SPI子系统

一、SPI子系统模型





三个组成部分：

SPI核心：连通了SPI客户驱动、SPI主控制器驱动

SPI控制器驱动：驱动芯片中的SPI控制器

SPI的FLASH（客户驱动）



二、SPI控制器驱动分析

1. static int __init s3c24xx_spi_probe(struct platform_device *pdev)
2. {
3. struct s3c2410_spi_info *pdata;
4. struct s3c24xx_spi *hw;
5. struct spi_master *master;
6. struct resource *res;
7. int err = 0;
8. master = spi_alloc_master(&pdev->dev, sizeof(struct s3c24xx_spi));
9. if (master == NULL) {
10. dev_err(&pdev->dev, "No memory for spi_master\n");
11. err = -ENOMEM;
12. goto err_nomem;
13. }
14. hw = spi_master_get_devdata(master);
15. memset(hw, 0, sizeof(struct s3c24xx_spi));
16. hw->master = spi_master_get(master);
17. hw->pdata = pdata = pdev->dev.platform_data;
18. hw->dev = &pdev->dev;
19. if (pdata == NULL) {
20. dev_err(&pdev->dev, "No platform data supplied\n");
21. err = -ENOENT;
22. goto err_no_pdata;
23. }
24. platform_set_drvdata(pdev, hw);
25. init_completion(&hw->done);
26. /* setup the master state. */
27. master->num_chipselect = hw->pdata->num_cs;
28. master->bus_num = pdata->bus_num;
29. /* setup the state for the bitbang driver */
30. hw->bitbang.master = hw->master;
31. hw->bitbang.setup_transfer = s3c24xx_spi_setupxfer;
32. hw->bitbang.chipselect = s3c24xx_spi_chipsel;
33. hw->bitbang.txrx_bufs = s3c24xx_spi_txrx;
34. hw->bitbang.master->setup = s3c24xx_spi_setup;
35. dev_dbg(hw->dev, "bitbang at %p\n", &hw->bitbang);
36. /* find and map our resources */
37. res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
38. if (res == NULL) {
39. dev_err(&pdev->dev, "Cannot get IORESOURCE_MEM\n");
40. err = -ENOENT;
41. goto err_no_iores;
42. }
43. hw->ioarea = request_mem_region(res->start, (res->end - res->start)+1,
44. pdev->name);                                                                    //设置硬件资源
45. if (hw->ioarea == NULL) {
46. dev_err(&pdev->dev, "Cannot reserve region\n");
47. err = -ENXIO;
48. goto err_no_iores;
49. }
50. hw->regs = ioremap(res->start, (res->end - res->start)+1);                                      //获取映射地址
51. if (hw->regs == NULL) {
52. dev_err(&pdev->dev, "Cannot map IO\n");
53. err = -ENXIO;
54. goto err_no_iomap;
55. }
56. hw->irq = platform_get_irq(pdev, 0);                                                            //获取中断号
57. if (hw->irq < 0) {
58. dev_err(&pdev->dev, "No IRQ specified\n");
59. err = -ENOENT;
60. goto err_no_irq;
61. }
62. err = request_irq(hw->irq, s3c24xx_spi_irq, 0, pdev->name, hw);                                 //注册中断
63. if (err) {
64. dev_err(&pdev->dev, "Cannot claim IRQ\n");
65. goto err_no_irq;
66. }
67. hw->clk = clk_get(&pdev->dev, "spi");
68. if (IS_ERR(hw->clk)) {
69. dev_err(&pdev->dev, "No clock for device\n");
70. err = PTR_ERR(hw->clk);
71. goto err_no_clk;
72. }
73. /* setup any gpio we can */
74. if (!pdata->set_cs) {
75. if (pdata->pin_cs < 0) {
76. dev_err(&pdev->dev, "No chipselect pin\n");
77. goto err_register;
78. }
79. err = gpio_request(pdata->pin_cs, dev_name(&pdev->dev));
80. if (err) {
81. dev_err(&pdev->dev, "Failed to get gpio for cs\n");
82. goto err_register;
83. }
84. hw->set_cs = s3c24xx_spi_gpiocs;
85. gpio_direction_output(pdata->pin_cs, 1);
86. } else
87. hw->set_cs = pdata->set_cs;
88. s3c24xx_spi_initialsetup(hw);                                                                    //初始化部分
89. /* register our spi controller */
90. err = spi_bitbang_start(&hw->bitbang);                                                           //完成注册
91. if (err) {
92. dev_err(&pdev->dev, "Failed to register SPI master\n");
93. goto err_register;
94. }
95. return 0;
96. err_register:
97. if (hw->set_cs == s3c24xx_spi_gpiocs)
98. gpio_free(pdata->pin_cs);
99. clk_disable(hw->clk);
100. clk_put(hw->clk);
101. err_no_clk:
102. free_irq(hw->irq, hw);
103. err_no_irq:
104. iounmap(hw->regs);
105. err_no_iomap:
106. release_resource(hw->ioarea);
107. kfree(hw->ioarea);
108. err_no_iores:
109. err_no_pdata:
110. spi_master_put(hw->master);;
111. err_nomem:
112. return err;
113. }

s3c24xx_spi_initialsetup:

1. static void s3c24xx_spi_initialsetup(struct s3c24xx_spi *hw)
2. {
3. /* for the moment, permanently enable the clock */
4. clk_enable(hw->clk);
5. /* program defaults into the registers */
6. writeb(0xff, hw->regs + S3C2410_SPPRE);
7. writeb(SPPIN_DEFAULT, hw->regs + S3C2410_SPPIN);
8. writeb(SPCON_DEFAULT, hw->regs + S3C2410_SPCON);                                       //设置成中断触发方式
9. if (hw->pdata) {
10. if (hw->set_cs == s3c24xx_spi_gpiocs)
11. gpio_direction_output(hw->pdata->pin_cs, 1);
12. if (hw->pdata->gpio_setup)
13. hw->pdata->gpio_setup(hw->pdata, 1);
14. }
15. }

中断函数s3c24xx_spi_irq:

1. static irqreturn_t s3c24xx_spi_irq(int irq, void *dev)
2. {
3. struct s3c24xx_spi *hw = dev;
4. unsigned int spsta = readb(hw->regs + S3C2410_SPSTA);
5. unsigned int count = hw->count;
6. if (spsta & S3C2410_SPSTA_DCOL) {
7. dev_dbg(hw->dev, "data-collision\n");
8. complete(&hw->done);
9. goto irq_done;
10. }
11. if (!(spsta & S3C2410_SPSTA_READY)) {
12. dev_dbg(hw->dev, "spi not ready for tx?\n");
13. complete(&hw->done);
14. goto irq_done;
15. }
16. hw->count++;
17. if (hw->rx)
18. hw->rx[count] = readb(hw->regs + S3C2410_SPRDAT);
19. count++;
20. if (count < hw->len)                                                                            //判断长度来收发？
21. writeb(hw_txbyte(hw, count), hw->regs + S3C2410_SPTDAT);
22. else
23. complete(&hw->done);
24. irq_done:
25. return IRQ_HANDLED;
26. }