Uboot驱动框架
系列 - boot
目录
u-boot源码阅读:驱动框架
代码位置: u-boot/drivers/core
1 驱动模型
在U-boot中引入驱动模型(driver model)，为驱动的定义和范文接口提供统一的方法，提高驱动间的兼容性以及访问的标准 性，u-boot中的驱动模型(DM)和kernel中的设备驱动模型类似，但是也有所区别
U-Boot采用了一种分层的设备模型来管理硬件资源。这个模型包括了设备（device）、总线（bus）、驱动（driver）以及类（class）的概念。每个设备都连接到一个总线上，而每个驱动则与一种类型的设备相对应。
设备(Device)：代表系统中的物理或虚拟硬件。 总线(Bus)：定义了如何枚举和配置连接在其上的设备。 驱动(Driver)：包含了操作特定类型设备的代码。 类(Class)：用于分类相似功能的设备，如USB、I2C等。
1.1 uclass/udevices/drivers三者直接的关联
uclass可以理解为具有相同属性的device对外操作的接口, 它与上层接口直接通讯，其驱动为uclass_driver，给上层提供接口 udevice对具体设备的抽象，对应的驱动是driver; driver负责和硬件通讯，为uclass提供实际的操作集 udevice如何和uclass绑定：udevice对应的driver_id和uclass对应的uclass_driver_id是否匹配 hardware对应的driver绑定对应的udevice，udevice绑定uclass，uclass有其对应的uclass_driver
uclass和udevice是动态生成的
- udevice在解析fdt中的设备的时候自动生成，然后udevice找到对应的driver
- driver中保存了uclass_id， 根据它找到uclass_driver_id
- 从uclass链表中查找对应的uclass是否已经生成，若没有生成，则动态生成
- 重点是解析设备树，生成udevice， 并找到对应的driver
graph TD uclass --> udevice1 udevice1 --> driver1 driver1 --> hardware1 uclass --> udevice2 udevice2 --> driver2 driver2 --> hardware2 uclass --> udevice3 udevice3 --> driver3 driver3 --> hardware3 uclass --> udevice4 udevice4 --> driver4 driver4 --> hardware4 uclass --> uclass_driver
2 uclass
uclass有对应的ID号，定义在其uclass_driver中,存在于include/dm/uclass-id.h文件中
enum uclass_id {
/* These are used internally by driver model */
UCLASS_ROOT = 0,
UCLASS_DEMO,
UCLASS_TEST,
UCLASS_TEST_FDT,
UCLASS_TEST_FDT_MANUAL,
UCLASS_TEST_BUS,
UCLASS_TEST_PROBE,
UCLASS_TEST_DUMMY,
UCLASS_TEST_DEVRES,
UCLASS_TEST_ACPI,
UCLASS_SPI_EMUL, /* sandbox SPI device emulator */
UCLASS_I2C_EMUL, /* sandbox I2C device emulator */
UCLASS_I2C_EMUL_PARENT, /* parent for I2C device emulators */
UCLASS_PCI_EMUL, /* sandbox PCI device emulator */
UCLASS_PCI_EMUL_PARENT, /* parent for PCI device emulators */
UCLASS_USB_EMUL, /* sandbox USB bus device emulator */
UCLASS_AXI_EMUL, /* sandbox AXI bus device emulator */
/* U-Boot uclasses start here - in alphabetical order */
UCLASS_ACPI_PMC, /* (x86) Power-management controller (PMC) */
UCLASS_ADC, /* Analog-to-digital converter */
UCLASS_AHCI, /* SATA disk controller */
UCLASS_AUDIO_CODEC, /* Audio codec with control and data path */
UCLASS_AXI, /* AXI bus */
UCLASS_BLK, /* Block device */
UCLASS_BLKMAP, /* Composable virtual block device */
UCLASS_BOOTCOUNT, /* Bootcount backing store */
UCLASS_BOOTDEV, /* Boot device for locating an OS to boot */
UCLASS_BOOTMETH, /* Bootmethod for booting an OS */
UCLASS_BOOTSTD, /* Standard boot driver */
UCLASS_BUTTON, /* Button */
UCLASS_CACHE, /* Cache controller */
UCLASS_CLK, /* Clock source, e.g. used by peripherals */
UCLASS_CPU, /* CPU, typically part of an SoC */
UCLASS_CROS_EC, /* Chrome OS EC */
UCLASS_DISPLAY, /* Display (e.g. DisplayPort, HDMI) */
UCLASS_DMA, /* Direct Memory Access */
UCLASS_DSA, /* Distributed (Ethernet) Switch Architecture */
UCLASS_DSI_HOST, /* Display Serial Interface host */
