[U-Boot] [PATCH 1/6] x86: tsc: Read all ratio bits from MSR_PLATFORM_INFO

[U-Boot] [PATCH 1/6] x86: tsc: Read all ratio bits from MSR_PLATFORM_INFO

[Bin Meng]

Currently we read the tsc radio like this:

	ratio = (MSR_PLATFORM_INFO >> 8) & 0x1f;

Thus we get bit 8-12 of MSR_PLATFORM_INFO, however according to the
Intel manual, the ratio bits are bit 8-15.

Fix this problem by masking 0xff instead.

This keeps in sync with Linux kernel commit:
  886123f: x86/tsc: Read all ratio bits from MSR_PLATFORM_INFO

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

 drivers/timer/tsc_timer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index 5c4ec00..ffbc709 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -92,7 +92,7 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
 
 	if (freq_desc_tables[cpu_index].msr_plat) {
 		rdmsr(MSR_PLATFORM_INFO, lo, hi);
-		ratio = (lo >> 8) & 0x1f;
+		ratio = (lo >> 8) & 0xff;
 	} else {
 		rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
 		ratio = (hi >> 8) & 0x1f;
-- 
2.9.2

[U-Boot] [PATCH 2/6] x86: tsc: Identify Intel-specific code

[Bin Meng]

cpu_mhz_from_msr() is currently Intel-specific, and should not
execute on any other vendor's parts.

This keeps in sync with Linux kernel commit:
  ba82683: x86/tsc_msr: Identify Intel-specific code

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

 drivers/timer/tsc_timer.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index ffbc709..4d01c9b 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -11,6 +11,7 @@
 #include <dm.h>
 #include <malloc.h>
 #include <timer.h>
+#include <asm/cpu.h>
 #include <asm/io.h>
 #include <asm/i8254.h>
 #include <asm/ibmpc.h>
@@ -86,6 +87,9 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
 	unsigned long res;
 	int cpu_index;
 
+	if (gd->arch.x86_vendor != X86_VENDOR_INTEL)
+		return 0;
+
 	cpu_index = match_cpu(gd->arch.x86, gd->arch.x86_model);
 	if (cpu_index < 0)
 		return 0;
-- 
2.9.2

[U-Boot] [PATCH 2/6] x86: tsc: Identify Intel-specific code

[Bin Meng]

On Wed, Jul 26, 2017 at 11:12 AM, Bin Meng <bmeng.cn@gmail.com> wrote:
> cpu_mhz_from_msr() is currently Intel-specific, and should not

oops: patch ordering issue :)

It should be: try_msr_calibrate_tsc()... as try_msr_calibrate_tsc() is
renamed to cpu_mhz_from_msr() in patch [6/6]

> execute on any other vendor's parts.
>
> This keeps in sync with Linux kernel commit:
>   ba82683: x86/tsc_msr: Identify Intel-specific code
>
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>
>  drivers/timer/tsc_timer.c | 4 ++++
>  1 file changed, 4 insertions(+)

Regards,
Bin

[U-Boot] [PATCH 2/6] x86: tsc: Identify Intel-specific code

[Simon Glass]

On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
> cpu_mhz_from_msr() is currently Intel-specific, and should not
> execute on any other vendor's parts.
>
> This keeps in sync with Linux kernel commit:
>   ba82683: x86/tsc_msr: Identify Intel-specific code
>
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>
>  drivers/timer/tsc_timer.c | 4 ++++
>  1 file changed, 4 insertions(+)

Reviewed-by: Simon Glass <sjg@chromium.org>

[U-Boot] [PATCH 2/6] x86: tsc: Identify Intel-specific code

[Bin Meng]

On Tue, Aug 1, 2017 at 5:11 PM, Simon Glass <sjg@chromium.org> wrote:
> On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
>> cpu_mhz_from_msr() is currently Intel-specific, and should not

Fixed the commit message, and

>> execute on any other vendor's parts.
>>
>> This keeps in sync with Linux kernel commit:
>>   ba82683: x86/tsc_msr: Identify Intel-specific code
>>
>> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
>> ---
>>
>>  drivers/timer/tsc_timer.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>
> Reviewed-by: Simon Glass <sjg@chromium.org>

applied to u-boot-x86, thanks!

