diff options
| -rw-r--r-- | drivers/tty/serial/8250/8250_exar.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c index a18fc8f01a41..6085d356ad86 100644 --- a/drivers/tty/serial/8250/8250_exar.c +++ b/drivers/tty/serial/8250/8250_exar.c @@ -77,6 +77,9 @@ #define UART_EXAR_RS485_DLY(x) ((x) << 4) +#define UART_EXAR_DLD 0x02 /* Divisor Fractional */ +#define UART_EXAR_DLD_485_POLARITY 0x80 /* RS-485 Enable Signal Polarity */ + /* * IOT2040 MPIO wiring semantics: * @@ -438,6 +441,44 @@ static int generic_rs485_config(struct uart_port *port, struct ktermios *termios return 0; } +static int sealevel_rs485_config(struct uart_port *port, struct ktermios *termios, + struct serial_rs485 *rs485) +{ + u8 __iomem *p = port->membase; + u8 old_lcr; + u8 efr; + u8 dld; + int ret; + + ret = generic_rs485_config(port, termios, rs485); + if (ret) + return ret; + + if (rs485->flags & SER_RS485_ENABLED) { + old_lcr = readb(p + UART_LCR); + + /* Set EFR[4]=1 to enable enhanced feature registers */ + efr = readb(p + UART_XR_EFR); + efr |= UART_EFR_ECB; + writeb(efr, p + UART_XR_EFR); + + /* Set MCR to use DTR as Auto-RS485 Enable signal */ + writeb(UART_MCR_OUT1, p + UART_MCR); + + /* Set LCR[7]=1 to enable access to DLD register */ + writeb(old_lcr | UART_LCR_DLAB, p + UART_LCR); + + /* Set DLD[7]=1 for inverted RS485 Enable logic */ + dld = readb(p + UART_EXAR_DLD); + dld |= UART_EXAR_DLD_485_POLARITY; + writeb(dld, p + UART_EXAR_DLD); + + writeb(old_lcr, p + UART_LCR); + } + + return 0; +} + static const struct serial_rs485 generic_rs485_supported = { .flags = SER_RS485_ENABLED, }; @@ -559,6 +600,9 @@ pci_xr17v35x_setup(struct exar8250 *priv, struct pci_dev *pcidev, port->port.rs485_config = platform->rs485_config; port->port.rs485_supported = *(platform->rs485_supported); + if (pcidev->subsystem_vendor == PCI_VENDOR_ID_SEALEVEL) + port->port.rs485_config = sealevel_rs485_config; + /* * Setup the UART clock for the devices on expansion slot to * half the clock speed of the main chip (which is 125MHz) |