linux-kernel - [tip:x86/timers] x86/hpet: Separate counter check out of clocksource register code

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Date:   Thu, 27 Jun 2019 16:41:07 -0700
From:   tip-bot for Thomas Gleixner <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     ricardo.neri-calderon@...ux.intel.com, tglx@...utronix.de,
        linux-kernel@...r.kernel.org, Suravee.Suthikulpanit@....com,
        hpa@...or.com, andi.kleen@...el.com, peterz@...radead.org,
        eranian@...gle.com, ravi.v.shankar@...el.com, mingo@...nel.org,
        ashok.raj@...el.com
Subject: [tip:x86/timers] x86/hpet: Separate counter check out of
 clocksource register code

Commit-ID:  3222daf970f30133cc4c639cbecdc29c4ae91b2b
Gitweb:     https://git.kernel.org/tip/3222daf970f30133cc4c639cbecdc29c4ae91b2b
Author:     Thomas Gleixner <tglx@...utronix.de>
AuthorDate: Sun, 23 Jun 2019 15:23:51 +0200
Committer:  Thomas Gleixner <tglx@...utronix.de>
CommitDate: Fri, 28 Jun 2019 00:57:18 +0200

x86/hpet: Separate counter check out of clocksource register code

The init code checks whether the HPET counter works late in the init
function when the clocksource is registered. That should happen right with
the other sanity checks.

Split it into a separate validation function and move it to the other
sanity checks.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Reviewed-by: Ingo Molnar <mingo@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Ricardo Neri <ricardo.neri-calderon@...ux.intel.com>
Cc: Ashok Raj <ashok.raj@...el.com>
Cc: Andi Kleen <andi.kleen@...el.com>
Cc: Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>
Cc: Stephane Eranian <eranian@...gle.com>
Cc: Ravi Shankar <ravi.v.shankar@...el.com>
Link: https://lkml.kernel.org/r/20190623132435.058540608@linutronix.de

---
 arch/x86/kernel/hpet.c | 65 ++++++++++++++++++++++++--------------------------
 1 file changed, 31 insertions(+), 34 deletions(-)

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 71533f53fa1d..8c57dbf15e3b 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -809,38 +809,6 @@ static struct clocksource clocksource_hpet = {
 	.resume		= hpet_resume_counter,
 };
 
-static int __init hpet_clocksource_register(void)
-{
-	u64 start, now;
-	u64 t1;
-
-	/* Start the counter */
-	hpet_restart_counter();
-
-	/* Verify whether hpet counter works */
-	t1 = hpet_readl(HPET_COUNTER);
-	start = rdtsc();
-
-	/*
-	 * We don't know the TSC frequency yet, but waiting for
-	 * 200000 TSC cycles is safe:
-	 * 4 GHz == 50us
-	 * 1 GHz == 200us
-	 */
-	do {
-		rep_nop();
-		now = rdtsc();
-	} while ((now - start) < 200000UL);
-
-	if (t1 == hpet_readl(HPET_COUNTER)) {
-		pr_warn("Counter not counting. HPET disabled\n");
-		return -ENODEV;
-	}
-
-	clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq);
-	return 0;
-}
-
 /*
  * AMD SB700 based systems with spread spectrum enabled use a SMM based
  * HPET emulation to provide proper frequency setting.
@@ -869,6 +837,32 @@ static bool __init hpet_cfg_working(void)
 	return false;
 }
 
+static bool __init hpet_counting(void)
+{
+	u64 start, now, t1;
+
+	hpet_restart_counter();
+
+	t1 = hpet_readl(HPET_COUNTER);
+	start = rdtsc();
+
+	/*
+	 * We don't know the TSC frequency yet, but waiting for
+	 * 200000 TSC cycles is safe:
+	 * 4 GHz == 50us
+	 * 1 GHz == 200us
+	 */
+	do {
+		rep_nop();
+		now = rdtsc();
+	} while ((now - start) < 200000UL);
+
+	if (t1 == hpet_readl(HPET_COUNTER)) {
+		pr_warn("Counter not counting. HPET disabled\n");
+		return false;
+	}
+	return true;
+}
 
 /**
  * hpet_enable - Try to setup the HPET timer. Returns 1 on success.
@@ -890,6 +884,10 @@ int __init hpet_enable(void)
 	if (!hpet_cfg_working())
 		goto out_nohpet;
 
+	/* Validate that the counter is counting */
+	if (!hpet_counting())
+		goto out_nohpet;
+
 	/*
 	 * Read the period and check for a sane value:
 	 */
@@ -948,8 +946,7 @@ int __init hpet_enable(void)
 	}
 	hpet_print_config();
 
-	if (hpet_clocksource_register())
-		goto out_nohpet;
+	clocksource_register_hz(&clocksource_hpet, (u32)hpet_freq);
 
 	if (id & HPET_ID_LEGSUP) {
 		hpet_legacy_clockevent_register();