Enum Channel

#[repr(u8)]
enum Channel {
    Channel0 = 0,
    Channel1 = 1,
    Channel2 = 2,
    ReadBackCommand = 3,
}

Used to select the configured channel in the MODE_COMMAND_PORT of the PIT.

Variants

Channel0 = 0

Channel 0. For more details, check CHANNEL0_PORT static variable

Channel1 = 1

Channel 1. For more details, check CHANNEL1_PORT static variable

Channel2 = 2

Channel 2. For more details, check CHANNEL2_PORT static variable

ReadBackCommand = 3

The read back command is a special command sent to the mode/command register. The register uses the following format if set to read back command:

Bits         Usage
7 and 6      Must be set for the read back command
5            Latch count flag (0 = latch count, 1 = don't latch count)
4            Latch status flag (0 = latch status, 1 = don't latch status)
3            Read back timer channel 2 (1 = yes, 0 = no)
2            Read back timer channel 1 (1 = yes, 0 = no)
1            Read back timer channel 0 (1 = yes, 0 = no)
0            Reserved

Bits 1 to 3 of the read back command select which PIT channels are affected, and allow multiple channels to be selected at the same time.

If bit 5 is clear, then any/all PIT channels selected with bits 1 to 3 will have their current count copied into their latch register.

If bit 4 is clear, then for any/all PIT channels selected with bits 1 to 3, the next read of the corresponding data port will return a status byte.

Ref: https://wiki.osdev.org/Programmable_Interval_Timer#Read_Back_Command.