// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2013 Noralf Tronnes
 *
 * This driver is inspired by:
 *   st7735fb.c, Copyright (C) 2011, Matt Porter
 *   broadsheetfb.c, Copyright (C) 2008, Jaya Kumar
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/fb.h>
#include <linux/gpio/consumer.h>
#include <linux/spi/spi.h>
#include <linux/delay.h>
#include <linux/uaccess.h>
#include <linux/backlight.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/spinlock.h>

#include <video/mipi_display.h>

#include "fbtft.h"
#include "internal.h"

static unsigned long debug;
module_param(debug, ulong, 0000);
MODULE_PARM_DESC(debug, "override device debug level");

int fbtft_write_buf_dc(struct fbtft_par *par, void *buf, size_t len, int dc)
{
        int ret;

        gpiod_set_value(par->gpio.dc, dc);

        ret = par->fbtftops.write(par, buf, len);
        if (ret < 0)
                dev_err(par->info->device,
                        "write() failed and returned %d\n", ret);
        return ret;
}
EXPORT_SYMBOL(fbtft_write_buf_dc);

void fbtft_dbg_hex(const struct device *dev, int groupsize,
                   const void *buf, size_t len, const char *fmt, ...)
{
        va_list args;
        static char textbuf[512];
        char *text = textbuf;
        size_t text_len;

        va_start(args, fmt);
        text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
        va_end(args);

        hex_dump_to_buffer(buf, len, 32, groupsize, text + text_len,
                           512 - text_len, false);

        if (len > 32)
                dev_info(dev, "%s ...\n", text);
        else
                dev_info(dev, "%s\n", text);
}
EXPORT_SYMBOL(fbtft_dbg_hex);

static int fbtft_request_one_gpio(struct fbtft_par *par,
                                  const char *name, int index,
                                  struct gpio_desc **gpiop)
{
        struct device *dev = par->info->device;

        *gpiop = devm_gpiod_get_index_optional(dev, name, index,
                                               GPIOD_OUT_LOW);
        if (IS_ERR(*gpiop))
                return dev_err_probe(dev, PTR_ERR(*gpiop), "Failed to request %s GPIO\n", name);

        fbtft_par_dbg(DEBUG_REQUEST_GPIOS, par, "%s: '%s' GPIO\n",
                      __func__, name);

        return 0;
}

static int fbtft_request_gpios(struct fbtft_par *par)
{
        int i;
        int ret;

        ret = fbtft_request_one_gpio(par, "reset", 0, &par->gpio.reset);
        if (ret)
                return ret;
        ret = fbtft_request_one_gpio(par, "dc", 0, &par->gpio.dc);
        if (ret)
                return ret;
        ret = fbtft_request_one_gpio(par, "rd", 0, &par->gpio.rd);
        if (ret)
                return ret;
        ret = fbtft_request_one_gpio(par, "wr", 0, &par->gpio.wr);
        if (ret)
                return ret;
        ret = fbtft_request_one_gpio(par, "cs", 0, &par->gpio.cs);
        if (ret)
                return ret;
        ret = fbtft_request_one_gpio(par, "latch", 0, &par->gpio.latch);
        if (ret)
                return ret;
        for (i = 0; i < 16; i++) {
                ret = fbtft_request_one_gpio(par, "db", i,
                                             &par->gpio.db[i]);
                if (ret)
                        return ret;
                ret = fbtft_request_one_gpio(par, "led", i,
                                             &par->gpio.led[i]);
                if (ret)
                        return ret;
                ret = fbtft_request_one_gpio(par, "aux", i,
                                             &par->gpio.aux[i]);
                if (ret)
                        return ret;
        }

        return 0;
}

static int fbtft_backlight_update_status(struct backlight_device *bd)
{
        struct fbtft_par *par = bl_get_data(bd);
        bool polarity = par->polarity;

        fbtft_par_dbg(DEBUG_BACKLIGHT, par, "%s: polarity=%d, power=%d\n", __func__,
                      polarity, bd->props.power);

        if (!backlight_is_blank(bd))
                gpiod_set_value(par->gpio.led[0], polarity);
        else
                gpiod_set_value(par->gpio.led[0], !polarity);

        return 0;
}

static int fbtft_backlight_get_brightness(struct backlight_device *bd)
{
        return bd->props.brightness;
}

void fbtft_unregister_backlight(struct fbtft_par *par)
{
        if (par->info->bl_dev) {
                par->info->bl_dev->props.power = BACKLIGHT_POWER_OFF;
                backlight_update_status(par->info->bl_dev);
                backlight_device_unregister(par->info->bl_dev);
                par->info->bl_dev = NULL;
        }
}
EXPORT_SYMBOL(fbtft_unregister_backlight);

static const struct backlight_ops fbtft_bl_ops = {
        .get_brightness = fbtft_backlight_get_brightness,
        .update_status  = fbtft_backlight_update_status,
};

void fbtft_register_backlight(struct fbtft_par *par)
{
        struct backlight_device *bd;
        struct backlight_properties bl_props = { 0, };

        if (!par->gpio.led[0]) {
                fbtft_par_dbg(DEBUG_BACKLIGHT, par,
                              "%s(): led pin not set, exiting.\n", __func__);
                return;
        }

