linux 串口驱动

一.核心数据结构

struct uart_driver {struct module *owner; /* 拥有该uart_driver的模块,一般为THIS_MODULE */const char *driver_name; /* 串口驱动名，串口设备文件名以驱动名为基础 */const char *dev_name; /* 串口设备名 */int major; /* 主设备号 */int minor; /* 次设备号 */int nr; /* 该uart_driver支持的串口个数(最大) */struct console *cons; /* 其对应的console.若该uart_driver支持serial console,否则为NULL *//** 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;}struct uart_port {spinlock_t lock; /* 串口端口锁 */unsigned int iobase; /* IO端口基地址 */unsigned char __iomem *membase; /* IO内存基地址,经映射(如ioremap)后的IO内存虚拟基地址 */unsigned int irq; /* 中断号 */unsigned int uartclk; /* 串口时钟 */unsigned int fifosize; /* 串口FIFO缓冲大小 */unsigned char x_char; /* xon/xoff字符 */unsigned char regshift; /* 寄存器位移 */unsigned char iotype; /* IO访问方式 */unsigned char unused1;#define UPIO_PORT (0) /* IO端口 */#define UPIO_HUB6 (1)#define UPIO_MEM (2) /* IO内存 */#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; /* 关心的Rx error status */unsigned int ignore_status_mask;/* 忽略的Rx error status */struct uart_info *info; /* pointer to parent info */struct uart_icount icount; /* 计数器 */struct console *cons; /* console结构体 */#ifdef CONFIG_SERIAL_CORE_CONSOLEunsigned long sysrq; /* sysrq timeout */#endifupf_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_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))#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; /* 当前的moden设置 */unsigned int timeout; /* character-based timeout */unsigned int type; /* 端口类型 */const struct uart_ops *ops; /* 串口端口操作函数集 */unsigned int custom_divisor;unsigned int line; /* 端口索引 */resource_size_t mapbase; /* IO内存物理基地址，可用于ioremap */struct device *dev; /* 父设备 */unsigned char hub6; /* this should be in the 8250 driver */unsigned char suspended;unsigned char unused[2];void *private_data; /* 端口私有数据,一般为platform数据指针 */};struct uart_icount {__u32 cts;__u32 dsr;__u32 rng;__u32 dcd;__u32 rx; /* 发送字符计数 */__u32 tx; /* 接受字符计数 */__u32 frame; /* 帧错误计数 */__u32 overrun; /* Rx FIFO溢出计数 */__u32 parity; /* 帧校验错误计数 */__u32 brk; /* break计数 */__u32 buf_overrun;};/* uart_info实例仅在串口端口打开时有效，它可能在串口关闭时被串口核心层释放。因此，在使用uart_port的uart_info成员时必须保证串口已打开。底层驱动和核心层驱动都可以修改uart_info实例。* This is the state information which is only valid when the port* is open; it may be freed by the core driver once the device has* been closed. Either the low level driver or the core can modify* stuff here.*/struct uart_info {struct tty_struct *tty;struct circ_buf xmit;uif_t flags;/** Definitions for info->flags. These are _private_ to serial_core, and* are specific to this structure. They may be queried by low level drivers.*/#define UIF_CHECK_CD ((__force uif_t) (1 << 25))#define UIF_CTS_FLOW ((__force uif_t) (1 << 26))#define UIF_NORMAL_ACTIVE ((__force uif_t) (1 << 29))#define UIF_INITIALIZED ((__force uif_t) (1 << 31))#define UIF_SUSPENDED ((__force uif_t) (1 << 30))int blocked_open;struct tasklet_struct tlet;wait_queue_head_t open_wait;wait_queue_head_t delta_msr_wait;};/** This structure describes all the operations that can be* done on the physical hardware.