Linux串口驱动分析初始化

<pre name="code" class="cpp">/*** uart分析** 其实串口分析就两个重要的文件: S3c2440.c  Samsung.c** **//*1. 首先从Samsung.c的模块初始化函数看起*/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;
}/*参数是需要程序员自己定义 */
/** s3c2440.c **/static struct s3c24xx_uart_info s3c2440_uart_inf = {.name     = "Samsung S3C2440 UART",.type       = PORT_S3C2440,                //端口类型.fifosize = 64,                      //FIFO缓冲区大小.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,
};/*platform 驱动定义： s3c2440_serial_driver*/
static struct platform_driver s3c2440_serial_driver = {.probe      = s3c2440_serial_probe,                //匹配后设备调用.remove        = __devexit_p(s3c24xx_serial_remove),.driver       = {.name   = "s3c2440-uart",        //驱动的名字.owner   = THIS_MODULE,},
};/*分析uart_register_driver函数*/
/* 这个函数的主要作用是初始化tty_driver结构体。 其实tty_driver的主要成员都是通过传进来的参数drv赋值的* 其次是初始化uart_driver中的uart_state成员。* * uart_state是一个结构体包含了tty_port和uart_port。 而uart_port主要是和硬件相关。 其实每一个串口都对应一个uart_port结构* 这里只初始化了tty_port结构。而uart_port是在等设备匹配上后在设备的ops中的probe函数中初始化*/
int uart_register_driver(struct uart_driver *drv)
{/** Maybe we should be using a slab cache for this, especially if* we have a large number of ports to handle.*/drv->state = kzalloc(sizeof(struct uart_state) * drv->nr, GFP_KERNEL);if (!drv->state)goto out;normal = alloc_tty_driver(drv->nr);if (!normal)goto out_kfree;drv->tty_driver = normal;normal->owner        = drv->owner;normal->driver_name = drv->driver_name;normal->name      = drv->dev_name;normal->major        = drv->major;normal->minor_start = drv->minor;normal->type        = TTY_DRIVER_TYPE_SERIAL;normal->subtype        = SERIAL_TYPE_NORMAL;normal->init_termios   = tty_std_termios;normal->init_termios.c_cflag = B9600 | CS8 | CREAD | HUPCL | CLOCAL;normal->init_termios.c_ispeed = normal->init_termios.c_ospeed = 9600;normal->flags        = TTY_DRIVER_REAL_RAW | TTY_DRIVER_DYNAMIC_DEV;normal->driver_state    = drv;tty_set_operations(normal, &uart_ops);/** Initialise the UART state(s).*/for (i = 0; i < drv->nr; i++) {struct uart_state *state = drv->state + i;struct tty_port *port = &state->port;tty_port_init(port);port->ops = &uart_port_ops;port->close_delay     = 500;  /* .5 seconds */port->closing_wait    = 30000;  /* 30 seconds */tasklet_init(&state->tlet, uart_tasklet_action,(unsigned long)state);}retval = tty_register_driver(normal);
}/* 当设备与驱动匹配后，会调用此函数。**  probe函数一般就是做的硬件相关的初始化。*  *  其实uart_port的初始化也是通过s3c24xx_uart_port来初始化的。* */
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);/*取得相应的端口*/ourport = &s3c24xx_serial_ports[probe_index];probe_index++;dbg("%s: initialising port %p...\n", __func__, ourport);/*初始化端口*/ret = s3c24xx_serial_init_port(ourport, info, dev);if (ret < 0)goto probe_err;dbg("%s: adding port\n", __func__);/*这个函数的主要作用是： 将uart_port和uart_driver关联起来*/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;
}/** 端口初始化函数* */
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;/*获取设备的资源，详细解析见下面*/cfg = s3c24xx_dev_to_cfg(&platdev->dev);if (port->mapbase != 0)return 0;/*判断是否大于总数4个*/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;}port->dev = &platdev->dev;ourport->info    = info;/*初始化port的大小 = 64*/ourport->port.fifosize = info->fifosize;dbg("s3c24xx_serial_init_port: %p (hw %d)...\n", port, cfg->hwport);port->uartclk = 1;/*判断是否开启流控*/if (cfg->uart_flags & UPF_CONS_FLOW) {dbg("s3c24xx_serial_init_port: enabling flow control\n");port->flags |= UPF_CONS_FLOW;}/*获取uart资源*/res = platform_get_resource(platdev, IORESOURCE_MEM, 0);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);/*初始化基地址等*/port->mapbase = res->start;port->membase = S3C_VA_UART + (res->start & 0xfffff);ret = platform_get_irq(platdev, 0);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);if (ret > 0)ourport->tx_irq = ret;/*获取时钟*/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;
