[PATCH v2 0/2] Add system timer driver for Mediatek SoCs

[PATCH v2 0/2] Add system timer driver for Mediatek SoCs

[Stanley Chu]

This patch adds a new driver for system timer on the Mediatek SoCs.

Changes since v1:
- Use timer_of structure and APIs to make driver more clean.
- Remove unnecessary headers.
- Use fixed-clock.
- Fix indent.


Stanley Chu (2):
  dt-bindings: Add mtk-systimer bindings
  clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

 .../bindings/timer/mediatek,mtk-systimer.txt       |  18 +++
 drivers/clocksource/Kconfig                        |  13 +-
 drivers/clocksource/Makefile                       |   1 +
 drivers/clocksource/mtk_systimer.c                 | 132 +++++++++++++++++++++
 4 files changed, 162 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
 create mode 100644 drivers/clocksource/mtk_systimer.c

[PATCH v2 0/2] Add system timer driver for Mediatek SoCs

[Stanley Chu]

This patch adds a new driver for system timer on the Mediatek SoCs.

Changes since v1:
- Use timer_of structure and APIs to make driver more clean.
- Remove unnecessary headers.
- Use fixed-clock.
- Fix indent.


Stanley Chu (2):
  dt-bindings: Add mtk-systimer bindings
  clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

 .../bindings/timer/mediatek,mtk-systimer.txt       |  18 +++
 drivers/clocksource/Kconfig                        |  13 +-
 drivers/clocksource/Makefile                       |   1 +
 drivers/clocksource/mtk_systimer.c                 | 132 +++++++++++++++++++++
 4 files changed, 162 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
 create mode 100644 drivers/clocksource/mtk_systimer.c

[PATCH v2 1/2] dt-bindings: Add mtk-systimer bindings

[Stanley Chu]

Add binding documentation for the System Timer driver of
the Mediatek SoCs.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
---
 .../bindings/timer/mediatek,mtk-systimer.txt       |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt

diff --git a/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt b/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
new file mode 100644
index 0000000..7a5bde6
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
@@ -0,0 +1,18 @@
+Mediatek System Timers
+----------------------
+
+Required properties:
+- compatible: Should contain
+	"mediatek,sys_timer" for those platforms which support system timer.
+- reg: Should contain the location and length for system timer registers.
+- clocks: System timer is drived by system clock.
+
+Examples:
+
+	sys_timer@10017000 {
+		compatible = "mediatek,sys_timer";
+		reg = <0 0x10017000 0 0x1000>;
+		interrupts = <GIC_SPI 194 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&sys_clk>;
+	};
+
-- 
1.7.9.5

[PATCH v2 1/2] dt-bindings: Add mtk-systimer bindings

[Stanley Chu]

Add binding documentation for the System Timer driver of
the Mediatek SoCs.

Signed-off-by: Stanley Chu <stanley.chu-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
---
 .../bindings/timer/mediatek,mtk-systimer.txt       |   18 ++++++++++++++++++
 1 file changed, 18 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt

diff --git a/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt b/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
new file mode 100644
index 0000000..7a5bde6
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
@@ -0,0 +1,18 @@
+Mediatek System Timers
+----------------------
+
+Required properties:
+- compatible: Should contain
+	"mediatek,sys_timer" for those platforms which support system timer.
+- reg: Should contain the location and length for system timer registers.
+- clocks: System timer is drived by system clock.
+
+Examples:
+
+	sys_timer@10017000 {
+		compatible = "mediatek,sys_timer";
+		reg = <0 0x10017000 0 0x1000>;
+		interrupts = <GIC_SPI 194 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&sys_clk>;
+	};
+
-- 
1.7.9.5

[PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Stanley Chu]

This patch adds a new clock event for the timer
found on the Mediatek SoCs.

The Mediatek System Timer has several 32-bit timers.
Only one timer is used by this driver as a clock event
supporting oneshot events.

The System Timer can be run with two clocks. A 13 MHz system
clock and the RTC clock running at 32 KHz. This implementation
uses the system clock with no clock source divider.

The interrupts are shared between the different timers.
We just enable one interrupt for the clock event. The clock
event timer is used by all cores.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
---
 drivers/clocksource/Kconfig        |   13 +++-
 drivers/clocksource/Makefile       |    1 +
 drivers/clocksource/mtk_systimer.c |  132 ++++++++++++++++++++++++++++++++++++
 3 files changed, 144 insertions(+), 2 deletions(-)
 create mode 100644 drivers/clocksource/mtk_systimer.c

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index dec0dd8..362c110 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -442,12 +442,21 @@ config SYS_SUPPORTS_SH_CMT
         bool
 
 config MTK_TIMER
-	bool "Mediatek timer driver" if COMPILE_TEST
+	bool "Mediatek general purpose timer driver" if COMPILE_TEST
 	depends on HAS_IOMEM
 	select TIMER_OF
 	select CLKSRC_MMIO
 	help
-	  Support for Mediatek timer driver.
+	  Support for Mediatek General Purpose Timer (GPT) driver.
+
+config MTK_TIMER_SYSTIMER
+	bool "Mediatek system timer driver" if COMPILE_TEST
+	depends on HAS_IOMEM
+	select TIMER_OF
+	select CLKSRC_MMIO
+	help
+	  Support for Mediatek System Timer (sys_timer) driver used as
+	  a clock event supporting oneshot events.
 
