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Message-ID: <1bf2d9ad-325e-4b1d-8440-ddbc90eabc67@linaro.org>
Date: Tue, 25 Mar 2025 13:23:23 +0100
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Krzysztof Kozlowski <krzk@...nel.org>, tglx@...utronix.de
Cc: linux-kernel@...r.kernel.org, Thomas Fossati <thomas.fossati@...aro.org>,
Larisa Grigore <Larisa.Grigore@....com>,
Ghennadi Procopciuc <ghennadi.procopciuc@....com>,
Maxime Coquelin <mcoquelin.stm32@...il.com>,
Alexandre Torgue <alexandre.torgue@...s.st.com>,
"moderated list:ARM/STM32 ARCHITECTURE"
<linux-stm32@...md-mailman.stormreply.com>,
"moderated list:ARM/STM32 ARCHITECTURE"
<linux-arm-kernel@...ts.infradead.org>, dl-S32 <S32@....com>
Subject: Re: [PATCH 2/2] clocksource/drivers/nxp-timer: Add the System Timer
Module for the s32g platform
[Added s32@ list which I miss from the initial series]
On 25/03/2025 08:30, Krzysztof Kozlowski wrote:
> On 24/03/2025 11:00, Daniel Lezcano wrote:
>> +
>> +static int __init nxp_stm_clocksource_init(struct device *dev, const char *name,
>> + void __iomem *base, struct clk *clk)
>> +{
>> + struct stm_timer *stm_timer;
>> + int ret;
>> +
>> + stm_timer = devm_kzalloc(dev, sizeof(*stm_timer), GFP_KERNEL);
>> + if (!stm_timer)
>> + return -ENOMEM;
>> +
>> + stm_timer->base = base;
>> + stm_timer->rate = clk_get_rate(clk);
>> +
>> + stm_timer->scs.cs.name = name;
>
> You are aware that all node names will have exactly the same name? All
> of them will be called "timer"?
From the caller const char *name = of_node_full_name(np);
The names are:
"clocksource: Switched to clocksource stm@...1c000"
Or:
17: 24150 0 0 0 GICv3 57 Level
stm@...20000
18: 0 22680 0 0 GICv3 58 Level
stm@...24000
19: 0 0 24110 0 GICv3 59 Level
stm@...28000
20: 0 0 0 21164 GICv3 60 Level
stm@...1c000
And:
cat /sys/devices/system/clocksource/clocksource0/current_clocksource
stm@...1c000
cat /sys/devices/system/clockevents/clockevent*/current_device
stm@...20000
stm@...24000
stm@...28000
stm@...1c000
[ ... ]
>> +
>> +static int __init nxp_stm_timer_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + struct device_node *np = dev->of_node;
>> + struct stm_instances *stm_instances;
>> + const char *name = of_node_full_name(np);
>> + void __iomem *base;
>> + int irq, ret;
>> + struct clk *clk;
>> +
>> + stm_instances = (typeof(stm_instances))of_device_get_match_data(dev);
>
> No, you *cannot* drop the const. It's there on purpose. Match data
> should be const because it defines per variant differences. That's why
> the prototype of of_device_get_match_data() has such return type.
> You just want some global singleton, not match data.
>
>> + if (!stm_instances) {
>> + dev_err(dev, "No STM instances associated with a cpu");
>> + return -EINVAL;
>> + }
>> +
>> + base = devm_of_iomap(dev, np, 0, NULL);
>> + if (IS_ERR(base)) {
>> + dev_err(dev, "Failed to iomap %pOFn\n", np);
>
> You need to clean up the downstream code to match upstream. All of these
> should be return dev_err_probe().
Oh right, thanks for the reminder
>> + return PTR_ERR(base);
>> + }
>> +
>> + irq = irq_of_parse_and_map(np, 0);
>> + if (irq <= 0) {
>> + dev_err(dev, "Failed to parse and map IRQ: %d\n", irq);
>> + return -EINVAL;
>> + }
>> +
>> + clk = devm_clk_get(dev, NULL);
>> + if (IS_ERR(clk)) {
>> + dev_err(dev, "Clock not found\n");
>
> And this is clearly incorrect - spamming logs. Syntax is:
> return dev_err_probe
>
>> + return PTR_ERR(clk);
>> + }
>> +
>> + ret = clk_prepare_enable(clk);
>
> Drop, devm_clk_get_enabled.
>
>> + if (ret) {
>> + dev_err(dev, "Failed to enable STM timer clock: %d\n", ret);
>> + return ret;
>> + }
>> +
>> + if (!stm_instances->clocksource && (stm_instances->features & STM_CLKSRC)) {
>> +
>> + /*
>> + * First probed STM will be a clocksource
>> + */
>> + ret = nxp_stm_clocksource_init(dev, name, base, clk);
>> + if (ret)
>> + return ret;
>> + stm_instances->clocksource++;
>
> That's racy. Devices can be brought async, ideally. This should be
> rather idr or probably entire structure protected with a mutex.
Mmh, interesting. I never had to think about this problem before
Do you know at what moment the probing is parallelized ?
>> +static struct stm_instances s32g_stm_instances = { .features = STM_CLKSRC | STM_CLKEVT_PER_CPU };
>
> Missing const. Or misplaced - all file-scope static variables are
> declared at the top.
>
>> +
>> +static const struct of_device_id nxp_stm_of_match[] = {
>> + { .compatible = "nxp,s32g2-stm", &s32g_stm_instances },
>> + { }
>> +};
>> +MODULE_DEVICE_TABLE(of, nxp_stm_of_match);
>> +
>> +static struct platform_driver nxp_stm_probe = {
>> + .probe = nxp_stm_timer_probe,
>> + .driver = {
>> + .name = "nxp-stm",
>> + .of_match_table = of_match_ptr(nxp_stm_of_match),
>
> Drop of_match_ptr, you have here warnings.
>
>> + },
>> +};
>> +module_platform_driver(nxp_stm_probe);
>> +
>> +MODULE_DESCRIPTION("NXP System Timer Module driver");
>> +MODULE_LICENSE("GPL");
Thanks for the review
-- Daniel
--
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