Input: split i8042 interrupt handling into an IRQ handler and a tasklet

drivers/input/serio/i8042.c

@@ -2,6 +2,7 @@
  *  i8042 keyboard and mouse controller driver for Linux
  *
  *  Copyright (c) 1999-2002 Vojtech Pavlik
+ *  Copyright (c) 2004      Dmitry Torokhov
  */
 
 /*
@@ -74,6 +75,14 @@ struct i8042_values {
 	unsigned char *phys;
 };
 
+#define I8042_QUEUE_LEN		64
+struct {
+	unsigned char str[I8042_QUEUE_LEN];
+	unsigned char data[I8042_QUEUE_LEN];
+	unsigned int read_pos;
+	unsigned int write_pos;
+} i8042_buf;
+
 static struct serio i8042_kbd_port;
 static struct serio i8042_aux_port;
 static unsigned char i8042_initial_ctr;
@@ -82,7 +91,7 @@ static unsigned char i8042_mux_open;
 static unsigned char i8042_mux_present;
 static unsigned char i8042_sysdev_initialized;
 static struct pm_dev *i8042_pm_dev;
-struct timer_list i8042_timer;
+static struct timer_list i8042_timer;
 
 /*
  * Shared IRQ's require a device pointer, but this driver doesn't support
@@ -374,31 +383,28 @@ static char i8042_mux_short[4][16];
 static char i8042_mux_phys[4][32];
 
 /*
- * i8042_interrupt() is the most important function in this driver -
- * it handles the interrupts from the i8042, and sends incoming bytes
- * to the upper layers.
+ * i8042_handle_data() is the most important function in this driver -
+ * it processes data received by i8042_interrupt and sends it to the
+ * upper layers.
  */
 
-static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+static void i8042_handle_data(unsigned long notused)
 {
-	unsigned long flags;
 	unsigned char str, data = 0;
 	unsigned int dfl;
-	int ret;
 
-	mod_timer(&i8042_timer, jiffies + I8042_POLL_PERIOD);
+	/*
+	 * No locking it required on i8042_buf as the tasklet is guaranteed
+	 * to be serialized and if write_pos changes while comparing it with
+	 * read_pos another run will be scheduled by i8042_interrupt.
+	 */
+	while (i8042_buf.read_pos != i8042_buf.write_pos) {
 
-	spin_lock_irqsave(&i8042_lock, flags);
-	str = i8042_read_status();
-	if (str & I8042_STR_OBF)
-		data = i8042_read_data();
-	spin_unlock_irqrestore(&i8042_lock, flags);
+		str = i8042_buf.str[i8042_buf.read_pos];
+		data = i8042_buf.data[i8042_buf.read_pos];
 
-	if (~str & I8042_STR_OBF) {
-		if (irq) dbg("Interrupt %d, without any data", irq);
-		ret = 0;
-		goto out;
-	}
+		i8042_buf.read_pos++;
+		i8042_buf.read_pos %= I8042_QUEUE_LEN;
 
 		dfl = ((str & I8042_STR_PARITY)  ? SERIO_PARITY  : 0) |
 	      	      ((str & I8042_STR_TIMEOUT) ? SERIO_TIMEOUT : 0);
@@ -419,32 +425,67 @@ static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs)
 				dfl & SERIO_PARITY ? ", bad parity" : "",
 				dfl & SERIO_TIMEOUT ? ", timeout" : "");
 
-		serio_interrupt(i8042_mux_port + ((str >> 6) & 3), data, dfl, regs);
-
-		goto irq_ret;
-	}
+			serio_interrupt(i8042_mux_port + ((str >> 6) & 3), data, dfl, NULL);
+		} else {
 
 			dbg("%02x <- i8042 (interrupt, %s, %d%s%s)",
 				data, (str & I8042_STR_AUXDATA) ? "aux" : "kbd", irq,
 				dfl & SERIO_PARITY ? ", bad parity" : "",
 				dfl & SERIO_TIMEOUT ? ", timeout" : "");
 
-	if (i8042_aux_values.exists && (str & I8042_STR_AUXDATA)) {
-		serio_interrupt(&i8042_aux_port, data, dfl, regs);
-		goto irq_ret;
+			if (i8042_aux_values.exists && (str & I8042_STR_AUXDATA))
+				serio_interrupt(&i8042_aux_port, data, dfl, NULL);
+			else if (i8042_kbd_values.exists)
+				serio_interrupt(&i8042_kbd_port, data, dfl, NULL);
 		}
+	}
+}
 
-	if (!i8042_kbd_values.exists)
-		goto irq_ret;
+DECLARE_TASKLET(i8042_tasklet, i8042_handle_data, 0);
 
-	serio_interrupt(&i8042_kbd_port, data, dfl, regs);
+/*
+ * i8042_interrupt() handles the interrupts from i8042 and schedules
+ * i8042_handle_data to process and pass received bytes to the upper
+ * layers.
+ */
 
-irq_ret:
-	ret = 1;
-out:
-	return IRQ_RETVAL(ret);
+static irqreturn_t i8042_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+	unsigned long flags;
+	unsigned char str;
+	unsigned int n_bytes = 0;
+
+	mod_timer(&i8042_timer, jiffies + I8042_POLL_PERIOD);
+
+	spin_lock_irqsave(&i8042_lock, flags);
+
+	while ((str = i8042_read_status()) & I8042_STR_OBF) {
+
+		n_bytes++;
+
+		i8042_buf.str[i8042_buf.write_pos] = str;
+		i8042_buf.data[i8042_buf.write_pos] = i8042_read_data();
+
+		i8042_buf.write_pos++;
+		i8042_buf.write_pos %= I8042_QUEUE_LEN;
+
+		if (unlikely(i8042_buf.write_pos == i8042_buf.read_pos))
+			printk(KERN_WARNING "i8042.c: ring buffer full\n");
+	}
+
+	spin_unlock_irqrestore(&i8042_lock, flags);
+
+	if (unlikely(n_bytes == 0)) {
+		if (irq) dbg("Interrupt %d, without any data", irq);
+		return IRQ_NONE;
+	}
+
+	tasklet_schedule(&i8042_tasklet);
+
+	return IRQ_HANDLED;
 }
 
+
 /*
  * i8042_enable_mux_mode checks whether the controller has an active
  * multiplexor and puts the chip into Multiplexed (as opposed to
@@ -1020,6 +1061,8 @@ void __exit i8042_exit(void)
 		if (i8042_mux_values[i].exists)
 			serio_unregister_port(i8042_mux_port + i);
 
+	tasklet_kill(&i8042_tasklet);
+
 	i8042_platform_exit();
 }