diff mbox

[v2,02/10] clockevents/drivers: add MPS2 Timer driver

Message ID 1454413199-26573-3-git-send-email-vladimir.murzin@arm.com
State New, archived
Headers show

Commit Message

Vladimir Murzin Feb. 2, 2016, 11:39 a.m. UTC
MPS2 platform has simple 32 bits general purpose countdown timers.

The driver uses the first detected timer as a clocksource and the rest
of the timers as a clockevent

Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
---
 drivers/clocksource/Kconfig      |    6 +
 drivers/clocksource/Makefile     |    1 +
 drivers/clocksource/mps2-timer.c |  276 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 283 insertions(+)
 create mode 100644 drivers/clocksource/mps2-timer.c

Comments

Thomas Gleixner Feb. 2, 2016, 1:04 p.m. UTC | #1
On Tue, 2 Feb 2016, Vladimir Murzin wrote:
> +static int __init mps2_clockevent_init(struct device_node *np)
> +{
> +	void __iomem *base;
> +	struct clk *clk;
> +	struct clockevent_mps2 *ce;
> +	u32 rate;
> +	int irq, ret;
> +	const char *name = "mps2-clkevt";
> +
> +	ret = of_property_read_u32(np, "clock-frequency", &rate);
> +	if (ret) {
> +		clk = of_clk_get(np, 0);
> +		if (IS_ERR(clk)) {
> +			ret = PTR_ERR(clk);
> +			pr_err("failed to get clock for clockevent: %d\n", ret);
> +			goto err_clk_get;
> +		}
> +
> +		ret = clk_prepare_enable(clk);
> +		if (ret) {
> +			pr_err("failed to enable clock for clockevent: %d\n", ret);
> +			clk_put(clk);
> +			goto err_clk_enable;
> +		}
> +
> +		rate = clk_get_rate(clk);
> +	}

So in case that "clock-frequency" is available in DT, what enables and
configures the clock?

> +err_ia_alloc:
> +	kfree(ce);
> +err_ce_alloc:
> +err_get_irq:
> +	iounmap(base);
> +err_iomap:
> +	clk_disable_unprepare(clk);

clk is not initialized when "clock-frequency" is available in DT. The compiler
should have told you ....

> +err_clk_enable:
> +	clk_put(clk);

Put without get ....

> +static int __init mps2_clocksource_init(struct device_node *np)
> +{
> +	void __iomem *base;
> +	struct clk *clk;
> +	u32 rate;
> +	int ret;
> +	const char *name = "mps2-clksrc";
> +
> +	ret = of_property_read_u32(np, "clock-frequency", &rate);
> +	if (ret) {
> +		clk = of_clk_get(np, 0);
> +		if (IS_ERR(clk)) {
> +			ret = PTR_ERR(clk);
> +			pr_err("failed to get clock for clocksource: %d\n", ret);
> +			goto err_clk_get;
> +		}
> +
> +		ret = clk_prepare_enable(clk);
> +		if (ret) {
> +			pr_err("failed to enable clock for clocksource: %d\n", ret);
> +			clk_put(clk);
> +			goto err_clk_enable;
> +		}
> +
> +		rate = clk_get_rate(clk);
> +	}

Same problem as above.

> +err_clocksource_init:
> +	iounmap(base);
> +err_iomap:
> +	clk_disable_unprepare(clk);

Ditto.

> +err_clk_enable:
> +	clk_put(clk);

Ditto.

> +err_clk_get:
> +	return ret;
> +}
> +
> +static void __init mps2_timer_init(struct device_node *np)
> +{
> +	static int has_clocksource, has_clockevent;
> +	int ret;
> +
> +	if (!has_clocksource) {
> +		ret = mps2_clocksource_init(np);
> +		if (!ret) {
> +			has_clocksource = 1;
> +			return;
> +		}
> +	}
> +
> +	if (!has_clockevent) {
> +		ret = mps2_clockevent_init(np);
> +		if (!ret) {
> +			has_clockevent = 1;
> +			return;
> +		}
> +	}

You take randomly the first timer as clocksource and the second one as
clockevent. If clocksource init fails, you try to install it as clockevent.

Sorry, but I really cannot follow the logic here.

