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serial: xuartps: Enable uart loopback mode

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This patch adds xilinx uart loopback support by modifying the
cdns_uart_set_mctrl function to handle the switch to loopback mode.
After this patch, the loopback mode can be enabled/disabled by
setting/clearing the TIOCM_LOOP modem bit via TIOCMBIS/TIOCMBIC
ioctls respectively.

Signed-off-by: Yasir-Khan <yasir_khan@mentor.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Yasir-Khan 2017-01-23 13:26:08 +01:00 committed by Greg Kroah-Hartman
parent aa75941ca1
commit 5935a2b3a5
1 changed files with 9 additions and 0 deletions
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9
drivers/tty/serial/xilinx_uartps.c
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@ -93,6 +93,7 @@ MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");
#define CDNS_UART_MR_CLKSEL 0x00000001 /* Pre-scalar selection */
#define CDNS_UART_MR_CHMODE_L_LOOP 0x00000200 /* Local loop back mode */
#define CDNS_UART_MR_CHMODE_NORM 0x00000000 /* Normal mode */
#define CDNS_UART_MR_CHMODE_MASK 0x00000300 /* Mask for mode bits */
#define CDNS_UART_MR_STOPMODE_2_BIT 0x00000080 /* 2 stop bits */
#define CDNS_UART_MR_STOPMODE_1_BIT 0x00000000 /* 1 stop bit */
@ -998,17 +999,25 @@ static unsigned int cdns_uart_get_mctrl(struct uart_port *port)
static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
u32 val;
u32 mode_reg;
val = readl(port->membase + CDNS_UART_MODEMCR);
mode_reg = readl(port->membase + CDNS_UART_MR);
val &= ~(CDNS_UART_MODEMCR_RTS | CDNS_UART_MODEMCR_DTR);
mode_reg &= ~CDNS_UART_MR_CHMODE_MASK;
if (mctrl & TIOCM_RTS)
val |= CDNS_UART_MODEMCR_RTS;
if (mctrl & TIOCM_DTR)
val |= CDNS_UART_MODEMCR_DTR;
if (mctrl & TIOCM_LOOP)
mode_reg |= CDNS_UART_MR_CHMODE_L_LOOP;
else
mode_reg |= CDNS_UART_MR_CHMODE_NORM;
writel(val, port->membase + CDNS_UART_MODEMCR);
writel(mode_reg, port->membase + CDNS_UART_MR);
}
#ifdef CONFIG_CONSOLE_POLL