From: "tip-bot2 for Tony Lindgren" <tip-bot2@linutronix.de>
To: linux-tip-commits@vger.kernel.org
Cc: Keerthy <j-keerthy@ti.com>, Tero Kristo <kristo@kernel.org>,
Tony Lindgren <tony@atomide.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: [tip: timers/core] clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940
Date: Fri, 09 Apr 2021 10:27:24 -0000 [thread overview]
Message-ID: <161796404495.29796.7785407556294992309.tip-bot2@tip-bot2> (raw)
In-Reply-To: <20210323074326.28302-3-tony@atomide.com>
The following commit has been merged into the timers/core branch of tip:
Commit-ID: 25de4ce5ed02994aea8bc111d133308f6fd62566
Gitweb: https://git.kernel.org/tip/25de4ce5ed02994aea8bc111d133308f6fd62566
Author: Tony Lindgren <tony@atomide.com>
AuthorDate: Tue, 23 Mar 2021 09:43:26 +02:00
Committer: Daniel Lezcano <daniel.lezcano@linaro.org>
CommitterDate: Thu, 08 Apr 2021 16:41:18 +02:00
clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940
There is a timer wrap issue on dra7 for the ARM architected timer.
In a typical clock configuration the timer fails to wrap after 388 days.
To work around the issue, we need to use timer-ti-dm percpu timers instead.
Let's configure dmtimer3 and 4 as percpu timers by default, and warn about
the issue if the dtb is not configured properly.
Let's do this as a single patch so it can be backported to v5.8 and later
kernels easily. Note that this patch depends on earlier timer-ti-dm
systimer posted mode fixes, and a preparatory clockevent patch
"clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue".
For more information, please see the errata for "AM572x Sitara Processors
Silicon Revisions 1.1, 2.0":
https://www.ti.com/lit/er/sprz429m/sprz429m.pdf
The concept is based on earlier reference patches done by Tero Kristo and
Keerthy.
Cc: Keerthy <j-keerthy@ti.com>
Cc: Tero Kristo <kristo@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20210323074326.28302-3-tony@atomide.com
---
arch/arm/boot/dts/dra7-l4.dtsi | 4 +-
arch/arm/boot/dts/dra7.dtsi | 20 ++++++-
drivers/clocksource/timer-ti-dm-systimer.c | 76 +++++++++++++++++++++-
include/linux/cpuhotplug.h | 1 +-
4 files changed, 99 insertions(+), 2 deletions(-)
diff --git a/arch/arm/boot/dts/dra7-l4.dtsi b/arch/arm/boot/dts/dra7-l4.dtsi
index 3bf90d9..a294a02 100644
--- a/arch/arm/boot/dts/dra7-l4.dtsi
+++ b/arch/arm/boot/dts/dra7-l4.dtsi
@@ -1168,7 +1168,7 @@
};
};
- target-module@34000 { /* 0x48034000, ap 7 46.0 */
+ timer3_target: target-module@34000 { /* 0x48034000, ap 7 46.0 */
compatible = "ti,sysc-omap4-timer", "ti,sysc";
reg = <0x34000 0x4>,
<0x34010 0x4>;
@@ -1195,7 +1195,7 @@
};
};
- target-module@36000 { /* 0x48036000, ap 9 4e.0 */
+ timer4_target: target-module@36000 { /* 0x48036000, ap 9 4e.0 */
compatible = "ti,sysc-omap4-timer", "ti,sysc";
reg = <0x36000 0x4>,
<0x36010 0x4>;
diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi
index ce11947..53d6878 100644
--- a/arch/arm/boot/dts/dra7.dtsi
+++ b/arch/arm/boot/dts/dra7.dtsi
@@ -46,6 +46,7 @@
timer {
compatible = "arm,armv7-timer";
+ status = "disabled"; /* See ARM architected timer wrap erratum i940 */
interrupts = <GIC_PPI 13 (GIC_CPU_MASK_SIMPLE(2) | IRQ_TYPE_LEVEL_LOW)>,
<GIC_PPI 14 (GIC_CPU_MASK_SIMPLE(2) | IRQ_TYPE_LEVEL_LOW)>,
<GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(2) | IRQ_TYPE_LEVEL_LOW)>,
@@ -1241,3 +1242,22 @@
assigned-clock-parents = <&sys_32k_ck>;
};
};
+
+/* Local timers, see ARM architected timer wrap erratum i940 */
+&timer3_target {
+ ti,no-reset-on-init;
+ ti,no-idle;
+ timer@0 {
+ assigned-clocks = <&l4per_clkctrl DRA7_L4PER_TIMER3_CLKCTRL 24>;
+ assigned-clock-parents = <&timer_sys_clk_div>;
+ };
+};
+
+&timer4_target {
+ ti,no-reset-on-init;
+ ti,no-idle;
+ timer@0 {
+ assigned-clocks = <&l4per_clkctrl DRA7_L4PER_TIMER4_CLKCTRL 24>;
+ assigned-clock-parents = <&timer_sys_clk_div>;
+ };
+};
