[PATCH v3 0/5] Reintroduce i.MX EPIT Timer

[PATCH v3 0/5] Reintroduce i.MX EPIT Timer

[Clément Péron]

From: Clément Peron <clement.peron@devialet.com>

As suggested in the commit message we have added the device tree support,
proper bindings and we moved the driver into the correct folder.

Moreover we made some changes like use of relaxed IO accesor,
implement sched_clock, delay_timer and reduce the clockevents min_delta.

Changes since v2 (Thanks Fabio Estevam):
- Removed unused "ckil" clock
- Add out_iounmap
- Check and handle if clk_prepare_enable failed
- Fix comment typo

Changes since v1 (Thanks Vladimir Zapolskiy):
- Add OF dependency in Kconfig
- Sort header
- Use BIT macro
- Remove useless comments
- Fix incorrect indent
- Fix memory leak
- Add check and handle possible returned error

Clément Peron (2):
  ARM: imx: remove inexistant EPIT timer init
  Documentation: DT: add i.MX EPIT timer binding

Colin Didier (3):
  clk: imx6: add EPIT clock support
  clocksource: add driver for i.MX EPIT timer
  ARM: dts: imx6qdl: add missing compatible and clock properties for
    EPIT

 .../devicetree/bindings/clock/imx6q,epit.txt  |  24 ++
 arch/arm/boot/dts/imx6qdl.dtsi                |  10 +
 arch/arm/mach-imx/common.h                    |   1 -
 drivers/clk/imx/clk-imx6q.c                   |   2 +
 drivers/clocksource/Kconfig                   |  12 +
 drivers/clocksource/Makefile                  |   1 +
 drivers/clocksource/timer-imx-epit.c          | 283 ++++++++++++++++++
 include/dt-bindings/clock/imx6qdl-clock.h     |   4 +-
 8 files changed, 335 insertions(+), 2 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/clock/imx6q,epit.txt
 create mode 100644 drivers/clocksource/timer-imx-epit.c

-- 
2.17.0


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[PATCH v3 1/5] ARM: imx: remove inexistant EPIT timer init

[Clément Péron]

From: Clément Peron <clement.peron@devialet.com>

i.MX EPIT timer has been removed but not the init function declaration.

Signed-off-by: Clément Peron <clement.peron@devialet.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
---
 arch/arm/mach-imx/common.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/arm/mach-imx/common.h b/arch/arm/mach-imx/common.h
index c8d68e918b2f..18aae76fa2da 100644
--- a/arch/arm/mach-imx/common.h
+++ b/arch/arm/mach-imx/common.h
@@ -38,7 +38,6 @@ void imx21_soc_init(void);
 void imx27_soc_init(void);
 void imx31_soc_init(void);
 void imx35_soc_init(void);
-void epit_timer_init(void __iomem *base, int irq);
 int mx21_clocks_init(unsigned long lref, unsigned long fref);
 int mx27_clocks_init(unsigned long fref);
 int mx31_clocks_init(unsigned long fref);
-- 
2.17.0


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[PATCH v3 2/5] clk: imx6: add EPIT clock support

[Clément Péron]

From: Colin Didier <colin.didier@devialet.com>

Add EPIT clock support to the i.MX6Q clocking infrastructure.

Signed-off-by: Colin Didier <colin.didier@devialet.com>
Signed-off-by: Clément Peron <clement.peron@devialet.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
---
 drivers/clk/imx/clk-imx6q.c               | 2 ++
 include/dt-bindings/clock/imx6qdl-clock.h | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/imx/clk-imx6q.c b/drivers/clk/imx/clk-imx6q.c
index 8d518ad5dc13..b9ea7037e193 100644
--- a/drivers/clk/imx/clk-imx6q.c
+++ b/drivers/clk/imx/clk-imx6q.c
@@ -753,6 +753,8 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	else
 		clk[IMX6Q_CLK_ECSPI5] = imx_clk_gate2("ecspi5",        "ecspi_root",        base + 0x6c, 8);
 	clk[IMX6QDL_CLK_ENET]         = imx_clk_gate2("enet",          "ipg",               base + 0x6c, 10);
+	clk[IMX6QDL_CLK_EPIT1]        = imx_clk_gate2("epit1",         "ipg",               base + 0x6c, 12);
+	clk[IMX6QDL_CLK_EPIT2]        = imx_clk_gate2("epit2",         "ipg",               base + 0x6c, 14);
 	clk[IMX6QDL_CLK_ESAI_EXTAL]   = imx_clk_gate2_shared("esai_extal",   "esai_podf",   base + 0x6c, 16, &share_count_esai);
 	clk[IMX6QDL_CLK_ESAI_IPG]     = imx_clk_gate2_shared("esai_ipg",   "ahb",           base + 0x6c, 16, &share_count_esai);
 	clk[IMX6QDL_CLK_ESAI_MEM]     = imx_clk_gate2_shared("esai_mem", "ahb",             base + 0x6c, 16, &share_count_esai);
diff --git a/include/dt-bindings/clock/imx6qdl-clock.h b/include/dt-bindings/clock/imx6qdl-clock.h
index da59fd9cdb5e..7ad171b8f3bf 100644
--- a/include/dt-bindings/clock/imx6qdl-clock.h
+++ b/include/dt-bindings/clock/imx6qdl-clock.h
@@ -271,6 +271,8 @@
 #define IMX6QDL_CLK_PRE_AXI			258
 #define IMX6QDL_CLK_MLB_SEL			259
 #define IMX6QDL_CLK_MLB_PODF			260
-#define IMX6QDL_CLK_END				261
+#define IMX6QDL_CLK_EPIT1			261
+#define IMX6QDL_CLK_EPIT2			262
+#define IMX6QDL_CLK_END				263
 
 #endif /* __DT_BINDINGS_CLOCK_IMX6QDL_H */
-- 
2.17.0


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[PATCH v3 3/5] Documentation: DT: add i.MX EPIT timer binding

[Clément Péron]

From: Clément Peron <clement.peron@devialet.com>

Add devicetree binding document for NXP's i.MX SoC specific
EPIT timer driver.

Signed-off-by: Clément Peron <clement.peron@devialet.com>
---
 .../devicetree/bindings/clock/imx6q,epit.txt  | 24 +++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/clock/imx6q,epit.txt

diff --git a/Documentation/devicetree/bindings/clock/imx6q,epit.txt b/Documentation/devicetree/bindings/clock/imx6q,epit.txt
new file mode 100644
index 000000000000..a84a60c6ae35
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/imx6q,epit.txt
@@ -0,0 +1,24 @@
+Binding for the i.MX6 EPIT timer
+
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible: should be "fsl,imx6q-epit"
+- reg: physical base address of the controller and length of memory mapped
+  region.
+- interrupts: Should contain EPIT controller interrupt
+- clocks: list of clock specifiers, must contain an entry for each required
+  entry in clock-names
+- clock-names : should include entries "ipg", "per"
+
+Example:
+	epit1: epit@20d0000 {
+		compatible = "fsl,imx6q-epit";
+		reg = <0x020d0000 0x4000>;
+		interrupts = <0 56 IRQ_TYPE_LEVEL_HIGH>;
+		clocks = <&clks IMX6QDL_CLK_EPIT1>,
+			<&clks IMX6QDL_CLK_IPG_PER>;
+		clock-names = "ipg", "per";
+	};
-- 
2.17.0


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[PATCH v3 4/5] clocksource: add driver for i.MX EPIT timer

[Clément Péron]

From: Colin Didier <colin.didier@devialet.com>

Add driver for NXP's EPIT timer used in i.MX 6 family of SoC.

