Merge tag 'timers-core-2024-07-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "Updates for timers, timekeeping and related functionality:

  Core:

   - Make the takeover of a hrtimer based broadcast timer reliable
     during CPU hot-unplug. The current implementation suffers from a
     race which can lead to broadcast timer starvation in the worst
     case.

   - VDSO related cleanups and simplifications

   - Small cleanups and enhancements all over the place

  PTP:

   - Replace the architecture specific base clock to clocksource, e.g.
     ART to TSC, conversion function with generic functionality to avoid
     exposing such internals to drivers and convert all existing drivers
     over. This also allows to provide functionality which converts the
     other way round in the core code based on the same parameter set.

   - Provide a function to convert CLOCK_REALTIME to the base clock to
     support the upcoming PPS output driver on Intel platforms.

  Drivers:

   - A set of Device Tree bindings for new hardware

   - Cleanups and enhancements all over the place"

* tag 'timers-core-2024-07-14' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (30 commits)
  clocksource/drivers/realtek: Add timer driver for rtl-otto platforms
  dt-bindings: timer: Add schema for realtek,otto-timer
  dt-bindings: timer: Add SOPHGO SG2002 clint
  dt-bindings: timer: renesas,tmu: Add R-Car Gen2 support
  dt-bindings: timer: renesas,tmu: Add RZ/G1 support
  dt-bindings: timer: renesas,tmu: Add R-Mobile APE6 support
  clocksource/drivers/mips-gic-timer: Correct sched_clock width
  clocksource/drivers/mips-gic-timer: Refine rating computation
  clocksource/drivers/sh_cmt: Address race condition for clock events
  clocksource/driver/arm_global_timer: Remove unnecessary ‘0’ values from err
  clocksource/drivers/arm_arch_timer: Remove unnecessary ‘0’ values from irq
  tick/broadcast: Make takeover of broadcast hrtimer reliable
  tick/sched: Combine WARN_ON_ONCE and print_once
  x86/vdso: Remove unused include
  x86/vgtod: Remove unused typedef gtod_long_t
  x86/vdso: Fix function reference in comment
  vdso: Add comment about reason for vdso struct ordering
  vdso/gettimeofday: Clarify comment about open coded function
  timekeeping: Add missing kernel-doc function comments
  tick: Remove unnused tick_nohz_get_idle_calls()
  ...