[U-Boot] [PATCH 3/6] x86: tsc: Remove the fail handling in try_msr_calibrate_tsc()

[Bin Meng]

If either ratio or freq is zero, the return value is zero. There
is no need to create a fail branch and return zero there.

This keeps in sync with Linux kernel commit:
  14bb4e3: x86/tsc_msr: Remove debugging messages

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

 drivers/timer/tsc_timer.c | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index 4d01c9b..bdbecac 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -103,9 +103,6 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
 	}
 	debug("Maximum core-clock to bus-clock ratio: 0x%x\n", ratio);
 
-	if (!ratio)
-		goto fail;
-
 	if (freq_desc_tables[cpu_index].msr_plat == 2) {
 		/* TODO: Figure out how best to deal with this */
 		freq = FREQ_100;
@@ -118,18 +115,12 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
 		debug("Resolved frequency ID: %u, frequency: %u KHz\n",
 		      freq_id, freq);
 	}
-	if (!freq)
-		goto fail;
 
 	/* TSC frequency = maximum resolved freq * maximum resolved bus ratio */
 	res = freq * ratio / 1000;
 	debug("TSC runs at %lu MHz\n", res);
 
 	return res;
-
-fail:
-	debug("Fast TSC calibration using MSR failed\n");
-	return 0;
 }
 
 /*
-- 
2.9.2

[U-Boot] [PATCH 3/6] x86: tsc: Remove the fail handling in try_msr_calibrate_tsc()

[Simon Glass]

On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
> If either ratio or freq is zero, the return value is zero. There
> is no need to create a fail branch and return zero there.
>
> This keeps in sync with Linux kernel commit:
>   14bb4e3: x86/tsc_msr: Remove debugging messages
>
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>
>  drivers/timer/tsc_timer.c | 9 ---------
>  1 file changed, 9 deletions(-)

Reviewed-by: Simon Glass <sjg@chromium.org>

[U-Boot] [PATCH 3/6] x86: tsc: Remove the fail handling in try_msr_calibrate_tsc()

[Bin Meng]

On Tue, Aug 1, 2017 at 5:11 PM, Simon Glass <sjg@chromium.org> wrote:
> On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
>> If either ratio or freq is zero, the return value is zero. There
>> is no need to create a fail branch and return zero there.
>>
>> This keeps in sync with Linux kernel commit:
>>   14bb4e3: x86/tsc_msr: Remove debugging messages
>>
>> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
>> ---
>>
>>  drivers/timer/tsc_timer.c | 9 ---------
>>  1 file changed, 9 deletions(-)
>
> Reviewed-by: Simon Glass <sjg@chromium.org>

applied to u-boot-x86, thanks!

[U-Boot] [PATCH 4/6] x86: tsc: Update comments and expand definitions in freq_desc_tables[]

[Bin Meng]

Some processor abbreviations in the comments of freq_desc_tables[]
are obscure. This updates part of these to mention processors
that are known to us. Also expand frequency definitions.

This keeps in sync with Linux kernel commit:
  9e0cae9: x86/tsc_msr: Update comments, expand definitions

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

 drivers/timer/tsc_timer.c | 24 +++++++++---------------
 1 file changed, 9 insertions(+), 15 deletions(-)

diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index bdbecac..3c1b745 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -18,12 +18,6 @@
 #include <asm/msr.h>
 #include <asm/u-boot-x86.h>
 
-/* CPU reference clock frequency: in KHz */
-#define FREQ_83		83200
-#define FREQ_100	99840
-#define FREQ_133	133200
-#define FREQ_166	166400
-
 #define MAX_NUM_FREQS	8
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -46,17 +40,17 @@ struct freq_desc {
 
