timer: Add High Precision Event Timers (HPET) support

PATCH Superseded Ivan Gorinov 2 participants 3 messages Mar 31, 2018 x86

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Ivan Gorinov

author

2018-03-31 01:47 UTC #0 lore raw

PATCH v3 1/1 timer: Add High Precision Event Timers (HPET) support

Add HPET driver as an alternative timer for x86 (default is TSC). HPET counter has constant frequency and does not need calibration. This change also makes TSC timer driver optional on x86. New HPET driver can also be selected as the early timer on x86.

v3:
Added early timer choice in x86-specific configuration.

v2:
Moved duplicated code to static functions.

Ivan Gorinov (1):
timer: Add High Precision Event Timers (HPET) support

 arch/Kconfig               |   2 +-
 arch/x86/Kconfig           |  21 +++++
 arch/x86/dts/hpet.dtsi     |   7 ++
 drivers/timer/Kconfig      |   9 +++
 drivers/timer/Makefile     |   1 +
 drivers/timer/hpet_timer.c | 190 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/timer/tsc_timer.c  |   8 ++
 7 files changed, 237 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/dts/hpet.dtsi
 create mode 100644 drivers/timer/hpet_timer.c

Signature · 1 line

2.7.4

Ivan Gorinov

author

2018-03-31 01:47 UTC #1 lore raw

PATCH v3 1/1 timer: Add High Precision Event Timers (HPET) support

HPET can be selected as the tick timer in the Device Tree "chosen" node:

/include/ "hpet.dtsi"

...

    chosen {
        tick-timer = "/hpet";
    };

Signed-off-by Ivan Gorinov <[email protected]>

---
 arch/Kconfig               |   2 +-
 arch/x86/Kconfig           |  21 +++++
 arch/x86/dts/hpet.dtsi     |   7 ++
 drivers/timer/Kconfig      |   9 +++
 drivers/timer/Makefile     |   1 +
 drivers/timer/hpet_timer.c | 190 +++++++++++++++++++++++++++++++++++++++++++++
 drivers/timer/tsc_timer.c  |   8 ++
 7 files changed, 237 insertions(+), 1 deletion(-)
 create mode 100644 arch/x86/dts/hpet.dtsi
 create mode 100644 drivers/timer/hpet_timer.c

arch/Kconfig +1 -1

index e599e7a..37dabae 100644
@@ -104,7 +104,7 @@ config X86
 	select DM_PCI
 	select PCI
 	select TIMER
-	select X86_TSC_TIMER
+	imply X86_TSC_TIMER
 	imply BLK
 	imply DM_ETH
 	imply DM_GPIO

arch/x86/Kconfig +21 -0

index 5c23b2c..bd1a644 100644
@@ -119,6 +119,27 @@ source "arch/x86/cpu/tangier/Kconfig"
 
 # architecture-specific options below
 
+choice
+	prompt "Select which timer to use early on x86"
+	depends on X86
+	default X86_EARLY_TIMER_TSC
+
+config X86_EARLY_TIMER_TSC
+	bool "TSC"
+	depends on X86_TSC_TIMER
+	help
+	  This selects x86 Time Stamp Counter (TSC) as the early timer.
+	  See CONFIG_TIMER_EARLY for the early timer description.
+
+config X86_EARLY_TIMER_HPET
+	bool "HPET"
+	depends on HPET_TIMER
+	help
+	  This selects High Precision Event Timers as the early timer.
+	  Early HPET base address is specified by CONFIG_HPET_ADDRESS.
+
+endchoice
+
 config AHCI
 	default y

arch/x86/dts/hpet.dtsi new file +7 -0

new file mode 100644
index 0000000..a74f739
@@ -0,0 +1,7 @@
+/ {
+	hpet: hpet at fed00000 {
+		compatible = "hpet-x86";
+		u-boot,dm-pre-reloc;
+		reg = <0xfed00000 0x1000>;
+	};
+};

drivers/timer/Kconfig +9 -0

index 2c96896..26743b7 100644
@@ -65,6 +65,15 @@ config X86_TSC_TIMER
 	help
 	  Select this to enable Time-Stamp Counter (TSC) timer for x86.
 
+config HPET_TIMER
+	bool "High Precision Event Timers (HPET) support"
+	depends on TIMER
+	default y if X86
+	help
+	  Select this to enable High Precision Event Timers (HPET) on x86.
+	  HPET main counter increments at constant rate and does not need
+	  calibration.
+
 config OMAP_TIMER
 	bool "Omap timer support"
 	depends on TIMER

drivers/timer/Makefile +1 -0

index a6e7832..557fecc 100644
@@ -8,6 +8,7 @@ obj-y += timer-uclass.o
 obj-$(CONFIG_ALTERA_TIMER)	+= altera_timer.o
 obj-$(CONFIG_SANDBOX_TIMER)	+= sandbox_timer.o
 obj-$(CONFIG_X86_TSC_TIMER)	+= tsc_timer.o
+obj-$(CONFIG_HPET_TIMER)	+= hpet_timer.o
 obj-$(CONFIG_OMAP_TIMER)	+= omap-timer.o
 obj-$(CONFIG_AST_TIMER)	+= ast_timer.o
 obj-$(CONFIG_STI_TIMER)		+= sti-timer.o

drivers/timer/hpet_timer.c new file +190 -0

190 lines not on this page · raw message

drivers/timer/tsc_timer.c +8 -0

index 9296de6..bd0e75c 100644
@@ -277,6 +277,8 @@ success:
 	return delta / 1000;
 }
 
+#ifdef CONFIG_X86_EARLY_TIMER_TSC
+
 /* Get the speed of the TSC timer in MHz */
 unsigned notrace long get_tbclk_mhz(void)
 {

@@ -322,6 +324,8 @@ void __udelay(unsigned long usec)
 #endif
 }
 
+#endif /* CONFIG_X86_EARLY_TIMER_TSC */
+
 static int tsc_timer_get_count(struct udevice *dev, u64 *count)
 {
 	u64 now_tick = rdtsc();

@@ -365,6 +369,8 @@ static int tsc_timer_probe(struct udevice *dev)
 	return 0;
 }
 
+#ifdef CONFIG_X86_EARLY_TIMER_TSC
+
 unsigned long notrace timer_early_get_rate(void)
 {
 	tsc_timer_ensure_setup();

@@ -377,6 +383,8 @@ u64 notrace timer_early_get_count(void)
 	return rdtsc() - gd->arch.tsc_base;
 }
 
+#endif
+
 static const struct timer_ops tsc_timer_ops = {
 	.get_count = tsc_timer_get_count,
 };

Signature · 1 line

2.7.4

Andy Shevchenko

2018-03-31 12:33 UTC #2 lore raw

PATCH v3 1/1 timer: Add High Precision Event Timers (HPET) support

Quoted 4 lines · Ivan Gorinov

Add HPET driver as an alternative timer for x86 (default is TSC). HPET counter has constant frequency and does not need calibration. This change also makes TSC timer driver optional on x86. New HPET driver can also be selected as the early timer on x86.

You are too fast to produce new versions.

Same comments about 64-bit I/O accessors are applied here.

Also, please include x86 maintainers (get_maintainer script helps).

Signature · 2 lines

With Best Regards,
Andy Shevchenko