Signed-off-by: Colin Didier <colin.didier@devialet.com>
Signed-off-by: Clément Peron <clement.peron@devialet.com>
---
 drivers/clocksource/Kconfig          |  12 ++
 drivers/clocksource/Makefile         |   1 +
 drivers/clocksource/timer-imx-epit.c | 283 +++++++++++++++++++++++++++
 3 files changed, 296 insertions(+)
 create mode 100644 drivers/clocksource/timer-imx-epit.c

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 8e8a09755d10..920a0874f3a4 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -576,6 +576,18 @@ config H8300_TPU
 	  This enables the clocksource for the H8300 platform with the
 	  H8S2678 cpu.
 
+config CLKSRC_IMX_EPIT
+	bool "Clocksource using i.MX EPIT"
+	depends on ARM && CLKDEV_LOOKUP && OF && (ARCH_MXC || COMPILE_TEST)
+	select TIMER_OF
+	select CLKSRC_MMIO
+	help
+	  This enables EPIT support available on some i.MX platforms.
+	  Normally you don't have a reason to do so as the EPIT has
+	  the same features and uses the same clocks as the GPT.
+	  Anyway, on some systems the GPT may be in use for other
+	  purposes.
+
 config CLKSRC_IMX_GPT
 	bool "Clocksource using i.MX GPT" if COMPILE_TEST
 	depends on ARM && CLKDEV_LOOKUP
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index 00caf37e52f9..d9426f69ec69 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_INTEGRATOR_AP_TIMER)	+= timer-integrator-ap.o
 obj-$(CONFIG_CLKSRC_VERSATILE)		+= versatile.o
 obj-$(CONFIG_CLKSRC_MIPS_GIC)		+= mips-gic-timer.o
 obj-$(CONFIG_CLKSRC_TANGO_XTAL)		+= tango_xtal.o
+obj-$(CONFIG_CLKSRC_IMX_EPIT)		+= timer-imx-epit.o
 obj-$(CONFIG_CLKSRC_IMX_GPT)		+= timer-imx-gpt.o
 obj-$(CONFIG_CLKSRC_IMX_TPM)		+= timer-imx-tpm.o
 obj-$(CONFIG_ASM9260_TIMER)		+= asm9260_timer.o
diff --git a/drivers/clocksource/timer-imx-epit.c b/drivers/clocksource/timer-imx-epit.c
new file mode 100644
index 000000000000..87025d5f3a97
--- /dev/null
+++ b/drivers/clocksource/timer-imx-epit.c
@@ -0,0 +1,283 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * i.MX EPIT Timer
+ *
+ * Copyright (C) 2010 Sascha Hauer <s.hauer@pengutronix.de>
+ * Copyright (C) 2018 Colin Didier <colin.didier@devialet.com>
+ * Copyright (C) 2018 Clément Péron <clement.peron@devialet.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+
+#define EPITCR				0x00
+#define EPITSR				0x04
+#define EPITLR				0x08
+#define EPITCMPR			0x0c
+#define EPITCNR				0x10
+
+#define EPITCR_EN			BIT(0)
+#define EPITCR_ENMOD			BIT(1)
+#define EPITCR_OCIEN			BIT(2)
+#define EPITCR_RLD			BIT(3)
+#define EPITCR_PRESC(x)			(((x) & 0xfff) << 4)
+#define EPITCR_SWR			BIT(16)
+#define EPITCR_IOVW			BIT(17)
+#define EPITCR_DBGEN			BIT(18)
+#define EPITCR_WAITEN			BIT(19)
+#define EPITCR_RES			BIT(20)
+#define EPITCR_STOPEN			BIT(21)
+#define EPITCR_OM_DISCON		(0 << 22)
+#define EPITCR_OM_TOGGLE		(1 << 22)
+#define EPITCR_OM_CLEAR			(2 << 22)
+#define EPITCR_OM_SET			(3 << 22)
+#define EPITCR_CLKSRC_OFF		(0 << 24)
+#define EPITCR_CLKSRC_PERIPHERAL	(1 << 24)
+#define EPITCR_CLKSRC_REF_HIGH		(2 << 24)
+#define EPITCR_CLKSRC_REF_LOW		(3 << 24)
+
+#define EPITSR_OCIF			BIT(0)
+
+struct epit_timer {
+	void __iomem *base;
+	int irq;
+	struct clk *clk_per;
+	struct clock_event_device ced;
+	struct irqaction act;
+};
+
+static void __iomem *sched_clock_reg;
+
+static inline struct epit_timer *to_epit_timer(struct clock_event_device *ced)
+{
+	return container_of(ced, struct epit_timer, ced);
+}
+
+static inline void epit_irq_disable(struct epit_timer *epittm)
+{
+	u32 val;
+
+	val = readl_relaxed(epittm->base + EPITCR);
+	writel_relaxed(val & ~EPITCR_OCIEN, epittm->base + EPITCR);
+}
+
+static inline void epit_irq_enable(struct epit_timer *epittm)
+{
+	u32 val;
+
+	val = readl_relaxed(epittm->base + EPITCR);
+	writel_relaxed(val | EPITCR_OCIEN, epittm->base + EPITCR);
+}
+
+static void epit_irq_acknowledge(struct epit_timer *epittm)
+{
+	writel_relaxed(EPITSR_OCIF, epittm->base + EPITSR);
+}
+
+static u64 notrace epit_read_sched_clock(void)
+{
+	return ~readl_relaxed(sched_clock_reg);
+}
+
+static int __init epit_clocksource_init(struct epit_timer *epittm)
+{
+	unsigned int c = clk_get_rate(epittm->clk_per);
+
+	sched_clock_reg = epittm->base + EPITCNR;
+	sched_clock_register(epit_read_sched_clock, 32, c);
+
+	return clocksource_mmio_init(epittm->base + EPITCNR, "epit", c, 200, 32,
+			clocksource_mmio_readl_down);
+}
+
+static int epit_set_next_event(unsigned long cycles,
+			       struct clock_event_device *ced)
+{
+	struct epit_timer *epittm = to_epit_timer(ced);
+	unsigned long tcmp;
+
+	tcmp = readl_relaxed(epittm->base + EPITCNR) - cycles;
+	writel_relaxed(tcmp, epittm->base + EPITCMPR);
+
+	return 0;
+}
+
+/* Left event sources disabled, no more interrupts appear */
+static int epit_shutdown(struct clock_event_device *ced)
+{
+	struct epit_timer *epittm = to_epit_timer(ced);
+	unsigned long flags;
+
+	/*
+	 * The timer interrupt generation is disabled at least
+	 * for enough time to call epit_set_next_event()
+	 */
+	local_irq_save(flags);
+
+	/* Disable interrupt in EPIT module */
+	epit_irq_disable(epittm);
+
+	/* Clear pending interrupt */
+	epit_irq_acknowledge(epittm);
+
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+static int epit_set_oneshot(struct clock_event_device *ced)
+{
+	struct epit_timer *epittm = to_epit_timer(ced);
+	unsigned long flags;
+
+	/*
+	 * The timer interrupt generation is disabled at least
+	 * for enough time to call epit_set_next_event()
+	 */
+	local_irq_save(flags);
+
+	/* Disable interrupt in EPIT module */
+	epit_irq_disable(epittm);
+
+	/* Clear pending interrupt, only while switching mode */
+	if (!clockevent_state_oneshot(ced))
+		epit_irq_acknowledge(epittm);
+
+	/*
+	 * Do not put overhead of interrupt enable/disable into
+	 * epit_set_next_event(), the core has about 4 minutes
+	 * to call epit_set_next_event() or shutdown clock after
+	 * mode switching
+	 */
+	epit_irq_enable(epittm);
+	local_irq_restore(flags);
+
+	return 0;
+}
+
+static irqreturn_t epit_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *ced = dev_id;
+	struct epit_timer *epittm = to_epit_timer(ced);
+
+	epit_irq_acknowledge(epittm);
+
+	ced->event_handler(ced);
+
+	return IRQ_HANDLED;
+}
+
+static int __init epit_clockevent_init(struct epit_timer *epittm)
+{
+	struct clock_event_device *ced = &epittm->ced;
+	struct irqaction *act = &epittm->act;
+
+	ced->name = "epit";
+	ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_DYNIRQ;
+	ced->set_state_shutdown = epit_shutdown;
+	ced->tick_resume = epit_shutdown;
+	ced->set_state_oneshot = epit_set_oneshot;
+	ced->set_next_event = epit_set_next_event;
+	ced->rating = 200;
+	ced->cpumask = cpumask_of(0);
+	ced->irq = epittm->irq;
+	clockevents_config_and_register(ced, clk_get_rate(epittm->clk_per),
+		0xff, 0xfffffffe);
+
+	act->name = "i.MX EPIT Timer Tick",
+	act->flags = IRQF_TIMER | IRQF_IRQPOLL;
+	act->handler = epit_timer_interrupt;
+	act->dev_id = ced;
+
+	/* Make irqs happen */
+	return setup_irq(epittm->irq, act);
+}
+
+static int __init epit_timer_init(struct device_node *np)
+{
+	struct epit_timer *epittm;
+	struct clk *clk_ipg;
+	int ret;
+
+	epittm = kzalloc(sizeof(*epittm), GFP_KERNEL);
+	if (!epittm)
+		return -ENOMEM;
+
+	epittm->base = of_iomap(np, 0);
+	if (!epittm->base) {
+		ret = -ENXIO;
+		goto out_kfree;
+	}
+
+	epittm->irq = irq_of_parse_and_map(np, 0);
+	if (!epittm->irq) {
+		ret = -EINVAL;
+		goto out_iounmap;
+	}
+
+	clk_ipg = of_clk_get_by_name(np, "ipg");
+	if (IS_ERR(clk_ipg)) {
+		pr_err("i.MX EPIT: unable to get clk_ipg\n");
+		ret = PTR_ERR(clk_ipg);
+		goto out_iounmap;
+	}
+
+	ret = clk_prepare_enable(clk_ipg);
+	if (ret) {
+		pr_err("i.MX EPIT: unable to prepare+enable clk_ipg\n");
+		goto out_clk_ipg_disable;
+	}
+
+	epittm->clk_per = of_clk_get_by_name(np, "per");
+	if (IS_ERR(epittm->clk_per)) {
+		pr_err("i.MX EPIT: unable to get clk_per\n");
+		ret = PTR_ERR(epittm->clk_per);
+		goto out_clk_ipg_disable;
+	}
+
+	ret = clk_prepare_enable(epittm->clk_per);
+	if (ret) {
+		pr_err("i.MX EPIT: unable to prepare+enable clk_per\n");
+		goto out_clk_ipg_disable;
+	}
+
+	/* Initialise to a known state (all timers off, and timing reset) */
+	writel_relaxed(0x0, epittm->base + EPITCR);
+	writel_relaxed(0xffffffff, epittm->base + EPITLR);
+	writel_relaxed(EPITCR_EN | EPITCR_CLKSRC_REF_HIGH | EPITCR_WAITEN,
+		       epittm->base + EPITCR);
+
+	ret = epit_clocksource_init(epittm);
+	if(ret) {
+		pr_err("i.MX EPIT: failed to init clocksource\n");
+		goto out_clk_per_disable;
+	}
+
+	ret = epit_clockevent_init(epittm);
+	if(ret) {
+		pr_err("i.MX EPIT: failed to init clockevent\n");
+		goto out_clk_per_disable;
+	}
+
+	return 0;
+
+out_clk_per_disable:
+	clk_disable_unprepare(epittm->clk_per);
+out_clk_ipg_disable:
+	clk_disable_unprepare(clk_ipg);
+out_iounmap:
+	iounmap(epittm->base);
+out_kfree:
+	kfree(epittm);
+
+	return ret;
+}
+TIMER_OF_DECLARE(mx6q_timer, "fsl,imx6q-epit", epit_timer_init);
-- 
2.17.0


