[PATCH v9 0/2] Add the driver for Intel Keem Bay SoC timer block

[PATCH v9 0/2] Add the driver for Intel Keem Bay SoC timer block

[shruthi.sanil]

From: Shruthi Sanil <shruthi.sanil@intel.com>

The timer block supports 1 64-bit free running counter
and 8 32-bit general purpose timers.

Patch 1 holds the device tree binding documentation.
Patch 2 holds the device driver.

This driver is tested on the Keem Bay evaluation module board.

Changes since v8:
- The clockevent stucture has been declared as a global static variable,
  rather than allocating memory using kzalloc during probing.
- Updated the print statement indicating the configuration missing as the FW Bug.
- Updated the comments in the function keembay_timer_isr().
- Updated the dt-binding to remove 'oneOf' as there is only 1 entry.
- Updated the dt-binding description clearly indicating that
  the descrption is about the undelying HW.

Changes since v7:
- Added back the compatible string "intel,keembay-gpt-creg"
  as an enum to the mfd device node in the device tree bindings.
- As the timer is used as a broadcast timer during CPU idle,
  only one timer is needed. Hence updated the driver accordingly
  incorporating the review comments.

Changes since v6:
- Removed the unused compatible string from the mfd device node
  to fix the error thrown by the make dt-binding command.

Changes since v5:
- Created a MFD device for the common configuration register
  in the device tree bindings.
- Updated the timer driver with the MFD framework to access the
  common configuration register.

Changes since v4:
- Updated the description in the device tree bindings.
- Updated the unit address of all the timers and counter
  in the device tree binding.

Changes since v3:
- Update in KConfig file to support COMPILE_TEST for Keem Bay timer.
- Update in device tree bindings to remove status field.
- Update in device tree bindings to remove 64-bit address space for
  the child nodes by using non-empty ranges.

Changes since v2:
- Add multi timer support.
- Update in the device tree binding to support multi timers.
- Code optimization.

Changes since v1:
- Add support for KEEMBAY_TIMER to get selected through Kconfig.platforms.
- Add CLOCK_EVT_FEAT_DYNIRQ as part of clockevent feature.
- Avoid overlapping reg regions across 2 device nodes.
- Simplify 2 device nodes as 1 because both are from same IP block.
- Adapt the driver code according to the new simplified devicetree.

Shruthi Sanil (2):
  dt-bindings: timer: Add bindings for Intel Keem Bay SoC Timer
  clocksource: Add Intel Keem Bay timer support

 .../bindings/timer/intel,keembay-timer.yaml   | 125 ++++++++++
 MAINTAINERS                                   |   6 +
 drivers/clocksource/Kconfig                   |  11 +
 drivers/clocksource/Makefile                  |   1 +
 drivers/clocksource/timer-keembay.c           | 227 ++++++++++++++++++
 5 files changed, 370 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/timer/intel,keembay-timer.yaml
 create mode 100644 drivers/clocksource/timer-keembay.c


base-commit: ffb217a13a2eaf6d5bd974fc83036a53ca69f1e2
-- 
2.17.1

[PATCH v9 1/2] dt-bindings: timer: Add bindings for Intel Keem Bay SoC Timer

[shruthi.sanil]

From: Shruthi Sanil <shruthi.sanil@intel.com>

Add Device Tree bindings for the Timer IP, which can be used as
clocksource and clockevent device in the Intel Keem Bay SoC.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Shruthi Sanil <shruthi.sanil@intel.com>
---
 .../bindings/timer/intel,keembay-timer.yaml   | 125 ++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/timer/intel,keembay-timer.yaml

