drivers/gpu/drm/tiny/repaper.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * DRM driver for Pervasive Displays RePaper branded e-ink panels
   4  *
   5  * Copyright 2013-2017 Pervasive Displays, Inc.
   6  * Copyright 2017 Noralf Trønnes
   7  *
   8  * The driver supports:
   9  * Material Film: Aurora Mb (V231)
  10  * Driver IC: G2 (eTC)
  11  *
  12  * The controller code was taken from the userspace driver:
  13  * https://github.com/repaper/gratis
  14  */
  15
  16 #include <linux/delay.h>
  17 #include <linux/dma-buf.h>
  18 #include <linux/gpio/consumer.h>
  19 #include <linux/module.h>
  20 #include <linux/property.h>
  21 #include <linux/sched/clock.h>
  22 #include <linux/spi/spi.h>
  23 #include <linux/thermal.h>
  24
  25 #include <drm/drm_atomic_helper.h>
  26 #include <drm/drm_connector.h>
  27 #include <drm/drm_damage_helper.h>
  28 #include <drm/drm_drv.h>
  29 #include <drm/drm_fb_cma_helper.h>
  30 #include <drm/drm_fb_helper.h>
  31 #include <drm/drm_format_helper.h>
  32 #include <drm/drm_gem_cma_helper.h>
  33 #include <drm/drm_gem_framebuffer_helper.h>
  34 #include <drm/drm_managed.h>
  35 #include <drm/drm_modes.h>
  36 #include <drm/drm_rect.h>
  37 #include <drm/drm_probe_helper.h>
  38 #include <drm/drm_simple_kms_helper.h>
  39
  40 #define REPAPER_RID_G2_COG_ID   0x12
  41
  42 enum repaper_model {
  43         /* 0 is reserved to avoid clashing with NULL */
  44         E1144CS021 = 1,
  45         E1190CS021,
  46         E2200CS021,
  47         E2271CS021,
  48 };
  49
  50 enum repaper_stage {         /* Image pixel -> Display pixel */
  51         REPAPER_COMPENSATE,  /* B -> W, W -> B (Current Image) */
  52         REPAPER_WHITE,       /* B -> N, W -> W (Current Image) */
  53         REPAPER_INVERSE,     /* B -> N, W -> B (New Image) */
  54         REPAPER_NORMAL       /* B -> B, W -> W (New Image) */
  55 };
  56
  57 enum repaper_epd_border_byte {
  58         REPAPER_BORDER_BYTE_NONE,
  59         REPAPER_BORDER_BYTE_ZERO,
  60         REPAPER_BORDER_BYTE_SET,
  61 };
  62
  63 struct repaper_epd {
  64         struct drm_device drm;
  65         struct drm_simple_display_pipe pipe;
  66         const struct drm_display_mode *mode;
  67         struct drm_connector connector;
  68         struct spi_device *spi;
  69
  70         struct gpio_desc *panel_on;
  71         struct gpio_desc *border;
  72         struct gpio_desc *discharge;
  73         struct gpio_desc *reset;
  74         struct gpio_desc *busy;
  75
  76         struct thermal_zone_device *thermal;
  77
  78         unsigned int height;
  79         unsigned int width;
  80         unsigned int bytes_per_scan;
  81         const u8 *channel_select;
  82         unsigned int stage_time;
  83         unsigned int factored_stage_time;
  84         bool middle_scan;
  85         bool pre_border_byte;
  86         enum repaper_epd_border_byte border_byte;
  87
  88         u8 *line_buffer;
  89         void *current_frame;
  90
  91         bool cleared;
  92         bool partial;
  93 };
  94
  95 static inline struct repaper_epd *drm_to_epd(struct drm_device *drm)
  96 {
  97         return container_of(drm, struct repaper_epd, drm);
  98 }
  99
 100 static int repaper_spi_transfer(struct spi_device *spi, u8 header,
 101                                 const void *tx, void *rx, size_t len)
 102 {
 103         void *txbuf = NULL, *rxbuf = NULL;
 104         struct spi_transfer tr[2] = {};
 105         u8 *headerbuf;
 106         int ret;
 107
 108         headerbuf = kmalloc(1, GFP_KERNEL);
 109         if (!headerbuf)
 110                 return -ENOMEM;
 111
 112         headerbuf[0] = header;
 113         tr[0].tx_buf = headerbuf;
 114         tr[0].len = 1;
 115
 116         /* Stack allocated tx? */
 117         if (tx && len <= 32) {
 118                 txbuf = kmemdup(tx, len, GFP_KERNEL);
 119                 if (!txbuf) {
 120                         ret = -ENOMEM;
 121                         goto out_free;
 122                 }
 123         }
 124
 125         if (rx) {
 126                 rxbuf = kmalloc(len, GFP_KERNEL);
 127                 if (!rxbuf) {
 128                         ret = -ENOMEM;
 129                         goto out_free;
 130                 }
 131         }
 132
 133         tr[1].tx_buf = txbuf ? txbuf : tx;
 134         tr[1].rx_buf = rxbuf;
 135         tr[1].len = len;
 136
 137         ndelay(80);
 138         ret = spi_sync_transfer(spi, tr, 2);
 139         if (rx && !ret)
 140                 memcpy(rx, rxbuf, len);
 141
 142 out_free:
 143         kfree(headerbuf);
 144         kfree(txbuf);
 145         kfree(rxbuf);
 146
 147         return ret;
 148 }
 149
 150 static int repaper_write_buf(struct spi_device *spi, u8 reg,
 151                              const u8 *buf, size_t len)
 152 {
 153         int ret;
 154
 155         ret = repaper_spi_transfer(spi, 0x70, &reg, NULL, 1);
 156         if (ret)
 157                 return ret;
 158
 159         return repaper_spi_transfer(spi, 0x72, buf, NULL, len);
 160 }
 161
 162 static int repaper_write_val(struct spi_device *spi, u8 reg, u8 val)
 163 {
 164         return repaper_write_buf(spi, reg, &val, 1);
 165 }
 166
 167 static int repaper_read_val(struct spi_device *spi, u8 reg)
 168 {
 169         int ret;
 170         u8 val;
 171
 172         ret = repaper_spi_transfer(spi, 0x70, &reg, NULL, 1);
 173         if (ret)
 174                 return ret;
 175
 176         ret = repaper_spi_transfer(spi, 0x73, NULL, &val, 1);
 177
 178         return ret ? ret : val;
 179 }
 180
 181 static int repaper_read_id(struct spi_device *spi)
 182 {
 183         int ret;
 184         u8 id;
 185
 186         ret = repaper_spi_transfer(spi, 0x71, NULL, &id, 1);
 187
 188         return ret ? ret : id;
 189 }
 190
 191 static void repaper_spi_mosi_low(struct spi_device *spi)
 192 {
 193         const u8 buf[1] = { 0 };
 194
 195         spi_write(spi, buf, 1);
 196 }
 197
 198 /* pixels on display are numbered from 1 so even is actually bits 1,3,5,... */