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[PATCH v3 5/5] ARM: dts: imx6qdl: add missing compatible and clock properties for EPIT

[Clément Péron]

From: Colin Didier <colin.didier@devialet.com>

Add missing compatible and clock properties for EPIT node.

Signed-off-by: Colin Didier <colin.didier@devialet.com>
Signed-off-by: Clément Peron <clement.peron@devialet.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
---
 arch/arm/boot/dts/imx6qdl.dtsi | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm/boot/dts/imx6qdl.dtsi b/arch/arm/boot/dts/imx6qdl.dtsi
index c003e62bf290..75bbaca34cbc 100644
--- a/arch/arm/boot/dts/imx6qdl.dtsi
+++ b/arch/arm/boot/dts/imx6qdl.dtsi
@@ -844,13 +844,23 @@
 			};
 
 			epit1: epit@20d0000 { /* EPIT1 */
+				compatible = "fsl,imx6q-epit";
 				reg = <0x020d0000 0x4000>;
 				interrupts = <0 56 IRQ_TYPE_LEVEL_HIGH>;
+				clocks = <&clks IMX6QDL_CLK_EPIT1>,
+					<&clks IMX6QDL_CLK_IPG_PER>;
+				clock-names = "ipg", "per";
+				status = "disabled";
 			};
 
 			epit2: epit@20d4000 { /* EPIT2 */
+				compatible = "fsl,imx6q-epit";
 				reg = <0x020d4000 0x4000>;
 				interrupts = <0 57 IRQ_TYPE_LEVEL_HIGH>;
+				clocks = <&clks IMX6QDL_CLK_EPIT2>,
+					<&clks IMX6QDL_CLK_IPG_PER>;
+				clock-names = "ipg", "per";
+				status = "disabled";
 			};
 
 			src: src@20d8000 {
-- 
2.17.0


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Re: [PATCH v3 4/5] clocksource: add driver for i.MX EPIT timer

[Fabio Estevam]

On Tue, May 29, 2018 at 2:04 PM, Clément Péron <peron.clem@gmail.com> wrote:

