s3c2440串口驱动笔记【已修改】

终端设备驱动:
终端设备分类:串行端口终端(/dev/ttySn), 伪端口(/dev/pty), 控制台终端(/dev/ttyn, /dev/console) 。
终端设备驱动结构:包含tty核心,tty线路规程(以特殊的方式格式化从一个用户或硬件收到到数据,ppp或bluetooth),tty驱动。
tty设备发送数据流程:tty核心从用户获取数据---->tty线程规程驱动----->tty驱动----->硬件。接收数据,相反。
 

Linux系统的串口驱动与一般字符设备并一样,它采用层次化的架构,从而看做是一个串行系统来实现。

(1)      关注UART或其他底层串行硬件特征的底层驱动程序。

(2)      和底层驱动程序接口的TTY驱动程序。

(3)      加工用于和TTY驱动程序交换数据的线路规程。

下图描述了串行系统间的层次结构关系(s3c2440串口实现例),可以概括为:用户应用层 --> 线路规划层 --> TTY层 --> 底层驱动层 --> 物理硬件层

 

线路规程和TTY驱动程序是与硬件平台无关的,Linux源码中已经提供了实现,所以对于具体的平台,我们只需实现底层驱动程序即可,这也是我们最关心的。在s3c2440a中,主要由dirivers/serial/下的s3c2440.c和samsung.c实现。

Uart驱动程序主要围绕三个关键的数据结构展开(include/linux/serial_core.h中定义):

UART特定的驱动程序结构定义:struct uart_driver s3c24xx_uart_drv;

UART端口结构定义: struct uart_port s3c24xx_serial_ops;

UART相关操作函数结构定义: struct uart_ops s3c24xx_serial_ops;

 

tty设备驱动的主体工作是填充tty_driver结构体:
struct tty_driver {
int magic; /* magic number for this structure ,在alloc_tty_driver()中被初始化*/
struct kref kref; /* Reference management */
struct cdev cdev; //对应到字符设备cdev
struct module *owner;
const char *driver_name;
const char *name; //设备名
int name_base; /* offset of printed name */
int major; /* major device number */
int minor_start; /* start of minor device number */
int minor_num; /* number of *possible* devices */
int num; /* number of devices allocated */
short type; /* type of tty driver */
short subtype; /* subtype of tty driver */
struct ktermios init_termios; /* Initial termios */
int flags; /* tty driver flags */
struct proc_dir_entry *proc_entry; /* /proc fs entry */
struct tty_driver *other; /* only used for the PTY driver */

/*
* Pointer to the tty data structures
*/
struct tty_struct **ttys;
struct ktermios **termios;
struct ktermios **termios_locked;
void *driver_state;

/*
* Driver methods
*/

const struct tty_operations *ops;
struct list_head tty_drivers;
};

tty_operations结构体:
struct tty_operations {
struct tty_struct * (*lookup)(struct tty_driver *driver,
struct inode *inode, int idx);
int  (*install)(struct tty_driver *driver, struct tty_struct *tty);
void (*remove)(struct tty_driver *driver, struct tty_struct *tty);
int  (*open)(struct tty_struct * tty, struct file * filp);
void (*close)(struct tty_struct * tty, struct file * filp);
void (*shutdown)(struct tty_struct *tty);
void (*cleanup)(struct tty_struct *tty);
int  (*write)(struct tty_struct * tty,
     const unsigned char *buf, int count);
int  (*put_char)(struct tty_struct *tty, unsigned char ch); //单个字节写函数
void (*flush_chars)(struct tty_struct *tty); //刷新数据到硬件
int  (*write_room)(struct tty_struct *tty); //指示有多少缓冲区空闲
int  (*chars_in_buffer)(struct tty_struct *tty); //指示缓冲区到长度
int  (*ioctl)(struct tty_struct *tty, struct file * file, //
   unsigned int cmd, unsigned long arg);
long (*compat_ioctl)(struct tty_struct *tty, struct file * file,
    unsigned int cmd, unsigned long arg);
void (*set_termios)(struct tty_struct *tty, struct ktermios * old);
void (*throttle)(struct tty_struct * tty); //tty核心输入缓冲满时调用
void (*unthrottle)(struct tty_struct * tty); //tty核心输入缓冲已被清空时调用
void (*stop)(struct tty_struct *tty); //停止tty驱动发数据给设备
void (*start)(struct tty_struct *tty); //恢复tty驱动发数据给设备
void (*hangup)(struct tty_struct *tty);
int (*break_ctl)(struct tty_struct *tty, int state);
void (*flush_buffer)(struct tty_struct *tty); //刷新缓冲区,丢弃剩下的数据
void (*set_ldisc)(struct tty_struct *tty);
void (*wait_until_sent)(struct tty_struct *tty, int timeout);
void (*send_xchar)(struct tty_struct *tty, char ch);
int (*tiocmget)(struct tty_struct *tty, struct file *file);
int (*tiocmset)(struct tty_struct *tty, struct file *file,
unsigned int set, unsigned int clear);
int (*resize)(struct tty_struct *tty, struct winsize *ws);
int (*set_termiox)(struct tty_struct *tty, struct termiox *tnew);
int (*get_icount)(struct tty_struct *tty,
struct serial_icounter_struct *icount);
#ifdef CONFIG_CONSOLE_POLL
int (*poll_init)(struct tty_driver *driver, int line, char *options);
int (*poll_get_char)(struct tty_driver *driver, int line);
void (*poll_put_char)(struct tty_driver *driver, int line, char ch);
#endif
const struct file_operations *proc_fops;
};
1.分配tty驱动:
struct tty_driver *alloc_tty_driver(int lines);line为要分配到设备数量。
2.注册tty驱动:
int tty_register_driver(struct tty_driver *driver);
3.注销tty驱动:
int tty_unregister_driver(struct tty_driver *driver);
4.注册tty设备:
void tty_register_device(struct tty_driver *driver, unsigned index, struct device *device);用于注册关联于tty_driver的设备。
5.注销tty设备:
void tty_unregister_device(struct tty_driver *driver, unsigned index);
6.设置tty驱动操作:
void tty_set_operations(struct tty_driver *driver, struct tty_operations *op);
终端设备驱动应该包含:
1.模块加载和卸载函数:完成注册和注销tty_driver, 初始化和释放终端设备对应的tty_driver结构体成员及硬件资源。
2.实现tty_operations结构体中的函数:open, close, write,tiocmget, tiocmset等。


tty线路设置:
改变tty设备的线路设置或获取当前线路设置的两种方式:
1.调用用户空间的termios库函数。
 int tcgetattr(int fd, struct termios *termios_p); //获取终端设备的操作模式
 int tcsetattr(int fd, int optional_actions, struct termios *termios_p); //设置终端设备的操作模式
 输入/输出波特率的获取和设置:
  speed_t cfgetospeed(struct termios *termios_p); //获得输出波特率
  speed_t cfgetispeed(struct termios *termios_p); //获得输入波特率
  
  int cfsetospeed(struct termios *termios_p, speed_t speed); //设置输出波特率
  int cfsetispeed(struct termios *termios_p, speed_t speed); //设置输入波特率
线路控制函数:
  int tcdrain(int fd); //等待所有输出都被发送
  int tcflush(int fd, int queue_selector); //flush输入/输出缓存
  int tcflow(int fd, int action); //对输入和输出流进行控制
  int tcsendbreak(int fd, int duration); //发送break
2.对tty设备节点进行ioctl()调用
  termios库函数会被转化为对tty设备节点的ioctl()调用。



UART设备驱动:
linux内涵在serial_core.c文件中实现了UART设备的通用tty驱动层(串口核心层)。因此UART驱动的任务就变为实现serial_core.c中定义的一组uart_xxx接口。
串口核心层为串口设备驱动提供了3个结构体: uart_driver, uart_port, uart_ops。
struct uart_driver {
struct module *owner;
const char *driver_name;
const char *dev_name;
int major;
int minor;
int nr;
struct console *cons;

