drivers/tty/goldfish.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Google, Inc.
   4  * Copyright (C) 2012 Intel, Inc.
   5  * Copyright (C) 2017 Imagination Technologies Ltd.
   6  */
   7
   8 #include <linux/console.h>
   9 #include <linux/interrupt.h>
  10 #include <linux/platform_device.h>
  11 #include <linux/tty.h>
  12 #include <linux/tty_flip.h>
  13 #include <linux/slab.h>
  14 #include <linux/io.h>
  15 #include <linux/module.h>
  16 #include <linux/mod_devicetable.h>
  17 #include <linux/goldfish.h>
  18 #include <linux/mm.h>
  19 #include <linux/dma-mapping.h>
  20 #include <linux/serial_core.h>
  21
  22 /* Goldfish tty register's offsets */
  23 #define GOLDFISH_TTY_REG_BYTES_READY    0x04
  24 #define GOLDFISH_TTY_REG_CMD            0x08
  25 #define GOLDFISH_TTY_REG_DATA_PTR       0x10
  26 #define GOLDFISH_TTY_REG_DATA_LEN       0x14
  27 #define GOLDFISH_TTY_REG_DATA_PTR_HIGH  0x18
  28 #define GOLDFISH_TTY_REG_VERSION        0x20
  29
  30 /* Goldfish tty commands */
  31 #define GOLDFISH_TTY_CMD_INT_DISABLE    0
  32 #define GOLDFISH_TTY_CMD_INT_ENABLE     1
  33 #define GOLDFISH_TTY_CMD_WRITE_BUFFER   2
  34 #define GOLDFISH_TTY_CMD_READ_BUFFER    3
  35
  36 struct goldfish_tty {
  37         struct tty_port port;
  38         spinlock_t lock;
  39         void __iomem *base;
  40         u32 irq;
  41         int opencount;
  42         struct console console;
  43         u32 version;
  44         struct device *dev;
  45 };
  46
  47 static DEFINE_MUTEX(goldfish_tty_lock);
  48 static struct tty_driver *goldfish_tty_driver;
  49 static u32 goldfish_tty_line_count = 8;
  50 static u32 goldfish_tty_current_line_count;
  51 static struct goldfish_tty *goldfish_ttys;
  52
  53 static void do_rw_io(struct goldfish_tty *qtty, unsigned long address,
  54                      size_t count, bool is_write)
  55 {
  56         unsigned long irq_flags;
  57         void __iomem *base = qtty->base;
  58
  59         spin_lock_irqsave(&qtty->lock, irq_flags);
  60         gf_write_ptr((void *)address, base + GOLDFISH_TTY_REG_DATA_PTR,
  61                      base + GOLDFISH_TTY_REG_DATA_PTR_HIGH);
  62         gf_iowrite32(count, base + GOLDFISH_TTY_REG_DATA_LEN);
  63
  64         if (is_write)
  65                 gf_iowrite32(GOLDFISH_TTY_CMD_WRITE_BUFFER,
  66                        base + GOLDFISH_TTY_REG_CMD);
  67         else
  68                 gf_iowrite32(GOLDFISH_TTY_CMD_READ_BUFFER,
  69                        base + GOLDFISH_TTY_REG_CMD);
  70
  71         spin_unlock_irqrestore(&qtty->lock, irq_flags);
  72 }
  73
  74 static void goldfish_tty_rw(struct goldfish_tty *qtty, unsigned long addr,
  75                             size_t count, bool is_write)
  76 {
  77         dma_addr_t dma_handle;
  78         enum dma_data_direction dma_dir;
  79
  80         dma_dir = (is_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
  81         if (qtty->version > 0) {
  82                 /*
  83                  * Goldfish TTY for Ranchu platform uses
  84                  * physical addresses and DMA for read/write operations
  85                  */
  86                 unsigned long addr_end = addr + count;
  87
  88                 while (addr < addr_end) {
  89                         unsigned long pg_end = (addr & PAGE_MASK) + PAGE_SIZE;
  90                         unsigned long next =
  91                                         pg_end < addr_end ? pg_end : addr_end;
  92                         unsigned long avail = next - addr;
  93
  94                         /*
  95                          * Map the buffer's virtual address to the DMA address
  96                          * so the buffer can be accessed by the device.
  97                          */
  98                         dma_handle = dma_map_single(qtty->dev, (void *)addr,
  99                                                     avail, dma_dir);
 100
 101                         if (dma_mapping_error(qtty->dev, dma_handle)) {
 102                                 dev_err(qtty->dev, "tty: DMA mapping error.\n");
 103                                 return;
 104                         }
 105                         do_rw_io(qtty, dma_handle, avail, is_write);
 106
 107                         /*
 108                          * Unmap the previously mapped region after
 109                          * the completion of the read/write operation.