 199 static void repaper_even_pixels(struct repaper_epd *epd, u8 **pp,
 200                                 const u8 *data, u8 fixed_value, const u8 *mask,
 201                                 enum repaper_stage stage)
 202 {
 203         unsigned int b;
 204
 205         for (b = 0; b < (epd->width / 8); b++) {
 206                 if (data) {
 207                         u8 pixels = data[b] & 0xaa;
 208                         u8 pixel_mask = 0xff;
 209                         u8 p1, p2, p3, p4;
 210
 211                         if (mask) {
 212                                 pixel_mask = (mask[b] ^ pixels) & 0xaa;
 213                                 pixel_mask |= pixel_mask >> 1;
 214                         }
 215
 216                         switch (stage) {
 217                         case REPAPER_COMPENSATE: /* B -> W, W -> B (Current) */
 218                                 pixels = 0xaa | ((pixels ^ 0xaa) >> 1);
 219                                 break;
 220                         case REPAPER_WHITE:      /* B -> N, W -> W (Current) */
 221                                 pixels = 0x55 + ((pixels ^ 0xaa) >> 1);
 222                                 break;
 223                         case REPAPER_INVERSE:    /* B -> N, W -> B (New) */
 224                                 pixels = 0x55 | (pixels ^ 0xaa);
 225                                 break;
 226                         case REPAPER_NORMAL:     /* B -> B, W -> W (New) */
 227                                 pixels = 0xaa | (pixels >> 1);
 228                                 break;
 229                         }
 230
 231                         pixels = (pixels & pixel_mask) | (~pixel_mask & 0x55);
 232                         p1 = (pixels >> 6) & 0x03;
 233                         p2 = (pixels >> 4) & 0x03;
 234                         p3 = (pixels >> 2) & 0x03;
 235                         p4 = (pixels >> 0) & 0x03;
 236                         pixels = (p1 << 0) | (p2 << 2) | (p3 << 4) | (p4 << 6);
 237                         *(*pp)++ = pixels;
 238                 } else {
 239                         *(*pp)++ = fixed_value;
 240                 }
 241         }
 242 }
 243
 244 /* pixels on display are numbered from 1 so odd is actually bits 0,2,4,... */
 245 static void repaper_odd_pixels(struct repaper_epd *epd, u8 **pp,
 246                                const u8 *data, u8 fixed_value, const u8 *mask,
 247                                enum repaper_stage stage)
 248 {
 249         unsigned int b;
 250
 251         for (b = epd->width / 8; b > 0; b--) {
 252                 if (data) {
 253                         u8 pixels = data[b - 1] & 0x55;
 254                         u8 pixel_mask = 0xff;
 255
 256                         if (mask) {
 257                                 pixel_mask = (mask[b - 1] ^ pixels) & 0x55;
 258                                 pixel_mask |= pixel_mask << 1;
 259                         }
 260
 261                         switch (stage) {
 262                         case REPAPER_COMPENSATE: /* B -> W, W -> B (Current) */
 263                                 pixels = 0xaa | (pixels ^ 0x55);
 264                                 break;
 265                         case REPAPER_WHITE:      /* B -> N, W -> W (Current) */
 266                                 pixels = 0x55 + (pixels ^ 0x55);
 267                                 break;
 268                         case REPAPER_INVERSE:    /* B -> N, W -> B (New) */
 269                                 pixels = 0x55 | ((pixels ^ 0x55) << 1);
 270                                 break;
 271                         case REPAPER_NORMAL:     /* B -> B, W -> W (New) */
 272                                 pixels = 0xaa | pixels;
 273                                 break;
 274                         }
 275
 276                         pixels = (pixels & pixel_mask) | (~pixel_mask & 0x55);
 277                         *(*pp)++ = pixels;
 278                 } else {
 279                         *(*pp)++ = fixed_value;
 280                 }
 281         }
 282 }
 283
 284 /* interleave bits: (byte)76543210 -> (16 bit).7.6.5.4.3.2.1 */
 285 static inline u16 repaper_interleave_bits(u16 value)
 286 {
 287         value = (value | (value << 4)) & 0x0f0f;
 288         value = (value | (value << 2)) & 0x3333;
 289         value = (value | (value << 1)) & 0x5555;
 290
 291         return value;
 292 }
 293
 294 /* pixels on display are numbered from 1 */
 295 static void repaper_all_pixels(struct repaper_epd *epd, u8 **pp,
 296                                const u8 *data, u8 fixed_value, const u8 *mask,
 297                                enum repaper_stage stage)
 298 {
 299         unsigned int b;
 300
 301         for (b = epd->width / 8; b > 0; b--) {
 302                 if (data) {
 303                         u16 pixels = repaper_interleave_bits(data[b - 1]);
 304                         u16 pixel_mask = 0xffff;
 305
 306                         if (mask) {
 307                                 pixel_mask = repaper_interleave_bits(mask[b - 1]);
 308
 309                                 pixel_mask = (pixel_mask ^ pixels) & 0x5555;
 310                                 pixel_mask |= pixel_mask << 1;
 311                         }
 312
 313                         switch (stage) {
 314                         case REPAPER_COMPENSATE: /* B -> W, W -> B (Current) */
 315                                 pixels = 0xaaaa | (pixels ^ 0x5555);
 316                                 break;
 317                         case REPAPER_WHITE:      /* B -> N, W -> W (Current) */
 318                                 pixels = 0x5555 + (pixels ^ 0x5555);
 319                                 break;
 320                         case REPAPER_INVERSE:    /* B -> N, W -> B (New) */
 321                                 pixels = 0x5555 | ((pixels ^ 0x5555) << 1);
 322                                 break;
 323                         case REPAPER_NORMAL:     /* B -> B, W -> W (New) */
 324                                 pixels = 0xaaaa | pixels;
 325                                 break;