/*
* these are private; the low level driver should not
* touch these; they should be initialised to NULL
*/
struct uart_state *state;
struct tty_driver *tty_driver;
};
UART驱动注册/注销函数:
int uart_register_driver(struct uart_driver *drv);
void uart_unregister_driver(struct uart_driver *drv);
这两个函数的实现,包含了tty_register_driver()和tty_unregister_driver()。

struct uart_port {
spinlock_t lock; /* port lock */
unsigned long iobase; /* in/out[bwl] */IO端口基地址
unsigned char __iomem *membase; /* read/write[bwl] */IO内存基地址
unsigned int (*serial_in)(struct uart_port *, int);
void (*serial_out)(struct uart_port *, int, int);
unsigned int irq; /* irq number */
unsigned long irqflags; /* irq flags  */
unsigned int uartclk; /* base uart clock */
unsigned int fifosize; /* tx fifo size */
unsigned char x_char; /* xon/xoff char */
unsigned char regshift; /* reg offset shift */
unsigned char iotype; /* io access style */
unsigned char unused1;

#define UPIO_PORT (0)
#define UPIO_HUB6 (1)
#define UPIO_MEM (2)
#define UPIO_MEM32 (3)
#define UPIO_AU (4) /* Au1x00 type IO */
#define UPIO_TSI (5) /* Tsi108/109 type IO */
#define UPIO_DWAPB (6) /* DesignWare APB UART */
#define UPIO_RM9000 (7) /* RM9000 type IO */

unsigned int read_status_mask; /* driver specific */驱动特定的读状态掩码
unsigned int ignore_status_mask; /* driver specific */驱动特定的忽略状态掩码
struct uart_state *state; /* pointer to parent state */
struct uart_icount icount; /* statistics */

struct console *cons; /* struct console, if any */
#if defined(CONFIG_SERIAL_CORE_CONSOLE) || defined(SUPPORT_SYSRQ)
unsigned long sysrq; /* sysrq timeout */
#endif

upf_t flags;

#define UPF_FOURPORT ((__force upf_t) (1 << 1))
#define UPF_SAK ((__force upf_t) (1 << 2))
#define UPF_SPD_MASK ((__force upf_t) (0x1030))
#define UPF_SPD_HI ((__force upf_t) (0x0010))
#define UPF_SPD_VHI ((__force upf_t) (0x0020))
#define UPF_SPD_CUST ((__force upf_t) (0x0030))
#define UPF_SPD_SHI ((__force upf_t) (0x1000))
#define UPF_SPD_WARP ((__force upf_t) (0x1010))
#define UPF_SKIP_TEST ((__force upf_t) (1 << 6))
#define UPF_AUTO_IRQ ((__force upf_t) (1 << 7))
#define UPF_HARDPPS_CD ((__force upf_t) (1 << 11))
#define UPF_LOW_LATENCY ((__force upf_t) (1 << 13))
#define UPF_BUGGY_UART ((__force upf_t) (1 << 14))
#define UPF_NO_TXEN_TEST ((__force upf_t) (1 << 15))
#define UPF_MAGIC_MULTIPLIER ((__force upf_t) (1 << 16))
#define UPF_CONS_FLOW ((__force upf_t) (1 << 23))
#define UPF_SHARE_IRQ ((__force upf_t) (1 << 24))
/* The exact UART type is known and should not be probed.  */
#define UPF_FIXED_TYPE ((__force upf_t) (1 << 27))
#define UPF_BOOT_AUTOCONF ((__force upf_t) (1 << 28))
#define UPF_FIXED_PORT ((__force upf_t) (1 << 29))
#define UPF_DEAD ((__force upf_t) (1 << 30))
#define UPF_IOREMAP ((__force upf_t) (1 << 31))

#define UPF_CHANGE_MASK ((__force upf_t) (0x17fff))
#define UPF_USR_MASK ((__force upf_t) (UPF_SPD_MASK|UPF_LOW_LATENCY))

unsigned int mctrl; /* current modem ctrl settings */
unsigned int timeout; /* character-based timeout */
unsigned int type; /* port type */
const struct uart_ops *ops;
unsigned int custom_divisor;
unsigned int line; /* port index */
resource_size_t mapbase; /* for ioremap */
struct device *dev; /* parent device */
unsigned char hub6; /* this should be in the 8250 driver */
unsigned char suspended;
unsigned char unused[2];
void *private_data; /* generic platform data pointer */
};
uart_port用于描述一个UART端口到IO端口或IO内存地址,FIFO大小,端口类型等信息。
添加/删除端口函数:
int uart_add_one_port(struct uart_driver *drv, struct uart_port *port);
int uart_remove_one_port(struct uart_driver *drv, struct uart_port *port);


struct uart_ops {
unsigned int (*tx_empty)(struct uart_port *);
void (*set_mctrl)(struct uart_port *, unsigned int mctrl);
unsigned int (*get_mctrl)(struct uart_port *);
void (*stop_tx)(struct uart_port *);
void (*start_tx)(struct uart_port *);
void (*send_xchar)(struct uart_port *, char ch);
void (*stop_rx)(struct uart_port *);
void (*enable_ms)(struct uart_port *);
void (*break_ctl)(struct uart_port *, int ctl);
int (*startup)(struct uart_port *);
void (*shutdown)(struct uart_port *);
void (*flush_buffer)(struct uart_port *);
void (*set_termios)(struct uart_port *, struct ktermios *new,
      struct ktermios *old);
void (*set_ldisc)(struct uart_port *);
void (*pm)(struct uart_port *, unsigned int state,
     unsigned int oldstate);
int (*set_wake)(struct uart_port *, unsigned int state);

/*
* Return a string describing the type of the port
*/
const char *(*type)(struct uart_port *);

/*
* Release IO and memory resources used by the port.
* This includes iounmap if necessary.
*/
void (*release_port)(struct uart_port *);

/*
* Request IO and memory resources used by the port.
* This includes iomapping the port if necessary.
*/
int (*request_port)(struct uart_port *);
void (*config_port)(struct uart_port *, int);
int (*verify_port)(struct uart_port *, struct serial_struct *);
int (*ioctl)(struct uart_port *, unsigned int, unsigned long);
#ifdef CONFIG_CONSOLE_POLL
void (*poll_put_char)(struct uart_port *, unsigned char);
int (*poll_get_char)(struct uart_port *);
#endif
};
uart_ops定义了对UART的一系列操作,包括发送,接收及线路设置等。

使用串口核心层这个通用串口tty驱动层的接口后,一个串口驱动要完成的主要工作就简单很多了。


s3c2440的UART驱动注释:
/* linux/drivers/serial/s3c2440.c*/
#include
#include
#include
#include
#include
#include //串口核心层头文件
#include

#include
#include

#include
#include

#include "samsung.h"


static int s3c2440_serial_setsource(struct uart_port *port,
    struct s3c24xx_uart_clksrc *clk) //设置时钟
{
unsigned long ucon = rd_regl(port, S3C2410_UCON); // ucon 内存地址=(port)->membase + S3C2410_UCON

/* todo - proper fclk<>nonfclk switch. */

ucon &= ~S3C2440_UCON_CLKMASK; 

if (strcmp(clk->name, "uclk") == 0)
ucon |= S3C2440_UCON_UCLK;
else if (strcmp(clk->name, "pclk") == 0)
ucon |= S3C2440_UCON_PCLK;
else if (strcmp(clk->name, "fclk") == 0)
ucon |= S3C2440_UCON_FCLK;
else {
printk(KERN_ERR "unknown clock source %s\n", clk->name);
return -EINVAL;
}

wr_regl(port, S3C2410_UCON, ucon);
return 0;
}


static int s3c2440_serial_getsource(struct uart_port *port,
   struct s3c24xx_uart_clksrc *clk)//读取时钟设置
{
unsigned long ucon = rd_regl(port, S3C2410_UCON);
unsigned long ucon0, ucon1, ucon2;

switch (ucon & S3C2440_UCON_CLKMASK) {
case S3C2440_UCON_UCLK:
clk->divisor = 1;
clk->name = "uclk";
break;

case S3C2440_UCON_PCLK:
case S3C2440_UCON_PCLK2:
clk->divisor = 1;
clk->name = "pclk";
break;

case S3C2440_UCON_FCLK:
/* the fun of calculating the uart divisors on
* the s3c2440 */

ucon0 = __raw_readl(S3C24XX_VA_UART0 + S3C2410_UCON);
ucon1 = __raw_readl(S3C24XX_VA_UART1 + S3C2410_UCON);
ucon2 = __raw_readl(S3C24XX_VA_UART2 + S3C2410_UCON);