Thanks,

	tglx
Vladimir Murzin Feb. 2, 2016, 2:06 p.m. UTC | #2
On 02/02/16 13:04, Thomas Gleixner wrote:
> On Tue, 2 Feb 2016, Vladimir Murzin wrote:
>> +static int __init mps2_clockevent_init(struct device_node *np)
>> +{
>> +	void __iomem *base;
>> +	struct clk *clk;
>> +	struct clockevent_mps2 *ce;
>> +	u32 rate;
>> +	int irq, ret;
>> +	const char *name = "mps2-clkevt";
>> +
>> +	ret = of_property_read_u32(np, "clock-frequency", &rate);
>> +	if (ret) {
>> +		clk = of_clk_get(np, 0);
>> +		if (IS_ERR(clk)) {
>> +			ret = PTR_ERR(clk);
>> +			pr_err("failed to get clock for clockevent: %d\n", ret);
>> +			goto err_clk_get;
>> +		}
>> +
>> +		ret = clk_prepare_enable(clk);
>> +		if (ret) {
>> +			pr_err("failed to enable clock for clockevent: %d\n", ret);
>> +			clk_put(clk);
>> +			goto err_clk_enable;
>> +		}
>> +
>> +		rate = clk_get_rate(clk);
>> +	}
> 
> So in case that "clock-frequency" is available in DT, what enables and
> configures the clock?

They are fixed-clock, so I ended up this *cough* mess *cough* shortcut.
I'd be glad if you share your thoughts what is preferred way to cope
with it (is it worth to do at all?)

> 
>> +err_ia_alloc:
>> +	kfree(ce);
>> +err_ce_alloc:
>> +err_get_irq:
>> +	iounmap(base);
>> +err_iomap:
>> +	clk_disable_unprepare(clk);
> 
> clk is not initialized when "clock-frequency" is available in DT. The compiler
> should have told you ....

Shame on me, I've completely messed it up :( Thanks for pointing at it,
I'll fix this an other places you pointed at...

> 
>> +err_clk_enable:
>> +	clk_put(clk);
> 
> Put without get ....

or double clk_put() if clk_prepare_enable() failed... shame, shame, shame

> 
>> +static int __init mps2_clocksource_init(struct device_node *np)
>> +{
>> +	void __iomem *base;
>> +	struct clk *clk;
>> +	u32 rate;
>> +	int ret;
>> +	const char *name = "mps2-clksrc";
>> +
>> +	ret = of_property_read_u32(np, "clock-frequency", &rate);
>> +	if (ret) {
>> +		clk = of_clk_get(np, 0);
>> +		if (IS_ERR(clk)) {
>> +			ret = PTR_ERR(clk);
>> +			pr_err("failed to get clock for clocksource: %d\n", ret);
>> +			goto err_clk_get;
>> +		}
>> +
>> +		ret = clk_prepare_enable(clk);
>> +		if (ret) {
>> +			pr_err("failed to enable clock for clocksource: %d\n", ret);
>> +			clk_put(clk);
>> +			goto err_clk_enable;
>> +		}
>> +
>> +		rate = clk_get_rate(clk);
>> +	}
> 
> Same problem as above.
> 
>> +err_clocksource_init:
>> +	iounmap(base);
>> +err_iomap:
>> +	clk_disable_unprepare(clk);
> 
> Ditto.
> 
>> +err_clk_enable:
>> +	clk_put(clk);
> 
> Ditto.
> 
>> +err_clk_get:
>> +	return ret;
>> +}
>> +
>> +static void __init mps2_timer_init(struct device_node *np)
>> +{
>> +	static int has_clocksource, has_clockevent;
>> +	int ret;
>> +
>> +	if (!has_clocksource) {
>> +		ret = mps2_clocksource_init(np);
>> +		if (!ret) {
>> +			has_clocksource = 1;
>> +			return;
>> +		}
>> +	}
>> +
>> +	if (!has_clockevent) {
>> +		ret = mps2_clockevent_init(np);
>> +		if (!ret) {
>> +			has_clockevent = 1;
>> +			return;
>> +		}
>> +	}
> 
> You take randomly the first timer as clocksource and the second one as
> clockevent. If clocksource init fails, you try to install it as clockevent.
> 
> Sorry, but I really cannot follow the logic here.
> 

It has been done as a response on Daniel's comment [1]. I'm quite happy
to get known what init sequence is expected here.

[1]
http://lists.infradead.org/pipermail/linux-arm-kernel/2015-November/388223.html

Thanks for your time, Thomas!