diff --git a/Documentation/devicetree/bindings/timer/intel,keembay-timer.yaml b/Documentation/devicetree/bindings/timer/intel,keembay-timer.yaml
new file mode 100644
index 000000000000..333f137e39e0
--- /dev/null
+++ b/Documentation/devicetree/bindings/timer/intel,keembay-timer.yaml
@@ -0,0 +1,125 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/timer/intel,keembay-timer.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Intel Keem Bay SoC Timers
+
+maintainers:
+  - Shruthi Sanil <shruthi.sanil@intel.com>
+
+description: |
+  The Intel Keem Bay timer IP supports 1 free running counter and 8 timers.
+  Each timer is capable of generating inividual interrupt.
+  Both the features are enabled through the timer general config register.
+
+  The parent node represents the common general configuration details and
+  the child nodes represents the counter and timers.
+
+properties:
+  compatible:
+    items:
+      - enum:
+          - intel,keembay-gpt-creg
+      - const: simple-mfd
+
+  reg:
+    description: General configuration register address and length.
+    maxItems: 1
+
+  ranges: true
+
+  "#address-cells":
+    const: 1
+
+  "#size-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - ranges
+  - "#address-cells"
+  - "#size-cells"
+
+patternProperties:
+  "^counter@[0-9a-f]+$":
+    description: Properties for Intel Keem Bay counter.
+    type: object
+    properties:
+      compatible:
+        items:
+          - enum:
+              - intel,keembay-counter
+
+      reg:
+        maxItems: 1
+
+      clocks:
+        maxItems: 1
+
+    required:
+      - compatible
+      - reg
+      - clocks
+
+  "^timer@[0-9a-f]+$":
+    description: Properties for Intel Keem Bay timer
+    type: object
+    properties:
+      compatible:
+        items:
+          - enum:
+              - intel,keembay-timer
+
+      reg:
+        maxItems: 1
+
+      interrupts:
+        maxItems: 1
+
+      clocks:
+        maxItems: 1
+
+    required:
+      - compatible
+      - reg
+      - interrupts
+      - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #define KEEM_BAY_A53_TIM
+
+    soc {
+        #address-cells = <0x2>;
+        #size-cells = <0x2>;
+
+        gpt@20331000 {
+            compatible = "intel,keembay-gpt-creg", "simple-mfd";
+            reg = <0x0 0x20331000 0x0 0xc>;
+            ranges = <0x0 0x0 0x20330000 0xF0>;
+            #address-cells = <0x1>;
+            #size-cells = <0x1>;
+
+            counter@e8 {
+                compatible = "intel,keembay-counter";
+                reg = <0xe8 0x8>;
+                clocks = <&scmi_clk KEEM_BAY_A53_TIM>;
+            };
+
+            timer@30 {
+                compatible = "intel,keembay-timer";
+                reg = <0x30 0xc>;
+                interrupts = <GIC_SPI 0x5 IRQ_TYPE_LEVEL_HIGH>;
+                clocks = <&scmi_clk KEEM_BAY_A53_TIM>;
+            };
+        };
+    };
+
+...
-- 
2.17.1

[PATCH v9 2/2] clocksource: Add Intel Keem Bay timer support

[shruthi.sanil]

From: Shruthi Sanil <shruthi.sanil@intel.com>

The Intel Keem Bay timer driver supports clocksource and clockevent
features for the timer IP used in Intel Keem Bay SoC.
The timer block supports 1 free running counter and 8 timers.
The free running counter can be used as a clocksource and
the timers can be used as clockevent. Each timer is capable of
generating individual interrupt.
Both the features are enabled through the timer general config register.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Shruthi Sanil <shruthi.sanil@intel.com>
---
 MAINTAINERS                         |   6 +
 drivers/clocksource/Kconfig         |  11 ++
 drivers/clocksource/Makefile        |   1 +
 drivers/clocksource/timer-keembay.c | 227 ++++++++++++++++++++++++++++
 4 files changed, 245 insertions(+)
 create mode 100644 drivers/clocksource/timer-keembay.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 05fd080b82f3..90af9439d529 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9791,6 +9791,12 @@ F:	drivers/crypto/keembay/keembay-ocs-hcu-core.c
 F:	drivers/crypto/keembay/ocs-hcu.c
 F:	drivers/crypto/keembay/ocs-hcu.h
 
+INTEL KEEM BAY TIMER DRIVER
+M:	Shruthi Sanil <shruthi.sanil@intel.com>
+S:	Maintained
+F:	Documentation/devicetree/bindings/timer/intel,keembay-timer.yaml
+F:	drivers/clocksource/timer-keembay.c
+
 INTEL THUNDER BAY EMMC PHY DRIVER
 M:	Nandhini Srikandan <nandhini.srikandan@intel.com>
 M:	Rashmi A <rashmi.a@intel.com>
diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index cfb8ea0df3b1..65b6cf916e5a 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -721,4 +721,15 @@ config MICROCHIP_PIT64B
 	  modes and high resolution. It is used as a clocksource
 	  and a clockevent.
 
