serial: 8250: Separate legacy irq handling from core port operations

Prepare for 8250 split; decouple irq setup/teardown and handler from
core port operations.

Introduce setup_irq() and release_irq() 8250 driver methods; the 8250
core will use these methods to install and remove irq handling for
the given 8250 port.

Refactor irq chain linking/unlinking from 8250 core into
univ8250_setup_irq()/univ8250_release_irq() for the universal 8250 driver.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 68 insertions, 30 deletions

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 625f81c9b55e..06bb2ced2c94 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1890,6 +1890,48 @@ static void serial8250_backup_timeout(unsigned long data)
                 jiffies + uart_poll_timeout(&up->port) + HZ / 5);
 }
 
+static int univ8250_setup_irq(struct uart_8250_port *up)
+{
+        struct uart_port *port = &up->port;
+        int retval = 0;
+
+        /*
+         * The above check will only give an accurate result the first time
+         * the port is opened so this value needs to be preserved.
+         */
+        if (up->bugs & UART_BUG_THRE) {
+                pr_debug("ttyS%d - using backup timer\n", serial_index(port));
+
+                up->timer.function = serial8250_backup_timeout;
+                up->timer.data = (unsigned long)up;
+                mod_timer(&up->timer, jiffies +
+                          uart_poll_timeout(port) + HZ / 5);
+        }
+
+        /*
+         * If the "interrupt" for this port doesn't correspond with any
+         * hardware interrupt, we use a timer-based system.  The original
+         * driver used to do this with IRQ0.
+         */
+        if (!port->irq) {
+                up->timer.data = (unsigned long)up;
+                mod_timer(&up->timer, jiffies + uart_poll_timeout(port));
+        } else
+                retval = serial_link_irq_chain(up);
+
+        return retval;
+}
+
+static void univ8250_release_irq(struct uart_8250_port *up)
+{
+        struct uart_port *port = &up->port;
+
+        del_timer_sync(&up->timer);
+        up->timer.function = serial8250_timeout;
+        if (port->irq)
+                serial_unlink_irq_chain(up);
+}
+
 static unsigned int serial8250_tx_empty(struct uart_port *port)
 {
         struct uart_8250_port *up = up_to_u8250p(port);
@@ -2194,35 +2236,12 @@ int serial8250_do_startup(struct uart_port *port)
                 if ((!(iir1 & UART_IIR_NO_INT) && (iir & UART_IIR_NO_INT)) ||
                     up->port.flags & UPF_BUG_THRE) {
                         up->bugs |= UART_BUG_THRE;
-                        pr_debug("ttyS%d - using backup timer\n",
-                                 serial_index(port));
                 }
         }
 
-        /*
-         * The above check will only give an accurate result the first time
-         * the port is opened so this value needs to be preserved.
-         */
-        if (up->bugs & UART_BUG_THRE) {
-                up->timer.function = serial8250_backup_timeout;
-                up->timer.data = (unsigned long)up;
-                mod_timer(&up->timer, jiffies +
-                        uart_poll_timeout(port) + HZ / 5);
-        }
-
-        /*
-         * If the "interrupt" for this port doesn't correspond with any
-         * hardware interrupt, we use a timer-based system.  The original
-         * driver used to do this with IRQ0.
-         */
-        if (!port->irq) {
-                up->timer.data = (unsigned long)up;
-                mod_timer(&up->timer, jiffies + uart_poll_timeout(port));
-        } else {
-                retval = serial_link_irq_chain(up);
-                if (retval)
-                        goto out;
-        }
+        retval = up->ops->setup_irq(up);
+        if (retval)
+                goto out;
 
         /*
          * Now, initialize the UART
@@ -2380,10 +2399,7 @@ void serial8250_do_shutdown(struct uart_port *port)
         serial_port_in(port, UART_RX);
         serial8250_rpm_put(up);
 
-        del_timer_sync(&up->timer);
-        up->timer.function = serial8250_timeout;
-        if (port->irq)
-                serial_unlink_irq_chain(up);
+        up->ops->release_irq(up);
 }
 EXPORT_SYMBOL_GPL(serial8250_do_shutdown);
 
@@ -3083,6 +3099,11 @@ static struct uart_ops serial8250_pops = {
 #endif
 };
 
+static const struct uart_8250_ops univ8250_driver_ops = {
+        .setup_irq      = univ8250_setup_irq,
+        .release_irq    = univ8250_release_irq,
+};
+
 static struct uart_8250_port serial8250_ports[UART_NR];
 
 /**
@@ -3137,6 +3158,8 @@ static void __init serial8250_isa_init_ports(void)
                 up->timer.function = serial8250_timeout;
                 up->cur_iotype = 0xFF;
 
+                up->ops = &univ8250_driver_ops;
+
                 /*
                  * ALPHA_KLUDGE_MCR needs to be killed.
                  */
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index ca9f87beac63..50735a9ad598 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -60,6 +60,20 @@ enum {
 };
 
 struct uart_8250_dma;
+struct uart_8250_port;
+
+/**
+ * 8250 core driver operations
+ *
+ * @setup_irq()         Setup irq handling. The universal 8250 driver links this
+ *                      port to the irq chain. Other drivers may @request_irq().
+ * @release_irq()       Undo irq handling. The universal 8250 driver unlinks
+ *                      the port from the irq chain.
+ */
+struct uart_8250_ops {
+        int             (*setup_irq)(struct uart_8250_port *);
+        void            (*release_irq)(struct uart_8250_port *);
+};
 
 /*
  * This should be used by drivers which want to register
@@ -100,6 +114,7 @@ struct uart_8250_port {
         unsigned char           msr_saved_flags;
 
         struct uart_8250_dma    *dma;
+        const struct uart_8250_ops *ops;
 
         /* 8250 specific callbacks */
         int                     (*dl_read)(struct uart_8250_port *);