> +static int __init epit_timer_init(struct device_node *np)
> +{
> +       struct epit_timer *epittm;
> +       struct clk *clk_ipg;
> +       int ret;
> +
> +       epittm = kzalloc(sizeof(*epittm), GFP_KERNEL);
> +       if (!epittm)
> +               return -ENOMEM;
> +
> +       epittm->base = of_iomap(np, 0);
> +       if (!epittm->base) {
> +               ret = -ENXIO;
> +               goto out_kfree;
> +       }
> +
> +       epittm->irq = irq_of_parse_and_map(np, 0);
> +       if (!epittm->irq) {
> +               ret = -EINVAL;
> +               goto out_iounmap;
> +       }
> +
> +       clk_ipg = of_clk_get_by_name(np, "ipg");
> +       if (IS_ERR(clk_ipg)) {
> +               pr_err("i.MX EPIT: unable to get clk_ipg\n");
> +               ret = PTR_ERR(clk_ipg);
> +               goto out_iounmap;
> +       }
> +
> +       ret = clk_prepare_enable(clk_ipg);
> +       if (ret) {
> +               pr_err("i.MX EPIT: unable to prepare+enable clk_ipg\n");
> +               goto out_clk_ipg_disable;

This should be: goto out_iounmap;

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Re: [PATCH v3 4/5] clocksource: add driver for i.MX EPIT timer

[Vladimir Zapolskiy]

Hi Clément,

please find some more review comments.

On 05/29/2018 08:04 PM, Clément Péron wrote:
> From: Colin Didier <colin.didier@devialet.com>
> 
> Add driver for NXP's EPIT timer used in i.MX 6 family of SoC.
> 
> Signed-off-by: Colin Didier <colin.didier@devialet.com>
> Signed-off-by: Clément Peron <clement.peron@devialet.com>
> ---
>  drivers/clocksource/Kconfig          |  12 ++
>  drivers/clocksource/Makefile         |   1 +
>  drivers/clocksource/timer-imx-epit.c | 283 +++++++++++++++++++++++++++
>  3 files changed, 296 insertions(+)
>  create mode 100644 drivers/clocksource/timer-imx-epit.c
> 
> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> index 8e8a09755d10..920a0874f3a4 100644
> --- a/drivers/clocksource/Kconfig
> +++ b/drivers/clocksource/Kconfig
> @@ -576,6 +576,18 @@ config H8300_TPU
>  	  This enables the clocksource for the H8300 platform with the
>  	  H8S2678 cpu.
>  
> +config CLKSRC_IMX_EPIT
> +	bool "Clocksource using i.MX EPIT"
> +	depends on ARM && CLKDEV_LOOKUP && OF && (ARCH_MXC || COMPILE_TEST)

Here 'depends on ARM' can be removed, because ARCH_MXC implies it.

Also ARCH_MXC implies ARCH_MULTIPLATFORM, which implies USE_OF in turn,
so I would say that the following line is correct, sorry about a previous
comment asking to add an explicit OF dependency:

	depends on CLKDEV_LOOKUP && (ARCH_MXC || COMPILE_TEST)

However most of the clocksource drivers follow 'bool "..." if COMPILE_TEST'
pattern, and it might be preferable to maintainers.

> +	select TIMER_OF

The driver does not have this dependency.

> +	select CLKSRC_MMIO
> +	help
> +	  This enables EPIT support available on some i.MX platforms.
> +	  Normally you don't have a reason to do so as the EPIT has
> +	  the same features and uses the same clocks as the GPT.
> +	  Anyway, on some systems the GPT may be in use for other
> +	  purposes.
> +
>  config CLKSRC_IMX_GPT
>  	bool "Clocksource using i.MX GPT" if COMPILE_TEST
>  	depends on ARM && CLKDEV_LOOKUP
> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> index 00caf37e52f9..d9426f69ec69 100644
> --- a/drivers/clocksource/Makefile
> +++ b/drivers/clocksource/Makefile
> @@ -69,6 +69,7 @@ obj-$(CONFIG_INTEGRATOR_AP_TIMER)	+= timer-integrator-ap.o
>  obj-$(CONFIG_CLKSRC_VERSATILE)		+= versatile.o
>  obj-$(CONFIG_CLKSRC_MIPS_GIC)		+= mips-gic-timer.o
>  obj-$(CONFIG_CLKSRC_TANGO_XTAL)		+= tango_xtal.o
> +obj-$(CONFIG_CLKSRC_IMX_EPIT)		+= timer-imx-epit.o
>  obj-$(CONFIG_CLKSRC_IMX_GPT)		+= timer-imx-gpt.o
>  obj-$(CONFIG_CLKSRC_IMX_TPM)		+= timer-imx-tpm.o
>  obj-$(CONFIG_ASM9260_TIMER)		+= asm9260_timer.o
> diff --git a/drivers/clocksource/timer-imx-epit.c b/drivers/clocksource/timer-imx-epit.c
> new file mode 100644
> index 000000000000..87025d5f3a97
> --- /dev/null
> +++ b/drivers/clocksource/timer-imx-epit.c
> @@ -0,0 +1,283 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * i.MX EPIT Timer
> + *
> + * Copyright (C) 2010 Sascha Hauer <s.hauer@pengutronix.de>
> + * Copyright (C) 2018 Colin Didier <colin.didier@devialet.com>
> + * Copyright (C) 2018 Clément Péron <clement.peron@devialet.com>
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/clockchips.h>
> +#include <linux/err.h>

The include above can be dropped.

> +#include <linux/interrupt.h>
> +#include <linux/irq.h>

The include above can be dropped.

> +#include <linux/of_address.h>
> +#include <linux/of_irq.h>
> +#include <linux/of.h>

The include above can be dropped.

> +#include <linux/sched_clock.h>
> +#include <linux/slab.h>
> +
> +#define EPITCR				0x00
> +#define EPITSR				0x04
> +#define EPITLR				0x08
> +#define EPITCMPR			0x0c
> +#define EPITCNR				0x10
> +
> +#define EPITCR_EN			BIT(0)
> +#define EPITCR_ENMOD			BIT(1)
> +#define EPITCR_OCIEN			BIT(2)
> +#define EPITCR_RLD			BIT(3)
> +#define EPITCR_PRESC(x)			(((x) & 0xfff) << 4)
> +#define EPITCR_SWR			BIT(16)
> +#define EPITCR_IOVW			BIT(17)
> +#define EPITCR_DBGEN			BIT(18)
> +#define EPITCR_WAITEN			BIT(19)
> +#define EPITCR_RES			BIT(20)
> +#define EPITCR_STOPEN			BIT(21)
> +#define EPITCR_OM_DISCON		(0 << 22)
> +#define EPITCR_OM_TOGGLE		(1 << 22)
> +#define EPITCR_OM_CLEAR			(2 << 22)
> +#define EPITCR_OM_SET			(3 << 22)
> +#define EPITCR_CLKSRC_OFF		(0 << 24)
> +#define EPITCR_CLKSRC_PERIPHERAL	(1 << 24)
> +#define EPITCR_CLKSRC_REF_HIGH		(2 << 24)
> +#define EPITCR_CLKSRC_REF_LOW		(3 << 24)
> +
> +#define EPITSR_OCIF			BIT(0)
> +
> +struct epit_timer {
> +	void __iomem *base;
> +	int irq;
> +	struct clk *clk_per;
> +	struct clock_event_device ced;
> +	struct irqaction act;
> +};
> +
> +static void __iomem *sched_clock_reg;
> +
> +static inline struct epit_timer *to_epit_timer(struct clock_event_device *ced)
> +{
> +	return container_of(ced, struct epit_timer, ced);
> +}
> +
> +static inline void epit_irq_disable(struct epit_timer *epittm)
> +{
> +	u32 val;
> +
> +	val = readl_relaxed(epittm->base + EPITCR);
> +	writel_relaxed(val & ~EPITCR_OCIEN, epittm->base + EPITCR);
> +}
> +
> +static inline void epit_irq_enable(struct epit_timer *epittm)
> +{
> +	u32 val;
> +
> +	val = readl_relaxed(epittm->base + EPITCR);
> +	writel_relaxed(val | EPITCR_OCIEN, epittm->base + EPITCR);
> +}
> +
> +static void epit_irq_acknowledge(struct epit_timer *epittm)
> +{
> +	writel_relaxed(EPITSR_OCIF, epittm->base + EPITSR);
> +}
> +
> +static u64 notrace epit_read_sched_clock(void)
> +{
> +	return ~readl_relaxed(sched_clock_reg);
> +}
> +
> +static int __init epit_clocksource_init(struct epit_timer *epittm)
> +{
> +	unsigned int c = clk_get_rate(epittm->clk_per);
> +
> +	sched_clock_reg = epittm->base + EPITCNR;
> +	sched_clock_register(epit_read_sched_clock, 32, c);
> +
> +	return clocksource_mmio_init(epittm->base + EPITCNR, "epit", c, 200, 32,
> +			clocksource_mmio_readl_down);
> +}
> +

