// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) STMicroelectronics SA 2017
 *
 * Authors: Philippe Cornu <philippe.cornu@st.com>
 *          Yannick Fertre <yannick.fertre@st.com>
 *          Fabien Dessenne <fabien.dessenne@st.com>
 *          Mickael Reulier <mickael.reulier@st.com>
 */

#include <linux/clk.h>
#include <linux/component.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_address.h>
#include <linux/of_graph.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <linux/reset.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_bridge.h>
#include <drm/drm_device.h>
#include <drm/drm_fb_cma_helper.h>
#include <drm/drm_fourcc.h>
#include <drm/drm_gem_atomic_helper.h>
#include <drm/drm_gem_cma_helper.h>
#include <drm/drm_of.h>
#include <drm/drm_plane_helper.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_simple_kms_helper.h>
#include <drm/drm_vblank.h>

#include <video/videomode.h>

#include "ltdc.h"

#define NB_CRTC 1
#define CRTC_MASK GENMASK(NB_CRTC - 1, 0)

#define MAX_IRQ 4

#define HWVER_10200 0x010200
#define HWVER_10300 0x010300
#define HWVER_20101 0x020101

/*
 * The address of some registers depends on the HW version: such registers have
 * an extra offset specified with reg_ofs.
 */
#define REG_OFS_NONE    0
#define REG_OFS_4       4               /* Insertion of "Layer Conf. 2" reg */
#define REG_OFS         (ldev->caps.reg_ofs)
#define LAY_OFS         0x80            /* Register Offset between 2 layers */

/* Global register offsets */
#define LTDC_IDR        0x0000          /* IDentification */
#define LTDC_LCR        0x0004          /* Layer Count */
#define LTDC_SSCR       0x0008          /* Synchronization Size Configuration */
#define LTDC_BPCR       0x000C          /* Back Porch Configuration */
#define LTDC_AWCR       0x0010          /* Active Width Configuration */
#define LTDC_TWCR       0x0014          /* Total Width Configuration */
#define LTDC_GCR        0x0018          /* Global Control */
#define LTDC_GC1R       0x001C          /* Global Configuration 1 */
#define LTDC_GC2R       0x0020          /* Global Configuration 2 */
#define LTDC_SRCR       0x0024          /* Shadow Reload Configuration */
#define LTDC_GACR       0x0028          /* GAmma Correction */
#define LTDC_BCCR       0x002C          /* Background Color Configuration */
#define LTDC_IER        0x0034          /* Interrupt Enable */
#define LTDC_ISR        0x0038          /* Interrupt Status */
#define LTDC_ICR        0x003C          /* Interrupt Clear */
#define LTDC_LIPCR      0x0040          /* Line Interrupt Position Conf. */
#define LTDC_CPSR       0x0044          /* Current Position Status */
#define LTDC_CDSR       0x0048          /* Current Display Status */

/* Layer register offsets */
#define LTDC_L1LC1R     (0x80)          /* L1 Layer Configuration 1 */
#define LTDC_L1LC2R     (0x84)          /* L1 Layer Configuration 2 */
#define LTDC_L1CR       (0x84 + REG_OFS)/* L1 Control */
#define LTDC_L1WHPCR    (0x88 + REG_OFS)/* L1 Window Hor Position Config */
#define LTDC_L1WVPCR    (0x8C + REG_OFS)/* L1 Window Vert Position Config */
#define LTDC_L1CKCR     (0x90 + REG_OFS)/* L1 Color Keying Configuration */
#define LTDC_L1PFCR     (0x94 + REG_OFS)/* L1 Pixel Format Configuration */
#define LTDC_L1CACR     (0x98 + REG_OFS)/* L1 Constant Alpha Config */
#define LTDC_L1DCCR     (0x9C + REG_OFS)/* L1 Default Color Configuration */
#define LTDC_L1BFCR     (0xA0 + REG_OFS)/* L1 Blend Factors Configuration */
#define LTDC_L1FBBCR    (0xA4 + REG_OFS)/* L1 FrameBuffer Bus Control */
#define LTDC_L1AFBCR    (0xA8 + REG_OFS)/* L1 AuxFB Control */
#define LTDC_L1CFBAR    (0xAC + REG_OFS)/* L1 Color FrameBuffer Address */
#define LTDC_L1CFBLR    (0xB0 + REG_OFS)/* L1 Color FrameBuffer Length */
#define LTDC_L1CFBLNR   (0xB4 + REG_OFS)/* L1 Color FrameBuffer Line Nb */
#define LTDC_L1AFBAR    (0xB8 + REG_OFS)/* L1 AuxFB Address */
#define LTDC_L1AFBLR    (0xBC + REG_OFS)/* L1 AuxFB Length */
#define LTDC_L1AFBLNR   (0xC0 + REG_OFS)/* L1 AuxFB Line Number */
#define LTDC_L1CLUTWR   (0xC4 + REG_OFS)/* L1 CLUT Write */
#define LTDC_L1YS1R     (0xE0 + REG_OFS)/* L1 YCbCr Scale 1 */
#define LTDC_L1YS2R     (0xE4 + REG_OFS)/* L1 YCbCr Scale 2 */

/* Bit definitions */
#define SSCR_VSH        GENMASK(10, 0)  /* Vertical Synchronization Height */
#define SSCR_HSW        GENMASK(27, 16) /* Horizontal Synchronization Width */

#define BPCR_AVBP       GENMASK(10, 0)  /* Accumulated Vertical Back Porch */
#define BPCR_AHBP       GENMASK(27, 16) /* Accumulated Horizontal Back Porch */

#define AWCR_AAH        GENMASK(10, 0)  /* Accumulated Active Height */
#define AWCR_AAW        GENMASK(27, 16) /* Accumulated Active Width */

#define TWCR_TOTALH     GENMASK(10, 0)  /* TOTAL Height */
#define TWCR_TOTALW     GENMASK(27, 16) /* TOTAL Width */

#define GCR_LTDCEN      BIT(0)          /* LTDC ENable */
#define GCR_DEN         BIT(16)         /* Dither ENable */
#define GCR_PCPOL       BIT(28)         /* Pixel Clock POLarity-Inverted */
#define GCR_DEPOL       BIT(29)         /* Data Enable POLarity-High */
#define GCR_VSPOL       BIT(30)         /* Vertical Synchro POLarity-High */
#define GCR_HSPOL       BIT(31)         /* Horizontal Synchro POLarity-High */