printk("ucons: %08lx, %08lx, %08lx\n", ucon0, ucon1, ucon2);

ucon0 &= S3C2440_UCON0_DIVMASK;
ucon1 &= S3C2440_UCON1_DIVMASK;
ucon2 &= S3C2440_UCON2_DIVMASK;

if (ucon0 != 0) {
clk->divisor = ucon0 >> S3C2440_UCON_DIVSHIFT;
clk->divisor += 6;
} else if (ucon1 != 0) {
clk->divisor = ucon1 >> S3C2440_UCON_DIVSHIFT;
clk->divisor += 21;
} else if (ucon2 != 0) {
clk->divisor = ucon2 >> S3C2440_UCON_DIVSHIFT;
clk->divisor += 36;
} else {
/* manual calims 44, seems to be 9 */
clk->divisor = 9;
}

clk->name = "fclk";
break;
}

return 0;
}

static int s3c2440_serial_resetport(struct uart_port *port,
   struct s3c2410_uartcfg *cfg)
{
unsigned long ucon = rd_regl(port, S3C2410_UCON);

dbg("s3c2440_serial_resetport: port=%p (%08lx), cfg=%p\n",
   port, port->mapbase, cfg);

/* ensure we don't change the clock settings... */

ucon &= (S3C2440_UCON0_DIVMASK | (3<<10));

wr_regl(port, S3C2410_UCON,  ucon | cfg->ucon);
wr_regl(port, S3C2410_ULCON, cfg->ulcon);

/* reset both fifos */

wr_regl(port, S3C2410_UFCON, cfg->ufcon | S3C2410_UFCON_RESETBOTH);  //S3C2410_UFCON:FIFO控制寄存器
wr_regl(port, S3C2410_UFCON, cfg->ufcon);

return 0;
}

static struct s3c24xx_uart_info s3c2440_uart_inf = { //针对S3C2440 UART的信息
.name = "Samsung S3C2440 UART",
.type = PORT_S3C2440,
.fifosize = 64,
.rx_fifomask = S3C2440_UFSTAT_RXMASK,
.rx_fifoshift = S3C2440_UFSTAT_RXSHIFT,
.rx_fifofull = S3C2440_UFSTAT_RXFULL,
.tx_fifofull = S3C2440_UFSTAT_TXFULL,
.tx_fifomask = S3C2440_UFSTAT_TXMASK,
.tx_fifoshift = S3C2440_UFSTAT_TXSHIFT,
.get_clksrc = s3c2440_serial_getsource,
.set_clksrc = s3c2440_serial_setsource,
.reset_port = s3c2440_serial_resetport,
};

/* device management */

static int s3c2440_serial_probe(struct platform_device *dev)//平台设备的探测函数
{
dbg("s3c2440_serial_probe: dev=%p\n", dev);
return s3c24xx_serial_probe(dev, &s3c2440_uart_inf); // 初始化端口并添加端口。
}

static struct platform_driver s3c2440_serial_driver = { //初始化平台设备结构体
.probe = s3c2440_serial_probe,
.remove = __devexit_p(s3c24xx_serial_remove),
.driver = {
.name = "s3c2440-uart",
.owner = THIS_MODULE,
},
};

s3c24xx_console_init(&s3c2440_serial_driver, &s3c2440_uart_inf); //宏定义, 调用samsung.c中的函数s3c24xx_serial_initconsole
static int __init s3c2440_serial_init(void)
{
return s3c24xx_serial_init(&s3c2440_serial_driver, &s3c2440_uart_inf);//调用平台设备的驱动注册函数platform_driver_register()
}

static void __exit s3c2440_serial_exit(void)
{
platform_driver_unregister(&s3c2440_serial_driver);
}

module_init(s3c2440_serial_init);
module_exit(s3c2440_serial_exit);

MODULE_DESCRIPTION("Samsung S3C2440,S3C2442 SoC Serial port driver");
MODULE_AUTHOR("Ben Dooks ");
MODULE_LICENSE("GPL v2");
MODULE_ALIAS("platform:s3c2440-uart");


samsung.c文件:
/* linux/drivers/serial/samsuing.c*/
#if defined(CONFIG_SERIAL_SAMSUNG_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include

#include

#include
#include

#include

#include "samsung.h"

/* UART name and device definitions */

#define S3C24XX_SERIAL_NAME "ttySAC"
#define S3C24XX_SERIAL_MAJOR 204
#define S3C24XX_SERIAL_MINOR 64

/* macros to change one thing to another */

#define tx_enabled(port) ((port)->unused[0])
#define rx_enabled(port) ((port)->unused[1])

/* flag to ignore all characters comming in */
#define RXSTAT_DUMMY_READ (0x10000000)    //接收数据状态寄存器

static inline struct s3c24xx_uart_port *to_ourport(struct uart_port *port)
{
return container_of(port, struct s3c24xx_uart_port, port); //根据port获取结构体本身的指针
}

/* translate a port to the device name */

static inline const char *s3c24xx_serial_portname(struct uart_port *port)
{
return to_platform_device(port->dev)->name;       //to_platform_device(x) == container_of((x), struct platform_device, dev)
}//因此可以初始化platform_device的name

static int s3c24xx_serial_txempty_nofifo(struct uart_port *port)
{
return (rd_regl(port, S3C2410_UTRSTAT) & S3C2410_UTRSTAT_TXE);//rd_regl读S3C2410_UTRSTAT(发送接收状态寄存器)
} //检查发送缓冲区是否为空, 非FIFO模式

static void s3c24xx_serial_rx_enable(struct uart_port *port) //启动接收数据
{
unsigned long flags;
unsigned int ucon, ufcon;
int count = 10000;

spin_lock_irqsave(&port->lock, flags);

while (--count && !s3c24xx_serial_txempty_nofifo(port))
udelay(100);

ufcon = rd_regl(port, S3C2410_UFCON);
ufcon |= S3C2410_UFCON_RESETRX;
wr_regl(port, S3C2410_UFCON, ufcon);

ucon = rd_regl(port, S3C2410_UCON);
ucon |= S3C2410_UCON_RXIRQMODE; //设置接收数据中断
wr_regl(port, S3C2410_UCON, ucon);

rx_enabled(port) = 1;
spin_unlock_irqrestore(&port->lock, flags);
}

static void s3c24xx_serial_rx_disable(struct uart_port *port) //禁止接收数据
{
unsigned long flags;
unsigned int ucon;

spin_lock_irqsave(&port->lock, flags);

ucon = rd_regl(port, S3C2410_UCON);
ucon &= ~S3C2410_UCON_RXIRQMODE;
wr_regl(port, S3C2410_UCON, ucon);

rx_enabled(port) = 0;
spin_unlock_irqrestore(&port->lock, flags);
}

static void s3c24xx_serial_stop_tx(struct uart_port *port) //停止发送数据
{
struct s3c24xx_uart_port *ourport = to_ourport(port);

if (tx_enabled(port)) {
disable_irq_nosync(ourport->tx_irq);   //  disable_irq_nosync   禁止中断立即返回 的。这样,使用后者将会更快,但是可能会让你的驱动程序处于竞态下。
                                                                     //   disable_irq                 禁止中断,而且等待当前正在执行的中断处理程序完成.
tx_enabled(port) = 0;
if (port->flags & UPF_CONS_FLOW) // 判断 端口是否已 enabling flow control
s3c24xx_serial_rx_enable(port);
}
}

static void s3c24xx_serial_start_tx(struct uart_port *port) //启动发送数据
{
struct s3c24xx_uart_port *ourport = to_ourport(port);

if (!tx_enabled(port)) {
if (port->flags & UPF_CONS_FLOW)
s3c24xx_serial_rx_disable(port);               // 启动发送数据中断,所以要禁止接收中断。

enable_irq(ourport->tx_irq);
tx_enabled(port) = 1;
}
}


static void s3c24xx_serial_stop_rx(struct uart_port *port) // 停止接收数据
{
struct s3c24xx_uart_port *ourport = to_ourport(port);

if (rx_enabled(port)) {
dbg("s3c24xx_serial_stop_rx: port=%p\n", port);
disable_irq_nosync(ourport->rx_irq);
rx_enabled(port) = 0;
}
}