+config KEEMBAY_TIMER
+	bool "Intel Keem Bay timer"
+	depends on ARCH_KEEMBAY || COMPILE_TEST
+	select TIMER_OF
+	help
+	  This option enables the support for the Intel Keem Bay
+	  general purpose timer and free running counter driver.
+	  Each timer can generate an individual interrupt and
+	  supports oneshot and periodic modes.
+	  The 64-bit counter can be used as a clock source.
+
 endmenu
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index fa5f624eadb6..dff6458ef9e5 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -89,3 +89,4 @@ obj-$(CONFIG_GX6605S_TIMER)		+= timer-gx6605s.o
 obj-$(CONFIG_HYPERV_TIMER)		+= hyperv_timer.o
 obj-$(CONFIG_MICROCHIP_PIT64B)		+= timer-microchip-pit64b.o
 obj-$(CONFIG_MSC313E_TIMER)		+= timer-msc313e.o
+obj-$(CONFIG_KEEMBAY_TIMER)		+= timer-keembay.o
diff --git a/drivers/clocksource/timer-keembay.c b/drivers/clocksource/timer-keembay.c
new file mode 100644
index 000000000000..385863c064cd
--- /dev/null
+++ b/drivers/clocksource/timer-keembay.c
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Intel Keem Bay Timer driver
+ *
+ * Copyright (C) 2020 Intel Corporation
+ */
+
+#include <linux/bitops.h>
+#include <linux/interrupt.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_address.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/regmap.h>
+
+#include "timer-of.h"
+
+/* Timer register offset */
+#define TIM_CNT_VAL_OFFSET		0x0
+#define TIM_RELOAD_VAL_OFFSET		0x4
+#define TIM_CONFIG_OFFSET		0x8
+
+/* Bit fields of timer general config register */
+#define TIM_CONFIG_PRESCALER_ENABLE	BIT(2)
+#define TIM_CONFIG_COUNTER_ENABLE	BIT(0)
+
+/* Bit fields of timer config register */
+#define TIM_CONFIG_INTERRUPT_PENDING	BIT(4)
+#define TIM_CONFIG_INTERRUPT_ENABLE	BIT(2)
+#define TIM_CONFIG_RESTART		BIT(1)
+#define TIM_CONFIG_ENABLE		BIT(0)
+
+#define TIM_GEN_MASK			GENMASK(31, 12)
+#define TIM_RATING			200
+#define TIM_CLKSRC_MASK_BITS		64
+
+#define TIMER_NAME_SIZE			25
+
+static inline void keembay_timer_enable(void __iomem *base, u32 flags)
+{
+	writel(TIM_CONFIG_ENABLE | flags, base + TIM_CONFIG_OFFSET);
+}
+
+static inline void keembay_timer_disable(void __iomem *base)
+{
+	writel(0x0, base + TIM_CONFIG_OFFSET);
+}
+
+static inline void keembay_timer_update_counter(void __iomem *base, u32 val)
+{
+	writel(val, base + TIM_CNT_VAL_OFFSET);
+	writel(val, base + TIM_RELOAD_VAL_OFFSET);
+}
+
+static inline void keembay_timer_clear_pending_int(void __iomem *base)
+{
+	u32 val;
+
+	val = readl(base + TIM_CONFIG_OFFSET);
+	val &= ~TIM_CONFIG_INTERRUPT_PENDING;
+	writel(val, base + TIM_CONFIG_OFFSET);
+}
+
+static int keembay_timer_set_next_event(unsigned long evt, struct clock_event_device *ce)
+{
+	u32 flags = TIM_CONFIG_INTERRUPT_ENABLE;
+	struct timer_of *to = to_timer_of(ce);
+	void __iomem *tim_base = timer_of_base(to);
+
+	keembay_timer_disable(tim_base);
+	keembay_timer_update_counter(tim_base, evt);
+	keembay_timer_enable(tim_base, flags);
+
+	return 0;
+}
+
+static int keembay_timer_periodic(struct clock_event_device *ce)
+{
+	u32 flags = TIM_CONFIG_INTERRUPT_ENABLE | TIM_CONFIG_RESTART;
+	struct timer_of *to = to_timer_of(ce);
+	void __iomem *tim_base = timer_of_base(to);
+
+	keembay_timer_disable(tim_base);
+	keembay_timer_update_counter(tim_base, timer_of_period(to));
+	keembay_timer_enable(tim_base, flags);
+
+	return 0;
+}
+
+static int keembay_timer_shutdown(struct clock_event_device *ce)
