hm2_uart_setup
NAME
hm2_uart_setup — setup a Hostmot2 UART
SYNTAX
int hm2_uart_setup ( char *name, int bitrate, s32 tx_mode, s32 rx_mode )
DESCRIPTION
hm2_uart_setup Setup the bitrate for the UART named "name".
"name" is a unique string given to each UART during hostmot2
setup.
The names of the available UARTs are printed to standard output during
the driver loading process and take the form:
hm2_<board name>.<board index>.uart.<index>
For example
hm2_5i23.0.uart.0
The minimum bitrate is approximately 50bps, and the maximimum around the FPGA
frequency, 48MHz for a 5i23.
The UART function allows different RX and TX bitrates, but that is not currently
supported by this driver
tx_mode is bit mask defined in the Hostmot2 regmap:
Bit 0..3 = TXEnable delay. TXEnable delay specifies the transmit data holdoff time from the TXenable signal valid state. This is used for RS-485 (half duplex) operaton, to delay transmit data until the driver is enabled, allowing for driver enable delays, isolation barrier delays etc. Delay is in units of ClockLow period. Bit 4 = FIFOError, it indicates that a host push has overflowed the FIFO (Mainly for driver debugging) Bit 5 = DriveEnableAuto, When set, enables Drive when any data is in FIFO or Xmit Shift register,removes drive when FIFO and Xmit shift register are empty. Bit 6 = DriveEnableBit, If DriveEnableAuto is 0, controls Drive ( for software control of Xmit drive)
tx_mode is bit mask defined in the Hostmot2 regmap:
Bit 0 = FalseStart bit Status, 1 = false start bit detected Bit 1 = OverRun Status, 1 = overrun condition detected (no valid stop bit) Bit 2 = RXMaskEnable, 1= enable RXMask for half duplex operation, 0 = ignore RXMask Bit 4 = FIFOError, indicates that a host read has attemped to read more data than available. (mainly for driver debugging) Bit 5 = LostDataError, indicates that data was received with no room in FIFO, therefore lost Bit 6 = RXMask, RO RXMASK status Bit 7 = FIFO Has Data
"rx_mode" and "tx_mode" registers are currently write-only. There should possibly be a get-status function.
To write only to the tx_mode DriveEnable bit call this function with the bitrate
unchanged and -1 as the rx_mode
To change bitrate without altering mode settings send -1 to both modes.
RETURN VALUE
Returns 0 on success and -1 on failure
LICENCE
Issued under the terms of the GPL v2 License or any later version
AUTHOR
Andy Pugh
SEE ALSO
hm2_uart_send
hm2_uart_read
See mesa_uart.comp for an example usage