        bl_props.type = BACKLIGHT_RAW;
        /* Assume backlight is off, get polarity from current state of pin */
        bl_props.power = BACKLIGHT_POWER_OFF;
        if (!gpiod_get_value(par->gpio.led[0]))
                par->polarity = true;

        bd = backlight_device_register(dev_driver_string(par->info->device),
                                       par->info->device, par,
                                       &fbtft_bl_ops, &bl_props);
        if (IS_ERR(bd)) {
                dev_err(par->info->device,
                        "cannot register backlight device (%ld)\n",
                        PTR_ERR(bd));
                return;
        }
        par->info->bl_dev = bd;

        if (!par->fbtftops.unregister_backlight)
                par->fbtftops.unregister_backlight = fbtft_unregister_backlight;
}
EXPORT_SYMBOL(fbtft_register_backlight);

static void fbtft_set_addr_win(struct fbtft_par *par, int xs, int ys, int xe,
                               int ye)
{
        write_reg(par, MIPI_DCS_SET_COLUMN_ADDRESS,
                  (xs >> 8) & 0xFF, xs & 0xFF, (xe >> 8) & 0xFF, xe & 0xFF);

        write_reg(par, MIPI_DCS_SET_PAGE_ADDRESS,
                  (ys >> 8) & 0xFF, ys & 0xFF, (ye >> 8) & 0xFF, ye & 0xFF);

        write_reg(par, MIPI_DCS_WRITE_MEMORY_START);
}

static void fbtft_reset(struct fbtft_par *par)
{
        if (!par->gpio.reset)
                return;

        gpiod_set_value_cansleep(par->gpio.reset, 1);
        usleep_range(20, 40);
        gpiod_set_value_cansleep(par->gpio.reset, 0);
        msleep(120);

        gpiod_set_value_cansleep(par->gpio.cs, 1);  /* Activate chip */
}

static void fbtft_update_display(struct fbtft_par *par, unsigned int start_line,
                                 unsigned int end_line)
{
        size_t offset, len;
        ktime_t ts_start, ts_end;
        long fps, throughput;
        bool timeit = false;
        int ret = 0;

        if (unlikely(par->debug & (DEBUG_TIME_FIRST_UPDATE |
                        DEBUG_TIME_EACH_UPDATE))) {
                if ((par->debug & DEBUG_TIME_EACH_UPDATE) ||
                    ((par->debug & DEBUG_TIME_FIRST_UPDATE) &&
                    !par->first_update_done)) {
                        ts_start = ktime_get();
                        timeit = true;
                }
        }

        /* Sanity checks */
        if (start_line > end_line) {
                dev_warn(par->info->device,
                         "%s: start_line=%u is larger than end_line=%u. Shouldn't happen, will do full display update\n",
                         __func__, start_line, end_line);
                start_line = 0;
                end_line = par->info->var.yres - 1;
        }
        if (start_line > par->info->var.yres - 1 ||
            end_line > par->info->var.yres - 1) {
                dev_warn(par->info->device,
                         "%s: start_line=%u or end_line=%u is larger than max=%d. Shouldn't happen, will do full display update\n",
                         __func__, start_line,
                         end_line, par->info->var.yres - 1);
                start_line = 0;
                end_line = par->info->var.yres - 1;
        }

        fbtft_par_dbg(DEBUG_UPDATE_DISPLAY, par, "%s(start_line=%u, end_line=%u)\n",
                      __func__, start_line, end_line);

        if (par->fbtftops.set_addr_win)
                par->fbtftops.set_addr_win(par, 0, start_line,
                                par->info->var.xres - 1, end_line);

        offset = start_line * par->info->fix.line_length;
        len = (end_line - start_line + 1) * par->info->fix.line_length;
        ret = par->fbtftops.write_vmem(par, offset, len);
        if (ret < 0)
                dev_err(par->info->device,
                        "%s: write_vmem failed to update display buffer\n",
                        __func__);

        if (unlikely(timeit)) {
                ts_end = ktime_get();
                if (!ktime_to_ns(par->update_time))
                        par->update_time = ts_start;

                fps = ktime_us_delta(ts_start, par->update_time);
                par->update_time = ts_start;
                fps = fps ? 1000000 / fps : 0;

                throughput = ktime_us_delta(ts_end, ts_start);
                throughput = throughput ? (len * 1000) / throughput : 0;
                throughput = throughput * 1000 / 1024;

                dev_info(par->info->device,
                         "Display update: %ld kB/s, fps=%ld\n",
                         throughput, fps);
                par->first_update_done = true;
        }
}

static void fbtft_mkdirty(struct fb_info *info, int y, int height)
{
        struct fbtft_par *par = info->par;
        struct fb_deferred_io *fbdefio = info->fbdefio;

        /* special case, needed ? */
        if (y == -1) {
                y = 0;
                height = info->var.yres;
        }

        /* Mark display lines/area as dirty */
        spin_lock(&par->dirty_lock);
        if (y < par->dirty_lines_start)
                par->dirty_lines_start = y;
        if (y + height - 1 > par->dirty_lines_end)
                par->dirty_lines_end = y + height - 1;
        spin_unlock(&par->dirty_lock);

