) * mul / div;

                /* subtract packet overhead */
                hsw -= 10;
                hbp -= 14;
                hfp -= 8;

                tegra_dsi_writel(dsi, hsw << 16 | 0, DSI_PKT_LEN_0_1);
                tegra_dsi_writel(dsi, hact << 16 | hbp, DSI_PKT_LEN_2_3);
                tegra_dsi_writel(dsi, hfp, DSI_PKT_LEN_4_5);
                tegra_dsi_writel(dsi, 0x0f0f << 16, DSI_PKT_LEN_6_7);

                /* set SOL delay (for non-burst mode only) */
                tegra_dsi_writel(dsi, 8 * mul / div, DSI_SOL_DELAY);

                /* TODO: implement ganged mode */
        } else {
                u16 bytes;

                if (dsi->master || dsi->slave) {
                        /*
                         * For ganged mode, assume symmetric left-right mode.
                         */
                        bytes = 1 + (mode->hdisplay / 2) * mul / div;
                } else {
                        /* 1 byte (DCS command) + pixel data */
                        bytes = 1 + mode->hdisplay * mul / div;
                }

                tegra_dsi_writel(dsi, 0, DSI_PKT_LEN_0_1);
                tegra_dsi_writel(dsi, bytes << 16, DSI_PKT_LEN_2_3);
                tegra_dsi_writel(dsi, bytes << 16, DSI_PKT_LEN_4_5);
                tegra_dsi_writel(dsi, 0, DSI_PKT_LEN_6_7);

                value = MIPI_DCS_WRITE_MEMORY_START << 8 |
                        MIPI_DCS_WRITE_MEMORY_CONTINUE;
                tegra_dsi_writel(dsi, value, DSI_DCS_CMDS);

                /* set SOL delay */
                if (dsi->master || dsi->slave) {
                        unsigned long delay, bclk, bclk_ganged;
                        unsigned int lanes = state->lanes;

                        /* SOL to valid, valid to FIFO and FIFO write delay */
                        delay = 4 + 4 + 2;
                        delay = DIV_ROUND_UP(delay * mul, div * lanes);
                        /* FIFO read delay */
                        delay = delay + 6;

                        bclk = DIV_ROUND_UP(mode->htotal * mul, div * lanes);
                        bclk_ganged = DIV_ROUND_UP(bclk * lanes / 2, lanes);
                        value = bclk - bclk_ganged + delay + 20;
                } else {
                        /* TODO: revisit for non-ganged mode */
                        value = 8 * mul / div;
                }

                tegra_dsi_writel(dsi, value, DSI_SOL_DELAY);
        }

        if (dsi->slave) {
                tegra_dsi_configure(dsi->slave, pipe, mode);

                /*
                 * TODO: Support modes other than symmetrical left-right
                 * split.
                 */
                tegra_dsi_ganged_enable(dsi, 0, mode->hdisplay / 2);
                tegra_dsi_ganged_enable(dsi->slave, mode->hdisplay / 2,
                                        mode->hdisplay / 2);
        }
}

static int tegra_dsi_wait_idle(struct tegra_dsi *dsi, unsigned long timeout)
{
        u32 value;

        timeout = jiffies + msecs_to_jiffies(timeout);

        while (time_before(jiffies, timeout)) {
                value = tegra_dsi_readl(dsi, DSI_STATUS);
                if (value & DSI_STATUS_IDLE)
                        return 0;

                usleep_range(1000, 2000);
        }

        return -ETIMEDOUT;
}

static void tegra_dsi_video_disable(struct tegra_dsi *dsi)
{
        u32 value;

        value = tegra_dsi_readl(dsi, DSI_CONTROL);
        value &= ~DSI_CONTROL_VIDEO_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_CONTROL);

        if (dsi->slave)
                tegra_dsi_video_disable(dsi->slave);
}

static void tegra_dsi_ganged_disable(struct tegra_dsi *dsi)
{
        tegra_dsi_writel(dsi, 0, DSI_GANGED_MODE_START);
        tegra_dsi_writel(dsi, 0, DSI_GANGED_MODE_SIZE);
        tegra_dsi_writel(dsi, 0, DSI_GANGED_MODE_CONTROL);
}

static int tegra_dsi_pad_enable(struct tegra_dsi *dsi)
{
        u32 value;

        value = DSI_PAD_CONTROL_VS1_PULLDN(0) | DSI_PAD_CONTROL_VS1_PDIO(0);
        tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_0);

        return 0;
}

static int tegra_dsi_pad_calibrate(struct tegra_dsi *dsi)
{
        u32 value;