*/struct uart_ops {unsigned int (*tx_empty)(struct uart_port *); /* 串口的Tx FIFO缓存是否为空 */void (*set_mctrl)(struct uart_port *, unsigned int mctrl); /* 设置串口modem控制 */unsigned int (*get_mctrl)(struct uart_port *); /* 获取串口modem控制 */void (*stop_tx)(struct uart_port *); /* 禁止串口发送数据 */void (*start_tx)(struct uart_port *); /* 使能串口发送数据 */void (*send_xchar)(struct uart_port *, char ch);/* 发送xChar */void (*stop_rx)(struct uart_port *); /* 禁止串口接收数据 */void (*enable_ms)(struct uart_port *); /* 使能modem的状态信号 */void (*break_ctl)(struct uart_port *, int ctl); /* 设置break信号 */int (*startup)(struct uart_port *); /* 启动串口,应用程序打开串口设备文件时,该函数会被调用 */void (*shutdown)(struct uart_port *); /* 关闭串口,应用程序关闭串口设备文件时,该函数会被调用 */void (*set_termios)(struct uart_port *, struct ktermios *new, struct ktermios*old); /* 设置串口参数 */void (*pm)(struct uart_port *, unsigned int state,unsigned int oldstate); /* 串口电源管理 */int (*set_wake)(struct uart_port *, unsigned int state); /* */const char *(*type)(struct uart_port *); /* 返回一描述串口类型的字符串 */void (*release_port)(struct uart_port *); /* 释放串口已申请的IO端口/IO内存资源,必要时还需iounmap */int (*request_port)(struct uart_port *); /* 申请必要的IO端口/IO内存资源,必要时还可以重新映射串口端口 */void (*config_port)(struct uart_port *, int); /* 执行串口所需的自动配置 */int (*verify_port)(struct uart_port *, struct serial_struct *); /* 核实新串口的信息 */int (*ioctl)(struct uart_port *, unsigned int, unsigned long); /* IO控制 */};

二、串口驱动API

/* 功能： uart_register_driver用于将串口驱动uart_driver注册到内核(串口核心层)中，通常在模块初始化函数调用该函数。* 参数 drv：要注册的uart_driver* 返回值： 成功，返回0；否则返回错误码*/int uart_register_driver(struct uart_driver *drv) /* 功能： uart_unregister_driver用于注销我们已注册的uart_driver，通常在模块卸载函数调用该函数* 参数 drv：要注销的uart_driver* 返回值： 成功，返回0；否则返回错误码*/void uart_unregister_driver(struct uart_driver *drv)  /* 功能： uart_add_one_port用于为串口驱动添加一个串口端口，通常在探测到设备后(驱动的设备probe方法)调用该函数* 参数 drv：串口驱动* port:要添加的串口端口* 返回值： 成功，返回0；否则返回错误码*/int uart_add_one_port(struct uart_driver *drv, struct uart_port *port)  /* 功能： uart_remove_one_port用于删除一个已添加到串口驱动中的串口端口，通常在驱动卸载时调用该函数* 参数 drv： 串口驱动* port: 要删除的串口端口* 返回值： 成功，返回0；否则返回错误码*/int uart_remove_one_port(struct uart_driver *drv, struct uart_port *port)  /* 功能： uart_write_wakeup唤醒上层因向串口端口写数据而阻塞的进程，通常在串口发送中断处理函数中调用该函数* 参数 port：需要唤醒写阻塞进程的串口端口*/void uart_write_wakeup(struct uart_port *port) /* 功能： uart_suspend_port用于挂起特定的串口端口* 参数 drv： 要挂起的串口端口所属的串口驱动* port：要挂起的串口端口* 返回值： 成功返回0；否则返回错误码*/int uart_suspend_port(struct uart_driver *drv, struct uart_port *port) /* 功能： uart_resume_port用于恢复某一已挂起的串口* 参数 drv： 要恢复的串口端口所属的串口驱动* port：要恢复的串口端口* 返回值： 成功返回0；否则返回错误码*/int uart_resume_port(struct uart_driver *drv, struct uart_port *port) /* 功能： uart_get_baud_rate通过解码termios结构体来获取指定串口的波特率* 