S3C2440驱动简析——串口驱动

对于驱动的学习停歇了几乎一周的时间，期间忙于补习Linux应用编程和搜索驱动、内核相关书籍，以便之后更进一步地学习。在之前友善提供的驱动例程里面，涉及的知识面非常有限，需要研究更多的驱动源码，了解更多的驱动知识，是当务之急。研究别人代码的同时，当然不忘自己也要动手练习。以下贴出串口驱动程序，并在程序里附上简要注释。

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1. // linux/drivers/serial/s3c2440.c
2. *
3. *DriverforSamsungS3C2440andS3C2442SoConboardUARTs.
4. *
5. *BenDooks,Copyright(c)2003-2005,2008SimtecElectronics
6. *http://armlinux.simtec.co.uk/
7. *
8. *Thisprogramisfreesoftware;youcanredistributeitand/ormodify
9. *itunderthetermsoftheGNUGeneralPublicLicenseversion2as
10. *publishedbytheFreeSoftwareFoundation.
11. //
13. #include"linux/module.h"
14. #include"linux/ioport.h"
15. #include"linux/io.h"
16. #include"linux/platform_device.h"
17. #include"linux/init.h"
18. #include"linux/serial_core.h"
19. #include"linux/serial.h"
21. #include"asm/irq.h"
22. #include"mach/hardware.h"
24. #include"plat/regs-serial.h"
25. #include"mach/regs-gpio.h"
27. #include"samsung.h"
30. staticints3c2440_serial_setsource(structuart_port*port,
31. structs3c24xx_uart_clksrc*clk)
32. {//本函数选定串口端口和时钟源
33. unsignedlongucon=rd_regl(port,S3C2410_UCON);//读取寄存器UCON
35. // todo-properfclk<>nonfclkswitch.//
37. ucon&=~S3C2440_UCON_CLKMASK;//#defineS3C2440_UCON_CLKMASK(3<10)
39. if(strcmp(clk->name,"uclk")==0)//选择时钟源
40. ucon|=S3C2440_UCON_UCLK;
41. elseif(strcmp(clk->name,"pclk")==0)
42. ucon|=S3C2440_UCON_PCLK;
43. elseif(strcmp(clk->name,"fclk")==0)
44. ucon|=S3C2440_UCON_FCLK;
45. else{
46. printk(KERN_ERR"unknownclocksource%s/n",clk->name);
47. return-EINVAL;
48. }
50. wr_regl(port,S3C2410_UCON,ucon);//把设置过的ucon写回串口控制寄存器
51. return0;
52. }
55. staticints3c2440_serial_getsource(structuart_port*port,
56. structs3c24xx_uart_clksrc*clk)
57. {//设置时钟源和对应预分频值
58. unsignedlongucon=rd_regl(port,S3C2410_UCON);
59. unsignedlongucon0,ucon1,ucon2;
61. switch(ucon&S3C2440_UCON_CLKMASK){
62. caseS3C2440_UCON_UCLK:
63. clk->divisor=1;
64. clk->name="uclk";
65. break;
67. caseS3C2440_UCON_PCLK:
68. caseS3C2440_UCON_PCLK2:
69. clk->divisor=1;
70. clk->name="pclk";
71. break;
73. caseS3C2440_UCON_FCLK:
74. //thefunofcalculatingtheuartdivisorson
75. *thes3c2440//
77. ucon0=__raw_readl(S3C24XX_VA_UART0+S3C2410_UCON);
78. ucon1=__raw_readl(S3C24XX_VA_UART1+S3C2410_UCON);
79. ucon2=__raw_readl(S3C24XX_VA_UART2+S3C2410_UCON);
81. printk("ucons:lx,lx,lx/n",ucon0,ucon1,ucon2);
83. ucon0&=S3C2440_UCON0_divMASK;
84. ucon1&=S3C2440_UCON1_divMASK;
85. ucon2&=S3C2440_UCON2_divMASK;
87. if(ucon0!=0){
88. clk->divisor=ucon0>>S3C2440_UCON_divSHIFT;
89. clk->divisor+=6;
90. }elseif(ucon1!=0){
91. clk->divisor=ucon1>>S3C2440_UCON_divSHIFT;
92. clk->divisor+=21;
93. }elseif(ucon2!=0){
94. clk->divisor=ucon2>>S3C2440_UCON_divSHIFT;
95. clk->divisor+=36;
96. }else{
97. //manualcalims44,seemstobe9//
98. clk->divisor=9;
99. }
101. clk->name="fclk";
102. break;
103. }
105. return0;
106. }
108. staticints3c2440_serial_resetport(structuart_port*port,
109. structs3c2410_uartcfg*cfg)
110. {//重设串口
111. unsignedlongucon=rd_regl(port,S3C2410_UCON);
113. dbg("s3c2440_serial_resetport:port=%p(lx),cfg=%p/n",
114. port,port->mapbase,cfg);
116. //ensurewedontchangetheclocksettings...//
118. ucon&=(S3C2440_UCON0_divMASK|(3<10));
120. wr_regl(port,S3C2410_UCON,ucon|cfg->ucon);//重新设置寄存器UCON
121. wr_regl(port,S3C2410_ULCON,cfg->ulcon);//重新设置寄存器ULCON
123. //resetbothfifos//
125. wr_regl(port,S3C2410_UFCON,cfg->ufcon|S3C2410_UFCON_RESETBOTH);//重启fifo
126. wr_regl(port,S3C2410_UFCON,cfg->ufcon);//重新设定寄存器UFCON
128. return0;
129. }
131. staticstructs3c24xx_uart_infos3c2440_uart_inf={//串口设备环境信息和提供的操作函数
132. .name="SamsungS3C2440UART",
133. .type=PORT_S3C2440,
134. .fifosize=64,
135. .rx_fifomask=S3C2440_UFSTAT_RXMASK,
136. .rx_fifoshift=S3C2440_UFSTAT_RXSHIFT,
137. .rx_fifofull=S3C2440_UFSTAT_RXFULL,
138. .tx_fifofull=S3C2440_UFSTAT_TXFULL,
139. .tx_fifomask=S3C2440_UFSTAT_TXMASK,
140. .tx_fifoshift=S3C2440_UFSTAT_TXSHIFT,
141. .get_clksrc=s3c2440_serial_getsource,
142. .set_clksrc=s3c2440_serial_setsource,
143. .reset_port=s3c2440_serial_resetport,