LXR linux/drivers/staging/fbtft/fb

   1// SPDX-License-Identifier: GPL-2.0+
   2/*
   3 * FB driver for the UltraChip UC1611 LCD controller
   4 *
   5 * The display is 4-bit grayscale (16 shades) 240x160.
   6 *
   7 * Copyright (C) 2015 Henri Chain
   8 */
   9
  10#include <linux/module.h>
  11#include <linux/kernel.h>
  12#include <linux/init.h>
  13#include <linux/gpio/consumer.h>
  14#include <linux/spi/spi.h>
  15#include <linux/delay.h>
  16
  17#include "fbtft.h"
  18
  19#define DRVNAME         "fb_uc1611"
  20#define WIDTH           240
  21#define HEIGHT          160
  22#define BPP             8
  23#define FPS             40
  24
  25/*
  26 * LCD voltage is a combination of ratio, gain, pot and temp
  27 *
  28 * V_LCD = V_BIAS * ratio
  29 * V_LCD = (C_V0 + C_PM × pot) * (1 + (T - 25) * temp)
  30 * C_V0 and C_PM depend on ratio and gain
  31 * T is ambient temperature
  32 */
  33
  34/* BR -> actual ratio: 0-3 -> 5, 10, 11, 13 */
  35static unsigned int ratio = 2;
  36module_param(ratio, uint, 0000);
  37MODULE_PARM_DESC(ratio, "BR[1:0] Bias voltage ratio: 0-3 (default: 2)");
  38
  39static unsigned int gain = 3;
  40module_param(gain, uint, 0000);
  41MODULE_PARM_DESC(gain, "GN[1:0] Bias voltage gain: 0-3 (default: 3)");
  42
  43static unsigned int pot = 16;
  44module_param(pot, uint, 0000);
  45MODULE_PARM_DESC(pot, "PM[6:0] Bias voltage pot.: 0-63 (default: 16)");
  46
  47/* TC -> % compensation per deg C: 0-3 -> -.05, -.10, -.015, -.20 */
  48static unsigned int temp;
  49module_param(temp, uint, 0000);
  50MODULE_PARM_DESC(temp, "TC[1:0] Temperature compensation: 0-3 (default: 0)");
  51
  52/* PC[1:0] -> LCD capacitance: 0-3 -> <20nF, 20-28 nF, 29-40 nF, 40-56 nF */
  53static unsigned int load = 1;
  54module_param(load, uint, 0000);
  55MODULE_PARM_DESC(load, "PC[1:0] Panel Loading: 0-3 (default: 1)");
  56
  57/* PC[3:2] -> V_LCD: 0, 1, 3 -> ext., int. with ratio = 5, int. standard */
  58static unsigned int pump = 3;
  59module_param(pump, uint, 0000);
  60MODULE_PARM_DESC(pump, "PC[3:2] Pump control: 0,1,3 (default: 3)");
  61
  62static int init_display(struct fbtft_par *par)
  63{
  64        int ret;
  65
  66        /*
  67         * Set CS active inverse polarity: just setting SPI_CS_HIGH does not
  68         * work with GPIO based chip selects that are logically active high
  69         * but inverted inside the GPIO library, so enforce inverted
  70         * semantics.
