?

I2C驅動分為3層：
1. I2C BUS驅動

2. I2C核心層(協議相關)

3. I2C chip

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I2C BUS 驅動分析：drivers\i2c\busses\i2c-s3c2410.c
1. 分配一個i2c_adapter
2. 設置: 實現發出I2C命令、數據的函數
3. 注冊：i2c_add_adapter
4. 硬件相關的設置

I2C chip驅動分析：drivers\i2c\chips\ds1337.c
ds1337_init
??? i2c_add_driver(&ds1337_driver);? /* 添加driver */
1. 分配i2c_driver
2. 設置: i2c_driver里有一個attach_adapter,用來識別是否存在I2C設備
3. 注冊: i2c_add_driver

?

static struct i2c_driver ds1337_driver = {
??? .driver = {
??????? .name?? = "ds1337",
??? },
??? .attach_adapter = ds1337_attach_adapter,
??? .detach_client? = ds1337_detach_client,
??? .command??? = ds1337_command,
};?

drivers\i2c\busses\i2c-s3c2410.c:

??? i2c_add_adapter => i2c_register_adapter => i2c_driver.attach_adapter
???
??? i2c_register_driver => i2c_driver.attach_adapter
???????
???????
???????
???????
??????????? i2c_driver.attach_adapter? //ds1337_attach_adapter
??????????????? i2c_probe(adapter, &addr_data, ds1337_detect);
??????????????????? ds1337_detect
??????????????????????? i2c_attach_client? /* 添加設備 */??

?

分析drivers\i2c\chips\ds1337.c
ds1337_init
??? i2c_add_driver(&ds1337_driver);
??????? i2c_register_driver
??????????? // 把i2c_drvier放入鍵表
???????????
??????????? // 對每一個adapter(發出I2C信息的能力)，調用attach_adapter
??????????? list_for_each_entry(adapter, &adapters, list) {
??????????????? driver->attach_adapter(adapter);
??????????????????????? ds1337_attach_adapter // 識別I2C設備
???????????????????????
??????????????????????????? // i2c-core.c
??????????????????????????? i2c_probe(adapter, &addr_data, ds1337_detect);
??????????????????????????????? i2c_probe_address(adapter, addr, kind, found_proc)
??????????????????????????????????? err = found_proc(adapter, addr, kind);
??????????????????????????????????????????? ds1337_detect(adapter, 0x68, xxxxx)
??????????????????????????????????????????????? // 分配一個i2c_client
??????????????????????????????????????????????? // 設置
???????????????????????????????????????????????
??????????????????????????????????????????????? // 讀I2C設備，確定該設備確實存在
??????????????????????????????????????????????? ds1337_read(new_client, DS1337_REG_STATUS, &data)
??????????????????????????????????????????????????? i2c_smbus_read_byte_data
??????????????????????????????????????????????????????? i2c_smbus_xfer
??????????????????????????????????????????????????????????? // s3c24xx_i2c_algorithm
??????????????????????????????????????????????????????????? adapter->algo->smbus_xfer

/*
?*? linux/drivers/i2c/chips/ds1337.c
?*
?*? Copyright (C) 2005 James Chapman <jchapman@katalix.com>
?*
?*?based on linux/drivers/acorn/char/pcf8583.c
?*? Copyright (C) 2000 Russell King
?*
?* This program is free software; you can redistribute it and/or modify
?* it under the terms of the GNU General Public License version 2 as
?* published by the Free Software Foundation.
?*
?* Driver for Dallas Semiconductor DS1337 and DS1339 real time clock chip
?*/

#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/string.h>
#include <linux/rtc.h>??/* get the user-level API */
#include <linux/bcd.h>
#include <linux/list.h>

/* Device registers */
#define DS1337_REG_HOUR??2
#define DS1337_REG_DAY??3
#define DS1337_REG_DATE??4
#define DS1337_REG_MONTH?5
#define DS1337_REG_CONTROL?14
#define DS1337_REG_STATUS?15

