linux(七):I2C(touch screen)

? ? ? ? 本文主要探讨210触摸屏驱动相关知识。

I2C子系统
????????i2c子系统组成部分:I2C核心,I2C总线驱动,I2C设备驱动
????????I2C核心：I2C总线驱动和设备驱动注册注销方法
????????I2C总线驱动：I2C适配器(I2C控制器)控制,用于I2C读写时序(I2C_adapter、i2c_algorithm)
????????I2C设备驱动：I2C适配器与CPU交换数据(i2c_driver、i2c_client)

?

结构体

struct i2c_adapter {
?? ?struct module *owner;
?? ?unsigned int id;
?? ?unsigned int class;?? ??? ? ?/* classes to allow probing for */
?? ?const struct i2c_algorithm *algo; /* the algorithm to access the bus */
?? ?void *algo_data;

?? ?/* data fields that are valid for all devices?? ?*/
?? ?struct rt_mutex bus_lock;

?? ?int timeout;?? ??? ??? ?/* in jiffies */
?? ?int retries;
?? ?struct device dev;?? ??? ?/* the adapter device */

?? ?int nr;
?? ?char name[48];
?? ?struct completion dev_released;

?? ?struct list_head userspace_clients;
};

????????int nr;;i2c适配器id号
????????unsigned int class;i2c适配器适配器类(/sys/class/i2c-adapter)
????????const struct i2c_algorithm *algo;void *algo_data;i2c适配器通信方法
????????struct device dev;i2c适配器设备
????????char name[48];i2c适配器名称
????????struct list_head userspace_clients;挂接与适配器匹配成功的从设备i2c_client的链表头
用于i2c适配器描述(I2C控制器)

struct i2c_algorithm {
?? ?
?? ?int (*master_xfer)(struct i2c_adapter *adap, struct i2c_msg *msgs,
?? ??? ??? ? ? int num);
?? ?int (*smbus_xfer) (struct i2c_adapter *adap, u16 addr,
?? ??? ??? ? ? unsigned short flags, char read_write,
?? ??? ??? ? ? u8 command, int size, union i2c_smbus_data *data);

?? ?/* To determine what the adapter supports */
?? ?u32 (*functionality) (struct i2c_adapter *);
};

????????master_xfer：I2C传输时序,传输i2c_msg
????????master_xfer_atomic：同上,用于访问电源管理芯片
????????smbus_xfer：实现SMBus传输
????????smbus_xfer_atomic：用来访问电源管理芯片
????????functionality：返回flags(I2C_FUNC_*)
????????用于i2c通信方法描述

struct i2c_client {
?? ?unsigned short flags;?? ??? ?/* div., see below?? ??? ?*/
?? ?unsigned short addr;?? ??? ?/* chip address - NOTE: 7bit?? ?*/
?? ??? ??? ??? ??? ?/* addresses are stored in the?? ?*/
?? ??? ??? ??? ??? ?/* _LOWER_ 7 bits?? ??? ?*/
?? ?char name[I2C_NAME_SIZE];
?? ?struct i2c_adapter *adapter;?? ?/* the adapter we sit on?? ?*/
?? ?struct i2c_driver *driver;?? ?/* and our access routines?? ?*/
?? ?struct device dev;?? ??? ?/* the device structure?? ??? ?*/
?? ?int irq;?? ??? ??? ?/* irq issued by device?? ??? ?*/
?? ?struct list_head detected;
};

????????unsigned short flags;i2c设备特性标志位
????????unsigned short addr;i2c设备地址
????????char name[I2C_NAME_SIZE];i2c设备名
????????struct i2c_adapter *adapter;与次设备匹配成功的适配器
????????struct i2c_driver *driver;与次设备匹配成功的设备驱动
????????struct device dev;i2c设备
????????int irq;次设备中断引脚
? ? ? ? struct list_head detected;挂接到匹配成功的i2c_driver链表头上?
????????用于i2c次设备描述

struct i2c_driver {
?? ?unsigned int class;

?? ?/* Notifies the driver that a new bus has appeared or is about to be
?? ? * removed. You should avoid using this if you can, it will probably
?? ? * be removed in a near future.
?? ? */
?? ?int (*attach_adapter)(struct i2c_adapter *);
?? ?int (*detach_adapter)(struct i2c_adapter *);

?? ?/* Standard driver model interfaces */
?? ?int (*probe)(struct i2c_client *, const struct i2c_device_id *);
?? ?int (*remove)(struct i2c_client *);

?? ?/* driver model interfaces that don't relate to enumeration ?*/
?? ?void (*shutdown)(struct i2c_client *);
?? ?int (*suspend)(struct i2c_client *, pm_message_t mesg);
?? ?int (*resume)(struct i2c_client *);

?? ?/* Alert callback, for example for the SMBus alert protocol.
?? ? * The format and meaning of the data value depends on the protocol.
?? ? * For the SMBus alert protocol, there is a single bit of data passed
?? ? * as the alert response's low bit ("event flag").
?? ? */
?? ?void (*alert)(struct i2c_client *, unsigned int data);