参数 port： 要获取波特率的串口端口* termios：当前期望的termios配置(包含串口波特率)* old： 以前的termios配置，可以为NULL* min： 可接受的最小波特率* max： 可接受的最大波特率* 返回值： 串口的波特率*/unsigned intuart_get_baud_rate(struct uart_port *port, struct ktermios *termios,struct ktermios *old, unsigned int min, unsigned int max) /* 功能： uart_get_divisor用于计算某一波特率的串口时钟分频数（串口波特率除数）* 参数 port：要计算时钟分频数的串口端口* baud：期望的波特率*返回值： 串口时钟分频数*/unsigned int uart_get_divisor(struct uart_port *port, unsigned int baud) /* 功能： uart_update_timeout用于更新（设置）串口FIFO超时时间* 参数 port： 要更新超时时间的串口端口* cflag：termios结构体的cflag值* baud： 串口的波特率*/void uart_update_timeout(struct uart_port *port, unsigned int cflag, unsigned int baud) /* 功能：uart_match_port用于判断两串口端口是否为同一端口* 参数 port1、port2：要判断的串口端口* 返回值：不同返回0；否则返回非0*/int uart_match_port(struct uart_port *port1, struct uart_port *port2) /* 功能： uart_console_write用于向串口端口写一控制台信息* 参数 port: 要写信息的串口端口* s: 要写的信息* count: 信息的大小* putchar: 用于向串口端口写字符的函数，该函数函数有两个参数：串口端口和要写的字符*/void uart_console_write(struct uart_port *port, const char *s,unsigned int count,void (*putchar)(struct uart_port *, int)) 

三.串口驱动例子

 

#include <linux/module.h>#include <linux/init.h>#include <linux/kernel.h> /* printk() */#include <linux/slab.h> /* kmalloc() */#include <linux/fs.h> /* everything... */#include <linux/errno.h> /* error codes */#include <linux/types.h> /* size_t */#include <linux/fcntl.h> /* O_ACCMODE */#include <asm/system.h> /* cli(), *_flags */#include <asm/uaccess.h> /* copy_*_user */#include <linux/ioctl.h>#include <linux/device.h>#include <linux/platform_device.h>#include <linux/sysrq.h>#include <linux/tty.h>#include <linux/tty_flip.h>#include <linux/serial_core.h>#include <linux/serial.h>#include <linux/delay.h>#include <linux/clk.h>#include <linux/console.h>#include <asm/io.h>#include <asm/irq.h>#include <asm/hardware.h>#include <asm/plat-s3c/regs-serial.h>#include <asm/arch/regs-gpio.h>#define DEV_NAME "gprs_uart" /* 设备名 *//* 这里将串口的主设备号设为0,则串口设备编号由内核动态分配;你也可指定串口的设备编号 */#define GPRS_UART_MAJOR 0 /* 主设备号 */#define GPRS_UART_MINOR 0 /* 次设备号 */#define GPRS_UART_FIFO_SIZE 16 /* 串口FIFO的大小 */#define RXSTAT_DUMMY_READ (0x10000000)#define MAP_SIZE (0x100) /* 要映射的串口IO内存区大小 *//* 串口发送中断号 */#define TX_IRQ(port) ((port)->irq + 1)/* 串口接收中断号 */#define RX_IRQ(port) ((port)->irq)/* 允许串口接收字符的标志 */#define tx_enabled(port) ((port)->unused[0])/* 允许串口发送字符的标志 */#define rx_enabled(port) ((port)->unused[1])/* 获取寄存器地址 */#define portaddr(port, reg) ((port)->membase + (reg))/* 读8位宽的寄存器 */#define rd_regb(port, reg) (ioread8(portaddr(port, reg)))/* 读32位宽的寄存器 */#define rd_regl(port, reg) (ioread32(portaddr(port, reg)))/* 写8位宽的寄存器 */#define wr_regb(port, reg, val) \do { iowrite8(val, portaddr(port, reg)); } while(0)/* 写32位宽的寄存器 */#define wr_regl(port, reg, val) \do { iowrite32(val, portaddr(port, reg)); } while(0)/* 禁止串口发送数据 */static void