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  • SPI驱动程序设计

    一、SPI驱动子系统架构
    m25p80.c:
    1. static int __devinit m25p_probe(struct spi_device *spi)
    2. {
    3.     struct flash_platform_data    *data;
    4.     struct m25p            *flash;
    5.     struct flash_info        *info;
    6.     unsigned            i;

    8.     data = spi->dev.platform_data;
    9.     if (data && data->type) {                                       //配对设备，在m25p_data中找是否有对应的ID
    10.         for (i = 0, info = m25p_data;
    11.                 i < ARRAY_SIZE(m25p_data);
    12.                 i++, info++) {
    13.             if (strcmp(data->type, info->name) == 0)
    14.                 break;
    15.         }

    17.         /* unrecognized chip? */                                   //芯片没有被认出
    18.         if (i == ARRAY_SIZE(m25p_data)) {
    19.             DEBUG(MTD_DEBUG_LEVEL0, "%s: unrecognized id %s ",
    20.                     dev_name(&spi->dev), data->type);
    21.             info = NULL;

    23.         /* recognized; is that chip really what's there? */                //找到芯片
    24.         } else if (info->jedec_id) {
    25.             struct flash_info    *chip = jedec_probe(spi);

    27.             if (!chip || chip != info) {
    28.                 dev_warn(&spi->dev, "found %s, expected %s ",
    29.                         chip ? chip->name : "UNKNOWN",
    30.                         info->name);
    31.                 info = NULL;
    32.             }
    33.         }
    34.     } else
    35.         info = jedec_probe(spi);

    37.     if (!info)
    38.         return -ENODEV;

    40.     flash = kzalloc(sizeof *flash, GFP_KERNEL);                                    //分配空间
    41.     if (!flash)
    42.         return -ENOMEM;

    44.     flash->spi = spi;
    45.     mutex_init(&flash->lock);
    46.     dev_set_drvdata(&spi->dev, flash);

    48.     /*
    49.      * Atmel serial flash tend to power up
    50.      * with the software protection bits set
    51.      */

    53.     if (info->jedec_id >> 16 == 0x1f) {
    54.         write_enable(flash);
    55.         write_sr(flash, 0);
    56.     }

    58.     if (data && data->name)
    59.         flash->mtd.name = data->name;
    60.     else
    61.         flash->mtd.name = dev_name(&spi->dev);

    63.     flash->mtd.type = MTD_NORFLASH;                                                  //初始化操作集
    64.     flash->mtd.writesize = 1;
    65.     flash->mtd.flags = MTD_CAP_NORFLASH;
    66.     flash->mtd.size = info->sector_size * info->n_sectors;
    67.     flash->mtd.erase = m25p80_erase;
    68.     flash->mtd.read = m25p80_read;
    69.     flash->mtd.write = m25p80_write;

    71.     /* prefer "small sector" erase if possible */
    72.     if (info->flags & SECT_4K) {
    73.         flash->erase_opcode = OPCODE_BE_4K;
    74.         flash->mtd.erasesize = 4096;
    75.     } else {
    76.         flash->erase_opcode = OPCODE_SE;
    77.         flash->mtd.erasesize = info->sector_size;
    78.     }

    80.     flash->mtd.dev.parent = &spi->dev;

    82.     dev_info(&spi->dev, "%s (%lld Kbytes) ", info->name,
    83.             (long long)flash->mtd.size >> 10);

    85.     DEBUG(MTD_DEBUG_LEVEL2,
    86.         "mtd .name = %s, .size = 0x%llx (%lldMiB) "
    87.             ".erasesize = 0x%.8x (%uKiB) .numeraseregions = %d ",
    88.         flash->mtd.name,
    89.         (long long)flash->mtd.size, (long long)(flash->mtd.size >> 20),
    90.         flash->mtd.erasesize, flash->mtd.erasesize / 1024,
    91.         flash->mtd.numeraseregions);

    93.     if (flash->mtd.numeraseregions)
    94.         for (i = 0; i < flash->mtd.numeraseregions; i++)
    95.             DEBUG(MTD_DEBUG_LEVEL2,
    96.                 "mtd.eraseregions[%d] = { .offset = 0x%llx, "
    97.                 ".erasesize = 0x%.8x (%uKiB), "
    98.                 ".numblocks = %d } ",
    99.                 i, (long long)flash->mtd.eraseregions[i].offset,
    100.                 flash->mtd.eraseregions[i].erasesize,
    101.                 flash->mtd.eraseregions[i].erasesize / 1024,
    102.                 flash->mtd.eraseregions[i].numblocks);


    105.     /* partitions should match sector boundaries; and it may be good to
    106.      * use readonly partitions for writeprotected sectors (BP2..BP0).
    107.      */
    108.     if (mtd_has_partitions()) {
    109.         struct mtd_partition    *parts = NULL;
    110.         int            nr_parts = 0;

    112.         if (mtd_has_cmdlinepart()) {
    113.             static const char *part_probes[]
    114.                     = { "cmdlinepart", NULL, };

