drivers/mfd/cgbc-core.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Congatec Board Controller core driver.
   4  *
   5  * The x86 Congatec modules have an embedded micro controller named Board
   6  * Controller. This Board Controller has a Watchdog timer, some GPIOs, and two
   7  * I2C busses.
   8  *
   9  * Copyright (C) 2024 Bootlin
  10  *
  11  * Author: Thomas Richard <[email protected]>
  12  */
  13
  14 #include <linux/dmi.h>
  15 #include <linux/iopoll.h>
  16 #include <linux/mfd/cgbc.h>
  17 #include <linux/mfd/core.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/sysfs.h>
  21
  22 #define CGBC_IO_SESSION_BASE    0x0E20
  23 #define CGBC_IO_SESSION_END     0x0E30
  24 #define CGBC_IO_CMD_BASE        0x0E00
  25 #define CGBC_IO_CMD_END         0x0E10
  26
  27 #define CGBC_MASK_STATUS        (BIT(6) | BIT(7))
  28 #define CGBC_MASK_DATA_COUNT    0x1F
  29 #define CGBC_MASK_ERROR_CODE    0x1F
  30
  31 #define CGBC_STATUS_DATA_READY  0x00
  32 #define CGBC_STATUS_CMD_READY   BIT(6)
  33 #define CGBC_STATUS_ERROR       (BIT(6) | BIT(7))
  34
  35 #define CGBC_SESSION_CMD                0x00
  36 #define CGBC_SESSION_CMD_IDLE           0x00
  37 #define CGBC_SESSION_CMD_REQUEST        0x01
  38 #define CGBC_SESSION_DATA               0x01
  39 #define CGBC_SESSION_STATUS             0x02
  40 #define CGBC_SESSION_STATUS_FREE        0x03
  41 #define CGBC_SESSION_ACCESS             0x04
  42 #define CGBC_SESSION_ACCESS_GAINED      0x00
  43
  44 #define CGBC_SESSION_VALID_MIN  0x02
  45 #define CGBC_SESSION_VALID_MAX  0xFE
  46
  47 #define CGBC_CMD_STROBE                 0x00
  48 #define CGBC_CMD_INDEX                  0x02
  49 #define CGBC_CMD_INDEX_CBM_MAN8         0x00
  50 #define CGBC_CMD_INDEX_CBM_AUTO32       0x03
  51 #define CGBC_CMD_DATA                   0x04
  52 #define CGBC_CMD_ACCESS                 0x0C
  53
  54 #define CGBC_CMD_GET_FW_REV     0x21
  55
  56 static struct platform_device *cgbc_pdev;
  57
  58 /* Wait the Board Controller is ready to receive some session commands */
  59 static int cgbc_wait_device(struct cgbc_device_data *cgbc)
  60 {
  61         u16 status;
  62         int ret;
  63
  64         ret = readx_poll_timeout(ioread16, cgbc->io_session + CGBC_SESSION_STATUS, status,
  65                                  status == CGBC_SESSION_STATUS_FREE, 0, 500000);
  66
  67         if (ret || ioread32(cgbc->io_session + CGBC_SESSION_ACCESS))
  68                 ret = -ENODEV;
  69
  70         return ret;
  71 }
  72
  73 static int cgbc_session_command(struct cgbc_device_data *cgbc, u8 cmd)
  74 {
  75         int ret;
  76         u8 val;
  77
  78         ret = readx_poll_timeout(ioread8, cgbc->io_session + CGBC_SESSION_CMD, val,
  79                                  val == CGBC_SESSION_CMD_IDLE, 0, 100000);
  80         if (ret)
  81                 return ret;
  82
  83         iowrite8(cmd, cgbc->io_session + CGBC_SESSION_CMD);
  84
  85         ret = readx_poll_timeout(ioread8, cgbc->io_session + CGBC_SESSION_CMD, val,
  86                                  val == CGBC_SESSION_CMD_IDLE, 0, 100000);
  87         if (ret)
  88                 return ret;
  89
  90         ret = (int)ioread8(cgbc->io_session + CGBC_SESSION_DATA);
  91
  92         iowrite8(CGBC_SESSION_STATUS_FREE, cgbc->io_session + CGBC_SESSION_STATUS);
  93
  94         return ret;
  95 }
  96
  97 static int cgbc_session_request(struct cgbc_device_data *cgbc)
  98 {
  99         unsigned int ret;
 100
 101         ret = cgbc_wait_device(cgbc);
 102
 103         if (ret)
 104                 return dev_err_probe(cgbc->dev, ret, "device not found or not ready\n");