#define GC1R_WBCH       GENMASK(3, 0)   /* Width of Blue CHannel output */
#define GC1R_WGCH       GENMASK(7, 4)   /* Width of Green Channel output */
#define GC1R_WRCH       GENMASK(11, 8)  /* Width of Red Channel output */
#define GC1R_PBEN       BIT(12)         /* Precise Blending ENable */
#define GC1R_DT         GENMASK(15, 14) /* Dithering Technique */
#define GC1R_GCT        GENMASK(19, 17) /* Gamma Correction Technique */
#define GC1R_SHREN      BIT(21)         /* SHadow Registers ENabled */
#define GC1R_BCP        BIT(22)         /* Background Colour Programmable */
#define GC1R_BBEN       BIT(23)         /* Background Blending ENabled */
#define GC1R_LNIP       BIT(24)         /* Line Number IRQ Position */
#define GC1R_TP         BIT(25)         /* Timing Programmable */
#define GC1R_IPP        BIT(26)         /* IRQ Polarity Programmable */
#define GC1R_SPP        BIT(27)         /* Sync Polarity Programmable */
#define GC1R_DWP        BIT(28)         /* Dither Width Programmable */
#define GC1R_STREN      BIT(29)         /* STatus Registers ENabled */
#define GC1R_BMEN       BIT(31)         /* Blind Mode ENabled */

#define GC2R_EDCA       BIT(0)          /* External Display Control Ability  */
#define GC2R_STSAEN     BIT(1)          /* Slave Timing Sync Ability ENabled */
#define GC2R_DVAEN      BIT(2)          /* Dual-View Ability ENabled */
#define GC2R_DPAEN      BIT(3)          /* Dual-Port Ability ENabled */
#define GC2R_BW         GENMASK(6, 4)   /* Bus Width (log2 of nb of bytes) */
#define GC2R_EDCEN      BIT(7)          /* External Display Control ENabled */

#define SRCR_IMR        BIT(0)          /* IMmediate Reload */
#define SRCR_VBR        BIT(1)          /* Vertical Blanking Reload */

#define BCCR_BCBLACK    0x00            /* Background Color BLACK */
#define BCCR_BCBLUE     GENMASK(7, 0)   /* Background Color BLUE */
#define BCCR_BCGREEN    GENMASK(15, 8)  /* Background Color GREEN */
#define BCCR_BCRED      GENMASK(23, 16) /* Background Color RED */
#define BCCR_BCWHITE    GENMASK(23, 0)  /* Background Color WHITE */

#define IER_LIE         BIT(0)          /* Line Interrupt Enable */
#define IER_FUIE        BIT(1)          /* Fifo Underrun Interrupt Enable */
#define IER_TERRIE      BIT(2)          /* Transfer ERRor Interrupt Enable */
#define IER_RRIE        BIT(3)          /* Register Reload Interrupt enable */

#define CPSR_CYPOS      GENMASK(15, 0)  /* Current Y position */

#define ISR_LIF         BIT(0)          /* Line Interrupt Flag */
#define ISR_FUIF        BIT(1)          /* Fifo Underrun Interrupt Flag */
#define ISR_TERRIF      BIT(2)          /* Transfer ERRor Interrupt Flag */
#define ISR_RRIF        BIT(3)          /* Register Reload Interrupt Flag */

#define LXCR_LEN        BIT(0)          /* Layer ENable */
#define LXCR_COLKEN     BIT(1)          /* Color Keying Enable */
#define LXCR_CLUTEN     BIT(4)          /* Color Look-Up Table ENable */

#define LXWHPCR_WHSTPOS GENMASK(11, 0)  /* Window Horizontal StarT POSition */
#define LXWHPCR_WHSPPOS GENMASK(27, 16) /* Window Horizontal StoP POSition */

#define LXWVPCR_WVSTPOS GENMASK(10, 0)  /* Window Vertical StarT POSition */
#define LXWVPCR_WVSPPOS GENMASK(26, 16) /* Window Vertical StoP POSition */

#define LXPFCR_PF       GENMASK(2, 0)   /* Pixel Format */

#define LXCACR_CONSTA   GENMASK(7, 0)   /* CONSTant Alpha */

#define LXBFCR_BF2      GENMASK(2, 0)   /* Blending Factor 2 */
#define LXBFCR_BF1      GENMASK(10, 8)  /* Blending Factor 1 */

#define LXCFBLR_CFBLL   GENMASK(12, 0)  /* Color Frame Buffer Line Length */
#define LXCFBLR_CFBP    GENMASK(28, 16) /* Color Frame Buffer Pitch in bytes */

#define LXCFBLNR_CFBLN  GENMASK(10, 0)  /* Color Frame Buffer Line Number */

#define CLUT_SIZE       256

#define CONSTA_MAX      0xFF            /* CONSTant Alpha MAX= 1.0 */
#define BF1_PAXCA       0x600           /* Pixel Alpha x Constant Alpha */
#define BF1_CA          0x400           /* Constant Alpha */
#define BF2_1PAXCA      0x007           /* 1 - (Pixel Alpha x Constant Alpha) */
#define BF2_1CA         0x005           /* 1 - Constant Alpha */

#define NB_PF           8               /* Max nb of HW pixel format */

enum ltdc_pix_fmt {
        PF_NONE,
        /* RGB formats */
        PF_ARGB8888,            /* ARGB [32 bits] */
        PF_RGBA8888,            /* RGBA [32 bits] */
        PF_RGB888,              /* RGB [24 bits] */
        PF_RGB565,              /* RGB [16 bits] */
        PF_ARGB1555,            /* ARGB A:1 bit RGB:15 bits [16 bits] */
        PF_ARGB4444,            /* ARGB A:4 bits R/G/B: 4 bits each [16 bits] */
        /* Indexed formats */
        PF_L8,                  /* Indexed 8 bits [8 bits] */
        PF_AL44,                /* Alpha:4 bits + indexed 4 bits [8 bits] */
        PF_AL88                 /* Alpha:8 bits + indexed 8 bits [16 bits] */
};

/* The index gives the encoding of the pixel format for an HW version */
static const enum ltdc_pix_fmt ltdc_pix_fmt_a0[NB_PF] = {
        PF_ARGB8888,            /* 0x00 */
        PF_RGB888,              /* 0x01 */
        PF_RGB565,              /* 0x02 */
        PF_ARGB1555,            /* 0x03 */
        PF_ARGB4444,            /* 0x04 */
        PF_L8,                  /* 0x05 */
        PF_AL44,                /* 0x06 */
        PF_AL88                 /* 0x07 */
};

static const enum ltdc_pix_fmt ltdc_pix_fmt_a1[NB_PF] = {
        PF_ARGB8888,            /* 0x00 */
        PF_RGB888,              /* 0x01 */
        PF_RGB565,              /* 0x02 */
        PF_RGBA8888,            /* 0x03 */
        PF_AL44,                /* 0x04 */
        PF_L8,                  /* 0x05 */
        PF_ARGB1555,            /* 0x06 */
        PF_ARGB4444             /* 0x07 */
};

static const u64 ltdc_format_modifiers[] = {
        DRM_FORMAT_MOD_LINEAR,
        DRM_FORMAT_MOD_INVALID
};

static inline u32 reg_read(void __iomem *base, u32 reg)
{
        return readl_relaxed(base + reg);
}

