armv8: Allow SoCs to override the generic timer

PATCH New Stephen Warren 5 participants 8 messages Jul 22, 2015 – Aug 2, 2015

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Arm (32-bit) Arm sub-architectures Tegra architecture support

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Stephen Warren

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2015-07-22 22:56 UTC #0 lore raw

PATCH 1/1 armv8: Allow SoCs to override the generic timer

From: Thierry Reding <[email protected]>

Some SoCs come with a custom timer interface, so allow them to use that instead.

swarren notes: I did consider reworking this patch so the Makefile only compiles generic_timer.c ifndef CONFIG_SYS_TIMER_COUNTER. However, I can foresee a time where generic_timer.c contains both routines to implement U-Boot's internal timer, and to perform other operations related to the generic timer, such as initializing the CNTFRQ register for a booted OS. If that happens, this version of the change will result in simpler future patches.

Signed-off-by Thierry Reding <[email protected]>

Signed-off-by Tom Warren <[email protected]>

Signed-off-by Stephen Warren <[email protected]>

---
 arch/arm/cpu/armv8/generic_timer.c | 2 ++
 1 file changed, 2 insertions(+)

arch/arm/cpu/armv8/generic_timer.c +2 -0

index 8e60baebc534..98a865cf6ffc 100644
@@ -9,6 +9,7 @@
 #include <command.h>
 #include <asm/system.h>
 
+#ifndef CONFIG_SYS_TIMER_COUNTER
 /*
  * Generic timer implementation of get_tbclk()
  */

@@ -40,3 +41,4 @@ unsigned long timer_read_counter(void)
 #endif
 	return cntpct;
 }
+#endif

Signature · 1 line

1.9.1

Simon Glass

2015-07-23 20:18 UTC #1 lore raw

PATCH 1/1 armv8: Allow SoCs to override the generic timer

Quoted 13 lines · Stephen Warren

From: Thierry Reding <[email protected]>
Some SoCs come with a custom timer interface, so allow them to use that instead.
swarren notes: I did consider reworking this patch so the Makefile only compiles generic_timer.c ifndef CONFIG_SYS_TIMER_COUNTER. However, I can foresee a time where generic_timer.c contains both routines to implement U-Boot's internal timer, and to perform other operations related to the generic timer, such as initializing the CNTFRQ register for a booted OS. If that happens, this version of the change will result in simpler future patches.

Quoted 6 lines

Signed-off-by Thierry Reding <[email protected]>
Signed-off-by Tom Warren <[email protected]>
Signed-off-by Stephen Warren <[email protected]>
---
 arch/arm/cpu/armv8/generic_timer.c | 2 ++
 1 file changed, 2 insertions(+)

Reviewed-by Simon Glass <[email protected]>

Tom Rini

2015-07-23 20:54 UTC #2 lore raw

PATCH 1/1 armv8: Allow SoCs to override the generic timer

In reply to Stephen Warren

Quoted 13 lines · Stephen Warren

From: Thierry Reding <[email protected]>
Some SoCs come with a custom timer interface, so allow them to use that instead.
swarren notes: I did consider reworking this patch so the Makefile only compiles generic_timer.c ifndef CONFIG_SYS_TIMER_COUNTER. However, I can foresee a time where generic_timer.c contains both routines to implement U-Boot's internal timer, and to perform other operations related to the generic timer, such as initializing the CNTFRQ register for a booted OS. If that happens, this version of the change will result in simpler future patches.

Quoted 3 lines

Signed-off-by Thierry Reding <[email protected]>
Signed-off-by Tom Warren <[email protected]>
Signed-off-by Stephen Warren <[email protected]>

Reviewed-by Tom Rini <[email protected]>

Quoted 3 lines

Signature · 1 line
1.9.1

Signature · 8 lines

Tom
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Thierry Reding

2015-07-28 09:33 UTC #3 lore raw

PATCH 1/1 armv8: Allow SoCs to override the generic timer

In reply to Stephen Warren

Quoted 13 lines · Stephen Warren

From: Thierry Reding <[email protected]>
Some SoCs come with a custom timer interface, so allow them to use that instead.
swarren notes: I did consider reworking this patch so the Makefile only compiles generic_timer.c ifndef CONFIG_SYS_TIMER_COUNTER. However, I can foresee a time where generic_timer.c contains both routines to implement U-Boot's internal timer, and to perform other operations related to the generic timer, such as initializing the CNTFRQ register for a booted OS. If that happens, this version of the change will result in simpler future patches.

Quoted 6 lines

Signed-off-by Thierry Reding <[email protected]>
Signed-off-by Tom Warren <[email protected]>
Signed-off-by Stephen Warren <[email protected]>
---
 arch/arm/cpu/armv8/generic_timer.c | 2 ++
 1 file changed, 2 insertions(+)

Marc Zyngier and David Feng had objections to this when I posted[0]. I ended up solving this differently, by initializing the architectural timer earlier and then using the architected timer on ARM64.

I'll post the two patches I have in my tree as a replacement for this and sorry for causing such a mess.