 config SPRD_TIMER
 	bool "Spreadtrum timer driver" if EXPERT
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 00caf37..cdd34b2 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_FSL_FTM_TIMER)	+= fsl_ftm_timer.o
 obj-$(CONFIG_VF_PIT_TIMER)	+= vf_pit_timer.o
 obj-$(CONFIG_CLKSRC_QCOM)	+= qcom-timer.o
 obj-$(CONFIG_MTK_TIMER)		+= mtk_timer.o
+obj-$(CONFIG_MTK_TIMER_SYSTIMER)	+= mtk_systimer.o
 obj-$(CONFIG_CLKSRC_PISTACHIO)	+= time-pistachio.o
 obj-$(CONFIG_CLKSRC_TI_32K)	+= timer-ti-32k.o
 obj-$(CONFIG_CLKSRC_NPS)	+= timer-nps.o
diff --git a/drivers/clocksource/mtk_systimer.c b/drivers/clocksource/mtk_systimer.c
new file mode 100644
index 0000000..77161bb
--- /dev/null
+++ b/drivers/clocksource/mtk_systimer.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+//  Copyright (C) 2018 MediaTek Inc.
+
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/io.h>
+#include "timer-of.h"
+
+/* registers */
+#define STMR_CON                  (0x0)
+#define STMR_VAL                  (0x4)
+
+#define TIMER_REG_CON(to)         (timer_of_base(to) + STMR_CON)
+#define TIMER_REG_VAL(to)         (timer_of_base(to) + STMR_VAL)
+
+/* STMR_CON */
+#define STMR_CON_EN               BIT(0)
+#define STMR_CON_IRQ_EN           BIT(1)
+#define STMR_CON_IRQ_CLR          BIT(4)
+
+#define TIMER_SYNC_TICKS          3
+
+static void mtk_stmr_reset(struct timer_of *to)
+{
+	/* Clear IRQ */
+	writel(STMR_CON_IRQ_CLR | STMR_CON_EN, TIMER_REG_CON(to));
+
+	/* Reset counter */
+	writel(0, TIMER_REG_VAL(to));
+
+	/* Disable timer */
+	writel(0, TIMER_REG_CON(to));
+}
+
+static void mtk_stmr_ack_irq(struct timer_of *to)
+{
+	mtk_stmr_reset(to);
+}
+
+static irqreturn_t mtk_stmr_handler(int irq, void *dev_id)
+{
+	struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
+	struct timer_of *to = to_timer_of(clkevt);
+
+	mtk_stmr_ack_irq(to);
+	clkevt->event_handler(clkevt);
+
+	return IRQ_HANDLED;
+}
+
+static int mtk_stmr_clkevt_next_event(unsigned long ticks,
+				      struct clock_event_device *clkevt)
+{
+	struct timer_of *to = to_timer_of(clkevt);
+
+	/*
+	 * reset timer first because we do not expect interrupt is triggered
+	 * by old compare value.
+	 */
+	mtk_stmr_reset(to);
+
+	writel(STMR_CON_EN, TIMER_REG_CON(to));
+
+	writel(ticks, TIMER_REG_VAL(to));
+
+	writel(STMR_CON_EN | STMR_CON_IRQ_EN, TIMER_REG_CON(to));
+
+	return 0;
+}
+
+static int mtk_stmr_clkevt_shutdown(struct clock_event_device *clkevt)
+{
+	mtk_stmr_reset(to_timer_of(clkevt));
+
+	return 0;
+}
+
+static int mtk_stmr_clkevt_resume(struct clock_event_device *clkevt)
+{
+	return mtk_stmr_clkevt_shutdown(clkevt);
+}
+
+static int mtk_stmr_clkevt_oneshot(struct clock_event_device *clkevt)
+{
+	return 0;
+}
+
+static struct timer_of to = {
+	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
+
+	.clkevt = {
+		.name = "mtk-clkevt",
+		.rating = 300,
+		.features = CLOCK_EVT_FEAT_DYNIRQ | CLOCK_EVT_FEAT_ONESHOT,
+		.set_state_shutdown = mtk_stmr_clkevt_shutdown,
+		.set_state_oneshot = mtk_stmr_clkevt_oneshot,
+		.tick_resume = mtk_stmr_clkevt_resume,
+		.set_next_event = mtk_stmr_clkevt_next_event,
+		.cpumask = cpu_possible_mask,
+	},
+
+	.of_irq = {
+		.handler = mtk_stmr_handler,
+		.flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_TRIGGER_HIGH |
+			 IRQF_PERCPU,
+	},
+};
+
+static int __init mtk_stmr_init(struct device_node *node)
+{
+	int ret;
+
+	ret = timer_of_init(node, &to);
+	if (ret)
+		return ret;
+
+	mtk_stmr_reset(&to);
+
+	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
+					TIMER_SYNC_TICKS, 0xffffffff);
+
+	pr_info("mtk_stmr: irq=%d, rate=%lu, max_ns: %llu, min_ns: %llu\n",
+		timer_of_irq(&to), timer_of_rate(&to),
+		to.clkevt.max_delta_ns, to.clkevt.min_delta_ns);
+
+	return ret;
+}
+
+TIMER_OF_DECLARE(mtk_systimer, "mediatek,sys_timer", mtk_stmr_init);
-- 
1.7.9.5

[PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Stanley Chu]

This patch adds a new clock event for the timer
found on the Mediatek SoCs.

The Mediatek System Timer has several 32-bit timers.
Only one timer is used by this driver as a clock event
supporting oneshot events.

The System Timer can be run with two clocks. A 13 MHz system
clock and the RTC clock running at 32 KHz. This implementation
uses the system clock with no clock source divider.

The interrupts are shared between the different timers.
We just enable one interrupt for the clock event. The clock
event timer is used by all cores.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
---
 drivers/clocksource/Kconfig        |   13 +++-
 drivers/clocksource/Makefile       |    1 +
 drivers/clocksource/mtk_systimer.c |  132 ++++++++++++++++++++++++++++++++++++
 3 files changed, 144 insertions(+), 2 deletions(-)
 create mode 100644 drivers/clocksource/mtk_systimer.c

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index dec0dd8..362c110 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -442,12 +442,21 @@ config SYS_SUPPORTS_SH_CMT
         bool
 
 config MTK_TIMER
-	bool "Mediatek timer driver" if COMPILE_TEST
+	bool "Mediatek general purpose timer driver" if COMPILE_TEST
 	depends on HAS_IOMEM
 	select TIMER_OF
 	select CLKSRC_MMIO
 	help
-	  Support for Mediatek timer driver.
+	  Support for Mediatek General Purpose Timer (GPT) driver.
+
+config MTK_TIMER_SYSTIMER
+	bool "Mediatek system timer driver" if COMPILE_TEST
+	depends on HAS_IOMEM
+	select TIMER_OF
+	select CLKSRC_MMIO
+	help
+	  Support for Mediatek System Timer (sys_timer) driver used as
+	  a clock event supporting oneshot events.
 
