NVIDIA Tegra clocksource driver improvements

Hello,

This series primarily unifies the driver code across all Tegra SoC generations. In a result the clocksources are allocated per-CPU on older Tegra's and have a higher rating than the arch-timer where appropriate, the newer Tegra210 is getting support for microsecond clocksource and the driver's code is getting much cleaner.

The series was extensively tested on Tegra20 and Tegra30.

Changelog:

v4: In the comment to v3 Peter De Schrijver pointed out that arch-timer
isn't affected by DVFS changes and thus it is preferred over tegra-timer on [T114, T210). Added new patch to address that: "Lower clocksource rating for some Tegra's".

Daniel Lezcano suggested that it will be worthwhile to rename driver's source file as driver now covers more SoC generations than it initially did. Hence the new "Rename timer-tegra20.c to timer-tegra.c" patch.

v3: Fixed compilation on ARM64. Turned out that it doesn't have the
delay-timer, thanks to Nicolas Chauvet for the report.

Added new "Support COMPILE_TEST universally" patch for better compile-test coverage.

v2: Rebased on recent linux-next. Now all of #ifdef's are removed from the
code due to the recent patch that generalized persistent clocksource.

Couple other minor cosmetic changes.

Dmitry Osipenko (10):
clocksource/drivers/tegra: Support per-CPU timers on all Tegra's clocksource/drivers/tegra: Unify timer code clocksource/drivers/tegra: Reset hardware state on init clocksource/drivers/tegra: Replace readl/writel with relaxed versions clocksource/drivers/tegra: Release all IRQ's on request_irq() error clocksource/drivers/tegra: Minor code clean up clocksource/drivers/tegra: Use SPDX identifier clocksource/drivers/tegra: Support COMPILE_TEST universally clocksource/drivers/tegra: Lower clocksource rating for some Tegra's clocksource/drivers/tegra: Rename timer-tegra20.c to timer-tegra.c

 drivers/clocksource/Kconfig                   |   2 +-
 drivers/clocksource/Makefile                  |   2 +-
 .../{timer-tegra20.c => timer-tegra.c}        | 296 +++++++++---------
 3 files changed, 148 insertions(+), 152 deletions(-)
 rename drivers/clocksource/{timer-tegra20.c => timer-tegra.c} (54%)

2.21.0