        /* Schedule deferred_io to update display (no-op if already on queue)*/
        schedule_delayed_work(&info->deferred_work, fbdefio->delay);
}

static void fbtft_deferred_io(struct fb_info *info, struct list_head *pagereflist)
{
        struct fbtft_par *par = info->par;
        unsigned int dirty_lines_start, dirty_lines_end;
        struct fb_deferred_io_pageref *pageref;
        unsigned int y_low = 0, y_high = 0;

        spin_lock(&par->dirty_lock);
        dirty_lines_start = par->dirty_lines_start;
        dirty_lines_end = par->dirty_lines_end;
        /* set display line markers as clean */
        par->dirty_lines_start = par->info->var.yres - 1;
        par->dirty_lines_end = 0;
        spin_unlock(&par->dirty_lock);

        /* Mark display lines as dirty */
        list_for_each_entry(pageref, pagereflist, list) {
                y_low = pageref->offset / info->fix.line_length;
                y_high = (pageref->offset + PAGE_SIZE - 1) / info->fix.line_length;
                dev_dbg(info->device, "y_low=%d y_high=%d\n", y_low, y_high);
                if (y_high > info->var.yres - 1)
                        y_high = info->var.yres - 1;
                if (y_low < dirty_lines_start)
                        dirty_lines_start = y_low;
                if (y_high > dirty_lines_end)
                        dirty_lines_end = y_high;
        }

        par->fbtftops.update_display(info->par,
                                        dirty_lines_start, dirty_lines_end);
}

/* from pxafb.c */
static unsigned int chan_to_field(unsigned int chan, struct fb_bitfield *bf)
{
        chan &= 0xffff;
        chan >>= 16 - bf->length;
        return chan << bf->offset;
}

static int fbtft_fb_setcolreg(unsigned int regno, unsigned int red,
                              unsigned int green, unsigned int blue,
                              unsigned int transp, struct fb_info *info)
{
        unsigned int val;
        int ret = 1;

        fb_dbg(info,
               "regno=%u, red=0x%X, green=0x%X, blue=0x%X, trans=0x%X\n",
               regno, red, green, blue, transp);

        switch (info->fix.visual) {
        case FB_VISUAL_TRUECOLOR:
                if (regno < 16) {
                        u32 *pal = info->pseudo_palette;

                        val  = chan_to_field(red,   &info->var.red);
                        val |= chan_to_field(green, &info->var.green);
                        val |= chan_to_field(blue,  &info->var.blue);

                        pal[regno] = val;
                        ret = 0;
                }
                break;
        }
        return ret;
}

static int fbtft_fb_blank(int blank, struct fb_info *info)
{
        struct fbtft_par *par = info->par;
        int ret = -EINVAL;

        fb_dbg(info, "blank=%d\n", blank);

        if (!par->fbtftops.blank)
                return ret;

        switch (blank) {
        case FB_BLANK_POWERDOWN:
        case FB_BLANK_VSYNC_SUSPEND:
        case FB_BLANK_HSYNC_SUSPEND:
        case FB_BLANK_NORMAL:
                ret = par->fbtftops.blank(par, true);
                break;
        case FB_BLANK_UNBLANK:
                ret = par->fbtftops.blank(par, false);
                break;
        }
        return ret;
}

static void fbtft_ops_damage_range(struct fb_info *info, off_t off, size_t len)
{
        struct fbtft_par *par = info->par;

        /* TODO: only mark changed area update all for now */
        par->fbtftops.mkdirty(info, -1, 0);
}

static void fbtft_ops_damage_area(struct fb_info *info, u32 x, u32 y, u32 width, u32 height)
{
        struct fbtft_par *par = info->par;

        par->fbtftops.mkdirty(info, y, height);
}

FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(fbtft_ops,
                                   fbtft_ops_damage_range,
                                   fbtft_ops_damage_area)

static const struct fb_ops fbtft_ops = {
        .owner        = THIS_MODULE,
        FB_DEFAULT_DEFERRED_OPS(fbtft_ops),
        .fb_setcolreg = fbtft_fb_setcolreg,
        .fb_blank     = fbtft_fb_blank,
};

static void fbtft_merge_fbtftops(struct fbtft_ops *dst, struct fbtft_ops *src)
{
        if (src->write)
                dst->write = src->write;
        if (src->read)
                dst->read = src->read;
        if (src->write_vmem)
                dst->write_vmem = src->write_vmem;
        if (src->write_register)
                dst->write_register = src->write_register;
        if (src->set_addr_win)
                dst->set_addr_win = src->set_addr_win;
        if (src->reset)
                dst->reset = src->reset;
        if (src->mkdirty)
                dst->mkdirty = src->mkdirty;
        if (src->update_display)
                dst->update_display = src->update_display;
        if (src->init_display)
                dst->init_display = src->init_display;
        if (src->blank)
                dst->blank = src->blank;
        if (src->request_gpios_match)
                dst->request_gpios_match = src->request_gpios_match;
        if (src->request_gpios)
                dst->request_gpios = src->request_gpios;
        if (src->verify_gpios)
                dst->verify_gpios = src->verify_gpios;
        if (src->register_backlight)
                dst->register_backlight = src->register_backlight;
        if (src->unregister_backlight)
                dst->unregister_backlight = src->unregister_backlight;
        if (src->set_var)
                dst->set_var = src->set_var;
        if (src->set_gamma)
                dst->set_gamma = src->set_gamma;
}

