linux-kernel - [PATCH 1/4] irqchip/gic-v3: Implement read polling with dedicated API

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Date: Thu, 18 Jan 2024 19:27:36 +0800
From: Dawei Li <dawei.li@...ngroup.cn>
To: tglx@...utronix.de,
	maz@...nel.org
Cc: sdonthineni@...dia.com,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	dawei.li@...ngroup.cn,
	set_pte_at@...look.com
Subject: [PATCH 1/4] irqchip/gic-v3: Implement read polling with dedicated API

Kernel provide read*_poll_* API family to support looping based polling
code pattern like below:
while (...)
{
	val = op(addr);
	condition = cond(val);
	if (condition)
		break;

	/* Maybe some timeout handling stuff */

	cpu_relax();
	udelay();
}

As such, use readl_relaxed_poll_timeout_atomic() to implement atomic
register polling logic in gic-v3.

Signed-off-by: Dawei Li <dawei.li@...ngroup.cn>
---
 drivers/irqchip/irq-gic-v3.c | 27 ++++++++-------------------
 1 file changed, 8 insertions(+), 19 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 98b0329b7154..b9d9375a3434 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -19,6 +19,7 @@
 #include <linux/percpu.h>
 #include <linux/refcount.h>
 #include <linux/slab.h>
+#include <linux/iopoll.h>
 
 #include <linux/irqchip.h>
 #include <linux/irqchip/arm-gic-common.h>
@@ -251,17 +252,11 @@ static inline void __iomem *gic_dist_base(struct irq_data *d)
 
 static void gic_do_wait_for_rwp(void __iomem *base, u32 bit)
 {
-	u32 count = 1000000;	/* 1s! */
+	u32 val;
 
-	while (readl_relaxed(base + GICD_CTLR) & bit) {
-		count--;
-		if (!count) {
-			pr_err_ratelimited("RWP timeout, gone fishing\n");
-			return;
-		}
-		cpu_relax();
-		udelay(1);
-	}
+	if (readl_relaxed_poll_timeout_atomic(base + GICD_CTLR,
+		val, !(val & bit), 1, 1000000) == -ETIMEDOUT)
+		pr_err_ratelimited("RWP timeout, gone fishing\n");
 }
 
 /* Wait for completion of a distributor change */
@@ -279,7 +274,6 @@ static void gic_redist_wait_for_rwp(void)
 static void gic_enable_redist(bool enable)
 {
 	void __iomem *rbase;
-	u32 count = 1000000;	/* 1s! */
 	u32 val;
 
 	if (gic_data.flags & FLAGS_WORKAROUND_GICR_WAKER_MSM8996)
@@ -301,14 +295,9 @@ static void gic_enable_redist(bool enable)
 			return;	/* No PM support in this redistributor */
 	}
 
-	while (--count) {
-		val = readl_relaxed(rbase + GICR_WAKER);
-		if (enable ^ (bool)(val & GICR_WAKER_ChildrenAsleep))
-			break;
-		cpu_relax();
-		udelay(1);
-	}
-	if (!count)
+	if (readl_relaxed_poll_timeout_atomic(rbase + GICR_WAKER,
+		val, enable ^ (bool)(val & GICR_WAKER_ChildrenAsleep),
+		1, 1000000) == -ETIMEDOUT)
 		pr_err_ratelimited("redistributor failed to %s...\n",
 				   enable ? "wakeup" : "sleep");
 }
-- 
2.27.0