static void s3c24xx_serial_enable_ms(struct uart_port *port)
{
}

static inline struct s3c24xx_uart_info *s3c24xx_port_to_info(struct uart_port *port)
{
return to_ourport(port)->info;//调用container_of, 获取s3c24xx_uart_info信息
}

static inline struct s3c2410_uartcfg *s3c24xx_port_to_cfg(struct uart_port *port)
{
if (port->dev == NULL)
return NULL;

return (struct s3c2410_uartcfg *)port->dev->platform_data;  // platform_data的获取在。。。。
}

static int s3c24xx_serial_rx_fifocnt(struct s3c24xx_uart_port *ourport,
    unsigned long ufstat)//获取fifo中已有的数据大小
{
struct s3c24xx_uart_info *info = ourport->info;

if (ufstat & info->rx_fifofull)
return info->fifosize;

return (ufstat & info->rx_fifomask) >> info->rx_fifoshift;
}


/* ? - where has parity gone?? */
#define S3C2410_UERSTAT_PARITY (0x1000)    // 奇偶校验错误

static irqreturn_t
s3c24xx_serial_rx_chars(int irq, void *dev_id) //接收中断处理函数
{
struct s3c24xx_uart_port *ourport = dev_id;
struct uart_port *port = &ourport->port; //获得uart_port
struct tty_struct *tty = port->state->port.tty; //获得tty_struct
unsigned int ufcon, ch, flag, ufstat, uerstat;
int max_count = 64;

while (max_count-- > 0) {
ufcon = rd_regl(port, S3C2410_UFCON);
ufstat = rd_regl(port, S3C2410_UFSTAT);

if (s3c24xx_serial_rx_fifocnt(ourport, ufstat) == 0)
break;

uerstat = rd_regl(port, S3C2410_UERSTAT);
ch = rd_regb(port, S3C2410_URXH); //从寄存器读出数据

if (port->flags & UPF_CONS_FLOW) {
int txe = s3c24xx_serial_txempty_nofifo(port);

if (rx_enabled(port)) { //端口为使能接收状态
if (!txe) { //发送缓冲区为空
rx_enabled(port) = 0;
continue;
}
} else { //端口为禁止接收状态
if (txe) { //发送缓冲区非空
ufcon |= S3C2410_UFCON_RESETRX;
wr_regl(port, S3C2410_UFCON, ufcon);
rx_enabled(port) = 1;
goto out;
}
continue;
}
}

/* insert the character into the buffer */

flag = TTY_NORMAL;
port->icount.rx++;

if (unlikely(uerstat & S3C2410_UERSTAT_ANY)) {
dbg("rxerr: port ch=0x%02x, rxs=0x%08x\n",
   ch, uerstat);

/* check for break */
if (uerstat & S3C2410_UERSTAT_BREAK) {
dbg("break!\n");
port->icount.brk++;
if (uart_handle_break(port))
   goto ignore_char;
}

if (uerstat & S3C2410_UERSTAT_FRAME)
port->icount.frame++;
if (uerstat & S3C2410_UERSTAT_OVERRUN)
port->icount.overrun++;

uerstat &= port->read_status_mask;

if (uerstat & S3C2410_UERSTAT_BREAK)
flag = TTY_BREAK;
else if (uerstat & S3C2410_UERSTAT_PARITY)
flag = TTY_PARITY;
else if (uerstat & (S3C2410_UERSTAT_FRAME |
   S3C2410_UERSTAT_OVERRUN))
flag = TTY_FRAME;
}

if (uart_handle_sysrq_char(port, ch))
goto ignore_char;

uart_insert_char(port, uerstat, S3C2410_UERSTAT_OVERRUN, ch, flag);           //插入字符到tty设备的flip缓冲

 ignore_char:
continue;
}
tty_flip_buffer_push(tty); //刷新tty设备的flip缓冲

 out:
return IRQ_HANDLED;
}

static irqreturn_t s3c24xx_serial_tx_chars(int irq, void *id) //发送中断处理函数
{
struct s3c24xx_uart_port *ourport = id;
struct uart_port *port = &ourport->port;
struct circ_buf *xmit = &port->state->xmit;   //得到环形缓冲区
int count = 256;                                                 //一次最多发送的字符数

if (port->x_char) { //如果定义了xchar, 发送
wr_regb(port, S3C2410_UTXH, port->x_char);
port->icount.tx++;
port->x_char = 0;
goto out;
}

/* if there isnt anything more to transmit, or the uart is now
* stopped, disable the uart and exit
*/

if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
s3c24xx_serial_stop_tx(port);
goto out;
}

/* try and drain the buffer... */

while (!uart_circ_empty(xmit) && count-- > 0) {
if (rd_regl(port, S3C2410_UFSTAT) & ourport->info->tx_fifofull)
break;

wr_regb(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
port->icount.tx++;
}

if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)//如果环形缓冲区中剩余的字符少于WAKEUP_CHARS, 唤醒上层
uart_write_wakeup(port);

if (uart_circ_empty(xmit)) //如果发送环形buffer为空
s3c24xx_serial_stop_tx(port); //停止发送

 out:
return IRQ_HANDLED;
}

static unsigned int s3c24xx_serial_tx_empty(struct uart_port *port)//判断发送缓冲区/FIFO是否为空
{
struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);//FIFO模式,检查UFSTATn寄存器
unsigned long ufstat = rd_regl(port, S3C2410_UFSTAT);
unsigned long ufcon = rd_regl(port, S3C2410_UFCON);

if (ufcon & S3C2410_UFCON_FIFOMODE) {
if ((ufstat & info->tx_fifomask) != 0 || //tx fifo数据非0
   (ufstat & info->tx_fifofull)) //tx fifo满
return 0; //非空返回0

return 1; //空
}

return s3c24xx_serial_txempty_nofifo(port);
}

/* no modem control lines */
static unsigned int s3c24xx_serial_get_mctrl(struct uart_port *port)
{
unsigned int umstat = rd_regb(port, S3C2410_UMSTAT);

if (umstat & S3C2410_UMSTAT_CTS)
return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
else
return TIOCM_CAR | TIOCM_DSR;
}

static void s3c24xx_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
/* todo - possibly remove AFC and do manual CTS */
}

static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state)
{
unsigned long flags;
unsigned int ucon;

spin_lock_irqsave(&port->lock, flags);

ucon = rd_regl(port, S3C2410_UCON);

if (break_state)
ucon |= S3C2410_UCON_SBREAK;
else
ucon &= ~S3C2410_UCON_SBREAK;

wr_regl(port, S3C2410_UCON, ucon);

spin_unlock_irqrestore(&port->lock, flags);
}

static void s3c24xx_serial_shutdown(struct uart_port *port)//释放中断,禁止发送和接收
{
struct s3c24xx_uart_port *ourport = to_ourport(port);

if (ourport->tx_claimed) {
free_irq(ourport->tx_irq, ourport);
tx_enabled(port) = 0; //设置发送使能状态为0
ourport->tx_claimed = 0;
}

if (ourport->rx_claimed) {
free_irq(ourport->rx_irq, ourport);
ourport->rx_claimed = 0;
rx_enabled(port) = 0; //设置接收使能状态为0
}
}


static int s3c24xx_serial_startup(struct uart_port *port)     //启动端口,申请端口的发送,接收中断,使能端口的发送和接收
{
struct s3c24xx_uart_port *ourport = to_ourport(port);
int ret;

dbg("s3c24xx_serial_startup: port=%p (%08lx,%p)\n",
   port->mapbase, port->membase);

rx_enabled(port) = 1; //设置接收使能状态为1

ret = request_irq(ourport->rx_irq, s3c24xx_serial_rx_chars, 0, //申请接收中断
 s3c24xx_serial_portname(port), ourport);

if (ret != 0) {
printk(KERN_ERR "cannot get irq %d\n", ourport->rx_irq);
return ret;
}

ourport->rx_claimed = 1;

dbg("requesting tx irq...\n");

tx_enabled(port) = 1; //设置发送使能状态为1

ret = request_irq(ourport->tx_irq, s3c24xx_serial_tx_chars, 0,//申请发送中断
 s3c24xx_serial_portname(port), ourport);

if (ret) {
printk(KERN_ERR "cannot get irq %d\n", ourport->tx_irq);
goto err;
}

ourport->tx_claimed = 1;

dbg("s3c24xx_serial_startup ok\n");

