Davinci DM6446 Linux 内核分析——board-evm.c .

/**************************************************************************

* Included Files

**************************************************************************/

#include <linux/config.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/init.h>

#include <linux/fs.h>

#include <linux/major.h>

#include <linux/root_dev.h>

#include <linux/dma-mapping.h>

#include <linux/mtd/mtd.h>

#include <linux/mtd/partitions.h>

#include <linux/serial.h>

#include <linux/usb_musb.h>

#include <linux/mtd/nand.h>

#include <linux/serial_8250.h>

#include <linux/davinci_mmc.h>

#include <linux/nand_davinci.h>

#include <asm/setup.h>

#include <asm/io.h>

#include <asm/mach-types.h>

#include <asm/mach/arch.h>

#include <asm/mach/map.h>

#include <asm/mach/flash.h>

#include <asm/arch/irqs.h>

#include <asm/arch/hardware.h>

#include <asm/arch/edma.h>

#include <linux/kgdb.h>

#include <asm/arch/cpu.h>

#include <asm/arch/mux.h>

#include "clock.h"

/*

内核在启动的时候会运行start_kernel() , 然后它会调用体系结构相关的setup_arch(&command_line), arm体系结构在arch/arm/kernel/setup.c中, 接着初始化平台相关的设备, 但在此之前, 它必须找到这块目标板的描述结构, 所以它会先通过setup_machine,其调用lookup_machine_type(nr)来查找这个结构, 参数是由u-boot传进来的, 存储在r2中. 假设它传入的是DAVINCI_EVM的nr, lookup_machine_type(nr)
就会找到本文件中到最后定义的结构体machine_desc.

start_kernel之前的linux内核启动的详细过程，可参考该文章http://blog.csdn.net/gates84/archive/2007/01/15/1483979.aspx

*/

/**************************************************************************

* Definitions

**************************************************************************/

#define DAVINCI_UART_CLK 27000000 // 串口时钟，与输入的晶振频率相同

/*

* dm644x平台采用8250兼容串口，该数据结构定义了串口的硬件资源，将填充在其platform_device结构体中，

* 即下面的serial_device中。在该platform_devic被注册后，如果其相关的驱动被注册，则会自动找到它，

* 并可调用其中的资源。plat_serial8250_port定义在include/linux/serial_8250.h文件中

*/

static struct plat_serial8250_port serial_platform_data[] = {

{

.membase = (char *)IO_ADDRESS(DAVINCI_UART0_BASE), // 串口0寄存器开始处的虚拟地址是IO_ADDRESS(0x01C20000)

.mapbase = (unsigned long)DAVINCI_UART0_BASE, // 串口0寄存器开始处的实地址是0x01C20000

.irq = IRQ_UARTINT0, // 串口0的中断号是40

.flags = UPF_BOOT_AUTOCONF | UPF_SKIP_TEST,

.iotype = UPIO_MEM32,

.regshift = 2,

.uartclk = DAVINCI_UART_CLK, // 串口时钟频率是27MHz

},

{

.flags = 0,

},

};

/* 见上述解释。platform_device定义在include/linux/device.h文件中

* 一般platform_device在系统启动的时候就注册了，而其相应到驱动platform_driver或device_driver可在模块中加载。

* http://hi.baidu.com/zengzhaonong/blog/item/440bb91e57e5251a413417d9.html 有关于platform_device结构体的详细解释

*/

static struct platform_device serial_device = {

.name = "serial8250", // 这个名字很重要，与对应驱动中的机构体device_driver中的.name相同，其被驱动模块用来查找设备

.id = 0, // 实例名后缀为0

.dev = {

.platform_data = serial_platform_data, // 设备的私有数据或资源

},

};

/* 该数据结构定义了USB的私有数据，主要是usb的类型和功能，musb_hdrc_platform_data定义在include/linux/device.h文件中 */

static struct musb_hdrc_platform_data usb_data[] = {

{

#if defined(CONFIG_USB_MUSB_OTG)

/* OTG requires a Mini-AB connector */

.mode = MUSB_OTG, // OTG类型的usb模块，既可以作usb设备也可以作主机usb使用

#elif defined(CONFIG_USB_MUSB_PERIPHERAL)

