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Date: Wed, 25 Apr 2018 18:57:30 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Javier Arteaga <javier@...tex.com>,
Lee Jones <lee.jones@...aro.org>
Cc: Dan O'Donovan <dan@...tex.com>,
Mika Westerberg <mika.westerberg@...ux.intel.com>,
Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
Linus Walleij <linus.walleij@...aro.org>,
Jacek Anaszewski <jacek.anaszewski@...il.com>,
Pavel Machek <pavel@....cz>, linux-gpio@...r.kernel.org,
linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH RESEND 1/3] mfd: upboard: Add UP2 platform
controller driver
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 <andriy.shevchenko@...ux.intel.com>
Intel Finland Oy
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