Messages in this thread | | | Date | Wed, 15 Feb 2023 13:18:49 +0000 | From | Sudeep Holla <> | Subject | Re: [PATCH v2 4/4] clocksource/drivers/timer-mediatek: Make timer-mediatek become loadable module |
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On Wed, Feb 15, 2023 at 01:43:19PM +0100, AngeloGioacchino Del Regno wrote: > Il 14/02/23 23:20, Sudeep Holla ha scritto: > > On Tue, Feb 14, 2023 at 06:53:14PM +0800, walter.chang@mediatek.com wrote: > > > From: Chun-Hung Wu <chun-hung.wu@mediatek.com> > > > > > > Make the timer-mediatek driver which can register > > > an always-on timer as tick_broadcast_device on > > > MediaTek SoCs become loadable module in GKI. > > > > > > Signed-off-by: Chun-Hung Wu <chun-hung.wu@mediatek.com> > > > --- > > > drivers/clocksource/Kconfig | 2 +- > > > drivers/clocksource/timer-mediatek.c | 43 ++++++++++++++++++++++++++++ > > > 2 files changed, 44 insertions(+), 1 deletion(-) > > > > [...] > > > > > diff --git a/drivers/clocksource/timer-mediatek.c b/drivers/clocksource/timer-mediatek.c > > > index d5b29fd03ca2..3358758ea694 100644 > > > --- a/drivers/clocksource/timer-mediatek.c > > > +++ b/drivers/clocksource/timer-mediatek.c > > > > [...] > > > > > +static const struct of_device_id mtk_timer_match_table[] = { > > > + { > > > + .compatible = "mediatek,mt6577-timer", > > > + .data = mtk_gpt_init, > > > + }, > > > + { > > > + .compatible = "mediatek,mt6765-timer", > > > + .data = mtk_syst_init, > > > + }, > > > + { > > > + .compatible = "mediatek,mt6795-systimer", > > > + .data = mtk_cpux_init, > > > + }, > > > + {} > > > +}; > > > + > > > +static struct platform_driver mtk_timer_driver = { > > > + .probe = mtk_timer_probe, > > > + .driver = { > > > + .name = "mtk-timer", > > > + .of_match_table = mtk_timer_match_table, > > > + }, > > > +}; > > > +module_platform_driver(mtk_timer_driver); > > > + > > > +MODULE_DESCRIPTION("MediaTek Module Timer driver"); > > > +MODULE_LICENSE("GPL v2"); > > > +#else > > > TIMER_OF_DECLARE(mtk_mt6577, "mediatek,mt6577-timer", mtk_gpt_init); > > > TIMER_OF_DECLARE(mtk_mt6765, "mediatek,mt6765-timer", mtk_syst_init); > > > TIMER_OF_DECLARE(mtk_mt6795, "mediatek,mt6795-systimer", mtk_cpux_init); > > > > Why do you need these ? If this driver can work as a module, it can be > > built-in module and doesn't need to be initialised early using of_timer_init > > (can't recall the exact name) > > > > Some platforms need early initialization; this is seen on ones for which the > bootloader does not initialize the "CPUXGPT" timer, which is used as the ARM > arch timer. (No, on those platforms you can't upgrade the bootloader, as it's > signed with a OEM key which is not obtainable, and signature verified earlier > in the bootchain). >
Is this arm32 or arm64 platform? Do you mean that these platforms don't have working architected timers ?
Quick grep suggests the below list of platforms/SoC:
| arch/arm64/boot/dts/mediatek/mt6795.dtsi | arch/arm64/boot/dts/mediatek/mt8173.dtsi | arch/arm64/boot/dts/mediatek/mt8183.dtsi | arch/arm64/boot/dts/mediatek/mt8186.dtsi | arch/arm64/boot/dts/mediatek/mt8192.dtsi | arch/arm64/boot/dts/mediatek/mt8195.dtsi | arch/arm64/boot/dts/mediatek/mt8516.dtsi | arch/arm/boot/dts/mt7623.dtsi | arch/arm/boot/dts/mt7629.dtsi | arch/arm/boot/dts/mt8127.dtsi | arch/arm/boot/dts/mt8135.dtsi
All the above has architected timers and can have the other timer initialised at module_initcall level.
| arch/arm/boot/dts/mt2701.dtsi | arch/arm/boot/dts/mt6580.dtsi | arch/arm/boot/dts/mt6582.dtsi | arch/arm/boot/dts/mt6589.dtsi | arch/arm/boot/dts/mt6592.dtsi
The above ones have cortex-a7 but still don't have architected timers listed in the DT. Anyways all use "mediatek,mt6577-timer", so except that other 2 can be dropped from the else and force them to be initialised later.
> As a matter of fact (and somehow obvious), on those platforms (for example, > MT6795.. but many other as well, really), you *need* this driver to be > built-in and, well, initialize the CPUX timer as early as possible :-) >
Built-in is not a problem, you can still remove TIMER_OF_DECLARE as the initialisation happens later at module_initcall level.
-- Regards, Sudeep
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