 326                         }
 327
 328                         pixels = (pixels & pixel_mask) | (~pixel_mask & 0x5555);
 329                         *(*pp)++ = pixels >> 8;
 330                         *(*pp)++ = pixels;
 331                 } else {
 332                         *(*pp)++ = fixed_value;
 333                         *(*pp)++ = fixed_value;
 334                 }
 335         }
 336 }
 337
 338 /* output one line of scan and data bytes to the display */
 339 static void repaper_one_line(struct repaper_epd *epd, unsigned int line,
 340                              const u8 *data, u8 fixed_value, const u8 *mask,
 341                              enum repaper_stage stage)
 342 {
 343         u8 *p = epd->line_buffer;
 344         unsigned int b;
 345
 346         repaper_spi_mosi_low(epd->spi);
 347
 348         if (epd->pre_border_byte)
 349                 *p++ = 0x00;
 350
 351         if (epd->middle_scan) {
 352                 /* data bytes */
 353                 repaper_odd_pixels(epd, &p, data, fixed_value, mask, stage);
 354
 355                 /* scan line */
 356                 for (b = epd->bytes_per_scan; b > 0; b--) {
 357                         if (line / 4 == b - 1)
 358                                 *p++ = 0x03 << (2 * (line & 0x03));
 359                         else
 360                                 *p++ = 0x00;
 361                 }
 362
 363                 /* data bytes */
 364                 repaper_even_pixels(epd, &p, data, fixed_value, mask, stage);
 365         } else {
 366                 /*
 367                  * even scan line, but as lines on display are numbered from 1,
 368                  * line: 1,3,5,...
 369                  */
 370                 for (b = 0; b < epd->bytes_per_scan; b++) {
 371                         if (0 != (line & 0x01) && line / 8 == b)
 372                                 *p++ = 0xc0 >> (line & 0x06);
 373                         else
 374                                 *p++ = 0x00;
 375                 }
 376
 377                 /* data bytes */
 378                 repaper_all_pixels(epd, &p, data, fixed_value, mask, stage);
 379
 380                 /*
 381                  * odd scan line, but as lines on display are numbered from 1,
 382                  * line: 0,2,4,6,...
 383                  */
 384                 for (b = epd->bytes_per_scan; b > 0; b--) {
 385                         if (0 == (line & 0x01) && line / 8 == b - 1)
 386                                 *p++ = 0x03 << (line & 0x06);
 387                         else
 388                                 *p++ = 0x00;
 389                 }
 390         }
 391
 392         switch (epd->border_byte) {
 393         case REPAPER_BORDER_BYTE_NONE:
 394                 break;
 395
 396         case REPAPER_BORDER_BYTE_ZERO:
 397                 *p++ = 0x00;
 398                 break;
 399
 400         case REPAPER_BORDER_BYTE_SET:
 401                 switch (stage) {
 402                 case REPAPER_COMPENSATE:
 403                 case REPAPER_WHITE:
 404                 case REPAPER_INVERSE:
 405                         *p++ = 0x00;
 406                         break;
 407                 case REPAPER_NORMAL:
 408                         *p++ = 0xaa;
 409                         break;
 410                 }
 411                 break;
 412         }
 413
 414         repaper_write_buf(epd->spi, 0x0a, epd->line_buffer,
 415                           p - epd->line_buffer);
 416
 417         /* Output data to panel */
 418         repaper_write_val(epd->spi, 0x02, 0x07);
 419
 420         repaper_spi_mosi_low(epd->spi);
 421 }
 422
 423 static void repaper_frame_fixed(struct repaper_epd *epd, u8 fixed_value,
 424                                 enum repaper_stage stage)
 425 {
 426         unsigned int line;
 427
 428         for (line = 0; line < epd->height; line++)
 429                 repaper_one_line(epd, line, NULL, fixed_value, NULL, stage);
 430 }
 431
 432 static void repaper_frame_data(struct repaper_epd *epd, const u8 *image,
 433                                const u8 *mask, enum repaper_stage stage)
 434 {
 435         unsigned int line;
 436
 437         if (!mask) {
 438                 for (line = 0; line < epd->height; line++) {
 439                         repaper_one_line(epd, line,
 440                                          &image[line * (epd->width / 8)],
 441                                          0, NULL, stage);
 442                 }
 443         } else {
 444                 for (line = 0; line < epd->height; line++) {
 445                         size_t n = line * epd->width / 8;
 446
 447                         repaper_one_line(epd, line, &image[n], 0, &mask[n],
 448                                          stage);
 449                 }
 450         }
 451 }
 452
 453 static void repaper_frame_fixed_repeat(struct repaper_epd *epd, u8 fixed_value,
 454                                        enum repaper_stage stage)
 455 {
 456         u64 start = local_clock();
 457         u64 end = start + (epd->factored_stage_time * 1000 * 1000);
 458
 459         do {
 460                 repaper_frame_fixed(epd, fixed_value, stage);
 461         } while (local_clock() < end);
 462 }
 463
 464 static void repaper_frame_data_repeat(struct repaper_epd *epd, const u8 *image,
 465                                       const u8 *mask, enum repaper_stage stage)
 466 {
 467         u64 start = local_clock();
 468         u64 end = start + (epd->factored_stage_time * 1000 * 1000);
 469
 470         do {
 471                 repaper_frame_data(epd, image, mask, stage);
 472         } while (local_clock() < end);
 473 }
 474
 475 static void repaper_get_temperature(struct repaper_epd *epd)
 476 {
 477         int ret, temperature = 0;
 478         unsigned int factor10x;
 479
 480         if (!epd->thermal)
 481                 return;
 482
 483         ret = thermal_zone_get_temp(epd->thermal, &temperature);
 484         if (ret) {
 485                 DRM_DEV_ERROR(&epd->spi->dev, "Failed to get temperature (%d)\n", ret);
