上一節我們分析了bootoader中傳過來的cmdline中的命令是如何解析並執行的。
同時也是對bootloader中傳過來的console進行了記錄。
console也就是我們所說的控制檯，可以是任何常見的輸出設備，比如serial，比如framebuffer，比如網口。
本節主要以最常見的串口爲例說明。
如果有搜索過內核代碼，可以看到絕大多數的console都是串口設備。
所以內核對用作串口程序進行了進一步的封裝，抽象出的serial_core.c文件中，對console的註冊留有了接口。
console的註冊函數是register_console，這個函數我們後面說。
void register_console(struct console *newcon)
這裏我們先簡單看一下串口驅動。
這裏以三星的爲例，這裏不會詳細分析代碼，只會說一下串口驅動的架構。
串口驅動主要由下面這個來表示
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;
};
三星的實現如下，這裏的console是console使用的
static struct uart_driver s3c24xx_uart_drv = {
.owner = THIS_MODULE,
.driver_name = "s3c2410_serial",
.nr = CONFIG_SERIAL_SAMSUNG_UARTS,
.cons = S3C24XX_SERIAL_CONSOLE,
.dev_name = S3C24XX_SERIAL_NAME,
.major = S3C24XX_SERIAL_MAJOR,
.minor = S3C24XX_SERIAL_MINOR,
};
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,
.data = &s3c24xx_uart_drv,
};
#define S3C24XX_SERIAL_NAME "ttySAC"
#define S3C24XX_SERIAL_MAJOR 204
#define S3C24XX_SERIAL_MINOR 64
/* 串口設備數量由具體的CPU決定 */
CONFIG_SERIAL_SAMSUNG_UARTS
這裏我們只關注名字爲"ttySAC"，所以我們uboot的傳參就是console = "ttySACx"
後面的這個x，內核解析爲了index。
接下來再看一下一個uart端口是如何描述
內核抽象出了公共的部分。
struct uart_port {
spinlock_t lock; /* port lock */
unsigned long iobase; /* in/out[bwl] */
unsigned char __iomem *membase; /* read/write[bwl] */
unsigned int (*serial_in)(struct uart_port *, int);
void (*serial_out)(struct uart_port *, int, int);
void (*set_termios)(struct uart_port *,
struct ktermios *new,
struct ktermios *old);
void (*set_ldisc)(struct uart_port *,
struct ktermios *);
unsigned int (*get_mctrl)(struct uart_port *);
void (*set_mctrl)(struct uart_port *, unsigned int);
unsigned int (*get_divisor)(struct uart_port *,
unsigned int baud,
unsigned int *frac);
void (*set_divisor)(struct uart_port *,
unsigned int baud,
unsigned int quot,
unsigned int quot_frac);
int (*startup)(struct uart_port *port);
void (*shutdown)(struct uart_port *port);
void (*throttle)(struct uart_port *port);
void (*unthrottle)(struct uart_port *port);
int (*handle_irq)(struct uart_port *);
void (*pm)(struct uart_port *, unsigned int state,
unsigned int old);
void (*handle_break)(struct uart_port *);
int (*rs485_config)(struct uart_port *,
struct serial_rs485 *rs485);
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 quirks; /* internal quirks */
#define UPIO_PORT (SERIAL_IO_PORT) /* 8b I/O port access */
#define UPIO_HUB6 (SERIAL_IO_HUB6) /* Hub6 ISA card */
#define UPIO_MEM (SERIAL_IO_MEM) /* driver-specific */
#define UPIO_MEM32 (SERIAL_IO_MEM32) /* 32b little endian */
#define UPIO_AU (SERIAL_IO_AU) /* Au1x00 and RT288x type IO */
#define UPIO_TSI (SERIAL_IO_TSI) /* Tsi108/109 type IO */
#define UPIO_MEM32BE (SERIAL_IO_MEM32BE) /* 32b big endian */
#define UPIO_MEM16 (SERIAL_IO_MEM16) /* 16b little endian */
/* quirks must be updated while holding port mutex */
#define UPQ_NO_TXEN_TEST BIT(0)
unsigned int read_status_mask; /* driver specific */
unsigned int ignore_status_mask; /* driver specific */
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
/* flags must be updated while holding port mutex */
upf_t flags;
/*
* These flags must be equivalent to the flags defined in
* include/uapi/linux/tty_flags.h which are the userspace definitions
* assigned from the serial_struct flags in uart_set_info()
* [for bit definitions in the UPF_CHANGE_MASK]
*
* Bits [0..UPF_LAST_USER] are userspace defined/visible/changeable
* The remaining bits are serial-core specific and not modifiable by
* userspace.
