utils/ucmb/driver/ucmb.c

   1 /*
   2  * Microcontroller Message Bus
   3  *
   4  * Copyright (c) 2009 Michael Buesch <mb@bu3sch.de>
   5  *
   6  * Licensed under the GNU/GPL. See COPYING for details.
   7  */
   8
   9 #include "ucmb.h"
  10
  11 #include <linux/module.h>
  12 #include <linux/platform_device.h>
  13 #include <linux/miscdevice.h>
  14 #include <linux/fs.h>
  15 #include <linux/spi/spi.h>
  16 #include <linux/spi/spi_gpio.h>
  17 #include <linux/spi/spi_bitbang.h>
  18 #include <linux/gfp.h>
  19 #include <linux/delay.h>
  20 #include <linux/crc16.h>
  21
  22
  23 #define PFX     "ucmb: "
  24
  25 #define DEBUG
  26
  27
  28 MODULE_LICENSE("GPL");
  29 MODULE_DESCRIPTION("Microcontroller Message Bus");
  30 MODULE_AUTHOR("Michael Buesch");
  31
  32
  33 struct ucmb {
  34         unsigned int msg_delay_ms;
  35
  36         /* Misc character device driver */
  37         struct miscdevice mdev;
  38         struct file_operations mdev_fops;
  39
  40         /* SPI driver */
  41         struct spi_device *sdev;
  42
  43         /* SPI-GPIO driver */
  44         struct spi_gpio_platform_data spi_gpio_pdata;
  45         struct platform_device spi_gpio_pdev;
  46 };
  47
  48 struct ucmb_message_hdr {
  49         __le16 magic;           /* UCMB_MAGIC */
  50         __le16 len;             /* Payload length (excluding header) */
  51 } __attribute__((packed));
  52
  53 struct ucmb_message_footer {
  54         __le16 crc;             /* CRC of the header + payload. */
  55 } __attribute__((packed));
  56
  57 struct ucmb_status {
  58         __le16 magic;           /* UCMB_MAGIC */
  59         __le16 code;            /* enum ucmb_status_code */
  60 } __attribute__((packed));
  61
  62 #define UCMB_MAGIC              0x1337
  63 #define UCMB_MAX_MSG_LEN        0x200
  64
  65 enum ucmb_status_code {
  66         UCMB_STAT_OK = 0,
  67         UCMB_STAT_EPROTO,       /* Protocol format error */
  68         UCMB_STAT_ENOMEM,       /* Out of memory */
  69         UCMB_STAT_E2BIG,        /* Message too big */
  70         UCMB_STAT_ECRC,         /* CRC error */
  71 };
  72
  73
  74 static int ucmb_spi_busnum_count = 1337;
  75
  76
  77 static struct ucmb_platform_data ucmb_list[] = {
  78         { //FIXME don't define it here.
  79                 .name           = "ucmb",
  80                 .gpio_cs        = 3,
  81                 .gpio_sck       = 0,
  82                 .gpio_miso      = 1,
  83                 .gpio_mosi      = 2,
  84                 .mode           = SPI_MODE_0,
  85                 .max_speed_hz   = 128000, /* Hz */
  86                 .msg_delay_ms   = 1, /* mS */
  87         },
  88 };
  89
  90
  91 static int __devinit ucmb_spi_probe(struct spi_device *sdev)
  92 {
  93         return 0;
  94 }
  95
  96 static int __devexit ucmb_spi_remove(struct spi_device *sdev)
  97 {
  98         return 0;
  99 }
 100
 101 static struct spi_driver ucmb_spi_driver = {
 102         .driver         = {
 103                 .name   = "ucmb",
 104                 .bus    = &spi_bus_type,
 105                 .owner  = THIS_MODULE,
 106         },
 107         .probe          = ucmb_spi_probe,
 108         .remove         = __devexit_p(ucmb_spi_remove),
 109 };
 110
 111 static int ucmb_status_code_to_errno(enum ucmb_status_code code)
 112 {
 113         switch (code) {
 114         case UCMB_STAT_OK:
 115                 return 0;
 116         case UCMB_STAT_EPROTO:
 117                 return -EPROTO;
 118         case UCMB_STAT_ENOMEM:
 119                 return -ENOMEM;
 120         case UCMB_STAT_E2BIG:
 121                 return -E2BIG;
 122         case UCMB_STAT_ECRC:
 123                 return -EBADMSG;
 124         }
 125         return -EBUSY;
 126 }
 127
 128 static inline struct ucmb * filp_to_ucmb(struct file *filp)
 129 {
 130         return container_of(filp->f_op, struct ucmb, mdev_fops);
 131 }
 132
 133 static ssize_t ucmb_read(struct file *filp, char __user *user_buf,
 134                          size_t size, loff_t *offp)