static inline void reg_write(void __iomem *base, u32 reg, u32 val)
{
        writel_relaxed(val, base + reg);
}

static inline void reg_set(void __iomem *base, u32 reg, u32 mask)
{
        reg_write(base, reg, reg_read(base, reg) | mask);
}

static inline void reg_clear(void __iomem *base, u32 reg, u32 mask)
{
        reg_write(base, reg, reg_read(base, reg) & ~mask);
}

static inline void reg_update_bits(void __iomem *base, u32 reg, u32 mask,
                                   u32 val)
{
        reg_write(base, reg, (reg_read(base, reg) & ~mask) | val);
}

static inline struct ltdc_device *crtc_to_ltdc(struct drm_crtc *crtc)
{
        return (struct ltdc_device *)crtc->dev->dev_private;
}

static inline struct ltdc_device *plane_to_ltdc(struct drm_plane *plane)
{
        return (struct ltdc_device *)plane->dev->dev_private;
}

static inline struct ltdc_device *encoder_to_ltdc(struct drm_encoder *enc)
{
        return (struct ltdc_device *)enc->dev->dev_private;
}

static inline enum ltdc_pix_fmt to_ltdc_pixelformat(u32 drm_fmt)
{
        enum ltdc_pix_fmt pf;

        switch (drm_fmt) {
        case DRM_FORMAT_ARGB8888:
        case DRM_FORMAT_XRGB8888:
                pf = PF_ARGB8888;
                break;
        case DRM_FORMAT_RGBA8888:
        case DRM_FORMAT_RGBX8888:
                pf = PF_RGBA8888;
                break;
        case DRM_FORMAT_RGB888:
                pf = PF_RGB888;
                break;
        case DRM_FORMAT_RGB565:
                pf = PF_RGB565;
                break;
        case DRM_FORMAT_ARGB1555:
        case DRM_FORMAT_XRGB1555:
                pf = PF_ARGB1555;
                break;
        case DRM_FORMAT_ARGB4444:
        case DRM_FORMAT_XRGB4444:
                pf = PF_ARGB4444;
                break;
        case DRM_FORMAT_C8:
                pf = PF_L8;
                break;
        default:
                pf = PF_NONE;
                break;
                /* Note: There are no DRM_FORMAT for AL44 and AL88 */
        }

        return pf;
}

static inline u32 to_drm_pixelformat(enum ltdc_pix_fmt pf)
{
        switch (pf) {
        case PF_ARGB8888:
                return DRM_FORMAT_ARGB8888;
        case PF_RGBA8888:
                return DRM_FORMAT_RGBA8888;
        case PF_RGB888:
                return DRM_FORMAT_RGB888;
        case PF_RGB565:
                return DRM_FORMAT_RGB565;
        case PF_ARGB1555:
                return DRM_FORMAT_ARGB1555;
        case PF_ARGB4444:
                return DRM_FORMAT_ARGB4444;
        case PF_L8:
                return DRM_FORMAT_C8;
        case PF_AL44:           /* No DRM support */
        case PF_AL88:           /* No DRM support */
        case PF_NONE:
        default:
                return 0;
        }
}

static inline u32 get_pixelformat_without_alpha(u32 drm)
{
        switch (drm) {
        case DRM_FORMAT_ARGB4444:
                return DRM_FORMAT_XRGB4444;
        case DRM_FORMAT_RGBA4444:
                return DRM_FORMAT_RGBX4444;
        case DRM_FORMAT_ARGB1555:
                return DRM_FORMAT_XRGB1555;
        case DRM_FORMAT_RGBA5551:
                return DRM_FORMAT_RGBX5551;
        case DRM_FORMAT_ARGB8888:
                return DRM_FORMAT_XRGB8888;
        case DRM_FORMAT_RGBA8888:
                return DRM_FORMAT_RGBX8888;
        default:
                return 0;
        }
}

static irqreturn_t ltdc_irq_thread(int irq, void *arg)
{
        struct drm_device *ddev = arg;
        struct ltdc_device *ldev = ddev->dev_private;
        struct drm_crtc *crtc = drm_crtc_from_index(ddev, 0);

        /* Line IRQ : trigger the vblank event */
        if (ldev->irq_status & ISR_LIF)
                drm_crtc_handle_vblank(crtc);

        /* Save FIFO Underrun & Transfer Error status */
        mutex_lock(&ldev->err_lock);
        if (ldev->irq_status & ISR_FUIF)
                ldev->error_status |= ISR_FUIF;
        if (ldev->irq_status & ISR_TERRIF)
                ldev->error_status |= ISR_TERRIF;
        mutex_unlock(&ldev->err_lock);

        return IRQ_HANDLED;
}

static irqreturn_t ltdc_irq(int irq, void *arg)
{
        struct drm_device *ddev = arg;
        struct ltdc_device *ldev = ddev->dev_private;

        /* Read & Clear the interrupt status */
        ldev->irq_status = reg_read(ldev->regs, LTDC_ISR);
        reg_write(ldev->regs, LTDC_ICR, ldev->irq_status);

        return IRQ_WAKE_THREAD;
}

/*
 * DRM_CRTC
 */

static void ltdc_crtc_update_clut(struct drm_crtc *crtc)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);
        struct drm_color_lut *lut;
        u32 val;
        int i;

        if (!crtc->state->color_mgmt_changed || !crtc->state->gamma_lut)
                return;

        lut = (struct drm_color_lut *)crtc->state->gamma_lut->data;

        for (i = 0; i < CLUT_SIZE; i++, lut++) {
                val = ((lut->red << 8) & 0xff0000) | (lut->green & 0xff00) |
                        (lut->blue >> 8) | (i << 24);
                reg_write(ldev->regs, LTDC_L1CLUTWR, val);
        }
}

static void ltdc_crtc_atomic_enable(struct drm_crtc *crtc,
                                    struct drm_atomic_state *state)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);
        struct drm_device *ddev = crtc->dev;

        DRM_DEBUG_DRIVER("\n");

        pm_runtime_get_sync(ddev->dev);

        /* Sets the background color value */
        reg_write(ldev->regs, LTDC_BCCR, BCCR_BCBLACK);

        /* Enable IRQ */
        reg_set(ldev->regs, LTDC_IER, IER_RRIE | IER_FUIE | IER_TERRIE);

        /* Commit shadow registers = update planes at next vblank */
        reg_set(ldev->regs, LTDC_SRCR, SRCR_VBR);

        drm_crtc_vblank_on(crtc);
}

static void ltdc_crtc_atomic_disable(struct drm_crtc *crtc,
                                     struct drm_atomic_state *state)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);
        struct drm_device *ddev = crtc->dev;

        DRM_DEBUG_DRIVER("\n");

        drm_crtc_vblank_off(crtc);

        /* disable IRQ */
        reg_clear(ldev->regs, LTDC_IER, IER_RRIE | IER_FUIE | IER_TERRIE);