?? ?/* a ioctl like command that can be used to perform specific functions
?? ? * with the device.
?? ? */
?? ?int (*command)(struct i2c_client *client, unsigned int cmd, void *arg);

?? ?struct device_driver driver;
?? ?const struct i2c_device_id *id_table;

?? ?/* Device detection callback for automatic device creation */
?? ?int (*detect)(struct i2c_client *, struct i2c_board_info *);
?? ?const unsigned short *address_list;
?? ?struct list_head clients;
};

????????unsigned int class;i2c设备驱动所支持的i2c设备的类型
????????int (*attach_adapter)(struct i2c_adapter *);匹配适配器
????????int (*probe)(struct i2c_client *, const struct i2c_device_id *); 设备驱动层probe函数
????????int (*remove)(struct i2c_client *);设备驱动卸载函数
????????const struct i2c_device_id *id_table;设备驱动的id_table(匹配驱动) ??
????????const unsigned short *address_list;驱动支持设备的地址数组
????????struct list_head clients;挂接与i2c_driver匹配成功的i2c_client(设备)
????????用于描述设备驱动

struct i2c_board_info {
?? ?char?? ??? ?type[I2C_NAME_SIZE];
?? ?unsigned short?? ?flags;
?? ?unsigned short?? ?addr;
?? ?void?? ??? ?*platform_data;
?? ?struct dev_archdata?? ?*archdata;
#ifdef CONFIG_OF
?? ?struct device_node *of_node;
#endif
?? ?int?? ??? ?irq;
};

????????char ?type[I2C_NAME_SIZE];i2c设备名字(i2c_client.name)
????????unsigned short ? ?flags;i2c_client.flags
????????unsigned short ? ?addr;i2c_client.addr
????????void ?*platform_data;i2c_client.dev.platform_data
????????struct dev_archdata ? ?*archdata;i2c_client.dev.archdata
????????int ?irq;i2c_client.irq
????????描述设备信息结构体

struct i2c_msg {
? ? __u16 addr; ? ? ? ? ? /*次设备地址 */
? ? __u16 flags; ? ? ? ? ?/* 标志位*/
#define I2C_M_TEN ? ? ? ? ? 0x0010 ? ?/* 设置设备地址是10bit */
#define I2C_M_RD ? ? ? ? ? ?0x0001 ? ?/* 设置i2c控制器为接收方,否则为发送方 */
#define I2C_M_NOSTART ? ? ? 0x4000 ? ?
#define I2C_M_REV_DIR_ADDR ?0x2000 ? ?/* 设置将读写标志位反转 */
#define I2C_M_IGNORE_NAK ? ?0x1000 ? ?/* 设置i2c_msg忽略I2C器件的ack和nack信号 */
#define I2C_M_NO_RD_ACK ? ? 0x0800 ? ?/* 设置读操作中主机不用ACK */
#define I2C_M_RECV_LEN ? ? ?0x0400 ? ?
? ? __u16 len; ? ? ? ? ? ? ? ? ? ? ? ?/* 数据长度 */
? ? __u8 *buf; ? ? ? ? ? ? ? ? ? ? ? ?/* 数据缓冲区指针 */
};

i2c CORE

postcore_initcall(i2c_init);
module_exit(i2c_exit);

static int __init i2c_init(void)
{
?? ?int retval;

?? ?retval = bus_register(&i2c_bus_type);
?? ?if (retval)
?? ??? ?return retval;
#ifdef CONFIG_I2C_COMPAT
?? ?i2c_adapter_compat_class = class_compat_register("i2c-adapter");
?? ?if (!i2c_adapter_compat_class) {
?? ??? ?retval = -ENOMEM;
?? ??? ?goto bus_err;
?? ?}
#endif
?? ?retval = i2c_add_driver(&dummy_driver);
?? ?if (retval)
?? ??? ?goto class_err;
?? ?return 0;

class_err:
#ifdef CONFIG_I2C_COMPAT
?? ?class_compat_unregister(i2c_adapter_compat_class);
bus_err:
#endif
?? ?bus_unregister(&i2c_bus_type);
?? ?return retval;
}

struct bus_type i2c_bus_type = {
?? ?.name?? ??? ?= "i2c",
?? ?.match?? ??? ?= i2c_device_match,
?? ?.probe?? ??? ?= i2c_device_probe,
?? ?.remove?? ??? ?= i2c_device_remove,
?? ?.shutdown?? ?= i2c_device_shutdown,
?? ?.pm?? ??? ?= &i2c_device_pm_ops,
};

static int i2c_device_match(struct device *dev, struct device_driver *drv)
{
?? ?struct i2c_client?? ?*client = i2c_verify_client(dev);
?? ?struct i2c_driver?? ?*driver;

?? ?if (!client)
?? ??? ?return 0;

?? ?driver = to_i2c_driver(drv);
?? ?/* match on an id table if there is one */
?? ?if (driver->id_table)
?? ??? ?return i2c_match_id(driver->id_table, client) != NULL;

