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 11:19:48 +0200 Message-ID: <1561627188.1745.1@crapouillou.net> (raw) In-Reply-To: <20190627090102.GA2000@dell> Le jeu. 27 juin 2019 à 11:01, Lee Jones <lee.jones@linaro.org> a écrit : > On Thu, 27 Jun 2019, Paul Cercueil wrote: >> 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). > > That makes sense. > > This explanation certainly belongs in the commit log. Right. > Can you send your v14, as you intended. I will re-review it with new > eyes when you do. Could you review v13 instead? v14 will be a v13 with tiny teeny non-code fixes (delete some newlines, replace %i with %d, and convert the documentation from .txt to .rst). >> > > > > +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. > > You should provide a comment here to make your intentions clear. Ok. >> > > > > + 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. > > Why can't it live in the PWM driver? It totally can. I'll move it there. > > -- > 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 2019-06-27 9:01 ` Lee Jones 2019-06-27 9:19 ` Paul Cercueil [this message] 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
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=1561627188.1745.1@crapouillou.net \ --to=paul@crapouillou.net \ --cc=corbet@lwn.net \ --cc=daniel.lezcano@linaro.org \ --cc=devicetree@vger.kernel.org \ --cc=jason@lakedaemon.net \ --cc=jhogan@kernel.org \ --cc=lee.jones@linaro.org \ --cc=linux-clk@vger.kernel.org \ --cc=linux-doc@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-mips@vger.kernel.org \ --cc=malat@debian.org \ --cc=marc.zyngier@arm.com \ --cc=mark.rutland@arm.com \ --cc=mturquette@baylibre.com \ --cc=od@zcrc.me \ --cc=paul.burton@mips.com \ --cc=ralf@linux-mips.org \ --cc=robh+dt@kernel.org \ --cc=sboyd@kernel.org \ --cc=tglx@linutronix.de \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
Linux-MIPS Archive on lore.kernel.org Archives are clonable: git clone --mirror https://lore.kernel.org/linux-mips/0 linux-mips/git/0.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 linux-mips linux-mips/ https://lore.kernel.org/linux-mips \ linux-mips@vger.kernel.org public-inbox-index linux-mips Example config snippet for mirrors Newsgroup available over NNTP: nntp://nntp.lore.kernel.org/org.kernel.vger.linux-mips AGPL code for this site: git clone https://public-inbox.org/public-inbox.git