        /* immediately commit disable of layers before switching off LTDC */
        reg_set(ldev->regs, LTDC_SRCR, SRCR_IMR);

        pm_runtime_put_sync(ddev->dev);
}

#define CLK_TOLERANCE_HZ 50

static enum drm_mode_status
ltdc_crtc_mode_valid(struct drm_crtc *crtc,
                     const struct drm_display_mode *mode)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);
        int target = mode->clock * 1000;
        int target_min = target - CLK_TOLERANCE_HZ;
        int target_max = target + CLK_TOLERANCE_HZ;
        int result;

        result = clk_round_rate(ldev->pixel_clk, target);

        DRM_DEBUG_DRIVER("clk rate target %d, available %d\n", target, result);

        /* Filter modes according to the max frequency supported by the pads */
        if (result > ldev->caps.pad_max_freq_hz)
                return MODE_CLOCK_HIGH;

        /*
         * Accept all "preferred" modes:
         * - this is important for panels because panel clock tolerances are
         *   bigger than hdmi ones and there is no reason to not accept them
         *   (the fps may vary a little but it is not a problem).
         * - the hdmi preferred mode will be accepted too, but userland will
         *   be able to use others hdmi "valid" modes if necessary.
         */
        if (mode->type & DRM_MODE_TYPE_PREFERRED)
                return MODE_OK;

        /*
         * Filter modes according to the clock value, particularly useful for
         * hdmi modes that require precise pixel clocks.
         */
        if (result < target_min || result > target_max)
                return MODE_CLOCK_RANGE;

        return MODE_OK;
}

static bool ltdc_crtc_mode_fixup(struct drm_crtc *crtc,
                                 const struct drm_display_mode *mode,
                                 struct drm_display_mode *adjusted_mode)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);
        int rate = mode->clock * 1000;

        if (clk_set_rate(ldev->pixel_clk, rate) < 0) {
                DRM_ERROR("Cannot set rate (%dHz) for pixel clk\n", rate);
                return false;
        }

        adjusted_mode->clock = clk_get_rate(ldev->pixel_clk) / 1000;

        DRM_DEBUG_DRIVER("requested clock %dkHz, adjusted clock %dkHz\n",
                         mode->clock, adjusted_mode->clock);

        return true;
}

static void ltdc_crtc_mode_set_nofb(struct drm_crtc *crtc)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);
        struct drm_device *ddev = crtc->dev;
        struct drm_connector_list_iter iter;
        struct drm_connector *connector = NULL;
        struct drm_encoder *encoder = NULL;
        struct drm_bridge *bridge = NULL;
        struct drm_display_mode *mode = &crtc->state->adjusted_mode;
        u32 hsync, vsync, accum_hbp, accum_vbp, accum_act_w, accum_act_h;
        u32 total_width, total_height;
        u32 bus_flags = 0;
        u32 val;
        int ret;

        /* get encoder from crtc */
        drm_for_each_encoder(encoder, ddev)
                if (encoder->crtc == crtc)
                        break;

        if (encoder) {
                /* get bridge from encoder */
                list_for_each_entry(bridge, &encoder->bridge_chain, chain_node)
                        if (bridge->encoder == encoder)
                                break;

                /* Get the connector from encoder */
                drm_connector_list_iter_begin(ddev, &iter);
                drm_for_each_connector_iter(connector, &iter)
                        if (connector->encoder == encoder)
                                break;
                drm_connector_list_iter_end(&iter);
        }

        if (bridge && bridge->timings)
                bus_flags = bridge->timings->input_bus_flags;
        else if (connector)
                bus_flags = connector->display_info.bus_flags;

        if (!pm_runtime_active(ddev->dev)) {
                ret = pm_runtime_get_sync(ddev->dev);
                if (ret) {
                        DRM_ERROR("Failed to set mode, cannot get sync\n");
                        return;
                }
        }

        DRM_DEBUG_DRIVER("CRTC:%d mode:%s\n", crtc->base.id, mode->name);
        DRM_DEBUG_DRIVER("Video mode: %dx%d", mode->hdisplay, mode->vdisplay);
        DRM_DEBUG_DRIVER(" hfp %d hbp %d hsl %d vfp %d vbp %d vsl %d\n",
                         mode->hsync_start - mode->hdisplay,
                         mode->htotal - mode->hsync_end,
                         mode->hsync_end - mode->hsync_start,
                         mode->vsync_start - mode->vdisplay,
                         mode->vtotal - mode->vsync_end,
                         mode->vsync_end - mode->vsync_start);

        /* Convert video timings to ltdc timings */
        hsync = mode->hsync_end - mode->hsync_start - 1;
        vsync = mode->vsync_end - mode->vsync_start - 1;
        accum_hbp = mode->htotal - mode->hsync_start - 1;
        accum_vbp = mode->vtotal - mode->vsync_start - 1;
        accum_act_w = accum_hbp + mode->hdisplay;
        accum_act_h = accum_vbp + mode->vdisplay;
        total_width = mode->htotal - 1;
        total_height = mode->vtotal - 1;

        /* Configures the HS, VS, DE and PC polarities. Default Active Low */
        val = 0;

        if (mode->flags & DRM_MODE_FLAG_PHSYNC)
                val |= GCR_HSPOL;

        if (mode->flags & DRM_MODE_FLAG_PVSYNC)
                val |= GCR_VSPOL;

        if (bus_flags & DRM_BUS_FLAG_DE_LOW)
                val |= GCR_DEPOL;

        if (bus_flags & DRM_BUS_FLAG_PIXDATA_DRIVE_NEGEDGE)
                val |= GCR_PCPOL;

        reg_update_bits(ldev->regs, LTDC_GCR,
                        GCR_HSPOL | GCR_VSPOL | GCR_DEPOL | GCR_PCPOL, val);

        /* Set Synchronization size */
        val = (hsync << 16) | vsync;
        reg_update_bits(ldev->regs, LTDC_SSCR, SSCR_VSH | SSCR_HSW, val);

        /* Set Accumulated Back porch */
        val = (accum_hbp << 16) | accum_vbp;
        reg_update_bits(ldev->regs, LTDC_BPCR, BPCR_AVBP | BPCR_AHBP, val);

        /* Set Accumulated Active Width */
        val = (accum_act_w << 16) | accum_act_h;
        reg_update_bits(ldev->regs, LTDC_AWCR, AWCR_AAW | AWCR_AAH, val);

        /* Set total width & height */
        val = (total_width << 16) | total_height;
        reg_update_bits(ldev->regs, LTDC_TWCR, TWCR_TOTALH | TWCR_TOTALW, val);

        reg_write(ldev->regs, LTDC_LIPCR, (accum_act_h + 1));
}

static void ltdc_crtc_atomic_flush(struct drm_crtc *crtc,
                                   struct drm_atomic_state *state)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);
        struct drm_device *ddev = crtc->dev;
        struct drm_pending_vblank_event *event = crtc->state->event;