I would suggest to place epit_clocksource_init() function right before
epit_timer_init().

> +static int epit_set_next_event(unsigned long cycles,
> +			       struct clock_event_device *ced)
> +{
> +	struct epit_timer *epittm = to_epit_timer(ced);
> +	unsigned long tcmp;
> +
> +	tcmp = readl_relaxed(epittm->base + EPITCNR) - cycles;
> +	writel_relaxed(tcmp, epittm->base + EPITCMPR);
> +
> +	return 0;
> +}
> +
> +/* Left event sources disabled, no more interrupts appear */
> +static int epit_shutdown(struct clock_event_device *ced)
> +{
> +	struct epit_timer *epittm = to_epit_timer(ced);
> +	unsigned long flags;
> +
> +	/*
> +	 * The timer interrupt generation is disabled at least
> +	 * for enough time to call epit_set_next_event()
> +	 */
> +	local_irq_save(flags);
> +
> +	/* Disable interrupt in EPIT module */
> +	epit_irq_disable(epittm);
> +
> +	/* Clear pending interrupt */
> +	epit_irq_acknowledge(epittm);
> +
> +	local_irq_restore(flags);
> +
> +	return 0;
> +}
> +
> +static int epit_set_oneshot(struct clock_event_device *ced)
> +{
> +	struct epit_timer *epittm = to_epit_timer(ced);
> +	unsigned long flags;
> +
> +	/*
> +	 * The timer interrupt generation is disabled at least
> +	 * for enough time to call epit_set_next_event()
> +	 */
> +	local_irq_save(flags);
> +
> +	/* Disable interrupt in EPIT module */
> +	epit_irq_disable(epittm);
> +
> +	/* Clear pending interrupt, only while switching mode */
> +	if (!clockevent_state_oneshot(ced))
> +		epit_irq_acknowledge(epittm);
> +
> +	/*
> +	 * Do not put overhead of interrupt enable/disable into
> +	 * epit_set_next_event(), the core has about 4 minutes
> +	 * to call epit_set_next_event() or shutdown clock after
> +	 * mode switching
> +	 */
> +	epit_irq_enable(epittm);
> +	local_irq_restore(flags);
> +
> +	return 0;
> +}
> +
> +static irqreturn_t epit_timer_interrupt(int irq, void *dev_id)
> +{
> +	struct clock_event_device *ced = dev_id;
> +	struct epit_timer *epittm = to_epit_timer(ced);
> +
> +	epit_irq_acknowledge(epittm);
> +
> +	ced->event_handler(ced);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int __init epit_clockevent_init(struct epit_timer *epittm)
> +{
> +	struct clock_event_device *ced = &epittm->ced;
> +	struct irqaction *act = &epittm->act;
> +
> +	ced->name = "epit";
> +	ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_DYNIRQ;
> +	ced->set_state_shutdown = epit_shutdown;
> +	ced->tick_resume = epit_shutdown;
> +	ced->set_state_oneshot = epit_set_oneshot;
> +	ced->set_next_event = epit_set_next_event;
> +	ced->rating = 200;
> +	ced->cpumask = cpumask_of(0);
> +	ced->irq = epittm->irq;
> +	clockevents_config_and_register(ced, clk_get_rate(epittm->clk_per),
> +		0xff, 0xfffffffe);

Please indent the wrapped line.

> +
> +	act->name = "i.MX EPIT Timer Tick",
> +	act->flags = IRQF_TIMER | IRQF_IRQPOLL;
> +	act->handler = epit_timer_interrupt;
> +	act->dev_id = ced;
> +
> +	/* Make irqs happen */
> +	return setup_irq(epittm->irq, act);
> +}
> +
> +static int __init epit_timer_init(struct device_node *np)
> +{
> +	struct epit_timer *epittm;
> +	struct clk *clk_ipg;
> +	int ret;
> +
> +	epittm = kzalloc(sizeof(*epittm), GFP_KERNEL);
> +	if (!epittm)
> +		return -ENOMEM;
> +
> +	epittm->base = of_iomap(np, 0);
> +	if (!epittm->base) {
> +		ret = -ENXIO;
> +		goto out_kfree;
> +	}
> +
> +	epittm->irq = irq_of_parse_and_map(np, 0);
> +	if (!epittm->irq) {
> +		ret = -EINVAL;
> +		goto out_iounmap;
> +	}
> +
> +	clk_ipg = of_clk_get_by_name(np, "ipg");
> +	if (IS_ERR(clk_ipg)) {
> +		pr_err("i.MX EPIT: unable to get clk_ipg\n");
> +		ret = PTR_ERR(clk_ipg);
> +		goto out_iounmap;
> +	}
> +
> +	ret = clk_prepare_enable(clk_ipg);
> +	if (ret) {
> +		pr_err("i.MX EPIT: unable to prepare+enable clk_ipg\n");
> +		goto out_clk_ipg_disable;
> +	}
> +
> +	epittm->clk_per = of_clk_get_by_name(np, "per");
> +	if (IS_ERR(epittm->clk_per)) {
> +		pr_err("i.MX EPIT: unable to get clk_per\n");
> +		ret = PTR_ERR(epittm->clk_per);
> +		goto out_clk_ipg_disable;
> +	}
> +
> +	ret = clk_prepare_enable(epittm->clk_per);
> +	if (ret) {
> +		pr_err("i.MX EPIT: unable to prepare+enable clk_per\n");
> +		goto out_clk_ipg_disable;
> +	}
> +
> +	/* Initialise to a known state (all timers off, and timing reset) */
> +	writel_relaxed(0x0, epittm->base + EPITCR);
> +	writel_relaxed(0xffffffff, epittm->base + EPITLR);
> +	writel_relaxed(EPITCR_EN | EPITCR_CLKSRC_REF_HIGH | EPITCR_WAITEN,
> +		       epittm->base + EPITCR);
> +
> +	ret = epit_clocksource_init(epittm);
> +	if(ret) {

Add a space before left parenthesis.

