timer: Add High Precision Event Timers (HPET) support
PATCH v4 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.
v4:
Using 64-bit pointer for main counter access.
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 | 181 +++++++++++++++++++++++++++++++++++++++++++++ drivers/timer/tsc_timer.c | 8 ++ 7 files changed, 228 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
PATCH v4 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.
HPET can be selected as the tick timer in the Device Tree "chosen" node:
/include/ "hpet.dtsi"
...
chosen {
tick-timer = "/hpet";
};--- 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 | 181 +++++++++++++++++++++++++++++++++++++++++++++ drivers/timer/tsc_timer.c | 8 ++ 7 files changed, 228 insertions(+), 1 deletion(-) create mode 100644 arch/x86/dts/hpet.dtsi create mode 100644 drivers/timer/hpet_timer.c
arch/Kconfig +1 -1
@@ -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
@@ -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
@@ -0,0 +1,7 @@ +/ { + hpet: hpet at fed00000 { + compatible = "hpet-x86"; + u-boot,dm-pre-reloc; + reg = <0xfed00000 0x1000>; + }; +};
drivers/timer/Kconfig +9 -0
@@ -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
@@ -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 +181 -0
181 lines not on this page · raw message
drivers/timer/tsc_timer.c +8 -0
@@ -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
PATCH v4 1/1 timer: Add High Precision Event Timers (HPET) support
Quoted 6 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.
drivers/timer/hpet_timer.c new file +1
-0+/* Reset and start the main counter. */
drivers/timer/hpet_timer.c line 57
Quoted 10 lines
drivers/timer/hpet_timer.c new file +9
-0+static void start_main_counter (void *regs) +{ +volatile u64 *main_counter = regs +HPET_MAIN_COUNT ; +u32 config; + + config =readl (regs +HPET_CONFIG_REG ); + config &= ~ENABLE_CNF ; +writel (config, regs +HPET_CONFIG_REG ); + *main_counter =0 ;
It needs to be done as writeq() / readq().
Please, define them first in arch/x86/include/asm/io.h (as an example you can use arch/arm/include/asm/io.h).
Quoted 5 lines
drivers/timer/hpet_timer.c new file +5
-0+ config |=ENABLE_CNF ; +writel (config, regs +HPET_CONFIG_REG ); +} + +/* Read the main counter, repeat if 32-bit rollover happens. */
drivers/timer/hpet_timer.c line 71
Quoted 10 lines
drivers/timer/hpet_timer.c new file +9
-0+static u64 read_main_counter (void *regs) +{ +volatile u64 *main_counter = regs +HPET_MAIN_COUNT ; +u64 t, t0; + + t = *main_counter; + do { + t0 = t; + t = *main_counter;
Ditto.
Quoted 4 lines
drivers/timer/hpet_timer.c new file +4
-0+ }while ((t >>32 ) != (t0 >>32 )); + +return t; +}
Signature · 2 lines
Andy Shevchenko <[email protected]> Intel Finland Oy