?? ?return 0;
}

static int i2c_device_probe(struct device *dev)
{
?? ?struct i2c_client?? ?*client = i2c_verify_client(dev);
?? ?struct i2c_driver?? ?*driver;
?? ?int status;

?? ?if (!client)
?? ??? ?return 0;

?? ?driver = to_i2c_driver(dev->driver);
?? ?if (!driver->probe || !driver->id_table)
?? ??? ?return -ENODEV;
?? ?client->driver = driver;
?? ?if (!device_can_wakeup(&client->dev))
?? ??? ?device_init_wakeup(&client->dev,
?? ??? ??? ??? ??? ?client->flags & I2C_CLIENT_WAKE);
?? ?dev_dbg(dev, "probe\n");

?? ?status = driver->probe(client, i2c_match_id(driver->id_table, client));
?? ?if (status) {
?? ??? ?client->driver = NULL;
?? ??? ?i2c_set_clientdata(client, NULL);
?? ?}
?? ?return status;
}

????????i2c_match_id通过设备与设备驱动名字和i2c_device_id依次匹配,总线层的probe为设备client层的probe

注册接口
int i2c_add_adapter(struct i2c_adapter *adapter);
int i2c_add_numbered_adapter(struct i2c_adapter *adap);
注册adapter,都调用i2c_register_adapter,i2c_add_adapter自动分配适配器编号,i2c_add_numbered_adapter指定编号
static inline int i2c_add_driver(struct i2c_driver *driver);注册driver
struct i2c_client *i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info);注册client

static int i2c_register_adapter(struct i2c_adapter *adap)
{
?? ?int res = 0, dummy;

?? ?/* Can't register until after driver model init */
?? ?if (unlikely(WARN_ON(!i2c_bus_type.p))) {
?? ??? ?res = -EAGAIN;
?? ??? ?goto out_list;
?? ?}

?? ?rt_mutex_init(&adap->bus_lock);
?? ?INIT_LIST_HEAD(&adap->userspace_clients);

?? ?/* Set default timeout to 1 second if not already set */
?? ?if (adap->timeout == 0)
?? ??? ?adap->timeout = HZ;

?? ?dev_set_name(&adap->dev, "i2c-%d", adap->nr);
?? ?adap->dev.bus = &i2c_bus_type;
?? ?adap->dev.type = &i2c_adapter_type;
?? ?res = device_register(&adap->dev);
?? ?if (res)
?? ??? ?goto out_list;

?? ?dev_dbg(&adap->dev, "adapter [%s] registered\n", adap->name);

#ifdef CONFIG_I2C_COMPAT
?? ?res = class_compat_create_link(i2c_adapter_compat_class, &adap->dev,
?? ??? ??? ??? ? ? ? ? adap->dev.parent);
?? ?if (res)
?? ??? ?dev_warn(&adap->dev,
?? ??? ??? ? "Failed to create compatibility class link\n");
#endif

?? ?/* create pre-declared device nodes */
?? ?if (adap->nr < __i2c_first_dynamic_bus_num)
?? ??? ?i2c_scan_static_board_info(adap);

?? ?/* Notify drivers */
?? ?mutex_lock(&core_lock);
?? ?dummy = bus_for_each_drv(&i2c_bus_type, NULL, adap,
?? ??? ??? ??? ? __process_new_adapter);
?? ?mutex_unlock(&core_lock);

?? ?return 0;

out_list:
?? ?mutex_lock(&core_lock);
?? ?idr_remove(&i2c_adapter_idr, adap->nr);
?? ?mutex_unlock(&core_lock);
?? ?return res;
}

static void i2c_scan_static_board_info(struct i2c_adapter *adapter)
{
?? ?struct i2c_devinfo?? ?*devinfo;

?? ?down_read(&__i2c_board_lock);
?? ?list_for_each_entry(devinfo, &__i2c_board_list, list) {
?? ??? ?if (devinfo->busnum == adapter->nr
?? ??? ??? ??? ?&& !i2c_new_device(adapter,
?? ??? ??? ??? ??? ??? ?&devinfo->board_info))
?? ??? ??? ?dev_err(&adapter->dev,
?? ??? ??? ??? ?"Can't create device at 0x%02x\n",
?? ??? ??? ??? ?devinfo->board_info.addr);
?? ?}
?? ?up_read(&__i2c_board_lock);
}

int i2c_register_driver(struct module *owner, struct i2c_driver *driver)
{
?? ?int res;

?? ?/* Can't register until after driver model init */
?? ?if (unlikely(WARN_ON(!i2c_bus_type.p)))
?? ??? ?return -EAGAIN;

?? ?/* add the driver to the list of i2c drivers in the driver core */
?? ?driver->driver.owner = owner;
?? ?driver->driver.bus = &i2c_bus_type;

?? ?/* When registration returns, the driver core
?? ? * will have called probe() for all matching-but-unbound devices.
?? ? */
?? ?res = driver_register(&driver->driver);
?? ?if (res)
?? ??? ?return res;

?? ?pr_debug("i2c-core: driver [%s] registered\n", driver->driver.name);