> +		pr_err("i.MX EPIT: failed to init clocksource\n");
> +		goto out_clk_per_disable;
> +	}
> +
> +	ret = epit_clockevent_init(epittm);
> +	if(ret) {

Add a space before left parenthesis.

> +		pr_err("i.MX EPIT: failed to init clockevent\n");
> +		goto out_clk_per_disable;
> +	}
> +
> +	return 0;
> +
> +out_clk_per_disable:
> +	clk_disable_unprepare(epittm->clk_per);
> +out_clk_ipg_disable:
> +	clk_disable_unprepare(clk_ipg);
> +out_iounmap:
> +	iounmap(epittm->base);
> +out_kfree:
> +	kfree(epittm);
> +
> +	return ret;
> +}
> +TIMER_OF_DECLARE(mx6q_timer, "fsl,imx6q-epit", epit_timer_init);
> 

Here "fsl,imx31-epit" would be way better than "fsl,imx6q-epit", please
fix it in the documentation as well.

--
With best wishes,
Vladimir

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Re: [PATCH v3 3/5] Documentation: DT: add i.MX EPIT timer binding

[Vladimir Zapolskiy]

Hi Clément,

On 05/29/2018 08:04 PM, Clément Péron wrote:
> From: Clément Peron <clement.peron@devialet.com>
> 
> Add devicetree binding document for NXP's i.MX SoC specific
> EPIT timer driver.
> 
> Signed-off-by: Clément Peron <clement.peron@devialet.com>
> ---
>  .../devicetree/bindings/clock/imx6q,epit.txt  | 24 +++++++++++++++++++
>  1 file changed, 24 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/imx6q,epit.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/imx6q,epit.txt b/Documentation/devicetree/bindings/clock/imx6q,epit.txt
> new file mode 100644
> index 000000000000..a84a60c6ae35
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/imx6q,epit.txt

The file should be renamed to a more generic name like 'imx,epit.txt'
or 'imx31,epit.txt'.

Also note that the folder is incorrectly selected, it must be
Documentation/devicetree/bindings/timer/

> @@ -0,0 +1,24 @@
> +Binding for the i.MX6 EPIT timer

Let's change it to 'Binding for the i.MX EPIT timer'.

> +
> +This binding uses the common clock binding[1].
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +Required properties:
> +- compatible: should be "fsl,imx6q-epit"

Compatible should be "fsl,imx31-epit", i.MX31 SoC seems to be the first
one in the series, which has the timer module.

There should be added more compatibles specific to later SoC versions.

> +- reg: physical base address of the controller and length of memory mapped
> +  region.
> +- interrupts: Should contain EPIT controller interrupt
> +- clocks: list of clock specifiers, must contain an entry for each required
> +  entry in clock-names
> +- clock-names : should include entries "ipg", "per"
> +
> +Example:
> +	epit1: epit@20d0000 {
> +		compatible = "fsl,imx6q-epit";

For i.MX6Q example a list of compatibles should be updated like

	compatible = "fsl,imx6q-epit", "fsl,imx31-epit";

> +		reg = <0x020d0000 0x4000>;
> +		interrupts = <0 56 IRQ_TYPE_LEVEL_HIGH>;
> +		clocks = <&clks IMX6QDL_CLK_EPIT1>,
> +			<&clks IMX6QDL_CLK_IPG_PER>;
> +		clock-names = "ipg", "per";

It looks like "ipg" and "per" clocks are swapped, please double check it.

> +	};
> 

--
With best wishes,
Vladimir

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Re: [PATCH v3 3/5] Documentation: DT: add i.MX EPIT timer binding

[Vladimir Zapolskiy]

On 05/30/2018 10:27 AM, Vladimir Zapolskiy wrote:
> Hi Clément,
> 
> On 05/29/2018 08:04 PM, Clément Péron wrote:
>> From: Clément Peron <clement.peron@devialet.com>
>>
>> Add devicetree binding document for NXP's i.MX SoC specific
>> EPIT timer driver.
>>
>> Signed-off-by: Clément Peron <clement.peron@devialet.com>
>> ---
>>  .../devicetree/bindings/clock/imx6q,epit.txt  | 24 +++++++++++++++++++
>>  1 file changed, 24 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/clock/imx6q,epit.txt
>>
>> diff --git a/Documentation/devicetree/bindings/clock/imx6q,epit.txt b/Documentation/devicetree/bindings/clock/imx6q,epit.txt
>> new file mode 100644
>> index 000000000000..a84a60c6ae35
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/clock/imx6q,epit.txt
> 
> The file should be renamed to a more generic name like 'imx,epit.txt'
> or 'imx31,epit.txt'.
> 
> Also note that the folder is incorrectly selected, it must be
> Documentation/devicetree/bindings/timer/
> 

And linux-clk mailing list for publishing seems to be improper one,
instead please add Daniel Lezcano <daniel.lezcano@linaro.org> and
Thomas Gleixner <tglx@linutronix.de> to the list of addressees,
and the proper mailing list address is linux-kernel@vger.kernel.org

--
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Vladimir

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Re: [PATCH v3 4/5] clocksource: add driver for i.MX EPIT timer

[Clément PERON]

Hi Vladimir,

Le mer. 30 mai 2018 à 08:56, Vladimir Zapolskiy <
vladimir_zapolskiy@mentor.com> a écrit :

> Hi Clément,

> please find some more review comments.

> On 05/29/2018 08:04 PM, Clément Péron wrote:
> > From: Colin Didier <colin.didier@devialet.com>
> >
> > Add driver for NXP's EPIT timer used in i.MX 6 family of SoC.
> >
> > Signed-off-by: Colin Didier <colin.didier@devialet.com>
> > Signed-off-by: Clément Peron <clement.peron@devialet.com>
> > ---
> >  drivers/clocksource/Kconfig          |  12 ++
> >  drivers/clocksource/Makefile         |   1 +
> >  drivers/clocksource/timer-imx-epit.c | 283 +++++++++++++++++++++++++++
> >  3 files changed, 296 insertions(+)
> >  create mode 100644 drivers/clocksource/timer-imx-epit.c
> >
> > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
> > index 8e8a09755d10..920a0874f3a4 100644
> > --- a/drivers/clocksource/Kconfig
> > +++ b/drivers/clocksource/Kconfig
> > @@ -576,6 +576,18 @@ config H8300_TPU
> >         This enables the clocksource for the H8300 platform with the
> >         H8S2678 cpu.
> >
> > +config CLKSRC_IMX_EPIT
> > +     bool "Clocksource using i.MX EPIT"
> > +     depends on ARM && CLKDEV_LOOKUP && OF && (ARCH_MXC ||
COMPILE_TEST)

> Here 'depends on ARM' can be removed, because ARCH_MXC implies it.

> Also ARCH_MXC implies ARCH_MULTIPLATFORM, which implies USE_OF in turn,
> so I would say that the following line is correct, sorry about a previous
> comment asking to add an explicit OF dependency:

>          depends on CLKDEV_LOOKUP && (ARCH_MXC || COMPILE_TEST)

> However most of the clocksource drivers follow 'bool "..." if
COMPILE_TEST'
> pattern, and it might be preferable to maintainers.

