新增uart4

设备树修改：

....

main_uart1_pins_default: main-uart1-pins-default {

pinctrl-single,pins = <

AM62X_IOPAD(0x1ac, PIN_INPUT, 2) /* (E19) MCASP0_AFSR.UART1_RXD */

AM62X_IOPAD(0x1b0, PIN_OUTPUT, 2) /* (A20) MCASP0_ACLKR.UART1_TXD */

>;

};

main_uart4_pins_default: main-uart4-pins-default {

pinctrl-single,pins = <

AM62X_IOPAD(0x70, PIN_OUTPUT, 2) /* (T24) UART4_TXD */

AM62X_IOPAD(0x6c, PIN_INPUT, 2) /* (T22) UART4_RXD */

>;

};

main_uart5_pins_default: main-uart5-pins-default {

pinctrl-single,pins = <

AM62X_IOPAD(0x08, PIN_INPUT, 5) /* (J24) OSPI0_DQS.UART5_CTSn */

AM62X_IOPAD(0x04, PIN_OUTPUT, 5) /* (G25) OSPI0_LBCLKO.UART5_RTSn */

AM62X_IOPAD(0x34, PIN_INPUT, 5) /* (H21) OSPI0_CSn2.UART5_RXD */

AM62X_IOPAD(0x38, PIN_OUTPUT, 5) /* (E24) OSPI0_CSn3.UART5_TXD */

>;

};

.....

....

&main_uart3 {

status = "disabled";

};

&main_uart4 {

pinctrl-names = "default";

pinctrl-0 = <&main_uart4_pins_default>;

/* Main UART1 is used by TIFS firmware */

status = "okay";

};

&main_uart5 {

pinctrl-names = "default";

pinctrl-0 = <&main_uart5_pins_default>;

status = "okay";

};

.....

重新编译内核生成设备树，放到开发板的boot目录下，重启更新设备树。生成的设备节点是ttyS6。