On Sat, Feb 25, 2017 at 12:25:32AM +0100, Andreas F?rber wrote:

Am 24.02.2017 um 23:29 schrieb Daniel Lezcano:

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On Fri, Feb 24, 2017 at 04:40:42AM +0100, Andreas F?rber wrote:

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Implement clocksource and clockevents for Actions Semi S500.

Based on LeMaker linux-actions tree.

Signed-off-by: Andreas F?rber <afaerber@suse.de>

As this is a new driver, please give some technical information about the
driver itself and a pointer to documentation if it is publicly available.

What technical information would that be? Which of the timers we use as
clock source vs. clock events?

Have a look at commit 07862c1 and e4a6b37 as reference.
 

The only public documentation beyond the source tree mentioned is here:

http://www.lemaker.org/product-guitar-download-29.html (section 3.4)

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+#define OWL_Tx_CTL_INTEN	(1 << 1)
+#define OWL_Tx_CTL_EN		(1 << 2)

s/(1 << 1)/BIT(1)/
s/(1 << 2)/BIT(2)/

OK

[ ... ]

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+static struct clock_event_device owl_clockevent = {
+	.name			= "owl_tick",
+	.rating			= 200,
+	.features		= CLOCK_EVT_FEAT_ONESHOT,

Did you consider adding CLOCK_EVT_FEAT_DYNIRQ ?

No, it was not present downstream. Got a good example?

https://lwn.net/Articles/541000/

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+	.set_state_shutdown	= owl_timer_set_state_shutdown,
+	.set_state_oneshot	= owl_timer_set_state_oneshot,
+	.tick_resume		= owl_timer_tick_resume,
+	.set_next_event		= owl_timer_set_next_event,
+};
+
+static irqreturn_t owl_timer_interrupt(int irq, void *dev_id)
+{
+	struct clock_event_device *evt = (struct clock_event_device *)dev_id;
+
+	evt->event_handler(evt);
+
+	return IRQ_HANDLED;
+}
+
+static struct irqaction owl_timer_irq = {
+	.name = "owl-timer",
+	.flags = IRQF_TIMER,
+	.handler = owl_timer_interrupt,
+	.dev_id = &owl_clockevent,
+};
+
+static int __init owl_timer_init(struct device_node *node)
+{
+	const unsigned long rate = 24000000;

Use DT, either use clock-frequency or a clock ref.

Are clk drivers really available at this point? clock-frequency sounds
more promising.

Yes they are. Have a look at the other drivers.
 

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+	int irq1, ret;
+
+	owl_timer_base = of_io_request_and_map(node, 0, "owl-timer");
+	if (IS_ERR(owl_timer_base)) {
+		pr_err("Can't map timer registers");
+		return -ENXIO;

Why not PTR_ERR(owl_timer_base) ?

Only one in-tree driver (sun5i) matches such an expression. Will change.

[ ... ]

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Please factor out these calls into a function.

Do you have something in particular in mind? Maybe ..._reset() for the
first three?

Yes.

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+
+	sched_clock_register(owl_timer_sched_read, 32, rate);
+	clocksource_mmio_init(owl_timer_base + OWL_T0_VAL, node->name,
+			      rate, 200, 32, clocksource_mmio_readl_up);
+
+	writel(0, owl_timer_base + OWL_T1_CTL);
+	writel(0, owl_timer_base + OWL_T1_VAL);
+	writel(0, owl_timer_base + OWL_T1_CMP);
+
+	ret = setup_irq(irq1, &owl_timer_irq);
+	if (ret) {
+		pr_warn("failed to setup irq %d\n", irq1);
+		return ret;
+	}

s/setup_irq/request_irq/

Care to explain? setup_irq has 32 hits vs. 28 for request_irq.

The function setup_irq takes an irqaction as parameter. That forces all the
drivers to declare a structure, so for a multiple platforms support (aka single
kernel image), there are multiple structures declaration for nothing. The
function request_irq allocates the structure and then call setup_irq.

So now, request_irq is used in place of setup_irq.

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+
+	owl_clockevent.cpumask = cpumask_of(0);
+	owl_clockevent.irq = irq1;
+
+	clockevents_config_and_register(&owl_clockevent, rate,
+					0xf, 0xffffffff);
+
+	return 0;
+}
+CLOCKSOURCE_OF_DECLARE(owl, "actions,owl-timer", owl_timer_init);

Do you spot anything functionally wrong in this driver? Despite adding
this new driver, I am only getting the following additional earlycon output:

[    0.000029] sched_clock: 32 bits at 24MHz, resolution 41ns, wraps
every 89478484971ns
[    0.007888] clocksource: timer: mask: 0xffffffff max_cycles:
0xffffffff, max_idle_ns: 79635851949 ns
[    0.017748] Console: colour dummy device 80x30
[    0.022243] Calibrating delay loop...
[    0.030895] random: fast init done
[    0.231021] random: crng init done

For S900 I'm using the generic timer instead.

I don't get the issue, can you elaborate ?

Thanks

  -- Daniel


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