/* FIXME - how do we export these interface constants? */
#define DS1337_GET_DATE??0
#define DS1337_SET_DATE??1

/*
?* Functions declaration
?*/
static unsigned short normal_i2c[] = { 0x68, I2C_CLIENT_END };

I2C_CLIENT_INSMOD_1(ds1337);

static int ds1337_attach_adapter(struct i2c_adapter *adapter);
static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind);
static void ds1337_init_client(struct i2c_client *client);
static int ds1337_detach_client(struct i2c_client *client);
static int ds1337_command(struct i2c_client *client, unsigned int cmd,
???? void *arg);

/*
?* Driver data (common to all clients)
?*/
static struct i2c_driver ds1337_driver = {
?.driver = {
??.name?= "ds1337",
?},
?.attach_adapter?= ds1337_attach_adapter,
?.detach_client?= ds1337_detach_client,
?.command?= ds1337_command,
};

/*
?* Client data (each client gets its own)
?*/
struct ds1337_data {
?struct i2c_client client;
?struct list_head list;
};

/*
?* Internal variables
?*/
static LIST_HEAD(ds1337_clients);

static inline int ds1337_read(struct i2c_client *client, u8 reg, u8 *value)
{
?s32 tmp = i2c_smbus_read_byte_data(client, reg);

?if (tmp < 0)
??return -EIO;

?*value = tmp;

?return 0;
}

/*
?* Chip access functions
?*/
static int ds1337_get_datetime(struct i2c_client *client, struct rtc_time *dt)
{
?int result;
?u8 buf[7];
?u8 val;
?struct i2c_msg msg[2];
?u8 offs = 0;

?if (!dt) {
??dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
??return -EINVAL;
?}

?msg[0].addr = client->addr;
?msg[0].flags = 0;
?msg[0].len = 1;
?msg[0].buf = &offs;

?msg[1].addr = client->addr;
?msg[1].flags = I2C_M_RD;
?msg[1].len = sizeof(buf);
?msg[1].buf = &buf[0];

?result = i2c_transfer(client->adapter, msg, 2);

?dev_dbg(&client->dev, "%s: [%d] %02x %02x %02x %02x %02x %02x %02x\n",
??__FUNCTION__, result, buf[0], buf[1], buf[2], buf[3],
??buf[4], buf[5], buf[6]);

?if (result == 2) {
??dt->tm_sec = BCD2BIN(buf[0]);
??dt->tm_min = BCD2BIN(buf[1]);
??val = buf[2] & 0x3f;
??dt->tm_hour = BCD2BIN(val);
??dt->tm_wday = BCD2BIN(buf[3]) - 1;
??dt->tm_mday = BCD2BIN(buf[4]);
??val = buf[5] & 0x7f;
??dt->tm_mon = BCD2BIN(val) - 1;
??dt->tm_year = BCD2BIN(buf[6]);
??if (buf[5] & 0x80)
???dt->tm_year += 100;

??dev_dbg(&client->dev, "%s: secs=%d, mins=%d, "
???"hours=%d, mday=%d, mon=%d, year=%d, wday=%d\n",
???__FUNCTION__, dt->tm_sec, dt->tm_min,
???dt->tm_hour, dt->tm_mday,
???dt->tm_mon, dt->tm_year, dt->tm_wday);

??return 0;
?}

?dev_err(&client->dev, "error reading data! %d\n", result);
?return -EIO;
}

static int ds1337_set_datetime(struct i2c_client *client, struct rtc_time *dt)
{
?int result;
?u8 buf[8];
?u8 val;
?struct i2c_msg msg[1];

?if (!dt) {
??dev_dbg(&client->dev, "%s: EINVAL: dt=NULL\n", __FUNCTION__);
??return -EINVAL;
?}

?dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
??"mday=%d, mon=%d, year=%d, wday=%d\n", __FUNCTION__,
??dt->tm_sec, dt->tm_min, dt->tm_hour,
??dt->tm_mday, dt->tm_mon, dt->tm_year, dt->tm_wday);

?buf[0] = 0;??/* reg offset */
?buf[1] = BIN2BCD(dt->tm_sec);
?buf[2] = BIN2BCD(dt->tm_min);
?buf[3] = BIN2BCD(dt->tm_hour);
?buf[4] = BIN2BCD(dt->tm_wday + 1);
?buf[5] = BIN2BCD(dt->tm_mday);
?buf[6] = BIN2BCD(dt->tm_mon + 1);
?val = dt->tm_year;
?if (val >= 100) {
??val -= 100;
??buf[6] |= (1 << 7);
?}
?buf[7] = BIN2BCD(val);

?msg[0].addr = client->addr;
?msg[0].flags = 0;
?msg[0].len = sizeof(buf);
?msg[0].buf = &buf[0];

?result = i2c_transfer(client->adapter, msg, 1);
?if (result == 1)
??return 0;

?dev_err(&client->dev, "error writing data! %d\n", result);
?return -EIO;
}

static int ds1337_command(struct i2c_client *client, unsigned int cmd,
???? void *arg)
{
?dev_dbg(&client->dev, "%s: cmd=%d\n", __FUNCTION__, cmd);

?switch (cmd) {
?case DS1337_GET_DATE:
??return ds1337_get_datetime(client, arg);

?case DS1337_SET_DATE:
??return ds1337_set_datetime(client, arg);

?default:
??return -EINVAL;
?}
}

/*
?* Public API for access to specific device. Useful for low-level
?* RTC access from kernel code.
?*/
int ds1337_do_command(int bus, int cmd, void *arg)
{
?struct list_head *walk;
?struct list_head *tmp;
?struct ds1337_data *data;

?list_for_each_safe(walk, tmp, &ds1337_clients) {
??data = list_entry(walk, struct ds1337_data, list);
??if (data->client.adapter->nr == bus)
???return ds1337_command(&data->client, cmd, arg);
?}

?return -ENODEV;
}

static int ds1337_attach_adapter(struct i2c_adapter *adapter)
{
?return i2c_probe(adapter, &addr_data, ds1337_detect);
}

/*
?* The following function does more than just detection. If detection
?* succeeds, it also registers the new chip.
?*/
static int ds1337_detect(struct i2c_adapter *adapter, int address, int kind)
{
?struct i2c_client *new_client;
?struct ds1337_data *data;
?int err = 0;
?const char *name = "";

?if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
???????? I2C_FUNC_I2C))
??goto exit;

?if (!(data = kzalloc(sizeof(struct ds1337_data), GFP_KERNEL))) {
??err = -ENOMEM;
??goto exit;
?}
?INIT_LIST_HEAD(&data->list);

?/* The common I2C client data is placed right before the
? * DS1337-specific data.
? */
?new_client = &data->client;
?i2c_set_clientdata(new_client, data);
?new_client->addr = address;
?new_client->adapter = adapter;
?new_client->driver = &ds1337_driver;
?new_client->flags = 0;

?/*
? * Now we do the remaining detection. A negative kind means that
? * the driver was loaded with no force parameter (default), so we
? * must both detect and identify the chip. A zero kind means that
? * the driver was loaded with the force parameter, the detection
? * step shall be skipped. A positive kind means that the driver
? * was loaded with the force parameter and a given kind of chip is
? * requested, so both the detection and the identification steps
? * are skipped.
? *
? * For detection, we read registers that are most likely to cause
? * detection failure, i.e. those that have more bits with fixed
? * or reserved values.
? */

?/* Default to an DS1337 if forced */
?if (kind == 0)
??kind = ds1337;

?if (kind < 0) {??/* detection and identification */
??u8 data;