Vladimir

> Thanks,
> 
> 	tglx
> 
> 
>
diff mbox

Patch

diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
index 33db740..7ce3892 100644
--- a/drivers/clocksource/Kconfig
+++ b/drivers/clocksource/Kconfig
@@ -185,6 +185,12 @@  config CLKSRC_STM32
 	depends on OF && ARM && (ARCH_STM32 || COMPILE_TEST)
 	select CLKSRC_MMIO
 
+config CLKSRC_MPS2
+	bool "Clocksource for MPS2 SoCs" if COMPILE_TEST
+	depends on GENERIC_SCHED_CLOCK
+	select CLKSRC_MMIO
+	select CLKSRC_OF
+
 config ARM_ARCH_TIMER
 	bool
 	select CLKSRC_OF if OF
diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
index dc2b899..b0a3c96 100644
--- a/drivers/clocksource/Makefile
+++ b/drivers/clocksource/Makefile
@@ -39,6 +39,7 @@  obj-$(CONFIG_CLKSRC_EFM32)	+= time-efm32.o
 obj-$(CONFIG_CLKSRC_STM32)	+= timer-stm32.o
 obj-$(CONFIG_CLKSRC_EXYNOS_MCT)	+= exynos_mct.o
 obj-$(CONFIG_CLKSRC_LPC32XX)	+= time-lpc32xx.o
+obj-$(CONFIG_CLKSRC_MPS2)	+= mps2-timer.o
 obj-$(CONFIG_CLKSRC_SAMSUNG_PWM)	+= samsung_pwm_timer.o
 obj-$(CONFIG_FSL_FTM_TIMER)	+= fsl_ftm_timer.o
 obj-$(CONFIG_VF_PIT_TIMER)	+= vf_pit_timer.o
diff --git a/drivers/clocksource/mps2-timer.c b/drivers/clocksource/mps2-timer.c
new file mode 100644
index 0000000..0f529e9f
--- /dev/null
+++ b/drivers/clocksource/mps2-timer.c
@@ -0,0 +1,276 @@ 
+/*
+ * Copyright (C) 2015 ARM Limited
+ *
+ * Author: Vladimir Murzin <vladimir.murzin@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt
+
+#include <linux/clk.h>
+#include <linux/clockchips.h>
+#include <linux/clocksource.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/of_address.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+
+#define TIMER_CTRL		0x0
+#define TIMER_CTRL_ENABLE	BIT(0)
+#define TIMER_CTRL_IE		BIT(3)
+
+#define TIMER_VALUE		0x4
+#define TIMER_RELOAD		0x8
+#define TIMER_INT		0xc
+
+struct clockevent_mps2 {
+	void __iomem *reg;
+	u32 clock_count_per_tick;
+	struct clock_event_device clkevt;
+};
+
+static void __iomem *sched_clock_base;
+
+static u64 notrace mps2_sched_read(void)
+{
+        return ~readl_relaxed(sched_clock_base + TIMER_VALUE);
+}
+
+static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c)
+{
+	return container_of(c, struct clockevent_mps2, clkevt);
+}
+
+static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset)
+{
+	writel_relaxed(val, to_mps2_clkevt(c)->reg + offset);
+}
+
+static int mps2_timer_shutdown(struct clock_event_device *ce)
+{
+	clockevent_mps2_writel(0, ce, TIMER_RELOAD);
+	clockevent_mps2_writel(0, ce, TIMER_CTRL);
+
+	return 0;
+}
+
+static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce)
+{
+	clockevent_mps2_writel(next, ce, TIMER_VALUE);
+	clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
+
+	return 0;
+}
+
+static int mps2_timer_set_periodic(struct clock_event_device *ce)
+{
+	u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick;
+
+	clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD);
+	clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE);
+	clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
+
+	return 0;
+}
+
+static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id)
+{
+	struct clockevent_mps2 *ce = dev_id;
+	u32 status = readl_relaxed(ce->reg + TIMER_INT);
+
+	if (!status) {
+		pr_warn("spurious interrupt\n");
+		return IRQ_NONE;
+	}
+
+	writel_relaxed(1, ce->reg + TIMER_INT);
+
+	ce->clkevt.event_handler(&ce->clkevt);
+
+	return IRQ_HANDLED;
+}
+
+static int __init mps2_clockevent_init(struct device_node *np)
+{
+	void __iomem *base;
+	struct clk *clk;
+	struct clockevent_mps2 *ce;
+	u32 rate;
+	int irq, ret;
+	const char *name = "mps2-clkevt";
+
+	ret = of_property_read_u32(np, "clock-frequency", &rate);
+	if (ret) {
+		clk = of_clk_get(np, 0);