33 files changed, 647 insertions, 131 deletions

diff --git a/Documentation/devicetree/bindings/timer/realtek,otto-timer.yaml b/Documentation/devicetree/bindings/timer/realtek,otto-timer.yaml
new file mode 100644
index 000000000000..7b6ec2c69484
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/realtek,otto-timer.yaml
@@ -0,0 +1,63 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/realtek,otto-timer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Realtek Otto SoCs Timer/Counter
+
+description:
+  Realtek SoCs support a number of timers/counters. These are used
+  as a per CPU clock event generator and an overall CPU clocksource.
+
+maintainers:
+  - Chris Packham <chris.packham@alliedtelesis.co.nz>
+
+properties:
+  $nodename:
+    pattern: "^timer@[0-9a-f]+$"
+
+  compatible:
+    items:
+      - enum:
+          - realtek,rtl9302-timer
+      - const: realtek,otto-timer
+
+  reg:
+    items:
+      - description: timer0 registers
+      - description: timer1 registers
+      - description: timer2 registers
+      - description: timer3 registers
+      - description: timer4 registers
+
+  clocks:
+    maxItems: 1
+
+  interrupts:
+    items:
+      - description: timer0 interrupt
+      - description: timer1 interrupt
+      - description: timer2 interrupt
+      - description: timer3 interrupt
+      - description: timer4 interrupt
+
+required:
+  - compatible
+  - reg
+  - clocks
+  - interrupts
+
+additionalProperties: false
+
+examples:
+  - |
+    timer@3200 {
+      compatible = "realtek,rtl9302-timer", "realtek,otto-timer";
+      reg = <0x3200 0x10>, <0x3210 0x10>, <0x3220 0x10>,
+            <0x3230 0x10>, <0x3240 0x10>;
+
+      interrupt-parent = <&intc>;
+      interrupts = <7>, <8>, <9>, <10>, <11>;
+      clocks = <&lx_clk>;
+    };
diff --git a/Documentation/devicetree/bindings/timer/renesas,tmu.yaml b/Documentation/devicetree/bindings/timer/renesas,tmu.yaml
index 360a5cf1ae9c..b6dd98d956f3 100644
--- a/Documentation/devicetree/bindings/timer/renesas,tmu.yaml
+++ b/Documentation/devicetree/bindings/timer/renesas,tmu.yaml
@@ -21,13 +21,24 @@ properties:
   compatible:
     items:
       - enum:
+          - renesas,tmu-r8a73a4  # R-Mobile APE6
           - renesas,tmu-r8a7740  # R-Mobile A1
+          - renesas,tmu-r8a7742  # RZ/G1H
+          - renesas,tmu-r8a7743  # RZ/G1M
+          - renesas,tmu-r8a7744  # RZ/G1N
+          - renesas,tmu-r8a7745  # RZ/G1E
+          - renesas,tmu-r8a77470 # RZ/G1C
           - renesas,tmu-r8a774a1 # RZ/G2M
           - renesas,tmu-r8a774b1 # RZ/G2N
           - renesas,tmu-r8a774c0 # RZ/G2E
           - renesas,tmu-r8a774e1 # RZ/G2H
           - renesas,tmu-r8a7778  # R-Car M1A
           - renesas,tmu-r8a7779  # R-Car H1
+          - renesas,tmu-r8a7790  # R-Car H2
+          - renesas,tmu-r8a7791  # R-Car M2-W
+          - renesas,tmu-r8a7792  # R-Car V2H
+          - renesas,tmu-r8a7793  # R-Car M2-N
+          - renesas,tmu-r8a7794  # R-Car E2
           - renesas,tmu-r8a7795  # R-Car H3
           - renesas,tmu-r8a7796  # R-Car M3-W
           - renesas,tmu-r8a77961 # R-Car M3-W+
@@ -94,6 +105,7 @@ if:
       compatible:
         contains:
           enum:
+            - renesas,tmu-r8a73a4
             - renesas,tmu-r8a7740
             - renesas,tmu-r8a7778
             - renesas,tmu-r8a7779
diff --git a/Documentation/devicetree/bindings/timer/sifive,clint.yaml b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
index fced6f2d8ecb..b42d43d2de48 100644
--- a/Documentation/devicetree/bindings/timer/sifive,clint.yaml
+++ b/Documentation/devicetree/bindings/timer/sifive,clint.yaml
@@ -40,6 +40,7 @@ properties:
               - allwinner,sun20i-d1-clint
               - sophgo,cv1800b-clint
               - sophgo,cv1812h-clint
+              - sophgo,sg2002-clint
               - thead,th1520-clint
           - const: thead,c900-clint
       - items:
diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h
index 405efb3e4996..94408a784c8e 100644
--- a/arch/x86/include/asm/tsc.h
+++ b/arch/x86/include/asm/tsc.h
@@ -28,9 +28,6 @@ static inline cycles_t get_cycles(void)
 }
 #define get_cycles get_cycles
 
-extern struct system_counterval_t convert_art_to_tsc(u64 art);
-extern struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns);
-
 extern void tsc_early_init(void);
 extern void tsc_init(void);
 extern void mark_tsc_unstable(char *reason);
diff --git a/arch/x86/include/asm/vdso/gettimeofday.h b/arch/x86/include/asm/vdso/gettimeofday.h
index 0ef36190abe6..b2d2df026f6e 100644
--- a/arch/x86/include/asm/vdso/gettimeofday.h
+++ b/arch/x86/include/asm/vdso/gettimeofday.h
@@ -328,9 +328,8 @@ static __always_inline u64 vdso_calc_ns(const struct vdso_data *vd, u64 cycles,
 	 * due to unsigned comparison.
 	 *
 	 * Due to the MSB/Sign-bit being used as invalid marker (see
-	 * arch_vdso_cycles_valid() above), the effective mask is S64_MAX,
-	 * but that case is also unlikely and will also take the unlikely path
-	 * here.
+	 * arch_vdso_cycles_ok() above), the effective mask is S64_MAX, but that
+	 * case is also unlikely and will also take the unlikely path here.
 	 */
 	if (unlikely(delta > vd->max_cycles)) {
 		/*
diff --git a/arch/x86/include/asm/vdso/vsyscall.h b/arch/x86/include/asm/vdso/vsyscall.h
index be199a9b2676..93226281b450 100644
--- a/arch/x86/include/asm/vdso/vsyscall.h
+++ b/arch/x86/include/asm/vdso/vsyscall.h
@@ -4,7 +4,6 @@
 
