U-Boot的设备管理
U-Boot的设备管理
目录
一、初始设备链表、初始化设备和注册设备
1.1 devices_init函数
1.2 devices结构的定义
1.3 drv_system_init 函数
二、设备注册
2.1 device_register (device_t * dev)
2.2 device_deregister(char *devname)
三、设备搜索
1.1 devices_init函数
1.2 devices结构的定义
1.3 drv_system_init 函数
二、设备注册
2.1 device_register (device_t * dev)
2.2 device_deregister(char *devname)
三、设备搜索
U-Boot通过devices_init函数创建设备链表，然后在devices_init函数中初始化设备并将设备添加到设备链表中。U-Boot使用devices_t结构体来管理设备，设备链表也就是devices_t结构体的链表。通过i2c_init、drv_lcd_init、drv_video_init、drv_keyboard_init、drv_logbuff_init、drv_system_init、serial_devices_init、drv_usbtty_init和drv_nc_init函数初始化设备(这些函数是否执行是通过宏来决定的)，并通过device_register函数注册设备。
一、初始设备链表、初始化设备和注册设备
U-Boot在第二阶段中通过devices_init函数创建设备链表，初始化设备并将其注册到设备链表中。该函数在common/devices.c文件中，其对应的头文件是nclude/devices.h。
1.1 devices_init函数
int devices_init (void)
{
#ifndef CONFIG_ARM /* already relocated for current ARM implementation */
ulong relocation_offset = gd->reloc_off;
int i;
/* relocate device name pointers */
for (i = 0; i < (sizeof (stdio_names) / sizeof (char *)); ++i) {
stdio_names[i] = (char *) (((ulong) stdio_names[i]) +
relocation_offset);
}
#endif
/* Initialize the list */
devlist = ListCreate (sizeof (device_t));//创建设备列表
if (devlist == NULL) {
eputs ("Cannot initialize the list of devices!\n");
return -1;
}
#if defined(CONFIG_HARD_I2C) || defined(CONFIG_SOFT_I2C)
i2c_init (CFG_I2C_SPEED, CFG_I2C_SLAVE);//初始化i2c接口，i2c没有注册到devlist中去
#endif
#ifdef CONFIG_LCD
drv_lcd_init ();
#endif
#if defined(CONFIG_VIDEO) || defined(CONFIG_CFB_CONSOLE)
drv_video_init ();
#endif
#ifdef CONFIG_KEYBOARD
drv_keyboard_init ();
#endif
#ifdef CONFIG_LOGBUFFER
drv_logbuff_init ();
#endif
drv_system_init ();//这里其实是定义了一个串口设备，并且注册到devlist中
#ifdef CONFIG_SERIAL_MULTI
serial_devices_init ();
#endif
#ifdef CONFIG_USB_TTY
drv_usbtty_init ();
#endif
#ifdef CONFIG_NETCONSOLE
drv_nc_init ();
#endif
return (0);
}
经过devices_init()，创建了devlist，但是只有一个串口设备注册在内。
1.2 devices结构的定义
/* Device information */
typedef struct {
int flags; /* Device flags: input/output/system */
int ext; /* Supported extensions */
char name[16]; /* Device name 设备名称 */
/* GENERAL functions 启动和停止函数 */
int (*start) (void); /* To start the device */
int (*stop) (void); /* To stop the device */
/* OUTPUT functions 输出函数 */
void (*putc) (const char c); /* To put a char */
void (*puts) (const char *s); /* To put a string (accelerator) */
/* INPUT functions 输入函数*/
int (*tstc) (void); /* To test if a char is ready... */
int (*getc) (void); /* To get that char */
/* Other functions */
void *priv; /* Private extensions */
} device_t;
1.3 drv_system_init 函数
drv_system_init 函数初始化串口设备，源码如下：
static void drv_system_init (void)
{
device_t dev;//定义一个结构体
memset (&dev, 0, sizeof (dev));//为刚刚定义的结构体分配内存
strcpy (dev.name, "serial");//名称
dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
#ifdef CONFIG_SERIAL_SOFTWARE_FIFO
dev.putc = serial_buffered_putc;
dev.puts = serial_buffered_puts;
dev.getc = serial_buffered_getc;
dev.tstc = serial_buffered_tstc;
#else
dev.putc = serial_putc;
dev.puts = serial_puts;
dev.getc = serial_getc;
dev.tstc = serial_tstc;
#endif
device_register (&dev);//注册函数
#ifdef CFG_DEVICE_NULLDEV
memset (&dev, 0, sizeof (dev));
strcpy (dev.name, "nulldev");
dev.flags = DEV_FLAGS_OUTPUT | DEV_FLAGS_INPUT | DEV_FLAGS_SYSTEM;
dev.putc = nulldev_putc;
dev.puts = nulldev_puts;
dev.getc = nulldev_input;
dev.tstc = nulldev_input;
device_register (&dev);
#endif
}
二、设备注册
有连个设备注册函数，一个的参数时devces结构体，另一个的参数是设备的名称
2.1 device_register (device_t * dev)
设备注册，将结构体添加到devlist的后面，device_register函数的源码如下：
int device_register (device_t * dev)
{
ListInsertItem (devlist, dev, LIST_END);
return 0;
}
/*******************************/
/*
* returns 1 if the item is inserted, returns 0 if out of memory or
* bad arguments were passed.