 config SPRD_TIMER
 	bool "Spreadtrum timer driver" if EXPERT
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 00caf37..cdd34b2 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -50,6 +50,7 @@ obj-$(CONFIG_FSL_FTM_TIMER)	+= fsl_ftm_timer.o
 obj-$(CONFIG_VF_PIT_TIMER)	+= vf_pit_timer.o
 obj-$(CONFIG_CLKSRC_QCOM)	+= qcom-timer.o
 obj-$(CONFIG_MTK_TIMER)		+= mtk_timer.o
+obj-$(CONFIG_MTK_TIMER_SYSTIMER)	+= mtk_systimer.o
 obj-$(CONFIG_CLKSRC_PISTACHIO)	+= time-pistachio.o
 obj-$(CONFIG_CLKSRC_TI_32K)	+= timer-ti-32k.o
 obj-$(CONFIG_CLKSRC_NPS)	+= timer-nps.o
diff --git a/drivers/clocksource/mtk_systimer.c b/drivers/clocksource/mtk_systimer.c
new file mode 100644
index 0000000..77161bb
--- /dev/null
+++ b/drivers/clocksource/mtk_systimer.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0+
+//
+//  Copyright (C) 2018 MediaTek Inc.
+
+#include <linux/interrupt.h>
+#include <linux/irqreturn.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/io.h>
+#include "timer-of.h"
+
+/* registers */
+#define STMR_CON                  (0x0)
+#define STMR_VAL                  (0x4)
+
+#define TIMER_REG_CON(to)         (timer_of_base(to) + STMR_CON)
+#define TIMER_REG_VAL(to)         (timer_of_base(to) + STMR_VAL)
+
+/* STMR_CON */
+#define STMR_CON_EN               BIT(0)
+#define STMR_CON_IRQ_EN           BIT(1)
+#define STMR_CON_IRQ_CLR          BIT(4)
+
+#define TIMER_SYNC_TICKS          3
+
+static void mtk_stmr_reset(struct timer_of *to)
+{
+	/* Clear IRQ */
+	writel(STMR_CON_IRQ_CLR | STMR_CON_EN, TIMER_REG_CON(to));
+
+	/* Reset counter */
+	writel(0, TIMER_REG_VAL(to));
+
+	/* Disable timer */
+	writel(0, TIMER_REG_CON(to));
+}
+
+static void mtk_stmr_ack_irq(struct timer_of *to)
+{
+	mtk_stmr_reset(to);
+}
+
+static irqreturn_t mtk_stmr_handler(int irq, void *dev_id)
+{
+	struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
+	struct timer_of *to = to_timer_of(clkevt);
+
+	mtk_stmr_ack_irq(to);
+	clkevt->event_handler(clkevt);
+
+	return IRQ_HANDLED;
+}
+
+static int mtk_stmr_clkevt_next_event(unsigned long ticks,
+				      struct clock_event_device *clkevt)
+{
+	struct timer_of *to = to_timer_of(clkevt);
+
+	/*
+	 * reset timer first because we do not expect interrupt is triggered
+	 * by old compare value.
+	 */
+	mtk_stmr_reset(to);
+
+	writel(STMR_CON_EN, TIMER_REG_CON(to));
+
+	writel(ticks, TIMER_REG_VAL(to));
+
+	writel(STMR_CON_EN | STMR_CON_IRQ_EN, TIMER_REG_CON(to));
+
+	return 0;
+}
+
+static int mtk_stmr_clkevt_shutdown(struct clock_event_device *clkevt)
+{
+	mtk_stmr_reset(to_timer_of(clkevt));
+
+	return 0;
+}
+
+static int mtk_stmr_clkevt_resume(struct clock_event_device *clkevt)
+{
+	return mtk_stmr_clkevt_shutdown(clkevt);
+}
+
+static int mtk_stmr_clkevt_oneshot(struct clock_event_device *clkevt)
+{
+	return 0;
+}
+
+static struct timer_of to = {
+	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
+
+	.clkevt = {
+		.name = "mtk-clkevt",
+		.rating = 300,
+		.features = CLOCK_EVT_FEAT_DYNIRQ | CLOCK_EVT_FEAT_ONESHOT,
+		.set_state_shutdown = mtk_stmr_clkevt_shutdown,
+		.set_state_oneshot = mtk_stmr_clkevt_oneshot,
+		.tick_resume = mtk_stmr_clkevt_resume,
+		.set_next_event = mtk_stmr_clkevt_next_event,
+		.cpumask = cpu_possible_mask,
+	},
+
+	.of_irq = {
+		.handler = mtk_stmr_handler,
+		.flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_TRIGGER_HIGH |
+			 IRQF_PERCPU,
+	},
+};
+
+static int __init mtk_stmr_init(struct device_node *node)
+{
+	int ret;
+
+	ret = timer_of_init(node, &to);
+	if (ret)
+		return ret;
+
+	mtk_stmr_reset(&to);
+
+	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
+					TIMER_SYNC_TICKS, 0xffffffff);
+
+	pr_info("mtk_stmr: irq=%d, rate=%lu, max_ns: %llu, min_ns: %llu\n",
+		timer_of_irq(&to), timer_of_rate(&to),
+		to.clkevt.max_delta_ns, to.clkevt.min_delta_ns);
+
+	return ret;
+}
+
+TIMER_OF_DECLARE(mtk_systimer, "mediatek,sys_timer", mtk_stmr_init);
-- 
1.7.9.5

Re: [PATCH v2 1/2] dt-bindings: Add mtk-systimer bindings

[Daniel Lezcano]

On 27/06/2018 09:53, Stanley Chu wrote:
> Add binding documentation for the System Timer driver of
> the Mediatek SoCs.
> 
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
> ---


>  .../bindings/timer/mediatek,mtk-systimer.txt       |   18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
> 
> diff --git a/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt b/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
> new file mode 100644
> index 0000000..7a5bde6
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/timer/mediatek,mtk-systimer.txt
> @@ -0,0 +1,18 @@
> +Mediatek System Timers
> +----------------------
> +
> +Required properties:
> +- compatible: Should contain
> +	"mediatek,sys_timer" for those platforms which support system timer.
> +- reg: Should contain the location and length for system timer registers.
> +- clocks: System timer is drived by system clock.
> +
> +Examples:
> +
> +	sys_timer@10017000 {
> +		compatible = "mediatek,sys_timer";
> +		reg = <0 0x10017000 0 0x1000>;
> +		interrupts = <GIC_SPI 194 IRQ_TYPE_LEVEL_HIGH>;
> +		clocks = <&sys_clk>;
> +	};
> +

Actually this binding already exists for mediatek timers, it is useless
to add a new one.

I note the binding in

Documentation/devicetree/bindings/timer/mediatek,mtk-timer.txt

contains:

 clocks = <&system_clk>, <&rtc_clk>

However the existing driver does only use <&system_clk> AFAICT, I'm
questioning if <&rtc_clk> is really needed.

So, I suggest you sort out and fixup the rtc_clk thing (drop it) and
then just add your new platform in the list in this binding.


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Re: [PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Daniel Lezcano]

On 27/06/2018 09:53, Stanley Chu wrote:
> This patch adds a new clock event for the timer
> found on the Mediatek SoCs.
> 
> The Mediatek System Timer has several 32-bit timers.
> Only one timer is used by this driver as a clock event
> supporting oneshot events.
> 
> The System Timer can be run with two clocks. A 13 MHz system
> clock and the RTC clock running at 32 KHz. This implementation
> uses the system clock with no clock source divider.

