The main purpose of a driver is to handle and manage devices, and most of the time expose their functionalities to the user space. The objective here is to gather the device's configuration parameters, and especially resources (memory region, interrupt line, DMA channel, clocks, and so on).
The following is the device node with which we will work during this section. It is the i.MX6 UART device's node, defined in arch/arm/boot/dts/imx6qdl.dtsi:
uart1: serial@02020000 {
compatible = "fsl,imx6q-uart", "fsl,imx21-uart";
reg = <0x02020000 0x4000>;
interrupts = <0 26 IRQ_TYPE_LEVEL_HIGH>;
clocks = <&clks IMX6QDL_CLK_UART_IPG>,
<&clks IMX6QDL_CLK_UART_SERIAL>;
clock-names = "ipg", "per";
dmas = <&sdma 25 4 0>, <&sdma 26 4 0>...