.mode = MUSB_PERIPHERAL,

#elif defined(CONFIG_USB_MUSB_HOST) // usb设备

.mode = MUSB_HOST, // 主机usb，类似于电脑的usb功能

#endif

.set_vbus = NULL,

/* irlml6401 switches 5V */

.power = 255, /* sustains 3.0+ Amps (!) */

.potpgt = 4, /* ~8 msec */

.multipoint = 1, // 1个收发端口

}, /* Need Multipoint support */

};

/* 该数据结构定义了USB的硬件资源， resource定义在include/linux/ioport.h文件中 */

static struct resource usb_resources[] = {

{

/* physical address */

.start = DAVINCI_USB_OTG_BASE, // USB_OTG寄存器起始处的实地址是0x01C20000

.end = DAVINCI_USB_OTG_BASE + 0x5ff, // USB_OTG寄存器末尾处的实地址是0x01C20000

.flags = IORESOURCE_MEM, // 标识为IO地址资源

},

{

.start = IRQ_USBINT, // USB_OTG中断号是12

.flags = IORESOURCE_IRQ, // 标识为中断资源

},

};

static u64 usb_dmamask = DMA_32BIT_MASK;

/* usb的platform_device结构体，用于注册usb设备*/

static struct platform_device usb_dev = {

.name = "musb_hdrc", // 与对应驱动中的名字相同,用于绑定驱动

.id = -1, // -1表示只有一个实例，无数字后缀

.dev = {

.platform_data = usb_data, // USB的私有数据

.dma_mask = &usb_dmamask, // 32位的dma

.coherent_dma_mask = DMA_32BIT_MASK,

},

.resource = usb_resources, // USB的硬件资源

.num_resources = ARRAY_SIZE(usb_resources),

};

/* 返回cpu的类型：DaVinci EVM*/

/**************************************************************************

* Public Functions

**************************************************************************/

int cpu_type(void)

{

return MACH_TYPE_DAVINCI_EVM;

}

/* 串口初始化，主要的工作是打开串口时钟，定义在arch/arm/mach-davinci/serial.c文件中*/

extern void davinci_serial_init(struct platform_device *pdev);

/*如果在menuconfig中配置了使用nand启动系统，则下面的的代码将会被编译。

* mtd_partition定义在include/linux/mtd/partitions.h文件中

*/

#if defined (CONFIG_MTD_NAND_DAVINCI) || defined(CONFIG_MTD_NAND_DAVINCI_MODULE)

static struct mtd_partition nand_partitions[] = {

/* bootloader (U-Boot, etc) in first sector */

{

.name = "bootloader", // bootloader，一般使用u-boot

.offset = 0, // 从mtd分区开始地址的偏移量是0

.size = SZ_256K, // 分区大小是256K

.mask_flags = 0, /* force read-only */ // 只读

},

/* bootloader params in the next sector */

{

.name = "params", // 存放bootloader的参数

.offset = MTDPART_OFS_APPEND, // 从上一分区（bootloader分区）开始

.size = SZ_128K,

.mask_flags = MTD_WRITEABLE, /* force read-only */ // 可写

},

/* kernel */

{

.name = "kernel", // 存放内核

.offset = MTDPART_OFS_APPEND,

.size = SZ_4M,

.mask_flags = 0,

},

/* file system */

{

.name = "filesystem", // 存放文件系统

.offset = MTDPART_OFS_APPEND,

.size = MTDPART_SIZ_FULL, // 整个分区的剩余存储空间

.mask_flags = 0,

}

};

/* nand platform device 私有数据，用于描述nand flash banks

* nand_davinci_platform_data定义在include/linux/nand_davinci.h文件中

*/

static struct nand_davinci_platform_data nand_data = {

.options = 0,

.eccmode = NAND_ECC_HW3_512, // 校验模式

.cle_mask = 0x10,

.ale_mask = 0x08,

.bbt_td = NULL,

.bbt_md = NULL,

.parts = nand_partitions, // 分区信息

.nr_parts = ARRAY_SIZE(nand_partitions),

};