diff --git a/drivers/clocksource/timer-ti-dm-systimer.c b/drivers/clocksource/timer-ti-dm-systimer.c
index 3308031..b6f9796 100644
--- a/drivers/clocksource/timer-ti-dm-systimer.c
+++ b/drivers/clocksource/timer-ti-dm-systimer.c
@@ -2,6 +2,7 @@
#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
+#include <linux/cpuhotplug.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/iopoll.h>
@@ -630,6 +631,78 @@ err_out_free:
return error;
}
+/* Dmtimer as percpu timer. See dra7 ARM architected timer wrap erratum i940 */
+static DEFINE_PER_CPU(struct dmtimer_clockevent, dmtimer_percpu_timer);
+
+static int __init dmtimer_percpu_timer_init(struct device_node *np, int cpu)
+{
+ struct dmtimer_clockevent *clkevt;
+ int error;
+
+ if (!cpu_possible(cpu))
+ return -EINVAL;
+
+ if (!of_property_read_bool(np->parent, "ti,no-reset-on-init") ||
+ !of_property_read_bool(np->parent, "ti,no-idle"))
+ pr_warn("Incomplete dtb for percpu dmtimer %pOF\n", np->parent);
+
+ clkevt = per_cpu_ptr(&dmtimer_percpu_timer, cpu);
+
+ error = dmtimer_clkevt_init_common(clkevt, np, CLOCK_EVT_FEAT_ONESHOT,
+ cpumask_of(cpu), "percpu-dmtimer",
+ 500);
+ if (error)
+ return error;
+
+ return 0;
+}
+
+/* See TRM for timer internal resynch latency */
+static int omap_dmtimer_starting_cpu(unsigned int cpu)
+{
+ struct dmtimer_clockevent *clkevt = per_cpu_ptr(&dmtimer_percpu_timer, cpu);
+ struct clock_event_device *dev = &clkevt->dev;
+ struct dmtimer_systimer *t = &clkevt->t;
+
+ clockevents_config_and_register(dev, t->rate, 3, ULONG_MAX);
+ irq_force_affinity(dev->irq, cpumask_of(cpu));
+
+ return 0;
+}
+
+static int __init dmtimer_percpu_timer_startup(void)
+{
+ struct dmtimer_clockevent *clkevt = per_cpu_ptr(&dmtimer_percpu_timer, 0);
+ struct dmtimer_systimer *t = &clkevt->t;
+
+ if (t->sysc) {
+ cpuhp_setup_state(CPUHP_AP_TI_GP_TIMER_STARTING,
+ "clockevents/omap/gptimer:starting",
+ omap_dmtimer_starting_cpu, NULL);
+ }
+
+ return 0;
+}
+subsys_initcall(dmtimer_percpu_timer_startup);
+
+static int __init dmtimer_percpu_quirk_init(struct device_node *np, u32 pa)
+{
+ struct device_node *arm_timer;
+
+ arm_timer = of_find_compatible_node(NULL, NULL, "arm,armv7-timer");
+ if (of_device_is_available(arm_timer)) {
+ pr_warn_once("ARM architected timer wrap issue i940 detected\n");
+ return 0;
+ }
+
+ if (pa == 0x48034000) /* dra7 dmtimer3 */
+ return dmtimer_percpu_timer_init(np, 0);
+ else if (pa == 0x48036000) /* dra7 dmtimer4 */
+ return dmtimer_percpu_timer_init(np, 1);
+
+ return 0;
+}
+
/* Clocksource */
static struct dmtimer_clocksource *
to_dmtimer_clocksource(struct clocksource *cs)
@@ -763,6 +836,9 @@ static int __init dmtimer_systimer_init(struct device_node *np)
if (clockevent == pa)
return dmtimer_clockevent_init(np);
+ if (of_machine_is_compatible("ti,dra7"))
+ return dmtimer_percpu_quirk_init(np, pa);
+
return 0;
}
diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index f14adb8..cc7c3fd 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -135,6 +135,7 @@ enum cpuhp_state {
CPUHP_AP_RISCV_TIMER_STARTING,
CPUHP_AP_CLINT_TIMER_STARTING,
CPUHP_AP_CSKY_TIMER_STARTING,
+ CPUHP_AP_TI_GP_TIMER_STARTING,
CPUHP_AP_HYPERV_TIMER_STARTING,
CPUHP_AP_KVM_STARTING,
CPUHP_AP_KVM_ARM_VGIC_INIT_STARTING,
next prev parent reply other threads:[~2021-04-09 10:28 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 7:43 [PATCHv2 0/2] Fixes for for dra7 timer wrap errata i940 Tony Lindgren
2021-03-23 7:43 ` [PATCH 1/2] clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue Tony Lindgren
2021-04-09 10:27 ` [tip: timers/core] " tip-bot2 for Tony Lindgren
2021-03-23 7:43 ` [PATCH 2/2] clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940 Tony Lindgren
2021-04-09 10:27 ` tip-bot2 for Tony Lindgren [this message]
2022-01-29 21:05 ` Drew Fustini
2022-01-31 10:16 ` Tony Lindgren
2022-02-02 20:54 ` Drew Fustini
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