+		if (IS_ERR(clk)) {
+			ret = PTR_ERR(clk);
+			pr_err("failed to get clock for clockevent: %d\n", ret);
+			goto err_clk_get;
+		}
+
+		ret = clk_prepare_enable(clk);
+		if (ret) {
+			pr_err("failed to enable clock for clockevent: %d\n", ret);
+			clk_put(clk);
+			goto err_clk_enable;
+		}
+
+		rate = clk_get_rate(clk);
+	}
+
+	base = of_iomap(np, 0);
+	if (!base) {
+		ret = -EADDRNOTAVAIL;
+		pr_err("failed to map register for clockevent: %d\n", ret);
+		goto err_iomap;
+	}
+
+	irq = irq_of_parse_and_map(np, 0);
+	if (!irq) {
+		ret = -ENOENT;
+		pr_err("failed to get irq for clockevent: %d\n", ret);
+		goto err_get_irq;
+	}
+
+	ce = kzalloc(sizeof(struct clockevent_mps2), GFP_KERNEL);
+	if (!ce) {
+		ret = -ENOMEM;
+		goto err_ce_alloc;
+	}
+
+	ce->reg = base;
+	ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ);
+	ce->clkevt.irq = irq;
+	ce->clkevt.name = name;
+	ce->clkevt.rating = 200;
+	ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
+	ce->clkevt.cpumask = cpu_possible_mask;
+	ce->clkevt.set_state_shutdown	= mps2_timer_shutdown,
+	ce->clkevt.set_state_periodic	= mps2_timer_set_periodic,
+	ce->clkevt.set_state_oneshot	= mps2_timer_shutdown,
+	ce->clkevt.set_next_event	= mps2_timer_set_next_event;
+
+	/* Ensure timer is disabled */
+	writel_relaxed(0, base + TIMER_CTRL);
+
+	ret = request_irq(irq, mps2_timer_interrupt, IRQF_TIMER, name, ce);
+	if (ret) {
+		pr_err("failed to request irq: %d\n", ret);
+		goto err_ia_alloc;
+	}
+
+	clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff);
+
+	return 0;
+
+err_ia_alloc:
+	kfree(ce);
+err_ce_alloc:
+err_get_irq:
+	iounmap(base);
+err_iomap:
+	clk_disable_unprepare(clk);
+err_clk_enable:
+	clk_put(clk);
+err_clk_get:
+	return ret;
+}
+
+static int __init mps2_clocksource_init(struct device_node *np)
+{
+	void __iomem *base;
+	struct clk *clk;
+	u32 rate;
+	int ret;
+	const char *name = "mps2-clksrc";
+
+	ret = of_property_read_u32(np, "clock-frequency", &rate);
+	if (ret) {
+		clk = of_clk_get(np, 0);
+		if (IS_ERR(clk)) {
+			ret = PTR_ERR(clk);
+			pr_err("failed to get clock for clocksource: %d\n", ret);
+			goto err_clk_get;
+		}
+
+		ret = clk_prepare_enable(clk);
+		if (ret) {
+			pr_err("failed to enable clock for clocksource: %d\n", ret);
+			clk_put(clk);
+			goto err_clk_enable;
+		}
+
+		rate = clk_get_rate(clk);
+	}
+
+	base = of_iomap(np, 0);
+	if (!base) {
+		ret = -EADDRNOTAVAIL;
+		pr_err("failed to map register for clocksource: %d\n", ret);
+		goto err_iomap;
+	}
+
+	/* Ensure timer is disabled */
+	writel_relaxed(0, base + TIMER_CTRL);
+
+	/* ... and set it up as free-running clocksource */
+	writel_relaxed(0xffffffff, base + TIMER_VALUE);
+	writel_relaxed(0xffffffff, base + TIMER_RELOAD);
+
+	writel_relaxed(TIMER_CTRL_ENABLE, base + TIMER_CTRL);
+
+	ret = clocksource_mmio_init(base + TIMER_VALUE, name,
+				    rate, 200, 32,
+				    clocksource_mmio_readl_down);
+	if (ret) {
+		pr_err("failed to init clocksource: %d\n", ret);
+		goto err_clocksource_init;
+	}
+
+	sched_clock_base = base;
+	sched_clock_register(mps2_sched_read, 32, rate);
+
+	return 0;
+
+err_clocksource_init:
+	iounmap(base);
+err_iomap:
+	clk_disable_unprepare(clk);
+err_clk_enable:
+	clk_put(clk);
+err_clk_get:
+	return ret;
+}
+
+static void __init mps2_timer_init(struct device_node *np)
+{
+	static int has_clocksource, has_clockevent;
+	int ret;
+
+	if (!has_clocksource) {
+		ret = mps2_clocksource_init(np);
+		if (!ret) {
+			has_clocksource = 1;
+			return;
+		}
+	}
+
+	if (!has_clockevent) {
+		ret = mps2_clockevent_init(np);
+		if (!ret) {
+			has_clockevent = 1;
+			return;
+		}
+	}
+}
+
+CLOCKSOURCE_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);