 static struct freq_desc freq_desc_tables[] = {
 	/* PNW */
-	{ 6, 0x27, 0, { 0, 0, 0, 0, 0, FREQ_100, 0, FREQ_83 } },
+	{ 6, 0x27, 0, { 0, 0, 0, 0, 0, 99840, 0, 83200 } },
 	/* CLV+ */
-	{ 6, 0x35, 0, { 0, FREQ_133, 0, 0, 0, FREQ_100, 0, FREQ_83 } },
-	/* TNG */
-	{ 6, 0x4a, 1, { 0, FREQ_100, FREQ_133, 0, 0, 0, 0, 0 } },
-	/* VLV2 */
-	{ 6, 0x37, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_166, 0, 0, 0, 0 } },
+	{ 6, 0x35, 0, { 0, 133200, 0, 0, 0, 99840, 0, 83200 } },
+	/* TNG - Intel Atom processor Z3400 series */
+	{ 6, 0x4a, 1, { 0, 99840, 133200, 0, 0, 0, 0, 0 } },
+	/* VLV2 - Intel Atom processor E3000, Z3600, Z3700 series */
+	{ 6, 0x37, 1, { 83200, 99840, 133200, 166400, 0, 0, 0, 0 } },
+	/* ANN - Intel Atom processor Z3500 series */
+	{ 6, 0x5a, 1, { 83200, 99840, 133200, 99840, 0, 0, 0, 0 } },
 	/* Ivybridge */
 	{ 6, 0x3a, 2, { 0, 0, 0, 0, 0, 0, 0, 0 } },
-	/* ANN */
-	{ 6, 0x5a, 1, { FREQ_83, FREQ_100, FREQ_133, FREQ_100, 0, 0, 0, 0 } },
 };
 
 static int match_cpu(u8 family, u8 model)
@@ -105,7 +99,7 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
 
 	if (freq_desc_tables[cpu_index].msr_plat == 2) {
 		/* TODO: Figure out how best to deal with this */
-		freq = FREQ_100;
+		freq = 99840;
 		debug("Using frequency: %u KHz\n", freq);
 	} else {
 		/* Get FSB FREQ ID */
-- 
2.9.2

[U-Boot] [PATCH 4/6] x86: tsc: Update comments and expand definitions in freq_desc_tables[]

[Simon Glass]

On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
> Some processor abbreviations in the comments of freq_desc_tables[]
> are obscure. This updates part of these to mention processors
> that are known to us. Also expand frequency definitions.
>
> This keeps in sync with Linux kernel commit:
>   9e0cae9: x86/tsc_msr: Update comments, expand definitions
>
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>
>  drivers/timer/tsc_timer.c | 24 +++++++++---------------
>  1 file changed, 9 insertions(+), 15 deletions(-)

Reviewed-by: Simon Glass <sjg@chromium.org>

[U-Boot] [PATCH 4/6] x86: tsc: Update comments and expand definitions in freq_desc_tables[]

[Bin Meng]

On Tue, Aug 1, 2017 at 5:11 PM, Simon Glass <sjg@chromium.org> wrote:
> On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
>> Some processor abbreviations in the comments of freq_desc_tables[]
>> are obscure. This updates part of these to mention processors
>> that are known to us. Also expand frequency definitions.
>>
>> This keeps in sync with Linux kernel commit:
>>   9e0cae9: x86/tsc_msr: Update comments, expand definitions
>>
>> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
>> ---
>>
>>  drivers/timer/tsc_timer.c | 24 +++++++++---------------
>>  1 file changed, 9 insertions(+), 15 deletions(-)
>
> Reviewed-by: Simon Glass <sjg@chromium.org>

applied to u-boot-x86, thanks!

[U-Boot] [PATCH 5/6] x86: tsc: Correct Silvermont reference clock values

[Bin Meng]

Atom processors use a 19.2 MHz crystal oscillator.

Early processors generate 100 MHz via 19.2 MHz * 26 / 5 = 99.84 MHz.

Later processors generate 100 MHz via 19.2 MHz * 125 / 24 = 100 MHz.

Update the Silvermont-based tables accordingly, matching the Software
Developers Manual.

Also, correct a 166 MHz entry that should have been 116 MHz, and add
a missing 80 MHz entry for VLV2.