/* 定义了nand设备使用的硬件资源 */

static struct resource nand_resources[] = {

[0] = { /* First memory resource is AEMIF control registers */

.start = DM644X_ASYNC_EMIF_CNTRL_BASE,

.end = DM644X_ASYNC_EMIF_CNTRL_BASE + SZ_4K - 1,

.flags = IORESOURCE_MEM,

},

[1] = { /* Second memory resource is NAND I/O window */

.start = DAVINCI_ASYNC_EMIF_DATA_CE0_BASE,

.end = DAVINCI_ASYNC_EMIF_DATA_CE0_BASE + SZ_16K - 1,

.flags = IORESOURCE_MEM,

},

};

/* nand platform_device ,用于注册nand device到platform总线 */

static struct platform_device nand_device = {

.name = "nand_davinci",

.id = 0,

.dev = {

.platform_data = &nand_data,

},

.num_resources = ARRAY_SIZE(nand_resources),

.resource = nand_resources,

};

#endif

/*如果在menuconfig中配置了使用nor启动系统，则下面的的代码将会被编译。

* mtd_partition定义在include/linux/mtd/partitions.h文件中

*/

#if defined (CONFIG_MTD_DAVINCI_NOR) || defined(CONFIG_MTD_DAVINCI_NOR_MODULE)

static struct mtd_partition davinci_evm_nor_partitions[] = {

/* bootloader (U-Boot, etc) in first sector */

{

.name = "bootloader",

.offset = 0,

.size = SZ_128K,

.mask_flags = 0

},

/* bootloader params in the next sector */

{

.name = "params",

.offset = MTDPART_OFS_APPEND,

.size = SZ_128K,

.mask_flags = MTD_WRITEABLE, /* force read-only */

},

/* kernel */

{

.name = "kernel",

.offset = MTDPART_OFS_APPEND,

.size = SZ_4M,

.mask_flags = 0

},

/*cramfs file system */

{

.name = "cramfs",

.offset = MTDPART_OFS_APPEND,

.size = SZ_2M,

.mask_flags = 0

},

/* jffs2 file system */

{

.name = "jffs2", // jffs2文件分区

.offset = MTDPART_OFS_APPEND,

.size = MTDPART_SIZ_FULL,

.mask_flags = 0

}

};

/* nor platform device 私有数据，用于描述nor flash banks

* flash_platform_data定义在include/asm-arm/mach/flash.h文件中

*/

static struct flash_platform_data davinci_evm_flash_data = {

.map_name = "cfi_probe",

.width = 2,

.parts = davinci_evm_nor_partitions,

.nr_parts = ARRAY_SIZE(davinci_evm_nor_partitions),

};

/* 定义了nor设备使用的硬件资源 */

/* NOTE: CFI probe will correctly detect flash part as 32M, but EMIF

;* limits addresses to 16M, so using addresses past 16M will wrap */

static struct resource davinci_evm_flash_resource = {

.start = DAVINCI_ASYNC_EMIF_DATA_CE0_BASE,

.end = DAVINCI_ASYNC_EMIF_DATA_CE0_BASE + SZ_16M - 1,

.flags = IORESOURCE_MEM,

};

/* nor platform_device ,用于注册nor device到platform总线 */

static struct platform_device davinci_evm_flash_device = {

.name = "nor_davinci",

.id = 0,

.dev = {

.platform_data = &davinci_evm_flash_data,

},

.num_resources = 1,

.resource = &davinci_evm_flash_resource,

};

#endif

/* 定义了mmc设备使用的硬件资源 */

#if defined(CONFIG_MMC_DAVINCI) || defined(CONFIG_MMC_DAVINCI_MODULE)

static struct resource mmc0_resources[] = {

[0] = { /* registers */ // 寄存器

.start = DAVINCI_MMC_SD_BASE,

.end = DAVINCI_MMC_SD_BASE + SZ_1K - 1,

.flags = IORESOURCE_MEM,

},

[1] = { /* interrupt */ // 中断号

.start = IRQ_MMCINT,

.end = IRQ_MMCINT,

.flags = IORESOURCE_IRQ,

},

[2] = { /* dma rx */ // dma 接收寄存器

.start = DAVINCI_DMA_MMCRXEVT,

.end = DAVINCI_DMA_MMCRXEVT,

.flags = IORESOURCE_DMA,

},

[3] = { /* dma tx */ // dma 发送寄存器

.start = DAVINCI_DMA_MMCTXEVT,

.end = DAVINCI_DMA_MMCTXEVT,

.flags = IORESOURCE_DMA,

},

};