/**
 * fbtft_framebuffer_alloc - creates a new frame buffer info structure
 *
 * @display: pointer to structure describing the display
 * @dev: pointer to the device for this fb, this can be NULL
 * @pdata: platform data for the display in use
 *
 * Creates a new frame buffer info structure.
 *
 * Also creates and populates the following structures:
 *   info->fbdefio
 *   info->pseudo_palette
 *   par->fbtftops
 *   par->txbuf
 *
 * Returns the new structure, or NULL if an error occurred.
 *
 */
struct fb_info *fbtft_framebuffer_alloc(struct fbtft_display *display,
                                        struct device *dev,
                                        struct fbtft_platform_data *pdata)
{
        struct fb_info *info;
        struct fbtft_par *par;
        struct fb_deferred_io *fbdefio = NULL;
        u8 *vmem = NULL;
        void *txbuf = NULL;
        void *buf = NULL;
        unsigned int width;
        unsigned int height;
        int txbuflen = display->txbuflen;
        unsigned int bpp = display->bpp;
        unsigned int fps = display->fps;
        int vmem_size;
        const s16 *init_sequence = display->init_sequence;
        char *gamma = display->gamma;
        u32 *gamma_curves = NULL;

        /* sanity check */
        if (display->gamma_num * display->gamma_len >
                        FBTFT_GAMMA_MAX_VALUES_TOTAL) {
                dev_err(dev, "FBTFT_GAMMA_MAX_VALUES_TOTAL=%d is exceeded\n",
                        FBTFT_GAMMA_MAX_VALUES_TOTAL);
                return NULL;
        }

        /* defaults */
        if (!fps)
                fps = 20;
        if (!bpp)
                bpp = 16;

        if (!pdata) {
                dev_err(dev, "platform data is missing\n");
                return NULL;
        }

        /* override driver values? */
        if (pdata->fps)
                fps = pdata->fps;
        if (pdata->txbuflen)
                txbuflen = pdata->txbuflen;
        if (pdata->display.init_sequence)
                init_sequence = pdata->display.init_sequence;
        if (pdata->gamma)
                gamma = pdata->gamma;
        if (pdata->display.debug)
                display->debug = pdata->display.debug;
        if (pdata->display.backlight)
                display->backlight = pdata->display.backlight;
        if (pdata->display.width)
                display->width = pdata->display.width;
        if (pdata->display.height)
                display->height = pdata->display.height;
        if (pdata->display.buswidth)
                display->buswidth = pdata->display.buswidth;
        if (pdata->display.regwidth)
                display->regwidth = pdata->display.regwidth;

        display->debug |= debug;
        fbtft_expand_debug_value(&display->debug);

        switch (pdata->rotate) {
        case 90:
        case 270:
                width =  display->height;
                height = display->width;
                break;
        default:
                width =  display->width;
                height = display->height;
        }

        fbdefio = devm_kzalloc(dev, sizeof(struct fb_deferred_io), GFP_KERNEL);
        if (!fbdefio)
                return NULL;

        buf = devm_kzalloc(dev, 128, GFP_KERNEL);
        if (!buf)
                return NULL;

        if (display->gamma_num && display->gamma_len) {
                gamma_curves = devm_kcalloc(dev,
                                            display->gamma_num *
                                            display->gamma_len,
                                            sizeof(gamma_curves[0]),
                                            GFP_KERNEL);
                if (!gamma_curves)
                        return NULL;
        }

        info = framebuffer_alloc(sizeof(struct fbtft_par), dev);
        if (!info)
                return NULL;

        vmem_size = display->width * display->height * bpp / 8;
        vmem = vzalloc(vmem_size);
        if (!vmem)
                goto release_framebuf;

        info->screen_buffer = vmem;
        info->fbops = &fbtft_ops;
        info->fbdefio = fbdefio;

        fbdefio->delay =            HZ / fps;
        fbdefio->sort_pagereflist = true;
        fbdefio->deferred_io =      fbtft_deferred_io;

        snprintf(info->fix.id, sizeof(info->fix.id), "%s", dev->driver->name);
        info->fix.type =           FB_TYPE_PACKED_PIXELS;
        info->fix.visual =         FB_VISUAL_TRUECOLOR;
        info->fix.xpanstep =       0;
        info->fix.ypanstep =       0;
        info->fix.ywrapstep =      0;
        info->fix.line_length =    width * bpp / 8;
        info->fix.accel =          FB_ACCEL_NONE;
        info->fix.smem_len =       vmem_size;
        if (fb_deferred_io_init(info))
                goto release_screen_buffer;

        info->var.rotate =         pdata->rotate;
        info->var.xres =           width;
        info->var.yres =           height;
        info->var.xres_virtual =   info->var.xres;
        info->var.yres_virtual =   info->var.yres;
        info->var.bits_per_pixel = bpp;
        info->var.nonstd =         1;