*/
#define UPF_FOURPORT ((__force upf_t) ASYNC_FOURPORT /* 1 */ )
#define UPF_SAK ((__force upf_t) ASYNC_SAK /* 2 */ )
#define UPF_SPD_HI ((__force upf_t) ASYNC_SPD_HI /* 4 */ )
#define UPF_SPD_VHI ((__force upf_t) ASYNC_SPD_VHI /* 5 */ )
#define UPF_SPD_CUST ((__force upf_t) ASYNC_SPD_CUST /* 0x0030 */ )
#define UPF_SPD_WARP ((__force upf_t) ASYNC_SPD_WARP /* 0x1010 */ )
#define UPF_SPD_MASK ((__force upf_t) ASYNC_SPD_MASK /* 0x1030 */ )
#define UPF_SKIP_TEST ((__force upf_t) ASYNC_SKIP_TEST /* 6 */ )
#define UPF_AUTO_IRQ ((__force upf_t) ASYNC_AUTO_IRQ /* 7 */ )
#define UPF_HARDPPS_CD ((__force upf_t) ASYNC_HARDPPS_CD /* 11 */ )
#define UPF_SPD_SHI ((__force upf_t) ASYNC_SPD_SHI /* 12 */ )
#define UPF_LOW_LATENCY ((__force upf_t) ASYNC_LOW_LATENCY /* 13 */ )
#define UPF_BUGGY_UART ((__force upf_t) ASYNC_BUGGY_UART /* 14 */ )
#define UPF_MAGIC_MULTIPLIER ((__force upf_t) ASYNC_MAGIC_MULTIPLIER /* 16 */ )
#define UPF_NO_THRE_TEST ((__force upf_t) (1 << 19))
/* Port has hardware-assisted h/w flow control */
#define UPF_AUTO_CTS ((__force upf_t) (1 << 20))
#define UPF_AUTO_RTS ((__force upf_t) (1 << 21))
#define UPF_HARD_FLOW ((__force upf_t) (UPF_AUTO_CTS | UPF_AUTO_RTS))
/* Port has hardware-assisted s/w flow control */
#define UPF_SOFT_FLOW ((__force upf_t) (1 << 22))
#define UPF_CONS_FLOW ((__force upf_t) (1 << 23))
#define UPF_SHARE_IRQ ((__force upf_t) (1 << 24))
#define UPF_EXAR_EFR ((__force upf_t) (1 << 25))
#define UPF_BUG_THRE ((__force upf_t) (1 << 26))
/* 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 0x17fff
#define UPF_CHANGE_MASK ((__force upf_t) __UPF_CHANGE_MASK)
#define UPF_USR_MASK ((__force upf_t) (UPF_SPD_MASK|UPF_LOW_LATENCY))
#if __UPF_CHANGE_MASK > ASYNC_FLAGS
#error Change mask not equivalent to userspace-visible bit defines
#endif
/*
* Must hold termios_rwsem, port mutex and port lock to change;
* can hold any one lock to read.
