2021年10月29日 | Linux之ARM（IMX6U）裸机模仿STM32驱动开发格式

模仿 STM32 驱动开发格式实验

C 语言编写 LED 灯驱动的时候，每个寄存器的地址我们都需要写宏定义，使用起来非常的不方便。我们在学习 STM32 的时候，可以使用“GPIOB->ODR”这种方式来给GPIOB 的寄存器 ODR 赋值，因为在 STM32 中同属于一个外设的所有寄存器地址基本是相邻的(有些会有保留寄存器)。因此我们可以借助 C 语言里面的结构体成员地址递增的特点来将某个外设的所有寄存器写入到一个结构体里面，然后定义一个结构体指针指向这个外设的寄存器基地址，这样我们就可以通过这个结构体指针来访问这个外设的所有寄存器。同理， I.MX6U 也可以使用这种方法来定义外设寄存器，本次我们就模仿 STM32 里面的寄存器定义方式来编写I.MX6U 的驱动

1.模仿STM32寄存器的定义

1.1、STM32寄存器定义简介

为了开发方便， ST 官方为 STM32F103 编写了一个叫做 stm32f10x.h 的文件，在这个文件里面定义了 STM32F103 所有外设寄存器，我们可以使用其定义的寄存器来进行开发，比如我们可以用如下代码来初始化一个 GPIO：

GPIOE->CRL&=0XFF0FFFFF;

GPIOE->CRL|=0X00300000; //PE5 推挽输出

GPIOE->ODR|=1<<5; //PE5 输出高

上述代码是初始化 STM32 的 PE5 这个 GPIO 为推挽输出，需要配置的就是 GPIOE 的寄存器 CRL 和 ODR， “GPIOE”的定义：

#define GPIOE ((GPIO_TypeDef *) GPIOE_BASE)

可以看出“GPIOE”是个宏定义，是一个指向地址 GPIOE_BASE 的结构体指针，结构体为GPIO_TypeDef， GPIO_TypeDef 和 GPIOE_BASE 的定义如下：

typedef struct

{

__IO uint32_t CRL;

__IO uint32_t CRH;

__IO uint32_t IDR;

__IO uint32_t ODR;

__IO uint32_t BSRR;

__IO uint32_t BRR;

__IO uint32_t LCKR;

} GPIO_TypeDef;

#define GPIOE_BASE (APB2PERIPH_BASE + 0x1800)

#define APB2PERIPH_BASE (PERIPH_BASE + 0x10000)

#define PERIPH_BASE ((uint32_t)0x40000000)

上述定义中 GPIO_TypeDef 是个结构体，结构体里面的成员变量有 CRL、 CRH、 IDR、 ODR、BSRR、 BRR 和 LCKR，这些都是 GPIO 的寄存器，每个成员变量都是 32 位(4 字节)，这些寄存器在结构体中的位置都是按照其地址值从小到大排序的。GPIOE_BASE 就是 GPIOE 的基地址，其为:

GPIOE_BASE=APB2PERIPH_BASE+0x1800

  = PERIPH_BASE + 0x10000 + 0x1800

  =0x40000000 + 0x10000 + 0x1800

  =0x40011800

GPIOE_BASE 的基地址为 0x40011800，宏 GPIOE 指向这个地址，因此 GPIOE 的寄存器CRL 的地址就是 0X40011800，寄存器 CRH 的地址就是 0X40011800+4=0X40011804，其他寄存器地址以此类推。我们要操作 GPIOE 的 ODR 寄存器的话就可以通过“GPIOE->ODR”来实现，这个方法是借助了结构体成员地址连续递增的原理。

了解了 STM32 的寄存器定义以后，我们就可以参考其原理来编写 I.MX6U 的外设寄存器定义了。 NXP 官方并没有为 I.MX6UL 编写类似 stm32f10x.h 这样的文件， NXP 只为 I.MX6ULL提供了类似 stm32f10x.h 这样的文件，名为 MCIMX6Y2.h，但是 I.MX6UL 和 I.MX6ULL 几乎一模一样，所以文件 MCIMX6Y2.h 可以用在 I.MX6UL 上。