}#define s3c24xx_dev_to_cfg(__dev) (struct s3c2410_uartcfg *)((__dev)->platform_data)
/** cfg = s3c24xx_dev_to_cfg(&platdev->dev)* * 那么cfg到底是如何获得?** 搜索s3c2410_uartcfg得到：*/#define UCON S3C2410_UCON_DEFAULT | S3C2410_UCON_UCLK
#define ULCON S3C2410_LCON_CS8 | S3C2410_LCON_PNONE | S3C2410_LCON_STOPB
#define UFCON S3C2410_UFCON_RXTRIG8 | S3C2410_UFCON_FIFOMODEstatic struct s3c2410_uartcfg smdk2440_uartcfgs[] __initdata = {[0] = {.hwport         = 0,.flags         = 0,.ucon      = 0x3c5,.ulcon         = 0x03,.ufcon      = 0x51,},[1] = {.hwport       = 1,.flags         = 0,.ucon      = 0x3c5,.ulcon         = 0x03,.ufcon      = 0x51,},[2] = {.hwport       = 2,.flags         = 0,.ucon      = 0x3c5,.ulcon         = 0x43,.ufcon      = 0x51,}};void __init s3c24xx_init_uarts(struct s3c2410_uartcfg *cfg, int no)
{if (cpu == NULL)return;if (cpu->init_uarts == NULL) {printk(KERN_ERR "s3c24xx_init_uarts: cpu has no uart init\n");} else(cpu->init_uarts)(cfg, no);
}/*初始化系统上的串口资源*/
void __init s3c24xx_init_uartdevs(char *name,struct s3c24xx_uart_resources *res,struct s3c2410_uartcfg *cfg, int no)
{struct platform_device *platdev;struct s3c2410_uartcfg *cfgptr = uart_cfgs;struct s3c24xx_uart_resources *resp;int uart;memcpy(cfgptr, cfg, sizeof(struct s3c2410_uartcfg) * no);for (uart = 0; uart < no; uart++, cfg++, cfgptr++) {platdev = s3c24xx_uart_src[cfgptr->hwport];resp = res + cfgptr->hwport;s3c24xx_uart_devs[uart] = platdev;platdev->name = name;platdev->resource = resp->resources;platdev->num_resources = resp->nr_resources;/*从这里获取platform*/platdev->dev.platform_data = cfgptr;}nr_uarts = no;
}/*uart 所对应的资源 platform_get_resourced调用**/
/* Serial port registrations */static struct resource s3c2410_uart0_resource[] = {[0] = {.start = S3C2410_PA_UART0,.end   = S3C2410_PA_UART0 + 0x3fff,.flags = IORESOURCE_MEM,},[1] = {.start = IRQ_S3CUART_RX0,.end   = IRQ_S3CUART_ERR0,.flags = IORESOURCE_IRQ,}
};static struct resource s3c2410_uart1_resource[] = {[0] = {.start = S3C2410_PA_UART1,.end   = S3C2410_PA_UART1 + 0x3fff,.flags = IORESOURCE_MEM,},[1] = {.start = IRQ_S3CUART_RX1,.end   = IRQ_S3CUART_ERR1,.flags = IORESOURCE_IRQ,}
};static struct resource s3c2410_uart2_resource[] = {[0] = {.start = S3C2410_PA_UART2,.end   = S3C2410_PA_UART2 + 0x3fff,.flags = IORESOURCE_MEM,},[1] = {.start = IRQ_S3CUART_RX2,.end   = IRQ_S3CUART_ERR2,.flags = IORESOURCE_IRQ,}
};static struct resource s3c2410_uart3_resource[] = {[0] = {.start = S3C2443_PA_UART3,.end   = S3C2443_PA_UART3 + 0x3fff,.flags = IORESOURCE_MEM,},[1] = {.start = IRQ_S3CUART_RX3,.end   = IRQ_S3CUART_ERR3,.flags = IORESOURCE_IRQ,},
};struct s3c24xx_uart_resources s3c2410_uart_resources[] __initdata = {[0] = {.resources  = s3c2410_uart0_resource,.nr_resources = ARRAY_SIZE(s3c2410_uart0_resource),},[1] = {.resources  = s3c2410_uart1_resource,.nr_resources = ARRAY_SIZE(s3c2410_uart1_resource),},[2] = {.resources  = s3c2410_uart2_resource,.nr_resources = ARRAY_SIZE(s3c2410_uart2_resource),},[3] = {.resources  = s3c2410_uart3_resource,.nr_resources = ARRAY_SIZE(s3c2410_uart3_resource),},
};总结： 修改驱动需要设计的数据结构1. uart_driver:用于初始化tty_driver
2. s3c24xx_uart_port: 用于初始化uart_port
3. s3c24xx_serial_ops: 硬件的操作集
4. s3c24xx_uart_info： 用于初始化uart_port其实也就是：编写S3c2440.c这个串口文件。

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