*/
upstat_t status;
#define UPSTAT_CTS_ENABLE ((__force upstat_t) (1 << 0))
#define UPSTAT_DCD_ENABLE ((__force upstat_t) (1 << 1))
#define UPSTAT_AUTORTS ((__force upstat_t) (1 << 2))
#define UPSTAT_AUTOCTS ((__force upstat_t) (1 << 3))
#define UPSTAT_AUTOXOFF ((__force upstat_t) (1 << 4))
#define UPSTAT_SYNC_FIFO ((__force upstat_t) (1 << 5))
int hw_stopped; /* sw-assisted CTS flow state */
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 */
unsigned int minor;
resource_size_t mapbase; /* for ioremap */
resource_size_t mapsize;
struct device *dev; /* parent device */
unsigned char hub6; /* this should be in the 8250 driver */
unsigned char suspended;
unsigned char unused[2];
const char *name; /* port name */
struct attribute_group *attr_group; /* port specific attributes */
const struct attribute_group **tty_groups; /* all attributes (serial core use only) */
struct serial_rs485 rs485;
void *private_data; /* generic platform data pointer */
};
不同廠家在內核的基礎上繼續封裝實現自己獨特的部分。
struct s3c24xx_uart_port {
unsigned char rx_claimed;
unsigned char tx_claimed;
unsigned int pm_level;
unsigned long baudclk_rate;
unsigned int min_dma_size;
unsigned int rx_irq;
unsigned int tx_irq;
unsigned int tx_in_progress;
unsigned int tx_mode;
unsigned int rx_mode;
struct s3c24xx_uart_info *info;
struct clk *clk;
struct clk *baudclk;
struct uart_port port;
struct s3c24xx_serial_drv_data *drv_data;
/* reference to platform data */
struct s3c2410_uartcfg *cfg;
struct s3c24xx_uart_dma *dma;
#ifdef CONFIG_ARM_S3C24XX_CPUFREQ
struct notifier_block freq_transition;
#endif
};
三星一個SOC最多4個串口，所以這裏根據配置最多定義了4個。
這裏我們關注一個點，line，爲串口的硬件編號，和次序一樣。
#define __PORT_LOCK_UNLOCKED(i) \
__SPIN_LOCK_UNLOCKED(s3c24xx_serial_ports[i].port.lock)
static struct s3c24xx_uart_port
s3c24xx_serial_ports[CONFIG_SERIAL_SAMSUNG_UARTS] = {
[0] = {
.port = {
.lock = __PORT_LOCK_UNLOCKED(0),
.iotype = UPIO_MEM,
.uartclk = 0,
.fifosize = 16,
.ops = &s3c24xx_serial_ops,
.flags = UPF_BOOT_AUTOCONF,
.line = 0,
}
},
[1] = {
.port = {
.lock = __PORT_LOCK_UNLOCKED(1),
.iotype = UPIO_MEM,
.uartclk = 0,
.fifosize = 16,
.ops = &s3c24xx_serial_ops,
.flags = UPF_BOOT_AUTOCONF,
.line = 1,
}
},
#if CONFIG_SERIAL_SAMSUNG_UARTS > 2
[2] = {
.port = {
.lock = __PORT_LOCK_UNLOCKED(2),
.iotype = UPIO_MEM,
.uartclk = 0,
.fifosize = 16,
.ops = &s3c24xx_serial_ops,
.flags = UPF_BOOT_AUTOCONF,
.line = 2,
}
},
#endif
#if CONFIG_SERIAL_SAMSUNG_UARTS > 3
[3] = {
.port = {
.lock = __PORT_LOCK_UNLOCKED(3),
.iotype = UPIO_MEM,
.uartclk = 0,
.fifosize = 16,
.ops = &s3c24xx_serial_ops,
.flags = UPF_BOOT_AUTOCONF,
.line = 3,
}
}
#endif
};
#undef __PORT_LOCK_UNLOCKED
其它標誌之類比較常見，但其實我們都知道，重點在操作方法，也就是ops。
這是一個很複雜的結構，裏面函數很多，但基本都是硬件操作相關的。這裏就不再細看。
static struct uart_ops s3c24xx_serial_ops = {
.pm = s3c24xx_serial_pm,
.tx_empty = s3c24xx_serial_tx_empty,
.get_mctrl = s3c24xx_serial_get_mctrl,
.set_mctrl = s3c24xx_serial_set_mctrl,
.stop_tx = s3c24xx_serial_stop_tx,
.start_tx = s3c24xx_serial_start_tx,
.stop_rx = s3c24xx_serial_stop_rx,
.break_ctl = s3c24xx_serial_break_ctl,