 486                 return;
 487         }
 488
 489         temperature /= 1000;
 490
 491         if (temperature <= -10)
 492                 factor10x = 170;
 493         else if (temperature <= -5)
 494                 factor10x = 120;
 495         else if (temperature <= 5)
 496                 factor10x = 80;
 497         else if (temperature <= 10)
 498                 factor10x = 40;
 499         else if (temperature <= 15)
 500                 factor10x = 30;
 501         else if (temperature <= 20)
 502                 factor10x = 20;
 503         else if (temperature <= 40)
 504                 factor10x = 10;
 505         else
 506                 factor10x = 7;
 507
 508         epd->factored_stage_time = epd->stage_time * factor10x / 10;
 509 }
 510
 511 static void repaper_gray8_to_mono_reversed(u8 *buf, u32 width, u32 height)
 512 {
 513         u8 *gray8 = buf, *mono = buf;
 514         int y, xb, i;
 515
 516         for (y = 0; y < height; y++)
 517                 for (xb = 0; xb < width / 8; xb++) {
 518                         u8 byte = 0x00;
 519
 520                         for (i = 0; i < 8; i++) {
 521                                 int x = xb * 8 + i;
 522
 523                                 byte >>= 1;
 524                                 if (gray8[y * width + x] >> 7)
 525                                         byte |= BIT(7);
 526                         }
 527                         *mono++ = byte;
 528                 }
 529 }
 530
 531 static int repaper_fb_dirty(struct drm_framebuffer *fb)
 532 {
 533         struct drm_gem_cma_object *cma_obj = drm_fb_cma_get_gem_obj(fb, 0);
 534         struct dma_buf_attachment *import_attach = cma_obj->base.import_attach;
 535         struct repaper_epd *epd = drm_to_epd(fb->dev);
 536         struct drm_rect clip;
 537         int idx, ret = 0;
 538         u8 *buf = NULL;
 539
 540         if (!drm_dev_enter(fb->dev, &idx))
 541                 return -ENODEV;
 542
 543         /* repaper can't do partial updates */
 544         clip.x1 = 0;
 545         clip.x2 = fb->width;
 546         clip.y1 = 0;
 547         clip.y2 = fb->height;
 548
 549         repaper_get_temperature(epd);
 550
 551         DRM_DEBUG("Flushing [FB:%d] st=%ums\n", fb->base.id,
 552                   epd->factored_stage_time);
 553
 554         buf = kmalloc_array(fb->width, fb->height, GFP_KERNEL);
 555         if (!buf) {
 556                 ret = -ENOMEM;
 557                 goto out_exit;
 558         }
 559
 560         if (import_attach) {
 561                 ret = dma_buf_begin_cpu_access(import_attach->dmabuf,
 562                                                DMA_FROM_DEVICE);
 563                 if (ret)
 564                         goto out_free;
 565         }
 566
 567         drm_fb_xrgb8888_to_gray8(buf, cma_obj->vaddr, fb, &clip);
 568
 569         if (import_attach) {
 570                 ret = dma_buf_end_cpu_access(import_attach->dmabuf,
 571                                              DMA_FROM_DEVICE);
 572                 if (ret)
 573                         goto out_free;
 574         }
 575
 576         repaper_gray8_to_mono_reversed(buf, fb->width, fb->height);
 577
 578         if (epd->partial) {
 579                 repaper_frame_data_repeat(epd, buf, epd->current_frame,
 580                                           REPAPER_NORMAL);
 581         } else if (epd->cleared) {
 582                 repaper_frame_data_repeat(epd, epd->current_frame, NULL,
 583                                           REPAPER_COMPENSATE);
 584                 repaper_frame_data_repeat(epd, epd->current_frame, NULL,
 585                                           REPAPER_WHITE);
 586                 repaper_frame_data_repeat(epd, buf, NULL, REPAPER_INVERSE);
 587                 repaper_frame_data_repeat(epd, buf, NULL, REPAPER_NORMAL);
 588
 589                 epd->partial = true;
 590         } else {
 591                 /* Clear display (anything -> white) */
 592                 repaper_frame_fixed_repeat(epd, 0xff, REPAPER_COMPENSATE);
 593                 repaper_frame_fixed_repeat(epd, 0xff, REPAPER_WHITE);
 594                 repaper_frame_fixed_repeat(epd, 0xaa, REPAPER_INVERSE);
 595                 repaper_frame_fixed_repeat(epd, 0xaa, REPAPER_NORMAL);
 596
 597                 /* Assuming a clear (white) screen output an image */
 598                 repaper_frame_fixed_repeat(epd, 0xaa, REPAPER_COMPENSATE);
 599                 repaper_frame_fixed_repeat(epd, 0xaa, REPAPER_WHITE);
 600                 repaper_frame_data_repeat(epd, buf, NULL, REPAPER_INVERSE);
 601                 repaper_frame_data_repeat(epd, buf, NULL, REPAPER_NORMAL);
 602
 603                 epd->cleared = true;
 604                 epd->partial = true;
 605         }
 606
 607         memcpy(epd->current_frame, buf, fb->width * fb->height / 8);
 608
 609         /*
 610          * An extra frame write is needed if pixels are set in the bottom line,
 611          * or else grey lines rises up from the pixels
 612          */
 613         if (epd->pre_border_byte) {
 614                 unsigned int x;
 615
 616                 for (x = 0; x < (fb->width / 8); x++)
 617                         if (buf[x + (fb->width * (fb->height - 1) / 8)]) {
 618                                 repaper_frame_data_repeat(epd, buf,
 619                                                           epd->current_frame,
 620                                                           REPAPER_NORMAL);
 621                                 break;
 622                         }
 623         }
 624
 625 out_free:
 626         kfree(buf);
 627 out_exit:
 628         drm_dev_exit(idx);
 629
 630         return ret;
 631 }
 632
 633 static void power_off(struct repaper_epd *epd)
 634 {
 635         /* Turn off power and all signals */
 636         gpiod_set_value_cansleep(epd->reset, 0);
 637         gpiod_set_value_cansleep(epd->panel_on, 0);
 638         if (epd->border)
 639                 gpiod_set_value_cansleep(epd->border, 0);
 640
