clocksource/drivers/timer-ti-dm: Fix regression from errata i940 fix

The existing fix for errata i940 causes a conflict for IPU2 which is
using timer 3 and 4. From arch/arm/boot/dts/dra7-ipu-dsp-common.dtsi:

&ipu2 {
mboxes = <&mailbox6 &mbox_ipu2_ipc3x>;
ti,timers = <&timer3>;
ti,watchdog-timers = <&timer4>, <&timer9>;
};

The conflict was noticed when booting mainline on the BeagleBoard X15
which has a TI AM5728 SoC:

remoteproc remoteproc1: 55020000.ipu is available
remoteproc remoteproc1: powering up 55020000.ipu
remoteproc remoteproc1: Booting fw image dra7-ipu2-fw.xem4
omap-rproc 55020000.ipu: could not get timer platform device
omap-rproc 55020000.ipu: omap_rproc_enable_timers failed: -19
remoteproc remoteproc1: can't start rproc 55020000.ipu: -19

This change modifies the errata fix to instead use timer 15 and 16 which
resolves the timer conflict.

It does not appear to introduce any latency regression. Results from
cyclictest with original errata fix using dmtimer 3 and 4:

# cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0
policy: fifo: loadavg: 0.02 0.03 0.05

T: 0 ( 1449) P:80 I:200 C: 800368 Min: 0 Act: 32 Avg: 22 Max: 128
T: 1 ( 1450) P:80 I:200 C: 800301 Min: 0 Act: 12 Avg: 23 Max: 70

The results after the change to dmtimer 15 and 16:

# cyclictest --mlockall --smp --priority=80 --interval=200 --distance=0
policy: fifo: loadavg: 0.36 0.19 0.07

T: 0 ( 1711) P:80 I:200 C: 759599 Min: 0 Act: 6 Avg: 22 Max: 108
T: 1 ( 1712) P:80 I:200 C: 759539 Min: 0 Act: 19 Avg: 23 Max: 79

Fixes: 25de4ce5ed02 ("clocksource/drivers/timer-ti-dm: Handle dra7 timer wrap errata i940")
Link: https://lore.kernel.org/linux-omap/YfWsG0p6to3IJuvE@x1/
Suggested-by: Suman Anna <[e-mail]>
Reviewed-by: Tony Lindgren <[e-mail]>
Signed-off-by: Drew Fustini <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Daniel Lezcano <[e-mail]>

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

···
 				ti,timer-pwm;
 			};
 		};
-
-		target-module@2c000 {			/* 0x4882c000, ap 17 02.0 */
+		timer15_target: target-module@2c000 {	/* 0x4882c000, ap 17 02.0 */
 			compatible = "ti,sysc-omap4-timer", "ti,sysc";
 			reg = <0x2c000 0x4>,
 			      <0x2c010 0x4>;
···
 			};
 		};
 
-		target-module@2e000 {			/* 0x4882e000, ap 19 14.0 */
+		timer16_target: target-module@2e000 {	/* 0x4882e000, ap 19 14.0 */
 			compatible = "ti,sysc-omap4-timer", "ti,sysc";
 			reg = <0x2e000 0x4>,
 			      <0x2e010 0x4>;

arch/arm/boot/dts/dra7.dtsi

···
 };
 
 /* Local timers, see ARM architected timer wrap erratum i940 */
-&timer3_target {
+&timer15_target {
 	ti,no-reset-on-init;
 	ti,no-idle;
 	timer@0 {
-		assigned-clocks = <&l4per_clkctrl DRA7_L4PER_TIMER3_CLKCTRL 24>;
+		assigned-clocks = <&l4per3_clkctrl DRA7_L4PER3_TIMER15_CLKCTRL 24>;
 		assigned-clock-parents = <&timer_sys_clk_div>;
 	};
 };
 
-&timer4_target {
+&timer16_target {
 	ti,no-reset-on-init;
 	ti,no-idle;
 	timer@0 {
-		assigned-clocks = <&l4per_clkctrl DRA7_L4PER_TIMER4_CLKCTRL 24>;
+		assigned-clocks = <&l4per3_clkctrl DRA7_L4PER3_TIMER16_CLKCTRL 24>;
 		assigned-clock-parents = <&timer_sys_clk_div>;
 	};
 };

drivers/clocksource/timer-ti-dm-systimer.c

···
 		return 0;
 	}
 
-	if (pa == 0x48034000)		/* dra7 dmtimer3 */
+	if (pa == 0x4882c000)           /* dra7 dmtimer15 */
 		return dmtimer_percpu_timer_init(np, 0);
-	else if (pa == 0x48036000)	/* dra7 dmtimer4 */
+	else if (pa == 0x4882e000)      /* dra7 dmtimer16 */
 		return dmtimer_percpu_timer_init(np, 1);
 
 	return 0;