1.2、I.MX6U寄存器定义

参考 STM32 的官方文件来编写 I.MX6U 的寄存器定义，比如 IO 复用寄存器组“IOMUX_SW_MUX_CTL_PAD_XX”，步骤如下：

1.编写外设结构体

/*

* IOMUX 寄存器组

*/

 typedef struct

 {

  volatile unsigned int BOOT_MODE0;

volatile unsigned int BOOT_MODE1;

volatile unsigned int SNVS_TAMPER0;

volatile unsigned int SNVS_TAMPER1;

………

  volatile unsigned int CSI_DATA00;

volatile unsigned int CSI_DATA01;

  volatile unsigned int CSI_DATA02;

volatile unsigned int CSI_DATA03;

volatile unsigned int CSI_DATA04;

  volatile unsigned int CSI_DATA05;

volatile unsigned int CSI_DATA06;

volatile unsigned int CSI_DATA07;

/* 为了缩短代码，其余 IO 复用寄存器省略 */

115}IOMUX_SW_MUX_Tpye;

上述结构体 IOMUX_SW_MUX_Type 就是 IO 复用寄存器组，成员变量是每个 IO 对应的复用寄存器，每个寄存器的地址是 32 位，每个成员都使用“volatile”进行了修饰，目的是防止编译器优化。

2.定义 IO 复用寄存器组的基地址

根据结构体 IOMUX_SW_MUX_Type 的定义，其第一个成员变量为 BOOT_MODE0，也就是 BOOT_MODE0 这个 IO 的 IO 复用寄存器，查找 I.MX6U 的参考手册可以得知其地址为0X020E0014，所以 IO 复用寄存器组的基地址就是 0X020E0014，定义如下:

#define IOMUX_SW_MUX_BASE (0X020E0014)

3.定义访问指针

访问指针定义如下：

#define IOMUX_SW_MUX ((IOMUX_SW_MUX_Type *)IOMUX_SW_MUX_BASE)

通过上面三步我们就可以通过“IOMUX_SW_MUX->GPIO1_IO03”来访问 GPIO1_IO03 的IO 复用寄存器了。同样的，其他的外设寄存器都可以通过这三步来定义

2.硬件原理分析，和之前的硬件资源一样

3.实验程序编写

创建 VSCode 工程，工作区名字为“ledc_stm32”，新建三个文件： start.s、 main.c 和 imx6ul.h。

其中 start.s 是汇编文件， main.c和 imx6ul.h 是 C 文件，

1. imx6ul.h

文件 imx6ul.h 用来存放外设寄存器定义，在 imx6ul.h 中输入如下代码：

/* 

 * 外设寄存器组的基地址 

 */

#define CCM_BASE (0X020C4000)

#define CCM_ANALOG_BASE (0X020C8000)

#define IOMUX_SW_MUX_BASE (0X020E0014)

#define IOMUX_SW_PAD_BASE (0X020E0204)

#define GPIO1_BASE                  (0x0209C000)

#define GPIO2_BASE                  (0x020A0000)

#define GPIO3_BASE                  (0x020A4000)

#define GPIO4_BASE                  (0x020A8000)

#define GPIO5_BASE                  (0x020AC000)

/* 

 * CCM寄存器结构体定义，分为CCM和CCM_ANALOG 

 */

typedef struct 

{

volatile unsigned int CCR;

volatile unsigned int CCDR;

volatile unsigned int CSR;

volatile unsigned int CCSR;

volatile unsigned int CACRR;

volatile unsigned int CBCDR;

volatile unsigned int CBCMR;

volatile unsigned int CSCMR1;

volatile unsigned int CSCMR2;

volatile unsigned int CSCDR1;

volatile unsigned int CS1CDR;

volatile unsigned int CS2CDR;

volatile unsigned int CDCDR;

volatile unsigned int CHSCCDR;

volatile unsigned int CSCDR2;