        /*
         * XXX Is this still needed? The module reset is deasserted right
         * before this function is called.
         */
        tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_0);
        tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_1);
        tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_2);
        tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_3);
        tegra_dsi_writel(dsi, 0, DSI_PAD_CONTROL_4);

        /* start calibration */
        tegra_dsi_pad_enable(dsi);

        value = DSI_PAD_SLEW_UP(0x7) | DSI_PAD_SLEW_DN(0x7) |
                DSI_PAD_LP_UP(0x1) | DSI_PAD_LP_DN(0x1) |
                DSI_PAD_OUT_CLK(0x0);
        tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_2);

        value = DSI_PAD_PREEMP_PD_CLK(0x3) | DSI_PAD_PREEMP_PU_CLK(0x3) |
                DSI_PAD_PREEMP_PD(0x03) | DSI_PAD_PREEMP_PU(0x3);
        tegra_dsi_writel(dsi, value, DSI_PAD_CONTROL_3);

        return tegra_mipi_calibrate(dsi->mipi);
}

static void tegra_dsi_set_timeout(struct tegra_dsi *dsi, unsigned long bclk,
                                  unsigned int vrefresh)
{
        unsigned int timeout;
        u32 value;

        /* one frame high-speed transmission timeout */
        timeout = (bclk / vrefresh) / 512;
        value = DSI_TIMEOUT_LRX(0x2000) | DSI_TIMEOUT_HTX(timeout);
        tegra_dsi_writel(dsi, value, DSI_TIMEOUT_0);

        /* 2 ms peripheral timeout for panel */
        timeout = 2 * bclk / 512 * 1000;
        value = DSI_TIMEOUT_PR(timeout) | DSI_TIMEOUT_TA(0x2000);
        tegra_dsi_writel(dsi, value, DSI_TIMEOUT_1);

        value = DSI_TALLY_TA(0) | DSI_TALLY_LRX(0) | DSI_TALLY_HTX(0);
        tegra_dsi_writel(dsi, value, DSI_TO_TALLY);

        if (dsi->slave)
                tegra_dsi_set_timeout(dsi->slave, bclk, vrefresh);
}

static void tegra_dsi_disable(struct tegra_dsi *dsi)
{
        u32 value;

        if (dsi->slave) {
                tegra_dsi_ganged_disable(dsi->slave);
                tegra_dsi_ganged_disable(dsi);
        }

        value = tegra_dsi_readl(dsi, DSI_POWER_CONTROL);
        value &= ~DSI_POWER_CONTROL_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_POWER_CONTROL);

        if (dsi->slave)
                tegra_dsi_disable(dsi->slave);

        usleep_range(5000, 10000);
}

static void tegra_dsi_soft_reset(struct tegra_dsi *dsi)
{
        u32 value;

        value = tegra_dsi_readl(dsi, DSI_POWER_CONTROL);
        value &= ~DSI_POWER_CONTROL_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_POWER_CONTROL);

        usleep_range(300, 1000);

        value = tegra_dsi_readl(dsi, DSI_POWER_CONTROL);
        value |= DSI_POWER_CONTROL_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_POWER_CONTROL);

        usleep_range(300, 1000);

        value = tegra_dsi_readl(dsi, DSI_TRIGGER);
        if (value)
                tegra_dsi_writel(dsi, 0, DSI_TRIGGER);

        if (dsi->slave)
                tegra_dsi_soft_reset(dsi->slave);
}

static void tegra_dsi_connector_reset(struct drm_connector *connector)
{
        struct tegra_dsi_state *state = kzalloc(sizeof(*state), GFP_KERNEL);

        if (!state)
                return;

        if (connector->state) {
                __drm_atomic_helper_connector_destroy_state(connector->state);
                kfree(connector->state);
        }

        __drm_atomic_helper_connector_reset(connector, &state->base);
}

static struct drm_connector_state *
tegra_dsi_connector_duplicate_state(struct drm_connector *connector)
{
        struct tegra_dsi_state *state = to_dsi_state(connector->state);
        struct tegra_dsi_state *copy;

        copy = kmemdup(state, sizeof(*state), GFP_KERNEL);
        if (!copy)
                return NULL;

