From: Yasir-Khan <yasir_khan@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Michal Simek <michal.simek@xxxxxxxxxx>
---
drivers/tty/serial/xilinx_uartps.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index dd4c02fa4820..ad77d0ed0c46 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -93,6 +93,7 @@
#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
--
1.9.1
--
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