gprs_uart_stop_tx(struct uart_port *port){if (tx_enabled(port)) /* 若串口已启动发送 */{disable_irq(TX_IRQ(port)); /* 禁止发送中断 */tx_enabled(port) = 0; /* 设置串口为未启动发送 */}}/* 使能串口发送数据 */static void gprs_uart_start_tx(struct uart_port *port){if (!tx_enabled(port)) /* 若串口未启动发送 */{enable_irq(TX_IRQ(port)); /* 使能发送中断 */tx_enabled(port) = 1; /* 设置串口为已启动发送 */}}/* 禁止串口接收数据 */static void gprs_uart_stop_rx(struct uart_port *port){if (rx_enabled(port)) /* 若串口已启动接收 */{disable_irq(RX_IRQ(port)); /* 禁止接收中断 */rx_enabled(port) = 0; /* 设置串口为未启动接收 */}}/* 使能modem的状态信号 */static void gprs_uart_enable_ms(struct uart_port *port){}/* 串口的Tx FIFO缓存是否为空 */static unsigned int gprs_uart_tx_empty(struct uart_port *port){int ret = 1;unsigned long ufstat = rd_regl(port, S3C2410_UFSTAT);unsigned long ufcon = rd_regl(port, S3C2410_UFCON);if (ufcon & S3C2410_UFCON_FIFOMODE) /* 若使能了FIFO */{if ((ufstat & S3C2410_UFSTAT_TXMASK) != 0 || /* 0 <FIFO <=15 */(ufstat & S3C2410_UFSTAT_TXFULL)) /* FIFO满 */ret = 0;}else /* 若未使能了FIFO,则判断发送缓存和发送移位寄存器是否均为空 */{ret = rd_regl(port, S3C2410_UTRSTAT) & S3C2410_UTRSTAT_TXE;}return ret;}/* 获取串口modem控制,因为uart2无modem控制,所以CTS、DSR直接返回有效 */static unsigned int gprs_uart_get_mctrl(struct uart_port *port){return (TIOCM_CTS | TIOCM_DSR | TIOCM_CAR);}/* 设置串口modem控制 */static void gprs_uart_set_mctrl(struct uart_port *port, unsigned int mctrl){}/* 设置break信号 */static void gprs_uart_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;elseucon &= ~S3C2410_UCON_SBREAK;wr_regl(port, S3C2410_UCON, ucon);spin_unlock_irqrestore(&port->lock, flags);}/* 返回Rx FIFO已存多少数据 */static int gprs_uart_rx_fifocnt(unsigned long ufstat){/* 若Rx FIFO已满,返回FIFO的大小 */if (ufstat & S3C2410_UFSTAT_RXFULL)return GPRS_UART_FIFO_SIZE;/* 若FIFO未满,返回Rx FIFO已存了多少字节数据 */return (ufstat & S3C2410_UFSTAT_RXMASK) >> S3C2410_UFSTAT_RXSHIFT;}#define S3C2410_UERSTAT_PARITY (0x1000)/* 串口接收中断处理函数,获取串口接收到的数据,并将这些数据递交给行规则层 */static irqreturn_t gprs_uart_rx_chars(int irq, void *dev_id){struct uart_port *port = dev_id;struct tty_struct *tty = port->info->tty;unsigned int ufcon, ch, flag, ufstat, uerstat;int max_count = 64;/* 循环接收数据,最多一次中断接收64字节数据 */while (max_count-- > 0){ufcon = rd_regl(port, S3C2410_UFCON);ufstat = rd_regl(port, S3C2410_UFSTAT);/* 若Rx FIFO无数据了,跳出循环 */if (gprs_uart_rx_fifocnt(ufstat) == 0)break;/* 读取Rx error状态寄存器 */uerstat = rd_regl(port, S3C2410_UERSTAT);/* 读取已接受到的数据 */ch = rd_regb(port, S3C2410_URXH);/* insert the character into the buffer *//* 先将tty标志设为正常 */flag = TTY_NORMAL;/* 递增接收字符计数器 */port->icount.rx++;/* 判断是否存在Rx error* if (unlikely(uerstat & S3C2410_UERSTAT_ANY))等同于* if (uerstat & S3C2410_UERSTAT_ANY)* 只是unlikely表示uerstat & S3C2410_UERSTAT_ANY的值为假的可能性大一些* 另外还有一个likely(value)表示value的值为真的可能性更大一些*/if (unlikely(uerstat & S3C2410_UERSTAT_ANY)){/* 若break错误,递增icount.brk计算器 */if (uerstat & S3C2410_UERSTAT_BREAK){port->icount.brk++;if (uart_handle_break(port))goto ignore_char;}/* 若frame错误,递增icount.frame计算器 */if (uerstat & S3C2410_UERSTAT_FRAME)port->icount.frame++;/* 若overrun错误,递增icount.overrun计算器 */if (uerstat & S3C2410_UERSTAT_OVERRUN)port->icount.overrun++;/* 查看我们是否关心该Rx error* port->read_status_mask保存着我们感兴趣的Rx error status*/uerstat &= port->read_status_mask;/* 若我们关心该Rx error,则将flag设置为对应的error flag */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;}/* 处理sys字符 */if (uart_handle_sysrq_char(port, ch))goto ignore_char;/* 将接收到的字符插入到tty设备的flip缓冲 */uart_insert_char(port, uerstat, S3C2410_UERSTAT_OVERRUN, ch, flag);ignore_char:continue;}/* 刷新tty设备的flip缓冲,将接受到的数据传给行规则层 */tty_flip_buffer_push(tty);return IRQ_HANDLED;}/* 串口发送中断处理函数,将用户空间的数据(保存在环形缓冲xmit里)发送出去 */static irqreturn_t gprs_uart_tx_chars(int irq, void *dev_id){struct uart_port *port = dev_id;struct circ_buf *xmit = &port->info->xmit; /* 获取环线缓冲 */int count = 256;/* 若设置了xChar字符 */if (port->x_char){/* 将该xChar发送出去 */wr_regb(port, S3C2410_UTXH, port->x_char);/* 递增发送计数 */port->icount.tx++;/* 清除xChar */port->x_char = 0;/* 退出中断处理 */goto out;}/* 如果没有更多的字符需要发送(环形缓冲为空)，* 或者uart Tx已停止，* 则停止uart并退出中断处理函数*/if (uart_circ_empty(xmit) || uart_tx_stopped(port)){gprs_uart_stop_tx(port);goto out;}/* 循环发送数据,直到环形缓冲为空,最多一次中断发送256字节数据 */while (!uart_circ_empty(xmit) && count-- > 0){/* 若Tx FIFO已满,退出循环 */if (rd_regl(port, S3C2410_UFSTAT) & S3C2410_UFSTAT_TXFULL)break;/* 将要发送的数据写入Tx FIFO */wr_regb(port, S3C2410_UTXH, xmit->buf[xmit->tail]);/* 移向循环缓冲中下一要发送的数据 */xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);port->icount.tx++;}/* 如果环形缓冲区中剩余的字符少于WAKEUP_CHARS，唤醒上层 */if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)uart_write_wakeup(port);/* 如果环形缓冲为空，则停止发送 */if (uart_circ_empty(xmit))gprs_uart_stop_tx(port);out:return IRQ_HANDLED;}/* 启动串口端口,在打开该驱动的设备文件时会调用该函数来申请串口中断,并设置串口为可接受,也可发送 */static int gprs_uart_startup(struct uart_port *port){unsigned long flags;int ret;const char *portname = to_platform_device(port->dev)->name;/* 设置串口为不可接受,也不可发送 */rx_enabled(port) = 0;tx_enabled(port) = 0;spin_lock_irqsave(&port->lock, flags);/* 申请接收中断 */ret = request_irq(RX_IRQ(port), gprs_uart_rx_chars, 0, portname, port);if (ret != 0){printk(KERN_ERR "cannot get irq %d\n", RX_IRQ(port));return ret;}/* 设置串口为允许接收 */rx_enabled(port) = 1;/* 申请发送中断 */ret = request_irq(TX_IRQ(port), gprs_uart_tx_chars, 0, portname, port);if (ret){printk(KERN_ERR "cannot get irq %d\n", TX_IRQ(port));rx_enabled(port) = 0;free_irq(RX_IRQ(port), port);goto err;}/* 设置串口为允许发送 */tx_enabled(port) = 1;err:spin_unlock_irqrestore(&port->lock, flags);return ret;}/* 关闭串口,在关闭驱动的设备文件时会调用该函数,释放串口中断 */static void gprs_uart_shutdown(struct uart_port *port){rx_enabled(port) = 0; /* 设置串口为不允许接收 */free_irq(RX_IRQ(port), port); /* 释放接收中断 */tx_enabled(port) = 0; /* 设置串口为不允许发送 */free_irq(TX_IRQ(port), port); /* 释放发送中断 */}/* 