 110                          */
 111                         dma_unmap_single(qtty->dev, dma_handle, avail, dma_dir);
 112
 113                         addr += avail;
 114                 }
 115         } else {
 116                 /*
 117                  * Old style Goldfish TTY used on the Goldfish platform
 118                  * uses virtual addresses.
 119                  */
 120                 do_rw_io(qtty, addr, count, is_write);
 121         }
 122 }
 123
 124 static void goldfish_tty_do_write(int line, const u8 *buf, size_t count)
 125 {
 126         struct goldfish_tty *qtty = &goldfish_ttys[line];
 127
 128         goldfish_tty_rw(qtty, (unsigned long)buf, count, true);
 129 }
 130
 131 static irqreturn_t goldfish_tty_interrupt(int irq, void *dev_id)
 132 {
 133         struct goldfish_tty *qtty = dev_id;
 134         void __iomem *base = qtty->base;
 135         u8 *buf;
 136         u32 count;
 137
 138         count = gf_ioread32(base + GOLDFISH_TTY_REG_BYTES_READY);
 139         if (count == 0)
 140                 return IRQ_NONE;
 141
 142         count = tty_prepare_flip_string(&qtty->port, &buf, count);
 143
 144         goldfish_tty_rw(qtty, (unsigned long)buf, count, false);
 145
 146         tty_flip_buffer_push(&qtty->port);
 147         return IRQ_HANDLED;
 148 }
 149
 150 static int goldfish_tty_activate(struct tty_port *port, struct tty_struct *tty)
 151 {
 152         struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
 153                                                                         port);
 154         gf_iowrite32(GOLDFISH_TTY_CMD_INT_ENABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
 155         return 0;
 156 }
 157
 158 static void goldfish_tty_shutdown(struct tty_port *port)
 159 {
 160         struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
 161                                                                         port);
 162         gf_iowrite32(GOLDFISH_TTY_CMD_INT_DISABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
 163 }
 164
 165 static int goldfish_tty_open(struct tty_struct *tty, struct file *filp)
 166 {
 167         struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
 168         return tty_port_open(&qtty->port, tty, filp);
 169 }
 170
 171 static void goldfish_tty_close(struct tty_struct *tty, struct file *filp)
 172 {
 173         tty_port_close(tty->port, tty, filp);
 174 }
 175
 176 static void goldfish_tty_hangup(struct tty_struct *tty)
 177 {
 178         tty_port_hangup(tty->port);
 179 }
 180
 181 static ssize_t goldfish_tty_write(struct tty_struct *tty, const u8 *buf,
 182                                   size_t count)
 183 {
 184         goldfish_tty_do_write(tty->index, buf, count);
 185         return count;
 186 }
 187
 188 static unsigned int goldfish_tty_write_room(struct tty_struct *tty)
 189 {
 190         return 0x10000;
 191 }
 192
 193 static unsigned int goldfish_tty_chars_in_buffer(struct tty_struct *tty)
 194 {
 195         struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
 196         void __iomem *base = qtty->base;
 197         return gf_ioread32(base + GOLDFISH_TTY_REG_BYTES_READY);
 198 }
 199
 200 static void goldfish_tty_console_write(struct console *co, const char *b,
 201                                                                 unsigned count)
 202 {
 203         goldfish_tty_do_write(co->index, b, count);
 204 }
 205
 206 static struct tty_driver *goldfish_tty_console_device(struct console *c,
 207                                                                 int *index)
 208 {
 209         *index = c->index;
 210         return goldfish_tty_driver;
 211 }
 212
 213 static int goldfish_tty_console_setup(struct console *co, char *options)
 214 {
 215         if ((unsigned)co->index >= goldfish_tty_line_count)
 216                 return -ENODEV;
 217         if (!goldfish_ttys[co->index].base)
 218                 return -ENODEV;
 219         return 0;
 220 }
 221
 222 static const struct tty_port_operations goldfish_port_ops = {
 223         .activate = goldfish_tty_activate,
 224         .shutdown = goldfish_tty_shutdown
 225 };
 226
 227 static const struct tty_operations goldfish_tty_ops = {
 228         .open = goldfish_tty_open,
 229         .close = goldfish_tty_close,
 230         .hangup = goldfish_tty_hangup,
 231         .write = goldfish_tty_write,