        /* RGB565 */
        info->var.red.offset =     11;
        info->var.red.length =     5;
        info->var.green.offset =   5;
        info->var.green.length =   6;
        info->var.blue.offset =    0;
        info->var.blue.length =    5;
        info->var.transp.offset =  0;
        info->var.transp.length =  0;

        info->flags =              FBINFO_VIRTFB;

        par = info->par;
        par->info = info;
        par->pdata = pdata;
        par->debug = display->debug;
        par->buf = buf;
        spin_lock_init(&par->dirty_lock);
        par->bgr = pdata->bgr;
        par->startbyte = pdata->startbyte;
        par->init_sequence = init_sequence;
        par->gamma.curves = gamma_curves;
        par->gamma.num_curves = display->gamma_num;
        par->gamma.num_values = display->gamma_len;
        mutex_init(&par->gamma.lock);
        info->pseudo_palette = par->pseudo_palette;

        if (par->gamma.curves && gamma) {
                if (fbtft_gamma_parse_str(par, par->gamma.curves, gamma,
                                          strlen(gamma)))
                        goto cleanup_deferred;
        }

        /* Transmit buffer */
        if (txbuflen == -1)
                txbuflen = vmem_size + 2; /* add in case startbyte is used */
        if (txbuflen >= vmem_size + 2)
                txbuflen = 0;

#ifdef __LITTLE_ENDIAN
        if ((!txbuflen) && (bpp > 8))
                txbuflen = PAGE_SIZE; /* need buffer for byteswapping */
#endif

        if (txbuflen > 0) {
                txbuf = kzalloc(txbuflen, GFP_KERNEL);
                if (!txbuf)
                        goto cleanup_deferred;
                par->txbuf.buf = txbuf;
                par->txbuf.len = txbuflen;
        }

        /* default fbtft operations */
        par->fbtftops.write = fbtft_write_spi;
        par->fbtftops.read = fbtft_read_spi;
        par->fbtftops.write_vmem = fbtft_write_vmem16_bus8;
        par->fbtftops.write_register = fbtft_write_reg8_bus8;
        par->fbtftops.set_addr_win = fbtft_set_addr_win;
        par->fbtftops.reset = fbtft_reset;
        par->fbtftops.mkdirty = fbtft_mkdirty;
        par->fbtftops.update_display = fbtft_update_display;
        if (display->backlight)
                par->fbtftops.register_backlight = fbtft_register_backlight;

        /* use driver provided functions */
        fbtft_merge_fbtftops(&par->fbtftops, &display->fbtftops);

        return info;

cleanup_deferred:
        fb_deferred_io_cleanup(info);
release_screen_buffer:
        vfree(info->screen_buffer);
release_framebuf:
        framebuffer_release(info);
        return NULL;
}
EXPORT_SYMBOL(fbtft_framebuffer_alloc);

/**
 * fbtft_framebuffer_release - frees up all memory used by the framebuffer
 *
 * @info: frame buffer info structure
 *
 */
void fbtft_framebuffer_release(struct fb_info *info)
{
        struct fbtft_par *par = info->par;

        kfree(par->txbuf.buf);
        fb_deferred_io_cleanup(info);
        vfree(info->screen_buffer);
        framebuffer_release(info);
}
EXPORT_SYMBOL(fbtft_framebuffer_release);

/**
 *      fbtft_register_framebuffer - registers a tft frame buffer device
 *      @fb_info: frame buffer info structure
 *
 *  Sets SPI driverdata if needed
 *  Requests needed gpios.
 *  Initializes display
 *  Updates display.
 *      Registers a frame buffer device @fb_info.
 *
 *      Returns negative errno on error, or zero for success.
 *
 */
int fbtft_register_framebuffer(struct fb_info *fb_info)
{
        int ret;
        char text1[50] = "";
        char text2[50] = "";
        struct fbtft_par *par = fb_info->par;
        struct spi_device *spi = par->spi;

        /* sanity checks */
        if (!par->fbtftops.init_display) {
                dev_err(fb_info->device, "missing fbtftops.init_display()\n");
                return -EINVAL;
        }

        if (spi)
                spi_set_drvdata(spi, fb_info);
        if (par->pdev)
                platform_set_drvdata(par->pdev, fb_info);

        ret = par->fbtftops.request_gpios(par);
        if (ret < 0)
                goto reg_fail;

        if (par->fbtftops.verify_gpios) {
                ret = par->fbtftops.verify_gpios(par);
                if (ret < 0)
                        goto reg_fail;
        }

        ret = par->fbtftops.init_display(par);
        if (ret < 0)
                goto reg_fail;
        if (par->fbtftops.set_var) {
                ret = par->fbtftops.set_var(par);
                if (ret < 0)
                        goto reg_fail;
        }

        /* update the entire display */
        par->fbtftops.update_display(par, 0, par->info->var.yres - 1);

        if (par->fbtftops.set_gamma && par->gamma.curves) {
                ret = par->fbtftops.set_gamma(par, par->gamma.curves);
                if (ret)
                        goto reg_fail;
        }

        if (par->fbtftops.register_backlight)
                par->fbtftops.register_backlight(par);

        ret = register_framebuffer(fb_info);
        if (ret < 0)
                goto reg_fail;

        fbtft_sysfs_init(par);

        if (par->txbuf.buf && par->txbuf.len >= 1024)
                sprintf(text1, ", %zu KiB buffer memory", par->txbuf.len >> 10);
        if (spi)
                sprintf(text2, ", spi%d.%d at %d MHz", spi->controller->bus_num,
                        spi_get_chipselect(spi, 0), spi->max_speed_hz / 1000000);
        fb_dbg(fb_info,
               "%s frame buffer, %dx%d, %d KiB video memory%s, fps=%lu%s\n",
               fb_info->fix.id, fb_info->var.xres, fb_info->var.yres,
               fb_info->fix.smem_len >> 10, text1,
               HZ / fb_info->fbdefio->delay, text2);

