timer: Add High Precision Event Timers (HPET) support

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Add tsc_rate_mhz() function and use it in the code that specifically needs to get TSC rate regardless of currently selected early timer.

void delay_n(uint32_t ns)
{
/* 1000 MHz clock has 1ns period --> no conversion required
*/

arch/x86/cpu/quark/mrc_util.c +0 -1

-	uint64_t final_tsc = rdtsc();

Quoted 21 lines

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Add tsc_rate_mhz() function and use it in the code that specifically needs to get TSC rate regardless of currently selected early timer.

void delay_n(uint32_t ns)
{
/* 1000 MHz clock has 1ns period --> no conversion required
*/

arch/x86/cpu/quark/mrc_util.c +3 -5

-	uint64_t final_tsc = rdtsc();
+	uint64_t start_tsc = rdtsc();
+	uint64_t ticks;
 
-	final_tsc += ((get_tbclk_mhz() * ns) / 1000);
-
-	while (rdtsc() < final_tsc)
-		;
+	ticks = (tsc_rate_mhz() * ns) / 1000;

arch/x86/cpu/quark/mrc_util.c void mrc_post_code(uint8_t major, uint8_t minor) · line 64

Quoted 1 line

arch/x86/cpu/quark/mrc_util.c +1 -0

+	while (rdtsc() - start_tsc < ticks);

I would rather preserve existing style.

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Add tsc_rate_mhz() function and use it in the code that specifically needs to get TSC rate regardless of currently selected early timer.

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

---
 arch/x86/cpu/coreboot/timestamp.c |  2 +-
 arch/x86/cpu/quark/mrc_util.c     | 13 ++++++-------
 arch/x86/include/asm/u-boot-x86.h |  2 +-
 drivers/timer/tsc_timer.c         | 33 ++++++++++++++++++++++++---------
 4 files changed, 32 insertions(+), 18 deletions(-)

arch/x86/cpu/coreboot/timestamp.c +1 -1

index b382795..05bb214 100644
@@ -78,7 +78,7 @@ int timestamp_add_to_bootstage(void)
                if (name) {
                        bootstage_add_record(0, name, BOOTSTAGEF_ALLOC,
                                             tse->entry_stamp /
-                                                       get_tbclk_mhz());
+                                                       tsc_rate_mhz());
                }
        }
 

arch/x86/cpu/quark/mrc_util.c +6 -7

index fac2d72..4794395 100644
@@ -57,19 +57,18 @@ void mrc_post_code(uint8_t major, uint8_t minor)
 void delay_n(uint32_t ns)
 {
        /* 1000 MHz clock has 1ns period --> no conversion required */
-       uint64_t final_tsc = rdtsc();
+       uint64_t start_tsc = rdtsc();
+       uint64_t ticks;
 
-       final_tsc += ((get_tbclk_mhz() * ns) / 1000);
-
-       while (rdtsc() < final_tsc)
-               ;
+       ticks = (tsc_rate_mhz() * ns) / 1000;
+       while (rdtsc() - start_tsc < ticks);
 }
 
 /* Delay number of microseconds */
-void delay_u(uint32_t ms)
+void delay_u(uint32_t us)
 {
        /* 64-bit math is not an option, just use loops */
-       while (ms--)
+       while (us--)
                delay_n(1000);
 }
 

arch/x86/include/asm/u-boot-x86.h +1 -1

index 187fe5f..de68120 100644
@@ -29,7 +29,7 @@ int cleanup_before_linux(void);
 void timer_isr(void *);
 typedef void (timer_fnc_t) (void);
 int register_timer_isr (timer_fnc_t *isr_func);
-unsigned long get_tbclk_mhz(void);
+unsigned long tsc_rate_mhz(void);
 void timer_set_base(uint64_t base);
 int i8254_init(void);
 

drivers/timer/tsc_timer.c +18 -9

index 9296de6..98cbf12 100644
@@ -277,15 +277,12 @@ success:
        return delta / 1000;
 }
 
-/* Get the speed of the TSC timer in MHz */
-unsigned notrace long get_tbclk_mhz(void)
-{
-       return get_tbclk() / 1000000;
-}
-
 static ulong get_ms_timer(void)
 {
-       return (get_ticks() * 1000) / get_tbclk();
+       if (gd->arch.clock_rate == 0)
+               return 0;
+
+       return (rdtsc() * 1000) / gd->arch.clock_rate;
 }
 
 ulong get_timer(ulong base)

@@ -295,7 +292,10 @@ ulong get_timer(ulong base)
 
 ulong notrace timer_get_us(void)
 {
-       return get_ticks() / get_tbclk_mhz();
+       if (gd->arch.clock_rate == 0)
+               return 0;
+
+       return (rdtsc() * 1000000) / gd->arch.clock_rate;
 }
 
 ulong timer_get_boot_us(void)

@@ -308,7 +308,7 @@ void __udelay(unsigned long usec)
        u64 now = get_ticks();
        u64 stop;
 