UCLASS_ECDSA, /* Elliptic curve cryptographic device */
UCLASS_EFI_LOADER, /* Devices created by UEFI applications */
UCLASS_EFI_MEDIA, /* Devices provided by UEFI firmware */
UCLASS_ETH, /* Ethernet device */
UCLASS_ETH_PHY, /* Ethernet PHY device */
UCLASS_EXTCON, /* External Connector Class */
UCLASS_FIRMWARE, /* Firmware */
UCLASS_FPGA, /* FPGA device */
UCLASS_FUZZING_ENGINE, /* Fuzzing engine */
UCLASS_FS_FIRMWARE_LOADER, /* Generic loader */
UCLASS_FWU_MDATA, /* FWU Metadata Access */
UCLASS_GPIO, /* Bank of general-purpose I/O pins */
UCLASS_HASH, /* Hash device */
UCLASS_HWSPINLOCK, /* Hardware semaphores */
UCLASS_HOST, /* Sandbox host device */
UCLASS_I2C, /* I2C bus */
UCLASS_I2C_EEPROM, /* I2C EEPROM device */
UCLASS_I2C_GENERIC, /* Generic I2C device */
UCLASS_I2C_MUX, /* I2C multiplexer */
UCLASS_I2S, /* I2S bus */
UCLASS_IDE, /* IDE device */
UCLASS_IOMMU, /* IOMMU */
UCLASS_IRQ, /* Interrupt controller */
UCLASS_KEYBOARD, /* Keyboard input device */
UCLASS_LED, /* Light-emitting diode (LED) */
UCLASS_LPC, /* x86 'low pin count' interface */
UCLASS_MAILBOX, /* Mailbox controller */
UCLASS_MASS_STORAGE, /* Mass storage device */
UCLASS_MDIO, /* MDIO bus */
UCLASS_MDIO_MUX, /* MDIO MUX/switch */
UCLASS_MEMORY, /* Memory Controller device */
UCLASS_MISC, /* Miscellaneous device */
UCLASS_MMC, /* SD / MMC card or chip */
UCLASS_MOD_EXP, /* RSA Mod Exp device */
UCLASS_MTD, /* Memory Technology Device (MTD) device */
UCLASS_MUX, /* Multiplexer device */
UCLASS_NOP, /* No-op devices */
UCLASS_NORTHBRIDGE, /* Intel Northbridge / SDRAM controller */
UCLASS_NVME, /* NVM Express device */
UCLASS_NVMXIP, /* NVM XIP devices */
UCLASS_P2SB, /* (x86) Primary-to-Sideband Bus */
UCLASS_PANEL, /* Display panel, such as an LCD */
UCLASS_PANEL_BACKLIGHT, /* Backlight controller for panel */
UCLASS_PARTITION, /* Logical disk partition device */
UCLASS_PCH, /* x86 platform controller hub */
UCLASS_PCI, /* PCI bus */
UCLASS_PCI_EP, /* PCI endpoint device */
UCLASS_PCI_GENERIC, /* Generic PCI bus device */
UCLASS_PHY, /* Physical Layer (PHY) device */
UCLASS_PINCONFIG, /* Pin configuration node device */
UCLASS_PINCTRL, /* Pinctrl (pin muxing/configuration) device */
UCLASS_PMIC, /* PMIC I/O device */
UCLASS_POWER_DOMAIN, /* (SoC) Power domains */
UCLASS_PVBLOCK, /* Xen virtual block device */
UCLASS_PWM, /* Pulse-width modulator */
UCLASS_PWRSEQ, /* Power sequence device */
UCLASS_QFW, /* QEMU firmware config device */
UCLASS_RAM, /* RAM controller */
UCLASS_REBOOT_MODE, /* Reboot mode */
UCLASS_REGULATOR, /* Regulator device */
UCLASS_REMOTEPROC, /* Remote Processor device */
UCLASS_RESET, /* Reset controller device */
UCLASS_RNG, /* Random Number Generator */
UCLASS_RTC, /* Real time clock device */
UCLASS_SCMI_AGENT, /* Interface with an SCMI server */
UCLASS_SCSI, /* SCSI device */
UCLASS_SERIAL, /* Serial UART */
UCLASS_SIMPLE_BUS, /* Bus with child devices */