This keeps in sync with Linux kernel commit:
  05680e7: x86/tsc_msr: Correct Silvermont reference clock values

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

 drivers/timer/tsc_timer.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index 3c1b745..b242e74 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -44,11 +44,11 @@ static struct freq_desc freq_desc_tables[] = {
 	/* CLV+ */
 	{ 6, 0x35, 0, { 0, 133200, 0, 0, 0, 99840, 0, 83200 } },
 	/* TNG - Intel Atom processor Z3400 series */
-	{ 6, 0x4a, 1, { 0, 99840, 133200, 0, 0, 0, 0, 0 } },
+	{ 6, 0x4a, 1, { 0, 100000, 133300, 0, 0, 0, 0, 0 } },
 	/* VLV2 - Intel Atom processor E3000, Z3600, Z3700 series */
-	{ 6, 0x37, 1, { 83200, 99840, 133200, 166400, 0, 0, 0, 0 } },
+	{ 6, 0x37, 1, { 83300, 100000, 133300, 116700, 80000, 0, 0, 0 } },
 	/* ANN - Intel Atom processor Z3500 series */
-	{ 6, 0x5a, 1, { 83200, 99840, 133200, 99840, 0, 0, 0, 0 } },
+	{ 6, 0x5a, 1, { 83300, 100000, 133300, 100000, 0, 0, 0, 0 } },
 	/* Ivybridge */
 	{ 6, 0x3a, 2, { 0, 0, 0, 0, 0, 0, 0, 0 } },
 };
@@ -99,7 +99,7 @@ static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
 
 	if (freq_desc_tables[cpu_index].msr_plat == 2) {
 		/* TODO: Figure out how best to deal with this */
-		freq = 99840;
+		freq = 100000;
 		debug("Using frequency: %u KHz\n", freq);
 	} else {
 		/* Get FSB FREQ ID */
-- 
2.9.2

[U-Boot] [PATCH 5/6] x86: tsc: Correct Silvermont reference clock values

[Simon Glass]

On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
> Atom processors use a 19.2 MHz crystal oscillator.
>
> Early processors generate 100 MHz via 19.2 MHz * 26 / 5 = 99.84 MHz.
>
> Later processors generate 100 MHz via 19.2 MHz * 125 / 24 = 100 MHz.
>
> Update the Silvermont-based tables accordingly, matching the Software
> Developers Manual.
>
> Also, correct a 166 MHz entry that should have been 116 MHz, and add
> a missing 80 MHz entry for VLV2.
>
> This keeps in sync with Linux kernel commit:
>   05680e7: x86/tsc_msr: Correct Silvermont reference clock values
>
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>
>  drivers/timer/tsc_timer.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
>

Reviewed-by: Simon Glass <sjg@chromium.org>

[U-Boot] [PATCH 5/6] x86: tsc: Correct Silvermont reference clock values

[Bin Meng]

On Tue, Aug 1, 2017 at 5:11 PM, Simon Glass <sjg@chromium.org> wrote:
> On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
>> Atom processors use a 19.2 MHz crystal oscillator.
>>
>> Early processors generate 100 MHz via 19.2 MHz * 26 / 5 = 99.84 MHz.
>>
>> Later processors generate 100 MHz via 19.2 MHz * 125 / 24 = 100 MHz.
>>
>> Update the Silvermont-based tables accordingly, matching the Software
>> Developers Manual.
>>
>> Also, correct a 166 MHz entry that should have been 116 MHz, and add
>> a missing 80 MHz entry for VLV2.
>>
>> This keeps in sync with Linux kernel commit:
>>   05680e7: x86/tsc_msr: Correct Silvermont reference clock values
>>
>> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
>> ---
>>
>>  drivers/timer/tsc_timer.c | 8 ++++----
>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>
>
> Reviewed-by: Simon Glass <sjg@chromium.org>

applied to u-boot-x86, thanks!

[U-Boot] [PATCH 6/6] x86: tsc: Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr()

[Bin Meng]

Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr(), as that
better describes what the routine does.

This keeps in sync with Linux kernel commit:
  02c0cd2: x86/tsc_msr: Remove irqoff around MSR-based TSC enumeration

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
---

 drivers/timer/tsc_timer.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/timer/tsc_timer.c b/drivers/timer/tsc_timer.c
index b242e74..4d1fc9c 100644
--- a/drivers/timer/tsc_timer.c
+++ b/drivers/timer/tsc_timer.c
@@ -71,11 +71,16 @@ static int match_cpu(u8 family, u8 model)
 	(freq_desc_tables[cpu_index].freqs[freq_id])
 
