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[2001:14ba:16e2:8300::3]) by smtp.gmail.com with ESMTPSA id t15sm269409ljk.99.2021.05.20.05.00.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 May 2021 05:00:41 -0700 (PDT) Message-ID: Subject: Re: [PATCH 1/2] gpio: regmap: Support few IC specific operations From: Matti Vaittinen Reply-To: matti.vaittinen@fi.rohmeurope.com To: Michael Walle Cc: Linus Walleij , Bartosz Golaszewski , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, linux-power@fi.rohmeurope.com In-Reply-To: <7d6f71e0a79e6ccd2a9f69be189993a9@walle.cc> References: <09091e75157ea28dcad1605008532016304356a4.1621509932.git.matti.vaittinen@fi.rohmeurope.com> <7d6f71e0a79e6ccd2a9f69be189993a9@walle.cc> Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Date: Thu, 20 May 2021 15:00:35 +0300 User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2021-05-20 at 13:42 +0200, Michael Walle wrote: > Hi Matti, > > Am 2021-05-20 13:28, schrieb Matti Vaittinen: > > The set_config and init_valid_mask GPIO operations are usually very > > IC > > specific. Allow IC drivers to provide these custom operations at > > gpio-regmap registration. > > > > Signed-off-by: Matti Vaittinen > > --- > > drivers/gpio/gpio-regmap.c | 49 > > +++++++++++++++++++++++++++++++++++++ > > include/linux/gpio/regmap.h | 13 ++++++++++ > > 2 files changed, 62 insertions(+) > > > > diff --git a/drivers/gpio/gpio-regmap.c b/drivers/gpio/gpio- > > regmap.c > > index 134cedf151a7..315285cacd3f 100644 > > --- a/drivers/gpio/gpio-regmap.c > > +++ b/drivers/gpio/gpio-regmap.c > > @@ -27,6 +27,10 @@ struct gpio_regmap { > > int (*reg_mask_xlate)(struct gpio_regmap *gpio, unsigned int > > base, > > unsigned int offset, unsigned int *reg, > > unsigned int *mask); > > + int (*set_config)(struct regmap *regmap, void *drvdata, > > + unsigned int offset, unsigned long config); > > + int (*init_valid_mask)(struct regmap *regmap, void *drvdata, > > + unsigned long *valid_mask, unsigned int > > ngpios); > > Maybe we should also make the first argument a "struct gpio_regmap" > and provide a new gpio_regmap_get_regmap(struct gpio_regmap). Thus > having a similar api as for the reg_mask_xlate(). Andy? I don't really see the reason of making this any more complicated for IC drivers. If we don't open the struct gpio_regmap to IC drivers - then they never need the struct gpio_regmap pointer itself but each IC driver would need to do some unnecessary function call (gpio_regmap_get_regmap() in this case). I'd say that would be unnecessary bloat. > > > void *driver_data; > > }; > > @@ -39,6 +43,43 @@ static unsigned int gpio_regmap_addr(unsigned > > int > > addr) > > return addr; > > } > > > > +static int regmap_gpio_init_valid_mask(struct gpio_chip *gc, > > + unsigned long *valid_mask, > > + unsigned int ngpios) > > +{ > > + struct gpio_regmap *gpio; > > + void *drvdata; > > + > > + gpio = gpiochip_get_data(gc); > > + > > + if (!gpio->init_valid_mask) { > > + WARN_ON(!gpio->init_valid_mask); > > + return -EINVAL; > > + } > > Why not the following? > > if (!gpio->init_valid_mask) > return 0; It just feels like an error if regmap_gpio_init_valid_mask() is ever called by core without having the gpio->init_valid_mask set. Probably this would mean that the someone has errorneously modified the gpio- >init_valid_mask set after gpio_regmap registration - whih smells like a problem. Thus the WARN() sounds like a correct course of action to me. (I may be wrong though - see below) > Thus copying the behavior of gpiolib. I must admit I didn't check how this is implemented in gpiolib. But the gpio_chip's init_valid_mask should not be set if regmap_gpio_config does not have valid init_valid_mask pointer at registration. Thus it smells like an error to me if the GPIO core calls the regmap_gpio_init_valid_mask() and regmap_gpio has not set the init_valid_mask pointer. But as I said, I haven't looked in gpiolib for this so I may be wrong. > > > + > > + drvdata = gpio_regmap_get_drvdata(gpio); > > + > > + return gpio->init_valid_mask(gpio->regmap, drvdata, > > valid_mask, > > ngpios); > > +} > > + > > +static int gpio_regmap_set_config(struct gpio_chip *gc, unsigned > > int > > offset, > > + unsigned long config) > > +{ > > + struct gpio_regmap *gpio; > > + void *drvdata; > > + > > + gpio = gpiochip_get_data(gc); > > + > > + if (!gpio->set_config) { > > + WARN_ON(!gpio->set_config); > > + return -EINVAL; > > + } > > same here, return -ENOTSUPP. As above - if (!gpio->set_config) { the gpio-core should never call gpio_regmap_set_config() if the } Maybe I should add a comment to clarify the WARN() ? > > > + > > + drvdata = gpio_regmap_get_drvdata(gpio); > > + > > + return gpio->set_config(gpio->regmap, drvdata, offset, config); > > +} > > + > > static int gpio_regmap_simple_xlate(struct gpio_regmap *gpio, > > unsigned int base, unsigned int > > offset, > > unsigned int *reg, unsigned int > > *mask) > > @@ -235,6 +276,8 @@ struct gpio_regmap *gpio_regmap_register(const > > struct gpio_regmap_config *config > > gpio->reg_clr_base = config->reg_clr_base; > > gpio->reg_dir_in_base = config->reg_dir_in_base; > > gpio->reg_dir_out_base = config->reg_dir_out_base; > > + gpio->set_config = config->set_config; > > + gpio->init_valid_mask = config->init_valid_mask; > > > > /* if not set, assume there is only one register */ > > if (!gpio->ngpio_per_reg) > > @@ -253,6 +296,10 @@ struct gpio_regmap *gpio_regmap_register(const > > struct gpio_regmap_config *config > > chip->ngpio = config->ngpio; > > chip->names = config->names; > > chip->label = config->label ?: dev_name(config->parent); > > + if (gpio->set_config) > > + chip->set_config = gpio_regmap_set_config; > > + if (gpio->init_valid_mask) > > + chip->init_valid_mask = regmap_gpio_init_valid_mask; > > > > #if defined(CONFIG_OF_GPIO) > > /* gpiolib will use of_node of the parent if chip->of_node is > > NULL */ > > @@ -280,6 +327,8 @@ struct gpio_regmap *gpio_regmap_register(const > > struct gpio_regmap_config *config > > chip->direction_output = gpio_regmap_direction_output; > > } > > > > + gpio_regmap_set_drvdata(gpio, config->drvdata); > > I'm wondering if we need the gpio_regmap_set_drvdata() anymore or if > we can just drop it entirely. I wouldn't drop it. I think there _may_ be cases where the drvdata is set only after the registration. (Just my gut-feeling, I may be wrong though) Best Regards Matti Vaittinen -- Matti Vaittinen, Linux device drivers ROHM Semiconductors, Finland SWDC Kiviharjunlenkki 1E 90220 OULU FINLAND ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~ Simon says - in Latin please. "non cogito me" dixit Rene Descarte, deinde evanescavit (Thanks for the translation Simon)