        __drm_atomic_helper_connector_duplicate_state(connector,
                                                      &copy->base);

        return &copy->base;
}

static const struct drm_connector_funcs tegra_dsi_connector_funcs = {
        .reset = tegra_dsi_connector_reset,
        .detect = tegra_output_connector_detect,
        .fill_modes = drm_helper_probe_single_connector_modes,
        .destroy = tegra_output_connector_destroy,
        .atomic_duplicate_state = tegra_dsi_connector_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
        .late_register = tegra_dsi_late_register,
        .early_unregister = tegra_dsi_early_unregister,
};

static enum drm_mode_status
tegra_dsi_connector_mode_valid(struct drm_connector *connector,
                               struct drm_display_mode *mode)
{
        return MODE_OK;
}

static const struct drm_connector_helper_funcs tegra_dsi_connector_helper_funcs = {
        .get_modes = tegra_output_connector_get_modes,
        .mode_valid = tegra_dsi_connector_mode_valid,
};

static const struct drm_encoder_funcs tegra_dsi_encoder_funcs = {
        .destroy = tegra_output_encoder_destroy,
};

static void tegra_dsi_unprepare(struct tegra_dsi *dsi)
{
        int err;

        if (dsi->slave)
                tegra_dsi_unprepare(dsi->slave);

        err = tegra_mipi_disable(dsi->mipi);
        if (err < 0)
                dev_err(dsi->dev, "failed to disable MIPI calibration: %d\n",
                        err);

        err = host1x_client_suspend(&dsi->client);
        if (err < 0)
                dev_err(dsi->dev, "failed to suspend: %d\n", err);
}

static void tegra_dsi_encoder_disable(struct drm_encoder *encoder)
{
        struct tegra_output *output = encoder_to_output(encoder);
        struct tegra_dc *dc = to_tegra_dc(encoder->crtc);
        struct tegra_dsi *dsi = to_dsi(output);
        u32 value;
        int err;

        if (output->panel)
                drm_panel_disable(output->panel);

        tegra_dsi_video_disable(dsi);

        /*
         * The following accesses registers of the display controller, so make
         * sure it's only executed when the output is attached to one.
         */
        if (dc) {
                value = tegra_dc_readl(dc, DC_DISP_DISP_WIN_OPTIONS);
                value &= ~DSI_ENABLE;
                tegra_dc_writel(dc, value, DC_DISP_DISP_WIN_OPTIONS);

                tegra_dc_commit(dc);
        }

        err = tegra_dsi_wait_idle(dsi, 100);
        if (err < 0)
                dev_dbg(dsi->dev, "failed to idle DSI: %d\n", err);

        tegra_dsi_soft_reset(dsi);

        if (output->panel)
                drm_panel_unprepare(output->panel);

        tegra_dsi_disable(dsi);

        tegra_dsi_unprepare(dsi);
}

static int tegra_dsi_prepare(struct tegra_dsi *dsi)
{
        int err;

        err = host1x_client_resume(&dsi->client);
        if (err < 0) {
                dev_err(dsi->dev, "failed to resume: %d\n", err);
                return err;
        }

        err = tegra_mipi_enable(dsi->mipi);
        if (err < 0)
                dev_err(dsi->dev, "failed to enable MIPI calibration: %d\n",
                        err);

        err = tegra_dsi_pad_calibrate(dsi);
        if (err < 0)
                dev_err(dsi->dev, "MIPI calibration failed: %d\n", err);

        if (dsi->slave)
                tegra_dsi_prepare(dsi->slave);

        return 0;
}

static void tegra_dsi_encoder_enable(struct drm_encoder *encoder)
{
        struct drm_display_mode *mode = &encoder->crtc->state->adjusted_mode;
        struct tegra_output *output = encoder_to_output(encoder);
        struct tegra_dc *dc = to_tegra_dc(encoder->crtc);
        struct tegra_dsi *dsi = to_dsi(output);
        struct tegra_dsi_state *state;
        u32 value;
        int err;

        err = tegra_dsi_prepare(dsi);
        if (err < 0) {
                dev_err(dsi->dev, "failed to prepare: %d\n", err);
                return;
        }

        state = tegra_dsi_get_state(dsi);

        tegra_dsi_set_timeout(dsi, state->bclk, state->vrefresh);

        /*
         * The D-PHY timing fields are expressed in byte-clock cycles, so
         * multiply the period by 8.
         */
        tegra_dsi_set_phy_timing(dsi, state->period * 8, &state->timing);

        if (output->panel)
                drm_panel_prepare(output->panel);

        tegra_dsi_configure(dsi, dc->pipe, mode);

        /* enable display controller */
        value = tegra_dc_readl(dc, DC_DISP_DISP_WIN_OPTIONS);
        value |= DSI_ENABLE;
        tegra_dc_writel(dc, value, DC_DISP_DISP_WIN_OPTIONS);

        tegra_dc_commit(dc);

        /* enable DSI controller */
        tegra_dsi_enable(dsi);

        if (output->panel)
                drm_panel_enable(output->panel);
}

static int
tegra_dsi_encoder_atomic_check(struct drm_encoder *encoder,
                               struct drm_crtc_state *crtc_state,
                               struct drm_connector_state *conn_state)
{
        struct tegra_output *output = encoder_to_output(encoder);
        struct tegra_dsi_state *state = to_dsi_state(conn_state);
        struct tegra_dc *dc = to_tegra_dc(conn_state->crtc);
        struct tegra_dsi *dsi = to_dsi(output);
        unsigned int scdiv;
        unsigned long plld;
        int err;

        state->pclk = crtc_state->mode.clock * 1000;

        err = tegra_dsi_get_muldiv(dsi->format, &state->mul, &state->div);
        if (err < 0)
                return err;

        state->lanes = tegra_dsi_get_lanes(dsi);

        err = tegra_dsi_get_format(dsi->format, &state->format);
        if (err < 0)
                return err;

        state->vrefresh = drm_mode_vrefresh(&crtc_state->mode);

        /* compute byte clock */
        state->bclk = (state->pclk * state->mul) / (state->div * state->lanes);

        DRM_DEBUG_KMS("mul: %u, div: %u, lanes: %u\n", state->mul, state->div,
                      state->lanes);
        DRM_DEBUG_KMS("format: %u, vrefresh: %u\n", state->format,
                      state->vrefresh);
        DRM_DEBUG_KMS("bclk: %lu\n", state->bclk);

        /*
         * Compute bit clock and round up to the next MHz.
         */
        plld = DIV_ROUND_UP(state->bclk * 8, USEC_PER_SEC) * USEC_PER_SEC;
        state->period = DIV_ROUND_CLOSEST(NSEC_PER_SEC, plld);

        err = mipi_dphy_timing_get_default(&state->timing, state->period);
        if (err < 0)

                return err;

        err = mipi_dphy_timing_validate(&state->timing, state->period);
        if (err < 0) {
                dev_err(dsi->dev, "failed to validate D-PHY timing: %d\n", err);
                return err;
        }

        /*
         * We divide the frequency by two here, but we make up for that by
         * setting the shift clock divider (further below) to half of the
         * correct value.
         */
        plld /= 2;

        /*
         * Derive pixel clock from bit clock using the shift clock divider.
         * Note that this is only half of what we would expect, but we need
         * that to make up for the fact that we divided the bit clock by a
         * factor of two above.
         *
         * It's not clear exactly why this is necessary, but the display is
         * not working properly otherwise. Perhaps the PLLs cannot generate
         * frequencies sufficiently high.
         */
        scdiv = ((8 * state->mul) / (state->div * state->lanes)) - 2;

        err = tegra_dc_state_setup_clock(dc, crtc_state, dsi->clk_parent,
                                         plld, scdiv);
        if (err < 0) {
                dev_err(output->dev, "failed to setup CRTC state: %d\n", err);
                return err;
        }

        return err;
}

static const struct drm_encoder_helper_funcs tegra_dsi_encoder_helper_funcs = {
        .disable = tegra_dsi_encoder_disable,
        .enable = tegra_dsi_encoder_enable,
        .atomic_check = tegra_dsi_encoder_atomic_check,
};

static int tegra_dsi_init(struct host1x_client *client)
{
        struct drm_device *drm = dev_get_drvdata(client->host);
        struct tegra_dsi *dsi = host1x_client_to_dsi(client);
        int err;

        /* Gangsters must not register their own outputs. */
        if (!dsi->master) {
                dsi->output.dev = client->dev;

                drm_connector_init(drm, &dsi->output.connector,
                                   &tegra_dsi_connector_funcs,
                                   DRM_MODE_CONNECTOR_DSI);
                drm_connector_helper_add(&dsi->output.connector,
                                         &tegra_dsi_connector_helper_funcs);
                dsi->output.connector.dpms = DRM_MODE_DPMS_OFF;

                drm_encoder_init(drm, &dsi->output.encoder,
                                 &tegra_dsi_encoder_funcs,
                                 DRM_MODE_ENCODER_DSI, NULL);
                drm_encoder_helper_add(&dsi->output.encoder,
                                       &tegra_dsi_encoder_helper_funcs);

                drm_connector_attach_encoder(&dsi->output.connector,
                                                  &dsi->output.encoder);
                drm_connector_register(&dsi->output.connector);

                err = tegra_output_init(drm, &dsi->output);
                if (err < 0)
                        dev_err(dsi->dev, "failed to initialize output: %d\n",
                                err);

                dsi->output.encoder.possible_crtcs = 0x3;
        }

        return 0;
}

static int tegra_dsi_exit(struct host1x_client *client)
{
        struct tegra_dsi *dsi = host1x_client_to_dsi(client);

        tegra_output_exit(&dsi->output);

        return 0;
}

static int tegra_dsi_runtime_suspend(struct host1x_client *client)
{
        struct tegra_dsi *dsi = host1x_client_to_dsi(client);
        struct device *dev = client->dev;
        int err;

