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- From 3cc8011171186d906c547bc6f0c1f8e350edc7cf Mon Sep 17 00:00:00 2001
- From: Markus Stockhausen <[email protected]>
- Date: Mon, 3 Oct 2022 14:45:21 +0200
- Subject: [PATCH] realtek: resurrect timer driver
- Now that we provide a clock driver for the Reltek SOCs the CPU frequency might
- change on demand. This has direct visible effects during operation
- - the CEVT 4K timer is no longer a stable clocksource
- - after CPU frequencies changes time calculation works wrong
- - sched_clock falls back to kernel default interval (100 Hz)
- - timestamps in dmesg have only 2 digits left
- [ 0.000000] sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps ...
- [ 0.060000] pid_max: default: 32768 minimum: 301
- [ 0.070000] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
- [ 0.070000] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
- [ 0.080000] dyndbg: Ignore empty _ddebug table in a CONFIG_DYNAMIC_DEBUG_CORE build
- [ 0.090000] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, ...
- Looking around where we can start the CEVT timer for RTL930X is a good basis.
- Initially it was developed as a clocksource driver for the broken timer in that
- specific SOC series. Afterwards it was shifted around to the CEVT location,
- got SMP enablement and lost its clocksource feature. So we at least have
- something to copy from. As the timers on these devices are well understood
- the implementation follows this way:
- - leave the RTL930X implementation as is
- - provide a new driver for RTL83XX devices only
- - swap RTL930X driver at a later time
- Like the clock driver this patch contains a self contained module that is SOC
- independet and already provides full support for the RTL838X, RTL839X and
- RTL930X devices. Some of the new (or reestablished) features are:
- - simplified initialization routines
- - SMP setup with CPU hotplug framework
- - derived from LXB clock speed
- - supplied clocksource
- - dedicated register functions for better readability
- - documentation about some caveats
- Signed-off-by: Markus Stockhausen <[email protected]>
- [remove unused header includes, remove old CONFIG_MIPS dependency, add
- REALTEK_ prefix to driver symbol]
- Signed-off-by: Sander Vanheule <[email protected]>
- ---
- drivers/clocksource/Kconfig | 12 +++
- drivers/clocksource/Makefile | 1 +
- include/linux/cpuhotplug.h | 1 +
- 3 files changed, 14 insertions(+)
- --- a/drivers/clocksource/Kconfig
- +++ b/drivers/clocksource/Kconfig
- @@ -127,6 +127,17 @@ config RDA_TIMER
- help
- Enables the support for the RDA Micro timer driver.
-
- +config REALTEK_OTTO_TIMER
- + bool "Clocksource/timer for the Realtek Otto platform"
- + select COMMON_CLK
- + select TIMER_OF
- + help
- + This driver adds support for the timers found in the Realtek RTL83xx
- + and RTL93xx SoCs series. This includes chips such as RTL8380, RTL8381
- + and RTL832, as well as chips from the RTL839x series, such as RTL8390
- + RT8391, RTL8392, RTL8393 and RTL8396 and chips of the RTL930x series
- + such as RTL9301, RTL9302 or RTL9303.
- +
- config SUN4I_TIMER
- bool "Sun4i timer driver" if COMPILE_TEST
- depends on HAS_IOMEM
- --- a/drivers/clocksource/Makefile
- +++ b/drivers/clocksource/Makefile
- @@ -58,6 +58,7 @@ obj-$(CONFIG_MILBEAUT_TIMER) += timer-mi
- obj-$(CONFIG_SPRD_TIMER) += timer-sprd.o
- obj-$(CONFIG_NPCM7XX_TIMER) += timer-npcm7xx.o
- obj-$(CONFIG_RDA_TIMER) += timer-rda.o
- +obj-$(CONFIG_REALTEK_OTTO_TIMER) += timer-rtl-otto.o
-
- obj-$(CONFIG_ARC_TIMERS) += arc_timer.o
- obj-$(CONFIG_ARM_ARCH_TIMER) += arm_arch_timer.o
- --- a/include/linux/cpuhotplug.h
- +++ b/include/linux/cpuhotplug.h
- @@ -176,6 +176,7 @@ enum cpuhp_state {
- CPUHP_AP_MARCO_TIMER_STARTING,
- CPUHP_AP_MIPS_GIC_TIMER_STARTING,
- CPUHP_AP_ARC_TIMER_STARTING,
- + CPUHP_AP_REALTEK_TIMER_STARTING,
- CPUHP_AP_RISCV_TIMER_STARTING,
- CPUHP_AP_CLINT_TIMER_STARTING,
- CPUHP_AP_CSKY_TIMER_STARTING,
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