-       stop = now + usec * get_tbclk_mhz();
+       stop = now + ((u64)usec * gd->arch.clock_rate) / 1000000;
 
        while ((int64_t)(stop - get_ticks()) > 0)
 #if defined(CONFIG_QEMU) && defined(CONFIG_SMP)

@@ -355,6 +355,14 @@ static void tsc_timer_ensure_setup(void)
        }
 }
 
+/* Get the speed of the TSC timer in MHz */
+unsigned notrace long tsc_rate_mhz(void)
+{
+       tsc_timer_ensure_setup();
+
+       return gd->arch.clock_rate / 1000000;
+}
+
 static int tsc_timer_probe(struct udevice *dev)
 {
        struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);

@@ -365,6 +373,13 @@ static int tsc_timer_probe(struct udevice *dev)
        return 0;
 }
 
+int timer_init(void)

Hi Ivan,

Quoted 4 lines · Ivan Gorinov

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Thanks for working on this. But get_tbclk() is one API provided by the timer library. The get_tbclk_mhz() is something that is implemented by the TSC timer driver, so can we get rid of the get_tbclk_mhz() and use the get_tbclk() instead in coreboot/timestamp.c and quark/mrc_util.c?

Quoted 6 lines · Andy Shevchenko

arch/x86/cpu/quark/mrc_util.c void mrc_post_code(uint8_t major, uint8_t minor)

Quoted 4 lines

arch/x86/cpu/quark/mrc_util.c +1 -2

-	while (rdtsc() < final_tsc)
-		;
 
+	while (rdtsc() - start_tsc < ticks);

I would rather preserve existing style.

OK. Existing style does not correctly handle overflow, but for a 64-bit counter it's a very unlikely event.

Quoted 3 lines

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Thanks for working on this. But get_tbclk() is one API provided by the timer library. The get_tbclk_mhz() is something that is implemented by the TSC timer driver, so can we get rid of the get_tbclk_mhz() and use the get_tbclk() instead in coreboot/timestamp.c and quark/mrc_util.c?

Quoted 142 lines

Add tsc_rate_mhz() function and use it in the code that specifically needs to get TSC rate regardless of currently selected early timer.

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

---
 arch/x86/cpu/coreboot/timestamp.c |  2 +-
 arch/x86/cpu/quark/mrc_util.c     | 13 ++++++-------
 arch/x86/include/asm/u-boot-x86.h |  2 +-
 drivers/timer/tsc_timer.c         | 33 ++++++++++++++++++++++++---------
 4 files changed, 32 insertions(+), 18 deletions(-)

arch/x86/cpu/coreboot/timestamp.c +1 -1

index b382795..05bb214 100644
@@ -78,7 +78,7 @@ int timestamp_add_to_bootstage(void)
                if (name) {
                        bootstage_add_record(0, name, BOOTSTAGEF_ALLOC,
                                             tse->entry_stamp /
-                                                       get_tbclk_mhz());
+                                                       tsc_rate_mhz());
                }
        }
 

arch/x86/cpu/quark/mrc_util.c +6 -7

index fac2d72..4794395 100644
@@ -57,19 +57,18 @@ void mrc_post_code(uint8_t major, uint8_t minor)
 void delay_n(uint32_t ns)
 {
        /* 1000 MHz clock has 1ns period --> no conversion required */
-       uint64_t final_tsc = rdtsc();
+       uint64_t start_tsc = rdtsc();
+       uint64_t ticks;
 
-       final_tsc += ((get_tbclk_mhz() * ns) / 1000);
-
-       while (rdtsc() < final_tsc)
-               ;
+       ticks = (tsc_rate_mhz() * ns) / 1000;
+       while (rdtsc() - start_tsc < ticks);
 }
 
 /* Delay number of microseconds */
-void delay_u(uint32_t ms)
+void delay_u(uint32_t us)
 {
        /* 64-bit math is not an option, just use loops */
-       while (ms--)
+       while (us--)
                delay_n(1000);
 }
 

arch/x86/include/asm/u-boot-x86.h +1 -1

index 187fe5f..de68120 100644
@@ -29,7 +29,7 @@ int cleanup_before_linux(void);
 void timer_isr(void *);
 typedef void (timer_fnc_t) (void);
 int register_timer_isr (timer_fnc_t *isr_func);
-unsigned long get_tbclk_mhz(void);
+unsigned long tsc_rate_mhz(void);
 void timer_set_base(uint64_t base);
 int i8254_init(void);
 

drivers/timer/tsc_timer.c +24 -10

index 9296de6..98cbf12 100644
@@ -277,15 +277,12 @@ success:
        return delta / 1000;
 }
 
-/* Get the speed of the TSC timer in MHz */
-unsigned notrace long get_tbclk_mhz(void)
-{
-       return get_tbclk() / 1000000;
-}
-
 static ulong get_ms_timer(void)
 {
-       return (get_ticks() * 1000) / get_tbclk();
+       if (gd->arch.clock_rate == 0)
+               return 0;
+
+       return (rdtsc() * 1000) / gd->arch.clock_rate;
 }
 
 ulong get_timer(ulong base)