 105
 106         cgbc->session = cgbc_session_command(cgbc, CGBC_SESSION_CMD_REQUEST);
 107
 108         /* The Board Controller sent us a wrong session handle, we cannot communicate with it */
 109         if (cgbc->session < CGBC_SESSION_VALID_MIN || cgbc->session > CGBC_SESSION_VALID_MAX)
 110                 return dev_err_probe(cgbc->dev, -ECONNREFUSED,
 111                                      "failed to get a valid session handle\n");
 112
 113         return 0;
 114 }
 115
 116 static void cgbc_session_release(struct cgbc_device_data *cgbc)
 117 {
 118         if (cgbc_session_command(cgbc, cgbc->session) != cgbc->session)
 119                 dev_warn(cgbc->dev, "failed to release session\n");
 120 }
 121
 122 static bool cgbc_command_lock(struct cgbc_device_data *cgbc)
 123 {
 124         iowrite8(cgbc->session, cgbc->io_cmd + CGBC_CMD_ACCESS);
 125
 126         return ioread8(cgbc->io_cmd + CGBC_CMD_ACCESS) == cgbc->session;
 127 }
 128
 129 static void cgbc_command_unlock(struct cgbc_device_data *cgbc)
 130 {
 131         iowrite8(cgbc->session, cgbc->io_cmd + CGBC_CMD_ACCESS);
 132 }
 133
 134 int cgbc_command(struct cgbc_device_data *cgbc, void *cmd, unsigned int cmd_size, void *data,
 135                  unsigned int data_size, u8 *status)
 136 {
 137         u8 checksum = 0, data_checksum = 0, istatus = 0, val;
 138         u8 *_data = (u8 *)data;
 139         u8 *_cmd = (u8 *)cmd;
 140         int mode_change = -1;
 141         bool lock;
 142         int ret, i;
 143
 144         mutex_lock(&cgbc->lock);
 145
 146         /* Request access */
 147         ret = readx_poll_timeout(cgbc_command_lock, cgbc, lock, lock, 0, 100000);
 148         if (ret)
 149                 goto out;
 150
 151         /* Wait board controller is ready */
 152         ret = readx_poll_timeout(ioread8, cgbc->io_cmd + CGBC_CMD_STROBE, val,
 153                                  val == CGBC_CMD_STROBE, 0, 100000);
 154         if (ret)
 155                 goto release;
 156
 157         /* Write command packet */
 158         if (cmd_size <= 2) {
 159                 iowrite8(CGBC_CMD_INDEX_CBM_MAN8, cgbc->io_cmd + CGBC_CMD_INDEX);
 160         } else {
 161                 iowrite8(CGBC_CMD_INDEX_CBM_AUTO32, cgbc->io_cmd + CGBC_CMD_INDEX);
 162                 if ((cmd_size % 4) != 0x03)
 163                         mode_change = (cmd_size & 0xFFFC) - 1;
 164         }
 165
 166         for (i = 0; i < cmd_size; i++) {
 167                 iowrite8(_cmd[i], cgbc->io_cmd + CGBC_CMD_DATA + (i % 4));
 168                 checksum ^= _cmd[i];
 169                 if (mode_change == i)
 170                         iowrite8((i + 1) | CGBC_CMD_INDEX_CBM_MAN8, cgbc->io_cmd + CGBC_CMD_INDEX);
 171         }
 172
 173         /* Append checksum byte */
 174         iowrite8(checksum, cgbc->io_cmd + CGBC_CMD_DATA + (i % 4));
 175
 176         /* Perform command strobe */
 177         iowrite8(cgbc->session, cgbc->io_cmd + CGBC_CMD_STROBE);
 178
 179         /* Rewind cmd buffer index */
 180         iowrite8(CGBC_CMD_INDEX_CBM_AUTO32, cgbc->io_cmd + CGBC_CMD_INDEX);
 181
 182         /* Wait command completion */
 183         ret = read_poll_timeout(ioread8, val, val == CGBC_CMD_STROBE, 0, 100000, false,
 184                                 cgbc->io_cmd + CGBC_CMD_STROBE);
 185         if (ret)
 186                 goto release;
 187
 188         istatus = ioread8(cgbc->io_cmd + CGBC_CMD_DATA);
 189         checksum = istatus;
 190
 191         /* Check command status */
 192         switch (istatus & CGBC_MASK_STATUS) {
 193         case CGBC_STATUS_DATA_READY:
