From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andy Shevchenko Subject: Re: [RFC PATCH RESEND 1/3] mfd: upboard: Add UP2 platform controller driver Date: Wed, 25 Apr 2018 18:57:30 +0300 Message-ID: <1524671850.21176.585.camel@linux.intel.com> References: <20180421085009.28773-1-javier@emutex.com> <20180421085009.28773-2-javier@emutex.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20180421085009.28773-2-javier@emutex.com> Sender: linux-kernel-owner@vger.kernel.org To: Javier Arteaga , Lee Jones Cc: Dan O'Donovan , Mika Westerberg , Heikki Krogerus , Linus Walleij , Jacek Anaszewski , Pavel Machek , linux-gpio@vger.kernel.org, linux-leds@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-gpio@vger.kernel.org On Sat, 2018-04-21 at 09:50 +0100, Javier Arteaga wrote: > UP Squared (UP2) is a x86 SBC from AAEON based on Intel Apollo Lake. > +config MFD_UPBOARD > + tristate "UP Squared" > + depends on ACPI > + depends on GPIOLIB > + select MFD_CORE > + select REGMAP > + help > + If you say yes here you get support for the platform > controller > + of the UP Squared single-board computer. > + > + This driver provides common support for accessing the > device, > + additional drivers must be enabled in order to use the > + functionality of the device. > + > + This driver can also be built as a module. If so, the > module > + will be called upboard. "upboard" > > +static int upboard_read(void *context, unsigned int reg, unsigned int > *val) > +{ > + const struct upboard * const upboard = context; > + int i; > + > + gpiod_set_value(upboard->clear_gpio, 0); > + gpiod_set_value(upboard->clear_gpio, 1); > + > + reg |= UPBOARD_READ_FLAG; > + > + for (i = UPBOARD_ADDRESS_SIZE; i >= 0; i--) { > + gpiod_set_value(upboard->strobe_gpio, 0); > + gpiod_set_value(upboard->datain_gpio, (reg >> i) & > 0x1); > + gpiod_set_value(upboard->strobe_gpio, 1); > + } > + > + gpiod_set_value(upboard->strobe_gpio, 0); > + *val = 0; > + > + for (i = UPBOARD_REGISTER_SIZE - 1; i >= 0; i--) { > + gpiod_set_value(upboard->strobe_gpio, 1); > + gpiod_set_value(upboard->strobe_gpio, 0); > + *val |= gpiod_get_value(upboard->dataout_gpio) << i; > + } > + > + gpiod_set_value(upboard->strobe_gpio, 1); Can't you rewrite this like for (addr) { strobe(0) data(x) strobe(1) } for (register) { strobe(0) val = data(x) strobe(1) } val &= BIT(register_size); strobe(0) ? > + > + return 0; > +}; > + > +static int upboard_write(void *context, unsigned int reg, unsigned > int val) > +{ > + const struct upboard * const upboard = context; > + int i; > + > + gpiod_set_value(upboard->clear_gpio, 0); > + gpiod_set_value(upboard->clear_gpio, 1); > + > + for (i = UPBOARD_ADDRESS_SIZE; i >= 0; i--) { > + gpiod_set_value(upboard->strobe_gpio, 0); > + gpiod_set_value(upboard->datain_gpio, (reg >> i) & > 0x1); > + gpiod_set_value(upboard->strobe_gpio, 1); > + } > + > + gpiod_set_value(upboard->strobe_gpio, 0); > + > + for (i = UPBOARD_REGISTER_SIZE - 1; i >= 0; i--) { > + gpiod_set_value(upboard->datain_gpio, (val >> i) & > 0x1); > + gpiod_set_value(upboard->strobe_gpio, 1); > + gpiod_set_value(upboard->strobe_gpio, 0); > + } > + > + gpiod_set_value(upboard->strobe_gpio, 1); Similar here: for (addr) { strobe(0) data(x) strobe(1) } for (register) { strobe(0) data(x) strobe(1) } strobe(0) strobe(1) ? > + > + return 0; > +}; Moreover these two functions have duplications, i.e. static ... upboard_clear() { clear(0) clear(1) } static ... upboard_set_address() { for (addr) { ... } } Additional question is about spi-bitbang and i2c-gpio. Can one of them be utilized here? Why not? > +struct upboard_data { > + const struct regmap_config *regmapconf; > + const struct mfd_cell *cells; > + size_t ncells; > +}; > +static int upboard_init_gpio(struct upboard *upboard) > +{ > + struct gpio_desc *enable_gpio; > + > + enable_gpio = devm_gpiod_get(upboard->dev, "enable", > GPIOD_OUT_LOW); > + if (IS_ERR(enable_gpio)) > + return PTR_ERR(enable_gpio); > + gpiod_set_value(enable_gpio, 1); When do you disable it? Why not? > + return 0; > +} > + > +static int upboard_check_supported(struct upboard *upboard) > +{ > + const unsigned int AAEON_MANUFACTURER_ID = 0x01; > + const unsigned int SUPPORTED_FW_MAJOR = 0x0; Why to hide here instead of putting at the top of file as defined constants? > + unsigned int platform_id, manufacturer_id; > + unsigned int firmware_id, build, major, minor, patch; > + int ret; > + build = (firmware_id >> 12) & 0xf; > + major = (firmware_id >> 8) & 0xf; > + minor = (firmware_id >> 4) & 0xf; > + patch = firmware_id & 0xf; For style purposes you can use (firmware >> 0) & 0xf here > +static int upboard_probe(struct platform_device *pdev) > +{ > + struct upboard *upboard; > + const struct acpi_device_id *id; > + const struct upboard_data *upboard_data; > + int ret; > + id = acpi_match_device(upboard_acpi_match, &pdev->dev); > + if (!id) > + return -ENODEV; > + > + upboard_data = (const struct upboard_data *) id->driver_data; Use new API for that. > +MODULE_LICENSE("GPL"); License mismatch. > +#define UPBOARD_ADDRESS_SIZE 7 > +#define UPBOARD_REGISTER_SIZE 16 > +#define UPBOARD_READ_FLAG BIT(UPBOARD_ADDRESS_SIZE) It's not clear why this one is defined in this way. Comment is needed. -- Andy Shevchenko Intel Finland Oy