/* the port reset code should have done the correct
* register setup for the port controls */
 if (port->line == 2) {
  s3c2410_gpio_cfgpin(S3C2410_GPH(6), S3C2410_GPH6_TXD2);
  s3c2410_gpio_pullup(S3C2410_GPH(6), 1);
  s3c2410_gpio_cfgpin(S3C2410_GPH(7), S3C2410_GPH7_RXD2);
  s3c2410_gpio_pullup(S3C2410_GPH(7), 1);
 }
 
return ret;

 err:
s3c24xx_serial_shutdown(port);
return ret;
}

/* power power management control */

static void s3c24xx_serial_pm(struct uart_port *port, unsigned int level,
     unsigned int old)
{
struct s3c24xx_uart_port *ourport = to_ourport(port);

ourport->pm_level = level;

switch (level) {
case 3:
if (!IS_ERR(ourport->baudclk) && ourport->baudclk != NULL)
clk_disable(ourport->baudclk);

clk_disable(ourport->clk);
break;

case 0:
clk_enable(ourport->clk);

if (!IS_ERR(ourport->baudclk) && ourport->baudclk != NULL)
clk_enable(ourport->baudclk);

break;
default:
printk(KERN_ERR "s3c24xx_serial: unknown pm %d\n", level);
}
}

/* baud rate calculation
 *
 * The UARTs on the S3C2410/S3C2440 can take their clocks from a number
 * of different sources, including the peripheral clock ("pclk") and an
 * external clock ("uclk"). The S3C2440 also adds the core clock ("fclk")
 * with a programmable extra divisor.
 *
 * The following code goes through the clock sources, and calculates the
 * baud clocks (and the resultant actual baud rates) and then tries to
 * pick the closest one and select that.
 *
*/


#define MAX_CLKS (8)

static struct s3c24xx_uart_clksrc tmp_clksrc = {
.name = "pclk",
.min_baud = 0,
.max_baud = 0,
.divisor = 1,
};

static inline int
s3c24xx_serial_getsource(struct uart_port *port, struct s3c24xx_uart_clksrc *c)
{
struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);

return (info->get_clksrc)(port, c);
}

static inline int
s3c24xx_serial_setsource(struct uart_port *port, struct s3c24xx_uart_clksrc *c)
{
struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);

return (info->set_clksrc)(port, c);
}

struct baud_calc {
struct s3c24xx_uart_clksrc *clksrc;
unsigned int calc;
unsigned int divslot;
unsigned int quot;
struct clk *src;
};

static int s3c24xx_serial_calcbaud(struct baud_calc *calc,
  struct uart_port *port,
  struct s3c24xx_uart_clksrc *clksrc,
  unsigned int baud)
{
struct s3c24xx_uart_port *ourport = to_ourport(port);
unsigned long rate;

calc->src = clk_get(port->dev, clksrc->name);
if (calc->src == NULL || IS_ERR(calc->src))
return 0;

rate = clk_get_rate(calc->src);
rate /= clksrc->divisor;

calc->clksrc = clksrc;

if (ourport->info->has_divslot) {
unsigned long div = rate / baud;

/* The UDIVSLOT register on the newer UARTs allows us to
* get a divisor adjustment of 1/16th on the baud clock.
*
* We don't keep the UDIVSLOT value (the 16ths we calculated
* by not multiplying the baud by 16) as it is easy enough
* to recalculate.
*/

calc->quot = div / 16;
calc->calc = rate / div;
} else {
calc->quot = (rate + (8 * baud)) / (16 * baud);
calc->calc = (rate / (calc->quot * 16));
}

calc->quot--;
return 1;
}

static unsigned int s3c24xx_serial_getclk(struct uart_port *port,
 struct s3c24xx_uart_clksrc **clksrc,
 struct clk **clk,
 unsigned int baud)
{
struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
struct s3c24xx_uart_clksrc *clkp;
struct baud_calc res[MAX_CLKS];
struct baud_calc *resptr, *best, *sptr;
int i;

clkp = cfg->clocks;
best = NULL;

if (cfg->clocks_size < 2) {
if (cfg->clocks_size == 0)
clkp = &tmp_clksrc;

/* check to see if we're sourcing fclk, and if so we're
* going to have to update the clock source
*/

if (strcmp(clkp->name, "fclk") == 0) {
struct s3c24xx_uart_clksrc src;

s3c24xx_serial_getsource(port, &src);

/* check that the port already using fclk, and if
* not, then re-select fclk
*/

if (strcmp(src.name, clkp->name) == 0) {
s3c24xx_serial_setsource(port, clkp);
s3c24xx_serial_getsource(port, &src);
}

clkp->divisor = src.divisor;
}

s3c24xx_serial_calcbaud(res, port, clkp, baud);
best = res;
resptr = best + 1;
} else {
resptr = res;

for (i = 0; i < cfg->clocks_size; i++, clkp++) {
if (s3c24xx_serial_calcbaud(resptr, port, clkp, baud))
resptr++;
}
}

/* ok, we now need to select the best clock we found */

if (!best) {
unsigned int deviation = (1<<30)|((1<<30)-1);
int calc_deviation;

for (sptr = res; sptr < resptr; sptr++) {
calc_deviation = baud - sptr->calc;
if (calc_deviation < 0)
calc_deviation = -calc_deviation;

if (calc_deviation < deviation) {
best = sptr;
deviation = calc_deviation;
}
}
}

/* store results to pass back */

*clksrc = best->clksrc;
*clk    = best->src;

return best->quot;
}

/* udivslot_table[]
 *
 * This table takes the fractional value of the baud divisor and gives
 * the recommended setting for the UDIVSLOT register.
 */
static u16 udivslot_table[16] = {
[0] = 0x0000,
[1] = 0x0080,
[2] = 0x0808,
[3] = 0x0888,
[4] = 0x2222,
[5] = 0x4924,
[6] = 0x4A52,
[7] = 0x54AA,
[8] = 0x5555,
[9] = 0xD555,
[10] = 0xD5D5,
[11] = 0xDDD5,
[12] = 0xDDDD,
[13] = 0xDFDD,
[14] = 0xDFDF,
[15] = 0xFFDF,
};

static void s3c24xx_serial_set_termios(struct uart_port *port, //端口参数设置
      struct ktermios *termios,
      struct ktermios *old)
{
struct s3c2410_uartcfg *cfg = s3c24xx_port_to_cfg(port);
struct s3c24xx_uart_port *ourport = to_ourport(port);
struct s3c24xx_uart_clksrc *clksrc = NULL;
struct clk *clk = NULL;
unsigned long flags;
unsigned int baud, quot;
unsigned int ulcon;
unsigned int umcon;
unsigned int udivslot = 0;

/*
* We don't support modem control lines.
*/
termios->c_cflag &= ~(HUPCL | CMSPAR);
termios->c_cflag |= CLOCAL;

/*
* Ask the core to calculate the divisor for us.
*/

baud = uart_get_baud_rate(port, termios, old, 0, 115200*8);//请求计算分频,以便产生正确的波特率

if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
quot = port->custom_divisor;
else
quot = s3c24xx_serial_getclk(port, &clksrc, &clk, baud);

/* check to see if we need  to change clock source */

if (ourport->clksrc != clksrc || ourport->baudclk != clk) {
dbg("selecting clock %p\n", clk);
s3c24xx_serial_setsource(port, clksrc);

if (ourport->baudclk != NULL && !IS_ERR(ourport->baudclk)) {
clk_disable(ourport->baudclk);
ourport->baudclk  = NULL;
}

clk_enable(clk);

ourport->clksrc = clksrc;
ourport->baudclk = clk;
ourport->baudclk_rate = clk ? clk_get_rate(clk) : 0;
}

if (ourport->info->has_divslot) {
unsigned int div = ourport->baudclk_rate / baud;

udivslot = udivslot_table[div & 15];
dbg("udivslot = %04x (div %d)\n", udivslot, div & 15);
}

switch (termios->c_cflag & CSIZE) { //设置数据字长
case CS5:
dbg("config: 5bits/char\n");
ulcon = S3C2410_LCON_CS5;
break;
case CS6:
dbg("config: 6bits/char\n");
ulcon = S3C2410_LCON_CS6;
break;
case CS7:
dbg("config: 7bits/char\n");
ulcon = S3C2410_LCON_CS7;
break;
case CS8:
default:
dbg("config: 8bits/char\n");
ulcon = S3C2410_LCON_CS8;
break;
}

