设备与驱动匹配1.match过程i2c_add_driver-->i2c_register_driver-->i2c_bus_type-->.match->i2c_device_match-->of_driver_match_device/i2c_match_id(比较i2c_driver->id_table->name和client->name,如果相同,则匹配上,匹配上之后,运行driver_register调用driver_probe_device进行设备与驱动绑定。),////////////static int __init at24_init(void){ io_limit = rounddown_pow_of_two(io_limit);//执行完i2c_add_numbered_adapter函数后,内核的i2c总线上已有adapter device和client device// .id_table = at24_ids中的名字和i2c_client中的名字 进行匹配 return i2c_add_driver(&at24_driver);}module_init(at24_init);////////////////////////////////////////////////////////////////////////////////static struct i2c_driver at24_driver = { .driver = { .name = "at24",//这个名字用于创建文件,不用于匹配 .owner = THIS_MODULE, }, ///当i2c_client和i2c_driver(at24_driver)匹配时调用 .probe = at24_probe, .remove = __devexit_p(at24_remove),//ID表是用来和i2c_client匹配用的,// static struct i2c_board_info i2c_devs0[]用来建立i2c_client(相当于device)////int i2c_attach_client(struct i2c_client *client)//i2c_new_device函数 .id_table = at24_ids,};////////////////////////////////////////////////////////////////////////////////////////////////struct i2c_client *i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)// ------> strlcpy(client->name, info->type, sizeof(client->name));// i2c_board_info中的名字给了client//static struct i2c_board_info i2c_devs0[]////"24c08"这个名字就是用来创建i2c_client来和里static struct i2c_driver at24_driver进行匹配的。static const struct i2c_device_id at24_ids[] = { /* needs 8 addresses as A0-A2 are ignored */ /* old variants can't be handled with this generic entry! */ { "24c01", AT24_DEVICE_MAGIC(1024 / 8, 0) }, { "24c02", AT24_DEVICE_MAGIC(2048 / 8, 0) }, /* spd is a 24c02 in memory DIMMs */ { "spd", AT24_DEVICE_MAGIC(2048 / 8, AT24_FLAG_READONLY | AT24_FLAG_IRUGO) }, { "24c04", AT24_DEVICE_MAGIC(4096 / 8, 0) }, /* 24rf08 quirk is handled at i2c-core */ { "24c08", AT24_DEVICE_MAGIC(8192 / 8, 0) }, { "24c16", AT24_DEVICE_MAGIC(16384 / 8, 0) }, { "24c32", AT24_DEVICE_MAGIC(32768 / 8, AT24_FLAG_ADDR16) }, { "24c64", AT24_DEVICE_MAGIC(65536 / 8, AT24_FLAG_ADDR16) }, { "at24", 0 }, { /* END OF LIST */ }};/////////////////////////////////////////////////////////////////////////////////////////////*-------------------------------------------------------------------------*/static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id){ struct at24_platform_data chip; bool writable; bool use_smbus = false; struct at24_data *at24; int err; unsigned i, num_addresses; kernel_ulong_t magic; if (client->dev.platform_data) { chip = *(struct at24_platform_data *)client->dev.platform_data; } magic = id->driver_data; chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN)); magic >>= AT24_SIZE_BYTELEN; chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS); /* * This is slow, but we can't know all eeproms, so we better * play safe. Specifying custom eeprom-types via platform_data * is recommended anyhow. */ chip.page_size = 1; } if (!is_power_of_2(chip.byte_len)) dev_warn(&client->dev, "byte_len looks suspicious (no power of 2)!\n"); if (!is_power_of_2(chip.page_size)) dev_warn(&client->dev, "page_size looks suspicious (no power of 2)!\n"); /* Use I2C operations unless we're stuck with SMBus extensions. */ if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) { if (chip.flags & AT24_FLAG_ADDR16) { err = -EPFNOSUPPORT; goto err_out; } if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) { err = -EPFNOSUPPORT; goto err_out; } use_smbus = true; } if (chip.flags & AT24_FLAG_TAKE8ADDR) num_addresses = 8; else num_addresses = DIV_ROUND_UP(chip.byte_len, (chip.flags & AT24_FLAG_ADDR16) ? 65536 : 256); at24 = kzalloc(sizeof(struct at24_data) + num_addresses * sizeof(struct i2c_client *), GFP_KERNEL); if (!at24) { err = -ENOMEM; goto err_out; } mutex_init(&at24->lock); at24->use_smbus = use_smbus; at24->chip = chip; at24->num_addresses = num_addresses; /* * Export the EEPROM bytes through sysfs, since that's convenient. * By default, only root should see the data (maybe passwords etc) */ at24->bin.attr.name = "eeprom"; at24->bin.attr.mode = chip.flags & AT24_FLAG_IRUGO ? S_IRUGO : S_IRUSR;//除了这种操作i2c设备的方法外,////static int __init i2c_dev_init(void)//res = register_chrdev(I2C_MAJOR, "i2c", &i2cdev_fops); 也是一种操作i2c设备的方法 at24->bin.read = at24_bin_read; at24->bin.size = chip.byte_len; writable = !