From: Paul Cercueil <paul@crapouillou.net> To: Lee Jones <lee.jones@linaro.org> Cc: Rob Herring <robh+dt@kernel.org>, Mark Rutland <mark.rutland@arm.com>, Ralf Baechle <ralf@linux-mips.org>, Paul Burton <paul.burton@mips.com>, James Hogan <jhogan@kernel.org>, Jonathan Corbet <corbet@lwn.net>, Daniel Lezcano <daniel.lezcano@linaro.org>, Thomas Gleixner <tglx@linutronix.de>, Michael Turquette <mturquette@baylibre.com>, Stephen Boyd <sboyd@kernel.org>, Jason Cooper <jason@lakedaemon.net>, Marc Zyngier <marc.zyngier@arm.com>, Mathieu Malaterre <malat@debian.org>, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-mips@vger.kernel.org, linux-doc@vger.kernel.org, linux-clk@vger.kernel.org, od@zcrc.me Subject: Re: [PATCH v12 04/13] mfd: Add Ingenic TCU driver Date: Thu, 27 Jun 2019 10:49:47 +0200 Message-ID: <1561625387.1745.0@crapouillou.net> (raw) In-Reply-To: <20190627065808.GY21119@dell> Le jeu. 27 juin 2019 à 8:58, Lee Jones <lee.jones@linaro.org> a écrit : > On Wed, 26 Jun 2019, Paul Cercueil wrote: >> Le mer. 26 juin 2019 à 15:18, Lee Jones <lee.jones@linaro.org> a >> écrit : >> > On Tue, 21 May 2019, Paul Cercueil wrote: >> > >> > > This driver will provide a regmap that can be retrieved very >> early >> > > in >> > > the boot process through the API function >> ingenic_tcu_get_regmap(). >> > > >> > > Additionally, it will call devm_of_platform_populate() so that >> all >> > > the >> > > children devices will be probed. >> > > >> > > Signed-off-by: Paul Cercueil <paul@crapouillou.net> >> > > --- >> > > >> > > Notes: >> > > v12: New patch >> > > >> > > drivers/mfd/Kconfig | 8 +++ >> > > drivers/mfd/Makefile | 1 + >> > > drivers/mfd/ingenic-tcu.c | 113 >> > > ++++++++++++++++++++++++++++++++ >> > > include/linux/mfd/ingenic-tcu.h | 8 +++ >> > > 4 files changed, 130 insertions(+) >> > > create mode 100644 drivers/mfd/ingenic-tcu.c > > [...] > >> > > +static struct regmap * __init ingenic_tcu_create_regmap(struct >> > > device_node *np) >> > > +{ >> > > + struct resource res; >> > > + void __iomem *base; >> > > + struct regmap *map; >> > > + >> > > + if (!of_match_node(ingenic_tcu_of_match, np)) >> > > + return ERR_PTR(-EINVAL); > > Drop this check. > >> > > + base = of_io_request_and_map(np, 0, "TCU"); >> > > + if (IS_ERR(base)) >> > > + return ERR_PTR(PTR_ERR(base)); >> > > + >> > > + map = regmap_init_mmio(NULL, base, >> &ingenic_tcu_regmap_config); >> > > + if (IS_ERR(map)) >> > > + goto err_iounmap; > > Place this inside probe(). > >> > > + return map; >> > > + >> > > +err_iounmap: >> > > + iounmap(base); >> > > + of_address_to_resource(np, 0, &res); >> > > + release_mem_region(res.start, resource_size(&res)); >> > > + >> > > + return map; >> > > +} >> > >> > Why does this need to be set-up earlier than probe()? >> >> See the explanation below. > > I think the answer is, it doesn't. > >> > > +static int __init ingenic_tcu_probe(struct platform_device >> *pdev) >> > > +{ >> > > + struct regmap *map = >> ingenic_tcu_get_regmap(pdev->dev.of_node); >> > > + >> > > + platform_set_drvdata(pdev, map); >> > > + >> > > + regmap_attach_dev(&pdev->dev, map, >> &ingenic_tcu_regmap_config); >> > > + >> > > + return devm_of_platform_populate(&pdev->dev); >> > > +} >> > > + >> > > +static struct platform_driver ingenic_tcu_driver = { >> > > + .driver = { >> > > + .name = "ingenic-tcu", >> > > + .of_match_table = ingenic_tcu_of_match, >> > > + }, >> > > +}; >> > > + >> > > +static int __init ingenic_tcu_platform_init(void) >> > > +{ >> > > + return platform_driver_probe(&ingenic_tcu_driver, >> > > + ingenic_tcu_probe); >> > >> > What? Why? >> >> The device driver probed here will populate the children devices, >> which will be able to retrieve the pointer to the regmap through >> device_get_regmap(dev->parent). > > I've never heard of this call. Where is it? dev_get_regmap, in <linux/regmap.h>. >> The children devices are normal platform drivers that can be probed >> the normal way. These are the PWM driver, the watchdog driver, and >> the >> OST (OS Timer) clocksource driver, all part of the same hardware >> block >> (the Timer/Counter Unit or TCU). > > If they are normal devices, then there is no need to roll your own > regmap-getter implementation like this. > >> > > +} >> > > +subsys_initcall(ingenic_tcu_platform_init); >> > > + >> > > +struct regmap * __init ingenic_tcu_get_regmap(struct >> device_node >> > > *np) >> > > +{ >> > > + if (!tcu_regmap) >> > > + tcu_regmap = ingenic_tcu_create_regmap(np); >> > > + >> > > + return tcu_regmap; >> > > +} >> > >> > This makes me pretty uncomfortable. >> > >> > What calls it? >> >> The TCU IRQ driver (patch [06/13]), clocks driver (patch [05/13]), >> and the >> non-OST clocksource driver (patch [07/13]) all probe very early in >> the boot >> process, and share the same devicetree node. They call this >> function to get >> a pointer to the regmap. > > Horrible! > > Instead, you should send it through platform_set_drvdata() and collect > it in the child drivers with platform_get_drvdata(dev->parent). The IRQ, clocks and clocksource driver do NOT have a "struct device" to begin with. They are not platform drivers, and cannot be platform drivers, as they must register so early in the boot process, before "struct device" is even a thing. All they get is a pointer to the same devicetree node. Since all of these have to use the same registers, they need to use a shared regmap, which they obtain by calling ingenic_tcu_get_regmap() below. Then, when this driver's probe gets called, the regmap is retrieved and attached to the struct device, and then the children devices will be probed: the watchdog device, the PWM device, the OST device. These three will retrieve the regmap by calling dev_get_regmap(dev->parent, NULL). >> > > +bool ingenic_tcu_pwm_can_use_chn(struct device *dev, unsigned >> int >> > > channel) >> > > +{ >> > > + const struct ingenic_soc_info *soc = >> > > device_get_match_data(dev->parent); >> > > + >> > > + /* Enable all TCU channels for PWM use by default except >> channels >> > > 0/1 */ >> > > + u32 pwm_channels_mask = GENMASK(soc->num_channels - 1, 2); >> > > + >> > > + device_property_read_u32(dev->parent, >> "ingenic,pwm-channels-mask", >> > > + &pwm_channels_mask); > > Doesn't this call overwrite the previous assignment above? Yes, that's intended. You have a default value, that can be overriden by a device property. >> > > + return !!