  71         */
  72        par->spi->mode ^= SPI_CS_HIGH;
  73        ret = spi_setup(par->spi);
  74        if (ret) {
  75                dev_err(par->info->device,
  76                        "Could not set inverse CS polarity\n");
  77                return ret;
  78        }
  79
  80        /* Reset controller */
  81        write_reg(par, 0xE2);
  82
  83        /* Set bias ratio */
  84        write_reg(par, 0xE8 | (ratio & 0x03));
  85
  86        /* Set bias gain and potentiometer */
  87        write_reg(par, 0x81);
  88        write_reg(par, (gain & 0x03) << 6 | (pot & 0x3F));
  89
  90        /* Set temperature compensation */
  91        write_reg(par, 0x24 | (temp & 0x03));
  92
  93        /* Set panel loading */
  94        write_reg(par, 0x28 | (load & 0x03));
  95
  96        /* Set pump control */
  97        write_reg(par, 0x2C | (pump & 0x03));
  98
  99        /* Set inverse display */
 100        write_reg(par, 0xA6 | 0x01);
 101
 102        /* Set 4-bit grayscale mode */
 103        write_reg(par, 0xD0 | (0x02 & 0x03));
 104
 105        /* Set Display enable */
 106        write_reg(par, 0xA8 | 0x07);
 107
 108        return 0;
 109}
 110
 111static void set_addr_win(struct fbtft_par *par, int xs, int ys, int xe, int ye)
 112{
 113        switch (par->info->var.rotate) {
 114        case 90:
 115        case 270:
 116                /* Set column address */
 117                write_reg(par, ys & 0x0F);
 118                write_reg(par, 0x10 | (ys >> 4));
 119
 120                /* Set page address (divide xs by 2) (not used by driver) */
 121                write_reg(par, 0x60 | ((xs >> 1) & 0x0F));
 122                write_reg(par, 0x70 | (xs >> 5));
 123                break;
 124        default:
 125                /* Set column address (not used by driver) */
 126                write_reg(par, xs & 0x0F);
 127                write_reg(par, 0x10 | (xs >> 4));
 128
 129                /* Set page address (divide ys by 2) */
 130                write_reg(par, 0x60 | ((ys >> 1) & 0x0F));
 131                write_reg(par, 0x70 | (ys >> 5));
 132                break;
 133        }
 134}
 135
 136static int blank(struct fbtft_par *par, bool on)
 137{
 138        fbtft_par_dbg(DEBUG_BLANK, par, "(%s=%s)\n",
 139                      __func__, on ? "true" : "false");
 140
 141        if (on)
 142                write_reg(par, 0xA8 | 0x00);
 143        else
 144                write_reg(par, 0xA8 | 0x07);
 145        return 0;
 146}
 147
 148static int set_var(struct fbtft_par *par)
 149{
 150        /* par->info->fix.visual = FB_VISUAL_PSEUDOCOLOR; */
 151        par->info->var.grayscale = 1;
 152        par->info->var.red.offset    = 0;
 153        par->info->var.red.length    = 8;
 154        par->info->var.green.offset  = 0;
 155        par->info->var.green.length  = 8;
 156        par->info->var.blue.offset   = 0;
 157        par->info->var.blue.length   = 8;
 158        par->info->var.transp.offset = 0;
 159        par->info->var.transp.length = 0;
 160
 161        switch (par->info->var.rotate) {
 162        case 90:
 163                /* Set RAM address control */
 164                write_reg(par, 0x88
 165                        | (0x0 & 0x1) << 2 /* Increment positively */
 166                        | (0x1 << 1)       /* Increment page first */
 167                        | 0x1);            /* Wrap around (default) */
 168
 169                /* Set LCD mapping */
 170                write_reg(par, 0xC0
 171                        | (0x0 & 0x1) << 2 /* Mirror Y OFF */
 172                        | (0x0 & 0x1) << 1 /* Mirror X OFF */
 173                        | (0x0 & 0x1));    /* MS nibble last (default) */
 174                break;
 175        case 180:
 176                /* Set RAM address control */
 177                write_reg(par, 0x88
 178                        | (0x0 & 0x1) << 2 /* Increment positively */
 179                        | (0x0 & 0x1) << 1 /* Increment column first */
 180                        | 0x1);            /* Wrap around (default) */
 181
 182                /* Set LCD mapping */
 183                write_reg(par, 0xC0
 184                        | (0x1 << 2)       /* Mirror Y ON */
 185                        | (0x0 & 0x1) << 1 /* Mirror X OFF */
 186                        | (0x0 & 0x1));    /* MS nibble last (default) */
 187                break;
 188        case 270:
 189                /* Set RAM address control */
 190                write_reg(par, 0x88
 191                        | (0x0 & 0x1) << 2 /* Increment positively */
 192                        | (0x1 << 1)       /* Increment page first */
 193                        | 0x1);            /* Wrap around (default) */
 194
 195                /* Set LCD mapping */
 196                write_reg(par, 0xC0
 197                        | (0x1 << 2)       /* Mirror Y ON */
 198                        | (0x1 << 1)       /* Mirror X ON */
 199                        | (0x0 & 0x1));    /* MS nibble last (default) */
 200                break;
 201        default:
 202                /* Set RAM address control */
 203                write_reg(par, 0x88
 204                        | (0x0 & 0x1) << 2 /* Increment positively */
 205                        | (0x0 & 0x1) << 1 /* Increment column first */
 206                        | 0x1);            /* Wrap around (default) */
 207