.startup = s3c24xx_serial_startup,
.shutdown = s3c24xx_serial_shutdown,
.set_termios = s3c24xx_serial_set_termios,
.type = s3c24xx_serial_type,
.release_port = s3c24xx_serial_release_port,
.request_port = s3c24xx_serial_request_port,
.config_port = s3c24xx_serial_config_port,
.verify_port = s3c24xx_serial_verify_port,
#if defined(CONFIG_SERIAL_SAMSUNG_CONSOLE) && defined(CONFIG_CONSOLE_POLL)
.poll_get_char = s3c24xx_serial_get_poll_char,
.poll_put_char = s3c24xx_serial_put_poll_char,
#endif
};
這裏我們看一下驅動入口，
static const struct platform_device_id s3c24xx_serial_driver_ids[] = {
{
.name = "s3c2410-uart",
.driver_data = S3C2410_SERIAL_DRV_DATA,
}, {
.name = "s3c2412-uart",
.driver_data = S3C2412_SERIAL_DRV_DATA,
}, {
.name = "s3c2440-uart",
.driver_data = S3C2440_SERIAL_DRV_DATA,
}, {
.name = "s3c6400-uart",
.driver_data = S3C6400_SERIAL_DRV_DATA,
}, {
.name = "s5pv210-uart",
.driver_data = S5PV210_SERIAL_DRV_DATA,
}, {
.name = "exynos4210-uart",
.driver_data = EXYNOS4210_SERIAL_DRV_DATA,
}, {
.name = "exynos5433-uart",
.driver_data = EXYNOS5433_SERIAL_DRV_DATA,
},
{ },
};
MODULE_DEVICE_TABLE(platform, s3c24xx_serial_driver_ids);
#ifdef CONFIG_OF
static const struct of_device_id s3c24xx_uart_dt_match[] = {
{ .compatible = "samsung,s3c2410-uart",
.data = (void *)S3C2410_SERIAL_DRV_DATA },
{ .compatible = "samsung,s3c2412-uart",
.data = (void *)S3C2412_SERIAL_DRV_DATA },
{ .compatible = "samsung,s3c2440-uart",
.data = (void *)S3C2440_SERIAL_DRV_DATA },
{ .compatible = "samsung,s3c6400-uart",
.data = (void *)S3C6400_SERIAL_DRV_DATA },
{ .compatible = "samsung,s5pv210-uart",
.data = (void *)S5PV210_SERIAL_DRV_DATA },
{ .compatible = "samsung,exynos4210-uart",
.data = (void *)EXYNOS4210_SERIAL_DRV_DATA },
{ .compatible = "samsung,exynos5433-uart",
.data = (void *)EXYNOS5433_SERIAL_DRV_DATA },
{},
};
MODULE_DEVICE_TABLE(of, s3c24xx_uart_dt_match);
#endif
static struct platform_driver samsung_serial_driver = {
.probe = s3c24xx_serial_probe,
.remove = s3c24xx_serial_remove,
.id_table = s3c24xx_serial_driver_ids,
.driver = {
.name = "samsung-uart",
.pm = SERIAL_SAMSUNG_PM_OPS,
.of_match_table = of_match_ptr(s3c24xx_uart_dt_match),
},
};
module_platform_driver(samsung_serial_driver);
這裏我們看一下不同的soc都綁定了自己的硬件特有的信息，比如fifo大小等。
#ifdef CONFIG_CPU_S3C2410
static struct s3c24xx_serial_drv_data s3c2410_serial_drv_data = {
.info = &(struct s3c24xx_uart_info) {
.name = "Samsung S3C2410 UART",
.type = PORT_S3C2410,
.fifosize = 16,
.rx_fifomask = S3C2410_UFSTAT_RXMASK,
.rx_fifoshift = S3C2410_UFSTAT_RXSHIFT,
.rx_fifofull = S3C2410_UFSTAT_RXFULL,
.tx_fifofull = S3C2410_UFSTAT_TXFULL,
.tx_fifomask = S3C2410_UFSTAT_TXMASK,
.tx_fifoshift = S3C2410_UFSTAT_TXSHIFT,
.def_clk_sel = S3C2410_UCON_CLKSEL0,
.num_clks = 2,
.clksel_mask = S3C2410_UCON_CLKMASK,
.clksel_shift = S3C2410_UCON_CLKSHIFT,
},
.def_cfg = &(struct s3c2410_uartcfg) {
.ucon = S3C2410_UCON_DEFAULT,
.ufcon = S3C2410_UFCON_DEFAULT,
},
};
#define S3C2410_SERIAL_DRV_DATA ((kernel_ulong_t)&s3c2410_serial_drv_data)
#else
#define S3C2410_SERIAL_DRV_DATA (kernel_ulong_t)NULL