*/
int ListInsertItem (list_t list, void *ptrToItem, int itemPosition)
{
return ListInsertItems (list, ptrToItem, itemPosition, 1);
}
/*******************************/
int ListInsertItems (list_t list, void *ptrToItems, int firstItemPosition,
int numItemsToInsert)
{
int numItems = (*list)->numItems;
if (firstItemPosition == numItems + 1)
firstItemPosition = LIST_END;
else if (firstItemPosition > numItems)
return 0;
if ((*list)->numItems >= (*list)->listSize) {
if (!ExpandListSpace (list, -numItemsToInsert))
return 0;
}
if (firstItemPosition == LIST_START) {
if (numItems == 0) {
/* special case for empty list */
firstItemPosition = LIST_END;
} else {
firstItemPosition = 1;
}
}
if (firstItemPosition == LIST_END) { /* add at the end of the list */
if (ptrToItems)
memcpy (ITEMPTR (list, numItems), ptrToItems,
(*list)->itemSize * numItemsToInsert);
else
memset (ITEMPTR (list, numItems), 0,
(*list)->itemSize * numItemsToInsert);
(*list)->numItems += numItemsToInsert;
} else { /* move part of list up to make room for new item */
memmove (ITEMPTR (list, firstItemPosition - 1 + numItemsToInsert),
ITEMPTR (list, firstItemPosition - 1),
(numItems + 1 - firstItemPosition) * (*list)->itemSize);
if (ptrToItems)
memmove (ITEMPTR (list, firstItemPosition - 1), ptrToItems,
(*list)->itemSize * numItemsToInsert);
else
memset (ITEMPTR (list, firstItemPosition - 1), 0,
(*list)->itemSize * numItemsToInsert);
(*list)->numItems += numItemsToInsert;
}
return 1;
}
2.2 device_deregister(char *devname)
int device_deregister(char *devname)
{
int i,l,dev_index;
device_t *dev = NULL;
char temp_names[3][8];
dev_index=-1;
for (i=1; i<=ListNumItems(devlist); i++) {
dev = ListGetPtrToItem (devlist, i);
if(strcmp(dev->name,devname)==0) {
dev_index=i;
break;
}
}
if(dev_index<0) /* device not found */
return 0;
/* get stdio devices (ListRemoveItem changes the dev list) */
for (l=0 ; l< MAX_FILES; l++) {
if (stdio_devices[l] == dev) {
/* Device is assigned -> report error */
return -1;
}
memcpy (&temp_names[l][0],
stdio_devices[l]->name,
sizeof(stdio_devices[l]->name));
}
ListRemoveItem(devlist,NULL,dev_index);
/* reassign Device list */
for (i=1; i<=ListNumItems(devlist); i++) {
dev = ListGetPtrToItem (devlist, i);
for (l=0 ; l< MAX_FILES; l++) {
if(strcmp(dev->name,temp_names[l])==0) {
stdio_devices[l] = dev;
}
}
}
return 0;
}
三、设备搜索
/* search a device */
device_t *search_device (int flags, char *name)
{
int i, items;
device_t *dev = NULL;
items = ListNumItems (devlist);
if (name == NULL)
return dev;
for (i = 1; i <= items; i++) {
dev = ListGetPtrToItem (devlist, i);
if ((dev->flags & flags) && (strcmp (name, dev->name) == 0)) {
break;
}
}
return dev;
}