?? ?INIT_LIST_HEAD(&driver->clients);
?? ?/* Walk the adapters that are already present */
?? ?mutex_lock(&core_lock);
?? ?bus_for_each_dev(&i2c_bus_type, NULL, driver, __process_new_driver);
?? ?mutex_unlock(&core_lock);

?? ?return 0;
}

?????????i2c_scan_static_board_info(adap);用于注册设备
????????遍历 __i2c_board_list上的i2c_devinfo结构体,比较i2c_devinfo->busnum与适配的编号,匹配则调用i2c_new_device注册
????????i2c_new_device是在系统启动时在smdkc110_machine_init注册i2c次设备
????????smdkc110_machine_init-->platform_add_devices-->s3c_i2c1_set_platdata-->i2c_register_board_info

i2c driver

subsys_initcall(i2c_adap_s3c_init);

static int __init i2c_adap_s3c_init(void)
{
?? ?return platform_driver_register(&s3c24xx_i2c_driver);
}

MODULE_DEVICE_TABLE(platform, s3c24xx_driver_ids);

static struct platform_driver s3c24xx_i2c_driver = {
?? ?.probe?? ??? ?= s3c24xx_i2c_probe,
?? ?.remove?? ??? ?= s3c24xx_i2c_remove,
?? ?.id_table?? ?= s3c24xx_driver_ids,
?? ?.driver?? ??? ?= {
?? ??? ?.owner?? ?= THIS_MODULE,
?? ??? ?.name?? ?= "s3c-i2c",
?? ??? ?.pm?? ?= S3C24XX_DEV_PM_OPS,
?? ?},
};