 /*
- * Do MSR calibration only for known/supported CPUs.
+ * TSC on Intel Atom SoCs capable of determining TSC frequency by MSR is
+ * reliable and the frequency is known (provided by HW).
  *
- * Returns the calibration value or 0 if MSR calibration failed.
+ * On these platforms PIT/HPET is generally not available so calibration won't
+ * work at all and there is no other clocksource to act as a watchdog for the
+ * TSC, so we have no other choice than to trust it.
+ *
+ * Returns the TSC frequency in MHz or 0 if HW does not provide it.
  */
-static unsigned long __maybe_unused try_msr_calibrate_tsc(void)
+static unsigned long __maybe_unused cpu_mhz_from_msr(void)
 {
 	u32 lo, hi, ratio, freq_id, freq;
 	unsigned long res;
@@ -336,7 +341,7 @@ static int tsc_timer_probe(struct udevice *dev)
 	if (!uc_priv->clock_rate) {
 		unsigned long fast_calibrate;
 
-		fast_calibrate = try_msr_calibrate_tsc();
+		fast_calibrate = cpu_mhz_from_msr();
 		if (!fast_calibrate) {
 			fast_calibrate = quick_pit_calibrate();
 			if (!fast_calibrate)
-- 
2.9.2

[U-Boot] [PATCH 6/6] x86: tsc: Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr()

[Simon Glass]

On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
> Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr(), as that
> better describes what the routine does.
>
> This keeps in sync with Linux kernel commit:
>   02c0cd2: x86/tsc_msr: Remove irqoff around MSR-based TSC enumeration
>
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>
>  drivers/timer/tsc_timer.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)
>

Reviewed-by: Simon Glass <sjg@chromium.org>

[U-Boot] [PATCH 6/6] x86: tsc: Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr()

[Bin Meng]

On Tue, Aug 1, 2017 at 5:11 PM, Simon Glass <sjg@chromium.org> wrote:
> On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
>> Rename try_msr_calibrate_tsc() to cpu_mhz_from_msr(), as that
>> better describes what the routine does.
>>
>> This keeps in sync with Linux kernel commit:
>>   02c0cd2: x86/tsc_msr: Remove irqoff around MSR-based TSC enumeration
>>
>> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
>> ---
>>
>>  drivers/timer/tsc_timer.c | 13 +++++++++----
>>  1 file changed, 9 insertions(+), 4 deletions(-)
>>
>
> Reviewed-by: Simon Glass <sjg@chromium.org>

applied to u-boot-x86, thanks!

[U-Boot] [PATCH 1/6] x86: tsc: Read all ratio bits from MSR_PLATFORM_INFO

[Simon Glass]

On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
> Currently we read the tsc radio like this:
>
>         ratio = (MSR_PLATFORM_INFO >> 8) & 0x1f;
>
> Thus we get bit 8-12 of MSR_PLATFORM_INFO, however according to the
> Intel manual, the ratio bits are bit 8-15.
>
> Fix this problem by masking 0xff instead.
>
> This keeps in sync with Linux kernel commit:
>   886123f: x86/tsc: Read all ratio bits from MSR_PLATFORM_INFO
>
> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
> ---
>
>  drivers/timer/tsc_timer.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Reviewed-by: Simon Glass <sjg@chromium.org>

[U-Boot] [PATCH 1/6] x86: tsc: Read all ratio bits from MSR_PLATFORM_INFO

[Bin Meng]

On Tue, Aug 1, 2017 at 5:10 PM, Simon Glass <sjg@chromium.org> wrote:
> On 25 July 2017 at 21:12, Bin Meng <bmeng.cn@gmail.com> wrote:
>> Currently we read the tsc radio like this:
>>
>>         ratio = (MSR_PLATFORM_INFO >> 8) & 0x1f;
>>
>> Thus we get bit 8-12 of MSR_PLATFORM_INFO, however according to the
>> Intel manual, the ratio bits are bit 8-15.
>>
>> Fix this problem by masking 0xff instead.
>>
>> This keeps in sync with Linux kernel commit:
>>   886123f: x86/tsc: Read all ratio bits from MSR_PLATFORM_INFO
>>
>> Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
>> ---
>>
>>  drivers/timer/tsc_timer.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> Reviewed-by: Simon Glass <sjg@chromium.org>

applied to u-boot-x86, thanks!