 232         .write_room = goldfish_tty_write_room,
 233         .chars_in_buffer = goldfish_tty_chars_in_buffer,
 234 };
 235
 236 static int goldfish_tty_create_driver(void)
 237 {
 238         int ret;
 239         struct tty_driver *tty;
 240
 241         goldfish_ttys = kcalloc(goldfish_tty_line_count,
 242                                 sizeof(*goldfish_ttys),
 243                                 GFP_KERNEL);
 244         if (goldfish_ttys == NULL) {
 245                 ret = -ENOMEM;
 246                 goto err_alloc_goldfish_ttys_failed;
 247         }
 248         tty = tty_alloc_driver(goldfish_tty_line_count,
 249                         TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
 250                         TTY_DRIVER_DYNAMIC_DEV);
 251         if (IS_ERR(tty)) {
 252                 ret = PTR_ERR(tty);
 253                 goto err_tty_alloc_driver_failed;
 254         }
 255         tty->driver_name = "goldfish";
 256         tty->name = "ttyGF";
 257         tty->type = TTY_DRIVER_TYPE_SERIAL;
 258         tty->subtype = SERIAL_TYPE_NORMAL;
 259         tty->init_termios = tty_std_termios;
 260         tty_set_operations(tty, &goldfish_tty_ops);
 261         ret = tty_register_driver(tty);
 262         if (ret)
 263                 goto err_tty_register_driver_failed;
 264
 265         goldfish_tty_driver = tty;
 266         return 0;
 267
 268 err_tty_register_driver_failed:
 269         tty_driver_kref_put(tty);
 270 err_tty_alloc_driver_failed:
 271         kfree(goldfish_ttys);
 272         goldfish_ttys = NULL;
 273 err_alloc_goldfish_ttys_failed:
 274         return ret;
 275 }
 276
 277 static void goldfish_tty_delete_driver(void)
 278 {
 279         tty_unregister_driver(goldfish_tty_driver);
 280         tty_driver_kref_put(goldfish_tty_driver);
 281         goldfish_tty_driver = NULL;
 282         kfree(goldfish_ttys);
 283         goldfish_ttys = NULL;
 284 }
 285
 286 static int goldfish_tty_probe(struct platform_device *pdev)
 287 {
 288         struct goldfish_tty *qtty;
 289         int ret = -ENODEV;
 290         struct resource *r;
 291         struct device *ttydev;
 292         void __iomem *base;
 293         int irq;
 294         unsigned int line;
 295
 296         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 297         if (!r) {
 298                 pr_err("goldfish_tty: No MEM resource available!\n");
 299                 return -ENOMEM;
 300         }
 301
 302         base = ioremap(r->start, 0x1000);
 303         if (!base) {
 304                 pr_err("goldfish_tty: Unable to ioremap base!\n");
 305                 return -ENOMEM;
 306         }
 307
 308         irq = platform_get_irq(pdev, 0);
 309         if (irq < 0) {
 310                 ret = irq;
 311                 goto err_unmap;
 312         }
 313
 314         mutex_lock(&goldfish_tty_lock);
 315
 316         if (pdev->id == PLATFORM_DEVID_NONE)
 317                 line = goldfish_tty_current_line_count;
 318         else
 319                 line = pdev->id;
 320
 321         if (line >= goldfish_tty_line_count) {
 322                 pr_err("goldfish_tty: Reached maximum tty number of %d.\n",
 323                        goldfish_tty_current_line_count);
 324                 ret = -ENOMEM;
 325                 goto err_unlock;
 326         }
 327
 328         if (goldfish_tty_current_line_count == 0) {
 329                 ret = goldfish_tty_create_driver();
 330                 if (ret)
 331                         goto err_unlock;
 332         }
 333         goldfish_tty_current_line_count++;
 334
 335         qtty = &goldfish_ttys[line];
 336         spin_lock_init(&qtty->lock);
 337         tty_port_init(&qtty->port);
 338         qtty->port.ops = &goldfish_port_ops;
 339         qtty->base = base;
 340         qtty->irq = irq;
 341         qtty->dev = &pdev->dev;
 342
 343         /*
 344          * Goldfish TTY device used by the Goldfish emulator
 345          * should identify itself with 0, forcing the driver
 346          * to use virtual addresses. Goldfish TTY device
 347          * on Ranchu emulator (qemu2) returns 1 here and
 348          * driver will use physical addresses.
 349          */
 350         qtty->version = gf_ioread32(base + GOLDFISH_TTY_REG_VERSION);
 351
 352         /*
 353          * Goldfish TTY device on Ranchu emulator (qemu2)
 354          * will use DMA for read/write IO operations.
