mfd: twl4030 irq fixes

The TWL4030 IRQ handler has a bug which leads to spinlock lock-up. It is
calling the 'unmask' function in a process context. :The mask/unmask/ack
functions are only designed to be called from the IRQ handler code,
or the proper API interfaces found in linux/interrupt.h.

Also there is no need to have IRQ chaining mechanism. The right way to
handle this is to claim the parent interrupt as a standard interrupt
and arrange for handle_twl4030_pih to take care of the rest of the devices.

Mail thread on this issue can be found at:
http://marc.info/?l=linux-arm-kernel&m=124629940123396&w=2

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Tested-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/twl4030-irq.c

@@ -180,14 +180,9 @@ static struct completion irq_event;
 static int twl4030_irq_thread(void *data)
 {
 	long irq = (long)data;
-	struct irq_desc *desc = irq_to_desc(irq);
 	static unsigned i2c_errors;
 	static const unsigned max_i2c_errors = 100;
 
-	if (!desc) {
-		pr_err("twl4030: Invalid IRQ: %ld\n", irq);
-		return -EINVAL;
-	}
 
 	current->flags |= PF_NOFREEZE;
 
@@ -240,7 +235,7 @@ static int twl4030_irq_thread(void *data)
 		}
 		local_irq_enable();
 
-		desc->chip->unmask(irq);
+		enable_irq(irq);
 	}
 
 	return 0;
@@ -255,25 +250,13 @@ static int twl4030_irq_thread(void *data)
  * thread.  All we do here is acknowledge and mask the interrupt and wakeup
  * the kernel thread.
  */
-static void handle_twl4030_pih(unsigned int irq, struct irq_desc *desc)
+static irqreturn_t handle_twl4030_pih(int irq, void *devid)
 {
 	/* Acknowledge, clear *AND* mask the interrupt... */
-	desc->chip->ack(irq);
-	complete(&irq_event);
-}
-
-static struct task_struct *start_twl4030_irq_thread(long irq)
-{
-	struct task_struct *thread;
-
-	init_completion(&irq_event);
-	thread = kthread_run(twl4030_irq_thread, (void *)irq, "twl4030-irq");
-	if (!thread)
-		pr_err("twl4030: could not create irq %ld thread!\n", irq);
-
-	return thread;
+	disable_irq_nosync(irq);
+	complete(devid);
+	return IRQ_HANDLED;
 }
-
 /*----------------------------------------------------------------------*/
 
 /*
@@ -734,18 +717,28 @@ int twl_init_irq(int irq_num, unsigned irq_base, unsigned irq_end)
 	}
 
 	/* install an irq handler to demultiplex the TWL4030 interrupt */
-	task = start_twl4030_irq_thread(irq_num);
-	if (!task) {
-		pr_err("twl4030: irq thread FAIL\n");
-		status = -ESRCH;
-		goto fail;
-	}
 
-	set_irq_data(irq_num, task);
-	set_irq_chained_handler(irq_num, handle_twl4030_pih);
 
-	return status;
+	init_completion(&irq_event);
 
+	status = request_irq(irq_num, handle_twl4030_pih, IRQF_DISABLED,
+				"TWL4030-PIH", &irq_event);
+	if (status < 0) {
+		pr_err("twl4030: could not claim irq%d: %d\n", irq_num, status);
+		goto fail_rqirq;
+	}
+
+	task = kthread_run(twl4030_irq_thread, (void *)irq_num, "twl4030-irq");
+	if (IS_ERR(task)) {
+		pr_err("twl4030: could not create irq %d thread!\n", irq_num);
+		status = PTR_ERR(task);
+		goto fail_kthread;
+	}
+	return status;
+fail_kthread:
+	free_irq(irq_num, &irq_event);
+fail_rqirq:
+	/* clean up twl4030_sih_setup */
 fail:
 	for (i = irq_base; i < irq_end; i++)
 		set_irq_chip_and_handler(i, NULL, NULL);