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Commit 5babc397 authored by Tony Lindgren's avatar Tony Lindgren Committed by Greg Kroah-Hartman
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clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940 

commit 25de4ce5ed02994aea8bc111d133308f6fd62566 upstream.

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.

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: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Keerthy <j-keerthy@ti.com>
Cc: Tero Kristo <kristo@kernel.org>
[tony@atomide.com: backported to 5.4.y]
Signed-off-by: default avatarTony Lindgren <tony@atomide.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent aad8f1d8

arch/arm/boot/dts/dra7-l4.dtsi

+2 −2
Original line number Diff line number Diff line
@@ -1176,7 +1176,7 @@ 
			};

		};



		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";

			ti,hwmods = "timer3";

			reg = <0x34000 0x4>,
@@ -1204,7 +1204,7 @@ 
			};

		};



		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";

			ti,hwmods = "timer4";

			reg = <0x36000 0x4>,

arch/arm/boot/dts/dra7.dtsi

+20 −0
Original line number Diff line number Diff line
@@ -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)>,
@@ -766,3 +767,22 @@ 


#include "dra7-l4.dtsi"

#include "dra7xx-clocks.dtsi"



/* 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>;

	};

};

arch/arm/mach-omap2/board-generic.c

+2 −2
Original line number Diff line number Diff line
@@ -327,7 +327,7 @@ DT_MACHINE_START(DRA74X_DT, "Generic DRA74X (Flattened Device Tree)") 
	.init_late	= dra7xx_init_late,

	.init_irq	= omap_gic_of_init,

	.init_machine	= omap_generic_init,

	.init_time	= omap5_realtime_timer_init,

	.init_time	= omap3_gptimer_timer_init,

	.dt_compat	= dra74x_boards_compat,

	.restart	= omap44xx_restart,

MACHINE_END
@@ -350,7 +350,7 @@ DT_MACHINE_START(DRA72X_DT, "Generic DRA72X (Flattened Device Tree)") 
	.init_late	= dra7xx_init_late,

	.init_irq	= omap_gic_of_init,

	.init_machine	= omap_generic_init,

	.init_time	= omap5_realtime_timer_init,

	.init_time	= omap3_gptimer_timer_init,

	.dt_compat	= dra72x_boards_compat,

	.restart	= omap44xx_restart,

MACHINE_END

arch/arm/mach-omap2/timer.c

+52 −1
Original line number Diff line number Diff line
@@ -42,6 +42,7 @@ 
#include <linux/platform_device.h>

#include <linux/platform_data/dmtimer-omap.h>

#include <linux/sched_clock.h>

#include <linux/cpu.h>



#include <asm/mach/time.h>
@@ -420,6 +421,53 @@ static void __init dmtimer_clkevt_init_common(struct dmtimer_clockevent *clkevt, 
		timer->rate);

}



static DEFINE_PER_CPU(struct dmtimer_clockevent, dmtimer_percpu_timer);



static int omap_gptimer_starting_cpu(unsigned int cpu)

{

	struct dmtimer_clockevent *clkevt = per_cpu_ptr(&dmtimer_percpu_timer, cpu);

	struct clock_event_device *dev = &clkevt->dev;

	struct omap_dm_timer *timer = &clkevt->timer;



	clockevents_config_and_register(dev, timer->rate, 3, ULONG_MAX);

	irq_force_affinity(dev->irq, cpumask_of(cpu));



	return 0;

}



static int __init dmtimer_percpu_quirk_init(void)

{

	struct dmtimer_clockevent *clkevt;

	struct clock_event_device *dev;

	struct device_node *arm_timer;

	struct omap_dm_timer *timer;

	int cpu = 0;



	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;

	}



	for_each_possible_cpu(cpu) {

		clkevt = per_cpu_ptr(&dmtimer_percpu_timer, cpu);

		dev = &clkevt->dev;

		timer = &clkevt->timer;



		dmtimer_clkevt_init_common(clkevt, 0, "timer_sys_ck",

					   CLOCK_EVT_FEAT_ONESHOT,

					   cpumask_of(cpu),

					   "assigned-clock-parents",

					   500, "percpu timer");

	}



	cpuhp_setup_state(CPUHP_AP_OMAP_DM_TIMER_STARTING,

			  "clockevents/omap/gptimer:starting",

			  omap_gptimer_starting_cpu, NULL);



	return 0;

}



/* Clocksource code */

static struct omap_dm_timer clksrc;

static bool use_gptimer_clksrc __initdata;
@@ -564,6 +612,9 @@ static void __init __omap_sync32k_timer_init(int clkev_nr, const char *clkev_src 
					3, /* Timer internal resynch latency */

					0xffffffff);



	if (soc_is_dra7xx())

		dmtimer_percpu_quirk_init();



	/* Enable the use of clocksource="gp_timer" kernel parameter */

	if (use_gptimer_clksrc || gptimer)

		omap2_gptimer_clocksource_init(clksrc_nr, clksrc_src,
@@ -591,7 +642,7 @@ void __init omap3_secure_sync32k_timer_init(void) 
#endif /* CONFIG_ARCH_OMAP3 */



#if defined(CONFIG_ARCH_OMAP3) || defined(CONFIG_SOC_AM33XX) || \

	defined(CONFIG_SOC_AM43XX)

	defined(CONFIG_SOC_AM43XX) || defined(CONFIG_SOC_DRA7XX)

void __init omap3_gptimer_timer_init(void)

{

	__omap_sync32k_timer_init(2, "timer_sys_ck", NULL,

drivers/clk/ti/clk-7xx.c

+1 −0
Original line number Diff line number Diff line
@@ -793,6 +793,7 @@ static struct ti_dt_clk dra7xx_clks[] = { 
	DT_CLK(NULL, "timer_32k_ck", "sys_32k_ck"),

	DT_CLK(NULL, "sys_clkin_ck", "timer_sys_clk_div"),

	DT_CLK(NULL, "sys_clkin", "sys_clkin1"),

	DT_CLK(NULL, "timer_sys_ck", "timer_sys_clk_div"),

	DT_CLK(NULL, "atl_dpll_clk_mux", "atl-clkctrl:0000:24"),

	DT_CLK(NULL, "atl_gfclk_mux", "atl-clkctrl:0000:26"),

	DT_CLK(NULL, "dcan1_sys_clk_mux", "wkupaon-clkctrl:0068:24"),