 #ifndef __ASSEMBLY__
 
-#include <linux/hrtimer.h>
 #include <linux/timekeeper_internal.h>
 #include <vdso/datapage.h>
 #include <asm/vgtod.h>
diff --git a/arch/x86/include/asm/vgtod.h b/arch/x86/include/asm/vgtod.h
index 7aa38b2ad8a9..a0ce291abcae 100644
--- a/arch/x86/include/asm/vgtod.h
+++ b/arch/x86/include/asm/vgtod.h
@@ -14,11 +14,6 @@
 
 #include <uapi/linux/time.h>
 
-#ifdef BUILD_VDSO32_64
-typedef u64 gtod_long_t;
-#else
-typedef unsigned long gtod_long_t;
-#endif
 #endif /* CONFIG_GENERIC_GETTIMEOFDAY */
 
 #endif /* _ASM_X86_VGTOD_H */
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 06b170759e5b..d4462fb26299 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -50,9 +50,9 @@ int tsc_clocksource_reliable;
 
 static int __read_mostly tsc_force_recalibrate;
 
-static u32 art_to_tsc_numerator;
-static u32 art_to_tsc_denominator;
-static u64 art_to_tsc_offset;
+static struct clocksource_base art_base_clk = {
+	.id    = CSID_X86_ART,
+};
 static bool have_art;
 
 struct cyc2ns {
@@ -1074,7 +1074,7 @@ core_initcall(cpufreq_register_tsc_scaling);
  */
 static void __init detect_art(void)
 {
-	unsigned int unused[2];
+	unsigned int unused;
 
 	if (boot_cpu_data.cpuid_level < ART_CPUID_LEAF)
 		return;
@@ -1089,13 +1089,14 @@ static void __init detect_art(void)
 	    tsc_async_resets)
 		return;
 
-	cpuid(ART_CPUID_LEAF, &art_to_tsc_denominator,
-	      &art_to_tsc_numerator, unused, unused+1);
+	cpuid(ART_CPUID_LEAF, &art_base_clk.denominator,
+	      &art_base_clk.numerator, &art_base_clk.freq_khz, &unused);
 
-	if (art_to_tsc_denominator < ART_MIN_DENOMINATOR)
+	art_base_clk.freq_khz /= KHZ;
+	if (art_base_clk.denominator < ART_MIN_DENOMINATOR)
 		return;
 
-	rdmsrl(MSR_IA32_TSC_ADJUST, art_to_tsc_offset);
+	rdmsrl(MSR_IA32_TSC_ADJUST, art_base_clk.offset);
 
 	/* Make this sticky over multiple CPU init calls */
 	setup_force_cpu_cap(X86_FEATURE_ART);
@@ -1296,67 +1297,6 @@ int unsynchronized_tsc(void)
 	return 0;
 }
 
-/*
- * Convert ART to TSC given numerator/denominator found in detect_art()
- */
-struct system_counterval_t convert_art_to_tsc(u64 art)
-{
-	u64 tmp, res, rem;
-
-	rem = do_div(art, art_to_tsc_denominator);
-
-	res = art * art_to_tsc_numerator;
-	tmp = rem * art_to_tsc_numerator;
-
-	do_div(tmp, art_to_tsc_denominator);
-	res += tmp + art_to_tsc_offset;
-
-	return (struct system_counterval_t) {
-		.cs_id	= have_art ? CSID_X86_TSC : CSID_GENERIC,
-		.cycles	= res,
-	};
-}
-EXPORT_SYMBOL(convert_art_to_tsc);
-
-/**
- * convert_art_ns_to_tsc() - Convert ART in nanoseconds to TSC.
- * @art_ns: ART (Always Running Timer) in unit of nanoseconds
- *
- * PTM requires all timestamps to be in units of nanoseconds. When user
- * software requests a cross-timestamp, this function converts system timestamp
- * to TSC.
- *
- * This is valid when CPU feature flag X86_FEATURE_TSC_KNOWN_FREQ is set
- * indicating the tsc_khz is derived from CPUID[15H]. Drivers should check
- * that this flag is set before conversion to TSC is attempted.
- *
- * Return:
- * struct system_counterval_t - system counter value with the ID of the
- *	corresponding clocksource:
- *	cycles:		System counter value
- *	cs_id:		The clocksource ID for validating comparability
- */
-
-struct system_counterval_t convert_art_ns_to_tsc(u64 art_ns)
-{
-	u64 tmp, res, rem;
-
-	rem = do_div(art_ns, USEC_PER_SEC);
-
-	res = art_ns * tsc_khz;
-	tmp = rem * tsc_khz;
-
-	do_div(tmp, USEC_PER_SEC);
-	res += tmp;
-
-	return (struct system_counterval_t) {
-		.cs_id	= have_art ? CSID_X86_TSC : CSID_GENERIC,
-		.cycles	= res,
-	};
-}
-EXPORT_SYMBOL(convert_art_ns_to_tsc);
-
-
 static void tsc_refine_calibration_work(struct work_struct *work);
 static DECLARE_DELAYED_WORK(tsc_irqwork, tsc_refine_calibration_work);
 /**
@@ -1458,8 +1398,10 @@ out:
 	if (tsc_unstable)
 		goto unreg;
 