Recent platforms have the arch_arm_timer and it will be always selected.

What is the benefit of adding this timer ?


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Re: [PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Stanley Chu]

On Wed, 2018-06-27 at 11:39 +0200, Daniel Lezcano wrote:
> On 27/06/2018 09:53, Stanley Chu wrote:
> > This patch adds a new clock event for the timer
> > found on the Mediatek SoCs.
> > 
> > The Mediatek System Timer has several 32-bit timers.
> > Only one timer is used by this driver as a clock event
> > supporting oneshot events.
> > 
> > The System Timer can be run with two clocks. A 13 MHz system
> > clock and the RTC clock running at 32 KHz. This implementation
> > uses the system clock with no clock source divider.
> 
> Recent platforms have the arch_arm_timer and it will be always selected.
> 
> What is the benefit of adding this timer ?
> 
> 
Hi Daniel,

To save power as much as possible, our platform enables
"arch_timer_c3stop" in arch_arm_timer, and thus another always-on timer
is required for tick-broadcasting. System Timer is introduced for above
purpose.

Thanks.
Stanley Chu

Re: [PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Stanley Chu]

On Wed, 2018-06-27 at 11:39 +0200, Daniel Lezcano wrote:
> On 27/06/2018 09:53, Stanley Chu wrote:
> > This patch adds a new clock event for the timer
> > found on the Mediatek SoCs.
> > 
> > The Mediatek System Timer has several 32-bit timers.
> > Only one timer is used by this driver as a clock event
> > supporting oneshot events.
> > 
> > The System Timer can be run with two clocks. A 13 MHz system
> > clock and the RTC clock running at 32 KHz. This implementation
> > uses the system clock with no clock source divider.
> 
> Recent platforms have the arch_arm_timer and it will be always selected.
> 
> What is the benefit of adding this timer ?
> 
> 
Hi Daniel,

To save power as much as possible, our platform enables
"arch_timer_c3stop" in arch_arm_timer, and thus another always-on timer
is required for tick-broadcasting. System Timer is introduced for above
purpose.

Thanks.
Stanley Chu

Re: [PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Daniel Lezcano]

On 27/06/2018 11:50, Stanley Chu wrote:
> On Wed, 2018-06-27 at 11:39 +0200, Daniel Lezcano wrote:
>> On 27/06/2018 09:53, Stanley Chu wrote:
>>> This patch adds a new clock event for the timer
>>> found on the Mediatek SoCs.
>>>
>>> The Mediatek System Timer has several 32-bit timers.
>>> Only one timer is used by this driver as a clock event
>>> supporting oneshot events.
>>>
>>> The System Timer can be run with two clocks. A 13 MHz system
>>> clock and the RTC clock running at 32 KHz. This implementation
>>> uses the system clock with no clock source divider.
>>
>> Recent platforms have the arch_arm_timer and it will be always selected.
>>
>> What is the benefit of adding this timer ?
>>
>>
> Hi Daniel,
> 
> To save power as much as possible, our platform enables
> "arch_timer_c3stop" in arch_arm_timer, and thus another always-on timer
> is required for tick-broadcasting. System Timer is introduced for above
> purpose

Obviously :)



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Re: [PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Daniel Lezcano]

On 27/06/2018 09:53, Stanley Chu wrote:
> This patch adds a new clock event for the timer
> found on the Mediatek SoCs.
> 
> The Mediatek System Timer has several 32-bit timers.
> Only one timer is used by this driver as a clock event
> supporting oneshot events.
> 
> The System Timer can be run with two clocks. A 13 MHz system
> clock and the RTC clock running at 32 KHz. This implementation
> uses the system clock with no clock source divider.
> The interrupts are shared between the different timers.
> We just enable one interrupt for the clock event. The clock
> event timer is used by all cores.
> 
> Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
> ---
>  drivers/clocksource/Kconfig        |   13 +++-
>  drivers/clocksource/Makefile       |    1 +
>  drivers/clocksource/mtk_systimer.c |  132 ++++++++++++++++++++++++++++++++++++

Please merge mtk_systimer.c and mtk_timer.c into a single file:

timer-mediatek.c

Patch 1:

 git mv mtk_timer.c timer-mediatek.c
 Change the name in Makefile

Patch 2:

 Change function prefix name to _gpt_

Patch 2.1 [optional but recommended] :

 Move the gpt's init code to timer-of

Patch 3:

 Add code for syst in timer-mediatek.c



A couple of comments below.

>  3 files changed, 144 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/clocksource/mtk_systimer.c
> 
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index dec0dd8..362c110 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -442,12 +442,21 @@ config SYS_SUPPORTS_SH_CMT
>          bool
>  
>  config MTK_TIMER
> -	bool "Mediatek timer driver" if COMPILE_TEST
> +	bool "Mediatek general purpose timer driver" if COMPILE_TEST
>  	depends on HAS_IOMEM
>  	select TIMER_OF
>  	select CLKSRC_MMIO
>  	help
> -	  Support for Mediatek timer driver.
> +	  Support for Mediatek General Purpose Timer (GPT) driver.
> +
> +config MTK_TIMER_SYSTIMER
> +	bool "Mediatek system timer driver" if COMPILE_TEST
> +	depends on HAS_IOMEM
> +	select TIMER_OF
> +	select CLKSRC_MMIO
> +	help
> +	  Support for Mediatek System Timer (sys_timer) driver used as
> +	  a clock event supporting oneshot events.
>  
>  config SPRD_TIMER
>  	bool "Spreadtrum timer driver" if EXPERT
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 00caf37..cdd34b2 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -50,6 +50,7 @@ obj-$(CONFIG_FSL_FTM_TIMER)	+= fsl_ftm_timer.o
>  obj-$(CONFIG_VF_PIT_TIMER)	+= vf_pit_timer.o
>  obj-$(CONFIG_CLKSRC_QCOM)	+= qcom-timer.o
>  obj-$(CONFIG_MTK_TIMER)		+= mtk_timer.o
> +obj-$(CONFIG_MTK_TIMER_SYSTIMER)	+= mtk_systimer.o
>  obj-$(CONFIG_CLKSRC_PISTACHIO)	+= time-pistachio.o
>  obj-$(CONFIG_CLKSRC_TI_32K)	+= timer-ti-32k.o
>  obj-$(CONFIG_CLKSRC_NPS)	+= timer-nps.o
> diff --git a/drivers/clocksource/mtk_systimer.c b/drivers/clocksource/mtk_systimer.c
> new file mode 100644
> index 0000000..77161bb
> --- /dev/null
> +++ b/drivers/clocksource/mtk_systimer.c
> @@ -0,0 +1,132 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +//
> +//  Copyright (C) 2018 MediaTek Inc.
> +
> +#include <linux/interrupt.h>
> +#include <linux/irqreturn.h>
> +#include <linux/clockchips.h>
> +#include <linux/clocksource.h>
> +#include <linux/io.h>
> +#include "timer-of.h"
> +
> +/* registers */
> +#define STMR_CON                  (0x0)
> +#define STMR_VAL                  (0x4)
> +
> +#define TIMER_REG_CON(to)         (timer_of_base(to) + STMR_CON)
> +#define TIMER_REG_VAL(to)         (timer_of_base(to) + STMR_VAL)
> +
> +/* STMR_CON */
> +#define STMR_CON_EN               BIT(0)
> +#define STMR_CON_IRQ_EN           BIT(1)
> +#define STMR_CON_IRQ_CLR          BIT(4)
> +
> +#define TIMER_SYNC_TICKS          3
> +
> +static void mtk_stmr_reset(struct timer_of *to)
> +{
> +	/* Clear IRQ */
> +	writel(STMR_CON_IRQ_CLR | STMR_CON_EN, TIMER_REG_CON(to));
> +
> +	/* Reset counter */
> +	writel(0, TIMER_REG_VAL(to));
> +
> +	/* Disable timer */
> +	writel(0, TIMER_REG_CON(to));