static int s3c24xx_i2c_probe(struct platform_device *pdev)
{
? ? struct s3c24xx_i2c *i2c; ? ? ? ? ? ? ? // ? 次结构体是三星对本SoC中的i2c控制器的一个描述，是一个用来在多文件中进行数据传递的全局结构体
? ? struct s3c2410_platform_i2c *pdata; ? ?// ? 此结构体用来表示平台设备的私有数据
? ? struct resource *res;
? ? int ret;
?
? ? pdata = pdev->dev.platform_data; ? ? ? // ?获取到平台设备层中的平台数据
? ? if (!pdata) {
? ? ? ? dev_err(&pdev->dev, "no platform data\n");
? ? ? ? return -EINVAL;
? ? }
?
? ? i2c = kzalloc(sizeof(struct s3c24xx_i2c), GFP_KERNEL); // ?给s3c24xx_i2c类型指针申请分配内存空间
? ? if (!i2c) {
? ? ? ? dev_err(&pdev->dev, "no memory for state\n");
? ? ? ? return -ENOMEM;
? ? }
?
// ? 以下主要是对s3c24xx_i2c 结构体中的i2c_adapter变量的一个填充
? ? strlcpy(i2c->adap.name, "s3c2410-i2c", sizeof(i2c->adap.name)); // ?设置适配器的名字 ? ?s3c2410-i2c
? ? i2c->adap.owner ? = THIS_MODULE;
? ? i2c->adap.algo ? ?= &s3c24xx_i2c_algorithm; ? ? ? ? ? ? ? ? ? ? // ?通信算法
? ? i2c->adap.retries = 2;
? ? i2c->adap.class ? = I2C_CLASS_HWMON | I2C_CLASS_SPD; ? ? ? ? ? ?// ?该适配器所支持的次设备类有哪些
? ? i2c->tx_setup ? ? = 50;
?
? ? spin_lock_init(&i2c->lock); ? ? ? // ?初始化互斥锁
? ? init_waitqueue_head(&i2c->wait); ?// ?初始化工作队列
?
? ? /* find the clock and enable it */
?
? ? i2c->dev = &pdev->dev; ? ? ? ? ? ?// ?通过s3c24xx_i2c->dev 指针指向平台设备的device结构体
? ? i2c->clk = clk_get(&pdev->dev, "i2c");
?
? ? if (IS_ERR(i2c->clk)) {
? ? ? ? dev_err(&pdev->dev, "cannot get clock\n");
? ? ? ? ret = -ENOENT;
? ? ? ? goto err_noclk;
? ? }
?
? ? dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);
?
? ? clk_enable(i2c->clk); ? ? ? ? ? ? // ?使能时钟
?
? ? /* map the registers */
?
? ? res = platform_get_resource(pdev, IORESOURCE_MEM, 0); ?// ?获取平台设备资源
? ? if (res == NULL) {
? ? ? ? dev_err(&pdev->dev, "cannot find IO resource\n");
? ? ? ? ret = -ENOENT;
? ? ? ? goto err_clk;
? ? }
?
? ? i2c->ioarea = request_mem_region(res->start, resource_size(res), // ?物理地址到虚拟地址的映射请求
? ? ? ? ? ? ? ? ? ? ?pdev->name);
?
? ? if (i2c->ioarea == NULL) {
? ? ? ? dev_err(&pdev->dev, "cannot request IO\n");
? ? ? ? ret = -ENXIO;
? ? ? ? goto err_clk;
? ? }
?
? ? i2c->regs = ioremap(res->start, resource_size(res)); ? ?// ?地址映射
?
? ? if (i2c->regs == NULL) {
? ? ? ? dev_err(&pdev->dev, "cannot map IO\n");
? ? ? ? ret = -ENXIO;
? ? ? ? goto err_ioarea;
? ? }
?
? ? dev_dbg(&pdev->dev, "registers %p (%p, %p)\n",
? ? ? ? i2c->regs, i2c->ioarea, res);
?
? ? /* setup info block for the i2c core */
?
? ? i2c->adap.algo_data = i2c; ? ? ? ? ?// ?将s3c24xx_i2c 结构体变量作为s3c24xx_i2c中内置的i2c_adapter适配器中的私有数据
? ? i2c->adap.dev.parent = &pdev->dev; ?// ?指定适配器设备的父设备是平台设备device : ? /sys/devices/platform/s3c2410-i2cn这个目录下
?
? ? /* initialise the i2c controller */
?
? ? ret = s3c24xx_i2c_init(i2c); ? ? ? ?// ?i2c控制器(适配器) ? ?寄存器相关的配置
? ? if (ret != 0)
? ? ? ? goto err_iomap;
?
? ? /* find the IRQ for this unit (note, this relies on the init call to
? ? ?* ensure no current IRQs pending
? ? ?*/
? ? i2c->irq = ret = platform_get_irq(pdev, 0); // ?获取平台设备中的i2c中断号(这个中断是I2C控制器产生的中断)
? ? if (ret <= 0) {
? ? ? ? dev_err(&pdev->dev, "cannot find IRQ\n");
? ? ? ? goto err_iomap;
? ? }
?
? ? ret = request_irq(i2c->irq, s3c24xx_i2c_irq, IRQF_DISABLED, ?// ?申请中断
? ? ? ? ? ? ? dev_name(&pdev->dev), i2c);
?
? ? if (ret != 0) {
? ? ? ? dev_err(&pdev->dev, "cannot claim IRQ %d\n", i2c->irq);
? ? ? ? goto err_iomap;
? ? }
?
? ? ret = s3c24xx_i2c_register_cpufreq(i2c); ? // ?这个不清楚
? ? if (ret < 0) {
? ? ? ? dev_err(&pdev->dev, "failed to register cpufreq notifier\n");
? ? ? ? goto err_irq;
? ? }
?
? ? /* Note, previous versions of the driver used i2c_add_adapter()
? ? ?* to add the bus at any number. We now pass the bus number via
? ? ?* the platform data, so if unset it will now default to always
? ? ?* being bus 0.
? ? ?*/
? ? i2c->adap.nr = pdata->bus_num; ? ? ? ? ? ? ?// ?确定i2c主机(适配器)的编号
?
? ? ret = i2c_add_numbered_adapter(&i2c->adap); // ?向i2c核心注册i2c适配器 ?/sys/devices/platform/s3c2410-i2cn/s3c2410-i2c ? 因为在函数内会将 i2c-%d作为适配器的名字
? ? if (ret < 0) {
? ? ? ? dev_err(&pdev->dev, "failed to add bus to i2c core\n");
? ? ? ? goto err_cpufreq;
? ? }
?
? ? platform_set_drvdata(pdev, i2c); ? // ?将s3c24xx_i2c变量作为平台设备私有数据中的设备驱动私有数据 ?dev->p->driver_data
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// ?因为这个变量还会在本文件中其他函数中会用到了?
? ? clk_disable(i2c->clk);
?
? ? dev_info(&pdev->dev, "%s: S3C I2C adapter\n", dev_name(&i2c->adap.dev));
? ? return 0;
?
?err_cpufreq:
? ? s3c24xx_i2c_deregister_cpufreq(i2c);
?
?err_irq:
? ? free_irq(i2c->irq, i2c);
?
?err_iomap:
? ? iounmap(i2c->regs);
?
?err_ioarea:
? ? release_resource(i2c->ioarea);
? ? kfree(i2c->ioarea);
?
?err_clk:
? ? clk_disable(i2c->clk);
? ? clk_put(i2c->clk);
?
?err_noclk:
? ? kfree(i2c);
? ? return ret;
}

i2c client

????????210使用I2C电容触摸屏(gslx680)

module_init(gsl_ts_init);
module_exit(gsl_ts_exit);

static int __init gsl_ts_init(void)
{
? ? int ret;
?? ?print_info("==gsl_ts_init==\n");
?? ?ret = i2c_add_driver(&gsl_ts_driver);
?? ?print_info("ret=%d\n",ret);
?? ?return ret;
}

static inline int i2c_add_driver(struct i2c_driver *driver)
{
?? ?return i2c_register_driver(THIS_MODULE, driver);
}