 135 {
 136         struct ucmb *ucmb = filp_to_ucmb(filp);
 137         u8 *buf;
 138         int res, err;
 139         struct ucmb_message_hdr hdr;
 140         struct ucmb_message_footer footer;
 141         struct ucmb_status status = { .magic = cpu_to_le16(UCMB_MAGIC), };
 142         u16 crc = 0xFFFF;
 143
 144         size = min_t(size_t, size, PAGE_SIZE);
 145
 146         err = -ENOMEM;
 147         buf = (char *)__get_free_page(GFP_KERNEL);
 148         if (!buf)
 149                 goto out;
 150
 151         err = spi_read(ucmb->sdev, (u8 *)&hdr, sizeof(hdr));
 152         if (err)
 153                 goto out_free;
 154 #ifdef DEBUG
 155         printk(KERN_DEBUG PFX "Received message header 0x%04X 0x%04X\n",
 156                le16_to_cpu(hdr.magic), le16_to_cpu(hdr.len));
 157 #endif
 158         err = -EPROTO;
 159         if (hdr.magic != cpu_to_le16(UCMB_MAGIC))
 160                 goto out_free;
 161         err = -ENOBUFS;
 162         if (size < le16_to_cpu(hdr.len))
 163                 goto out_free;
 164         size = le16_to_cpu(hdr.len);
 165         err = spi_read(ucmb->sdev, buf, size);
 166         if (err)
 167                 goto out_free;
 168         err = spi_read(ucmb->sdev, (u8 *)&footer, sizeof(footer));
 169         if (err)
 170                 goto out_free;
 171
 172         crc = crc16(crc, &hdr, sizeof(hdr));
 173         crc = crc16(crc, buf, size);
 174         crc ^= 0xFFFF;
 175         if (crc != le16_to_cpu(footer.crc)) {
 176                 err = -EPROTO;
 177                 status.code = UCMB_STAT_ECRC;
 178                 goto out_send_status;
 179         }
 180
 181         if (copy_to_user(user_buf, buf, size)) {
 182                 err = -EFAULT;
 183                 status.code = UCMB_STAT_ENOMEM;
 184                 goto out_send_status;
 185         }
 186
 187         status.code = UCMB_STAT_OK;
 188         err = 0;
 189
 190 out_send_status:
 191         res = spi_write(ucmb->sdev, (u8 *)&status, sizeof(status));
 192         if (res && !err)
 193                 err = res;
 194 out_free:
 195         free_page((unsigned long)buf);
 196 out:
 197         return err ? err : size;
 198 }
 199
 200 static ssize_t ucmb_write(struct file *filp, const char __user *user_buf,
 201                           size_t size, loff_t *offp)
 202 {
 203         struct ucmb *ucmb = filp_to_ucmb(filp);
 204         u8 *buf;
 205         int err;
 206         struct ucmb_message_hdr hdr = { .magic = cpu_to_le16(UCMB_MAGIC), };
 207         struct ucmb_message_footer footer = { .crc = 0xFFFF, };
 208         struct ucmb_status status;
 209         struct spi_transfer spi_hdr_xfer;
 210         struct spi_transfer spi_footer_xfer;
 211         struct spi_transfer spi_data_xfer;
 212         struct spi_message spi_msg;
 213
 214         err = -ENOMEM;
 215         buf = (char *)__get_free_page(GFP_KERNEL);
 216         if (!buf)
 217                 goto out;
 218
 219         size = min_t(size_t, PAGE_SIZE, size);
 220         size = min_t(size_t, UCMB_MAX_MSG_LEN, size);
 221         err = -EFAULT;
 222         if (copy_from_user(buf, user_buf, size))
 223                 goto out_free;
 224         hdr.len = cpu_to_le16(size);
 225
 226         footer.crc = crc16(footer.crc, &hdr, sizeof(hdr));
 227         footer.crc = crc16(footer.crc, buf, size);
 228         footer.crc ^= 0xFFFF;
 229
 230         spi_message_init(&spi_msg);
 231
 232         memset(&spi_hdr_xfer, 0, sizeof(spi_hdr_xfer));
 233         spi_hdr_xfer.tx_buf = &hdr;
 234         spi_hdr_xfer.len = sizeof(hdr);
 235         spi_message_add_tail(&spi_hdr_xfer, &spi_msg);
 236
 237         memset(&spi_data_xfer, 0, sizeof(spi_data_xfer));
 238         spi_data_xfer.tx_buf = buf;
 239         spi_data_xfer.len = size;
 240         spi_message_add_tail(&spi_data_xfer, &spi_msg);
 241
 242         memset(&spi_footer_xfer, 0, sizeof(spi_footer_xfer));
 243         spi_footer_xfer.tx_buf = &footer;
 244         spi_footer_xfer.len = sizeof(footer);
 245         spi_message_add_tail(&spi_footer_xfer, &spi_msg);
