linux-kernel - [tip: timers/core] clocksource/drivers/arm_global_timer: Simplify prescaler register access

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Message-ID: <171075645458.12214.3233394183212196975.tip-bot2@tip-bot2>
Date: Mon, 18 Mar 2024 10:07:34 -0000
From: "tip-bot2 for Martin Blumenstingl" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
 Daniel Lezcano <daniel.lezcano@...aro.org>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: timers/core] clocksource/drivers/arm_global_timer: Simplify
 prescaler register access

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     755350bcfb4ac8cbbb62bd7ee6be8271d4b2a88a
Gitweb:        https://git.kernel.org/tip/755350bcfb4ac8cbbb62bd7ee6be8271d4b2a88a
Author:        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
AuthorDate:    Sun, 25 Feb 2024 16:13:36 +01:00
Committer:     Daniel Lezcano <daniel.lezcano@...aro.org>
CommitterDate: Mon, 26 Feb 2024 10:07:25 +01:00

clocksource/drivers/arm_global_timer: Simplify prescaler register access

Use GENMASK() to define the prescaler mask and make the whole driver use
the mask (together with helpers such as FIELD_{GET,PREP,FIT}) instead of
needing an additional shift and max value constant.

Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
Link: https://lore.kernel.org/r/20240225151336.2728533-4-martin.blumenstingl@googlemail.com
---
 drivers/clocksource/arm_global_timer.c | 19 ++++++++-----------
 1 file changed, 8 insertions(+), 11 deletions(-)

diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c
index 4726a15..ab1c8c2 100644
--- a/drivers/clocksource/arm_global_timer.c
+++ b/drivers/clocksource/arm_global_timer.c
@@ -9,6 +9,7 @@
 
 #include <linux/init.h>
 #include <linux/interrupt.h>
+#include <linux/bitfield.h>
 #include <linux/clocksource.h>
 #include <linux/clockchips.h>
 #include <linux/cpu.h>
@@ -31,10 +32,7 @@
 #define GT_CONTROL_COMP_ENABLE		BIT(1)	/* banked */
 #define GT_CONTROL_IRQ_ENABLE		BIT(2)	/* banked */
 #define GT_CONTROL_AUTO_INC		BIT(3)	/* banked */
-#define GT_CONTROL_PRESCALER_SHIFT      8
-#define GT_CONTROL_PRESCALER_MAX        0xFF
-#define GT_CONTROL_PRESCALER_MASK       (GT_CONTROL_PRESCALER_MAX << \
-					 GT_CONTROL_PRESCALER_SHIFT)
+#define GT_CONTROL_PRESCALER_MASK	GENMASK(15, 8)
 
 #define GT_INT_STATUS	0x0c
 #define GT_INT_STATUS_EVENT_FLAG	BIT(0)
@@ -248,7 +246,7 @@ static void gt_write_presc(u32 psv)
 
 	reg = readl(gt_base + GT_CONTROL);
 	reg &= ~GT_CONTROL_PRESCALER_MASK;
-	reg |= psv << GT_CONTROL_PRESCALER_SHIFT;
+	reg |= FIELD_PREP(GT_CONTROL_PRESCALER_MASK, psv);
 	writel(reg, gt_base + GT_CONTROL);
 }
 
@@ -257,8 +255,7 @@ static u32 gt_read_presc(void)
 	u32 reg;
 
 	reg = readl(gt_base + GT_CONTROL);
-	reg &= GT_CONTROL_PRESCALER_MASK;
-	return reg >> GT_CONTROL_PRESCALER_SHIFT;
+	return FIELD_GET(GT_CONTROL_PRESCALER_MASK, reg);
 }
 
 static void __init gt_delay_timer_init(void)
@@ -273,9 +270,9 @@ static int __init gt_clocksource_init(void)
 	writel(0, gt_base + GT_COUNTER0);
 	writel(0, gt_base + GT_COUNTER1);
 	/* set prescaler and enable timer on all the cores */
-	writel(((CONFIG_ARM_GT_INITIAL_PRESCALER_VAL - 1) <<
-		GT_CONTROL_PRESCALER_SHIFT)
-	       | GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
+	writel(FIELD_PREP(GT_CONTROL_PRESCALER_MASK,
+			  CONFIG_ARM_GT_INITIAL_PRESCALER_VAL - 1) |
+	       GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
 
 #ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
 	sched_clock_register(gt_sched_clock_read, 64, gt_target_rate);
@@ -301,7 +298,7 @@ static int gt_clk_rate_change_cb(struct notifier_block *nb,
 		psv--;
 
 		/* prescaler within legal range? */
-		if (psv > GT_CONTROL_PRESCALER_MAX)
+		if (!FIELD_FIT(GT_CONTROL_PRESCALER_MASK, psv))
 			return NOTIFY_BAD;
 
 		/*