altera_uart: Add support for polling mode (IRQ-less)

Some Altera UART implementations doesn't route the IRQ line, so we have
to work in polling mode.

Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
Acked-by: Tobias Klauser <tklauser@distanz.ch>
Cc: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 22 insertions, 1 deletions

diff --git a/drivers/serial/altera_uart.c b/drivers/serial/altera_uart.c
index f8d8a00554da..7dd58da0ddf5 100644
--- a/drivers/serial/altera_uart.c
+++ b/drivers/serial/altera_uart.c
@@ -15,6 +15,7 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/timer.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/console.h>
@@ -76,6 +77,7 @@
  */
 struct altera_uart {
         struct uart_port port;
+        struct timer_list tmr;
         unsigned int sigs;      /* Local copy of line sigs */
         unsigned short imr;     /* Local IMR mirror */
 };
@@ -168,6 +170,7 @@ static void altera_uart_set_termios(struct uart_port *port,
         tty_termios_encode_baud_rate(termios, baud, baud);
 
         spin_lock_irqsave(&port->lock, flags);
+        uart_update_timeout(port, termios->c_cflag, baud);
         writel(baudclk, port->membase + ALTERA_UART_DIVISOR_REG);
         spin_unlock_irqrestore(&port->lock, flags);
 }
@@ -268,6 +271,15 @@ static irqreturn_t altera_uart_interrupt(int irq, void *data)
         return IRQ_RETVAL(isr);
 }
 
+static void altera_uart_timer(unsigned long data)
+{
+        struct uart_port *port = (void *)data;
+        struct altera_uart *pp = container_of(port, struct altera_uart, port);
+
+        altera_uart_interrupt(0, port);
+        mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
+}
+
 static void altera_uart_config_port(struct uart_port *port, int flags)
 {
         port->type = PORT_ALTERA_UART;
@@ -284,6 +296,12 @@ static int altera_uart_startup(struct uart_port *port)
         unsigned long flags;
         int ret;
 
+        if (!port->irq) {
+                setup_timer(&pp->tmr, altera_uart_timer, (unsigned long)port);
+                mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
+                return 0;
+        }
+
         ret = request_irq(port->irq, altera_uart_interrupt, IRQF_DISABLED,
                         DRV_NAME, port);
         if (ret) {
@@ -316,7 +334,10 @@ static void altera_uart_shutdown(struct uart_port *port)
 
         spin_unlock_irqrestore(&port->lock, flags);
 
-        free_irq(port->irq, port);
+        if (port->irq)
+                free_irq(port->irq, port);
+        else
+                del_timer_sync(&pp->tmr);
 }
 
 static const char *altera_uart_type(struct uart_port *port)