@@ -295,7 +292,10 @@ ulong get_timer(ulong base)
 
 ulong notrace timer_get_us(void)
 {
-       return get_ticks() / get_tbclk_mhz();
+       if (gd->arch.clock_rate == 0)
+               return 0;
+
+       return (rdtsc() * 1000000) / gd->arch.clock_rate;
 }
 
 ulong timer_get_boot_us(void)

@@ -308,7 +308,7 @@ void __udelay(unsigned long usec)
        u64 now = get_ticks();
        u64 stop;
 
-       stop = now + usec * get_tbclk_mhz();
+       stop = now + ((u64)usec * gd->arch.clock_rate) / 1000000;
 
        while ((int64_t)(stop - get_ticks()) > 0)
 #if defined(CONFIG_QEMU) && defined(CONFIG_SMP)

@@ -355,6 +355,14 @@ static void tsc_timer_ensure_setup(void)
        }
 }
 
+/* Get the speed of the TSC timer in MHz */
+unsigned notrace long tsc_rate_mhz(void)
+{
+       tsc_timer_ensure_setup();
+
+       return gd->arch.clock_rate / 1000000;
+}
+
 static int tsc_timer_probe(struct udevice *dev)
 {
        struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);

@@ -365,6 +373,13 @@ static int tsc_timer_probe(struct udevice *dev)
        return 0;
 }
 
+int timer_init(void)
+{
+       tsc_timer_ensure_setup();
+
+       return 0;
+}
+
 unsigned long notrace timer_early_get_rate(void)
 {
        tsc_timer_ensure_setup();
--

Hi Bin,

Quoted 4 lines · Bin Meng

Quoted 3 lines

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Quoted 4 lines

Thanks for working on this. But get_tbclk() is one API provided by the timer library. The get_tbclk_mhz() is something that is implemented by the TSC timer driver, so can we get rid of the get_tbclk_mhz() and use the get_tbclk() instead in coreboot/timestamp.c and quark/mrc_util.c?

The Coreboot timestamp code and Quark MRC specifically use rdtsc(). We can replace it with timer_early_get_count() or provide a function to get the TSC frequency even when another early timer is selected.

Hi Ivan,

Quoted 12 lines · Ivan Gorinov

Hi Bin,

Quoted 8 lines · Bin Meng

Quoted 3 lines

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Thanks for working on this. But get_tbclk() is one API provided by the timer library. The get_tbclk_mhz() is something that is implemented by the TSC timer driver, so can we get rid of the get_tbclk_mhz() and use the get_tbclk() instead in coreboot/timestamp.c and quark/mrc_util.c?

Quoted 4 lines

The Coreboot timestamp code and Quark MRC specifically use rdtsc(). We can replace it with timer_early_get_count() or provide a function to get the TSC frequency even when another early timer is selected.

Good catch. Yes, we should fix coreboot timestamp code and Quark MRC codes to not explicitly call rdtsc.

Another driver that explicitly calls rdtsc() is hw_watchdog_reset() in watchdog/tangier_wdt.c driver. We need fix that too.

Hi Ivan,

Quoted 15 lines · Bin Meng

Hi Ivan,

Quoted 12 lines · Ivan Gorinov

Hi Bin,

Quoted 8 lines · Bin Meng

Quoted 3 lines

Coreboot timestamp functions and Quark memory reference code use get_tbclk() to get TSC frequency. This will not work if another early timer is selected.

Thanks for working on this. But get_tbclk() is one API provided by the timer library. The get_tbclk_mhz() is something that is implemented by the TSC timer driver, so can we get rid of the get_tbclk_mhz() and use the get_tbclk() instead in coreboot/timestamp.c and quark/mrc_util.c?

Quoted 8 lines

Quoted 4 lines

The Coreboot timestamp code and Quark MRC specifically use rdtsc(). We can replace it with timer_early_get_count() or provide a function to get the TSC frequency even when another early timer is selected.

Good catch. Yes, we should fix coreboot timestamp code and Quark MRC codes to not explicitly call rdtsc.

Further checking the coreboot timestamp codes, I think we may have to leave the coreboot timestamp codes as it is now.

We have the codes blow:
void timestamp_add_now(enum timestamp_id id)

{
    timestamp_add(id, rdtsc());
}

We cannot replace rdtsc() with timer_early_get_count(), because this timestamp_add_now() is called both before and after DM initialization. If the HPET is selected as the early timer and TSC is selected as the normal timer, the timestamp numbers are meaningless to compare against each other.

Quoted 3 lines

Another driver that explicitly calls rdtsc() is hw_watchdog_reset() in watchdog/tangier_wdt.c driver. We need fix that too.

Simon, another issue is the bootstage support. So far the timer_get_boot_us() is not implemented by DM timer APIs. timer_get_boot_us() is implemented per timer driver if CONFIG_SYS_TIMER_COUNTER is not defined. Note CONFIG_SYS_TIMER_COUNTER is non-DM stuff. That means the bootstage support is bounded by a specific timer driver, instead of a generic library. To me this overall timer support is somehow fragmentary.