 355          */
 356         if (qtty->version > 0) {
 357                 /*
 358                  * Initialize dma_mask to 32-bits.
 359                  */
 360                 if (!pdev->dev.dma_mask)
 361                         pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
 362                 ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
 363                 if (ret) {
 364                         dev_err(&pdev->dev, "No suitable DMA available.\n");
 365                         goto err_dec_line_count;
 366                 }
 367         }
 368
 369         gf_iowrite32(GOLDFISH_TTY_CMD_INT_DISABLE, base + GOLDFISH_TTY_REG_CMD);
 370
 371         ret = request_irq(irq, goldfish_tty_interrupt, IRQF_SHARED,
 372                           "goldfish_tty", qtty);
 373         if (ret) {
 374                 pr_err("goldfish_tty: No IRQ available!\n");
 375                 goto err_dec_line_count;
 376         }
 377
 378         ttydev = tty_port_register_device(&qtty->port, goldfish_tty_driver,
 379                                           line, &pdev->dev);
 380         if (IS_ERR(ttydev)) {
 381                 ret = PTR_ERR(ttydev);
 382                 goto err_tty_register_device_failed;
 383         }
 384
 385         strcpy(qtty->console.name, "ttyGF");
 386         qtty->console.write = goldfish_tty_console_write;
 387         qtty->console.device = goldfish_tty_console_device;
 388         qtty->console.setup = goldfish_tty_console_setup;
 389         qtty->console.flags = CON_PRINTBUFFER;
 390         qtty->console.index = line;
 391         register_console(&qtty->console);
 392         platform_set_drvdata(pdev, qtty);
 393
 394         mutex_unlock(&goldfish_tty_lock);
 395         return 0;
 396
 397 err_tty_register_device_failed:
 398         free_irq(irq, qtty);
 399 err_dec_line_count:
 400         tty_port_destroy(&qtty->port);
 401         goldfish_tty_current_line_count--;
 402         if (goldfish_tty_current_line_count == 0)
 403                 goldfish_tty_delete_driver();
 404 err_unlock:
 405         mutex_unlock(&goldfish_tty_lock);
 406 err_unmap:
 407         iounmap(base);
 408         return ret;
 409 }
 410
 411 static int goldfish_tty_remove(struct platform_device *pdev)
 412 {
 413         struct goldfish_tty *qtty = platform_get_drvdata(pdev);
 414
 415         mutex_lock(&goldfish_tty_lock);
 416
 417         unregister_console(&qtty->console);
 418         tty_unregister_device(goldfish_tty_driver, qtty->console.index);
 419         iounmap(qtty->base);
 420         qtty->base = NULL;
 421         free_irq(qtty->irq, qtty);
 422         tty_port_destroy(&qtty->port);
 423         goldfish_tty_current_line_count--;
 424         if (goldfish_tty_current_line_count == 0)
 425                 goldfish_tty_delete_driver();
 426         mutex_unlock(&goldfish_tty_lock);
 427         return 0;
 428 }
 429
 430 #ifdef CONFIG_GOLDFISH_TTY_EARLY_CONSOLE
 431 static void gf_early_console_putchar(struct uart_port *port, unsigned char ch)
 432 {
 433         gf_iowrite32(ch, port->membase);
 434 }
 435
 436 static void gf_early_write(struct console *con, const char *s, unsigned int n)
 437 {
 438         struct earlycon_device *dev = con->data;
 439
 440         uart_console_write(&dev->port, s, n, gf_early_console_putchar);
 441 }
 442
 443 static int __init gf_earlycon_setup(struct earlycon_device *device,
 444                                     const char *opt)
 445 {
 446         if (!device->port.membase)
 447                 return -ENODEV;
 448
 449         device->con->write = gf_early_write;
 450         return 0;
 451 }
 452
 453 OF_EARLYCON_DECLARE(early_gf_tty, "google,goldfish-tty", gf_earlycon_setup);
 454 #endif
 455
 456 static const struct of_device_id goldfish_tty_of_match[] = {
 457         { .compatible = "google,goldfish-tty", },
 458         {},
 459 };
 460
 461 MODULE_DEVICE_TABLE(of, goldfish_tty_of_match);
 462
 463 static struct platform_driver goldfish_tty_platform_driver = {
 464         .probe = goldfish_tty_probe,
 465         .remove = goldfish_tty_remove,
 466         .driver = {
 467                 .name = "goldfish_tty",
 468                 .of_match_table = goldfish_tty_of_match,
 469         }
 470 };
 471
 472 module_platform_driver(goldfish_tty_platform_driver);
 473
 474 MODULE_LICENSE("GPL v2");