        /* Turn on backlight if available */
        if (fb_info->bl_dev) {
                fb_info->bl_dev->props.power = BACKLIGHT_POWER_ON;
                fb_info->bl_dev->ops->update_status(fb_info->bl_dev);
        }

        return 0;

reg_fail:
        if (par->fbtftops.unregister_backlight)
                par->fbtftops.unregister_backlight(par);

        return ret;
}
EXPORT_SYMBOL(fbtft_register_framebuffer);

/**
 *      fbtft_unregister_framebuffer - releases a tft frame buffer device
 *      @fb_info: frame buffer info structure
 *
 *  Frees SPI driverdata if needed
 *  Frees gpios.
 *      Unregisters frame buffer device.
 *
 */
int fbtft_unregister_framebuffer(struct fb_info *fb_info)
{
        struct fbtft_par *par = fb_info->par;

        if (par->fbtftops.unregister_backlight)
                par->fbtftops.unregister_backlight(par);
        fbtft_sysfs_exit(par);
        unregister_framebuffer(fb_info);

        return 0;
}
EXPORT_SYMBOL(fbtft_unregister_framebuffer);

/**
 * fbtft_init_display_from_property() - Device Tree init_display() function
 * @par: Driver data
 *
 * Return: 0 if successful, negative if error
 */
static int fbtft_init_display_from_property(struct fbtft_par *par)
{
        struct device *dev = par->info->device;
        int buf[64], count, index, i, j, ret;
        u32 *values;
        u32 val;

        count = device_property_count_u32(dev, "init");
        if (count < 0)
                return count;
        if (count == 0)
                return -EINVAL;

        values = kmalloc_array(count + 1, sizeof(*values), GFP_KERNEL);
        if (!values)
                return -ENOMEM;

        ret = device_property_read_u32_array(dev, "init", values, count);
        if (ret)
                goto out_free;

        par->fbtftops.reset(par);

        index = -1;
        val = values[++index];

        while (index < count) {
                if (val & FBTFT_OF_INIT_CMD) {
                        val &= 0xFFFF;
                        i = 0;
                        while ((index < count) && !(val & 0xFFFF0000)) {
                                if (i > 63) {
                                        dev_err(dev,
                                                "%s: Maximum register values exceeded\n",
                                                __func__);
                                        ret = -EINVAL;
                                        goto out_free;
                                }
                                buf[i++] = val;
                                val = values[++index];
                        }
                        /* make debug message */
                        fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
                                      "init: write_register:\n");
                        for (j = 0; j < i; j++)
                                fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
                                              "buf[%d] = %02X\n", j, buf[j]);

                        par->fbtftops.write_register(par, i,
                                buf[0], buf[1], buf[2], buf[3],
                                buf[4], buf[5], buf[6], buf[7],
                                buf[8], buf[9], buf[10], buf[11],
                                buf[12], buf[13], buf[14], buf[15],
                                buf[16], buf[17], buf[18], buf[19],
                                buf[20], buf[21], buf[22], buf[23],
                                buf[24], buf[25], buf[26], buf[27],
                                buf[28], buf[29], buf[30], buf[31],
                                buf[32], buf[33], buf[34], buf[35],
                                buf[36], buf[37], buf[38], buf[39],
                                buf[40], buf[41], buf[42], buf[43],
                                buf[44], buf[45], buf[46], buf[47],
                                buf[48], buf[49], buf[50], buf[51],
                                buf[52], buf[53], buf[54], buf[55],
                                buf[56], buf[57], buf[58], buf[59],
                                buf[60], buf[61], buf[62], buf[63]);
                } else if (val & FBTFT_OF_INIT_DELAY) {
                        fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
                                      "init: msleep(%u)\n", val & 0xFFFF);
                        msleep(val & 0xFFFF);
                        val = values[++index];
                } else {
                        dev_err(dev, "illegal init value 0x%X\n", val);
                        ret = -EINVAL;
                        goto out_free;
                }
        }

out_free:
        kfree(values);
        return ret;
}

/**
 * fbtft_init_display() - Generic init_display() function
 * @par: Driver data
 *
 * Uses par->init_sequence to do the initialization
 *
 * Return: 0 if successful, negative if error
 */
int fbtft_init_display(struct fbtft_par *par)
{
        int buf[64];
        int i;
        int j;

        /* sanity check */
        if (!par->init_sequence) {
                dev_err(par->info->device,
                        "error: init_sequence is not set\n");
                return -EINVAL;
        }

        /* make sure stop marker exists */
        for (i = 0; i < FBTFT_MAX_INIT_SEQUENCE; i++) {
                if (par->init_sequence[i] == -3)
                        break;
        }

        if (i == FBTFT_MAX_INIT_SEQUENCE) {
                dev_err(par->info->device,
                        "missing stop marker at end of init sequence\n");
                return -EINVAL;
        }

        par->fbtftops.reset(par);

        i = 0;
        while (i < FBTFT_MAX_INIT_SEQUENCE) {
                if (par->init_sequence[i] == -3) {
                        /* done */
                        return 0;
                }
                if (par->init_sequence[i] >= 0) {
                        dev_err(par->info->device,
                                "missing delimiter at position %d\n", i);
                        return -EINVAL;
                }
                if (par->init_sequence[i + 1] < 0) {
                        dev_err(par->info->device,
                                "missing value after delimiter %d at position %d\n",
                                par->init_sequence[i], i);
                        return -EINVAL;
                }
                switch (par->init_sequence[i]) {
                case -1:
                        i++;

