[V3,1/3] mfd: Add support for UP board CPLD/FPGA

The UP Squared board <http://www.upboard.com> implements certain
features (pin control, onboard LEDs or CEC) through an on-board CPLD/FPGA.

This mfd driver implements the line protocol to read and write registers
from the FPGA through regmap. The register address map is also included.

The UP Boards provide a few I/O pin headers (for both GPIO and
functions), including a 40-pin Raspberry Pi compatible header.

This patch implements support for the FPGA-based pin controller that
manages direction and enable state for those header pins.

Partial support UP boards:
* UP core + CREX
* UP core + CRST02

PATCH V3:
(1) fixed kernel test robot compiler warning

PATCH V2:
(1) Synchronizing upboard github to rc2
(2) Refer 2022/10/31 Lee Jones review, fixed some of the issues.

Signed-off-by: Javier Arteaga <javier@emutex.com>
[merge various fixes]
Signed-off-by: Nicola Lunghi <nicola.lunghi@emutex.com>
Signed-off-by: chengwei <larry.lai@yunjingtech.com>
---
 drivers/mfd/Kconfig              |  12 +
 drivers/mfd/Makefile             |   1 +
 drivers/mfd/upboard-fpga.c       | 620 +++++++++++++++++++++++++++++++
 include/linux/mfd/upboard-fpga.h |  56 +++
 4 files changed, 689 insertions(+)
 create mode 100644 drivers/mfd/upboard-fpga.c
 create mode 100644 include/linux/mfd/upboard-fpga.h

On Wed, 09 Nov 2022, chengwei wrote:

> The UP Squared board <http://www.upboard.com> implements certain
> features (pin control, onboard LEDs or CEC) through an on-board CPLD/FPGA.
> 
> This mfd driver implements the line protocol to read and write registers
> from the FPGA through regmap. The register address map is also included.
> 
> The UP Boards provide a few I/O pin headers (for both GPIO and
> functions), including a 40-pin Raspberry Pi compatible header.
> 
> This patch implements support for the FPGA-based pin controller that
> manages direction and enable state for those header pins.
> 
> Partial support UP boards:
> * UP core + CREX
> * UP core + CRST02
> 
> PATCH V3:
> (1) fixed kernel test robot compiler warning
> 
> PATCH V2:
> (1) Synchronizing upboard github to rc2
> (2) Refer 2022/10/31 Lee Jones review, fixed some of the issues.

The change log should be below the '---' below.

> Signed-off-by: Javier Arteaga <javier@emutex.com>
> [merge various fixes]

Drop this line please.

> Signed-off-by: Nicola Lunghi <nicola.lunghi@emutex.com>
> Signed-off-by: chengwei <larry.lai@yunjingtech.com>

Full name?

> ---
>  drivers/mfd/Kconfig              |  12 +
>  drivers/mfd/Makefile             |   1 +
>  drivers/mfd/upboard-fpga.c       | 620 +++++++++++++++++++++++++++++++
>  include/linux/mfd/upboard-fpga.h |  56 +++
>  4 files changed, 689 insertions(+)
>  create mode 100644 drivers/mfd/upboard-fpga.c
>  create mode 100644 include/linux/mfd/upboard-fpga.h
> 
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index abb58ab1a1a4..c1d72a70e5f2 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -2104,6 +2104,18 @@ config MFD_QCOM_PM8008
>  	  under it in the device tree. Additional drivers must be enabled in
>  	  order to use the functionality of the device.
>  
> +config MFD_UPBOARD_FPGA

INTEL?

> +	tristate "Support for the UP board FPGA"

Intel?