MODULE_DEVICE_TABLE(i2c, gsl_ts_id);

static struct i2c_driver gsl_ts_driver = {
?? ?.driver = {
?? ??? ?.name = GSLX680_I2C_NAME,
?? ??? ?.owner = THIS_MODULE,
?? ?},
#ifndef CONFIG_HAS_EARLYSUSPEND
?? ?.suspend?? ?= gsl_ts_suspend,
?? ?.resume?? ?= gsl_ts_resume,
#endif
?? ?.probe?? ??? ?= gsl_ts_probe,
?? ?.remove?? ??? ?= __devexit_p(gsl_ts_remove),
?? ?.id_table?? ?= gsl_ts_id,
};

#define GSLX680_I2C_NAME ?? ?"gslX680"
#define GSLX680_I2C_ADDR ?? ?0x40
#define IRQ_PORT?? ??? ??? ?IRQ_EINT(7)
#define GSL_DATA_REG?? ??? ?0x80
#define GSL_STATUS_REG?? ??? ?0xe0
#define GSL_PAGE_REG?? ??? ?0xf0

static int __devinit gsl_ts_probe(struct i2c_client *client,
? ? ? ? ? ? const struct i2c_device_id *id)
{
? ? struct gsl_ts *ts; ? ? ?// ?设备驱动层封装的一个全局结构体
? ? int rc;
?
? ? print_info("GSLX680 Enter %s\n", __func__);
? ? if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
? ? ? ? dev_err(&client->dev, "I2C functionality not supported\n");
? ? ? ? return -ENODEV;
? ? }
?
? ? ts = kzalloc(sizeof(*ts), GFP_KERNEL); ?// ?给 gsl_ts类型的指针申请分配内存
? ? if (!ts)
? ? ? ? return -ENOMEM;
? ? print_info("==kzalloc success=\n");
?
? ? ts->client = client; ? ? ? ? ? ? ? ? ? ?// ?通过gsl_ts->client指针去指向传进来的i2c次设备i2c_client
? ? i2c_set_clientdata(client, ts); ? ? ? ? // ?将gsl_ts作为i2c次设备的私有数据区中的设备驱动私有数据
? ? ts->device_id = id->driver_data;
?
? ? rc = gslX680_ts_init(client, ts); ? ? ? // ? 初始化操作
? ? if (rc < 0) {
? ? ? ? dev_err(&client->dev, "GSLX680 init failed\n");
? ? ? ? goto error_mutex_destroy;
? ? } ? ?
?
? ? gsl_client = client; ? ? ? // ?通过一个全局的i2c_client指针gsl_client去指向传进来的i2c次设备i2c_client
? ??
? ? gslX680_init(); ? ? ? ? ? ?// ?gslX680 触摸屏相关的gpio初始化操作
? ? init_chip(ts->client); ? ? // ?gslX680触摸屏芯片相关的初始化操作
? ? check_mem_data(ts->client);
? ??
? ? rc= ?request_irq(client->irq, gsl_ts_irq, IRQF_TRIGGER_RISING, client->name, ts); // ?申请中断，这个中断是接在SoC的一个外部中断引脚上的
? ? if (rc < 0) { ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // 当发生中断的时候表示有数据可以进行读取了，那么就会通知
? ? ? ? print_info( "gsl_probe: request irq failed\n"); ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? // ?I2C主机去去读数据?
? ? ? ? goto error_req_irq_fail;
? ? }
?
? ? /* create debug attribute */
? ? //rc = device_create_file(&ts->input->dev, &dev_attr_debug_enable);
?
#ifdef CONFIG_HAS_EARLYSUSPEND
? ? ts->early_suspend.level = EARLY_SUSPEND_LEVEL_BLANK_SCREEN + 1;
? ? //ts->early_suspend.level = EARLY_SUSPEND_LEVEL_DISABLE_FB + 1;
? ? ts->early_suspend.suspend = gsl_ts_early_suspend;
? ? ts->early_suspend.resume = gsl_ts_late_resume;
? ? register_early_suspend(&ts->early_suspend);
#endif
?
?
#ifdef GSL_MONITOR
? ? print_info( "gsl_ts_probe () : queue gsl_monitor_workqueue\n");
?
? ? INIT_DELAYED_WORK(&gsl_monitor_work, gsl_monitor_worker);
? ? gsl_monitor_workqueue = create_singlethread_workqueue("gsl_monitor_workqueue");
? ? queue_delayed_work(gsl_monitor_workqueue, &gsl_monitor_work, 1000);
#endif
?
? ? print_info("[GSLX680] End %s\n", __func__);
?
? ? return 0;
?
//exit_set_irq_mode: ? ?
error_req_irq_fail:
? ? free_irq(ts->irq, ts); ? ?
?
error_mutex_destroy:
? ? input_free_device(ts->input);
? ? kfree(ts);
? ? return rc;
}

