imx6配置EIM总线，用于16C554拓展串口使用

杨帆！起航！ · 发表于 2015-12-24 15:57:32

本帖最后由杨帆！起航！于 2016-9-23 10:58 编辑

拓展16C554时，用到CS0片选，首先用需要配置EIM总线
/* These registers settings are just valid for Numonyx M29W256GL7AN6E. */
static void mx6q_setup_weimcs(void)
{
      void __iomem *nor_reg = MX6_IO_ADDRESS(WEIM_BASE_ADDR);
      void __iomem *ccm_reg = MX6_IO_ADDRESS(CCM_BASE_ADDR);
      unsigned int reg;
      struct clk *clk;
      u32 rate;

      /* CLKCTL_CCGR6: Set emi_slow_clock to be on in all modes */
      reg = readl(ccm_reg + 0x80);
      reg |= 0x00000C00;
      writel(reg, ccm_reg + 0x80);

      /* Timing settings below based upon datasheet for M29W256GL7AN6E
         These setting assume that the EIM_SLOW_CLOCK is set to 132 MHz */
      clk = clk_get(NULL, "emi_slow_clk");
      if (IS_ERR(clk))
            printk(KERN_ERR "emi_slow_clk not found\n");

      rate = clk_get_rate(clk);
      if (rate != 132000000)
            printk(KERN_ERR "Warning: emi_slow_clk not set to 132 MHz!"
                     " WEIM NOR timing may be incorrect!\n");

      /*
      * For EIM General Configuration registers.
      *
      * CS0GCR1:
      *       GBC = 0; CSREC = 6; DSZ = 2; BL = 0;
      *       CREP = 1; CSEN = 1;
      *
      *       EIM Operation Mode: MUM = SRD = SWR = 0.
      *             (Async write/Async page read, none multiplexed)
      *
      * CS0GCR2:
      *       ADH = 1
      */
      writel(0x00620081, nor_reg);
      writel(0x00000001, nor_reg + 0x00000004);

      /*
      * For EIM Read Configuration registers.
      *
      * CS0RCR1:
      *       RWSC = 1C;
      *       RADVA = 0; RADVN = 2;
      *       OEA = 2; OEN = 0;
      *       RCSA = 0; RCSN = 0
      *
      * CS0RCR2:
      *       APR = 1 (Async Page Read);
      *       PAT = 4 (6 EIM clock sycles)
      */
      writel(0x1C022000, nor_reg + 0x00000008);
      writel(0x0000C000, nor_reg + 0x0000000C);

      /*
      * For EIM Write Configuration registers.
      *
      * CS0WCR1:
      *       WWSC = 20;
      *       WADVA = 0; WADVN = 1;
      *       WBEA = 1; WBEN = 2;
      *       WEA = 1; WEN = 6;
      *       WCSA = 1; WCSN = 2;
      *
      * CS0WCR2:
      *       WBCDD = 0
      */
      writel(0x1404a38e, nor_reg + 0x00000010);
      writel(0x00000000, nor_reg + 0x00000014);
}
6个寄存器的配置
3364    writel(0x00660081, nor_reg + 0x00000000); 片选0  128M 映射空间数据线16-23 8位的
3365    writel(0x00000001, nor_reg + 0x00000004);
3366    writel(0x1c022000, nor_reg + 0x00000008);
3367    writel(0x0000C000, nor_reg + 0x0000000c);
3368    writel(0x1404a38e, nor_reg + 0x00000010);
3369    writel(0x00000000, nor_reg + 0x00000014);
3370    writel(0x00000001, nor_reg + 0x90);
3371    printk("GPR1__CSx____is____end%x\n",reg);

增加拓展串口功能
kernel_imx/drivers/tty/serial/8250_exar_st16c554.c
16 #define PORT(_base,_irq)             \
17    {                      \
18       .iobase    = _base,       \
19       .irq       = _irq,       \
20       .uartclk = 11059200,    \
21       .iotype    = UPIO_PORT,       \
22       .flags    = UPF_BOOT_AUTOCONF, \
23    }
24 #define CS0_BASE 0x08000000 //add cjf-_-
25
26 #define CARD1_BASE  CS0_BASE + 0x10
27 #define CARD2_BASE  CS0_BASE + 0x20
28 #define CARD3_BASE  CS0_BASE + 0x30
29 #define CARD4_BASE  CS0_BASE + 0x40
30
31 #define 16C554_INTA gpio_to_irq(IMX_GPIO_NR(1,10))
32 #define 16C554_INTB gpio_to_irq(IMX_GPIO_NR(1,15))
33 #define 16C554_INTC gpio_to_irq(IMX_GPIO_NR(1,14))
34 #define 16C554_INTD gpio_to_irq(IMX_GPIO_NR(1,11))
35
36 static struct plat_serial8250_port exar_data[] = {
37    PORT(CARD1_BASE, 16C554_INTA),
38    PORT(CARD2_BASE, 16C554_INTB),
39    PORT(CARD3_BASE, 16C554_INTC),
40    PORT(CARD4_BASE, 16C554_INTD),
41    { },
42 };
需要注意的地方：
membase：该成员描述的该串口接口寄存器虚拟地址的基地址。在初始化该成员时，需要自己把该串口接口寄存器的物理地址映射到虚拟地址空间。并且该映射工作需要在内核的板级初始化阶段完成。
.mapbase指的是16C554的物理基地址，注意不是membase；
.uartclk是16C554晶振的频率，其最高波特率为.uartclk/16；
.iotype指的是访问类型，与硬件的连接相关,
            UPIO_PORT 端口地址,8位
      UPIO_HUB6
      UPIO_MEM 8位的内存地址
      UPIO_MEM32 32位的内存地址
            UPIO_MEM32表示为32位总线访问方式，即访问16C554的寄存器时，读取32位数，取低8位；
.regshift也跟硬件的物理连接相关，指的是访问16C554的每个地址时的偏移，也就是16C554的A0对应CPU的A几；
UPF_IOREMAP指16C554寄存器需要映射到虚拟地址访问；

8250.c 实行工作流程

serial8250_register_ports
      serial8250_isa_init_ports
platform_driver_register
      serial8250_isa_driver
            serial8250_probe 4次循环{
                     serial8250_register_port
                              uart_add_one_port -> (文件serial_core.c) uart_configure_port->uart_report_port(打印串口信息)
                                    uart_ops serial8250_pops
                                             serial8250_config_port
                                                      autoconfig
                                                            autoconfig_16550a
                                             autoconfig_16550a
                                                      uart_config



}

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