 641         /* Ensure SPI MOSI and CLOCK are Low before CS Low */
 642         repaper_spi_mosi_low(epd->spi);
 643
 644         /* Discharge pulse */
 645         gpiod_set_value_cansleep(epd->discharge, 1);
 646         msleep(150);
 647         gpiod_set_value_cansleep(epd->discharge, 0);
 648 }
 649
 650 static void repaper_pipe_enable(struct drm_simple_display_pipe *pipe,
 651                                 struct drm_crtc_state *crtc_state,
 652                                 struct drm_plane_state *plane_state)
 653 {
 654         struct repaper_epd *epd = drm_to_epd(pipe->crtc.dev);
 655         struct spi_device *spi = epd->spi;
 656         struct device *dev = &spi->dev;
 657         bool dc_ok = false;
 658         int i, ret, idx;
 659
 660         if (!drm_dev_enter(pipe->crtc.dev, &idx))
 661                 return;
 662
 663         DRM_DEBUG_DRIVER("\n");
 664
 665         /* Power up sequence */
 666         gpiod_set_value_cansleep(epd->reset, 0);
 667         gpiod_set_value_cansleep(epd->panel_on, 0);
 668         gpiod_set_value_cansleep(epd->discharge, 0);
 669         if (epd->border)
 670                 gpiod_set_value_cansleep(epd->border, 0);
 671         repaper_spi_mosi_low(spi);
 672         usleep_range(5000, 10000);
 673
 674         gpiod_set_value_cansleep(epd->panel_on, 1);
 675         /*
 676          * This delay comes from the repaper.org userspace driver, it's not
 677          * mentioned in the datasheet.
 678          */
 679         usleep_range(10000, 15000);
 680         gpiod_set_value_cansleep(epd->reset, 1);
 681         if (epd->border)
 682                 gpiod_set_value_cansleep(epd->border, 1);
 683         usleep_range(5000, 10000);
 684         gpiod_set_value_cansleep(epd->reset, 0);
 685         usleep_range(5000, 10000);
 686         gpiod_set_value_cansleep(epd->reset, 1);
 687         usleep_range(5000, 10000);
 688
 689         /* Wait for COG to become ready */
 690         for (i = 100; i > 0; i--) {
 691                 if (!gpiod_get_value_cansleep(epd->busy))
 692                         break;
 693
 694                 usleep_range(10, 100);
 695         }
 696
 697         if (!i) {
 698                 DRM_DEV_ERROR(dev, "timeout waiting for panel to become ready.\n");
 699                 power_off(epd);
 700                 goto out_exit;
 701         }
 702
 703         repaper_read_id(spi);
 704         ret = repaper_read_id(spi);
 705         if (ret != REPAPER_RID_G2_COG_ID) {
 706                 if (ret < 0)
 707                         dev_err(dev, "failed to read chip (%d)\n", ret);
 708                 else
 709                         dev_err(dev, "wrong COG ID 0x%02x\n", ret);
 710                 power_off(epd);
 711                 goto out_exit;
 712         }
 713
 714         /* Disable OE */
 715         repaper_write_val(spi, 0x02, 0x40);
 716
 717         ret = repaper_read_val(spi, 0x0f);
 718         if (ret < 0 || !(ret & 0x80)) {
 719                 if (ret < 0)
 720                         DRM_DEV_ERROR(dev, "failed to read chip (%d)\n", ret);
 721                 else
 722                         DRM_DEV_ERROR(dev, "panel is reported broken\n");
 723                 power_off(epd);
 724                 goto out_exit;
 725         }
 726
 727         /* Power saving mode */
 728         repaper_write_val(spi, 0x0b, 0x02);
 729         /* Channel select */
 730         repaper_write_buf(spi, 0x01, epd->channel_select, 8);
 731         /* High power mode osc */
 732         repaper_write_val(spi, 0x07, 0xd1);
 733         /* Power setting */
 734         repaper_write_val(spi, 0x08, 0x02);
 735         /* Vcom level */
 736         repaper_write_val(spi, 0x09, 0xc2);
 737         /* Power setting */
 738         repaper_write_val(spi, 0x04, 0x03);
 739         /* Driver latch on */
 740         repaper_write_val(spi, 0x03, 0x01);
 741         /* Driver latch off */
 742         repaper_write_val(spi, 0x03, 0x00);
 743         usleep_range(5000, 10000);
 744
 745         /* Start chargepump */
 746         for (i = 0; i < 4; ++i) {
 747                 /* Charge pump positive voltage on - VGH/VDL on */
 748                 repaper_write_val(spi, 0x05, 0x01);
 749                 msleep(240);
 750
 751                 /* Charge pump negative voltage on - VGL/VDL on */
 752                 repaper_write_val(spi, 0x05, 0x03);
 753                 msleep(40);
 754
 755                 /* Charge pump Vcom on - Vcom driver on */
 756                 repaper_write_val(spi, 0x05, 0x0f);
 757                 msleep(40);
 758
 759                 /* check DC/DC */
 760                 ret = repaper_read_val(spi, 0x0f);
 761                 if (ret < 0) {
 762                         DRM_DEV_ERROR(dev, "failed to read chip (%d)\n", ret);
 763                         power_off(epd);
 764                         goto out_exit;
 765                 }
 766
 767                 if (ret & 0x40) {
 768                         dc_ok = true;
 769                         break;
 770                 }
 771         }
 772
 773         if (!dc_ok) {
 774                 DRM_DEV_ERROR(dev, "dc/dc failed\n");
 775                 power_off(epd);
 776                 goto out_exit;
 777         }
 778
 779         /*
 780          * Output enable to disable
 781          * The userspace driver sets this to 0x04, but the datasheet says 0x06
 782          */
 783         repaper_write_val(spi, 0x02, 0x04);
 784
 785         epd->partial = false;
 786 out_exit:
 787         drm_dev_exit(idx);
 788 }
 789
 790 static void repaper_pipe_disable(struct drm_simple_display_pipe *pipe)
 791 {
 792         struct repaper_epd *epd = drm_to_epd(pipe->crtc.dev);
 793         struct spi_device *spi = epd->spi;
 794         unsigned int line;
 795
 796         /*
 797          * This callback is not protected by drm_dev_enter/exit since we want to
 798          * turn off the display on regular driver unload. It's highly unlikely
 799          * that the underlying SPI controller is gone should this be called after
 800          * unplug.