Wouldn't make sense to clear the interrupt after disabling the timer ?

> +}
> +
> +static void mtk_stmr_ack_irq(struct timer_of *to)
> +{
> +	mtk_stmr_reset(to);
> +}
> +
> +static irqreturn_t mtk_stmr_handler(int irq, void *dev_id)
> +{
> +	struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
> +	struct timer_of *to = to_timer_of(clkevt);
> +
> +	mtk_stmr_ack_irq(to);
> +	clkevt->event_handler(clkevt);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int mtk_stmr_clkevt_next_event(unsigned long ticks,
> +				      struct clock_event_device *clkevt)
> +{
> +	struct timer_of *to = to_timer_of(clkevt);
> +
> +	/*
> +	 * reset timer first because we do not expect interrupt is triggered
> +	 * by old compare value.
> +	 */
> +	mtk_stmr_reset(to);
> +
> +	writel(STMR_CON_EN, TIMER_REG_CON(to));
> +
> +	writel(ticks, TIMER_REG_VAL(to));
> +
> +	writel(STMR_CON_EN | STMR_CON_IRQ_EN, TIMER_REG_CON(to));
> +
> +	return 0;
> +}
> +
> +static int mtk_stmr_clkevt_shutdown(struct clock_event_device *clkevt)
> +{
> +	mtk_stmr_reset(to_timer_of(clkevt));
> +
> +	return 0;
> +}
> +
> +static int mtk_stmr_clkevt_resume(struct clock_event_device *clkevt)
> +{
> +	return mtk_stmr_clkevt_shutdown(clkevt);
> +}
> +
> +static int mtk_stmr_clkevt_oneshot(struct clock_event_device *clkevt)
> +{
> +	return 0;
> +}
> +
> +static struct timer_of to = {
> +	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
> +
> +	.clkevt = {
> +		.name = "mtk-clkevt",
> +		.rating = 300,
> +		.features = CLOCK_EVT_FEAT_DYNIRQ | CLOCK_EVT_FEAT_ONESHOT,
> +		.set_state_shutdown = mtk_stmr_clkevt_shutdown,
> +		.set_state_oneshot = mtk_stmr_clkevt_oneshot,
> +		.tick_resume = mtk_stmr_clkevt_resume,
> +		.set_next_event = mtk_stmr_clkevt_next_event,
> +		.cpumask = cpu_possible_mask,
> +	},
> +
> +	.of_irq = {
> +		.handler = mtk_stmr_handler,
> +		.flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_TRIGGER_HIGH |

Why do you need IRQF_TRIGGER_HIGH ?

> +			 IRQF_PERCPU,

Why IRQF_PERCPU ?

> +	},
> +};
> +
> +static int __init mtk_stmr_init(struct device_node *node)
> +{
> +	int ret;
> +
> +	ret = timer_of_init(node, &to);
> +	if (ret)
> +		return ret;
> +
> +	mtk_stmr_reset(&to);
> +
> +	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
> +					TIMER_SYNC_TICKS, 0xffffffff);
> +
> +	pr_info("mtk_stmr: irq=%d, rate=%lu, max_ns: %llu, min_ns: %llu\n",
> +		timer_of_irq(&to), timer_of_rate(&to),
> +		to.clkevt.max_delta_ns, to.clkevt.min_delta_ns);
> +
> +	return ret;
> +}
> +
> +TIMER_OF_DECLARE(mtk_systimer, "mediatek,sys_timer", mtk_stmr_init);

No "mediatek,sys_timer" but eg. "mediatek,mt6765", so it is consistent
with the DT binding.


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Re: [PATCH v2 1/2] dt-bindings: Add mtk-systimer bindings

[Stanley Chu]

On Wed, 2018-06-27 at 10:20 +0200, Daniel Lezcano wrote:
> Actually this binding already exists for mediatek timers, it is useless
> to add a new one.
> 
> I note the binding in
> 
> Documentation/devicetree/bindings/timer/mediatek,mtk-timer.txt
> 
> contains:
> 
>  clocks = <&system_clk>, <&rtc_clk>
> 
> However the existing driver does only use <&system_clk> AFAICT, I'm
> questioning if <&rtc_clk> is really needed.
> 
> So, I suggest you sort out and fixup the rtc_clk thing (drop it) and
> then just add your new platform in the list in this binding.
> 
> 
Hi Daniel,

OK! We'll fix it and merge two timers into single document file in v3.

Thanks.
Stanley Chu

Re: [PATCH v2 1/2] dt-bindings: Add mtk-systimer bindings

[Stanley Chu]

On Wed, 2018-06-27 at 10:20 +0200, Daniel Lezcano wrote:
> Actually this binding already exists for mediatek timers, it is useless
> to add a new one.
> 
> I note the binding in
> 
> Documentation/devicetree/bindings/timer/mediatek,mtk-timer.txt
> 
> contains:
> 
>  clocks = <&system_clk>, <&rtc_clk>
> 
> However the existing driver does only use <&system_clk> AFAICT, I'm
> questioning if <&rtc_clk> is really needed.
> 
> So, I suggest you sort out and fixup the rtc_clk thing (drop it) and
> then just add your new platform in the list in this binding.
> 
> 
Hi Daniel,

OK! We'll fix it and merge two timers into single document file in v3.