Usually, the timer driver are selected in the arch Kconfig. But in this
case,
we want to keep the i.MX GPT except if the user explicitly select the i.MX
EPIT.
With the "if COMPILE_TEST" the user can't choose it.


> > +     select TIMER_OF

> The driver does not have this dependency.

> > +     select CLKSRC_MMIO
> > +     help
> > +       This enables EPIT support available on some i.MX platforms.
> > +       Normally you don't have a reason to do so as the EPIT has
> > +       the same features and uses the same clocks as the GPT.
> > +       Anyway, on some systems the GPT may be in use for other
> > +       purposes.
> > +
> >  config CLKSRC_IMX_GPT
> >       bool "Clocksource using i.MX GPT" if COMPILE_TEST
> >       depends on ARM && CLKDEV_LOOKUP
> > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
> > index 00caf37e52f9..d9426f69ec69 100644
> > --- a/drivers/clocksource/Makefile
> > +++ b/drivers/clocksource/Makefile
> > @@ -69,6 +69,7 @@ obj-$(CONFIG_INTEGRATOR_AP_TIMER)   +=
timer-integrator-ap.o
> >  obj-$(CONFIG_CLKSRC_VERSATILE)               += versatile.o
> >  obj-$(CONFIG_CLKSRC_MIPS_GIC)                += mips-gic-timer.o
> >  obj-$(CONFIG_CLKSRC_TANGO_XTAL)              += tango_xtal.o
> > +obj-$(CONFIG_CLKSRC_IMX_EPIT)                += timer-imx-epit.o
> >  obj-$(CONFIG_CLKSRC_IMX_GPT)         += timer-imx-gpt.o
> >  obj-$(CONFIG_CLKSRC_IMX_TPM)         += timer-imx-tpm.o
> >  obj-$(CONFIG_ASM9260_TIMER)          += asm9260_timer.o
> > diff --git a/drivers/clocksource/timer-imx-epit.c
b/drivers/clocksource/timer-imx-epit.c
> > new file mode 100644
> > index 000000000000..87025d5f3a97
> > --- /dev/null
> > +++ b/drivers/clocksource/timer-imx-epit.c
> > @@ -0,0 +1,283 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * i.MX EPIT Timer
> > + *
> > + * Copyright (C) 2010 Sascha Hauer <s.hauer@pengutronix.de>
> > + * Copyright (C) 2018 Colin Didier <colin.didier@devialet.com>
> > + * Copyright (C) 2018 Clément Péron <clement.peron@devialet.com>
> > + */
> > +
> > +#include <linux/clk.h>
> > +#include <linux/clockchips.h>
> > +#include <linux/err.h>

> The include above can be dropped.

> > +#include <linux/interrupt.h>
> > +#include <linux/irq.h>

> The include above can be dropped.

> > +#include <linux/of_address.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/of.h>

> The include above can be dropped.

> > +#include <linux/sched_clock.h>
> > +#include <linux/slab.h>
> > +
> > +#define EPITCR                               0x00
> > +#define EPITSR                               0x04
> > +#define EPITLR                               0x08
> > +#define EPITCMPR                     0x0c
> > +#define EPITCNR                              0x10
> > +
> > +#define EPITCR_EN                    BIT(0)
> > +#define EPITCR_ENMOD                 BIT(1)
> > +#define EPITCR_OCIEN                 BIT(2)
> > +#define EPITCR_RLD                   BIT(3)
> > +#define EPITCR_PRESC(x)                      (((x) & 0xfff) << 4)
> > +#define EPITCR_SWR                   BIT(16)
> > +#define EPITCR_IOVW                  BIT(17)
> > +#define EPITCR_DBGEN                 BIT(18)
> > +#define EPITCR_WAITEN                        BIT(19)
> > +#define EPITCR_RES                   BIT(20)
> > +#define EPITCR_STOPEN                        BIT(21)
> > +#define EPITCR_OM_DISCON             (0 << 22)
> > +#define EPITCR_OM_TOGGLE             (1 << 22)
> > +#define EPITCR_OM_CLEAR                      (2 << 22)
> > +#define EPITCR_OM_SET                        (3 << 22)
> > +#define EPITCR_CLKSRC_OFF            (0 << 24)
> > +#define EPITCR_CLKSRC_PERIPHERAL     (1 << 24)
> > +#define EPITCR_CLKSRC_REF_HIGH               (2 << 24)
> > +#define EPITCR_CLKSRC_REF_LOW                (3 << 24)
> > +
> > +#define EPITSR_OCIF                  BIT(0)
> > +
> > +struct epit_timer {
> > +     void __iomem *base;
> > +     int irq;
> > +     struct clk *clk_per;
> > +     struct clock_event_device ced;
> > +     struct irqaction act;
> > +};
> > +
> > +static void __iomem *sched_clock_reg;
> > +
> > +static inline struct epit_timer *to_epit_timer(struct
clock_event_device *ced)
> > +{
> > +     return container_of(ced, struct epit_timer, ced);
> > +}
> > +
> > +static inline void epit_irq_disable(struct epit_timer *epittm)
> > +{
> > +     u32 val;
> > +
> > +     val = readl_relaxed(epittm->base + EPITCR);
> > +     writel_relaxed(val & ~EPITCR_OCIEN, epittm->base + EPITCR);
> > +}
> > +
> > +static inline void epit_irq_enable(struct epit_timer *epittm)
> > +{
> > +     u32 val;
> > +
> > +     val = readl_relaxed(epittm->base + EPITCR);
> > +     writel_relaxed(val | EPITCR_OCIEN, epittm->base + EPITCR);
> > +}
> > +
> > +static void epit_irq_acknowledge(struct epit_timer *epittm)
> > +{
> > +     writel_relaxed(EPITSR_OCIF, epittm->base + EPITSR);
> > +}
> > +
> > +static u64 notrace epit_read_sched_clock(void)
> > +{
> > +     return ~readl_relaxed(sched_clock_reg);
> > +}
> > +
> > +static int __init epit_clocksource_init(struct epit_timer *epittm)
> > +{
> > +     unsigned int c = clk_get_rate(epittm->clk_per);
> > +
> > +     sched_clock_reg = epittm->base + EPITCNR;
> > +     sched_clock_register(epit_read_sched_clock, 32, c);
> > +
> > +     return clocksource_mmio_init(epittm->base + EPITCNR, "epit", c,
200, 32,
> > +                     clocksource_mmio_readl_down);
> > +}
> > +

> I would suggest to place epit_clocksource_init() function right before
> epit_timer_init().