 801          */
 802
 803         DRM_DEBUG_DRIVER("\n");
 804
 805         /* Nothing frame */
 806         for (line = 0; line < epd->height; line++)
 807                 repaper_one_line(epd, 0x7fffu, NULL, 0x00, NULL,
 808                                  REPAPER_COMPENSATE);
 809
 810         /* 2.7" */
 811         if (epd->border) {
 812                 /* Dummy line */
 813                 repaper_one_line(epd, 0x7fffu, NULL, 0x00, NULL,
 814                                  REPAPER_COMPENSATE);
 815                 msleep(25);
 816                 gpiod_set_value_cansleep(epd->border, 0);
 817                 msleep(200);
 818                 gpiod_set_value_cansleep(epd->border, 1);
 819         } else {
 820                 /* Border dummy line */
 821                 repaper_one_line(epd, 0x7fffu, NULL, 0x00, NULL,
 822                                  REPAPER_NORMAL);
 823                 msleep(200);
 824         }
 825
 826         /* not described in datasheet */
 827         repaper_write_val(spi, 0x0b, 0x00);
 828         /* Latch reset turn on */
 829         repaper_write_val(spi, 0x03, 0x01);
 830         /* Power off charge pump Vcom */
 831         repaper_write_val(spi, 0x05, 0x03);
 832         /* Power off charge pump neg voltage */
 833         repaper_write_val(spi, 0x05, 0x01);
 834         msleep(120);
 835         /* Discharge internal */
 836         repaper_write_val(spi, 0x04, 0x80);
 837         /* turn off all charge pumps */
 838         repaper_write_val(spi, 0x05, 0x00);
 839         /* Turn off osc */
 840         repaper_write_val(spi, 0x07, 0x01);
 841         msleep(50);
 842
 843         power_off(epd);
 844 }
 845
 846 static void repaper_pipe_update(struct drm_simple_display_pipe *pipe,
 847                                 struct drm_plane_state *old_state)
 848 {
 849         struct drm_plane_state *state = pipe->plane.state;
 850         struct drm_rect rect;
 851
 852         if (!pipe->crtc.state->active)
 853                 return;
 854
 855         if (drm_atomic_helper_damage_merged(old_state, state, &rect))
 856                 repaper_fb_dirty(state->fb);
 857 }
 858
 859 static const struct drm_simple_display_pipe_funcs repaper_pipe_funcs = {
 860         .enable = repaper_pipe_enable,
 861         .disable = repaper_pipe_disable,
 862         .update = repaper_pipe_update,
 863         .prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
 864 };
 865
 866 static int repaper_connector_get_modes(struct drm_connector *connector)
 867 {
 868         struct repaper_epd *epd = drm_to_epd(connector->dev);
 869         struct drm_display_mode *mode;
 870
 871         mode = drm_mode_duplicate(connector->dev, epd->mode);
 872         if (!mode) {
 873                 DRM_ERROR("Failed to duplicate mode\n");
 874                 return 0;
 875         }
 876
 877         drm_mode_set_name(mode);
 878         mode->type |= DRM_MODE_TYPE_PREFERRED;
 879         drm_mode_probed_add(connector, mode);
 880
 881         connector->display_info.width_mm = mode->width_mm;
 882         connector->display_info.height_mm = mode->height_mm;
 883
 884         return 1;
 885 }
 886
 887 static const struct drm_connector_helper_funcs repaper_connector_hfuncs = {
 888         .get_modes = repaper_connector_get_modes,
 889 };
 890
 891 static const struct drm_connector_funcs repaper_connector_funcs = {
 892         .reset = drm_atomic_helper_connector_reset,
 893         .fill_modes = drm_helper_probe_single_connector_modes,
 894         .destroy = drm_connector_cleanup,
 895         .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 896         .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
 897 };
 898
 899 static const struct drm_mode_config_funcs repaper_mode_config_funcs = {
 900         .fb_create = drm_gem_fb_create_with_dirty,
 901         .atomic_check = drm_atomic_helper_check,
 902         .atomic_commit = drm_atomic_helper_commit,
 903 };
 904
 905 static const uint32_t repaper_formats[] = {
 906         DRM_FORMAT_XRGB8888,
 907 };
 908
 909 static const struct drm_display_mode repaper_e1144cs021_mode = {
 910         DRM_SIMPLE_MODE(128, 96, 29, 22),
 911 };
 912
 913 static const u8 repaper_e1144cs021_cs[] = { 0x00, 0x00, 0x00, 0x00,
 914                                             0x00, 0x0f, 0xff, 0x00 };
 915
 916 static const struct drm_display_mode repaper_e1190cs021_mode = {
 917         DRM_SIMPLE_MODE(144, 128, 36, 32),
 918 };
 919
 920 static const u8 repaper_e1190cs021_cs[] = { 0x00, 0x00, 0x00, 0x03,
 921                                             0xfc, 0x00, 0x00, 0xff };
 922
 923 static const struct drm_display_mode repaper_e2200cs021_mode = {
 924         DRM_SIMPLE_MODE(200, 96, 46, 22),
 925 };
 926
 927 static const u8 repaper_e2200cs021_cs[] = { 0x00, 0x00, 0x00, 0x00,
 928                                             0x01, 0xff, 0xe0, 0x00 };
 929
 930 static const struct drm_display_mode repaper_e2271cs021_mode = {
 931         DRM_SIMPLE_MODE(264, 176, 57, 38),