??/* Check that status register bits 6-2 are zero */
??if ((ds1337_read(new_client, DS1337_REG_STATUS, &data) < 0) ||
????? (data & 0x7c))
???goto exit_free;

??/* Check for a valid day register value */
??if ((ds1337_read(new_client, DS1337_REG_DAY, &data) < 0) ||
????? (data == 0) || (data & 0xf8))
???goto exit_free;

??/* Check for a valid date register value */
??if ((ds1337_read(new_client, DS1337_REG_DATE, &data) < 0) ||
????? (data == 0) || (data & 0xc0) || ((data & 0x0f) > 9) ||
????? (data >= 0x32))
???goto exit_free;

??/* Check for a valid month register value */
??if ((ds1337_read(new_client, DS1337_REG_MONTH, &data) < 0) ||
????? (data == 0) || (data & 0x60) || ((data & 0x0f) > 9) ||
????? ((data >= 0x13) && (data <= 0x19)))
???goto exit_free;

??/* Check that control register bits 6-5 are zero */
??if ((ds1337_read(new_client, DS1337_REG_CONTROL, &data) < 0) ||
????? (data & 0x60))
???goto exit_free;

??kind = ds1337;
?}

?if (kind == ds1337)
??name = "ds1337";

?/* We can fill in the remaining client fields */
?strlcpy(new_client->name, name, I2C_NAME_SIZE);

?/* Tell the I2C layer a new client has arrived */
?if ((err = i2c_attach_client(new_client)))
??goto exit_free;

?/* Initialize the DS1337 chip */
?ds1337_init_client(new_client);

?/* Add client to local list */
?list_add(&data->list, &ds1337_clients);

?return 0;

exit_free:
?kfree(data);
exit:
?return err;
}

static void ds1337_init_client(struct i2c_client *client)
{
?u8 status, control;

?/* On some boards, the RTC isn't configured by boot firmware.
? * Handle that case by starting/configuring the RTC now.
? */
?status = i2c_smbus_read_byte_data(client, DS1337_REG_STATUS);
?control = i2c_smbus_read_byte_data(client, DS1337_REG_CONTROL);

?if ((status & 0x80) || (control & 0x80)) {
??/* RTC not running */
??u8 buf[1+16];?/* First byte is interpreted as address */
??struct i2c_msg msg[1];

??dev_dbg(&client->dev, "%s: RTC not running!\n", __FUNCTION__);

??/* Initialize all, including STATUS and CONTROL to zero */
??memset(buf, 0, sizeof(buf));

??/* Write valid values in the date/time registers */
??buf[1+DS1337_REG_DAY] = 1;
??buf[1+DS1337_REG_DATE] = 1;
??buf[1+DS1337_REG_MONTH] = 1;

??msg[0].addr = client->addr;
??msg[0].flags = 0;
??msg[0].len = sizeof(buf);
??msg[0].buf = &buf[0];

??i2c_transfer(client->adapter, msg, 1);
?} else {
??/* Running: ensure that device is set in 24-hour mode */
??s32 val;

??val = i2c_smbus_read_byte_data(client, DS1337_REG_HOUR);
??if ((val >= 0) && (val & (1 << 6)))
???i2c_smbus_write_byte_data(client, DS1337_REG_HOUR,
??????? val & 0x3f);
?}
}

static int ds1337_detach_client(struct i2c_client *client)
{
?int err;
?struct ds1337_data *data = i2c_get_clientdata(client);

?if ((err = i2c_detach_client(client)))
??return err;

?list_del(&data->list);
?kfree(data);
?return 0;
}

static int __init ds1337_init(void)
{
?return i2c_add_driver(&ds1337_driver);
}

static void __exit ds1337_exit(void)
{
?i2c_del_driver(&ds1337_driver);
}

MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
MODULE_DESCRIPTION("DS1337 RTC driver");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL_GPL(ds1337_do_command);

module_init(ds1337_init);
module_exit(ds1337_exit);

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