/* preserve original lcon IR settings */
ulcon |= (cfg->ulcon & S3C2410_LCON_IRM);

if (termios->c_cflag & CSTOPB)
ulcon |= S3C2410_LCON_STOPB;  // 是否要求设置两个停止位(CSTOPB)

umcon = (termios->c_cflag & CRTSCTS) ? S3C2410_UMCOM_AFC : 0;

if (termios->c_cflag & PARENB) {
if (termios->c_cflag & PARODD)
ulcon |= S3C2410_LCON_PODD; //奇校验
else
ulcon |= S3C2410_LCON_PEVEN; //偶校验
} else {
ulcon |= S3C2410_LCON_PNONE; //无校验
}

spin_lock_irqsave(&port->lock, flags);

dbg("setting ulcon to %08x, brddiv to %d, udivslot %08x\n",
   ulcon, quot, udivslot);

wr_regl(port, S3C2410_ULCON, ulcon);
wr_regl(port, S3C2410_UBRDIV, quot);
wr_regl(port, S3C2410_UMCON, umcon);

if (ourport->info->has_divslot)
wr_regl(port, S3C2443_DIVSLOT, udivslot);

dbg("uart: ulcon = 0x%08x, ucon = 0x%08x, ufcon = 0x%08x\n",
   rd_regl(port, S3C2410_ULCON),
   rd_regl(port, S3C2410_UCON),
   rd_regl(port, S3C2410_UFCON));

/*
* Update the per-port timeout.
*/
uart_update_timeout(port, termios->c_cflag, baud); //更新端口的超时

/*
* Which character status flags are we interested in?
*/
port->read_status_mask = S3C2410_UERSTAT_OVERRUN;
if (termios->c_iflag & INPCK)
port->read_status_mask |= S3C2410_UERSTAT_FRAME | S3C2410_UERSTAT_PARITY;

/*
* Which character status flags should we ignore?
*/
port->ignore_status_mask = 0;
if (termios->c_iflag & IGNPAR)
port->ignore_status_mask |= S3C2410_UERSTAT_OVERRUN;
if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
port->ignore_status_mask |= S3C2410_UERSTAT_FRAME;

/*
* Ignore all characters if CREAD is not set.
*/
if ((termios->c_cflag & CREAD) == 0)
port->ignore_status_mask |= RXSTAT_DUMMY_READ;

spin_unlock_irqrestore(&port->lock, flags);
}

static const char *s3c24xx_serial_type(struct uart_port *port)
{
switch (port->type) {
case PORT_S3C2410:
return "S3C2410";
case PORT_S3C2440:
return "S3C2440";
case PORT_S3C2412:
return "S3C2412";
case PORT_S3C6400:
return "S3C6400/10";
default:
return NULL;
}
}

#define MAP_SIZE (0x100)

static void s3c24xx_serial_release_port(struct uart_port *port)
{
release_mem_region(port->mapbase, MAP_SIZE);
}

static int s3c24xx_serial_request_port(struct uart_port *port)
{
const char *name = s3c24xx_serial_portname(port);
return request_mem_region(port->mapbase, MAP_SIZE, name) ? 0 : -EBUSY;
}

static void s3c24xx_serial_config_port(struct uart_port *port, int flags)
{
struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);

if (flags & UART_CONFIG_TYPE &&
   s3c24xx_serial_request_port(port) == 0)
port->type = info->type;
}

/*
 * verify the new serial_struct (for TIOCSSERIAL).
 */
static int
s3c24xx_serial_verify_port(struct uart_port *port, struct serial_struct *ser)
{
struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);

if (ser->type != PORT_UNKNOWN && ser->type != info->type)
return -EINVAL;

return 0;
}


#ifdef CONFIG_SERIAL_SAMSUNG_CONSOLE

static struct console s3c24xx_serial_console;

#define S3C24XX_SERIAL_CONSOLE &s3c24xx_serial_console
#else
#define S3C24XX_SERIAL_CONSOLE NULL
#endif

static struct uart_ops s3c24xx_serial_ops = {
.pm = s3c24xx_serial_pm,
.tx_empty = s3c24xx_serial_tx_empty, //发送缓冲区空
.get_mctrl = s3c24xx_serial_get_mctrl, //获取modem控制设置
.set_mctrl = s3c24xx_serial_set_mctrl, //设置modem控制
.stop_tx = s3c24xx_serial_stop_tx, //停止传输字符
.start_tx = s3c24xx_serial_start_tx, //开始传输字符
.stop_rx = s3c24xx_serial_stop_rx, //停止接收字符
.enable_ms = s3c24xx_serial_enable_ms, //modem状态中断时能
.break_ctl = s3c24xx_serial_break_ctl, //控制break信号的传输
.startup = s3c24xx_serial_startup, //启动端口
.shutdown = s3c24xx_serial_shutdown, //关闭端口
.set_termios = s3c24xx_serial_set_termios, //改变端口参数
.type = s3c24xx_serial_type, //返回描述特定端口的常量字符串指针
.release_port = s3c24xx_serial_release_port, //释放端口所占的内存和IO资源
.request_port = s3c24xx_serial_request_port, //申请端口所需的内存和IO资源
.config_port = s3c24xx_serial_config_port, //执行端口所需的自动配置步骤
.verify_port = s3c24xx_serial_verify_port, //验证新的串行端口信息
};


static struct uart_driver s3c24xx_uart_drv = {
.owner = THIS_MODULE,
.dev_name = "s3c2410_serial",
.nr = CONFIG_SERIAL_SAMSUNG_UARTS,
.cons = S3C24XX_SERIAL_CONSOLE,
.driver_name = S3C24XX_SERIAL_NAME,
.major = S3C24XX_SERIAL_MAJOR,
.minor = S3C24XX_SERIAL_MINOR,
};

static struct s3c24xx_uart_port s3c24xx_serial_ports[CONFIG_SERIAL_SAMSUNG_UARTS] = {
[0] = {
.port = {
.lock = __SPIN_LOCK_UNLOCKED(s3c24xx_serial_ports[0].port.lock),
.iotype = UPIO_MEM,
.irq = IRQ_S3CUART_RX0,  
 
//   #define IRQ_S3CUART_RX0                      S3C2410_IRQSUB(0) /* 70 */
//   #define S3C2410_IRQSUB(x)                    S3C2410_IRQ((x)+54)
//  #define S3C2410_IRQ(x)                             ((x) + S3C2410_CPUIRQ_OFFSET)
//  #define S3C2410_CPUIRQ_OFFSET       (16)
 
.uartclk = 0,
.fifosize = 16,
.ops = &s3c24xx_serial_ops,
.flags = UPF_BOOT_AUTOCONF,
.line = 0, // /* UART port number */ 端口索引
}
},
[1] = {
.port = {
.lock = __SPIN_LOCK_UNLOCKED(s3c24xx_serial_ports[1].port.lock),
.iotype = UPIO_MEM,
.irq = IRQ_S3CUART_RX1,    //#define IRQ_S3CUART_RX1       S3C2410_IRQSUB(3) /* 73 */
.uartclk = 0,
.fifosize = 16,
.ops = &s3c24xx_serial_ops,
.flags = UPF_BOOT_AUTOCONF,
.line = 1,
}
},
#if CONFIG_SERIAL_SAMSUNG_UARTS > 2

[2] = {
.port = {
.lock = __SPIN_LOCK_UNLOCKED(s3c24xx_serial_ports[2].port.lock),
.iotype = UPIO_MEM,
.irq = IRQ_S3CUART_RX2,
.uartclk = 0,
.fifosize = 16,
.ops = &s3c24xx_serial_ops,
.flags = UPF_BOOT_AUTOCONF,
.line = 2,
}
},
#endif
#if CONFIG_SERIAL_SAMSUNG_UARTS > 3
[3] = {
.port = {
.lock = __SPIN_LOCK_UNLOCKED(s3c24xx_serial_ports[3].port.lock),
.iotype = UPIO_MEM,
.irq = IRQ_S3CUART_RX3,
.uartclk = 0,
.fifosize = 16,
.ops = &s3c24xx_serial_ops,
.flags = UPF_BOOT_AUTOCONF,
.line = 3,
}
}
#endif
};