 932 };
 933
 934 static const u8 repaper_e2271cs021_cs[] = { 0x00, 0x00, 0x00, 0x7f,
 935                                             0xff, 0xfe, 0x00, 0x00 };
 936
 937 DEFINE_DRM_GEM_CMA_FOPS(repaper_fops);
 938
 939 static struct drm_driver repaper_driver = {
 940         .driver_features        = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
 941         .fops                   = &repaper_fops,
 942         DRM_GEM_CMA_DRIVER_OPS_VMAP,
 943         .name                   = "repaper",
 944         .desc                   = "Pervasive Displays RePaper e-ink panels",
 945         .date                   = "20170405",
 946         .major                  = 1,
 947         .minor                  = 0,
 948 };
 949
 950 static const struct of_device_id repaper_of_match[] = {
 951         { .compatible = "pervasive,e1144cs021", .data = (void *)E1144CS021 },
 952         { .compatible = "pervasive,e1190cs021", .data = (void *)E1190CS021 },
 953         { .compatible = "pervasive,e2200cs021", .data = (void *)E2200CS021 },
 954         { .compatible = "pervasive,e2271cs021", .data = (void *)E2271CS021 },
 955         {},
 956 };
 957 MODULE_DEVICE_TABLE(of, repaper_of_match);
 958
 959 static const struct spi_device_id repaper_id[] = {
 960         { "e1144cs021", E1144CS021 },
 961         { "e1190cs021", E1190CS021 },
 962         { "e2200cs021", E2200CS021 },
 963         { "e2271cs021", E2271CS021 },
 964         { },
 965 };
 966 MODULE_DEVICE_TABLE(spi, repaper_id);
 967
 968 static int repaper_probe(struct spi_device *spi)
 969 {
 970         const struct drm_display_mode *mode;
 971         const struct spi_device_id *spi_id;
 972         struct device *dev = &spi->dev;
 973         enum repaper_model model;
 974         const char *thermal_zone;
 975         struct repaper_epd *epd;
 976         size_t line_buffer_size;
 977         struct drm_device *drm;
 978         const void *match;
 979         int ret;
 980
 981         match = device_get_match_data(dev);
 982         if (match) {
 983                 model = (enum repaper_model)match;
 984         } else {
 985                 spi_id = spi_get_device_id(spi);
 986                 model = (enum repaper_model)spi_id->driver_data;
 987         }
 988
 989         /* The SPI device is used to allocate dma memory */
 990         if (!dev->coherent_dma_mask) {
 991                 ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
 992                 if (ret) {
 993                         dev_warn(dev, "Failed to set dma mask %d\n", ret);
 994                         return ret;
 995                 }
 996         }
 997
 998         epd = devm_drm_dev_alloc(dev, &repaper_driver,
 999                                  struct repaper_epd, drm);
1000         if (IS_ERR(epd))
1001                 return PTR_ERR(epd);
1002
1003         drm = &epd->drm;
1004
1005         ret = drmm_mode_config_init(drm);
1006         if (ret)
1007                 return ret;
1008         drm->mode_config.funcs = &repaper_mode_config_funcs;
1009
1010         epd->spi = spi;
1011
1012         epd->panel_on = devm_gpiod_get(dev, "panel-on", GPIOD_OUT_LOW);
1013         if (IS_ERR(epd->panel_on)) {
1014                 ret = PTR_ERR(epd->panel_on);
1015                 if (ret != -EPROBE_DEFER)
1016                         DRM_DEV_ERROR(dev, "Failed to get gpio 'panel-on'\n");
1017                 return ret;
1018         }
1019
1020         epd->discharge = devm_gpiod_get(dev, "discharge", GPIOD_OUT_LOW);
1021         if (IS_ERR(epd->discharge)) {
1022                 ret = PTR_ERR(epd->discharge);
1023                 if (ret != -EPROBE_DEFER)
1024                         DRM_DEV_ERROR(dev, "Failed to get gpio 'discharge'\n");
1025                 return ret;
1026         }
1027
1028         epd->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
1029         if (IS_ERR(epd->reset)) {
1030                 ret = PTR_ERR(epd->reset);
1031                 if (ret != -EPROBE_DEFER)
1032                         DRM_DEV_ERROR(dev, "Failed to get gpio 'reset'\n");
1033                 return ret;
1034         }
1035
1036         epd->busy = devm_gpiod_get(dev, "busy", GPIOD_IN);
1037         if (IS_ERR(epd->busy)) {
1038                 ret = PTR_ERR(epd->busy);
1039                 if (ret != -EPROBE_DEFER)
1040                         DRM_DEV_ERROR(dev, "Failed to get gpio 'busy'\n");
1041                 return ret;
1042         }
1043
1044         if (!device_property_read_string(dev, "pervasive,thermal-zone",
1045                                          &thermal_zone)) {
1046                 epd->thermal = thermal_zone_get_zone_by_name(thermal_zone);
1047                 if (IS_ERR(epd->thermal)) {
1048                         DRM_DEV_ERROR(dev, "Failed to get thermal zone: %s\n", thermal_zone);
1049                         return PTR_ERR(epd->thermal);
1050                 }
1051         }
1052
1053         switch (model) {
1054         case E1144CS021:
1055                 mode = &repaper_e1144cs021_mode;