 194                 if (istatus > data_size)
 195                         istatus = data_size;
 196                 for (i = 0; i < istatus; i++) {
 197                         _data[i] = ioread8(cgbc->io_cmd + CGBC_CMD_DATA + ((i + 1) % 4));
 198                         checksum ^= _data[i];
 199                 }
 200                 data_checksum = ioread8(cgbc->io_cmd + CGBC_CMD_DATA + ((i + 1) % 4));
 201                 istatus &= CGBC_MASK_DATA_COUNT;
 202                 break;
 203         case CGBC_STATUS_ERROR:
 204         case CGBC_STATUS_CMD_READY:
 205                 data_checksum = ioread8(cgbc->io_cmd + CGBC_CMD_DATA + 1);
 206                 if ((istatus & CGBC_MASK_STATUS) == CGBC_STATUS_ERROR)
 207                         ret = -EIO;
 208                 istatus = istatus & CGBC_MASK_ERROR_CODE;
 209                 break;
 210         default:
 211                 data_checksum = ioread8(cgbc->io_cmd + CGBC_CMD_DATA + 1);
 212                 istatus &= CGBC_MASK_ERROR_CODE;
 213                 ret = -EIO;
 214                 break;
 215         }
 216
 217         /* Checksum verification */
 218         if (ret == 0 && data_checksum != checksum)
 219                 ret = -EIO;
 220
 221 release:
 222         cgbc_command_unlock(cgbc);
 223
 224 out:
 225         mutex_unlock(&cgbc->lock);
 226
 227         if (status)
 228                 *status = istatus;
 229
 230         return ret;
 231 }
 232 EXPORT_SYMBOL_GPL(cgbc_command);
 233
 234 static struct mfd_cell cgbc_devs[] = {
 235         { .name = "cgbc-wdt"    },
 236         { .name = "cgbc-gpio"   },
 237         { .name = "cgbc-i2c", .id = 1 },
 238         { .name = "cgbc-i2c", .id = 2 },
 239 };
 240
 241 static int cgbc_map(struct cgbc_device_data *cgbc)
 242 {
 243         struct device *dev = cgbc->dev;
 244         struct platform_device *pdev = to_platform_device(dev);
 245         struct resource *ioport;
 246
 247         ioport = platform_get_resource(pdev, IORESOURCE_IO, 0);
 248         if (!ioport)
 249                 return -EINVAL;
 250
 251         cgbc->io_session = devm_ioport_map(dev, ioport->start, resource_size(ioport));
 252         if (!cgbc->io_session)
 253                 return -ENOMEM;
 254
 255         ioport = platform_get_resource(pdev, IORESOURCE_IO, 1);
 256         if (!ioport)
 257                 return -EINVAL;
 258
 259         cgbc->io_cmd = devm_ioport_map(dev, ioport->start, resource_size(ioport));
 260         if (!cgbc->io_cmd)
 261                 return -ENOMEM;
 262
 263         return 0;
 264 }
 265
 266 static const struct resource cgbc_resources[] = {
 267         {
 268                 .start  = CGBC_IO_SESSION_BASE,
 269                 .end    = CGBC_IO_SESSION_END,
 270                 .flags  = IORESOURCE_IO,
 271         },
 272         {
 273                 .start  = CGBC_IO_CMD_BASE,
 274                 .end    = CGBC_IO_CMD_END,
 275                 .flags  = IORESOURCE_IO,
 276         },
 277 };
 278
 279 static ssize_t cgbc_version_show(struct device *dev,
 280                                  struct device_attribute *attr, char *buf)
 281 {
 282         struct cgbc_device_data *cgbc = dev_get_drvdata(dev);
 283
 284         return sysfs_emit(buf, "CGBCP%c%c%c\n", cgbc->version.feature, cgbc->version.major,
 285                           cgbc->version.minor);
 286 }
 287
 288 static DEVICE_ATTR_RO(cgbc_version);
 289
 290 static struct attribute *cgbc_attrs[] = {
 291         &dev_attr_cgbc_version.attr,
 292         NULL
 293 };
 294
 295 ATTRIBUTE_GROUPS(cgbc);
 296
 297 static int cgbc_get_version(struct cgbc_device_data *cgbc)