+{
+	struct timer_of *to = to_timer_of(ce);
+
+	keembay_timer_disable(timer_of_base(to));
+
+	return 0;
+}
+
+static irqreturn_t keembay_timer_isr(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = dev_id;
+	struct timer_of *to = to_timer_of(evt);
+	void __iomem *tim_base = timer_of_base(to);
+	u32 val;
+
+	val = readl(tim_base + TIM_CONFIG_OFFSET);
+
+	if (val & TIM_CONFIG_RESTART) {
+		/* Periodic Timer */
+		keembay_timer_clear_pending_int(tim_base);
+	} else {
+		/* One-Shot Timer */
+		keembay_timer_disable(tim_base);
+	}
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static struct timer_of keembay_ce_to = {
+	.flags = TIMER_OF_IRQ | TIMER_OF_BASE | TIMER_OF_CLOCK,
+	.clkevt = {
+		.name		    = "keembay_sys_clkevt",
+		.cpumask	    = cpu_possible_mask,
+		.features	    = CLOCK_EVT_FEAT_PERIODIC |
+				      CLOCK_EVT_FEAT_ONESHOT  |
+				      CLOCK_EVT_FEAT_DYNIRQ,
+		.rating		    = TIM_RATING,
+		.set_next_event	    = keembay_timer_set_next_event,
+		.set_state_periodic = keembay_timer_periodic,
+		.set_state_shutdown = keembay_timer_shutdown,
+	},
+	.of_irq = {
+		.handler = keembay_timer_isr,
+		.flags   = IRQF_TIMER,
+	},
+};
+
+static int __init keembay_clockevent_init(struct device_node *np)
+{
+	struct regmap *regmap;
+	int ret;
+	u32 val;
+
+	regmap = device_node_to_regmap(np->parent);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ret = regmap_read(regmap, TIM_CONFIG_OFFSET, &val);
+	if (ret)
+		return ret;
+
+	/* Prescaler bit must be enabled for the timer to function */
+	if (!(val & TIM_CONFIG_PRESCALER_ENABLE)) {
+		pr_err("%pOF: FW_BUG: Prescaler is not enabled\n", np);
+		ret = -ENODEV;
+	}
+
+
+	ret = timer_of_init(np, &keembay_ce_to);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(regmap, TIM_RELOAD_VAL_OFFSET, &val);
+	if (ret)
+		return ret;
+
+	keembay_ce_to.of_clk.rate = keembay_ce_to.of_clk.rate / (val + 1);
+
+	clockevents_config_and_register(&keembay_ce_to.clkevt,
+					timer_of_rate(&keembay_ce_to),
+					1,
+					U32_MAX);
+
+	return 0;
+}
+
+static struct timer_of keembay_cs_to = {
+	.flags	= TIMER_OF_BASE | TIMER_OF_CLOCK,
+};
+
+static u64 notrace keembay_clocksource_read(struct clocksource *cs)
+{
+	return lo_hi_readq(timer_of_base(&keembay_cs_to));
+}
+
+static struct clocksource keembay_counter = {
+	.name	= "keembay_sys_counter",
+	.rating	= TIM_RATING,
+	.read	= keembay_clocksource_read,
+	.mask	= CLOCKSOURCE_MASK(TIM_CLKSRC_MASK_BITS),
+	.flags	= CLOCK_SOURCE_IS_CONTINUOUS |
+		  CLOCK_SOURCE_SUSPEND_NONSTOP,
+};
+
+static int __init keembay_clocksource_init(struct device_node *np)
+{
+	struct regmap *regmap;
+	u32 val;
+	int ret;
+
+	regmap = device_node_to_regmap(np->parent);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	ret = regmap_read(regmap, TIM_CONFIG_OFFSET, &val);
+	if (ret)
+		return ret;
+
+	/* Free Running Counter bit must be enabled for counter to function */
+	if (!(val & TIM_CONFIG_COUNTER_ENABLE)) {
+		pr_err("%pOF: FW_BUG: free running counter is not enabled\n", np);
+		return -ENODEV;
+	}
+
+	ret = timer_of_init(np, &keembay_cs_to);
+	if (ret)
+		return ret;
+
+	return clocksource_register_hz(&keembay_counter, timer_of_rate(&keembay_cs_to));
+}
+
+TIMER_OF_DECLARE(keembay_clockevent, "intel,keembay-timer", keembay_clockevent_init);
+TIMER_OF_DECLARE(keembay_clocksource, "intel,keembay-counter", keembay_clocksource_init);
-- 
2.17.1

