[Backport for linux-5.10.y PATCH 1/2] clocksource/drivers/timer-ti-dm: Prepare to handle dra7 timer wrap issue
Upstream commit 3efe7a878a11c13b5297057bfc1e5639ce1241ce. Updated to apply to stable linux-5.10.y without need for upstream typo fix commit 4bf07f6562a01a488877e05267808da7147f44a5. Needed to avoid duplicate code for upstream commit 25de4ce5ed02994aea8bc111d133308f6fd62566.
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 timers instead.
Let's prepare for adding support for percpu timers by adding a common dmtimer_clkevt_init_common() and call it from dmtimer_clockevent_init(). This patch makes no intentional functional changes.
Signed-off-by: Tony Lindgren tony@atomide.com Signed-off-by: Daniel Lezcano daniel.lezcano@linaro.org Link: https://lore.kernel.org/r/20210323074326.28302-2-tony@atomide.com --- drivers/clocksource/timer-ti-dm-systimer.c | 68 ++++++++++++++-------- 1 file changed, 44 insertions(+), 24 deletions(-)
diff --git a/drivers/clocksource/timer-ti-dm-systimer.c b/drivers/clocksource/timer-ti-dm-systimer.c --- a/drivers/clocksource/timer-ti-dm-systimer.c +++ b/drivers/clocksource/timer-ti-dm-systimer.c @@ -530,17 +530,17 @@ static void omap_clockevent_unidle(struct clock_event_device *evt) writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->wakeup); }
-static int __init dmtimer_clockevent_init(struct device_node *np) +static int __init dmtimer_clkevt_init_common(struct dmtimer_clockevent *clkevt, + struct device_node *np, + unsigned int features, + const struct cpumask *cpumask, + const char *name, + int rating) { - struct dmtimer_clockevent *clkevt; struct clock_event_device *dev; struct dmtimer_systimer *t; int error;
- clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL); - if (!clkevt) - return -ENOMEM; - t = &clkevt->t; dev = &clkevt->dev;
@@ -548,25 +548,23 @@ static int __init dmtimer_clockevent_init(struct device_node *np) * We mostly use cpuidle_coupled with ARM local timers for runtime, * so there's probably no use for CLOCK_EVT_FEAT_DYNIRQ here. */ - dev->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT; - dev->rating = 300; + dev->features = features; + dev->rating = rating; dev->set_next_event = dmtimer_set_next_event; dev->set_state_shutdown = dmtimer_clockevent_shutdown; dev->set_state_periodic = dmtimer_set_periodic; dev->set_state_oneshot = dmtimer_clockevent_shutdown; dev->set_state_oneshot_stopped = dmtimer_clockevent_shutdown; dev->tick_resume = dmtimer_clockevent_shutdown; - dev->cpumask = cpu_possible_mask; + dev->cpumask = cpumask;
dev->irq = irq_of_parse_and_map(np, 0); - if (!dev->irq) { - error = -ENXIO; - goto err_out_free; - } + if (!dev->irq) + return -ENXIO;
error = dmtimer_systimer_setup(np, &clkevt->t); if (error) - goto err_out_free; + return error;
clkevt->period = 0xffffffff - DIV_ROUND_CLOSEST(t->rate, HZ);
@@ -578,32 +576,54 @@ static int __init dmtimer_clockevent_init(struct device_node *np) writel_relaxed(OMAP_TIMER_CTRL_POSTED, t->base + t->ifctrl);
error = request_irq(dev->irq, dmtimer_clockevent_interrupt, - IRQF_TIMER, "clockevent", clkevt); + IRQF_TIMER, name, clkevt); if (error) goto err_out_unmap;
writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->irq_ena); writel_relaxed(OMAP_TIMER_INT_OVERFLOW, t->base + t->wakeup);
- pr_info("TI gptimer clockevent: %s%lu Hz at %pOF\n", - of_find_property(np, "ti,timer-alwon", NULL) ? + pr_info("TI gptimer %s: %s%lu Hz at %pOF\n", + name, of_find_property(np, "ti,timer-alwon", NULL) ? "always-on " : "", t->rate, np->parent);
- clockevents_config_and_register(dev, t->rate, - 3, /* Timer internal resynch latency */ + return 0; + +err_out_unmap: + iounmap(t->base); + + return error; +} + +static int __init dmtimer_clockevent_init(struct device_node *np) +{ + struct dmtimer_clockevent *clkevt; + int error; + + clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL); + if (!clkevt) + return -ENOMEM; + + error = dmtimer_clkevt_init_common(clkevt, np, + CLOCK_EVT_FEAT_PERIODIC | + CLOCK_EVT_FEAT_ONESHOT, + cpu_possible_mask, "clockevent", + 300); + if (error) + goto err_out_free; + + clockevents_config_and_register(&clkevt->dev, clkevt->t.rate, + 3, /* Timer internal resync latency */ 0xffffffff);
if (of_machine_is_compatible("ti,am33xx") || of_machine_is_compatible("ti,am43")) { - dev->suspend = omap_clockevent_idle; - dev->resume = omap_clockevent_unidle; + clkevt->dev.suspend = omap_clockevent_idle; + clkevt->dev.resume = omap_clockevent_unidle; }
return 0;
-err_out_unmap: - iounmap(t->base); - err_out_free: kfree(clkevt);
Upstream commit 25de4ce5ed02994aea8bc111d133308f6fd62566 for stable linux-5.10.y. Depends on backported upstream commit 3efe7a878a11c13b5297057bfc1e5639ce1241ce.
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 --- a/arch/arm/boot/dts/dra7-l4.dtsi +++ b/arch/arm/boot/dts/dra7-l4.dtsi @@ -1168,7 +1168,7 @@ timer2: timer@0 { }; };
- 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 @@ timer3: timer@0 { }; };
- 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 --- a/arch/arm/boot/dts/dra7.dtsi +++ b/arch/arm/boot/dts/dra7.dtsi @@ -46,6 +46,7 @@ aliases {
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)>, @@ -1090,3 +1091,22 @@ timer@0 { 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 --- 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 @@ static int __init dmtimer_clockevent_init(struct device_node *np) 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 --- 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,
* Tony Lindgren tony@atomide.com [210517 08:23]:
Upstream commit 25de4ce5ed02994aea8bc111d133308f6fd62566 for stable linux-5.10.y. Depends on backported upstream commit 3efe7a878a11c13b5297057bfc1e5639ce1241ce.
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.
FYI, these patches also apply to linux-5.11.y and linux-5.12.y. This patch applies with fuzz to the related device tree changes though, so please let me know if separate patches are needed.
Regards,
Tony
On Mon, May 17, 2021 at 11:42:26AM +0300, Tony Lindgren wrote:
- Tony Lindgren tony@atomide.com [210517 08:23]:
Upstream commit 25de4ce5ed02994aea8bc111d133308f6fd62566 for stable linux-5.10.y. Depends on backported upstream commit 3efe7a878a11c13b5297057bfc1e5639ce1241ce.
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.
FYI, these patches also apply to linux-5.11.y and linux-5.12.y. This patch applies with fuzz to the related device tree changes though, so please let me know if separate patches are needed.
All now queued up, thanks.
greg k-h
linux-stable-mirror@lists.linaro.org
-
Greg KH -
Tony Lindgren