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charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1561625387.1745.0@crapouillou.net> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 27 Jun 2019, Paul Cercueil wrote: > Le jeu. 27 juin 2019 à 8:58, Lee Jones a écrit : > > On Wed, 26 Jun 2019, Paul Cercueil wrote: > > > Le mer. 26 juin 2019 à 15:18, Lee Jones 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 > > > > > --- > > > > > > > > > > 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 . > > > > 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. Can you send your v14, as you intended. I will re-review it with new eyes when you do. > > > > > +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. > > > > > + 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? -- Lee Jones [李琼斯] Linaro Services Technical Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog