clk: at91: remove IRQ handling and use polling

The AT91 clock drivers make use of IRQs to avoid polling when waiting for
some clocks to be enabled. Unfortunately, this leads to a crash when those
IRQs are threaded (which happens when using preempt-rt) because they are
registered before thread creation is possible.

Use polling on those clocks instead to avoid the problem.

Acked-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

1 files changed, 4 insertions, 42 deletions

diff --git a/drivers/clk/at91/clk-master.c b/drivers/clk/at91/clk-master.c
index 8d94ddfc9c72..7d4a1864ea7c 100644
--- a/drivers/clk/at91/clk-master.c
+++ b/drivers/clk/at91/clk-master.c
@@ -12,13 +12,6 @@
 #include <linux/clkdev.h>
 #include <linux/clk/at91_pmc.h>
 #include <linux/of.h>
-#include <linux/of_address.h>
-#include <linux/of_irq.h>
-#include <linux/io.h>
-#include <linux/wait.h>
-#include <linux/sched.h>
-#include <linux/interrupt.h>
-#include <linux/irq.h>
 #include <linux/mfd/syscon.h>
 #include <linux/regmap.h>
 
@@ -47,22 +40,10 @@ struct clk_master_layout {
 struct clk_master {
 	struct clk_hw hw;
 	struct regmap *regmap;
-	unsigned int irq;
-	wait_queue_head_t wait;
 	const struct clk_master_layout *layout;
 	const struct clk_master_characteristics *characteristics;
 };
 
-static irqreturn_t clk_master_irq_handler(int irq, void *dev_id)
-{
-	struct clk_master *master = (struct clk_master *)dev_id;
-
-	wake_up(&master->wait);
-	disable_irq_nosync(master->irq);
-
-	return IRQ_HANDLED;
-}
-
 static inline bool clk_master_ready(struct regmap *regmap)
 {
 	unsigned int status;
@@ -76,11 +57,8 @@ static int clk_master_prepare(struct clk_hw *hw)
 {
 	struct clk_master *master = to_clk_master(hw);
 
-	while (!clk_master_ready(master->regmap)) {
-		enable_irq(master->irq);
-		wait_event(master->wait,
-			   clk_master_ready(master->regmap));
-	}
+	while (!clk_master_ready(master->regmap))
+		cpu_relax();
 
 	return 0;
 }
@@ -143,13 +121,12 @@ static const struct clk_ops master_ops = {
 };
 
 static struct clk * __init
-at91_clk_register_master(struct regmap *regmap, unsigned int irq,
+at91_clk_register_master(struct regmap *regmap,
 		const char *name, int num_parents,
 		const char **parent_names,
 		const struct clk_master_layout *layout,
 		const struct clk_master_characteristics *characteristics)
 {
-	int ret;
 	struct clk_master *master;
 	struct clk *clk = NULL;
 	struct clk_init_data init;
@@ -171,19 +148,9 @@ at91_clk_register_master(struct regmap *regmap, unsigned int irq,
 	master->layout = layout;
 	master->characteristics = characteristics;
 	master->regmap = regmap;
-	master->irq = irq;
-	init_waitqueue_head(&master->wait);
-	irq_set_status_flags(master->irq, IRQ_NOAUTOEN);
-	ret = request_irq(master->irq, clk_master_irq_handler,
-			  IRQF_TRIGGER_HIGH, "clk-master", master);
-	if (ret) {
-		kfree(master);
-		return ERR_PTR(ret);
-	}
 
 	clk = clk_register(NULL, &master->hw);
 	if (IS_ERR(clk)) {
-		free_irq(master->irq, master);
 		kfree(master);
 	}
 
@@ -233,7 +200,6 @@ of_at91_clk_master_setup(struct device_node *np,
 {
 	struct clk *clk;
 	int num_parents;
-	unsigned int irq;
 	const char *parent_names[MASTER_SOURCE_MAX];
 	const char *name = np->name;
 	struct clk_master_characteristics *characteristics;
@@ -255,11 +221,7 @@ of_at91_clk_master_setup(struct device_node *np,
 	if (IS_ERR(regmap))
 		return;
 
-	irq = irq_of_parse_and_map(np, 0);
-	if (!irq)
-		goto out_free_characteristics;
-
-	clk = at91_clk_register_master(regmap, irq, name, num_parents,
+	clk = at91_clk_register_master(regmap, name, num_parents,
 				       parent_names, layout,
 				       characteristics);
 	if (IS_ERR(clk))