bind command

Synopsis

bind <node path> <driver>
bind <class> <index> <driver>

Description

The bind command is used to bind a device to a driver. This makes the device available in U-Boot.

While binding to a node path typically provides a working device binding by parent node and driver may lead to a device that is only partially initialized.

node path

path of the device’s device-tree node

class

device class name

index

index of the parent device in the device class

driver

device driver name

Example

Given a system with a real time clock device with device path /pl031@9010000 and using driver rtc-pl031 unbinding and binding of the device is demonstrated using the two alternative bind syntaxes.

=> dm tree
 Class     Index  Probed  Driver                Name
-----------------------------------------------------------
 root          0  [ + ]   root_driver           root_driver
...
 rtc           0  [   ]   rtc-pl031             |-- pl031@9010000
...
=> fdt addr $fdtcontroladdr
Working FDT set to 7ed7fdb0
=> fdt print
/ {
        interrupt-parent = <0x00008003>;
        model = "linux,dummy-virt";
        #size-cells = <0x00000002>;
        #address-cells = <0x00000002>;
        compatible = "linux,dummy-virt";
...
        pl031@9010000 {
                clock-names = "apb_pclk";
                clocks = <0x00008000>;
                interrupts = <0x00000000 0x00000002 0x00000004>;
                reg = <0x00000000 0x09010000 0x00000000 0x00001000>;
                compatible = "arm,pl031", "arm,primecell";
        };
...
}
=> unbind /pl031@9010000
=> date
Cannot find RTC: err=-19
=> dm tree
 Class     Index  Probed  Driver                Name
-----------------------------------------------------------
 root          0  [ + ]   root_driver           root_driver
...
=> bind /pl031@9010000 rtc-pl031
=> dm tree
 Class     Index  Probed  Driver                Name
-----------------------------------------------------------
 root          0  [ + ]   root_driver           root_driver
...
 rtc           0  [   ]   rtc-pl031             |-- pl031@9010000
=> date
Date: 2023-06-22 (Thursday)    Time: 15:14:51
=> unbind rtc 0 rtc-pl031
=> bind root 0 rtc-pl031
=> date
Date: 1980-08-19 (Tuesday)    Time: 14:45:30

Obviously the device is not initialized correctly by the last bind command.

Configuration

The bind command is only available if CONFIG_CMD_BIND=y.

Return code

The return code $? is 0 (true) on success and 1 (false) on failure.