Re: [PATCH v9 2/2] clocksource: Add Intel Keem Bay timer support

[Andy Shevchenko]

On Mon, Mar 07, 2022 at 05:01:47PM +0530, shruthi.sanil@intel.com wrote:
> From: Shruthi Sanil <shruthi.sanil@intel.com>
> 
> The Intel Keem Bay timer driver supports clocksource and clockevent
> features for the timer IP used in Intel Keem Bay SoC.
> The timer block supports 1 free running counter and 8 timers.
> The free running counter can be used as a clocksource and
> the timers can be used as clockevent. Each timer is capable of
> generating individual interrupt.
> Both the features are enabled through the timer general config register.

...

> +		pr_err("%pOF: FW_BUG: Prescaler is not enabled\n", np);

FW_BUG is a macro. The above is an incorrect use of it.

...

> +		pr_err("%pOF: FW_BUG: free running counter is not enabled\n", np);

Ditto.

-- 
With Best Regards,
Andy Shevchenko

RE: [PATCH v9 2/2] clocksource: Add Intel Keem Bay timer support

[Sanil, Shruthi]

> -----Original Message-----
> From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Sent: Monday, March 7, 2022 7:15 PM
> To: Sanil, Shruthi <shruthi.sanil@intel.com>
> Cc: daniel.lezcano@linaro.org; tglx@linutronix.de; robh+dt@kernel.org;
> linux-kernel@vger.kernel.org; devicetree@vger.kernel.org;
> mgross@linux.intel.com; Thokala, Srikanth <srikanth.thokala@intel.com>;
> Raja Subramanian, Lakshmi Bai <lakshmi.bai.raja.subramanian@intel.com>;
> Sangannavar, Mallikarjunappa <mallikarjunappa.sangannavar@intel.com>
> Subject: Re: [PATCH v9 2/2] clocksource: Add Intel Keem Bay timer support
> 
> On Mon, Mar 07, 2022 at 05:01:47PM +0530, shruthi.sanil@intel.com wrote:
> > From: Shruthi Sanil <shruthi.sanil@intel.com>
> >
> > The Intel Keem Bay timer driver supports clocksource and clockevent
> > features for the timer IP used in Intel Keem Bay SoC.
> > The timer block supports 1 free running counter and 8 timers.
> > The free running counter can be used as a clocksource and the timers
> > can be used as clockevent. Each timer is capable of generating
> > individual interrupt.
> > Both the features are enabled through the timer general config register.
> 
> ...
> 
> > +		pr_err("%pOF: FW_BUG: Prescaler is not enabled\n", np);
> 
> FW_BUG is a macro. The above is an incorrect use of it.

Oh! I'll correct it and send the updated patch.

> 
> ...
> 
> > +		pr_err("%pOF: FW_BUG: free running counter is not
> enabled\n", np);
> 
> Ditto.
> 
> --
> With Best Regards,
> Andy Shevchenko
> 

Re: [PATCH v9 2/2] clocksource: Add Intel Keem Bay timer support

[Daniel Lezcano]

On 07/03/2022 12:31, shruthi.sanil@intel.com wrote:
> From: Shruthi Sanil <shruthi.sanil@intel.com>

[ ... ]

> +	/* Prescaler bit must be enabled for the timer to function */
> +	if (!(val & TIM_CONFIG_PRESCALER_ENABLE)) {
> +		pr_err("%pOF: FW_BUG: Prescaler is not enabled\n", np);
> +		ret = -ENODEV;

		return -ENODEV;

> +	}

[ ... ]

FW_BUG macro comment was already spotted

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