    116.             nr_parts = parse_mtd_partitions(&flash->mtd,
    117.                     part_probes, &parts, 0);
    118.         }

    120.         if (nr_parts <= 0 && data && data->parts) {
    121.             parts = data->parts;
    122.             nr_parts = data->nr_parts;
    123.         }

    125.         if (nr_parts > 0) {
    126.             for (i = 0; i < nr_parts; i++) {
    127.                 DEBUG(MTD_DEBUG_LEVEL2, "partitions[%d] = "
    128.                     "{.name = %s, .offset = 0x%llx, "
    129.                         ".size = 0x%llx (%lldKiB) } ",
    130.                     i, parts[i].name,
    131.                     (long long)parts[i].offset,
    132.                     (long long)parts[i].size,
    133.                     (long long)(parts[i].size >> 10));
    134.             }
    135.             flash->partitioned = 1;
    136.             return add_mtd_partitions(&flash->mtd, parts, nr_parts);
    137.         }
    138.     } else if (data->nr_parts)
    139.         dev_warn(&spi->dev, "ignoring %d default partitions on %s ",
    140.                 data->nr_parts, data->name);

    142.     return add_mtd_device(&flash->mtd) == 1 ? -ENODEV : 0;
    143. }
    m25p_write:
    1. static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
    2.     size_t *retlen, const u_char *buf)
    3. {
    4.     struct m25p *flash = mtd_to_m25p(mtd);
    5.     u32 page_offset, page_size;
    6.     struct spi_transfer t[2];                                                  //重要结构，一次发送
    7.     struct spi_message m;                                                      //重要结构，消息结构

    9.     DEBUG(MTD_DEBUG_LEVEL2, "%s: %s %s 0x%08x, len %zd ",
    10.             dev_name(&flash->spi->dev), __func__, "to",
    11.             (u32)to, len);

    13.     if (retlen)
    14.         *retlen = 0;

    16.     /* sanity checks */
    17.     if (!len)
    18.         return(0);

    20.     if (to + len > flash->mtd.size)
    21.         return -EINVAL;

    23.     spi_message_init(&m);                                                  //这边进行了初始化
    24.     memset(t, 0, (sizeof t));                                              //清空

    26.     t[0].tx_buf = flash->command;
    27.     t[0].len = CMD_SIZE;
    28.     spi_message_add_tail(&t[0], &m);                                       //把数据挂汲取

    30.     t[1].tx_buf = buf;
    31.     spi_message_add_tail(&t[1], &m);

    33.     mutex_lock(&flash->lock);

    35.     /* Wait until finished previous write command. */
    36.     if (wait_till_ready(flash)) {
    37.         mutex_unlock(&flash->lock);
    38.         return 1;
    39.     }

    41.     write_enable(flash);

    43.     /* Set up the opcode in the write buffer. */                            //数据发送
    44.     flash->command[0] = OPCODE_PP;
    45.     flash->command[1] = to >> 16;
    46.     flash->command[2] = to >> 8;
    47.     flash->command[3] = to;

    49.     /* what page do we start with? */
    50.     page_offset = to % FLASH_PAGESIZE;

    52.     /* do all the bytes fit onto one page? */
    53.     if (page_offset + len <= FLASH_PAGESIZE) {
    54.         t[1].len = len;

    56.         spi_sync(flash->spi, &m);                                            //把message提交给控制器

    58.         *retlen = m.actual_length - CMD_SIZE;
    59.     } else {
    60.         u32 i;

    62.         /* the size of data remaining on the first page */
    63.         page_size = FLASH_PAGESIZE - page_offset;

    65.         t[1].len = page_size;
    66.         spi_sync(flash->spi, &m);

    68.         *retlen = m.actual_length - CMD_SIZE;

    70.         /* write everything in PAGESIZE chunks */
    71.         for (i = page_size; i < len; i += page_size) {
    72.             page_size = len - i;
    73.             if (page_size > FLASH_PAGESIZE)
    74.                 page_size = FLASH_PAGESIZE;

    76.             /* write the next page to flash */
    77.             flash->command[1] = (to + i) >> 16;
    78.             flash->command[2] = (to + i) >> 8;
    79.             flash->command[3] = (to + i);

    81.             t[1].tx_buf = buf + i;
    82.             t[1].len = page_size;

    84.             wait_till_ready(flash);

    86.             write_enable(flash);

    88.             spi_sync(flash->spi, &m);

    90.             if (retlen)
    91.                 *retlen += m.actual_length - CMD_SIZE;
    92.         }
    93.     }

    95.     mutex_unlock(&flash->lock);

    97.     return 0;
    98. }

    spi_master是SPI控制器，其中的queue把spi_message串成链表。这是一次SPI事务，而一个事务又分成一个一个的读写发送操作（spi_transfer）。


    无欲速，无见小利。欲速，则不达；见小利，则大事不成。
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  • 原文地址：https://www.cnblogs.com/ch122633/p/7363290.html
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