 208                /* Set LCD mapping */
 209                write_reg(par, 0xC0
 210                        | (0x0 & 0x1) << 2 /* Mirror Y OFF */
 211                        | (0x1 << 1)       /* Mirror X ON */
 212                        | (0x0 & 0x1));    /* MS nibble last (default) */
 213                break;
 214        }
 215
 216        return 0;
 217}
 218
 219static int write_vmem(struct fbtft_par *par, size_t offset, size_t len)
 220{
 221        u8 *vmem8 = (u8 *)(par->info->screen_buffer);
 222        u8 *buf8 = par->txbuf.buf;
 223        u16 *buf16 = par->txbuf.buf;
 224        int line_length = par->info->fix.line_length;
 225        int y_start = offset / line_length;
 226        int y_end = (offset + len - 1) / line_length;
 227        int x, y, i;
 228        int ret = 0;
 229
 230        switch (par->pdata->display.buswidth) {
 231        case 8:
 232                switch (par->info->var.rotate) {
 233                case 90:
 234                case 270:
 235                        i = y_start * line_length;
 236                        for (y = y_start; y <= y_end; y++) {
 237                                for (x = 0; x < line_length; x += 2) {
 238                                        *buf8 = vmem8[i] >> 4;
 239                                        *buf8 |= vmem8[i + 1] & 0xF0;
 240                                        buf8++;
 241                                        i += 2;
 242                                }
 243                        }
 244                        break;
 245                default:
 246                        /* Must be even because pages are two lines */
 247                        y_start &= 0xFE;
 248                        i = y_start * line_length;
 249                        for (y = y_start; y <= y_end; y += 2) {
 250                                for (x = 0; x < line_length; x++) {
 251                                        *buf8 = vmem8[i] >> 4;
 252                                        *buf8 |= vmem8[i + line_length] & 0xF0;
 253                                        buf8++;
 254                                        i++;
 255                                }
 256                                i += line_length;
 257                        }
 258                        break;
 259                }
 260                gpiod_set_value(par->gpio.dc, 1);
 261
 262                /* Write data */
 263                ret = par->fbtftops.write(par, par->txbuf.buf, len / 2);
 264                break;
 265        case 9:
 266                switch (par->info->var.rotate) {
 267                case 90:
 268                case 270:
 269                        i = y_start * line_length;
 270                        for (y = y_start; y <= y_end; y++) {
 271                                for (x = 0; x < line_length; x += 2) {
 272                                        *buf16 = 0x100;
 273                                        *buf16 |= vmem8[i] >> 4;
 274                                        *buf16 |= vmem8[i + 1] & 0xF0;
 275                                        buf16++;
 276                                        i += 2;
 277                                }
 278                        }
 279                        break;
 280                default:
 281                        /* Must be even because pages are two lines */
 282                        y_start &= 0xFE;
 283                        i = y_start * line_length;
 284                        for (y = y_start; y <= y_end; y += 2) {
 285                                for (x = 0; x < line_length; x++) {
 286                                        *buf16 = 0x100;
 287                                        *buf16 |= vmem8[i] >> 4;
 288                                        *buf16 |= vmem8[i + line_length] & 0xF0;
 289                                        buf16++;
 290                                        i++;
 291                                }
 292                                i += line_length;
 293                        }
 294                        break;
 295                }
 296
 297                /* Write data */
 298                ret = par->fbtftops.write(par, par->txbuf.buf, len);
 299                break;
 300        default:
 301                dev_err(par->info->device, "unsupported buswidth %d\n",
 302                        par->pdata->display.buswidth);
 303        }
 304
 305        if (ret < 0)
 306                dev_err(par->info->device, "write failed and returned: %d\n",
 307                        ret);
 308
 309        return ret;
 310}
 311
 312static struct fbtft_display display = {
 313        .txbuflen = -1,
 314        .regwidth = 8,
 315        .width = WIDTH,
 316        .height = HEIGHT,
 317        .bpp = BPP,
 318        .fps = FPS,
 319        .fbtftops = {
 320                .write_vmem = write_vmem,
 321                .init_display = init_display,
 322                .set_addr_win = set_addr_win,
 323                .set_var = set_var,
 324                .blank = blank,
 325        },
 326};
 327
 328FBTFT_REGISTER_DRIVER(DRVNAME, "ultrachip,uc1611", &display);
 329
 330MODULE_ALIAS("spi:" DRVNAME);
 331MODULE_ALIAS("platform:" DRVNAME);
 332MODULE_ALIAS("spi:uc1611");
 333MODULE_ALIAS("platform:uc1611");
 334
 335MODULE_DESCRIPTION("FB driver for the UC1611 LCD controller");
 336MODULE_AUTHOR("Henri Chain");
 337MODULE_LICENSE("GPL");
 338