#endif
#ifdef CONFIG_CPU_S3C2412
static struct s3c24xx_serial_drv_data s3c2412_serial_drv_data = {
.info = &(struct s3c24xx_uart_info) {
.name = "Samsung S3C2412 UART",
.type = PORT_S3C2412,
.fifosize = 64,
.has_divslot = 1,
.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,
.def_clk_sel = S3C2410_UCON_CLKSEL2,
.num_clks = 4,
.clksel_mask = S3C2412_UCON_CLKMASK,
.clksel_shift = S3C2412_UCON_CLKSHIFT,
},
.def_cfg = &(struct s3c2410_uartcfg) {
.ucon = S3C2410_UCON_DEFAULT,
.ufcon = S3C2410_UFCON_DEFAULT,
},
};
#define S3C2412_SERIAL_DRV_DATA ((kernel_ulong_t)&s3c2412_serial_drv_data)
#else
#define S3C2412_SERIAL_DRV_DATA (kernel_ulong_t)NULL
#endif
#if defined(CONFIG_CPU_S3C2440) || defined(CONFIG_CPU_S3C2416) || \
defined(CONFIG_CPU_S3C2443) || defined(CONFIG_CPU_S3C2442)
static struct s3c24xx_serial_drv_data s3c2440_serial_drv_data = {
.info = &(struct s3c24xx_uart_info) {
.name = "Samsung S3C2440 UART",
.type = PORT_S3C2440,
.fifosize = 64,
.has_divslot = 1,
.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,
.def_clk_sel = S3C2410_UCON_CLKSEL2,
.num_clks = 4,
.clksel_mask = S3C2412_UCON_CLKMASK,
.clksel_shift = S3C2412_UCON_CLKSHIFT,
},
.def_cfg = &(struct s3c2410_uartcfg) {
.ucon = S3C2410_UCON_DEFAULT,
.ufcon = S3C2410_UFCON_DEFAULT,
},
};
#define S3C2440_SERIAL_DRV_DATA ((kernel_ulong_t)&s3c2440_serial_drv_data)
#else
#define S3C2440_SERIAL_DRV_DATA (kernel_ulong_t)NULL
#endif
#if defined(CONFIG_CPU_S3C6400) || defined(CONFIG_CPU_S3C6410)
static struct s3c24xx_serial_drv_data s3c6400_serial_drv_data = {
.info = &(struct s3c24xx_uart_info) {
.name = "Samsung S3C6400 UART",
.type = PORT_S3C6400,
.fifosize = 64,
.has_divslot = 1,
.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,
.def_clk_sel = S3C2410_UCON_CLKSEL2,
.num_clks = 4,
.clksel_mask = S3C6400_UCON_CLKMASK,
.clksel_shift = S3C6400_UCON_CLKSHIFT,
},
.def_cfg = &(struct s3c2410_uartcfg) {
.ucon = S3C2410_UCON_DEFAULT,
.ufcon = S3C2410_UFCON_DEFAULT,
},
};
#define S3C6400_SERIAL_DRV_DATA ((kernel_ulong_t)&s3c6400_serial_drv_data)
#else
#define S3C6400_SERIAL_DRV_DATA (kernel_ulong_t)NULL
#endif
#ifdef CONFIG_CPU_S5PV210
static struct s3c24xx_serial_drv_data s5pv210_serial_drv_data = {
.info = &(struct s3c24xx_uart_info) {
.name = "Samsung S5PV210 UART",
.type = PORT_S3C6400,
.has_divslot = 1,
.rx_fifomask = S5PV210_UFSTAT_RXMASK,
.rx_fifoshift = S5PV210_UFSTAT_RXSHIFT,
.rx_fifofull = S5PV210_UFSTAT_RXFULL,
.tx_fifofull = S5PV210_UFSTAT_TXFULL,
.tx_fifomask = S5PV210_UFSTAT_TXMASK,
.tx_fifoshift = S5PV210_UFSTAT_TXSHIFT,
.def_clk_sel = S3C2410_UCON_CLKSEL0,
.num_clks = 2,
.clksel_mask = S5PV210_UCON_CLKMASK,
.clksel_shift = S5PV210_UCON_CLKSHIFT,
},
.def_cfg = &(struct s3c2410_uartcfg) {
.ucon = S5PV210_UCON_DEFAULT,
.ufcon = S5PV210_UFCON_DEFAULT,
},
.fifosize = { 256, 64, 16, 16 },
};
#define S5PV210_SERIAL_DRV_DATA ((kernel_ulong_t)&s5pv210_serial_drv_data)
#else
#define S5PV210_SERIAL_DRV_DATA (kernel_ulong_t)NULL
#endif
#if defined(CONFIG_ARCH_EXYNOS)
#define EXYNOS_COMMON_SERIAL_DRV_DATA \
.info = &(struct s3c24xx_uart_info) { \