        DRM_DEBUG_ATOMIC("\n");

        ltdc_crtc_update_clut(crtc);

        /* Commit shadow registers = update planes at next vblank */
        reg_set(ldev->regs, LTDC_SRCR, SRCR_VBR);

        if (event) {
                crtc->state->event = NULL;

                spin_lock_irq(&ddev->event_lock);
                if (drm_crtc_vblank_get(crtc) == 0)
                        drm_crtc_arm_vblank_event(crtc, event);
                else
                        drm_crtc_send_vblank_event(crtc, event);
                spin_unlock_irq(&ddev->event_lock);
        }
}

static bool ltdc_crtc_get_scanout_position(struct drm_crtc *crtc,
                                           bool in_vblank_irq,
                                           int *vpos, int *hpos,
                                           ktime_t *stime, ktime_t *etime,
                                           const struct drm_display_mode *mode)
{
        struct drm_device *ddev = crtc->dev;
        struct ltdc_device *ldev = ddev->dev_private;
        int line, vactive_start, vactive_end, vtotal;

        if (stime)
                *stime = ktime_get();

        /* The active area starts after vsync + front porch and ends
         * at vsync + front porc + display size.
         * The total height also include back porch.
         * We have 3 possible cases to handle:
         * - line < vactive_start: vpos = line - vactive_start and will be
         * negative
         * - vactive_start < line < vactive_end: vpos = line - vactive_start
         * and will be positive
         * - line > vactive_end: vpos = line - vtotal - vactive_start
         * and will negative
         *
         * Computation for the two first cases are identical so we can
         * simplify the code and only test if line > vactive_end
         */
        if (pm_runtime_active(ddev->dev)) {
                line = reg_read(ldev->regs, LTDC_CPSR) & CPSR_CYPOS;
                vactive_start = reg_read(ldev->regs, LTDC_BPCR) & BPCR_AVBP;
                vactive_end = reg_read(ldev->regs, LTDC_AWCR) & AWCR_AAH;
                vtotal = reg_read(ldev->regs, LTDC_TWCR) & TWCR_TOTALH;

                if (line > vactive_end)
                        *vpos = line - vtotal - vactive_start;
                else
                        *vpos = line - vactive_start;
        } else {
                *vpos = 0;
        }

        *hpos = 0;

        if (etime)
                *etime = ktime_get();

        return true;
}

static const struct drm_crtc_helper_funcs ltdc_crtc_helper_funcs = {
        .mode_valid = ltdc_crtc_mode_valid,
        .mode_fixup = ltdc_crtc_mode_fixup,
        .mode_set_nofb = ltdc_crtc_mode_set_nofb,
        .atomic_flush = ltdc_crtc_atomic_flush,
        .atomic_enable = ltdc_crtc_atomic_enable,
        .atomic_disable = ltdc_crtc_atomic_disable,
        .get_scanout_position = ltdc_crtc_get_scanout_position,
};

static int ltdc_crtc_enable_vblank(struct drm_crtc *crtc)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);
        struct drm_crtc_state *state = crtc->state;

        DRM_DEBUG_DRIVER("\n");

        if (state->enable)
                reg_set(ldev->regs, LTDC_IER, IER_LIE);
        else
                return -EPERM;

        return 0;
}

static void ltdc_crtc_disable_vblank(struct drm_crtc *crtc)
{
        struct ltdc_device *ldev = crtc_to_ltdc(crtc);

        DRM_DEBUG_DRIVER("\n");
        reg_clear(ldev->regs, LTDC_IER, IER_LIE);
}

static const struct drm_crtc_funcs ltdc_crtc_funcs = {
        .destroy = drm_crtc_cleanup,
        .set_config = drm_atomic_helper_set_config,
        .page_flip = drm_atomic_helper_page_flip,
        .reset = drm_atomic_helper_crtc_reset,
        .atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
        .enable_vblank = ltdc_crtc_enable_vblank,
        .disable_vblank = ltdc_crtc_disable_vblank,
        .get_vblank_timestamp = drm_crtc_vblank_helper_get_vblank_timestamp,
};

/*
 * DRM_PLANE
 */

static int ltdc_plane_atomic_check(struct drm_plane *plane,
                                   struct drm_atomic_state *state)
{
        struct drm_plane_state *new_plane_state = drm_atomic_get_new_plane_state(state,
                                                                                 plane);
        struct drm_framebuffer *fb = new_plane_state->fb;
        u32 src_w, src_h;

        DRM_DEBUG_DRIVER("\n");

        if (!fb)
                return 0;

        /* convert src_ from 16:16 format */
        src_w = new_plane_state->src_w >> 16;
        src_h = new_plane_state->src_h >> 16;

        /* Reject scaling */
        if (src_w != new_plane_state->crtc_w || src_h != new_plane_state->crtc_h) {
                DRM_ERROR("Scaling is not supported");
                return -EINVAL;
        }

        return 0;
}

static void ltdc_plane_atomic_update(struct drm_plane *plane,
                                     struct drm_atomic_state *state)
{
        struct ltdc_device *ldev = plane_to_ltdc(plane);
        struct drm_plane_state *newstate = drm_atomic_get_new_plane_state(state,
                                                                          plane);
        struct drm_framebuffer *fb = newstate->fb;
        u32 lofs = plane->index * LAY_OFS;
        u32 x0 = newstate->crtc_x;
        u32 x1 = newstate->crtc_x + newstate->crtc_w - 1;
        u32 y0 = newstate->crtc_y;
        u32 y1 = newstate->crtc_y + newstate->crtc_h - 1;
        u32 src_x, src_y, src_w, src_h;
        u32 val, pitch_in_bytes, line_length, paddr, ahbp, avbp, bpcr;
        enum ltdc_pix_fmt pf;

        if (!newstate->crtc || !fb) {
                DRM_DEBUG_DRIVER("fb or crtc NULL");
                return;
        }

        /* convert src_ from 16:16 format */
        src_x = newstate->src_x >> 16;
        src_y = newstate->src_y >> 16;
        src_w = newstate->src_w >> 16;
        src_h = newstate->src_h >> 16;

        DRM_DEBUG_DRIVER("plane:%d fb:%d (%dx%d)@(%d,%d) -> (%dx%d)@(%d,%d)\n",
                         plane->base.id, fb->base.id,
                         src_w, src_h, src_x, src_y,
                         newstate->crtc_w, newstate->crtc_h,
                         newstate->crtc_x, newstate->crtc_y);

        bpcr = reg_read(ldev->regs, LTDC_BPCR);
        ahbp = (bpcr & BPCR_AHBP) >> 16;
        avbp = bpcr & BPCR_AVBP;