/* mmc platform device 私有数据，用于描述mmc flash banks

* davinci_mmc_platform_data定义在include/linux/davinci_mmc.h文件中

*/

static struct davinci_mmc_platform_data mmc0_platform_data = {

.mmc_clk = "MMCSDCLK0", // 用于获mmc取时钟

.rw_threshold = 32,

.use_4bit_mode = 1,

};

/* mmc platform_device ,用于注册mmc0_device到platform总线 */

static struct platform_device mmc0_device = {

.name = "mmc",

.id = 0,

.dev = {

.platform_data = &mmc0_platform_data,

},

.num_resources = ARRAY_SIZE(mmc0_resources),

.resource = mmc0_resources,

};

/* 开启mmc模块的电源*/

static void setup_mmc(void)

{

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_MMC_SD0, 1);

}

#else

#define setup_mmc()

#endif

/* platform_device指针数组 */

static struct platform_device *davinci_evm_devices[] __initdata = {

&serial_device,

&usb_dev,

#if defined (CONFIG_MTD_NAND_DAVINCI) || defined(CONFIG_MTD_NAND_DAVINCI_MODULE)

&nand_device,

#endif

#if defined (CONFIG_MTD_DAVINCI_NOR) || defined(CONFIG_MTD_DAVINCI_NOR_MODULE)

&davinci_evm_flash_device,

#endif

#if defined(CONFIG_MMC_DAVINCI) || defined(CONFIG_MMC_DAVINCI_MODULE)

&mmc0_device,

#endif

};