Thanks.
Stanley Chu

Re: [PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Stanley Chu]

On Wed, 2018-06-27 at 12:01 +0200, Daniel Lezcano wrote:
> On 27/06/2018 09:53, Stanley Chu wrote:
> > This patch adds a new clock event for the timer
> > found on the Mediatek SoCs.
> > 
> > The Mediatek System Timer has several 32-bit timers.
> > Only one timer is used by this driver as a clock event
> > supporting oneshot events.
> > 
> > The System Timer can be run with two clocks. A 13 MHz system
> > clock and the RTC clock running at 32 KHz. This implementation
> > uses the system clock with no clock source divider.
> > The interrupts are shared between the different timers.
> > We just enable one interrupt for the clock event. The clock
> > event timer is used by all cores.
> > 
> > Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
> > ---
> >  drivers/clocksource/Kconfig        |   13 +++-
> >  drivers/clocksource/Makefile       |    1 +
> >  drivers/clocksource/mtk_systimer.c |  132 ++++++++++++++++++++++++++++++++++++
> 
> Please merge mtk_systimer.c and mtk_timer.c into a single file:
> 
> timer-mediatek.c
> 
> Patch 1:
> 
>  git mv mtk_timer.c timer-mediatek.c
>  Change the name in Makefile
> 
> Patch 2:
> 
>  Change function prefix name to _gpt_
> 
> Patch 2.1 [optional but recommended] :
> 
>  Move the gpt's init code to timer-of
> 
> Patch 3:
> 
>  Add code for syst in timer-mediatek.c
> 

Thanks for suggestion.
Will do above all in v3.

> 
> 
> A couple of comments below.
> 
> >  3 files changed, 144 insertions(+), 2 deletions(-)
> >  create mode 100644 drivers/clocksource/mtk_systimer.c
> > 
> > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> > index dec0dd8..362c110 100644
> > --- a/drivers/clocksource/Kconfig
> > +++ b/drivers/clocksource/Kconfig
> > @@ -442,12 +442,21 @@ config SYS_SUPPORTS_SH_CMT
> >          bool
> >  
> >  config MTK_TIMER
> > -	bool "Mediatek timer driver" if COMPILE_TEST
> > +	bool "Mediatek general purpose timer driver" if COMPILE_TEST
> >  	depends on HAS_IOMEM
> >  	select TIMER_OF
> >  	select CLKSRC_MMIO
> >  	help
> > -	  Support for Mediatek timer driver.
> > +	  Support for Mediatek General Purpose Timer (GPT) driver.
> > +
> > +config MTK_TIMER_SYSTIMER
> > +	bool "Mediatek system timer driver" if COMPILE_TEST
> > +	depends on HAS_IOMEM
> > +	select TIMER_OF
> > +	select CLKSRC_MMIO
> > +	help
> > +	  Support for Mediatek System Timer (sys_timer) driver used as
> > +	  a clock event supporting oneshot events.
> >  
> >  config SPRD_TIMER
> >  	bool "Spreadtrum timer driver" if EXPERT
> > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> > index 00caf37..cdd34b2 100644
> > --- a/drivers/clocksource/Makefile
> > +++ b/drivers/clocksource/Makefile
> > @@ -50,6 +50,7 @@ obj-$(CONFIG_FSL_FTM_TIMER)	+= fsl_ftm_timer.o
> >  obj-$(CONFIG_VF_PIT_TIMER)	+= vf_pit_timer.o
> >  obj-$(CONFIG_CLKSRC_QCOM)	+= qcom-timer.o
> >  obj-$(CONFIG_MTK_TIMER)		+= mtk_timer.o
> > +obj-$(CONFIG_MTK_TIMER_SYSTIMER)	+= mtk_systimer.o
> >  obj-$(CONFIG_CLKSRC_PISTACHIO)	+= time-pistachio.o
> >  obj-$(CONFIG_CLKSRC_TI_32K)	+= timer-ti-32k.o
> >  obj-$(CONFIG_CLKSRC_NPS)	+= timer-nps.o
> > diff --git a/drivers/clocksource/mtk_systimer.c b/drivers/clocksource/mtk_systimer.c
> > new file mode 100644
> > index 0000000..77161bb
> > --- /dev/null
> > +++ b/drivers/clocksource/mtk_systimer.c
> > @@ -0,0 +1,132 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +//
> > +//  Copyright (C) 2018 MediaTek Inc.
> > +
> > +#include <linux/interrupt.h>
> > +#include <linux/irqreturn.h>
> > +#include <linux/clockchips.h>
> > +#include <linux/clocksource.h>
> > +#include <linux/io.h>
> > +#include "timer-of.h"
> > +
> > +/* registers */
> > +#define STMR_CON                  (0x0)
> > +#define STMR_VAL                  (0x4)
> > +
> > +#define TIMER_REG_CON(to)         (timer_of_base(to) + STMR_CON)
> > +#define TIMER_REG_VAL(to)         (timer_of_base(to) + STMR_VAL)
> > +
> > +/* STMR_CON */
> > +#define STMR_CON_EN               BIT(0)
> > +#define STMR_CON_IRQ_EN           BIT(1)
> > +#define STMR_CON_IRQ_CLR          BIT(4)
> > +
> > +#define TIMER_SYNC_TICKS          3
> > +
> > +static void mtk_stmr_reset(struct timer_of *to)
> > +{
> > +	/* Clear IRQ */
> > +	writel(STMR_CON_IRQ_CLR | STMR_CON_EN, TIMER_REG_CON(to));
> > +
> > +	/* Reset counter */
> > +	writel(0, TIMER_REG_VAL(to));
> > +
> > +	/* Disable timer */
> > +	writel(0, TIMER_REG_CON(to));
> 
> Wouldn't make sense to clear the interrupt after disabling the timer ?
> 
The comment may mislead readers.

The first step, we do both things in the same time,
1. Clear interrupt status.
2. Disable interrupt engine in timer hardware, so the interrupt cannot
come repeatedly.

After that, we shall be safe enough to do followings.