/* s3c24xx_serial_resetport
 *
 * wrapper to call the specific reset for this port (reset the fifos
 * and the settings)
*/

static inline int s3c24xx_serial_resetport(struct uart_port *port,
  struct s3c2410_uartcfg *cfg)
{
struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);

return (info->reset_port)(port, cfg);
}


#ifdef CONFIG_CPU_FREQ

static int s3c24xx_serial_cpufreq_transition(struct notifier_block *nb,
    unsigned long val, void *data) 
{
struct s3c24xx_uart_port *port;
struct uart_port *uport;

port = container_of(nb, struct s3c24xx_uart_port, freq_transition);
uport = &port->port;

/* check to see if port is enabled */

if (port->pm_level != 0)
return 0;

/* try and work out if the baudrate is changing, we can detect
* a change in rate, but we do not have support for detecting
* a disturbance in the clock-rate over the change.
*/

if (IS_ERR(port->clk))
goto exit;

if (port->baudclk_rate == clk_get_rate(port->clk))
goto exit;

if (val == CPUFREQ_PRECHANGE) {
/* we should really shut the port down whilst the
* frequency change is in progress. */

} else if (val == CPUFREQ_POSTCHANGE) {
struct ktermios *termios;
struct tty_struct *tty;

if (uport->state == NULL)
goto exit;

tty = uport->state->port.tty;

if (tty == NULL)
goto exit;

termios = tty->termios;

if (termios == NULL) {
printk(KERN_WARNING "%s: no termios?\n", __func__);
goto exit;
}

s3c24xx_serial_set_termios(uport, termios, NULL);
}

 exit:
return 0;
}

static inline int s3c24xx_serial_cpufreq_register(struct s3c24xx_uart_port *port)
{
port->freq_transition.notifier_call = s3c24xx_serial_cpufreq_transition;

return cpufreq_register_notifier(&port->freq_transition,
CPUFREQ_TRANSITION_NOTIFIER);
}

static inline void s3c24xx_serial_cpufreq_deregister(struct s3c24xx_uart_port *port)
{
cpufreq_unregister_notifier(&port->freq_transition,
   CPUFREQ_TRANSITION_NOTIFIER);
}

#else
static inline int s3c24xx_serial_cpufreq_register(struct s3c24xx_uart_port *port)
{
return 0;
}

static inline void s3c24xx_serial_cpufreq_deregister(struct s3c24xx_uart_port *port)
{
}
#endif

/* s3c24xx_serial_init_port
 *
 * initialise a single serial port from the platform device given
 */

static int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport,
   struct s3c24xx_uart_info *info,
   struct platform_device *platdev)
{
struct uart_port *port = &ourport->port;
struct s3c2410_uartcfg *cfg;
struct resource *res;
int ret;

dbg("s3c24xx_serial_init_port: port=%p, platdev=%p\n", port, platdev);

if (platdev == NULL)
return -ENODEV;

cfg = s3c24xx_dev_to_cfg(&platdev->dev);

if (port->mapbase != 0)
return 0;

if (cfg->hwport > CONFIG_SERIAL_SAMSUNG_UARTS) {
printk(KERN_ERR "%s: port %d bigger than %d\n", __func__,
      cfg->hwport, CONFIG_SERIAL_SAMSUNG_UARTS);
return -ERANGE;
}

/* setup info for port */
port->dev = &platdev->dev;
ourport->info = info;

/* copy the info in from provided structure */
ourport->port.fifosize = info->fifosize;

dbg("s3c24xx_serial_init_port: %p (hw %d)...\n", port, cfg->hwport);

port->uartclk = 1;

if (cfg->uart_flags & UPF_CONS_FLOW) {
dbg("s3c24xx_serial_init_port: enabling flow control\n");
port->flags |= UPF_CONS_FLOW;
}

/* sort our the physical and virtual addresses for each UART */

res = platform_get_resource(platdev, IORESOURCE_MEM, 0);    //遍历resource资源列表,返回类型一致的资源。
if (res == NULL) {
printk(KERN_ERR "failed to find memory resource for uart\n");
return -EINVAL;
}

dbg("resource %p (%lx..%lx)\n", res, res->start, res->end);
 
port->mapbase = res->start;        /* 设置串口的寄存器基地址(物理)*/
port->membase = S3C_VA_UART + res->start - (S3C_PA_UART & 0xfff00000);
ret = platform_get_irq(platdev, 0); // 调用platform_get_resource(platdev, IORESOURCE_IRQ, 0);返回第一次遇到的IORESOURCE_IRQ类型的resource的起始地址start。
if (ret < 0)
port->irq = 0;
else {
port->irq = ret;
ourport->rx_irq = ret;
ourport->tx_irq = ret + 1;
}
ret = platform_get_irq(platdev, 1);// 调用platform_get_resource(platdev, IORESOURCE_IRQ, 1);返回第一次遇到的IORESOURCE_IRQ类型的resource的起始地址start。
if (ret > 0)
ourport->tx_irq = ret;

ourport->clk = clk_get(&platdev->dev, "uart");

dbg("port: map=%08x, mem=%08x, irq=%d (%d,%d), clock=%ld\n",
   port->mapbase, port->membase, port->irq,
   ourport->rx_irq, ourport->tx_irq, port->uartclk);

/* reset the fifos (and setup the uart) */
s3c24xx_serial_resetport(port, cfg);
return 0;
}

static ssize_t s3c24xx_serial_show_clksrc(struct device *dev,
 struct device_attribute *attr,
 char *buf)
{
struct uart_port *port = s3c24xx_dev_to_port(dev);
struct s3c24xx_uart_port *ourport = to_ourport(port);

return snprintf(buf, PAGE_SIZE, "* %s\n", ourport->clksrc->name);
}

static DEVICE_ATTR(clock_source, S_IRUGO, s3c24xx_serial_show_clksrc, NULL); //声明 dev_attr_clock_source属性,在s3c24xx_serial_probe中建立该属性文件。

/* Device driver serial port probe */

static int probe_index; //静态变量,端口探测索引。

int s3c24xx_serial_probe(struct platform_device *dev,
struct s3c24xx_uart_info *info)
{
struct s3c24xx_uart_port *ourport;
int ret;

dbg("s3c24xx_serial_probe(%p, %p) %d\n", dev, info, probe_index);

ourport = &s3c24xx_serial_ports[probe_index]; //s3c24xx_serial_ports为前面声明的s3c24xx_uart_port端口。
probe_index++;

dbg("%s: initialising port %p...\n", __func__, ourport);

ret = s3c24xx_serial_init_port(ourport, info, dev);
if (ret < 0)
goto probe_err;

dbg("%s: adding port\n", __func__);
uart_add_one_port(&s3c24xx_uart_drv, &ourport->port);
platform_set_drvdata(dev, &ourport->port);

ret = device_create_file(&dev->dev, & dev_attr_clock_source);
if (ret < 0)
printk(KERN_ERR "%s: failed to add clksrc attr.\n", __func__);

ret = s3c24xx_serial_cpufreq_register(ourport);
if (ret < 0)
dev_err(&dev->dev, "failed to add cpufreq notifier\n");

return 0;

 probe_err:
return ret;
}

EXPORT_SYMBOL_GPL(s3c24xx_serial_probe);

int __devexit s3c24xx_serial_remove(struct platform_device *dev)
{
struct uart_port *port = s3c24xx_dev_to_port(&dev->dev);

if (port) {
s3c24xx_serial_cpufreq_deregister(to_ourport(port));
device_remove_file(&dev->dev, &dev_attr_clock_source);
uart_remove_one_port(&s3c24xx_uart_drv, port);
}

return 0;
}

EXPORT_SYMBOL_GPL(s3c24xx_serial_remove);