(pwm_channels_mask & BIT(channel)); >> > > +} >> > > +EXPORT_SYMBOL_GPL(ingenic_tcu_pwm_can_use_chn); > > Where is this called from? This is called from the PWM driver. > I think this needs a review by the DT guys. Rob already acked the bindings, which describe this property. >> > > diff --git a/include/linux/mfd/ingenic-tcu.h >> > > b/include/linux/mfd/ingenic-tcu.h >> > > index 2083fa20821d..21df23916cd2 100644 >> > > --- a/include/linux/mfd/ingenic-tcu.h >> > > +++ b/include/linux/mfd/ingenic-tcu.h >> > > @@ -6,6 +6,11 @@ >> > > #define __LINUX_MFD_INGENIC_TCU_H_ >> > > >> > > #include <linux/bitops.h> >> > > +#include <linux/init.h> >> > > + >> > > +struct device; >> > > +struct device_node; >> > > +struct regmap; >> > > >> > > #define TCU_REG_WDT_TDR 0x00 >> > > #define TCU_REG_WDT_TCER 0x04 >> > > @@ -53,4 +58,7 @@ >> > > #define TCU_REG_TCNTc(c) (TCU_REG_TCNT0 + ((c) * >> > > TCU_CHANNEL_STRIDE)) >> > > #define TCU_REG_TCSRc(c) (TCU_REG_TCSR0 + ((c) * >> > > TCU_CHANNEL_STRIDE)) >> > > >> > > +struct regmap * __init ingenic_tcu_get_regmap(struct >> device_node >> > > *np); >> > > +bool ingenic_tcu_pwm_can_use_chn(struct device *dev, unsigned >> int >> > > channel); >> > > + >> > > #endif /* __LINUX_MFD_INGENIC_TCU_H_ */ >> > >> >> > > -- > Lee Jones [李琼斯] > Linaro Services Technical Lead > Linaro.org │ Open source software for ARM SoCs > Follow Linaro: Facebook | Twitter | Blog
next prev parent reply index Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-05-21 14:51 Ingenic Timer/Counter Unit (TCU) patchset v12 Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 01/13] dt-bindings: ingenic: Add DT bindings for TCU clocks Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 02/13] doc: Add doc for the Ingenic TCU hardware Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 03/13] dt-bindings: Add doc for the Ingenic TCU drivers Paul Cercueil 2019-05-24 20:21 ` Rob Herring 2019-05-25 19:13 ` Paul Cercueil 2019-06-11 14:57 ` Rob Herring 2019-05-21 14:51 ` [PATCH v12 04/13] mfd: Add Ingenic TCU driver Paul Cercueil 2019-06-22 12:21 ` Paul Cercueil 2019-06-26 13:18 ` Lee Jones 2019-06-26 13:55 ` Paul Cercueil 2019-06-27 6:58 ` Lee Jones 2019-06-27 8:49 ` Paul Cercueil [this message] 2019-06-27 9:01 ` Lee Jones 2019-06-27 9:19 ` Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 05/13] clk: ingenic: Add driver for the TCU clocks Paul Cercueil 2019-06-07 21:28 ` Stephen Boyd 2019-06-07 21:59 ` Paul Cercueil 2019-06-07 22:50 ` Stephen Boyd 2019-05-21 14:51 ` [PATCH v12 06/13] irqchip: Add irq-ingenic-tcu driver Paul Cercueil 2019-06-22 12:22 ` Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 07/13] clocksource: Add a new timer-ingenic driver Paul Cercueil 2019-06-22 12:23 ` Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 08/13] clk: jz4740: Add TCU clock Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 09/13] MIPS: jz4740: Add DTS nodes for the TCU drivers Paul Cercueil 2019-05-22 9:21 ` Mathieu Malaterre 2019-05-22 11:15 ` Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 10/13] MIPS: qi_lb60: Reduce system timer and clocksource to 750 kHz Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 11/13] MIPS: CI20: Reduce system timer and clocksource to 3 MHz Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 12/13] MIPS: GCW0: Reduce system timer and clocksource to 750 kHz Paul Cercueil 2019-05-21 14:51 ` [PATCH v12 13/13] MIPS: jz4740: Drop obsolete code Paul Cercueil 2019-05-27 11:39 ` Ingenic Timer/Counter Unit (TCU) patchset v12 Mathieu Malaterre
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