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
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 @@ 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
index ce11947..53d6878 100644
--- 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)>,
@@ -1241,3 +1242,22 @@ 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>;
+ };
+};