-	if (boot_cpu_has(X86_FEATURE_ART))
+	if (boot_cpu_has(X86_FEATURE_ART)) {
 		have_art = true;
+		clocksource_tsc.base = &art_base_clk;
+	}
 	clocksource_register_khz(&clocksource_tsc, tsc_khz);
 unreg:
 	clocksource_unregister(&clocksource_tsc_early);
@@ -1484,8 +1426,10 @@ static int __init init_tsc_clocksource(void)
 	 * the refined calibration and directly register it as a clocksource.
 	 */
 	if (boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) {
-		if (boot_cpu_has(X86_FEATURE_ART))
+		if (boot_cpu_has(X86_FEATURE_ART)) {
 			have_art = true;
+			clocksource_tsc.base = &art_base_clk;
+		}
 		clocksource_register_khz(&clocksource_tsc, tsc_khz);
 		clocksource_unregister(&clocksource_tsc_early);
 
@@ -1509,10 +1453,12 @@ static bool __init determine_cpu_tsc_frequencies(bool early)
 
 	if (early) {
 		cpu_khz = x86_platform.calibrate_cpu();
-		if (tsc_early_khz)
+		if (tsc_early_khz) {
 			tsc_khz = tsc_early_khz;
-		else
+		} else {
 			tsc_khz = x86_platform.calibrate_tsc();
+			clocksource_tsc.freq_khz = tsc_khz;
+		}
 	} else {
 		/* We should not be here with non-native cpu calibration */
 		WARN_ON(x86_platform.calibrate_cpu != native_calibrate_cpu);
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 34faa0320ece..95dd4660b5b6 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -134,6 +134,16 @@ 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" if COMPILE_TEST
+	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
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 4bb856e4df55..22743785299e 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_MILBEAUT_TIMER)	+= timer-milbeaut.o
 obj-$(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
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 5bb43cc1a8df..aeafc74181f0 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -1556,7 +1556,7 @@ static int __init
 arch_timer_mem_frame_register(struct arch_timer_mem_frame *frame)
 {
 	void __iomem *base;
-	int ret, irq = 0;
+	int ret, irq;
 
 	if (arch_timer_mem_use_virtual)
 		irq = frame->virt_irq;
diff --git a/drivers/clocksource/arm_global_timer.c b/drivers/clocksource/arm_global_timer.c
index ab1c8c2b66b8..a05cfaab5f84 100644
--- a/drivers/clocksource/arm_global_timer.c
+++ b/drivers/clocksource/arm_global_timer.c
@@ -343,7 +343,7 @@ static int __init global_timer_of_register(struct device_node *np)
 {
 	struct clk *gt_clk;
 	static unsigned long gt_clk_rate;
-	int err = 0;
+	int err;
 
 	/*
 	 * In A9 r2p0 the comparators for each processor with the global timer
diff --git a/drivers/clocksource/mips-gic-timer.c b/drivers/clocksource/mips-gic-timer.c
index b3ae38f36720..110347707ff9 100644
--- a/drivers/clocksource/mips-gic-timer.c
+++ b/drivers/clocksource/mips-gic-timer.c
@@ -19,6 +19,7 @@
 static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);
 static int gic_timer_irq;
 static unsigned int gic_frequency;
+static unsigned int gic_count_width;
 static bool __read_mostly gic_clock_unstable;
 
 static void gic_clocksource_unstable(char *reason);
@@ -186,18 +187,21 @@ static void gic_clocksource_unstable(char *reason)
 
 static int __init __gic_clocksource_init(void)
 {
-	unsigned int count_width;
 	int ret;
 
