target/linux/realtek/patches-5.10/302-clocksource-add-otto-driver.patch

   1 From 3cc8011171186d906c547bc6f0c1f8e350edc7cf Mon Sep 17 00:00:00 2001
   2 From: Markus Stockhausen <markus.stockhausen@gmx.de>
   3 Date: Mon, 3 Oct 2022 14:45:21 +0200
   4 Subject: [PATCH] realtek: resurrect timer driver
   5
   6 Now that we provide a clock driver for the Reltek SOCs the CPU frequency might
   7 change on demand. This has direct visible effects during operation
   8
   9 - the CEVT 4K timer is no longer a stable clocksource
  10 - after CPU frequencies changes time calculation works wrong
  11 - sched_clock falls back to kernel default interval (100 Hz)
  12 - timestamps in dmesg have only 2 digits left
  13
  14 [    0.000000] sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps ...
  15 [    0.060000] pid_max: default: 32768 minimum: 301
  16 [    0.070000] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
  17 [    0.070000] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
  18 [    0.080000] dyndbg: Ignore empty _ddebug table in a CONFIG_DYNAMIC_DEBUG_CORE build
  19 [    0.090000] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, ...
  20
  21 Looking around where we can start the CEVT timer for RTL930X is a good basis.
  22 Initially it was developed as a clocksource driver for the broken timer in that
  23 specific SOC series. Afterwards it was shifted around to the CEVT location,
  24 got SMP enablement and lost its clocksource feature. So we at least have
  25 something to copy from. As the timers on these devices are well understood
  26 the implementation follows this way:
  27
  28 - leave the RTL930X implementation as is
  29 - provide a new driver for RTL83XX devices only
  30 - swap RTL930X driver at a later time
  31
  32 Like the clock driver this patch contains a self contained module that is SOC
  33 independet and already provides full support for the RTL838X, RTL839X and
  34 RTL930X devices. Some of the new (or reestablished) features are:
  35
  36 - simplified initialization routines
  37 - SMP setup with CPU hotplug framework
  38 - derived from LXB clock speed
  39 - supplied clocksource
  40 - dedicated register functions for better readability
  41 - documentation about some caveats
  42
  43 Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>
  44 [remove unused header includes, remove old CONFIG_MIPS dependency, add
  45 REALTEK_ prefix to driver symbol]
  46 Signed-off-by: Sander Vanheule <sander@svanheule.net>
  47
  48 ---
  49  drivers/clocksource/Kconfig                   | 12 +++
  50  drivers/clocksource/Makefile                  |  1 +
  51  include/linux/cpuhotplug.h                    |  1 +
  52  3 files changed, 14 insertions(+)
  53
  54 --- a/drivers/clocksource/Kconfig
  55 +++ b/drivers/clocksource/Kconfig
  56 @@ -127,6 +127,17 @@ config RDA_TIMER
  57         help
  58           Enables the support for the RDA Micro timer driver.
  59
  60 +config REALTEK_OTTO_TIMER
  61 +       bool "Clocksource/timer for the Realtek Otto platform"
  62 +       select COMMON_CLK
  63 +       select TIMER_OF
  64 +       help
  65 +         This driver adds support for the timers found in the Realtek RTL83xx
  66 +         and RTL93xx SoCs series. This includes chips such as RTL8380, RTL8381
  67 +         and RTL832, as well as chips from the RTL839x series, such as RTL8390
  68 +         RT8391, RTL8392, RTL8393 and RTL8396 and chips of the RTL930x series
  69 +         such as RTL9301, RTL9302 or RTL9303.
  70 +
  71  config SUN4I_TIMER
  72         bool "Sun4i timer driver" if COMPILE_TEST
  73         depends on HAS_IOMEM
  74 --- a/drivers/clocksource/Makefile
  75 +++ b/drivers/clocksource/Makefile
  76 @@ -63,6 +63,7 @@ obj-$(CONFIG_MILBEAUT_TIMER)  += timer-mi
  77  obj-$(CONFIG_SPRD_TIMER)       += timer-sprd.o
  78  obj-$(CONFIG_NPCM7XX_TIMER)    += timer-npcm7xx.o
  79  obj-$(CONFIG_RDA_TIMER)                += timer-rda.o
  80 +obj-$(CONFIG_REALTEK_OTTO_TIMER)       += timer-rtl-otto.o
  81
  82  obj-$(CONFIG_ARC_TIMERS)               += arc_timer.o
  83  obj-$(CONFIG_ARM_ARCH_TIMER)           += arm_arch_timer.o
  84 --- a/include/linux/cpuhotplug.h
  85 +++ b/include/linux/cpuhotplug.h
  86 @@ -133,6 +133,7 @@ enum cpuhp_state {
  87         CPUHP_AP_MARCO_TIMER_STARTING,
  88         CPUHP_AP_MIPS_GIC_TIMER_STARTING,
  89         CPUHP_AP_ARC_TIMER_STARTING,
  90 +       CPUHP_AP_REALTEK_TIMER_STARTING,
  91         CPUHP_AP_RISCV_TIMER_STARTING,
  92         CPUHP_AP_CLINT_TIMER_STARTING,
  93         CPUHP_AP_CSKY_TIMER_STARTING,