        if (dsi->rst) {
                err = reset_control_assert(dsi->rst);
                if (err < 0) {
                        dev_err(dev, "failed to assert reset: %d\n", err);
                        return err;
                }
        }

        usleep_range(1000, 2000);

        clk_disable_unprepare(dsi->clk_lp);
        clk_disable_unprepare(dsi->clk);

        regulator_disable(dsi->vdd);
        pm_runtime_put_sync(dev);

        return 0;
}

static int tegra_dsi_runtime_resume(struct host1x_client *client)
{
        struct tegra_dsi *dsi = host1x_client_to_dsi(client);
        struct device *dev = client->dev;
        int err;

        err = pm_runtime_get_sync(dev);
        if (err < 0) {
                dev_err(dev, "failed to get runtime PM: %d\n", err);
                return err;
        }

        err = regulator_enable(dsi->vdd);
        if (err < 0) {
                dev_err(dev, "failed to enable VDD supply: %d\n", err);
                goto put_rpm;
        }

        err = clk_prepare_enable(dsi->clk);
        if (err < 0) {
                dev_err(dev, "cannot enable DSI clock: %d\n", err);
                goto disable_vdd;
        }

        err = clk_prepare_enable(dsi->clk_lp);
        if (err < 0) {
                dev_err(dev, "cannot enable low-power clock: %d\n", err);
                goto disable_clk;
        }

        usleep_range(1000, 2000);

        if (dsi->rst) {
                err = reset_control_deassert(dsi->rst);
                if (err < 0) {
                        dev_err(dev, "cannot assert reset: %d\n", err);
                        goto disable_clk_lp;
                }
        }

        return 0;

disable_clk_lp:
        clk_disable_unprepare(dsi->clk_lp);
disable_clk:
        clk_disable_unprepare(dsi->clk);
disable_vdd:
        regulator_disable(dsi->vdd);
put_rpm:
        pm_runtime_put_sync(dev);
        return err;
}

static const struct host1x_client_ops dsi_client_ops = {
        .init = tegra_dsi_init,
        .exit = tegra_dsi_exit,
        .suspend = tegra_dsi_runtime_suspend,
        .resume = tegra_dsi_runtime_resume,
};

static int tegra_dsi_setup_clocks(struct tegra_dsi *dsi)
{
        struct clk *parent;
        int err;

        parent = clk_get_parent(dsi->clk);
        if (!parent)
                return -EINVAL;

        err = clk_set_parent(parent, dsi->clk_parent);
        if (err < 0)
                return err;

        return 0;
}

static const char * const error_report[16] = {
        "SoT Error",
        "SoT Sync Error",
        "EoT Sync Error",
        "Escape Mode Entry Command Error",
        "Low-Power Transmit Sync Error",
        "Peripheral Timeout Error",
        "False Control Error",
        "Contention Detected",
        "ECC Error, single-bit",
        "ECC Error, multi-bit",
        "Checksum Error",
        "DSI Data Type Not Recognized",
        "DSI VC ID Invalid",
        "Invalid Transmission Length",
        "Reserved",
        "DSI Protocol Violation",
};

static ssize_t tegra_dsi_read_response(struct tegra_dsi *dsi,
                                       const struct mipi_dsi_msg *msg,
                                       size_t count)
{
        u8 *rx = msg->rx_buf;
        unsigned int i, j, k;
        size_t size = 0;
        u16 errors;
        u32 value;

        /* read and parse packet header */
        value = tegra_dsi_readl(dsi, DSI_RD_DATA);

        switch (value & 0x3f) {
        case MIPI_DSI_RX_ACKNOWLEDGE_AND_ERROR_REPORT:
                errors = (value >> 8) & 0xffff;
                dev_dbg(dsi->dev, "Acknowledge and error report: %04x\n",
                        errors);
                for (i = 0; i < ARRAY_SIZE(error_report); i++)
                        if (errors & BIT(i))
                                dev_dbg(dsi->dev, "  %2u: %s\n", i,
                                        error_report[i]);
                break;

        case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_1BYTE:
                rx[0] = (value >> 8) & 0xff;
                size = 1;
                break;

        case MIPI_DSI_RX_DCS_SHORT_READ_RESPONSE_2BYTE:
                rx[0] = (value >>  8) & 0xff;
                rx[1] = (value >> 16) & 0xff;
                size = 2;
                break;

        case MIPI_DSI_RX_DCS_LONG_READ_RESPONSE:
                size = ((value >> 8) & 0xff00) | ((value >> 8) & 0xff);
                break;

        case MIPI_DSI_RX_GENERIC_LONG_READ_RESPONSE:
                size = ((value >> 8) & 0xff00) | ((value >> 8) & 0xff);
                break;

        default:
                dev_err(dsi->dev, "unhandled response type: %02x\n",
                        value & 0x3f);
                return -EPROTO;
        }

        size = min(size, msg->rx_len);

        if (msg->rx_buf && size > 0) {
                for (i = 0, j = 0; i < count - 1; i++, j += 4) {
                        u8 *rx = msg->rx_buf + j;