 	/* Set clocksource mask. */
-	count_width = read_gic_config() & GIC_CONFIG_COUNTBITS;
-	count_width >>= __ffs(GIC_CONFIG_COUNTBITS);
-	count_width *= 4;
-	count_width += 32;
-	gic_clocksource.mask = CLOCKSOURCE_MASK(count_width);
+	gic_count_width = read_gic_config() & GIC_CONFIG_COUNTBITS;
+	gic_count_width >>= __ffs(GIC_CONFIG_COUNTBITS);
+	gic_count_width *= 4;
+	gic_count_width += 32;
+	gic_clocksource.mask = CLOCKSOURCE_MASK(gic_count_width);
 
 	/* Calculate a somewhat reasonable rating value. */
-	gic_clocksource.rating = 200 + gic_frequency / 10000000;
+	if (mips_cm_revision() >= CM_REV_CM3 || !IS_ENABLED(CONFIG_CPU_FREQ))
+		gic_clocksource.rating = 300; /* Good when frequecy is stable */
+	else
+		gic_clocksource.rating = 200;
+	gic_clocksource.rating += clamp(gic_frequency / 10000000, 0, 99);
 
 	ret = clocksource_register_hz(&gic_clocksource, gic_frequency);
 	if (ret < 0)
@@ -260,7 +264,7 @@ static int __init gic_clocksource_of_init(struct device_node *node)
 	if (mips_cm_revision() >= CM_REV_CM3 || !IS_ENABLED(CONFIG_CPU_FREQ)) {
 		sched_clock_register(mips_cm_is64 ?
 				     gic_read_count_64 : gic_read_count_2x32,
-				     64, gic_frequency);
+				     gic_count_width, gic_frequency);
 	}
 
 	return 0;
diff --git a/drivers/clocksource/sh_cmt.c b/drivers/clocksource/sh_cmt.c
index 26919556ef5f..b72b36e0abed 100644
--- a/drivers/clocksource/sh_cmt.c
+++ b/drivers/clocksource/sh_cmt.c
@@ -528,6 +528,7 @@ static void sh_cmt_set_next(struct sh_cmt_channel *ch, unsigned long delta)
 static irqreturn_t sh_cmt_interrupt(int irq, void *dev_id)
 {
 	struct sh_cmt_channel *ch = dev_id;
+	unsigned long flags;
 
 	/* clear flags */
 	sh_cmt_write_cmcsr(ch, sh_cmt_read_cmcsr(ch) &
@@ -558,6 +559,8 @@ static irqreturn_t sh_cmt_interrupt(int irq, void *dev_id)
 
 	ch->flags &= ~FLAG_SKIPEVENT;
 
+	raw_spin_lock_irqsave(&ch->lock, flags);
+
 	if (ch->flags & FLAG_REPROGRAM) {
 		ch->flags &= ~FLAG_REPROGRAM;
 		sh_cmt_clock_event_program_verify(ch, 1);
@@ -570,6 +573,8 @@ static irqreturn_t sh_cmt_interrupt(int irq, void *dev_id)
 
 	ch->flags &= ~FLAG_IRQCONTEXT;
 
+	raw_spin_unlock_irqrestore(&ch->lock, flags);
+
 	return IRQ_HANDLED;
 }
 
@@ -780,12 +785,18 @@ static int sh_cmt_clock_event_next(unsigned long delta,
 				   struct clock_event_device *ced)
 {
 	struct sh_cmt_channel *ch = ced_to_sh_cmt(ced);
+	unsigned long flags;
 
 	BUG_ON(!clockevent_state_oneshot(ced));
+
+	raw_spin_lock_irqsave(&ch->lock, flags);
+
 	if (likely(ch->flags & FLAG_IRQCONTEXT))
 		ch->next_match_value = delta - 1;
 	else
-		sh_cmt_set_next(ch, delta - 1);
+		__sh_cmt_set_next(ch, delta - 1);
+
+	raw_spin_unlock_irqrestore(&ch->lock, flags);
 