设置串口参数 */static void gprs_uart_set_termios(struct uart_port *port,  struct ktermios *termios,  struct ktermios *old){unsigned long flags;unsigned int baud, quot;unsigned int ulcon, ufcon = 0;/* 不支持moden控制信号线* HUPCL: 关闭时挂断moden* CMSPAR: mark or space (stick) parity* CLOCAL: 忽略任何moden控制线*/termios->c_cflag &= ~(HUPCL | CMSPAR);termios->c_cflag |= CLOCAL;/* 获取用户设置的串口波特率,并计算分频数(串口波特率除数quot) */baud = uart_get_baud_rate(port, termios, old, 0, 115200*8);if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)quot = port->custom_divisor;elsequot = port->uartclk / baud / 16 - 1;/* 设置数据字长 */switch (termios->c_cflag & CSIZE){case CS5:ulcon = S3C2410_LCON_CS5;break;case CS6:ulcon = S3C2410_LCON_CS6;break;case CS7:ulcon = S3C2410_LCON_CS7;break;case CS8:default:ulcon = S3C2410_LCON_CS8;break;}/* 是否要求设置两个停止位(CSTOPB) */if (termios->c_cflag & CSTOPB)ulcon |= S3C2410_LCON_STOPB;/* 是否使用奇偶检验 */if (termios->c_cflag & PARENB){if (termios->c_cflag & PARODD) /* 奇校验 */ulcon |= S3C2410_LCON_PODD;else /* 偶校验 */ulcon |= S3C2410_LCON_PEVEN;}else /* 无校验 */{ulcon |= S3C2410_LCON_PNONE;}if (port->fifosize > 1)ufcon |= S3C2410_UFCON_FIFOMODE | S3C2410_UFCON_RXTRIG8;spin_lock_irqsave(&port->lock, flags);/* 设置FIFO控制寄存器、线控制寄存器和波特率除数寄存器 */wr_regl(port, S3C2410_UFCON, ufcon);wr_regl(port, S3C2410_ULCON, ulcon);wr_regl(port, S3C2410_UBRDIV, quot);/* 更新串口FIFO的超时时限 */uart_update_timeout(port, termios->c_cflag, baud);/* 设置我们感兴趣的Rx error */port->read_status_mask = S3C2410_UERSTAT_OVERRUN;if (termios->c_iflag & INPCK)port->read_status_mask |= S3C2410_UERSTAT_FRAME | S3C2410_UERSTAT_PARITY;/* 设置我们忽略的Rx error */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;/* 若未设置CREAD(使用接收器),则忽略所有Rx error*/if ((termios->c_cflag & CREAD) == 0)port->ignore_status_mask |= RXSTAT_DUMMY_READ;spin_unlock_irqrestore(&port->lock, flags);}/* 获取串口类型 */static const char *gprs_uart_type(struct uart_port *port){/* 返回描述串口类型的字符串指针 */return port->type == PORT_S3C2410 ? "gprs_uart:s3c2410_uart2" : NULL;}/* 申请串口一些必要的资源,如IO端口/IO内存资源,必要时还可以重新映射串口端口 */static int gprs_uart_request_port(struct uart_port *port){struct resource *res;const char *name = to_platform_device(port->dev)->name;/* request_mem_region请求分配IO内存,从开始port->mapbase,大小MAP_SIZE* port->mapbase保存当前串口的寄存器基地址(物理)* uart2: 0x50008000*/res = request_mem_region(port->mapbase, MAP_SIZE, name);if (res == NULL){printk(KERN_ERR"request_mem_region error: %p\n", res);return -EBUSY;}return 0;}/* 释放串口已申请的IO端口/IO内存资源,必要时还需iounmap */static void gprs_uart_release_port(struct uart_port *port){/* 释放已分配IO内存 */release_mem_region(port->mapbase, MAP_SIZE);}/* 执行串口所需的自动配置 */static void gprs_uart_config_port(struct uart_port *port, int flags){int retval;/* 请求串口 */retval = gprs_uart_request_port(port);/* 设置串口类型 */if (flags & UART_CONFIG_TYPE && retval == 0)port->type = PORT_S3C2410;}/* The UART operations