.name = "Samsung Exynos UART", \
.type = PORT_S3C6400, \
.has_divslot = 1, \
.rx_fifomask = S5PV210_UFSTAT_RXMASK, \
.rx_fifoshift = S5PV210_UFSTAT_RXSHIFT, \
.rx_fifofull = S5PV210_UFSTAT_RXFULL, \
.tx_fifofull = S5PV210_UFSTAT_TXFULL, \
.tx_fifomask = S5PV210_UFSTAT_TXMASK, \
.tx_fifoshift = S5PV210_UFSTAT_TXSHIFT, \
.def_clk_sel = S3C2410_UCON_CLKSEL0, \
.num_clks = 1, \
.clksel_mask = 0, \
.clksel_shift = 0, \
}, \
.def_cfg = &(struct s3c2410_uartcfg) { \
.ucon = S5PV210_UCON_DEFAULT, \
.ufcon = S5PV210_UFCON_DEFAULT, \
.has_fracval = 1, \
} \
static struct s3c24xx_serial_drv_data exynos4210_serial_drv_data = {
EXYNOS_COMMON_SERIAL_DRV_DATA,
.fifosize = { 256, 64, 16, 16 },
};
static struct s3c24xx_serial_drv_data exynos5433_serial_drv_data = {
EXYNOS_COMMON_SERIAL_DRV_DATA,
.fifosize = { 64, 256, 16, 256 },
};
#define EXYNOS4210_SERIAL_DRV_DATA ((kernel_ulong_t)&exynos4210_serial_drv_data)
#define EXYNOS5433_SERIAL_DRV_DATA ((kernel_ulong_t)&exynos5433_serial_drv_data)
#else
#define EXYNOS4210_SERIAL_DRV_DATA (kernel_ulong_t)NULL
#define EXYNOS5433_SERIAL_DRV_DATA (kernel_ulong_t)NULL
#endif
這裏我們分析的4.19內核，設備樹也是必須看的。
uart0: serial@e2900000 {
compatible = "samsung,s5pv210-uart";
reg = <0xe2900000 0x400>;
interrupt-parent = <&vic1>;
interrupts = <10>;
clock-names = "uart", "clk_uart_baud0",
"clk_uart_baud1";
clocks = <&clocks CLK_UART0>, <&clocks CLK_UART0>,
<&clocks SCLK_UART0>;
status = "disabled";
};
uart1: serial@e2900400 {
compatible = "samsung,s5pv210-uart";
reg = <0xe2900400 0x400>;
interrupt-parent = <&vic1>;
interrupts = <11>;
clock-names = "uart", "clk_uart_baud0",
"clk_uart_baud1";
clocks = <&clocks CLK_UART1>, <&clocks CLK_UART1>,
<&clocks SCLK_UART1>;
status = "disabled";
};
uart2: serial@e2900800 {
compatible = "samsung,s5pv210-uart";
reg = <0xe2900800 0x400>;
interrupt-parent = <&vic1>;
interrupts = <12>;
clock-names = "uart", "clk_uart_baud0",
"clk_uart_baud1";
clocks = <&clocks CLK_UART2>, <&clocks CLK_UART2>,
<&clocks SCLK_UART2>;
status = "disabled";
};
uart3: serial@e2900c00 {
compatible = "samsung,s5pv210-uart";
reg = <0xe2900c00 0x400>;
interrupt-parent = <&vic1>;
interrupts = <13>;
clock-names = "uart", "clk_uart_baud0",
"clk_uart_baud1";
clocks = <&clocks CLK_UART3>, <&clocks CLK_UART3>,
<&clocks SCLK_UART3>;
status = "disabled";
};
接下來這裏就直接看probe
static int s3c24xx_serial_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct s3c24xx_uart_port *ourport;
int index = probe_index;
int ret;
if (np) {
ret = of_alias_get_id(np, "serial");
if (ret >= 0)
index = ret;
}
dbg("s3c24xx_serial_probe(%p) %d\n", pdev, index);
if (index >= ARRAY_SIZE(s3c24xx_serial_ports)) {
dev_err(&pdev->dev, "serial%d out of range\n", index);
return -EINVAL;
}
ourport = &s3c24xx_serial_ports[index];
ourport->drv_data = s3c24xx_get_driver_data(pdev);
if (!ourport->drv_data) {
dev_err(&pdev->dev, "could not find driver data\n");
return -ENODEV;
}
ourport->baudclk = ERR_PTR(-EINVAL);
ourport->info = ourport->drv_data->info;
ourport->cfg = (dev_get_platdata(&pdev->dev)) ?
