From: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To: linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
tglx@linutronix.de, daniel.lezcano@linaro.org
Cc: linux-arm-kernel@lists.infradead.org, khilman@baylibre.com,
carlo@caione.org,
Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Subject: [PATCH 2/2] clocksource: meson6_timer: implement ARM delay timer
Date: Sun, 28 Oct 2018 13:55:01 +0100 [thread overview]
Message-ID: <20181028125501.17336-3-martin.blumenstingl@googlemail.com> (raw)
In-Reply-To: <20181028125501.17336-1-martin.blumenstingl@googlemail.com>
Implement an ARM delay timer to be used for udelay(). This allows us to
skip the delay loop calibration at boot.
With this patch udelay() is now independent of CPU frequency changes.
This is a good thing on Meson8, Meson8b and Meson8m2 because changing
the CPU frequency requires running the CPU clock off the XTAL while
changing the PLL or it's dividers. After changing the CPU clocks we need
to wait a few usecs for the clock to become stable. So having an
udelay() implementation that doesn't depend on the CPU frequency is
beneficial.
Suggested-by: Jianxin Pan <jianxin.pan@amlogic.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
drivers/clocksource/meson6_timer.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/clocksource/meson6_timer.c b/drivers/clocksource/meson6_timer.c
index c622135bee9d..5ee2a575069b 100644
--- a/drivers/clocksource/meson6_timer.c
+++ b/drivers/clocksource/meson6_timer.c
@@ -22,6 +22,10 @@
#include <linux/of_address.h>
#include <linux/of_irq.h>
+#ifdef CONFIG_ARM
+#include <linux/delay.h>
+#endif
+
enum meson6_timera_input_clock {
MESON_TIMERA_CLOCK_1US = 0x0,
MESON_TIMERA_CLOCK_10US = 0x1,
@@ -60,6 +64,18 @@ enum meson6_timere_input_clock {
static void __iomem *timer_base;
+#ifdef CONFIG_ARM
+static unsigned long meson6_read_current_timer(void)
+{
+ return readl_relaxed(timer_base + MESON_ISA_TIMERE);
+}
+
+static struct delay_timer meson6_delay_timer = {
+ .read_current_timer = meson6_read_current_timer,
+ .freq = 1000 * 1000,
+};
+#endif
+
static u64 notrace meson6_timer_sched_read(void)
{
return (u64)readl(timer_base + MESON_ISA_TIMERE);
@@ -198,6 +214,12 @@ static int __init meson6_timer_init(struct device_node *node)
clockevents_config_and_register(&meson6_clockevent, USEC_PER_SEC,
1, 0xfffe);
+
+#ifdef CONFIG_ARM
+ /* Also use MESON_ISA_TIMERE for delays */
+ register_current_timer_delay(&meson6_delay_timer);
+#endif
+
return 0;
}
TIMER_OF_DECLARE(meson6, "amlogic,meson6-timer",
--
2.19.1
WARNING: multiple messages have this Message-ID (diff)
From: martin.blumenstingl@googlemail.com (Martin Blumenstingl)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 2/2] clocksource: meson6_timer: implement ARM delay timer
Date: Sun, 28 Oct 2018 13:55:01 +0100 [thread overview]
Message-ID: <20181028125501.17336-3-martin.blumenstingl@googlemail.com> (raw)
In-Reply-To: <20181028125501.17336-1-martin.blumenstingl@googlemail.com>
Implement an ARM delay timer to be used for udelay(). This allows us to
skip the delay loop calibration at boot.
With this patch udelay() is now independent of CPU frequency changes.
This is a good thing on Meson8, Meson8b and Meson8m2 because changing
the CPU frequency requires running the CPU clock off the XTAL while
changing the PLL or it's dividers. After changing the CPU clocks we need
to wait a few usecs for the clock to become stable. So having an
udelay() implementation that doesn't depend on the CPU frequency is
beneficial.
