From 25de4ce5ed02994aea8bc111d133308f6fd62566 Mon Sep 17 00:00:00 2001 From: Tony Lindgren Date: Tue, 23 Mar 2021 09:43:26 +0200 Subject: 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 Cc: Tero Kristo Signed-off-by: Tony Lindgren Signed-off-by: Daniel Lezcano Link: https://lore.kernel.org/r/20210323074326.28302-3-tony@atomide.com --- arch/arm/boot/dts/dra7.dtsi | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+) (limited to 'arch/arm/boot/dts/dra7.dtsi') diff --git a/arch/arm/boot/dts/dra7.dtsi b/arch/arm/boot/dts/dra7.dtsi index ce1194744f84..53d68786a61f 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 = , , , @@ -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>; + }; +}; -- cgit