serial: 8250_dw: Add support for IrDA SIR mode

Add a set_ldisc function to enable/disable IrDA SIR mode according to
the new line discipline, if IrDA SIR mode is supported by the hardware
configuration.

Signed-off-by: Ed Blake <ed.blake@imgtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
index 459d726f9d59..c89fafc972b6 100644
--- a/drivers/tty/serial/8250/8250_dw.c
+++ b/drivers/tty/serial/8250/8250_dw.c
@@ -53,6 +53,8 @@
 /* Helper for fifo size calculation */
 #define DW_UART_CPR_FIFO_SIZE(a)        (((a >> 16) & 0xff) * 16)
 
+/* DesignWare specific register fields */
+#define DW_UART_MCR_SIRE                BIT(6)
 
 struct dw8250_data {
         u8                      usr_reg;
@@ -254,6 +256,22 @@ out:
         serial8250_do_set_termios(p, termios, old);
 }
 
+static void dw8250_set_ldisc(struct uart_port *p, struct ktermios *termios)
+{
+        struct uart_8250_port *up = up_to_u8250p(p);
+        unsigned int mcr = p->serial_in(p, UART_MCR);
+
+        if (up->capabilities & UART_CAP_IRDA) {
+                if (termios->c_line == N_IRDA)
+                        mcr |= DW_UART_MCR_SIRE;
+                else
+                        mcr &= ~DW_UART_MCR_SIRE;
+
+                p->serial_out(p, UART_MCR, mcr);
+        }
+        serial8250_do_set_ldisc(p, termios);
+}
+
 /*
  * dw8250_fallback_dma_filter will prevent the UART from getting just any free
  * channel on platforms that have DMA engines, but don't have any channels
@@ -357,6 +375,9 @@ static void dw8250_setup_port(struct uart_port *p)
 
         if (reg & DW_UART_CPR_AFCE_MODE)
                 up->capabilities |= UART_CAP_AFE;
+
+        if (reg & DW_UART_CPR_SIR_MODE)
+                up->capabilities |= UART_CAP_IRDA;
 }
 
 static int dw8250_probe(struct platform_device *pdev)
@@ -392,6 +413,7 @@ static int dw8250_probe(struct platform_device *pdev)
         p->iotype       = UPIO_MEM;
         p->serial_in    = dw8250_serial_in;
         p->serial_out   = dw8250_serial_out;
+        p->set_ldisc    = dw8250_set_ldisc;
 
         p->membase = devm_ioremap(dev, regs->start, resource_size(regs));
         if (!p->membase)