        /* Configures the horizontal start and stop position */
        val = ((x1 + 1 + ahbp) << 16) + (x0 + 1 + ahbp);
        reg_update_bits(ldev->regs, LTDC_L1WHPCR + lofs,
                        LXWHPCR_WHSTPOS | LXWHPCR_WHSPPOS, val);

        /* Configures the vertical start and stop position */
        val = ((y1 + 1 + avbp) << 16) + (y0 + 1 + avbp);
        reg_update_bits(ldev->regs, LTDC_L1WVPCR + lofs,
                        LXWVPCR_WVSTPOS | LXWVPCR_WVSPPOS, val);

        /* Specifies the pixel format */
        pf = to_ltdc_pixelformat(fb->format->format);
        for (val = 0; val < NB_PF; val++)
                if (ldev->caps.pix_fmt_hw[val] == pf)
                        break;

        if (val == NB_PF) {
                DRM_ERROR("Pixel format %.4s not supported\n",
                          (char *)&fb->format->format);
                val = 0;        /* set by default ARGB 32 bits */
        }
        reg_update_bits(ldev->regs, LTDC_L1PFCR + lofs, LXPFCR_PF, val);

        /* Configures the color frame buffer pitch in bytes & line length */
        pitch_in_bytes = fb->pitches[0];
        line_length = fb->format->cpp[0] *
                      (x1 - x0 + 1) + (ldev->caps.bus_width >> 3) - 1;
        val = ((pitch_in_bytes << 16) | line_length);
        reg_update_bits(ldev->regs, LTDC_L1CFBLR + lofs,
                        LXCFBLR_CFBLL | LXCFBLR_CFBP, val);

        /* Specifies the constant alpha value */
        val = CONSTA_MAX;
        reg_update_bits(ldev->regs, LTDC_L1CACR + lofs, LXCACR_CONSTA, val);

        /* Specifies the blending factors */
        val = BF1_PAXCA | BF2_1PAXCA;
        if (!fb->format->has_alpha)
                val = BF1_CA | BF2_1CA;

        /* Manage hw-specific capabilities */
        if (ldev->caps.non_alpha_only_l1 &&
            plane->type != DRM_PLANE_TYPE_PRIMARY)
                val = BF1_PAXCA | BF2_1PAXCA;

        reg_update_bits(ldev->regs, LTDC_L1BFCR + lofs,
                        LXBFCR_BF2 | LXBFCR_BF1, val);

        /* Configures the frame buffer line number */
        val = y1 - y0 + 1;
        reg_update_bits(ldev->regs, LTDC_L1CFBLNR + lofs, LXCFBLNR_CFBLN, val);

        /* Sets the FB address */
        paddr = (u32)drm_fb_cma_get_gem_addr(fb, newstate, 0);

        DRM_DEBUG_DRIVER("fb: phys 0x%08x", paddr);
        reg_write(ldev->regs, LTDC_L1CFBAR + lofs, paddr);

        /* Enable layer and CLUT if needed */
        val = fb->format->format == DRM_FORMAT_C8 ? LXCR_CLUTEN : 0;
        val |= LXCR_LEN;
        reg_update_bits(ldev->regs, LTDC_L1CR + lofs,
                        LXCR_LEN | LXCR_CLUTEN, val);

        ldev->plane_fpsi[plane->index].counter++;

        mutex_lock(&ldev->err_lock);
        if (ldev->error_status & ISR_FUIF) {
                DRM_WARN("ltdc fifo underrun: please verify display mode\n");
                ldev->error_status &= ~ISR_FUIF;
        }
        if (ldev->error_status & ISR_TERRIF) {
                DRM_WARN("ltdc transfer error\n");
                ldev->error_status &= ~ISR_TERRIF;
        }
        mutex_unlock(&ldev->err_lock);
}

static void ltdc_plane_atomic_disable(struct drm_plane *plane,
                                      struct drm_atomic_state *state)
{
        struct drm_plane_state *oldstate = drm_atomic_get_old_plane_state(state,
                                                                          plane);
        struct ltdc_device *ldev = plane_to_ltdc(plane);
        u32 lofs = plane->index * LAY_OFS;

        /* disable layer */
        reg_clear(ldev->regs, LTDC_L1CR + lofs, LXCR_LEN);

        DRM_DEBUG_DRIVER("CRTC:%d plane:%d\n",
                         oldstate->crtc->base.id, plane->base.id);
}

static void ltdc_plane_atomic_print_state(struct drm_printer *p,
                                          const struct drm_plane_state *state)
{
        struct drm_plane *plane = state->plane;
        struct ltdc_device *ldev = plane_to_ltdc(plane);
        struct fps_info *fpsi = &ldev->plane_fpsi[plane->index];
        int ms_since_last;
        ktime_t now;

        now = ktime_get();
        ms_since_last = ktime_to_ms(ktime_sub(now, fpsi->last_timestamp));

        drm_printf(p, "\tuser_updates=%dfps\n",
                   DIV_ROUND_CLOSEST(fpsi->counter * 1000, ms_since_last));

        fpsi->last_timestamp = now;
        fpsi->counter = 0;
}

static bool ltdc_plane_format_mod_supported(struct drm_plane *plane,
                                            u32 format,
                                            u64 modifier)
{
        if (modifier == DRM_FORMAT_MOD_LINEAR)
                return true;

        return false;
}

static const struct drm_plane_funcs ltdc_plane_funcs = {
        .update_plane = drm_atomic_helper_update_plane,
        .disable_plane = drm_atomic_helper_disable_plane,
        .destroy = drm_plane_cleanup,
        .reset = drm_atomic_helper_plane_reset,
        .atomic_duplicate_state = drm_atomic_helper_plane_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_plane_destroy_state,
        .atomic_print_state = ltdc_plane_atomic_print_state,
        .format_mod_supported = ltdc_plane_format_mod_supported,
};

static const struct drm_plane_helper_funcs ltdc_plane_helper_funcs = {
        .atomic_check = ltdc_plane_atomic_check,
        .atomic_update = ltdc_plane_atomic_update,
        .atomic_disable = ltdc_plane_atomic_disable,
};

static struct drm_plane *ltdc_plane_create(struct drm_device *ddev,
                                           enum drm_plane_type type)
{
        unsigned long possible_crtcs = CRTC_MASK;
        struct ltdc_device *ldev = ddev->dev_private;
        struct device *dev = ddev->dev;
        struct drm_plane *plane;
        unsigned int i, nb_fmt = 0;
        u32 formats[NB_PF * 2];
        u32 drm_fmt, drm_fmt_no_alpha;
        const u64 *modifiers = ltdc_format_modifiers;
        int ret;

        /* Get supported pixel formats */
        for (i = 0; i < NB_PF; i++) {
                drm_fmt = to_drm_pixelformat(ldev->caps.pix_fmt_hw[i]);
                if (!drm_fmt)
                        continue;
                formats[nb_fmt++] = drm_fmt;