                        value = tegra_dsi_readl(dsi, DSI_RD_DATA);

                        for (k = 0; k < 4 && (j + k) < msg->rx_len; k++)
                                rx[j + k] = (value >> (k << 3)) & 0xff;
                }
        }

        return size;
}

static int tegra_dsi_transmit(struct tegra_dsi *dsi, unsigned long timeout)
{
        tegra_dsi_writel(dsi, DSI_TRIGGER_HOST, DSI_TRIGGER);

        timeout = jiffies + msecs_to_jiffies(timeout);

        while (time_before(jiffies, timeout)) {
                u32 value = tegra_dsi_readl(dsi, DSI_TRIGGER);
                if ((value & DSI_TRIGGER_HOST) == 0)
                        return 0;

                usleep_range(1000, 2000);
        }

        DRM_DEBUG_KMS("timeout waiting for transmission to complete\n");
        return -ETIMEDOUT;
}

static int tegra_dsi_wait_for_response(struct tegra_dsi *dsi,
                                       unsigned long timeout)
{
        timeout = jiffies + msecs_to_jiffies(250);

        while (time_before(jiffies, timeout)) {
                u32 value = tegra_dsi_readl(dsi, DSI_STATUS);
                u8 count = value & 0x1f;

                if (count > 0)
                        return count;

                usleep_range(1000, 2000);
        }

        DRM_DEBUG_KMS("peripheral returned no data\n");
        return -ETIMEDOUT;
}

static void tegra_dsi_writesl(struct tegra_dsi *dsi, unsigned long offset,
                              const void *buffer, size_t size)
{
        const u8 *buf = buffer;
        size_t i, j;
        u32 value;

        for (j = 0; j < size; j += 4) {
                value = 0;

                for (i = 0; i < 4 && j + i < size; i++)
                        value |= buf[j + i] << (i << 3);

                tegra_dsi_writel(dsi, value, DSI_WR_DATA);
        }
}

static ssize_t tegra_dsi_host_transfer(struct mipi_dsi_host *host,
                                       const struct mipi_dsi_msg *msg)
{
        struct tegra_dsi *dsi = host_to_tegra(host);
        struct mipi_dsi_packet packet;
        const u8 *header;
        size_t count;
        ssize_t err;
        u32 value;

        err = mipi_dsi_create_packet(&packet, msg);
        if (err < 0)
                return err;

        header = packet.header;

        /* maximum FIFO depth is 1920 words */
        if (packet.size > dsi->video_fifo_depth * 4)
                return -ENOSPC;

        /* reset underflow/overflow flags */
        value = tegra_dsi_readl(dsi, DSI_STATUS);
        if (value & (DSI_STATUS_UNDERFLOW | DSI_STATUS_OVERFLOW)) {
                value = DSI_HOST_CONTROL_FIFO_RESET;
                tegra_dsi_writel(dsi, value, DSI_HOST_CONTROL);
                usleep_range(10, 20);
        }

        value = tegra_dsi_readl(dsi, DSI_POWER_CONTROL);
        value |= DSI_POWER_CONTROL_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_POWER_CONTROL);

        usleep_range(5000, 10000);

        value = DSI_HOST_CONTROL_CRC_RESET | DSI_HOST_CONTROL_TX_TRIG_HOST |
                DSI_HOST_CONTROL_CS | DSI_HOST_CONTROL_ECC;

        if ((msg->flags & MIPI_DSI_MSG_USE_LPM) == 0)
                value |= DSI_HOST_CONTROL_HS;

        /*
         * The host FIFO has a maximum of 64 words, so larger transmissions
         * need to use the video FIFO.
         */
        if (packet.size > dsi->host_fifo_depth * 4)
                value |= DSI_HOST_CONTROL_FIFO_SEL;

        tegra_dsi_writel(dsi, value, DSI_HOST_CONTROL);

        /*
         * For reads and messages with explicitly requested ACK, generate a
         * BTA sequence after the transmission of the packet.
         */
        if ((msg->flags & MIPI_DSI_MSG_REQ_ACK) ||
            (msg->rx_buf && msg->rx_len > 0)) {
                value = tegra_dsi_readl(dsi, DSI_HOST_CONTROL);
                value |= DSI_HOST_CONTROL_PKT_BTA;
                tegra_dsi_writel(dsi, value, DSI_HOST_CONTROL);
        }

        value = DSI_CONTROL_LANES(0) | DSI_CONTROL_HOST_ENABLE;
        tegra_dsi_writel(dsi, value, DSI_CONTROL);