> > +static int epit_set_next_event(unsigned long cycles,
> > +                            struct clock_event_device *ced)
> > +{
> > +     struct epit_timer *epittm = to_epit_timer(ced);
> > +     unsigned long tcmp;
> > +
> > +     tcmp = readl_relaxed(epittm->base + EPITCNR) - cycles;
> > +     writel_relaxed(tcmp, epittm->base + EPITCMPR);
> > +
> > +     return 0;
> > +}
> > +
> > +/* Left event sources disabled, no more interrupts appear */
> > +static int epit_shutdown(struct clock_event_device *ced)
> > +{
> > +     struct epit_timer *epittm = to_epit_timer(ced);
> > +     unsigned long flags;
> > +
> > +     /*
> > +      * The timer interrupt generation is disabled at least
> > +      * for enough time to call epit_set_next_event()
> > +      */
> > +     local_irq_save(flags);
> > +
> > +     /* Disable interrupt in EPIT module */
> > +     epit_irq_disable(epittm);
> > +
> > +     /* Clear pending interrupt */
> > +     epit_irq_acknowledge(epittm);
> > +
> > +     local_irq_restore(flags);
> > +
> > +     return 0;
> > +}
> > +
> > +static int epit_set_oneshot(struct clock_event_device *ced)
> > +{
> > +     struct epit_timer *epittm = to_epit_timer(ced);
> > +     unsigned long flags;
> > +
> > +     /*
> > +      * The timer interrupt generation is disabled at least
> > +      * for enough time to call epit_set_next_event()
> > +      */
> > +     local_irq_save(flags);
> > +
> > +     /* Disable interrupt in EPIT module */
> > +     epit_irq_disable(epittm);
> > +
> > +     /* Clear pending interrupt, only while switching mode */
> > +     if (!clockevent_state_oneshot(ced))
> > +             epit_irq_acknowledge(epittm);
> > +
> > +     /*
> > +      * Do not put overhead of interrupt enable/disable into
> > +      * epit_set_next_event(), the core has about 4 minutes
> > +      * to call epit_set_next_event() or shutdown clock after
> > +      * mode switching
> > +      */
> > +     epit_irq_enable(epittm);
> > +     local_irq_restore(flags);
> > +
> > +     return 0;
> > +}
> > +
> > +static irqreturn_t epit_timer_interrupt(int irq, void *dev_id)
> > +{
> > +     struct clock_event_device *ced = dev_id;
> > +     struct epit_timer *epittm = to_epit_timer(ced);
> > +
> > +     epit_irq_acknowledge(epittm);
> > +
> > +     ced->event_handler(ced);
> > +
> > +     return IRQ_HANDLED;
> > +}
> > +
> > +static int __init epit_clockevent_init(struct epit_timer *epittm)
> > +{
> > +     struct clock_event_device *ced = &epittm->ced;
> > +     struct irqaction *act = &epittm->act;
> > +
> > +     ced->name = "epit";
> > +     ced->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_DYNIRQ;
> > +     ced->set_state_shutdown = epit_shutdown;
> > +     ced->tick_resume = epit_shutdown;
> > +     ced->set_state_oneshot = epit_set_oneshot;
> > +     ced->set_next_event = epit_set_next_event;
> > +     ced->rating = 200;
> > +     ced->cpumask = cpumask_of(0);
> > +     ced->irq = epittm->irq;
> > +     clockevents_config_and_register(ced,
clk_get_rate(epittm->clk_per),
> > +             0xff, 0xfffffffe);

> Please indent the wrapped line.

> > +
> > +     act->name = "i.MX EPIT Timer Tick",
> > +     act->flags = IRQF_TIMER | IRQF_IRQPOLL;
> > +     act->handler = epit_timer_interrupt;
> > +     act->dev_id = ced;
> > +
> > +     /* Make irqs happen */
> > +     return setup_irq(epittm->irq, act);
> > +}
> > +
> > +static int __init epit_timer_init(struct device_node *np)
> > +{
> > +     struct epit_timer *epittm;
> > +     struct clk *clk_ipg;
> > +     int ret;
> > +
> > +     epittm = kzalloc(sizeof(*epittm), GFP_KERNEL);
> > +     if (!epittm)
> > +             return -ENOMEM;
> > +
> > +     epittm->base = of_iomap(np, 0);
> > +     if (!epittm->base) {
> > +             ret = -ENXIO;
> > +             goto out_kfree;
> > +     }
> > +
> > +     epittm->irq = irq_of_parse_and_map(np, 0);
> > +     if (!epittm->irq) {
> > +             ret = -EINVAL;
> > +             goto out_iounmap;
> > +     }
> > +
> > +     clk_ipg = of_clk_get_by_name(np, "ipg");
> > +     if (IS_ERR(clk_ipg)) {
> > +             pr_err("i.MX EPIT: unable to get clk_ipg\n");
> > +             ret = PTR_ERR(clk_ipg);
> > +             goto out_iounmap;
> > +     }
> > +
> > +     ret = clk_prepare_enable(clk_ipg);
> > +     if (ret) {
> > +             pr_err("i.MX EPIT: unable to prepare+enable clk_ipg\n");
> > +             goto out_clk_ipg_disable;
> > +     }
> > +
> > +     epittm->clk_per = of_clk_get_by_name(np, "per");
> > +     if (IS_ERR(epittm->clk_per)) {
> > +             pr_err("i.MX EPIT: unable to get clk_per\n");
> > +             ret = PTR_ERR(epittm->clk_per);
> > +             goto out_clk_ipg_disable;
> > +     }
> > +
> > +     ret = clk_prepare_enable(epittm->clk_per);
> > +     if (ret) {
> > +             pr_err("i.MX EPIT: unable to prepare+enable clk_per\n");
> > +             goto out_clk_ipg_disable;
> > +     }
> > +
> > +     /* Initialise to a known state (all timers off, and timing reset)
*/
> > +     writel_relaxed(0x0, epittm->base + EPITCR);
> > +     writel_relaxed(0xffffffff, epittm->base + EPITLR);
> > +     writel_relaxed(EPITCR_EN | EPITCR_CLKSRC_REF_HIGH | EPITCR_WAITEN,
> > +                    epittm->base + EPITCR);
> > +
> > +     ret = epit_clocksource_init(epittm);
> > +     if(ret) {

> Add a space before left parenthesis.

> > +             pr_err("i.MX EPIT: failed to init clocksource\n");
> > +             goto out_clk_per_disable;
> > +     }
> > +
> > +     ret = epit_clockevent_init(epittm);
> > +     if(ret) {

> Add a space before left parenthesis.

> > +             pr_err("i.MX EPIT: failed to init clockevent\n");
> > +             goto out_clk_per_disable;
> > +     }
> > +
> > +     return 0;
> > +
> > +out_clk_per_disable:
> > +     clk_disable_unprepare(epittm->clk_per);
> > +out_clk_ipg_disable:
> > +     clk_disable_unprepare(clk_ipg);
> > +out_iounmap:
> > +     iounmap(epittm->base);
> > +out_kfree:
> > +     kfree(epittm);
> > +
> > +     return ret;
> > +}
> > +TIMER_OF_DECLARE(mx6q_timer, "fsl,imx6q-epit", epit_timer_init);
> >

> Here "fsl,imx31-epit" would be way better than "fsl,imx6q-epit", please
> fix it in the documentation as well.

> --
> With best wishes,
> Vladimir


Thanks for your review,
Clement

-- 
https://www.devialet.com/buy-phantom <https://www.devialet.com/buy-phantom>



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Re: [PATCH v3 2/5] clk: imx6: add EPIT clock support

[Stephen Boyd]

Quoting Clément Péron (2018-05-29 10:04:33)
> From: Colin Didier <colin.didier@devialet.com>
> 
> Add EPIT clock support to the i.MX6Q clocking infrastructure.
> 
> Signed-off-by: Colin Didier <colin.didier@devialet.com>
> Signed-off-by: Clément Peron <clement.peron@devialet.com>
> Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
> ---

Applied to clk-next


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