dev_get_platdata(&pdev->dev) :
ourport->drv_data->def_cfg;
if (np)
of_property_read_u32(np,
"samsung,uart-fifosize", &ourport->port.fifosize);
if (ourport->drv_data->fifosize[index])
ourport->port.fifosize = ourport->drv_data->fifosize[index];
else if (ourport->info->fifosize)
ourport->port.fifosize = ourport->info->fifosize;
/*
* DMA transfers must be aligned at least to cache line size,
* so find minimal transfer size suitable for DMA mode
*/
ourport->min_dma_size = max_t(int, ourport->port.fifosize,
dma_get_cache_alignment());
dbg("%s: initialising port %p...\n", __func__, ourport);
ret = s3c24xx_serial_init_port(ourport, pdev);
if (ret < 0)
return ret;
if (!s3c24xx_uart_drv.state) {
ret = uart_register_driver(&s3c24xx_uart_drv);
if (ret < 0) {
pr_err("Failed to register Samsung UART driver\n");
return ret;
}
}
dbg("%s: adding port\n", __func__);
uart_add_one_port(&s3c24xx_uart_drv, &ourport->port);
platform_set_drvdata(pdev, &ourport->port);
/*
* Deactivate the clock enabled in s3c24xx_serial_init_port here,
* so that a potential re-enablement through the pm-callback overlaps
* and keeps the clock enabled in this case.
*/
clk_disable_unprepare(ourport->clk);
ret = s3c24xx_serial_cpufreq_register(ourport);
if (ret < 0)
dev_err(&pdev->dev, "failed to add cpufreq notifier\n");
probe_index++;
return 0;
}
上面函數我們主要看三點。
1.序號，設備樹有定義別名，優先使用設備樹裏面的，如何沒有，則按註冊時序編號。
static int s3c24xx_serial_probe(struct platform_device *pdev)
{
int index = probe_index;
int ret;
if (np) {
ret = of_alias_get_id(np, "serial");
if (ret >= 0)
index = ret;
}
.....
probe_index++;
return 0;
}
設備樹定義別名我們之前有過，三星默認是沒定義的，定義的話也很簡單serial0 = &uart0; serial1 = &uart1; ......
aliases {
csis0 = &csis0;
fimc0 = &fimc0;
fimc1 = &fimc1;
fimc2 = &fimc2;
i2c0 = &i2c0;
i2c1 = &i2c1;
i2c2 = &i2c2;
i2s0 = &i2s0;
i2s1 = &i2s1;
i2s2 = &i2s2;
pinctrl0 = &pinctrl0;
spi0 = &spi0;
spi1 = &spi1;
};
2.接下來就是去除設端口，根據設備獲取對應的特有數據，初始化一些參數，進而進行硬件的初始化，中斷申請，寄存器映射等。
ourport = &s3c24xx_serial_ports[index];
ourport->drv_data = s3c24xx_get_driver_data(pdev);
if (!ourport->drv_data) {
dev_err(&pdev->dev, "could not find driver data\n");
return -ENODEV;
}
ourport->baudclk = ERR_PTR(-EINVAL);
ourport->info = ourport->drv_data->info;
ourport->cfg = (dev_get_platdata(&pdev->dev)) ?
dev_get_platdata(&pdev->dev) :
ourport->drv_data->def_cfg;
if (np)
of_property_read_u32(np,
"samsung,uart-fifosize", &ourport->port.fifosize);
if (ourport->drv_data->fifosize[index])
ourport->port.fifosize = ourport->drv_data->fifosize[index];
else if (ourport->info->fifosize)
ourport->port.fifosize = ourport->info->fifosize;
/*
* DMA transfers must be aligned at least to cache line size,
* so find minimal transfer size suitable for DMA mode
*/
ourport->min_dma_size = max_t(int, ourport->port.fifosize,
dma_get_cache_alignment());
dbg("%s: initialising port %p...\n", __func__, ourport);
ret = s3c24xx_serial_init_port(ourport, pdev);
if (ret < 0)
return ret;
if (!s3c24xx_uart_drv.state) {
ret = uart_register_driver(&s3c24xx_uart_drv);
if (ret < 0) {
pr_err("Failed to register Samsung UART driver\n");
return ret;
}
}
當然這裏我們就看一下資源串口初始化和資源申請，寄存器映射，當然中斷這裏申請了，在別的地方初始化的。
/* 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 platform_device *platdev)
{
struct uart_port *port = &ourport->port;
struct s3c2410_uartcfg *cfg = ourport->cfg;
struct resource *res;
int ret;
dbg("s3c24xx_serial_init_port: port=%p, platdev=%p\n", port, platdev);
if (platdev == NULL)
return -ENODEV;
if (port->mapbase != 0)
return -EINVAL;
/* setup info for port */
port->dev = &platdev->dev;
/* Startup sequence is different for s3c64xx and higher SoC's */
if (s3c24xx_serial_has_interrupt_mask(port))
s3c24xx_serial_ops.startup = s3c64xx_serial_startup;
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);
if (res == NULL) {
dev_err(port->dev, "failed to find memory resource for uart\n");
return -EINVAL;
}
dbg("resource %pR)\n", res);
port->membase = devm_ioremap(port->dev, res->start, resource_size(res));
if (!port->membase) {
dev_err(port->dev, "failed to remap controller address\n");
return -EBUSY;
}
port->mapbase = res->start;
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;
/*
* DMA is currently supported only on DT platforms, if DMA properties
* are specified.