static int gslX680_ts_init(struct i2c_client *client, struct gsl_ts *ts)
{
? ? struct input_dev *input_device; ? ? ? ? ? ?// ? 定义一个 input_dev 结构体指针
? ? int rc = 0;
? ??
? ? printk("[GSLX680] Enter %s\n", __func__);
?
? ? ts->dd = &devices[ts->device_id];
?
? ? if (ts->device_id == 0) {
? ? ? ? ts->dd->data_size = MAX_FINGERS * ts->dd->touch_bytes + ts->dd->touch_meta_data;
? ? ? ? ts->dd->touch_index = 0;
? ? }
?
? ? ts->touch_data = kzalloc(ts->dd->data_size, GFP_KERNEL);
? ? if (!ts->touch_data) {
? ? ? ? pr_err("%s: Unable to allocate memory\n", __func__);
? ? ? ? return -ENOMEM;
? ? }
?
? ? input_device = input_allocate_device(); ? ?// ?给input_device指针申请分配内存
? ? if (!input_device) {
? ? ? ? rc = -ENOMEM;
? ? ? ? goto error_alloc_dev;
? ? }
?
? ? ts->input = input_device; ? ? ? ? ? ? ? ? ?// ?通过gsl_ts->input指针去指向input输入设备
? ? input_device->name = GSLX680_I2C_NAME; ? ? // ?设置input设备的名字
? ? input_device->id.bustype = BUS_I2C; ? ? ? ?// ?设置input设备的总线类型
? ? input_device->dev.parent = &client->dev; ? // ?设置input设备的父设备: ? /sys/devices/platform/s3c2410-i2cn/i2c-%d/%d-%04x
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// ?但是通过后面的分析可知，最终不是这个父设备
? ? input_set_drvdata(input_device, ts); ? ? ? // ?将gsl_ts结构体作为input设备的私有数据区中的设备驱动数据
?
// ? 以下是对input_dev 输入设备的一些设置 ?设置input设备可以上报的事件类型
? ? set_bit(EV_ABS, input_device->evbit);
? ? set_bit(BTN_TOUCH, input_device->keybit);
? ? set_bit(EV_ABS, input_device->evbit);
? ? set_bit(EV_KEY, input_device->evbit);
? ? input_set_abs_params(input_device, ABS_X, 0, SCREEN_MAX_X, 0, 0);
? ? input_set_abs_params(input_device, ABS_Y, 0, SCREEN_MAX_Y, 0, 0);
? ? input_set_abs_params(input_device, ABS_PRESSURE, 0, 1, 0, 0);
#ifdef HAVE_TOUCH_KEY
? ? input_device->evbit[0] = BIT_MASK(EV_KEY);
? ? //input_device->evbit[0] = BIT_MASK(EV_SYN) | BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
? ? for (i = 0; i < MAX_KEY_NUM; i++)
? ? ? ? set_bit(key_array[i], input_device->keybit);
#endif
? ??
? ? client->irq = IRQ_PORT; ? ? ? ? ? ? ? // ?触摸屏使用到的中断号
? ? ts->irq = client->irq; ? ? ? ? ? ? ? ?// ?
?
? ? ts->wq = create_singlethread_workqueue("kworkqueue_ts");
? ? if (!ts->wq) {
? ? ? ? dev_err(&client->dev, "Could not create workqueue\n");
? ? ? ? goto error_wq_create;
? ? }
? ? flush_workqueue(ts->wq); ? ?
?
? ? INIT_WORK(&ts->work, gslX680_ts_worker); ? // ?初始化工作队列 ?当发生中断的时候在在中断处理函数中就会调用这个工作队列
? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?// ?作为中断的下半部
? ? rc = input_register_device(input_device); ?// ? 注册input设备
? ? if (rc)
? ? ? ? goto error_unreg_device;
?
? ? return 0;
?
error_unreg_device:
? ? destroy_workqueue(ts->wq);
error_wq_create:
? ? input_free_device(input_device);
error_alloc_dev:
? ? kfree(ts->touch_data);
? ? return rc;
}

????????中断上半部是probe函数绑定gsl_ts_irq,下半部gslX680_ts_worker
????????gslX680_ts_worker-->gsl_ts_read-->i2c_master_recv-->i2c_transfer-->adap->algo->master_xfer(adap, msgs, num) ? ? ?
????????gsl_ts_write-->i2c_master_send-->i2c_transfer-->adap->algo->master_xfer(adap, msgs, num)
????????工作流程：触摸屏按下并-->触摸屏IC完成AD转换-->中断信号到I2C控制器-->I2C设备驱动层中断函数-->核心层调用I2C总线驱动层的通信算法到缓冲区

中断
????????中断上下文不能和用户空间数据交互,不能交出CPU(不能休眠、不能schedule)
????????中断上文中可处理其他更紧急事务
????????中断下文处理策略:tasklet(小任务),workqueue(工作队列)
????????任务急切且少在tasklet执行,所不急迫且任务多在workqueue中执行

demo1:

? ? ? ? 使用中断上下文(tasklet,workqueue)实现按键捕获

? ? ? ? 写应用程序捕获触摸屏反馈信息

button_tasklet_workqueue-x210.c

#include <linux/input.h> 
#include <linux/module.h> 
#include <linux/init.h>
#include <asm/irq.h> 
#include <asm/io.h>
#include <mach/irqs.h>
#include <linux/interrupt.h>
#include <linux/gpio.h>


#define BUTTON_IRQ      IRQ_EINT2

static struct input_dev *button_dev;