                        /* make debug message */
                        for (j = 0; par->init_sequence[i + 1 + j] >= 0; j++)
                                ;

                        fbtft_par_dbg_hex(DEBUG_INIT_DISPLAY, par, par->info->device,
                                          s16, &par->init_sequence[i + 1], j,
                                          "init: write(0x%02X)", par->init_sequence[i]);

                        /* Write */
                        j = 0;
                        while (par->init_sequence[i] >= 0) {
                                if (j > 63) {
                                        dev_err(par->info->device,
                                                "%s: Maximum register values exceeded\n",
                                                __func__);
                                        return -EINVAL;
                                }
                                buf[j++] = par->init_sequence[i++];
                        }
                        par->fbtftops.write_register(par, j,
                                buf[0], buf[1], buf[2], buf[3],
                                buf[4], buf[5], buf[6], buf[7],
                                buf[8], buf[9], buf[10], buf[11],
                                buf[12], buf[13], buf[14], buf[15],
                                buf[16], buf[17], buf[18], buf[19],
                                buf[20], buf[21], buf[22], buf[23],
                                buf[24], buf[25], buf[26], buf[27],
                                buf[28], buf[29], buf[30], buf[31],
                                buf[32], buf[33], buf[34], buf[35],
                                buf[36], buf[37], buf[38], buf[39],
                                buf[40], buf[41], buf[42], buf[43],
                                buf[44], buf[45], buf[46], buf[47],
                                buf[48], buf[49], buf[50], buf[51],
                                buf[52], buf[53], buf[54], buf[55],
                                buf[56], buf[57], buf[58], buf[59],
                                buf[60], buf[61], buf[62], buf[63]);
                        break;
                case -2:
                        i++;
                        fbtft_par_dbg(DEBUG_INIT_DISPLAY, par,
                                      "init: mdelay(%d)\n",
                                      par->init_sequence[i]);
                        mdelay(par->init_sequence[i++]);
                        break;
                default:
                        dev_err(par->info->device,
                                "unknown delimiter %d at position %d\n",
                                par->init_sequence[i], i);
                        return -EINVAL;
                }
        }

        dev_err(par->info->device,
                "%s: something is wrong. Shouldn't get here.\n", __func__);
        return -EINVAL;
}
EXPORT_SYMBOL(fbtft_init_display);

/**
 * fbtft_verify_gpios() - Generic verify_gpios() function
 * @par: Driver data
 *
 * Uses @spi, @pdev and @buswidth to determine which GPIOs is needed
 *
 * Return: 0 if successful, negative if error
 */
static int fbtft_verify_gpios(struct fbtft_par *par)
{
        struct fbtft_platform_data *pdata = par->pdata;
        int i;

        if (pdata->display.buswidth != 9 &&  par->startbyte == 0 &&
            !par->gpio.dc) {
                dev_err(par->info->device,
                        "Missing info about 'dc' gpio. Aborting.\n");
                return -EINVAL;
        }

        if (!par->pdev)
                return 0;

        if (!par->gpio.wr) {
                dev_err(par->info->device, "Missing 'wr' gpio. Aborting.\n");
                return -EINVAL;
        }
        for (i = 0; i < pdata->display.buswidth; i++) {
                if (!par->gpio.db[i]) {
                        dev_err(par->info->device,
                                "Missing 'db%02d' gpio. Aborting.\n", i);
                        return -EINVAL;
                }
        }

        return 0;
}

/* returns 0 if the property is not present */
static u32 fbtft_property_value(struct device *dev, const char *propname)
{
        int ret;
        u32 val = 0;

        ret = device_property_read_u32(dev, propname, &val);
        if (ret == 0)
                dev_info(dev, "%s: %s = %u\n", __func__, propname, val);

        return val;
}

static struct fbtft_platform_data *fbtft_properties_read(struct device *dev)
{
        struct fbtft_platform_data *pdata;

        if (!dev_fwnode(dev)) {
                dev_err(dev, "Missing platform data or properties\n");
                return ERR_PTR(-EINVAL);
        }

        pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
        if (!pdata)
                return ERR_PTR(-ENOMEM);

        pdata->display.width = fbtft_property_value(dev, "width");
        pdata->display.height = fbtft_property_value(dev, "height");
        pdata->display.regwidth = fbtft_property_value(dev, "regwidth");
        pdata->display.buswidth = fbtft_property_value(dev, "buswidth");
        pdata->display.backlight = fbtft_property_value(dev, "backlight");
        pdata->display.bpp = fbtft_property_value(dev, "bpp");
        pdata->display.debug = fbtft_property_value(dev, "debug");
        pdata->rotate = fbtft_property_value(dev, "rotate");
        pdata->bgr = device_property_read_bool(dev, "bgr");
        pdata->fps = fbtft_property_value(dev, "fps");
        pdata->txbuflen = fbtft_property_value(dev, "txbuflen");
        pdata->startbyte = fbtft_property_value(dev, "startbyte");
        device_property_read_string(dev, "gamma", (const char **)&pdata->gamma);