Suggested-by: Jianxin Pan <jianxin.pan@amlogic.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
drivers/clocksource/meson6_timer.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/clocksource/meson6_timer.c b/drivers/clocksource/meson6_timer.c
index c622135bee9d..5ee2a575069b 100644
--- a/drivers/clocksource/meson6_timer.c
+++ b/drivers/clocksource/meson6_timer.c
@@ -22,6 +22,10 @@
#include <linux/of_address.h>
#include <linux/of_irq.h>
+#ifdef CONFIG_ARM
+#include <linux/delay.h>
+#endif
+
enum meson6_timera_input_clock {
MESON_TIMERA_CLOCK_1US = 0x0,
MESON_TIMERA_CLOCK_10US = 0x1,
@@ -60,6 +64,18 @@ enum meson6_timere_input_clock {
static void __iomem *timer_base;
+#ifdef CONFIG_ARM
+static unsigned long meson6_read_current_timer(void)
+{
+ return readl_relaxed(timer_base + MESON_ISA_TIMERE);
+}
+
+static struct delay_timer meson6_delay_timer = {
+ .read_current_timer = meson6_read_current_timer,
+ .freq = 1000 * 1000,
+};
+#endif
+
static u64 notrace meson6_timer_sched_read(void)
{
return (u64)readl(timer_base + MESON_ISA_TIMERE);
@@ -198,6 +214,12 @@ static int __init meson6_timer_init(struct device_node *node)
clockevents_config_and_register(&meson6_clockevent, USEC_PER_SEC,
1, 0xfffe);
+
+#ifdef CONFIG_ARM
+ /* Also use MESON_ISA_TIMERE for delays */
+ register_current_timer_delay(&meson6_delay_timer);
+#endif
+
return 0;
}
TIMER_OF_DECLARE(meson6, "amlogic,meson6-timer",
--
2.19.1
WARNING: multiple messages have this Message-ID (diff)
From: martin.blumenstingl@googlemail.com (Martin Blumenstingl)
To: linus-amlogic@lists.infradead.org
Subject: [PATCH 2/2] clocksource: meson6_timer: implement ARM delay timer
Date: Sun, 28 Oct 2018 13:55:01 +0100 [thread overview]
Message-ID: <20181028125501.17336-3-martin.blumenstingl@googlemail.com> (raw)
In-Reply-To: <20181028125501.17336-1-martin.blumenstingl@googlemail.com>
Implement an ARM delay timer to be used for udelay(). This allows us to
skip the delay loop calibration at boot.
With this patch udelay() is now independent of CPU frequency changes.
This is a good thing on Meson8, Meson8b and Meson8m2 because changing
the CPU frequency requires running the CPU clock off the XTAL while
changing the PLL or it's dividers. After changing the CPU clocks we need
to wait a few usecs for the clock to become stable. So having an
udelay() implementation that doesn't depend on the CPU frequency is
beneficial.
Suggested-by: Jianxin Pan <jianxin.pan@amlogic.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
drivers/clocksource/meson6_timer.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/clocksource/meson6_timer.c b/drivers/clocksource/meson6_timer.c
index c622135bee9d..5ee2a575069b 100644
--- a/drivers/clocksource/meson6_timer.c
+++ b/drivers/clocksource/meson6_timer.c
@@ -22,6 +22,10 @@
#include <linux/of_address.h>
#include <linux/of_irq.h>
+#ifdef CONFIG_ARM
+#include <linux/delay.h>
+#endif
+
enum meson6_timera_input_clock {
MESON_TIMERA_CLOCK_1US = 0x0,
MESON_TIMERA_CLOCK_10US = 0x1,
@@ -60,6 +64,18 @@ enum meson6_timere_input_clock {
static void __iomem *timer_base;
+#ifdef CONFIG_ARM
+static unsigned long meson6_read_current_timer(void)
+{
+ return readl_relaxed(timer_base + MESON_ISA_TIMERE);
+}
+
+static struct delay_timer meson6_delay_timer = {
+ .read_current_timer = meson6_read_current_timer,
+ .freq = 1000 * 1000,
+};
+#endif
+
static u64 notrace meson6_timer_sched_read(void)
{
return (u64)readl(timer_base + MESON_ISA_TIMERE);
@@ -198,6 +214,12 @@ static int __init meson6_timer_init(struct device_node *node)
clockevents_config_and_register(&meson6_clockevent, USEC_PER_SEC,
1, 0xfffe);
+
+#ifdef CONFIG_ARM
+ /* Also use MESON_ISA_TIMERE for delays */
+ register_current_timer_delay(&meson6_delay_timer);
+#endif
+
return 0;
}
TIMER_OF_DECLARE(meson6, "amlogic,meson6-timer",
--
2.19.1
next prev parent reply other threads:[~2018-10-28 12:55 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-28 12:54 [PATCH 0/2] clocksource/meson6_timer: implement ARM delay timer Martin Blumenstingl
2018-10-28 12:54 ` Martin Blumenstingl
2018-10-28 12:54 ` Martin Blumenstingl
2018-10-28 12:55 ` [PATCH 1/2] clocksource: meson6_timer: use register names from the datasheet Martin Blumenstingl
2018-10-28 12:55 ` Martin Blumenstingl
2018-10-28 12:55 ` Martin Blumenstingl
2018-11-15 1:35 ` Daniel Lezcano
2018-11-15 1:35 ` Daniel Lezcano
2018-11-15 1:35 ` Daniel Lezcano
2018-11-15 6:23 ` Martin Blumenstingl
2018-11-15 6:23 ` Martin Blumenstingl
2018-11-15 6:23 ` Martin Blumenstingl
2018-11-15 12:15 ` Daniel Lezcano
2018-11-15 12:15 ` Daniel Lezcano
2018-11-15 12:15 ` Daniel Lezcano
2018-10-28 12:55 ` Martin Blumenstingl [this message]
2018-10-28 12:55 ` [PATCH 2/2] clocksource: meson6_timer: implement ARM delay timer Martin Blumenstingl
2018-10-28 12:55 ` Martin Blumenstingl
2018-11-14 22:33 ` [PATCH 0/2] clocksource/meson6_timer: " Martin Blumenstingl
2018-11-14 22:33 ` Martin Blumenstingl
2018-11-14 22:33 ` Martin Blumenstingl
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