 246
 247         /* Send the message, including header. */
 248         err = spi_sync(ucmb->sdev, &spi_msg);
 249         if (err)
 250                 goto out_free;
 251
 252         /* The microcontroller deserves some time to process the message. */
 253         if (ucmb->msg_delay_ms)
 254                 msleep(ucmb->msg_delay_ms);
 255
 256         /* Get the status code. */
 257         err = spi_read(ucmb->sdev, (u8 *)&status, sizeof(status));
 258         if (err)
 259                 goto out_free;
 260 #ifdef DEBUG
 261         printk(KERN_DEBUG PFX "Sent message. Status report: 0x%04X 0x%04X\n",
 262                le16_to_cpu(status.magic), le16_to_cpu(status.code));
 263 #endif
 264         err = -EPROTO;
 265         if (status.magic != cpu_to_le16(UCMB_MAGIC))
 266                 goto out_free;
 267         err = ucmb_status_code_to_errno(le16_to_cpu(status.code));
 268         if (err)
 269                 goto out_free;
 270
 271 out_free:
 272         free_page((unsigned long)buf);
 273 out:
 274         return err ? err : size;
 275 }
 276
 277 static int __devinit ucmb_probe(struct platform_device *pdev)
 278 {
 279         struct ucmb_platform_data *pdata;
 280         struct ucmb *ucmb;
 281         int err;
 282         const int bus_num = ucmb_spi_busnum_count++;
 283         struct spi_bitbang *bb;
 284
 285         pdata = pdev->dev.platform_data;
 286         if (!pdata)
 287                 return -ENXIO;
 288
 289         ucmb = kzalloc(sizeof(struct ucmb), GFP_KERNEL);
 290         if (!ucmb)
 291                 return -ENOMEM;
 292         ucmb->msg_delay_ms = pdata->msg_delay_ms;
 293
 294         /* Create the SPI GPIO bus master. */
 295
 296 #ifdef CONFIG_SPI_GPIO_MODULE
 297         err = request_module("spi_gpio");
 298         if (err)
 299                 printk(KERN_WARNING PFX "Failed to request spi_gpio module\n");
 300 #endif /* CONFIG_SPI_GPIO_MODULE */
 301
 302         ucmb->spi_gpio_pdata.sck = pdata->gpio_sck;
 303         ucmb->spi_gpio_pdata.mosi = pdata->gpio_mosi;
 304         ucmb->spi_gpio_pdata.miso = pdata->gpio_miso;
 305         ucmb->spi_gpio_pdata.num_chipselect = 1;
 306
 307         ucmb->spi_gpio_pdev.name = "spi_gpio";
 308         ucmb->spi_gpio_pdev.id = bus_num;
 309         ucmb->spi_gpio_pdev.dev.platform_data = &ucmb->spi_gpio_pdata;
 310
 311         err = platform_device_register(&ucmb->spi_gpio_pdev);
 312         if (err) {
 313                 printk(KERN_ERR PFX "Failed to register SPI-GPIO platform device\n");
 314                 goto err_free_ucmb;
 315         }
 316         bb = platform_get_drvdata(&ucmb->spi_gpio_pdev);
 317         if (!bb || !bb->master) {
 318                 printk(KERN_ERR PFX "No bitbanged master device found.\n");
 319                 goto err_unreg_spi_gpio_pdev;
 320         }
 321
 322         /* Create the SPI device. */
 323
 324         ucmb->sdev = spi_alloc_device(bb->master);
 325         if (!ucmb->sdev) {
 326                 printk(KERN_ERR PFX "Failed to allocate SPI device\n");
 327                 goto err_unreg_spi_gpio_pdev;
 328         }
 329         ucmb->sdev->max_speed_hz = pdata->max_speed_hz;
 330         ucmb->sdev->chip_select = 0;
 331         ucmb->sdev->mode = pdata->mode;
 332         strlcpy(ucmb->sdev->modalias, "ucmb", /* We are the SPI driver. */
 333                 sizeof(ucmb->sdev->modalias));
 334         ucmb->sdev->controller_data = (void *)pdata->gpio_cs;
 335         err = spi_add_device(ucmb->sdev);
 336         if (err) {
 337                 printk(KERN_ERR PFX "Failed to add SPI device\n");
 338                 goto err_free_spi_device;
 339         }
 340
 341         /* Create the Misc char device. */
 342
 343         ucmb->mdev.minor = MISC_DYNAMIC_MINOR;
 344         ucmb->mdev.name = pdata->name;
 345         ucmb->mdev.parent = &pdev->dev;
 346         ucmb->mdev_fops.read = ucmb_read;
 347         ucmb->mdev_fops.write = ucmb_write;
 348         ucmb->mdev.fops = &ucmb->mdev_fops;
 349