> > +}
> > +
> > +static void mtk_stmr_ack_irq(struct timer_of *to)
> > +{
> > +	mtk_stmr_reset(to);
> > +}
> > +
> > +static irqreturn_t mtk_stmr_handler(int irq, void *dev_id)
> > +{
> > +	struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
> > +	struct timer_of *to = to_timer_of(clkevt);
> > +
> > +	mtk_stmr_ack_irq(to);
> > +	clkevt->event_handler(clkevt);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int mtk_stmr_clkevt_next_event(unsigned long ticks,
> > +				      struct clock_event_device *clkevt)
> > +{
> > +	struct timer_of *to = to_timer_of(clkevt);
> > +
> > +	/*
> > +	 * reset timer first because we do not expect interrupt is triggered
> > +	 * by old compare value.
> > +	 */
> > +	mtk_stmr_reset(to);
> > +
> > +	writel(STMR_CON_EN, TIMER_REG_CON(to));
> > +
> > +	writel(ticks, TIMER_REG_VAL(to));
> > +
> > +	writel(STMR_CON_EN | STMR_CON_IRQ_EN, TIMER_REG_CON(to));
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_stmr_clkevt_shutdown(struct clock_event_device *clkevt)
> > +{
> > +	mtk_stmr_reset(to_timer_of(clkevt));
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_stmr_clkevt_resume(struct clock_event_device *clkevt)
> > +{
> > +	return mtk_stmr_clkevt_shutdown(clkevt);
> > +}
> > +
> > +static int mtk_stmr_clkevt_oneshot(struct clock_event_device *clkevt)
> > +{
> > +	return 0;
> > +}
> > +
> > +static struct timer_of to = {
> > +	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
> > +
> > +	.clkevt = {
> > +		.name = "mtk-clkevt",
> > +		.rating = 300,
> > +		.features = CLOCK_EVT_FEAT_DYNIRQ | CLOCK_EVT_FEAT_ONESHOT,
> > +		.set_state_shutdown = mtk_stmr_clkevt_shutdown,
> > +		.set_state_oneshot = mtk_stmr_clkevt_oneshot,
> > +		.tick_resume = mtk_stmr_clkevt_resume,
> > +		.set_next_event = mtk_stmr_clkevt_next_event,
> > +		.cpumask = cpu_possible_mask,
> > +	},
> > +
> > +	.of_irq = {
> > +		.handler = mtk_stmr_handler,
> > +		.flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_TRIGGER_HIGH |
> 
> Why do you need IRQF_TRIGGER_HIGH ?
> 
> > +			 IRQF_PERCPU,
> 
> Why IRQF_PERCPU ?
> 

Both flags are wrong and will be removed.

> > +	},
> > +};
> > +
> > +static int __init mtk_stmr_init(struct device_node *node)
> > +{
> > +	int ret;
> > +
> > +	ret = timer_of_init(node, &to);
> > +	if (ret)
> > +		return ret;
> > +
> > +	mtk_stmr_reset(&to);
> > +
> > +	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
> > +					TIMER_SYNC_TICKS, 0xffffffff);
> > +
> > +	pr_info("mtk_stmr: irq=%d, rate=%lu, max_ns: %llu, min_ns: %llu\n",
> > +		timer_of_irq(&to), timer_of_rate(&to),
> > +		to.clkevt.max_delta_ns, to.clkevt.min_delta_ns);
> > +
> > +	return ret;
> > +}
> > +
> > +TIMER_OF_DECLARE(mtk_systimer, "mediatek,sys_timer", mtk_stmr_init);
> 
> No "mediatek,sys_timer" but eg. "mediatek,mt6765", so it is consistent
> with the DT binding.

We will sort out bindings of these two timers in v3.

> 
> 

Thanks.
Stanley Chu

Re: [PATCH v2 2/2] clocksource/drivers/mtk_systimer: Add support for Mediatek SoCs

[Stanley Chu]

On Wed, 2018-06-27 at 12:01 +0200, Daniel Lezcano wrote:
> On 27/06/2018 09:53, Stanley Chu wrote:
> > This patch adds a new clock event for the timer
> > found on the Mediatek SoCs.
> > 
> > The Mediatek System Timer has several 32-bit timers.
> > Only one timer is used by this driver as a clock event
> > supporting oneshot events.
> > 
> > The System Timer can be run with two clocks. A 13 MHz system
> > clock and the RTC clock running at 32 KHz. This implementation
> > uses the system clock with no clock source divider.
> > The interrupts are shared between the different timers.
> > We just enable one interrupt for the clock event. The clock
> > event timer is used by all cores.
> > 
> > Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
> > ---
> >  drivers/clocksource/Kconfig        |   13 +++-
> >  drivers/clocksource/Makefile       |    1 +
> >  drivers/clocksource/mtk_systimer.c |  132 ++++++++++++++++++++++++++++++++++++
> 
> Please merge mtk_systimer.c and mtk_timer.c into a single file:
> 
> timer-mediatek.c
> 
> Patch 1:
> 
>  git mv mtk_timer.c timer-mediatek.c
>  Change the name in Makefile
> 
> Patch 2:
> 
>  Change function prefix name to _gpt_
> 
> Patch 2.1 [optional but recommended] :
> 
>  Move the gpt's init code to timer-of
> 
> Patch 3:
> 
>  Add code for syst in timer-mediatek.c
> 

Thanks for suggestion.
Will do above all in v3.