                /* Add the no-alpha related format if any & supported */
                drm_fmt_no_alpha = get_pixelformat_without_alpha(drm_fmt);
                if (!drm_fmt_no_alpha)
                        continue;

                /* Manage hw-specific capabilities */
                if (ldev->caps.non_alpha_only_l1 &&
                    type != DRM_PLANE_TYPE_PRIMARY)
                        continue;

                formats[nb_fmt++] = drm_fmt_no_alpha;
        }

        plane = devm_kzalloc(dev, sizeof(*plane), GFP_KERNEL);
        if (!plane)
                return NULL;

        ret = drm_universal_plane_init(ddev, plane, possible_crtcs,
                                       &ltdc_plane_funcs, formats, nb_fmt,
                                       modifiers, type, NULL);
        if (ret < 0)
                return NULL;

        drm_plane_helper_add(plane, &ltdc_plane_helper_funcs);

        DRM_DEBUG_DRIVER("plane:%d created\n", plane->base.id);

        return plane;
}

static void ltdc_plane_destroy_all(struct drm_device *ddev)
{
        struct drm_plane *plane, *plane_temp;

        list_for_each_entry_safe(plane, plane_temp,
                                 &ddev->mode_config.plane_list, head)
                drm_plane_cleanup(plane);
}

static int ltdc_crtc_init(struct drm_device *ddev, struct drm_crtc *crtc)
{
        struct ltdc_device *ldev = ddev->dev_private;
        struct drm_plane *primary, *overlay;
        unsigned int i;
        int ret;

        primary = ltdc_plane_create(ddev, DRM_PLANE_TYPE_PRIMARY);
        if (!primary) {
                DRM_ERROR("Can not create primary plane\n");
                return -EINVAL;
        }

        ret = drm_crtc_init_with_planes(ddev, crtc, primary, NULL,
                                        &ltdc_crtc_funcs, NULL);
        if (ret) {
                DRM_ERROR("Can not initialize CRTC\n");
                goto cleanup;
        }

        drm_crtc_helper_add(crtc, &ltdc_crtc_helper_funcs);

        drm_mode_crtc_set_gamma_size(crtc, CLUT_SIZE);
        drm_crtc_enable_color_mgmt(crtc, 0, false, CLUT_SIZE);

        DRM_DEBUG_DRIVER("CRTC:%d created\n", crtc->base.id);

        /* Add planes. Note : the first layer is used by primary plane */
        for (i = 1; i < ldev->caps.nb_layers; i++) {
                overlay = ltdc_plane_create(ddev, DRM_PLANE_TYPE_OVERLAY);
                if (!overlay) {
                        ret = -ENOMEM;
                        DRM_ERROR("Can not create overlay plane %d\n", i);
                        goto cleanup;
                }
        }

        return 0;

cleanup:
        ltdc_plane_destroy_all(ddev);
        return ret;
}

static void ltdc_encoder_disable(struct drm_encoder *encoder)
{
        struct drm_device *ddev = encoder->dev;
        struct ltdc_device *ldev = ddev->dev_private;

        DRM_DEBUG_DRIVER("\n");

        /* Disable LTDC */
        reg_clear(ldev->regs, LTDC_GCR, GCR_LTDCEN);

        /* Set to sleep state the pinctrl whatever type of encoder */
        pinctrl_pm_select_sleep_state(ddev->dev);
}

static void ltdc_encoder_enable(struct drm_encoder *encoder)
{
        struct drm_device *ddev = encoder->dev;
        struct ltdc_device *ldev = ddev->dev_private;

        DRM_DEBUG_DRIVER("\n");

        /* Enable LTDC */
        reg_set(ldev->regs, LTDC_GCR, GCR_LTDCEN);
}

static void ltdc_encoder_mode_set(struct drm_encoder *encoder,
                                  struct drm_display_mode *mode,
                                  struct drm_display_mode *adjusted_mode)
{
        struct drm_device *ddev = encoder->dev;

        DRM_DEBUG_DRIVER("\n");

        /*
         * Set to default state the pinctrl only with DPI type.
         * Others types like DSI, don't need pinctrl due to
         * internal bridge (the signals do not come out of the chipset).
         */
        if (encoder->encoder_type == DRM_MODE_ENCODER_DPI)
                pinctrl_pm_select_default_state(ddev->dev);
}

static const struct drm_encoder_helper_funcs ltdc_encoder_helper_funcs = {
        .disable = ltdc_encoder_disable,
        .enable = ltdc_encoder_enable,
        .mode_set = ltdc_encoder_mode_set,
};

static int ltdc_encoder_init(struct drm_device *ddev, struct drm_bridge *bridge)
{
        struct drm_encoder *encoder;
        int ret;

        encoder = devm_kzalloc(ddev->dev, sizeof(*encoder), GFP_KERNEL);
        if (!encoder)
                return -ENOMEM;

        encoder->possible_crtcs = CRTC_MASK;
        encoder->possible_clones = 0;   /* No cloning support */

        drm_simple_encoder_init(ddev, encoder, DRM_MODE_ENCODER_DPI);

        drm_encoder_helper_add(encoder, &ltdc_encoder_helper_funcs);

        ret = drm_bridge_attach(encoder, bridge, NULL, 0);
        if (ret) {
                if (ret != -EPROBE_DEFER)
                        drm_encoder_cleanup(encoder);
                return ret;
        }

        DRM_DEBUG_DRIVER("Bridge encoder:%d created\n", encoder->base.id);

        return 0;
}

static int ltdc_get_caps(struct drm_device *ddev)
{
        struct ltdc_device *ldev = ddev->dev_private;
        u32 bus_width_log2, lcr, gc2r;

        /*
         * at least 1 layer must be managed & the number of layers
         * must not exceed LTDC_MAX_LAYER
         */
        lcr = reg_read(ldev->regs, LTDC_LCR);

        ldev->caps.nb_layers = clamp((int)lcr, 1, LTDC_MAX_LAYER);

        /* set data bus width */
        gc2r = reg_read(ldev->regs, LTDC_GC2R);
        bus_width_log2 = (gc2r & GC2R_BW) >> 4;
        ldev->caps.bus_width = 8 << bus_width_log2;
        ldev->caps.hw_version = reg_read(ldev->regs, LTDC_IDR);

        switch (ldev->caps.hw_version) {
        case HWVER_10200:
        case HWVER_10300:
                ldev->caps.reg_ofs = REG_OFS_NONE;
                ldev->caps.pix_fmt_hw = ltdc_pix_fmt_a0;
                /*
                 * Hw older versions support non-alpha color formats derived
                 * from native alpha color formats only on the primary layer.
                 * For instance, RG16 native format without alpha works fine
                 * on 2nd layer but XR24 (derived color format from AR24)
                 * does not work on 2nd layer.
                 */
                ldev->caps.non_alpha_only_l1 = true;
                ldev->caps.pad_max_freq_hz = 90000000;
                if (ldev->caps.hw_version == HWVER_10200)
                        ldev->caps.pad_max_freq_hz = 65000000;
                ldev->caps.nb_irq = 2;
                break;
        case HWVER_20101:
                ldev->caps.reg_ofs = REG_OFS_4;
                ldev->caps.pix_fmt_hw = ltdc_pix_fmt_a1;
                ldev->caps.non_alpha_only_l1 = false;
                ldev->caps.pad_max_freq_hz = 150000000;
                ldev->caps.nb_irq = 4;
                break;
        default:
                return -ENODEV;
        }

        return 0;
}

void ltdc_suspend(struct drm_device *ddev)
{
        struct ltdc_device *ldev = ddev->dev_private;