/* 用于设置fiq,irq 的优先级*/

/* FIQ are pri 0-1; otherwise 2-7, with 7 lowest priority */

static const u8 dm644x_default_priorities[DAVINCI_N_AINTC_IRQ] = {

[IRQ_VDINT0] = 2,

[IRQ_VDINT1] = 6,

[IRQ_VDINT2] = 6,

[IRQ_HISTINT] = 6,

[IRQ_H3AINT] = 6,

[IRQ_PRVUINT] = 6,

[IRQ_RSZINT] = 6,

[IRQ_VFOCINT] = 7,

[IRQ_VENCINT] = 6,

[IRQ_ASQINT] = 6,

[IRQ_IMXINT] = 6,

[IRQ_VLCDINT] = 6,

[IRQ_USBINT] = 4,

[IRQ_EMACINT] = 4,

[IRQ_IEEE1394INT] = 7,

[IRQ_IEEE1394WK] = 7,

[IRQ_CCINT0] = 5, /* dma */

[IRQ_CCERRINT] = 5, /* dma */

[IRQ_TCERRINT0] = 5, /* dma */

[IRQ_TCERRINT] = 5, /* dma */

[IRQ_PSCINT] = 7,

[21] = 7,

[IRQ_IDE] = 4,

[IRQ_HPIINT] = 7,

[IRQ_MBXINT] = 7,

[IRQ_MBRINT] = 7,

[IRQ_MMCINT] = 7,

[IRQ_SDIOINT] = 7,

[IRQ_HPIINT] = 7,

[IRQ_DDRINT] = 7,

[IRQ_AEMIFINT] = 7,

[IRQ_VLQINT] = 4,

[IRQ_TINT0_TINT12] = 2, /* clockevent */

[IRQ_TINT0_TINT34] = 2, /* clocksource */

[IRQ_TINT1_TINT12] = 7, /* DSP timer */

[IRQ_TINT1_TINT34] = 7, /* system tick */

[IRQ_PWMINT0] = 7,

[IRQ_PWMINT1] = 7,

[IRQ_PWMINT2] = 7,

[IRQ_I2C] = 3,

[IRQ_UARTINT0] = 3,

[IRQ_UARTINT1] = 3,

[IRQ_UARTINT2] = 3,

[IRQ_SPINT0] = 3,

[IRQ_SPINT1] = 3,

[45] = 7,

[IRQ_DSP2ARM0] = 4,

[IRQ_DSP2ARM1] = 4,

[IRQ_GPIO0] = 7,

[IRQ_GPIO1] = 7,

[IRQ_GPIO2] = 7,

[IRQ_GPIO3] = 7,

[IRQ_GPIO4] = 7,

[IRQ_GPIO5] = 7,

[IRQ_GPIO6] = 7,

[IRQ_GPIO7] = 7,

[IRQ_GPIOBNK0] = 7,

[IRQ_GPIOBNK1] = 7,

[IRQ_GPIOBNK2] = 7,

[IRQ_GPIOBNK3] = 7,

[IRQ_GPIOBNK4] = 7,

[IRQ_COMMTX] = 7,

[IRQ_COMMRX] = 7,

[IRQ_EMUINT] = 7,

};

/* davinci平台初始化，主要是开启各模块到电源。dm644x平台到电源管理是分模块到，不使用到时候关掉，可降低功耗。

* 所以需要使用哪个模块，必须在程序中打开，打开后才能设置相应的寄存器。

*/

static void board_init(void)

{

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_VLYNQ, 1);

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_VPSSMSTR, 1);

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_VPSSSLV, 1);

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_TPCC, 1);

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_TPTC0, 1);

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_TPTC1, 1);

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_GPIO, 1);

/* Turn on WatchDog timer LPSC. Needed for RESET to work */

board_setup_psc(DAVINCI_GPSC_ARMDOMAIN, DAVINCI_LPSC_TIMER2, 1);

davinci_serial_init(&serial_device); // 初始化串口

}

/* dm644x平台许多功能模块到引脚是gpio复用到，功能引脚和gpio脚是互斥的 ，

* 该函数用来设置这些引脚.

*/

static void dm644x_setup_pinmux(unsigned int id)

{

switch (id) {

case DAVINCI_LPSC_ATA:

davinci_cfg_reg(DM644X_HDIREN);

davinci_cfg_reg(DM644X_ATAEN);

break;

case DAVINCI_LPSC_MMC_SD0:

/* VDD power manipulations are done in U-Boot for CPMAC

* so applies to MMC as well

*/

/*Set up the pull register for MMC */

DAVINCI_VDD3P3V_PWDN = 0x0;

davinci_cfg_reg(DM644X_MSTK);

break;

case DAVINCI_LPSC_I2C:

davinci_cfg_reg(DM644X_I2C);

break;

case DAVINCI_LPSC_McBSP0:

davinci_cfg_reg(DM644X_MCBSP0);

break;

case DAVINCI_LPSC_PWM0:

davinci_cfg_reg(DM644X_PWM0);

break;

case DAVINCI_LPSC_PWM1:

davinci_cfg_reg(DM644X_PWM1);

break;

case DAVINCI_LPSC_PWM2:

davinci_cfg_reg(DM644X_PWM2);

break;

case DAVINCI_LPSC_VLYNQ:

davinci_cfg_reg(DM644X_VLINQEN);

davinci_cfg_reg(DM644X_VLINQWD);

break;

default:

break;

}

}

/* 用于设置各中断的优先级，

* 该指针定义在arch/arm/mach-davinci/irq.c中

*/

extern const u8 *davinci_def_priorities;

/* 初始化IO口，开启各模块电源 */

static void __init davinci_map_io(void)

{

davinci_pinmux_setup = dm644x_setup_pinmux;

davinci_def_priorities = dm644x_default_priorities;

davinci_map_common_io();

#ifdef CONFIG_KGDB_8250

early_serial_setup((struct uart_port *)

&serial_platform_data[kgdb8250_ttyS]);

kgdb8250_add_platform_port(kgdb8250_ttyS,

&serial_platform_data[kgdb8250_ttyS]);

#endif

/* Initialize the DaVinci EVM board settigs */

board_init ();

}

/* 初始化平台irq，该函数在arch/arm/mach-davinci/irq.c中定义 */

int __init davinci_gpio_irq_setup(void);

void davinci_msp430_deep_sleep(void)