Thierry

[0]: http://lists.denx.de/pipermail/u-boot/2015-March/208505.html
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Thierry Reding

2015-07-28 09:35 UTC #4 lore raw

PATCH 1/2 ARM: tegra: Initialize timer earlier

In reply to Stephen Warren

From: Thierry Reding <[email protected]>

A subsequent patch will enable the use of the architected timer on ARMv8. Doing so implies that udelay() will be backed by this timer implementation, and hence the architected timer must be ready when udelay() is first called. The first time udelay() is used is while resetting the debug UART, which happens very early. Make sure that arch_timer_init() is called before that.

Signed-off-by Thierry Reding <[email protected]>

---
 arch/arm/mach-tegra/board2.c | 6 ++++++
 arch/arm/mach-tegra/clock.c  | 6 ------
 2 files changed, 6 insertions(+), 6 deletions(-)

arch/arm/mach-tegra/board2.c +6 -0

index 82a8a3c08959..f76fcbec5a7d 100644
@@ -218,6 +218,12 @@ void gpio_early_init(void) __attribute__((weak, alias("__gpio_early_init")));
 
 int board_early_init_f(void)
 {
+	/* Do any special system timer/TSC setup */
+#if defined(CONFIG_TEGRA_SUPPORT_NON_SECURE)
+	if (!tegra_cpu_is_non_secure())
+#endif
+		arch_timer_init();
+
 	pinmux_init();
 	board_init_uart_f();

arch/arm/mach-tegra/clock.c +0 -6

index 0e0f7431b2fb..551ce88960e3 100644
@@ -618,12 +618,6 @@ void clock_init(void)
 	debug("PLLC = %d\n", pll_rate[CLOCK_ID_CGENERAL]);
 	debug("PLLD = %d\n", pll_rate[CLOCK_ID_DISPLAY]);
 	debug("PLLX = %d\n", pll_rate[CLOCK_ID_XCPU]);
-
-	/* Do any special system timer/TSC setup */
-#if defined(CONFIG_TEGRA_SUPPORT_NON_SECURE)
-	if (!tegra_cpu_is_non_secure())
-#endif
-		arch_timer_init();
 }
 
 static void set_avp_clock_source(u32 src)

Signature · 1 line

2.4.5

Thierry Reding

2015-07-28 09:35 UTC #5 lore raw

PATCH 2/2 ARM: tegra: Use architected timer on ARMv8

From: Thierry Reding <[email protected]>

ARMv8 requires an architected timer to be present, so it can be used instead of the Tegra US timer. This allows for better code reuse.

Signed-off-by Thierry Reding <[email protected]>

---
 include/configs/tegra-common.h | 3 +++
 1 file changed, 3 insertions(+)

include/configs/tegra-common.h +3 -0

index 7b4c0d70636e..62b047115343 100644
@@ -18,8 +18,11 @@
 
 #include <asm/arch/tegra.h>		/* get chip and board defs */
 
+/* Use the Tegra US timer on ARMv7, but the architected timer on ARMv8. */
+#ifndef CONFIG_ARM64
 #define CONFIG_SYS_TIMER_RATE		1000000
 #define CONFIG_SYS_TIMER_COUNTER	NV_PA_TMRUS_BASE
+#endif
 
 /*
  * Display CPU and Board information

Signature · 1 line

2.4.5

Simon Glass

2015-08-02 21:29 UTC #6 lore raw

PATCH 2/2 ARM: tegra: Use architected timer on ARMv8

Hi Thierry,

Quoted 27 lines · Thierry Reding

From: Thierry Reding <[email protected]>
ARMv8 requires an architected timer to be present, so it can be used instead of the Tegra US timer. This allows for better code reuse.
Signed-off-by Thierry Reding <[email protected]>
---
 include/configs/tegra-common.h | 3 +++
 1 file changed, 3 insertions(+)
include/configs/tegra-common.h +3 -1
index 7b4c0d70636e..62b047115343 100644
@@ -18,8 +18,11 @@
 
 #include <asm/arch/tegra.h>            /* get chip and board defs */
 
+/* Use the Tegra US timer on ARMv7, but the architected timer on ARMv8. */
+#ifndef CONFIG_ARM64
 #define CONFIG_SYS_TIMER_RATE          1000000
 #define CONFIG_SYS_TIMER_COUNTER       NV_PA_TMRUS_BASE
+#endif
 
 /*
  * Display CPU and Board information
--

Quoted 2 lines

2.4.5

Shouldn't this go in tegra210-common.h or similar?

Regards,
Simon

Stephen Warren

author

2015-07-28 16:08 UTC #7 lore raw

PATCH 1/2 ARM: tegra: Initialize timer earlier

In reply to Thierry Reding

Quoted 8 lines · Thierry Reding

From: Thierry Reding <[email protected]>
A subsequent patch will enable the use of the architected timer on ARMv8. Doing so implies that udelay() will be backed by this timer implementation, and hence the architected timer must be ready when udelay() is first called. The first time udelay() is used is while resetting the debug UART, which happens very early. Make sure that arch_timer_init() is called before that.

The series,

Acked-by Stephen Warren <[email protected]>

Again I've tested these in the context of a downstream/L4T version of U-Boot and they worked out fine. However since I haven't tested the exact upstream code-base, I won't give a Tested-by tag.