 298 {
 299         u8 cmd = CGBC_CMD_GET_FW_REV;
 300         u8 data[4];
 301         int ret;
 302
 303         ret = cgbc_command(cgbc, &cmd, 1, &data, sizeof(data), NULL);
 304         if (ret)
 305                 return ret;
 306
 307         cgbc->version.feature = data[0];
 308         cgbc->version.major = data[1];
 309         cgbc->version.minor = data[2];
 310
 311         return 0;
 312 }
 313
 314 static int cgbc_init_device(struct cgbc_device_data *cgbc)
 315 {
 316         int ret;
 317
 318         ret = cgbc_session_request(cgbc);
 319         if (ret)
 320                 return ret;
 321
 322         ret = cgbc_get_version(cgbc);
 323         if (ret)
 324                 goto release_session;
 325
 326         ret = mfd_add_devices(cgbc->dev, -1, cgbc_devs, ARRAY_SIZE(cgbc_devs),
 327                               NULL, 0, NULL);
 328         if (ret)
 329                 goto release_session;
 330
 331         return 0;
 332
 333 release_session:
 334         cgbc_session_release(cgbc);
 335         return ret;
 336 }
 337
 338 static int cgbc_probe(struct platform_device *pdev)
 339 {
 340         struct device *dev = &pdev->dev;
 341         struct cgbc_device_data *cgbc;
 342         int ret;
 343
 344         cgbc = devm_kzalloc(dev, sizeof(*cgbc), GFP_KERNEL);
 345         if (!cgbc)
 346                 return -ENOMEM;
 347
 348         cgbc->dev = dev;
 349
 350         ret = cgbc_map(cgbc);
 351         if (ret)
 352                 return ret;
 353
 354         mutex_init(&cgbc->lock);
 355
 356         platform_set_drvdata(pdev, cgbc);
 357
 358         return cgbc_init_device(cgbc);
 359 }
 360
 361 static void cgbc_remove(struct platform_device *pdev)
 362 {
 363         struct cgbc_device_data *cgbc = platform_get_drvdata(pdev);
 364
 365         cgbc_session_release(cgbc);
 366
 367         mfd_remove_devices(&pdev->dev);
 368 }
 369
 370 static struct platform_driver cgbc_driver = {
 371         .driver         = {
 372                 .name           = "cgbc",
 373                 .dev_groups     = cgbc_groups,
 374         },
 375         .probe          = cgbc_probe,
 376         .remove         = cgbc_remove,
 377 };
 378
 379 static const struct dmi_system_id cgbc_dmi_table[] __initconst = {
 380         {
 381                 .ident = "SA7",
 382                 .matches = {
 383                         DMI_MATCH(DMI_BOARD_VENDOR, "congatec"),
 384                         DMI_MATCH(DMI_BOARD_NAME, "conga-SA7"),
 385                 },
 386         },
 387         {}
 388 };
 389 MODULE_DEVICE_TABLE(dmi, cgbc_dmi_table);
 390
 391 static int __init cgbc_init(void)
 392 {
 393         const struct dmi_system_id *id;
 394         int ret = -ENODEV;
 395
 396         id = dmi_first_match(cgbc_dmi_table);
 397         if (IS_ERR_OR_NULL(id))
 398                 return ret;
 399
 400         cgbc_pdev = platform_device_register_simple("cgbc", PLATFORM_DEVID_NONE, cgbc_resources,
 401                                                     ARRAY_SIZE(cgbc_resources));
 402         if (IS_ERR(cgbc_pdev))
 403                 return PTR_ERR(cgbc_pdev);
 404
 405         return platform_driver_register(&cgbc_driver);
 406 }
 407
 408 static void __exit cgbc_exit(void)
 409 {
 410         platform_device_unregister(cgbc_pdev);
 411         platform_driver_unregister(&cgbc_driver);
 412 }
 413
 414 module_init(cgbc_init);
 415 module_exit(cgbc_exit);
 416
 417 MODULE_DESCRIPTION("Congatec Board Controller Core Driver");
 418 MODULE_AUTHOR("Thomas Richard <[email protected]>");
 419 MODULE_LICENSE("GPL");
 420 MODULE_ALIAS("platform:cgbc-core");