        /* write packet header, ECC is generated by hardware */
        value = header[2] << 16 | header[1] << 8 | header[0];
        tegra_dsi_writel(dsi, value, DSI_WR_DATA);

        /* write payload (if any) */
        if (packet.payload_length > 0)
                tegra_dsi_writesl(dsi, DSI_WR_DATA, packet.payload,
                                  packet.payload_length);

        err = tegra_dsi_transmit(dsi, 250);
        if (err < 0)
                return err;

        if ((msg->flags & MIPI_DSI_MSG_REQ_ACK) ||
            (msg->rx_buf && msg->rx_len > 0)) {
                err = tegra_dsi_wait_for_response(dsi, 250);
                if (err < 0)
                        return err;

                count = err;

                value = tegra_dsi_readl(dsi, DSI_RD_DATA);
                switch (value) {
                case 0x84:
                        /*
                        dev_dbg(dsi->dev, "ACK\n");
                        */
                        break;

                case 0x87:
                        /*
                        dev_dbg(dsi->dev, "ESCAPE\n");
                        */
                        break;

                default:
                        dev_err(dsi->dev, "unknown status: %08x\n", value);
                        break;
                }

                if (count > 1) {
                        err = tegra_dsi_read_response(dsi, msg, count);
                        if (err < 0)
                                dev_err(dsi->dev,
                                        "failed to parse response: %zd\n",
                                        err);
                        else {
                                /*
                                 * For read commands, return the number of
                                 * bytes returned by the peripheral.
                                 */
                                count = err;
                        }
                }
        } else {
                /*
                 * For write commands, we have transmitted the 4-byte header
                 * plus the variable-length payload.
                 */
                count = 4 + packet.payload_length;
        }

        return count;
}

static int tegra_dsi_ganged_setup(struct tegra_dsi *dsi)
{
        struct clk *parent;
        int err;

        /* make sure both DSI controllers share the same PLL */
        parent = clk_get_parent(dsi->slave->clk);
        if (!parent)
                return -EINVAL;

        err = clk_set_parent(parent, dsi->clk_parent);
        if (err < 0)
                return err;

        return 0;
}

static int tegra_dsi_host_attach(struct mipi_dsi_host *host,
                                 struct mipi_dsi_device *device)
{
        struct tegra_dsi *dsi = host_to_tegra(host);

        dsi->flags = device->mode_flags;
        dsi->format = device->format;
        dsi->lanes = device->lanes;

        if (dsi->slave) {
                int err;

                dev_dbg(dsi->dev, "attaching dual-channel device %s\n",
                        dev_name(&device->dev));

                err = tegra_dsi_ganged_setup(dsi);
                if (err < 0) {
                        dev_err(dsi->dev, "failed to set up ganged mode: %d\n",
                                err);
                        return err;
                }
        }

        /*
         * Slaves don't have a panel associated with them, so they provide
         * merely the second channel.
         */
        if (!dsi->master) {
                struct tegra_output *output = &dsi->output;

                output->panel = of_drm_find_panel(device->dev.of_node);
                if (IS_ERR(output->panel))
                        output->panel = NULL;

                if (output->panel && output->connector.dev) {
                        drm_panel_attach(output->panel, &output->connector);
                        drm_helper_hpd_irq_event(output->connector.dev);
                }
        }

        return 0;
}

static int tegra_dsi_host_detach(struct mipi_dsi_host *host,
                                 struct mipi_dsi_device *device)
{
        struct tegra_dsi *dsi = host_to_tegra(host);
        struct tegra_output *output = &dsi->output;

        if (output->panel && &device->dev == output->panel->dev) {
                output->panel = NULL;

                if (output->connector.dev)
                        drm_helper_hpd_irq_event(output->connector.dev);
        }

        return 0;
}

static const struct mipi_dsi_host_ops tegra_dsi_host_ops = {
        .attach = tegra_dsi_host_attach,
        .detach = tegra_dsi_host_detach,
        .transfer = tegra_dsi_host_transfer,
};

static int tegra_dsi_ganged_probe(struct tegra_dsi *dsi)
{
        struct device_node *np;

        np = of_parse_phandle(dsi->dev->of_node, "nvidia,ganged-mode", 0);
        if (np) {
                struct platform_device *gangster = of_find_device_by_node(np);

                dsi->slave = platform_get_drvdata(gangster);
                of_node_put(np);

                if (!dsi->slave)
                        return -EPROBE_DEFER;

                dsi->slave->master = dsi;
        }

        return 0;
}

static int tegra_dsi_probe(struct platform_device *pdev)
{
        struct tegra_dsi *dsi;
        struct resource *regs;
        int err;