(chip.flags & AT24_FLAG_READONLY); if (writable) { if (!use_smbus || i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) { unsigned write_max = chip.page_size; at24->bin.write = at24_bin_write; at24->bin.attr.mode |= S_IWUSR; if (write_max > io_limit) write_max = io_limit; if (use_smbus && write_max > I2C_SMBUS_BLOCK_MAX) write_max = I2C_SMBUS_BLOCK_MAX; at24->write_max = write_max; /* buffer (data + address at the beginning) */ at24->writebuf = kmalloc(write_max + 2, GFP_KERNEL); } } at24->client[0] = client; /* use dummy devices for multiple-address chips */ for (i = 1; i at24->client[i] = i2c_new_dummy(client->adapter, client->addr + i); if (!at24->client[i]) { dev_err(&client->dev, "address 0x%02x unavailable\n", client->addr + i); err = -EADDRINUSE; goto err_clients; } } err = sysfs_create_bin_file(&client->dev.kobj, &at24->bin); if (err) goto err_clients; i2c_set_clientdata(client, at24); dev_info(&client->dev, "%zu byte %s EEPROM %s\n", at24->bin.size, client->name, writable ? "(writable)" : "(read-only)"); dev_dbg(&client->dev, "page_size %d, num_addresses %d, write_max %d%s\n", chip.page_size, num_addresses, at24->write_max, use_smbus ? ", use_smbus" : ""); return 0;err_clients: for (i = 1; i if (at24->client[i]) i2c_unregister_device(at24->client[i]); kfree(at24->writebuf);err_struct: kfree(at24);err_out: dev_dbg(&client->dev, "probe error %d\n", err); return err;}////////////////////////////////////////////////////////////////////////////////////////////static ssize_t at24_bin_read(struct kobject *kobj, struct bin_attribute *attr, char *buf, loff_t off, size_t count){ struct at24_data *at24; ssize_t retval = 0; at24 = dev_get_drvdata(container_of(kobj, struct device, kobj)); /* * Read data from chip, protecting against concurrent updates * from this host, but not from other I2C masters. */ mutex_lock(&at24->lock); while (count) { ssize_t status; status = at24_eeprom_read(at24, buf, off, count); if (status if (retval == 0) retval = status; break; } buf += status; off += status; count -= status; retval += status; } mutex_unlock(&at24->lock); return retval;}////////////////////////////////////////////////////////////////////////////////////////////static ssize_t at24_eeprom_read(struct at24_data *at24, char *buf, unsigned offset, size_t count){ struct i2c_msg msg[2]; u8 msgbuf[2]; struct i2c_client *client; int status, i; memset(msg, 0, sizeof(msg)); /* * REVISIT some multi-address chips don't rollover page reads to * the next slave address, so we may need to truncate the count. * Those chips might need another quirk flag. * * If the real hardware used four adjacent 24c02 chips and that * were misconfigured as one 24c08, that would be a similar effect: * one "eeprom" file not four, but larger reads would fail when * they crossed certain pages. */ /* * Slave address and byte offset derive from the offset. Always * set the byte address; on a multi-master board, another master * may have changed the chip's "current" address pointer. */ client = at24_translate_offset(at24, &offset); if (count > io_limit) count = io_limit; /* Smaller eeproms can work given some SMBus extension calls */ if (at24->use_smbus) { if (count > I2C_SMBUS_BLOCK_MAX) count = I2C_SMBUS_BLOCK_MAX; status = i2c_smbus_read_i2c_block_data(client, offset, count, buf); dev_dbg(&client->dev, "smbus read %zu@%d --> %d\n", count, offset, status); return (status } /* * When we have a better choice than SMBus calls, use a combined * I2C message. Write address; then read up to io_limit data bytes. * Note that read page rollover helps us here (unlike writes). * msgbuf is u8 and will cast to our needs. */ i = 0; if (at24->chip.flags & AT24_FLAG_ADDR16) msgbuf[i++] = offset >> 8; msgbuf[i++] = offset; msg[0].addr = client->addr; msg[0].buf = msgbuf; msg[0].len = i; msg[1].addr = client->addr; msg[1].flags = I2C_M_RD; msg[1].buf = buf; msg[1].len = count; 中有i2c_transfer status = i2c_transfer(client->adapter, msg, 2); dev_dbg(&client->dev, "i2c read %zu@%d --> %d\n", count, offset, status); if (status == 2) return count; else if (status >= 0) return -EIO; else return status;}