UCLASS_SMEM, /* Shared memory interface */
UCLASS_SOC, /* SOC Device */
UCLASS_SOUND, /* Playing simple sounds */
UCLASS_SPI, /* SPI bus */
UCLASS_SPI_FLASH, /* SPI flash */
UCLASS_SPI_GENERIC, /* Generic SPI flash target */
UCLASS_SPMI, /* System Power Management Interface bus */
UCLASS_SYSCON, /* System configuration device */
UCLASS_SYSINFO, /* Device information from hardware */
UCLASS_SYSRESET, /* System reset device */
UCLASS_TEE, /* Trusted Execution Environment device */
UCLASS_THERMAL, /* Thermal sensor */
UCLASS_TIMER, /* Timer device */
UCLASS_TPM, /* Trusted Platform Module TIS interface */
UCLASS_UFS, /* Universal Flash Storage */
UCLASS_USB, /* USB bus */
UCLASS_USB_DEV_GENERIC, /* USB generic device */
UCLASS_USB_HUB, /* USB hub */
UCLASS_USB_GADGET_GENERIC, /* USB generic device */
UCLASS_VIDEO, /* Video or LCD device */
UCLASS_VIDEO_BRIDGE, /* Video bridge, e.g. DisplayPort to LVDS */
UCLASS_VIDEO_CONSOLE, /* Text console driver for video device */
UCLASS_VIDEO_OSD, /* On-screen display */
UCLASS_VIRTIO, /* VirtIO transport device */
UCLASS_W1, /* Dallas 1-Wire bus */
UCLASS_W1_EEPROM, /* one-wire EEPROMs */
UCLASS_WDT, /* Watchdog Timer driver */
UCLASS_COUNT,
UCLASS_INVALID = -1,
};2.1 定义uclass_driver
#define UCLASS_DRIVER(__name) ll_entry_declare(struct uclass_driver, __name, uclass_driver)
#define ll_entry_declare(_type, _name, _list) \
_type _u_boot_list_2_##_list##_2_##_name __aligned(4) \
__attribute__((unused)) \
__section("__u_boot_list_2_"#_list"_2_"#_name)
struct uclass_driver {
const char *name;
enum uclass_id id;
int (*post_bind)(struct udevice *dev);
int (*pre_unbind)(struct udevice *dev);
int (*pre_probe)(struct udevice *dev);
int (*post_probe)(struct udevice *dev);
int (*pre_remove)(struct udevice *dev);
int (*child_post_bind)(struct udevice *dev);
int (*child_pre_probe)(struct udevice *dev);
int (*child_post_probe)(struct udevice *dev);
int (*init)(struct uclass *class);
int (*destroy)(struct uclass *class);
int priv_auto;
int per_device_auto;
int per_device_plat_auto;
int per_child_auto;
int per_child_plat_auto;
uint32_t flags;
};生成结果如下
__u_boot_list_2_uclass_driver_1
0x000b277c 0x0 drivers/core/lists.o
__u_boot_list_2_uclass_driver_1
0x000b277c 0x0 drivers/core/root.o
__u_boot_list_2_uclass_driver_2_ahci
0x000b277c 0x48 drivers/ata/ahci-uclass.o
0x000b277c _u_boot_list_2_uclass_driver_2_ahci
__u_boot_list_2_uclass_driver_2_blk
0x000b27c4 0x48 drivers/block/blk-uclass.o
0x000b27c4 _u_boot_list_2_uclass_driver_2_blk
__u_boot_list_2_uclass_driver_2_bootdev
0x000b280c 0x48 boot/bootdev-uclass.o
0x000b280c _u_boot_list_2_uclass_driver_2_bootdev
__u_boot_list_2_uclass_driver_2_bootmeth
0x000b2854 0x48 boot/bootmeth-uclass.o
0x000b2854 _u_boot_list_2_uclass_driver_2_bootmeth
__u_boot_list_2_uclass_driver_2_bootstd
0x000b289c 0x48 boot/bootstd-uclass.o
0x000b289c _u_boot_list_2_uclass_driver_2_bootstd