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

        dsi->output.dev = dsi->dev = &pdev->dev;
        dsi->video_fifo_depth = 1920;
        dsi->host_fifo_depth = 64;

        err = tegra_dsi_ganged_probe(dsi);
        if (err < 0)
                return err;

        err = tegra_output_probe(&dsi->output);
        if (err < 0)
                return err;

        dsi->output.connector.polled = DRM_CONNECTOR_POLL_HPD;

        /*
         * Assume these values by default. When a DSI peripheral driver
         * attaches to the DSI host, the parameters will be taken from
         * the attached device.
         */
        dsi->flags = MIPI_DSI_MODE_VIDEO;
        dsi->format = MIPI_DSI_FMT_RGB888;
        dsi->lanes = 4;

        if (!pdev->dev.pm_domain) {
                dsi->rst = devm_reset_control_get(&pdev->dev, "dsi");
                if (IS_ERR(dsi->rst))
                        return PTR_ERR(dsi->rst);
        }

        dsi->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(dsi->clk)) {
                dev_err(&pdev->dev, "cannot get DSI clock\n");
                return PTR_ERR(dsi->clk);
        }

        dsi->clk_lp = devm_clk_get(&pdev->dev, "lp");
        if (IS_ERR(dsi->clk_lp)) {
                dev_err(&pdev->dev, "cannot get low-power clock\n");
                return PTR_ERR(dsi->clk_lp);
        }

        dsi->clk_parent = devm_clk_get(&pdev->dev, "parent");
        if (IS_ERR(dsi->clk_parent)) {
                dev_err(&pdev->dev, "cannot get parent clock\n");
                return PTR_ERR(dsi->clk_parent);
        }

        dsi->vdd = devm_regulator_get(&pdev->dev, "avdd-dsi-csi");
        if (IS_ERR(dsi->vdd)) {
                dev_err(&pdev->dev, "cannot get VDD supply\n");
                return PTR_ERR(dsi->vdd);
        }

        err = tegra_dsi_setup_clocks(dsi);
        if (err < 0) {
                dev_err(&pdev->dev, "cannot setup clocks\n");
                return err;
        }

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        dsi->regs = devm_ioremap_resource(&pdev->dev, regs);
        if (IS_ERR(dsi->regs))
                return PTR_ERR(dsi->regs);

        dsi->mipi = tegra_mipi_request(&pdev->dev);
        if (IS_ERR(dsi->mipi))
                return PTR_ERR(dsi->mipi);

        dsi->host.ops = &tegra_dsi_host_ops;
        dsi->host.dev = &pdev->dev;

        err = mipi_dsi_host_register(&dsi->host);
        if (err < 0) {
                dev_err(&pdev->dev, "failed to register DSI host: %d\n", err);
                goto mipi_free;
        }

        platform_set_drvdata(pdev, dsi);
        pm_runtime_enable(&pdev->dev);

        INIT_LIST_HEAD(&dsi->client.list);
        dsi->client.ops = &dsi_client_ops;
        dsi->client.dev = &pdev->dev;

        err = host1x_client_register(&dsi->client);
        if (err < 0) {
                dev_err(&pdev->dev, "failed to register host1x client: %d\n",
                        err);
                goto unregister;
        }

        return 0;

unregister:
        mipi_dsi_host_unregister(&dsi->host);
mipi_free:
        tegra_mipi_free(dsi->mipi);
        return err;
}

static int tegra_dsi_remove(struct platform_device *pdev)
{
        struct tegra_dsi *dsi = platform_get_drvdata(pdev);
        int err;

        pm_runtime_disable(&pdev->dev);

        err = host1x_client_unregister(&dsi->client);
        if (err < 0) {
                dev_err(&pdev->dev, "failed to unregister host1x client: %d\n",
                        err);
                return err;
        }

        tegra_output_remove(&dsi->output);

        mipi_dsi_host_unregister(&dsi->host);
        tegra_mipi_free(dsi->mipi);

        return 0;
}

static const struct of_device_id tegra_dsi_of_match[] = {
        { .compatible = "nvidia,tegra210-dsi", },
        { .compatible = "nvidia,tegra132-dsi", },
        { .compatible = "nvidia,tegra124-dsi", },
        { .compatible = "nvidia,tegra114-dsi", },
        { },
};
MODULE_DEVICE_TABLE(of, tegra_dsi_of_match);

struct platform_driver tegra_dsi_driver = {
        .driver = {
                .name = "tegra-dsi",
                .of_match_table = tegra_dsi_of_match,
        },
        .probe = tegra_dsi_probe,
        .remove = tegra_dsi_remove,
};