/* UART power management code */

#ifdef CONFIG_PM

static int s3c24xx_serial_suspend(struct platform_device *dev, pm_message_t state)
{
struct uart_port *port = s3c24xx_dev_to_port(&dev->dev);

if (port)
uart_suspend_port(&s3c24xx_uart_drv, port);

return 0;
}

static int s3c24xx_serial_resume(struct platform_device *dev)
{
struct uart_port *port = s3c24xx_dev_to_port(&dev->dev);
struct s3c24xx_uart_port *ourport = to_ourport(port);

if (port) {
clk_enable(ourport->clk);
s3c24xx_serial_resetport(port, s3c24xx_port_to_cfg(port));
clk_disable(ourport->clk);

uart_resume_port(&s3c24xx_uart_drv, port);
}

return 0;
}
#endif

int s3c24xx_serial_init(struct platform_driver *drv,
struct s3c24xx_uart_info *info)                                       //在serial/s3c2410.c中被调用。
{
dbg("s3c24xx_serial_init(%p,%p)\n", drv, info);

#ifdef CONFIG_PM
drv->suspend = s3c24xx_serial_suspend;
drv->resume = s3c24xx_serial_resume;
#endif

return platform_driver_register(drv);
}

EXPORT_SYMBOL_GPL(s3c24xx_serial_init);

/* module initialisation code */

static int __init s3c24xx_serial_modinit(void)
{
int ret;

ret = uart_register_driver(&s3c24xx_uart_drv);
if (ret < 0) {
printk(KERN_ERR "failed to register UART driver\n");
return -1;
}

return 0;
}

static void __exit s3c24xx_serial_modexit(void)
{
uart_unregister_driver(&s3c24xx_uart_drv);
}

module_init(s3c24xx_serial_modinit);
module_exit(s3c24xx_serial_modexit);

/* Console code */

#ifdef CONFIG_SERIAL_SAMSUNG_CONSOLE

static struct uart_port *cons_uart;

static int
s3c24xx_serial_console_txrdy(struct uart_port *port, unsigned int ufcon) //发送数据就绪
{
struct s3c24xx_uart_info *info = s3c24xx_port_to_info(port);
unsigned long ufstat, utrstat;

if (ufcon & S3C2410_UFCON_FIFOMODE) {  // fifo模式
/* fifo mode - check amount of data in fifo registers... */

ufstat = rd_regl(port, S3C2410_UFSTAT);
return (ufstat & info->tx_fifofull) ? 0 : 1;
}

/* in non-fifo mode, we go and use the tx buffer empty */

utrstat = rd_regl(port, S3C2410_UTRSTAT);
return (utrstat & S3C2410_UTRSTAT_TXE) ? 1 : 0;
}

static void
s3c24xx_serial_console_putchar(struct uart_port *port, int ch) //写入字符
{
unsigned int ufcon = rd_regl(cons_uart, S3C2410_UFCON);
while (!s3c24xx_serial_console_txrdy(port, ufcon))
barrier();
wr_regb(cons_uart, S3C2410_UTXH, ch);
}

static void
s3c24xx_serial_console_write(struct console *co, const char *s,
    unsigned int count))   //写入count个字符;调用uart_console_write(struct uart_port *port, const char *s,   unsigned int count,   void (*putchar)(struct uart_port *, int))
{
uart_console_write(cons_uart, s, count, s3c24xx_serial_console_putchar);
}

static void __init
s3c24xx_serial_get_options(struct uart_port *port, int *baud,
  int *parity, int *bits) //获得端口的配置选项
{
struct s3c24xx_uart_clksrc clksrc;
struct clk *clk;
unsigned int ulcon;
unsigned int ucon;
unsigned int ubrdiv;
unsigned long rate;

ulcon  = rd_regl(port, S3C2410_ULCON);
ucon   = rd_regl(port, S3C2410_UCON);
ubrdiv = rd_regl(port, S3C2410_UBRDIV);

dbg("s3c24xx_serial_get_options: port=%p\n"
   "registers: ulcon=%08x, ucon=%08x, ubdriv=%08x\n",
   port, ulcon, ucon, ubrdiv);

if ((ucon & 0xf) != 0) {
/* consider the serial port configured if the tx/rx mode set */

switch (ulcon & S3C2410_LCON_CSMASK) { //获取数据字长,ulcon的低2位表示。
case S3C2410_LCON_CS5:  // 0x0
*bits = 5;
break;
case S3C2410_LCON_CS6: // 0x1
*bits = 6;
break;
case S3C2410_LCON_CS7 :// 0x 2
*bits = 7;
break;
default:
case S3C2410_LCON_CS8: // 0x3
*bits = 8;
break;
}

switch (ulcon & S3C2410_LCON_PMASK) {//使用奇偶校验掩码,获取奇偶校验方式。
case S3C2410_LCON_PEVEN:
*parity = 'e';
break;

case S3C2410_LCON_PODD:
*parity = 'o';
break;

case S3C2410_LCON_PNONE:
default:
*parity = 'n';
}

/* now calculate the baud rate */

s3c24xx_serial_getsource(port, &clksrc);

clk = clk_get(port->dev, clksrc.name);
if (!IS_ERR(clk) && clk != NULL)
rate = clk_get_rate(clk) / clksrc.divisor;
else
rate = 1;


*baud = rate / (16 * (ubrdiv + 1)); // 通过 ubrdiv = rd_regl(port, S3C2410_UBRDIV);
dbg("calculated baud %d\n", *baud);
}

}

/* s3c24xx_serial_init_ports
 *
 * initialise the serial ports from the machine provided initialisation
 * data.
*/

static int s3c24xx_serial_init_ports(struct s3c24xx_uart_info **info )   //初始化port
{
struct s3c24xx_uart_port *ptr = s3c24xx_serial_ports;
struct platform_device **platdev_ptr;
int i;

dbg("s3c24xx_serial_init_ports: initialising ports...\n");

platdev_ptr = s3c24xx_uart_devs;

for (i = 0; i < CONFIG_SERIAL_SAMSUNG_UARTS; i++, ptr++, platdev_ptr++) {
s3c24xx_serial_init_port(ptr, info[i], *platdev_ptr);
}

return 0;
}

static int __init
s3c24xx_serial_console_setup(struct console *co, char *options)
{
struct uart_port *port;
int baud = 9600;
int bits = 8;
int parity = 'n';
int flow = 'n';

dbg("s3c24xx_serial_console_setup: co=%p (%d), %s\n",
   co, co->index, options);

/* is this a valid port */

if (co->index == -1 || co->index >= CONFIG_SERIAL_SAMSUNG_UARTS)
co->index = 0;

port = &s3c24xx_serial_ports[co->index].port;

/* is the port configured? */

if (port->mapbase == 0x0) {
co->index = 0;
port = &s3c24xx_serial_ports[co->index].port;
}

cons_uart = port;

dbg("s3c24xx_serial_console_setup: port=%p (%d)\n", port, co->index);

/*
* Check whether an invalid uart number has been specified, and
* if so, search for the first available port that does have
* console support.
*/
if (options)
uart_parse_options(options, &baud, &parity, &bits, &flow);
else
s3c24xx_serial_get_options(port, &baud, &parity, &bits);

dbg("s3c24xx_serial_console_setup: baud %d\n", baud);

return uart_set_options(port, co, baud, parity, bits, flow);
}

/* s3c24xx_serial_initconsole
 *
 * initialise the console from one of the uart drivers
*/

static struct console s3c24xx_serial_console = {
.name = S3C24XX_SERIAL_NAME,
.device = uart_console_device,
.flags = CON_PRINTBUFFER,
.index = -1,
.write = s3c24xx_serial_console_write,
.setup = s3c24xx_serial_console_setup
};

int s3c24xx_serial_initconsole(struct platform_driver *drv,
      struct s3c24xx_uart_info **info)

{
struct platform_device *dev = s3c24xx_uart_devs[0];

dbg("s3c24xx_serial_initconsole\n");

/* select driver based on the cpu */

if (dev == NULL) {
printk(KERN_ERR "s3c24xx: no devices for console init\n");
return 0;
}

if (strcmp(dev->name, drv->driver.name) != 0)
return 0;

s3c24xx_serial_console.data = &s3c24xx_uart_drv;
s3c24xx_serial_init_ports(info);

register_console(&s3c24xx_serial_console);
return 0;
}

#endif /* CONFIG_SERIAL_SAMSUNG_CONSOLE */

MODULE_DESCRIPTION("Samsung SoC Serial port driver");
MODULE_AUTHOR("Ben Dooks ");
MODULE_LICENSE("GPL v2");

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