structure */static struct uart_ops gprs_uart_ops = {.start_tx = gprs_uart_start_tx, /* Start transmitting */.stop_tx = gprs_uart_stop_tx, /* Stop transmission */.stop_rx = gprs_uart_stop_rx, /* Stop reception */.enable_ms = gprs_uart_enable_ms, /* Enable modem status signals */.tx_empty = gprs_uart_tx_empty, /* Transmitter busy? */.get_mctrl = gprs_uart_get_mctrl, /* Get modem control */.set_mctrl = gprs_uart_set_mctrl, /* Set modem control */.break_ctl = gprs_uart_break_ctl, /* Set break signal */.startup = gprs_uart_startup, /* App opens GPRS_UART */.shutdown = gprs_uart_shutdown, /* App closes GPRS_UART */.set_termios = gprs_uart_set_termios, /* Set termios */.type = gprs_uart_type, /* Get UART type */.request_port = gprs_uart_request_port, /* Claim resources associated with a GPRS_UART port */.release_port = gprs_uart_release_port, /* Release resources associated with a GPRS_UART port */.config_port = gprs_uart_config_port, /* Configure when driver adds a GPRS_UART port */};/* Uart driver for GPRS_UART */static struct uart_driver gprs_uart_driver = {.owner = THIS_MODULE, /* Owner */.driver_name = DEV_NAME, /* Driver name */.dev_name = DEV_NAME, /* Device node name */.major = GPRS_UART_MAJOR, /* Major number */.minor = GPRS_UART_MINOR, /* Minor number start */.nr = 1, /* Number of UART ports */};/* Uart port for GPRS_UART port */static struct uart_port gprs_uart_port = {.irq = IRQ_S3CUART_RX2, /* IRQ */.fifosize = GPRS_UART_FIFO_SIZE, /* Size of the FIFO */.iotype = UPIO_MEM, /* IO memory */.flags = UPF_BOOT_AUTOCONF, /* UART port flag */.ops = &gprs_uart_ops, /* UART operations */.line = 0, /* UART port number */.lock = __SPIN_LOCK_UNLOCKED(gprs_uart_port.lock),};/* 初始化指定串口端口 */static int gprs_uart_init_port(struct uart_port *port, struct platform_device *platdev){unsigned long flags;unsigned int gphcon;if (platdev == NULL)return -ENODEV;port->dev = &platdev->dev;/* 设置串口波特率时钟频率 */port->uartclk = clk_get_rate(clk_get(&platdev->dev, "pclk"));/* 设置串口的寄存器基地址(物理): 0x50008000 */port->mapbase = S3C2410_PA_UART2;/* 设置当前串口的寄存器基地址(虚拟): 0xF5008000 */port->membase = S3C24XX_VA_UART + (S3C2410_PA_UART2 - S3C24XX_PA_UART);spin_lock_irqsave(&port->lock, flags);wr_regl(port, S3C2410_UCON, S3C2410_UCON_DEFAULT);wr_regl(port, S3C2410_ULCON, S3C2410_LCON_CS8 | S3C2410_LCON_PNONE);wr_regl(port, S3C2410_UFCON, S3C2410_UFCON_FIFOMODE| S3C2410_UFCON_RXTRIG8 | S3C2410_UFCON_RESETBOTH);/* 将I/O port H的gph6和gph7设置为TXD2和RXD2 */gphcon = readl(S3C2410_GPHCON);gphcon &= ~((0x5) << 12);writel(gphcon, S3C2410_GPHCON);spin_unlock_irqrestore(&port->lock, flags);return 0;}/* Platform driver probe */static int __init gprs_uart_probe(struct platform_device *dev){int ret;/* 初始化串口 */ret = gprs_uart_init_port(&gprs_uart_port, dev);if (ret < 0){printk(KERN_ERR"gprs_uart_probe: gprs_uart_init_port error: %d\n", ret);return ret;}/* 添加串口 */ret = uart_add_one_port(&gprs_uart_driver, &gprs_uart_port);if (ret < 0){printk(KERN_ERR"gprs_uart_probe: uart_add_one_port error: %d\n", ret);return ret;}/* 将串口uart_port结构体保存在platform_device->dev->driver_data中 */platform_set_drvdata(dev, &gprs_uart_port);return 0;}/* Called when the platform driver is unregistered */static int gprs_uart_remove(struct platform_device *dev){platform_set_drvdata(dev, NULL);/* 移除串口 */uart_remove_one_port(&gprs_uart_driver, &gprs_uart_port);return 0;}/* Suspend power management event */static int gprs_uart_suspend(struct platform_device *dev, pm_message_t state){uart_suspend_port(&gprs_uart_driver, &gprs_uart_port);return 0;}/* Resume after a previous suspend */static int gprs_uart_resume(struct platform_device *dev){uart_resume_port(&gprs_uart_driver, &gprs_uart_port);return 0;}/* Platform driver for GPRS_UART */static struct platform_driver gprs_plat_driver = {.probe = gprs_uart_probe, /* Probe method */.remove = __exit_p(gprs_uart_remove), /* Detach method */.suspend = gprs_uart_suspend, /* Power suspend */.resume = gprs_uart_resume, /* Resume after a suspend */.driver = {.owner = THIS_MODULE,.name = DEV_NAME, /* Driver name */},};/* Platform device for GPRS_UART */struct platform_device *gprs_plat_device;static int __init gprs_init_module(void){int retval;/* Register uart_driver for GPRS_UART */retval = uart_register_driver(&gprs_uart_driver);if (0 != retval){printk(KERN_ERR "gprs_init_module: can't register the GPRS_UART driver %d\n",retval);return retval;}/* Register platform device for GPRS_UART. Usually calledduring architecture-specific setup */gprs_plat_device = platform_device_register_simple(DEV_NAME, 0, NULL, 0);if (IS_ERR(gprs_plat_device)){retval = PTR_ERR(gprs_plat_device);printk(KERN_ERR "gprs_init_module: can't register platform device %d\n", retval);goto fail_reg_plat_dev;}/* Announce a matching driver for the platformdevices registered above */retval = platform_driver_register(&gprs_plat_driver);if (0 != retval){printk(KERN_ERR "gprs_init_module: can't register platform driver %d\n", retval);goto fail_reg_plat_drv;}return 0; /* succeed */fail_reg_plat_drv:platform_device_unregister(gprs_plat_device);fail_reg_plat_dev:uart_unregister_driver(&gprs_uart_driver);return retval;}static void __exit gprs_exit_module(void){/* The order of unregistration is important. Unregistering theUART driver before the platform driver will crash the system *//* Unregister the platform driver */platform_driver_unregister(&gprs_plat_driver);/* Unregister the platform devices */platform_device_unregister(gprs_plat_device);/* Unregister the GPRS_UART driver */uart_unregister_driver(&gprs_uart_driver);}module_init(gprs_init_module);module_exit(gprs_exit_module);MODULE_AUTHOR("");MODULE_LICENSE("Dual BSD/GPL");