> 
> 
> A couple of comments below.
> 
> >  3 files changed, 144 insertions(+), 2 deletions(-)
> >  create mode 100644 drivers/clocksource/mtk_systimer.c
> > 
> > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> > index dec0dd8..362c110 100644
> > --- a/drivers/clocksource/Kconfig
> > +++ b/drivers/clocksource/Kconfig
> > @@ -442,12 +442,21 @@ config SYS_SUPPORTS_SH_CMT
> >          bool
> >  
> >  config MTK_TIMER
> > -	bool "Mediatek timer driver" if COMPILE_TEST
> > +	bool "Mediatek general purpose timer driver" if COMPILE_TEST
> >  	depends on HAS_IOMEM
> >  	select TIMER_OF
> >  	select CLKSRC_MMIO
> >  	help
> > -	  Support for Mediatek timer driver.
> > +	  Support for Mediatek General Purpose Timer (GPT) driver.
> > +
> > +config MTK_TIMER_SYSTIMER
> > +	bool "Mediatek system timer driver" if COMPILE_TEST
> > +	depends on HAS_IOMEM
> > +	select TIMER_OF
> > +	select CLKSRC_MMIO
> > +	help
> > +	  Support for Mediatek System Timer (sys_timer) driver used as
> > +	  a clock event supporting oneshot events.
> >  
> >  config SPRD_TIMER
> >  	bool "Spreadtrum timer driver" if EXPERT
> > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> > index 00caf37..cdd34b2 100644
> > --- a/drivers/clocksource/Makefile
> > +++ b/drivers/clocksource/Makefile
> > @@ -50,6 +50,7 @@ obj-$(CONFIG_FSL_FTM_TIMER)	+= fsl_ftm_timer.o
> >  obj-$(CONFIG_VF_PIT_TIMER)	+= vf_pit_timer.o
> >  obj-$(CONFIG_CLKSRC_QCOM)	+= qcom-timer.o
> >  obj-$(CONFIG_MTK_TIMER)		+= mtk_timer.o
> > +obj-$(CONFIG_MTK_TIMER_SYSTIMER)	+= mtk_systimer.o
> >  obj-$(CONFIG_CLKSRC_PISTACHIO)	+= time-pistachio.o
> >  obj-$(CONFIG_CLKSRC_TI_32K)	+= timer-ti-32k.o
> >  obj-$(CONFIG_CLKSRC_NPS)	+= timer-nps.o
> > diff --git a/drivers/clocksource/mtk_systimer.c b/drivers/clocksource/mtk_systimer.c
> > new file mode 100644
> > index 0000000..77161bb
> > --- /dev/null
> > +++ b/drivers/clocksource/mtk_systimer.c
> > @@ -0,0 +1,132 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +//
> > +//  Copyright (C) 2018 MediaTek Inc.
> > +
> > +#include <linux/interrupt.h>
> > +#include <linux/irqreturn.h>
> > +#include <linux/clockchips.h>
> > +#include <linux/clocksource.h>
> > +#include <linux/io.h>
> > +#include "timer-of.h"
> > +
> > +/* registers */
> > +#define STMR_CON                  (0x0)
> > +#define STMR_VAL                  (0x4)
> > +
> > +#define TIMER_REG_CON(to)         (timer_of_base(to) + STMR_CON)
> > +#define TIMER_REG_VAL(to)         (timer_of_base(to) + STMR_VAL)
> > +
> > +/* STMR_CON */
> > +#define STMR_CON_EN               BIT(0)
> > +#define STMR_CON_IRQ_EN           BIT(1)
> > +#define STMR_CON_IRQ_CLR          BIT(4)
> > +
> > +#define TIMER_SYNC_TICKS          3
> > +
> > +static void mtk_stmr_reset(struct timer_of *to)
> > +{
> > +	/* Clear IRQ */
> > +	writel(STMR_CON_IRQ_CLR | STMR_CON_EN, TIMER_REG_CON(to));
> > +
> > +	/* Reset counter */
> > +	writel(0, TIMER_REG_VAL(to));
> > +
> > +	/* Disable timer */
> > +	writel(0, TIMER_REG_CON(to));
> 
> Wouldn't make sense to clear the interrupt after disabling the timer ?
> 
The comment may mislead readers.

The first step, we do both things in the same time,
1. Clear interrupt status.
2. Disable interrupt engine in timer hardware, so the interrupt cannot
come repeatedly.

After that, we shall be safe enough to do followings.

> > +}
> > +
> > +static void mtk_stmr_ack_irq(struct timer_of *to)
> > +{
> > +	mtk_stmr_reset(to);
> > +}
> > +
> > +static irqreturn_t mtk_stmr_handler(int irq, void *dev_id)
> > +{
> > +	struct clock_event_device *clkevt = (struct clock_event_device *)dev_id;
> > +	struct timer_of *to = to_timer_of(clkevt);
> > +
> > +	mtk_stmr_ack_irq(to);
> > +	clkevt->event_handler(clkevt);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int mtk_stmr_clkevt_next_event(unsigned long ticks,
> > +				      struct clock_event_device *clkevt)
> > +{
> > +	struct timer_of *to = to_timer_of(clkevt);
> > +
> > +	/*
> > +	 * reset timer first because we do not expect interrupt is triggered
> > +	 * by old compare value.
> > +	 */
> > +	mtk_stmr_reset(to);
> > +
> > +	writel(STMR_CON_EN, TIMER_REG_CON(to));
> > +
> > +	writel(ticks, TIMER_REG_VAL(to));
> > +
> > +	writel(STMR_CON_EN | STMR_CON_IRQ_EN, TIMER_REG_CON(to));
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_stmr_clkevt_shutdown(struct clock_event_device *clkevt)
> > +{
> > +	mtk_stmr_reset(to_timer_of(clkevt));
> > +
> > +	return 0;
> > +}
> > +
> > +static int mtk_stmr_clkevt_resume(struct clock_event_device *clkevt)
> > +{
> > +	return mtk_stmr_clkevt_shutdown(clkevt);
> > +}
> > +
> > +static int mtk_stmr_clkevt_oneshot(struct clock_event_device *clkevt)
> > +{
> > +	return 0;
> > +}
> > +
> > +static struct timer_of to = {
> > +	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
> > +
> > +	.clkevt = {
> > +		.name = "mtk-clkevt",
> > +		.rating = 300,
> > +		.features = CLOCK_EVT_FEAT_DYNIRQ | CLOCK_EVT_FEAT_ONESHOT,
> > +		.set_state_shutdown = mtk_stmr_clkevt_shutdown,
> > +		.set_state_oneshot = mtk_stmr_clkevt_oneshot,
> > +		.tick_resume = mtk_stmr_clkevt_resume,
> > +		.set_next_event = mtk_stmr_clkevt_next_event,
> > +		.cpumask = cpu_possible_mask,
> > +	},
> > +
> > +	.of_irq = {
> > +		.handler = mtk_stmr_handler,
> > +		.flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_TRIGGER_HIGH |
> 
> Why do you need IRQF_TRIGGER_HIGH ?
> 
> > +			 IRQF_PERCPU,
> 
> Why IRQF_PERCPU ?
> 

Both flags are wrong and will be removed.

> > +	},
> > +};
> > +
> > +static int __init mtk_stmr_init(struct device_node *node)
> > +{
> > +	int ret;
> > +
> > +	ret = timer_of_init(node, &to);
> > +	if (ret)
> > +		return ret;
> > +
> > +	mtk_stmr_reset(&to);
> > +
> > +	clockevents_config_and_register(&to.clkevt, timer_of_rate(&to),
> > +					TIMER_SYNC_TICKS, 0xffffffff);
> > +
> > +	pr_info("mtk_stmr: irq=%d, rate=%lu, max_ns: %llu, min_ns: %llu\n",
> > +		timer_of_irq(&to), timer_of_rate(&to),
> > +		to.clkevt.max_delta_ns, to.clkevt.min_delta_ns);
> > +
> > +	return ret;
> > +}
> > +
> > +TIMER_OF_DECLARE(mtk_systimer, "mediatek,sys_timer", mtk_stmr_init);
> 
> No "mediatek,sys_timer" but eg. "mediatek,mt6765", so it is consistent
> with the DT binding.

We will sort out bindings of these two timers in v3.

> 
> 

Thanks.
Stanley Chu