{

unsigned int icstr = DAVINCI_I2C_BASE + 0x08;

unsigned int icsar = DAVINCI_I2C_BASE + 0x1C;

unsigned int iccnt = DAVINCI_I2C_BASE + 0x14;

unsigned int icdxr = DAVINCI_I2C_BASE + 0x20;

unsigned int icmdr = DAVINCI_I2C_BASE + 0x24;

u32 cnt = 0, buflen = 2;

char rtcdata[2] = { 2, 8 };

char *buffer = rtcdata;

/* check for bus busy */

while (readl(icstr) & 0x1000) ;

/* configure the count register */

writel(2, iccnt);

/* set the salve address */

writel(0x23, icsar);

/* Take I2C out of reset, configure it as master,

* set the start bit, stop bit and enable the

* transmitter */

writel(0x2e20, icmdr);

while (cnt < buflen) {

if ((readl(icstr) & 0x0010) != 0) {

writel(*buffer, icdxr);

++buffer;

++cnt;

}

}

}

/* 该驱动的初始化函数 */

static __init void evm_init(void)

{

#if defined (CONFIG_MTD_DAVINCI_NOR) || defined(CONFIG_MTD_DAVINCI_NOR_MODULE)

#if defined(CONFIG_BLK_DEV_DAVINCI) || defined(CONFIG_BLK_DEV_DAVINCI_MODULE)

#warning IDE and NOR flash are are pin-muxed. Disable IDE or NOR.

printk(KERN_WARNING "WARNING: both IDE and NOR flash are enabled, "

"but are pin-muxed.\n\t Disable IDE or NOR support.\n");

#endif

#if defined (CONFIG_MTD_NAND_DAVINCI) || defined(CONFIG_MTD_NAND_DAVINCI_MODULE)

#warning NAND and NOR flash are are pin-muxed. Disable NAND or NOR.

printk(KERN_WARNING "WARNING: both NAND and NOR flash are enabled, "

"but are pin-muxed.\n\t Disable NAND or NOR support.\n");

#endif

#endif

#if defined(CONFIG_BLK_DEV_DAVINCI) || defined(CONFIG_BLK_DEV_DAVINCI_MODULE)

#if defined (CONFIG_MTD_NAND_DAVINCI) || defined(CONFIG_MTD_NAND_DAVINCI_MODULE)

#warning IDE and NAND flash are are pin-muxed. Disable IDE or NAND.

printk(KERN_WARNING "WARNING: both IDE and NAND flash are enabled, "

"but are pin-muxed.\n\t Disable IDE or NAND support.\n");

#endif

#endif

pm_power_off = davinci_msp430_deep_sleep;

setup_mmc();

davinci_gpio_irq_setup();

platform_add_devices(davinci_evm_devices, // 注册所有已定义的platform_device

ARRAY_SIZE(davinci_evm_devices));

}

/* 初始化ARM中断控制寄存器函数

* 在arch/arm/mach-davinci/irq.c文件中定义

*/

extern void davinci_irq_init(void);

/* 系统定时器结构体，用于初始化平台的定时器 */

extern struct sys_timer davinci_timer;

/* 定义平台属性，MACHINE_START是个宏定义，用于填充平台描述符结构体machine_desc

* 它们都在include/asm-arm/mach-davinci/arch.h中定义

*

*/

MACHINE_START(DAVINCI_EVM, "DaVinci EVM")

MAINTAINER("Texas Instruments, PSP Team")

BOOT_MEM(DAVINCI_DDR_BASE, IO_PHYS, IO_VIRT) // 定义了DDR2的起始物理地址，IO寄存器的起始物理地址以及IO寄存器的到虚拟地址

BOOT_PARAMS(0x80000100) // bootloader存放启动参数到起始物理地址，系统启动会从中读取各种参数

MAPIO(davinci_map_io) // IO模块初始化，定义在本文件中

INITIRQ(davinci_irq_init)

.timer = &davinci_timer,

INIT_MACHINE(evm_init)

MACHINE_END

EXPORT_SYMBOL(cpu_type)