__u_boot_list_2_uclass_driver_2_efi
0x000b28e4 0x48 lib/efi_driver/efi_uclass.o
0x000b28e4 _u_boot_list_2_uclass_driver_2_efi
__u_boot_list_2_uclass_driver_2_ethernet
0x000b292c 0x48 net/eth-uclass.o
0x000b292c _u_boot_list_2_uclass_driver_2_ethernet2.2 uclass实现
struct uclass {
void *priv_;
struct uclass_driver *uc_drv;
struct list_head dev_head;
struct list_head sibling_node;
};
#define ll_entry_start(_type, _list) \
({ \
static char start[0] __aligned(CONFIG_LINKER_LIST_ALIGN) \
__attribute__((unused)) \
__section("__u_boot_list_2_"#_list"_1"); \
_type * tmp = (_type *)&start; \
asm("":"+r"(tmp)); \
tmp; \
})
struct uclass_driver *lists_uclass_lookup(enum uclass_id id)
{
struct uclass_driver *uclass =
ll_entry_start(struct uclass_driver, uclass_driver);
const int n_ents = ll_entry_count(struct uclass_driver, uclass_driver);
struct uclass_driver *entry;
for (entry = uclass; entry != uclass + n_ents; entry++) {
if (entry->id == id)
return entry;
}
return NULL;
}3 uclass的使用
udevice的数据结构
struct udevice {
const struct driver *driver;
const char *name;
void *plat_;
void *parent_plat_;
void *uclass_plat_;
ulong driver_data;
struct udevice *parent;
void *priv_;
struct uclass *uclass;
void *uclass_priv_;
void *parent_priv_;
struct list_head uclass_node;
struct list_head child_head;
struct list_head sibling_node;
};调用函数获取udevices设备
int uclass_get_device_by_name(enum uclass_id id, const char *name, struct udevice **devp);
// 参考下面的例子
// 获取一个gpio@18100的gpio设备
uclass_get_device_by_name(UCLASS_GPIO, "gpio@18100", &gpio_dev1)
uclass_get_device_by_name(UCLASS_GPIO, "gpio@18140", &gpio_dev2);// 获取udevices的私有数据
void *dev_get_uclass_priv(const struct udevice *dev);对获取的私有数据进行操作
4 定义driver
U_BOOT_DRIVER(serial_stm32) = {
.name = "serial_stm32",
.id = UCLASS_SERIAL,
.of_match = of_match_ptr(stm32_serial_id),
.of_to_plat = of_match_ptr(stm32_serial_of_to_plat),
.plat_auto = sizeof(struct stm32x7_serial_plat),
.ops = &stm32_serial_ops,
.probe = stm32_serial_probe,
#if !CONFIG_IS_ENABLED(OF_CONTROL)
.flags = DM_FLAG_PRE_RELOC,
#endif
};
struct driver {
char *name;
enum uclass_id id;
const struct udevice_id *of_match;
int (*bind)(struct udevice *dev);
int (*probe)(struct udevice *dev);
int (*remove)(struct udevice *dev);
int (*unbind)(struct udevice *dev);
int (*of_to_plat)(struct udevice *dev);
int (*child_post_bind)(struct udevice *dev);
int (*child_pre_probe)(struct udevice *dev);
int (*child_post_remove)(struct udevice *dev);
int priv_auto;
int plat_auto;
int per_child_auto;
int per_child_plat_auto;
const void *ops; /* driver-specific operations */
uint32_t flags;
#if CONFIG_IS_ENABLED(ACPIGEN)
struct acpi_ops *acpi_ops;
#endif
};
#define U_BOOT_DRIVER(__name) \
ll_entry_declare(struct driver, __name, driver)
#define ll_entry_declare(_type, _name, _list) \
_type _u_boot_list_2_##_list##_2_##_name __aligned(4) \
__attribute__((unused)) \
__section("__u_boot_list_2_"#_list"_2_"#_name)