volatile unsigned int CSCDR3;

volatile unsigned int RESERVED_1[2];

volatile unsigned int CDHIPR;  

volatile unsigned int RESERVED_2[2];

volatile unsigned int CLPCR;

volatile unsigned int CISR;

volatile unsigned int CIMR;

volatile unsigned int CCOSR;

volatile unsigned int CGPR;

volatile unsigned int CCGR0;

volatile unsigned int CCGR1;

volatile unsigned int CCGR2;

volatile unsigned int CCGR3;

volatile unsigned int CCGR4;

volatile unsigned int CCGR5;

volatile unsigned int CCGR6;

volatile unsigned int RESERVED_3[1];

volatile unsigned int CMEOR;

} CCM_Type; 

typedef struct 

{

volatile unsigned int PLL_ARM;

volatile unsigned int PLL_ARM_SET;

volatile unsigned int PLL_ARM_CLR;

volatile unsigned int PLL_ARM_TOG;

volatile unsigned int PLL_USB1;

volatile unsigned int PLL_USB1_SET;

volatile unsigned int PLL_USB1_CLR;

volatile unsigned int PLL_USB1_TOG;

volatile unsigned int PLL_USB2;

volatile unsigned int PLL_USB2_SET;

volatile unsigned int PLL_USB2_CLR;

volatile unsigned int PLL_USB2_TOG;

volatile unsigned int PLL_SYS;

volatile unsigned int PLL_SYS_SET;

volatile unsigned int PLL_SYS_CLR;

volatile unsigned int PLL_SYS_TOG;

volatile unsigned int PLL_SYS_SS;

volatile unsigned int RESERVED_1[3];

volatile unsigned int PLL_SYS_NUM;

volatile unsigned int RESERVED_2[3];

volatile unsigned int PLL_SYS_DENOM; 

volatile unsigned int RESERVED_3[3];

volatile unsigned int PLL_AUDIO;

volatile unsigned int PLL_AUDIO_SET;

volatile unsigned int PLL_AUDIO_CLR;

volatile unsigned int PLL_AUDIO_TOG;

volatile unsigned int PLL_AUDIO_DENOM;

volatile unsigned int RESERVED_4[3];

volatile unsigned int PLL_VIDEO;

volatile unsigned int PLL_VIDEO_SET;

volatile unsigned int PLL_VIDEO_CLR;

volatile unsigned int PLL_VIDEO_TOG;

volatile unsigned int PLL_VIDEO_NUM;

volatile unsigned int RESERVED_5[3];

volatile unsigned int PLL_VIDEO_DENOM;

volatile unsigned int RESERVED_6[7];

volatile unsigned int PLL_ENET;

volatile unsigned int PLL_ENET_SET;

volatile unsigned int PLL_ENET_CLR;

volatile unsigned int PLL_ENET_TOG;

volatile unsigned int PFD_480;

volatile unsigned int PFD_480_SET;

volatile unsigned int PFD_480_CLR;

volatile unsigned int PFD_480_TOG;

volatile unsigned int PFD_528;

volatile unsigned int PFD_528_SET;

volatile unsigned int PFD_528_CLR;

volatile unsigned int PFD_528_TOG;

volatile unsigned int RESERVED_7[16];

volatile unsigned int MISC0;

volatile unsigned int MISC0_SET;

volatile unsigned int MISC0_CLR;

volatile unsigned int MISC0_TOG;

volatile unsigned int MISC1;

volatile unsigned int MISC1_SET;

volatile unsigned int MISC1_CLR;

volatile unsigned int MISC1_TOG;

volatile unsigned int MISC2;

volatile unsigned int MISC2_SET;

volatile unsigned int MISC2_CLR;

volatile unsigned int MISC2_TOG;

} CCM_ANALOG_Type; 