 	return 0;
 }
diff --git a/drivers/clocksource/timer-rtl-otto.c b/drivers/clocksource/timer-rtl-otto.c
new file mode 100644
index 000000000000..8a3068b36e75
--- /dev/null
+++ b/drivers/clocksource/timer-rtl-otto.c
@@ -0,0 +1,291 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/cpu.h>
+#include <linux/cpuhotplug.h>
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/printk.h>
+#include <linux/sched_clock.h>
+#include "timer-of.h"
+
+#define RTTM_DATA		0x0
+#define RTTM_CNT		0x4
+#define RTTM_CTRL		0x8
+#define RTTM_INT		0xc
+
+#define RTTM_CTRL_ENABLE	BIT(28)
+#define RTTM_INT_PENDING	BIT(16)
+#define RTTM_INT_ENABLE		BIT(20)
+
+/*
+ * The Otto platform provides multiple 28 bit timers/counters with the following
+ * operating logic. If enabled the timer counts up. Per timer one can set a
+ * maximum counter value as an end marker. If end marker is reached the timer
+ * fires an interrupt. If the timer "overflows" by reaching the end marker or
+ * by adding 1 to 0x0fffffff the counter is reset to 0. When this happens and
+ * the timer is in operating mode COUNTER it stops. In mode TIMER it will
+ * continue to count up.
+ */
+#define RTTM_CTRL_COUNTER	0
+#define RTTM_CTRL_TIMER		BIT(24)
+
+#define RTTM_BIT_COUNT		28
+#define RTTM_MIN_DELTA		8
+#define RTTM_MAX_DELTA		CLOCKSOURCE_MASK(28)
+
+/*
+ * Timers are derived from the LXB clock frequency. Usually this is a fixed
+ * multiple of the 25 MHz oscillator. The 930X SOC is an exception from that.
+ * Its LXB clock has only dividers and uses the switch PLL of 2.45 GHz as its
+ * base. The only meaningful frequencies we can achieve from that are 175.000
+ * MHz and 153.125 MHz. The greatest common divisor of all explained possible
+ * speeds is 3125000. Pin the timers to this 3.125 MHz reference frequency.
+ */
+#define RTTM_TICKS_PER_SEC	3125000
+
+struct rttm_cs {
+	struct timer_of		to;
+	struct clocksource	cs;
+};
+
+/* Simple internal register functions */
+static inline void rttm_set_counter(void __iomem *base, unsigned int counter)
+{
+	iowrite32(counter, base + RTTM_CNT);
+}
+
+static inline unsigned int rttm_get_counter(void __iomem *base)
+{
+	return ioread32(base + RTTM_CNT);
+}
+
+static inline void rttm_set_period(void __iomem *base, unsigned int period)
+{
+	iowrite32(period, base + RTTM_DATA);
+}
+
+static inline void rttm_disable_timer(void __iomem *base)
+{
+	iowrite32(0, base + RTTM_CTRL);
+}
+
+static inline void rttm_enable_timer(void __iomem *base, u32 mode, u32 divisor)
+{
+	iowrite32(RTTM_CTRL_ENABLE | mode | divisor, base + RTTM_CTRL);
+}
+
+static inline void rttm_ack_irq(void __iomem *base)
+{
+	iowrite32(ioread32(base + RTTM_INT) | RTTM_INT_PENDING, base + RTTM_INT);
+}
+
+static inline void rttm_enable_irq(void __iomem *base)
+{
+	iowrite32(RTTM_INT_ENABLE, base + RTTM_INT);
+}
+
+static inline void rttm_disable_irq(void __iomem *base)
+{
+	iowrite32(0, base + RTTM_INT);
+}
+
+/* Aggregated control functions for kernel clock framework */
+#define RTTM_DEBUG(base)			\
+	pr_debug("------------- %d %p\n",	\
+		 smp_processor_id(), base)
+
+static irqreturn_t rttm_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *clkevt = dev_id;
+	struct timer_of *to = to_timer_of(clkevt);
+
+	rttm_ack_irq(to->of_base.base);
+	RTTM_DEBUG(to->of_base.base);
+	clkevt->event_handler(clkevt);
+
+	return IRQ_HANDLED;
+}
+
+static void rttm_stop_timer(void __iomem *base)