//void func(unsigned long data)
void func(struct work_struct *work)
{
        int flag;

        printk("bottom half\n");

        s3c_gpio_cfgpin(S5PV210_GPH0(2), S3C_GPIO_SFN(0x0));            // input模式
        flag = gpio_get_value(S5PV210_GPH0(2));
        s3c_gpio_cfgpin(S5PV210_GPH0(2), S3C_GPIO_SFN(0x0f));           // eint2模式

        input_report_key(button_dev, KEY_LEFT, !flag);
        input_sync(button_dev);
}

//DECLARE_TASKLET(button_tasklet, func, 0);
DECLARE_WORK(button_work, func);

static irqreturn_t button_interrupt(int irq, void *dummy) 
{ 
        printk("top half\n");

        //tasklet_schedule(&button_tasklet);
        schedule_work(&button_work);

        return IRQ_HANDLED; 
}

static int __init button_init(void) 
{ 
        int error;

        error = gpio_request(S5PV210_GPH0(2), "GPH0_2");
        if(error)
                printk("key-s5pv210: request gpio GPH0(2) fail");
        s3c_gpio_cfgpin(S5PV210_GPH0(2), S3C_GPIO_SFN(0x0f));           // eint2模式

        if (request_irq(BUTTON_IRQ, button_interrupt, IRQF_TRIGGER_FALLING | IRQF_TRIGGER_RISING, "button-x210", NULL)) 
        { 
                printk(KERN_ERR "key-s5pv210.c: Can't allocate irq %d\n", BUTTON_IRQ);
                goto err_free_gpio;
        }
        button_dev = input_allocate_device();
        if (!button_dev) 
        { 
                printk(KERN_ERR "key-s5pv210.c: Not enough memory\n");
                error = -ENOMEM;
                goto err_free_irq; 
        }

        button_dev->evbit[0] = BIT_MASK(EV_KEY);
        button_dev->keybit[BIT_WORD(KEY_LEFT)] = BIT_MASK(KEY_LEFT);

        error = input_register_device(button_dev);
        if (error) 
        { 
                printk(KERN_ERR "key-s5pv210.c: Failed to register device\n");
                goto err_free_dev; 
        }
        return 0;

err_free_dev:
        input_free_device(button_dev);
err_free_irq:
        free_irq(BUTTON_IRQ, button_interrupt);
        return error; 
err_free_gpio:
                gpio_free(S5PV210_GPH0(2));
        return error;
}

static void __exit button_exit(void) 
{ 
        input_unregister_device(button_dev); 
        input_free_device(button_dev);
        free_irq(BUTTON_IRQ, NULL);
        gpio_free(S5PV210_GPH0(2));
}

module_init(button_init); 
module_exit(button_exit); 
MODULE_LICENSE("GPL");
MODULE_AUTHOR("cxb");
MODULE_DESCRIPTION("button  module");
MODULE_ALIAS("button");

button.c?

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/input.h>
#include <string.h>
 
#define X210_KEY        "/dev/input/event2"
 
 
int main(void)
{
        int fd = -1, ret = -1;
        struct input_event ev;

        fd = open(X210_KEY, O_RDONLY);
        if (fd < 0)
        {
                perror("open");
                return -1;
        }

        while (1)
        {
                memset(&ev, 0, sizeof(struct input_event));
                ret = read(fd, &ev, sizeof(struct input_event));
                if (ret != sizeof(struct input_event))
                {
                        perror("read");
                        close(fd);
                        return -1;
                }

                printf("-------------------------\n");
                printf("type: %hd\n", ev.type);
                printf("code: %hd\n", ev.code);
                printf("value: %d\n", ev.value);
                printf("\n");
        }

        close(fd);

        return 0;
}

touchscreen.c?

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/input.h>
#include <string.h>
 
#define X210_TOUCHSCREEN        "/dev/input/event1"
 
 
int main(void)
{
        int fd = -1, ret = -1;
        struct input_event ev;

        fd = open(X210_TOUCHSCREEN, O_RDONLY);
        if (fd < 0)
        {
                perror("open");
                return -1;
        }

        while (1)
        {
                memset(&ev, 0, sizeof(struct input_event));
                ret = read(fd, &ev, sizeof(struct input_event));
                if (ret != sizeof(struct input_event))
                {
                        perror("read");
                        close(fd);
                        return -1;
                }

                printf("-------------------------\n");
                printf("type: %hd\n", ev.type);
                printf("code: %hd\n", ev.code);
                printf("value: %d\n", ev.value);
                printf("\n");
        }

        close(fd);

        return 0;
}

Makefile?

KERN_DIR = /root/kernel
 
obj-m   += button_tasklet_workqueue-x210.o
 
all:
         make -C $(KERN_DIR) M=`pwd` modules 
         arm-linux-gcc touchscreen.c -o touchscreen
         arm-linux-gcc button.c -o button
cp:
         cp *.ko touchscreen button /root/rootfs/driver -f
 
.PHONY: clean
clean:
         make -C $(KERN_DIR) M=`pwd` modules clean
         rm -rf touchscreen button

?结果如图所示：

button

touch screen?