/* 

 * IOMUX寄存器组

 */

typedef struct 

{

volatile unsigned int BOOT_MODE0;

volatile unsigned int BOOT_MODE1;

volatile unsigned int SNVS_TAMPER0;

volatile unsigned int SNVS_TAMPER1;

volatile unsigned int SNVS_TAMPER2;

volatile unsigned int SNVS_TAMPER3;

volatile unsigned int SNVS_TAMPER4;

volatile unsigned int SNVS_TAMPER5;

volatile unsigned int SNVS_TAMPER6;

volatile unsigned int SNVS_TAMPER7;

volatile unsigned int SNVS_TAMPER8;

volatile unsigned int SNVS_TAMPER9;

volatile unsigned int JTAG_MOD;

volatile unsigned int JTAG_TMS;

volatile unsigned int JTAG_TDO;

volatile unsigned int JTAG_TDI;

volatile unsigned int JTAG_TCK;

volatile unsigned int JTAG_TRST_B;

volatile unsigned int GPIO1_IO00;

volatile unsigned int GPIO1_IO01;

volatile unsigned int GPIO1_IO02;

volatile unsigned int GPIO1_IO03;

volatile unsigned int GPIO1_IO04;

volatile unsigned int GPIO1_IO05;

volatile unsigned int GPIO1_IO06;

volatile unsigned int GPIO1_IO07;

volatile unsigned int GPIO1_IO08;

volatile unsigned int GPIO1_IO09;

volatile unsigned int UART1_TX_DATA;

volatile unsigned int UART1_RX_DATA;

volatile unsigned int UART1_CTS_B;

volatile unsigned int UART1_RTS_B;

volatile unsigned int UART2_TX_DATA;

volatile unsigned int UART2_RX_DATA;

volatile unsigned int UART2_CTS_B;

volatile unsigned int UART2_RTS_B;

volatile unsigned int UART3_TX_DATA;

volatile unsigned int UART3_RX_DATA;

volatile unsigned int UART3_CTS_B;

volatile unsigned int UART3_RTS_B;

volatile unsigned int UART4_TX_DATA;

volatile unsigned int UART4_RX_DATA;

volatile unsigned int UART5_TX_DATA;

volatile unsigned int UART5_RX_DATA;

volatile unsigned int ENET1_RX_DATA0;

volatile unsigned int ENET1_RX_DATA1;

volatile unsigned int ENET1_RX_EN;

volatile unsigned int ENET1_TX_DATA0;

volatile unsigned int ENET1_TX_DATA1;

volatile unsigned int ENET1_TX_EN;

volatile unsigned int ENET1_TX_CLK;

volatile unsigned int ENET1_RX_ER;

volatile unsigned int ENET2_RX_DATA0;

volatile unsigned int ENET2_RX_DATA1;

volatile unsigned int ENET2_RX_EN;

volatile unsigned int ENET2_TX_DATA0;

volatile unsigned int ENET2_TX_DATA1;

volatile unsigned int ENET2_TX_EN;

volatile unsigned int ENET2_TX_CLK;

volatile unsigned int ENET2_RX_ER;

volatile unsigned int LCD_CLK;

volatile unsigned int LCD_ENABLE;

volatile unsigned int LCD_HSYNC;

volatile unsigned int LCD_VSYNC;

volatile unsigned int LCD_RESET;

volatile unsigned int LCD_DATA00;

volatile unsigned int LCD_DATA01;

volatile unsigned int LCD_DATA02;

volatile unsigned int LCD_DATA03;

volatile unsigned int LCD_DATA04;

volatile unsigned int LCD_DATA05;

volatile unsigned int LCD_DATA06;

volatile unsigned int LCD_DATA07;

volatile unsigned int LCD_DATA08;

volatile unsigned int LCD_DATA09;

volatile unsigned int LCD_DATA10;

volatile unsigned int LCD_DATA11;

volatile unsigned int LCD_DATA12;

volatile unsigned int LCD_DATA13;

volatile unsigned int LCD_DATA14;

volatile unsigned int LCD_DATA15;

volatile unsigned int LCD_DATA16;

volatile unsigned int LCD_DATA17;

volatile unsigned int LCD_DATA18;