 350         err = misc_register(&ucmb->mdev);
 351         if (err) {
 352                 printk(KERN_ERR PFX "Failed to register miscdev %s\n",
 353                        ucmb->mdev.name);
 354                 goto err_unreg_spi_device;
 355         }
 356
 357         platform_set_drvdata(pdev, ucmb);
 358
 359         printk(KERN_INFO PFX "Registered message bus \"%s\"\n", pdata->name);
 360
 361         return 0;
 362
 363 err_unreg_spi_device:
 364         spi_unregister_device(ucmb->sdev);
 365 err_free_spi_device:
 366         spi_dev_put(ucmb->sdev);
 367 err_unreg_spi_gpio_pdev:
 368         platform_device_unregister(&ucmb->spi_gpio_pdev);
 369 err_free_ucmb:
 370         kfree(ucmb);
 371
 372         return err;
 373 }
 374
 375 static int __devexit ucmb_remove(struct platform_device *pdev)
 376 {
 377         struct ucmb *ucmb = platform_get_drvdata(pdev);
 378         int err;
 379
 380         err = misc_deregister(&ucmb->mdev);
 381         if (err) {
 382                 printk(KERN_ERR PFX "Failed to unregister miscdev %s\n",
 383                        ucmb->mdev.name);
 384         }
 385         spi_unregister_device(ucmb->sdev);
 386         spi_dev_put(ucmb->sdev);
 387         platform_device_unregister(&ucmb->spi_gpio_pdev);
 388
 389         kfree(ucmb);
 390         platform_set_drvdata(pdev, NULL);
 391
 392         return 0;
 393 }
 394
 395 static struct platform_driver ucmb_driver = {
 396         .driver         = {
 397                 .name   = "ucmb",
 398                 .owner  = THIS_MODULE,
 399         },
 400         .probe          = ucmb_probe,
 401         .remove         = __devexit_p(ucmb_probe),
 402 };
 403
 404 static int ucmb_modinit(void)
 405 {
 406         struct ucmb_platform_data *pdata;
 407         struct platform_device *pdev;
 408         int err, i;
 409
 410         printk(KERN_INFO "Microcontroller message bus driver\n");
 411
 412         err = platform_driver_register(&ucmb_driver);
 413         if (err) {
 414                 printk(KERN_ERR PFX "Failed to register platform driver\n");
 415                 return err;
 416         }
 417         err = spi_register_driver(&ucmb_spi_driver);
 418         if (err) {
 419                 printk(KERN_ERR PFX "Failed to register SPI driver\n");
 420                 platform_driver_unregister(&ucmb_driver);
 421                 return err;
 422         }
 423
 424         for (i = 0; i < ARRAY_SIZE(ucmb_list); i++) {
 425                 pdata = &ucmb_list[i];
 426
 427                 pdev = platform_device_alloc("ucmb", i);
 428                 if (!pdev) {
 429                         printk(KERN_ERR PFX "Failed to allocate platform device.\n");
 430                         break;
 431                 }
 432                 err = platform_device_add_data(pdev, pdata, sizeof(*pdata));
 433                 if (err) {
 434                         printk(KERN_ERR PFX "Failed to add platform data.\n");
 435                         platform_device_put(pdev);
 436                         break;
 437                 }
 438                 err = platform_device_add(pdev);
 439                 if (err) {
 440                         printk(KERN_ERR PFX "Failed to register platform device.\n");
 441                         platform_device_put(pdev);
 442                         break;
 443                 }
 444                 pdata->pdev = pdev;
 445         }
 446
 447         return 0;
 448 }
 449 module_init(ucmb_modinit);
 450
 451 static void ucmb_modexit(void)
 452 {
 453         struct ucmb_platform_data *pdata;
 454         int i;
 455
 456         for (i = 0; i < ARRAY_SIZE(ucmb_list); i++) {
 457                 pdata = &ucmb_list[i];
 458
 459                 if (pdata->pdev) {
 460                         platform_device_unregister(pdata->pdev);
 461                         platform_device_put(pdata->pdev);
 462                 }
 463         }
 464         spi_unregister_driver(&ucmb_spi_driver);
 465         platform_driver_unregister(&ucmb_driver);
 466 }
 467 module_exit(ucmb_modexit);