        DRM_DEBUG_DRIVER("\n");
        clk_disable_unprepare(ldev->pixel_clk);
}

int ltdc_resume(struct drm_device *ddev)
{
        struct ltdc_device *ldev = ddev->dev_private;
        int ret;

        DRM_DEBUG_DRIVER("\n");

        ret = clk_prepare_enable(ldev->pixel_clk);
        if (ret) {
                DRM_ERROR("failed to enable pixel clock (%d)\n", ret);
                return ret;
        }

        return 0;
}

int ltdc_load(struct drm_device *ddev)
{
        struct platform_device *pdev = to_platform_device(ddev->dev);
        struct ltdc_device *ldev = ddev->dev_private;
        struct device *dev = ddev->dev;
        struct device_node *np = dev->of_node;
        struct drm_bridge *bridge;
        struct drm_panel *panel;
        struct drm_crtc *crtc;
        struct reset_control *rstc;
        struct resource *res;
        int irq, i, nb_endpoints;
        int ret = -ENODEV;

        DRM_DEBUG_DRIVER("\n");

        /* Get number of endpoints */
        nb_endpoints = of_graph_get_endpoint_count(np);
        if (!nb_endpoints)
                return -ENODEV;

        ldev->pixel_clk = devm_clk_get(dev, "lcd");
        if (IS_ERR(ldev->pixel_clk)) {
                if (PTR_ERR(ldev->pixel_clk) != -EPROBE_DEFER)
                        DRM_ERROR("Unable to get lcd clock\n");
                return PTR_ERR(ldev->pixel_clk);
        }

        if (clk_prepare_enable(ldev->pixel_clk)) {
                DRM_ERROR("Unable to prepare pixel clock\n");
                return -ENODEV;
        }

        /* Get endpoints if any */
        for (i = 0; i < nb_endpoints; i++) {
                ret = drm_of_find_panel_or_bridge(np, 0, i, &panel, &bridge);

                /*
                 * If at least one endpoint is -ENODEV, continue probing,
                 * else if at least one endpoint returned an error
                 * (ie -EPROBE_DEFER) then stop probing.
                 */
                if (ret == -ENODEV)
                        continue;
                else if (ret)
                        goto err;

                if (panel) {
                        bridge = drm_panel_bridge_add_typed(panel,
                                                            DRM_MODE_CONNECTOR_DPI);
                        if (IS_ERR(bridge)) {
                                DRM_ERROR("panel-bridge endpoint %d\n", i);
                                ret = PTR_ERR(bridge);
                                goto err;
                        }
                }

                if (bridge) {
                        ret = ltdc_encoder_init(ddev, bridge);
                        if (ret) {
                                if (ret != -EPROBE_DEFER)
                                        DRM_ERROR("init encoder endpoint %d\n", i);
                                goto err;
                        }
                }
        }

        rstc = devm_reset_control_get_exclusive(dev, NULL);

        mutex_init(&ldev->err_lock);

        if (!IS_ERR(rstc)) {
                reset_control_assert(rstc);
                usleep_range(10, 20);
                reset_control_deassert(rstc);
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        ldev->regs = devm_ioremap_resource(dev, res);
        if (IS_ERR(ldev->regs)) {
                DRM_ERROR("Unable to get ltdc registers\n");
                ret = PTR_ERR(ldev->regs);
                goto err;
        }

        /* Disable interrupts */
        reg_clear(ldev->regs, LTDC_IER,
                  IER_LIE | IER_RRIE | IER_FUIE | IER_TERRIE);

        ret = ltdc_get_caps(ddev);
        if (ret) {
                DRM_ERROR("hardware identifier (0x%08x) not supported!\n",
                          ldev->caps.hw_version);
                goto err;
        }

        DRM_DEBUG_DRIVER("ltdc hw version 0x%08x\n", ldev->caps.hw_version);

        for (i = 0; i < ldev->caps.nb_irq; i++) {
                irq = platform_get_irq(pdev, i);
                if (irq < 0) {
                        ret = irq;
                        goto err;
                }

                ret = devm_request_threaded_irq(dev, irq, ltdc_irq,
                                                ltdc_irq_thread, IRQF_ONESHOT,
                                                dev_name(dev), ddev);
                if (ret) {
                        DRM_ERROR("Failed to register LTDC interrupt\n");
                        goto err;
                }

        }

        crtc = devm_kzalloc(dev, sizeof(*crtc), GFP_KERNEL);
        if (!crtc) {
                DRM_ERROR("Failed to allocate crtc\n");
                ret = -ENOMEM;
                goto err;
        }

        ret = ltdc_crtc_init(ddev, crtc);
        if (ret) {
                DRM_ERROR("Failed to init crtc\n");
                goto err;
        }

        ret = drm_vblank_init(ddev, NB_CRTC);
        if (ret) {
                DRM_ERROR("Failed calling drm_vblank_init()\n");
                goto err;
        }

        clk_disable_unprepare(ldev->pixel_clk);

        pinctrl_pm_select_sleep_state(ddev->dev);

        pm_runtime_enable(ddev->dev);

        return 0;
err:
        for (i = 0; i < nb_endpoints; i++)
                drm_of_panel_bridge_remove(ddev->dev->of_node, 0, i);

        clk_disable_unprepare(ldev->pixel_clk);

        return ret;
}

void ltdc_unload(struct drm_device *ddev)
{
        struct device *dev = ddev->dev;
        int nb_endpoints, i;

        DRM_DEBUG_DRIVER("\n");

        nb_endpoints = of_graph_get_endpoint_count(dev->of_node);

        for (i = 0; i < nb_endpoints; i++)
                drm_of_panel_bridge_remove(ddev->dev->of_node, 0, i);

        pm_runtime_disable(ddev->dev);
}

MODULE_AUTHOR("Philippe Cornu <philippe.cornu@st.com>");
MODULE_AUTHOR("Yannick Fertre <yannick.fertre@st.com>");
MODULE_AUTHOR("Fabien Dessenne <fabien.dessenne@st.com>");
MODULE_AUTHOR("Mickael Reulier <mickael.reulier@st.com>");
MODULE_DESCRIPTION("STMicroelectronics ST DRM LTDC driver");
MODULE_LICENSE("GPL v2");