1056                 epd->channel_select = repaper_e1144cs021_cs;
1057                 epd->stage_time = 480;
1058                 epd->bytes_per_scan = 96 / 4;
1059                 epd->middle_scan = true; /* data-scan-data */
1060                 epd->pre_border_byte = false;
1061                 epd->border_byte = REPAPER_BORDER_BYTE_ZERO;
1062                 break;
1063
1064         case E1190CS021:
1065                 mode = &repaper_e1190cs021_mode;
1066                 epd->channel_select = repaper_e1190cs021_cs;
1067                 epd->stage_time = 480;
1068                 epd->bytes_per_scan = 128 / 4 / 2;
1069                 epd->middle_scan = false; /* scan-data-scan */
1070                 epd->pre_border_byte = false;
1071                 epd->border_byte = REPAPER_BORDER_BYTE_SET;
1072                 break;
1073
1074         case E2200CS021:
1075                 mode = &repaper_e2200cs021_mode;
1076                 epd->channel_select = repaper_e2200cs021_cs;
1077                 epd->stage_time = 480;
1078                 epd->bytes_per_scan = 96 / 4;
1079                 epd->middle_scan = true; /* data-scan-data */
1080                 epd->pre_border_byte = true;
1081                 epd->border_byte = REPAPER_BORDER_BYTE_NONE;
1082                 break;
1083
1084         case E2271CS021:
1085                 epd->border = devm_gpiod_get(dev, "border", GPIOD_OUT_LOW);
1086                 if (IS_ERR(epd->border)) {
1087                         ret = PTR_ERR(epd->border);
1088                         if (ret != -EPROBE_DEFER)
1089                                 DRM_DEV_ERROR(dev, "Failed to get gpio 'border'\n");
1090                         return ret;
1091                 }
1092
1093                 mode = &repaper_e2271cs021_mode;
1094                 epd->channel_select = repaper_e2271cs021_cs;
1095                 epd->stage_time = 630;
1096                 epd->bytes_per_scan = 176 / 4;
1097                 epd->middle_scan = true; /* data-scan-data */
1098                 epd->pre_border_byte = true;
1099                 epd->border_byte = REPAPER_BORDER_BYTE_NONE;
1100                 break;
1101
1102         default:
1103                 return -ENODEV;
1104         }
1105
1106         epd->mode = mode;
1107         epd->width = mode->hdisplay;
1108         epd->height = mode->vdisplay;
1109         epd->factored_stage_time = epd->stage_time;
1110
1111         line_buffer_size = 2 * epd->width / 8 + epd->bytes_per_scan + 2;
1112         epd->line_buffer = devm_kzalloc(dev, line_buffer_size, GFP_KERNEL);
1113         if (!epd->line_buffer)
1114                 return -ENOMEM;
1115
1116         epd->current_frame = devm_kzalloc(dev, epd->width * epd->height / 8,
1117                                           GFP_KERNEL);
1118         if (!epd->current_frame)
1119                 return -ENOMEM;
1120
1121         drm->mode_config.min_width = mode->hdisplay;
1122         drm->mode_config.max_width = mode->hdisplay;
1123         drm->mode_config.min_height = mode->vdisplay;
1124         drm->mode_config.max_height = mode->vdisplay;
1125
1126         drm_connector_helper_add(&epd->connector, &repaper_connector_hfuncs);
1127         ret = drm_connector_init(drm, &epd->connector, &repaper_connector_funcs,
1128                                  DRM_MODE_CONNECTOR_SPI);
1129         if (ret)
1130                 return ret;
1131
1132         ret = drm_simple_display_pipe_init(drm, &epd->pipe, &repaper_pipe_funcs,
1133                                            repaper_formats, ARRAY_SIZE(repaper_formats),
1134                                            NULL, &epd->connector);
1135         if (ret)
1136                 return ret;
1137
1138         drm_mode_config_reset(drm);
1139
1140         ret = drm_dev_register(drm, 0);
1141         if (ret)
1142                 return ret;
1143
1144         spi_set_drvdata(spi, drm);
1145
1146         DRM_DEBUG_DRIVER("SPI speed: %uMHz\n", spi->max_speed_hz / 1000000);
1147
1148         drm_fbdev_generic_setup(drm, 0);
1149
1150         return 0;
1151 }
1152
1153 static int repaper_remove(struct spi_device *spi)
1154 {
1155         struct drm_device *drm = spi_get_drvdata(spi);
1156
1157         drm_dev_unplug(drm);
1158         drm_atomic_helper_shutdown(drm);
1159
1160         return 0;
1161 }
1162
1163 static void repaper_shutdown(struct spi_device *spi)
1164 {
1165         drm_atomic_helper_shutdown(spi_get_drvdata(spi));
1166 }
1167
1168 static struct spi_driver repaper_spi_driver = {
1169         .driver = {
1170                 .name = "repaper",
1171                 .of_match_table = repaper_of_match,
1172         },
1173         .id_table = repaper_id,
1174         .probe = repaper_probe,
1175         .remove = repaper_remove,
1176         .shutdown = repaper_shutdown,
1177 };
1178 module_spi_driver(repaper_spi_driver);
1179
1180 MODULE_DESCRIPTION("Pervasive Displays RePaper DRM driver");
1181 MODULE_AUTHOR("Noralf Trønnes");
1182 MODULE_LICENSE("GPL");