        if (device_property_present(dev, "led-gpios"))
                pdata->display.backlight = 1;
        if (device_property_present(dev, "init"))
                pdata->display.fbtftops.init_display =
                        fbtft_init_display_from_property;

        pdata->display.fbtftops.request_gpios = fbtft_request_gpios;

        return pdata;
}

/**
 * fbtft_probe_common() - Generic device probe() helper function
 * @display: Display properties
 * @sdev: SPI device
 * @pdev: Platform device
 *
 * Allocates, initializes and registers a framebuffer
 *
 * Either @sdev or @pdev should be NULL
 *
 * Return: 0 if successful, negative if error
 */
int fbtft_probe_common(struct fbtft_display *display,
                       struct spi_device *sdev,
                       struct platform_device *pdev)
{
        struct device *dev;
        struct fb_info *info;
        struct fbtft_par *par;
        struct fbtft_platform_data *pdata;
        int ret;

        if (sdev)
                dev = &sdev->dev;
        else
                dev = &pdev->dev;

        pdata = dev->platform_data;
        if (!pdata) {
                pdata = fbtft_properties_read(dev);
                if (IS_ERR(pdata))
                        return PTR_ERR(pdata);
        }

        info = fbtft_framebuffer_alloc(display, dev, pdata);
        if (!info)
                return -ENOMEM;

        par = info->par;
        par->spi = sdev;
        par->pdev = pdev;

        if (display->buswidth == 0) {
                ret = dev_err_probe(dev, -EINVAL, "buswidth is not set\n");
                goto out_release;
        }

        /* write register functions */
        if (display->regwidth == 8 && display->buswidth == 8)
                par->fbtftops.write_register = fbtft_write_reg8_bus8;
        else if (display->regwidth == 8 && display->buswidth == 9 && par->spi)
                par->fbtftops.write_register = fbtft_write_reg8_bus9;
        else if (display->regwidth == 16 && display->buswidth == 8)
                par->fbtftops.write_register = fbtft_write_reg16_bus8;
        else if (display->regwidth == 16 && display->buswidth == 16)
                par->fbtftops.write_register = fbtft_write_reg16_bus16;
        else
                dev_warn(dev,
                         "no default functions for regwidth=%d and buswidth=%d\n",
                         display->regwidth, display->buswidth);

        /* write_vmem() functions */
        if (display->buswidth == 8)
                par->fbtftops.write_vmem = fbtft_write_vmem16_bus8;
        else if (display->buswidth == 9)
                par->fbtftops.write_vmem = fbtft_write_vmem16_bus9;
        else if (display->buswidth == 16)
                par->fbtftops.write_vmem = fbtft_write_vmem16_bus16;

        /* GPIO write() functions */
        if (par->pdev) {
                if (display->buswidth == 8)
                        par->fbtftops.write = fbtft_write_gpio8_wr;
                else if (display->buswidth == 16)
                        par->fbtftops.write = fbtft_write_gpio16_wr;
        }

        /* 9-bit SPI setup */
        if (par->spi && display->buswidth == 9) {
                if (par->spi->controller->bits_per_word_mask & SPI_BPW_MASK(9)) {
                        par->spi->bits_per_word = 9;
                } else {
                        dev_warn(&par->spi->dev,
                                 "9-bit SPI not available, emulating using 8-bit.\n");
                        /* allocate buffer with room for dc bits */
                        par->extra = devm_kzalloc(par->info->device,
                                                  par->txbuf.len +
                                                  (par->txbuf.len / 8) + 8,
                                                  GFP_KERNEL);
                        if (!par->extra) {
                                ret = -ENOMEM;
                                goto out_release;
                        }
                        par->fbtftops.write = fbtft_write_spi_emulate_9;
                }
        }

        if (!par->fbtftops.verify_gpios)
                par->fbtftops.verify_gpios = fbtft_verify_gpios;

        /* make sure we still use the driver provided functions */
        fbtft_merge_fbtftops(&par->fbtftops, &display->fbtftops);

        /* use init_sequence if provided */
        if (par->init_sequence)
                par->fbtftops.init_display = fbtft_init_display;

        /* use platform_data provided functions above all */
        fbtft_merge_fbtftops(&par->fbtftops, &pdata->display.fbtftops);

        ret = fbtft_register_framebuffer(info);
        if (ret < 0)
                goto out_release;

        return 0;

out_release:
        fbtft_framebuffer_release(info);

        return ret;
}
EXPORT_SYMBOL(fbtft_probe_common);

/**
 * fbtft_remove_common() - Generic device remove() helper function
 * @dev: Device
 * @info: Framebuffer
 *
 * Unregisters and releases the framebuffer
 */
void fbtft_remove_common(struct device *dev, struct fb_info *info)
{
        struct fbtft_par *par;

        par = info->par;
        if (par)
                fbtft_par_dbg(DEBUG_DRIVER_INIT_FUNCTIONS, par,
                              "%s()\n", __func__);
        fbtft_unregister_framebuffer(info);
        fbtft_framebuffer_release(info);
}
EXPORT_SYMBOL(fbtft_remove_common);

MODULE_DESCRIPTION("Core FB support for small TFT LCD display modules");
MODULE_LICENSE("GPL");