+{
+	rttm_disable_timer(base);
+	rttm_ack_irq(base);
+}
+
+static void rttm_start_timer(struct timer_of *to, u32 mode)
+{
+	rttm_set_counter(to->of_base.base, 0);
+	rttm_enable_timer(to->of_base.base, mode, to->of_clk.rate / RTTM_TICKS_PER_SEC);
+}
+
+static int rttm_next_event(unsigned long delta, struct clock_event_device *clkevt)
+{
+	struct timer_of *to = to_timer_of(clkevt);
+
+	RTTM_DEBUG(to->of_base.base);
+	rttm_stop_timer(to->of_base.base);
+	rttm_set_period(to->of_base.base, delta);
+	rttm_start_timer(to, RTTM_CTRL_COUNTER);
+
+	return 0;
+}
+
+static int rttm_state_oneshot(struct clock_event_device *clkevt)
+{
+	struct timer_of *to = to_timer_of(clkevt);
+
+	RTTM_DEBUG(to->of_base.base);
+	rttm_stop_timer(to->of_base.base);
+	rttm_set_period(to->of_base.base, RTTM_TICKS_PER_SEC / HZ);
+	rttm_start_timer(to, RTTM_CTRL_COUNTER);
+
+	return 0;
+}
+
+static int rttm_state_periodic(struct clock_event_device *clkevt)
+{
+	struct timer_of *to = to_timer_of(clkevt);
+
+	RTTM_DEBUG(to->of_base.base);
+	rttm_stop_timer(to->of_base.base);
+	rttm_set_period(to->of_base.base, RTTM_TICKS_PER_SEC / HZ);
+	rttm_start_timer(to, RTTM_CTRL_TIMER);
+
+	return 0;
+}
+
+static int rttm_state_shutdown(struct clock_event_device *clkevt)
+{
+	struct timer_of *to = to_timer_of(clkevt);
+
+	RTTM_DEBUG(to->of_base.base);
+	rttm_stop_timer(to->of_base.base);
+
+	return 0;
+}
+
+static void rttm_setup_timer(void __iomem *base)
+{
+	RTTM_DEBUG(base);
+	rttm_stop_timer(base);
+	rttm_set_period(base, 0);
+}
+
+static u64 rttm_read_clocksource(struct clocksource *cs)
+{
+	struct rttm_cs *rcs = container_of(cs, struct rttm_cs, cs);
+
+	return rttm_get_counter(rcs->to.of_base.base);
+}
+
+/* Module initialization part. */
+static DEFINE_PER_CPU(struct timer_of, rttm_to) = {
+	.flags				= TIMER_OF_BASE | TIMER_OF_CLOCK | TIMER_OF_IRQ,
+	.of_irq = {
+		.flags			= IRQF_PERCPU | IRQF_TIMER,
+		.handler		= rttm_timer_interrupt,
+	},
+	.clkevt = {
+		.rating			= 400,
+		.features		= CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
+		.set_state_periodic	= rttm_state_periodic,
+		.set_state_shutdown	= rttm_state_shutdown,
+		.set_state_oneshot	= rttm_state_oneshot,
+		.set_next_event		= rttm_next_event
+	},
+};
+
+static int rttm_enable_clocksource(struct clocksource *cs)
+{
+	struct rttm_cs *rcs = container_of(cs, struct rttm_cs, cs);
+
+	rttm_disable_irq(rcs->to.of_base.base);
+	rttm_setup_timer(rcs->to.of_base.base);
+	rttm_enable_timer(rcs->to.of_base.base, RTTM_CTRL_TIMER,
+			  rcs->to.of_clk.rate / RTTM_TICKS_PER_SEC);
+
+	return 0;
+}
+
+struct rttm_cs rttm_cs = {
+	.to = {
+		.flags	= TIMER_OF_BASE | TIMER_OF_CLOCK,
+	},
+	.cs = {
+		.name	= "realtek_otto_timer",
+		.rating	= 400,
+		.mask	= CLOCKSOURCE_MASK(RTTM_BIT_COUNT),
+		.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
+		.read	= rttm_read_clocksource,
+	}
+};
+
+static u64 notrace rttm_read_clock(void)
+{
+	return rttm_get_counter(rttm_cs.to.of_base.base);
+}
+
+static int rttm_cpu_starting(unsigned int cpu)
+{
+	struct timer_of *to = per_cpu_ptr(&rttm_to, cpu);
+
+	RTTM_DEBUG(to->of_base.base);
+	to->clkevt.cpumask = cpumask_of(cpu);
+	irq_force_affinity(to->of_irq.irq, to->clkevt.cpumask);
+	clockevents_config_and_register(&to->clkevt, RTTM_TICKS_PER_SEC,
+					RTTM_MIN_DELTA, RTTM_MAX_DELTA);
+	rttm_enable_irq(to->of_base.base);
+
+	return 0;