*/
if (platdev->dev.of_node && of_find_property(platdev->dev.of_node,
"dmas", NULL)) {
ourport->dma = devm_kzalloc(port->dev,
sizeof(*ourport->dma),
GFP_KERNEL);
if (!ourport->dma) {
ret = -ENOMEM;
goto err;
}
}
ourport->clk = clk_get(&platdev->dev, "uart");
if (IS_ERR(ourport->clk)) {
pr_err("%s: Controller clock not found\n",
dev_name(&platdev->dev));
ret = PTR_ERR(ourport->clk);
goto err;
}
ret = clk_prepare_enable(ourport->clk);
if (ret) {
pr_err("uart: clock failed to prepare+enable: %d\n", ret);
clk_put(ourport->clk);
goto err;
}
/* Keep all interrupts masked and cleared */
if (s3c24xx_serial_has_interrupt_mask(port)) {
wr_regl(port, S3C64XX_UINTM, 0xf);
wr_regl(port, S3C64XX_UINTP, 0xf);
wr_regl(port, S3C64XX_UINTSP, 0xf);
}
dbg("port: map=%pa, mem=%p, irq=%d (%d,%d), clock=%u\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;
err:
port->mapbase = 0;
return ret;
}
這裏我們看一下串口的中斷申請在那個函數裏。
static struct uart_ops s3c24xx_serial_ops = {
.pm = s3c24xx_serial_pm,
.tx_empty = s3c24xx_serial_tx_empty,
.get_mctrl = s3c24xx_serial_get_mctrl,
.set_mctrl = s3c24xx_serial_set_mctrl,
.stop_tx = s3c24xx_serial_stop_tx,
.start_tx = s3c24xx_serial_start_tx,
.stop_rx = s3c24xx_serial_stop_rx,
.break_ctl = s3c24xx_serial_break_ctl,
.startup = s3c24xx_serial_startup,
.shutdown = s3c24xx_serial_shutdown,
.set_termios = s3c24xx_serial_set_termios,
.type = s3c24xx_serial_type,
.release_port = s3c24xx_serial_release_port,
.request_port = s3c24xx_serial_request_port,
.config_port = s3c24xx_serial_config_port,
.verify_port = s3c24xx_serial_verify_port,
#if defined(CONFIG_SERIAL_SAMSUNG_CONSOLE) && defined(CONFIG_CONSOLE_POLL)
.poll_get_char = s3c24xx_serial_get_poll_char,
.poll_put_char = s3c24xx_serial_put_poll_char,
#endif
};
static int s3c24xx_serial_startup(struct uart_port *port)
{
struct s3c24xx_uart_port *ourport = to_ourport(port);
int ret;
dbg("s3c24xx_serial_startup: port=%p (%08llx,%p)\n",
port, (unsigned long long)port->mapbase, port->membase);
rx_enabled(port) = 1;
ret = request_irq(ourport->rx_irq, s3c24xx_serial_rx_chars, 0,
s3c24xx_serial_portname(port), ourport);
if (ret != 0) {
dev_err(port->dev, "cannot get irq %d\n", ourport->rx_irq);
return ret;
}
ourport->rx_claimed = 1;
dbg("requesting tx irq...\n");
tx_enabled(port) = 1;
ret = request_irq(ourport->tx_irq, s3c24xx_serial_tx_chars, 0,
s3c24xx_serial_portname(port), ourport);
if (ret) {
dev_err(port->dev, "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 */
return ret;
err:
s3c24xx_serial_shutdown(port);
return ret;
}
上面我們已經看到了發生和中斷接收函數了，具體的細節就不再描述。