> +	select MFD_CORE
> +	depends on X86 && ACPI
> +	help
> +	  Select this option to enable the Intel AAEON UP and UP^2 on-board FPGA.
> +	  The UP board implements certain features (pin control, onboard LEDs or
> +	  CEC) through an on-board FPGA.
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called upboard-fpga.
> +
>  menu "Multimedia Capabilities Port drivers"
>  	depends on ARCH_SA1100
>  
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 858cacf659d6..d9d10e3664f7 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -250,6 +250,7 @@ obj-$(CONFIG_MFD_ALTERA_A10SR)	+= altera-a10sr.o
>  obj-$(CONFIG_MFD_ALTERA_SYSMGR) += altera-sysmgr.o
>  obj-$(CONFIG_MFD_STPMIC1)	+= stpmic1.o
>  obj-$(CONFIG_MFD_SUN4I_GPADC)	+= sun4i-gpadc.o
> +obj-$(CONFIG_MFD_UPBOARD_FPGA)	+= upboard-fpga.o
>  
>  obj-$(CONFIG_MFD_STM32_LPTIMER)	+= stm32-lptimer.o
>  obj-$(CONFIG_MFD_STM32_TIMERS) 	+= stm32-timers.o
> diff --git a/drivers/mfd/upboard-fpga.c b/drivers/mfd/upboard-fpga.c
> new file mode 100644
> index 000000000000..89d0d36d2d17
> --- /dev/null
> +++ b/drivers/mfd/upboard-fpga.c
> @@ -0,0 +1,620 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * UP Board main platform driver and FPGA configuration support

There are 1000's of different types of platform drivers in the kernel.

Core driver?

> + * Copyright (c) 2022, Emutex Ltd. All rights reserved.
> + *
> + * Author: Javier Arteaga <javier@emutex.com>
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/dmi.h>
> +#include <linux/gpio.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/upboard-fpga.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +struct upboard_fpga_data {
> +	const struct regmap_config *regmapconf;
> +	const struct mfd_cell *cells;
> +	size_t ncells;
> +};
> +
> +#define UPBOARD_LED_CELL(led_data, n)                       \
> +	MFD_CELL_BASIC("upboard-led", NULL, &led_data[(n)], \
> +		       sizeof(*(led_data)), (n))

Just use MFD_CELL_BASIC in-place for now.

> +#define AAEON_MANUFACTURER_ID 0x01
> +#define SUPPORTED_FW_MAJOR 0x0
> +#define MENUFACTURER_ID_MASK 0xFF
> +
> +#define FIRMWARE_ID_BUILD_OFFSET 12
> +#define FIRMWARE_ID_MAJOR_OFFSET 8
> +#define FIRMWARE_ID_MINOR_OFFSET 4
> +#define FIRMWARE_ID_PATCH_OFFSET 0
> +#define FIRMWARE_ID_MASK 0xF
> +
> +#define UPFPGA_QUIRK_UNINITIALISED  BIT(0)
> +#define UPFPGA_QUIRK_HRV1_IS_PROTO2 BIT(1)
> +#define UPFPGA_QUIRK_GPIO_LED       BIT(2)

Tab all of these values out please.  It hurts my OCD.

> +#define UPBOARD_DEVID 0

No, that's not what this means.

Please use the defines already provided for you.

> +/* UP-CREX carrier board for UP Core */
> +
> +/* same MAXV config as UP1 (proto2 release) */
> +#define upboard_upcore_crex_fpga_data upboard_up_fpga_data

Then just use upboard_up_fpga_data where needed.

> +#define APL_GPIO_218	507

Can you show the logic to convert one to the other?

> +/* UP board */

Doesn't look like it.  These functions are used for the ^2 version too.

> +static int upboard_fpga_read(void *context, unsigned int reg, unsigned int *val)
> +{
> +	struct upboard_fpga * const fpga = context;
> +	int i;
> +
> +	if (IS_ERR(fpga->clear_gpio))	//for none fpga boards

No C++ comments please.

Can you make that comment clearer, I don't understand.

> +		return 0;

So there is an error, but you're returning okay?

> +	gpiod_set_value(fpga->clear_gpio, 0);

What do all of these 0s and 1s do exactly?

> +	gpiod_set_value(fpga->clear_gpio, 1);
> +
> +	reg |= UPFPGA_READ_FLAG;
> +
> +	for (i = UPFPGA_ADDRESS_SIZE; i >= 0; i--) {
> +		gpiod_set_value(fpga->strobe_gpio, 0);
> +		gpiod_set_value(fpga->datain_gpio, (reg >> i) & 0x1);
> +		gpiod_set_value(fpga->strobe_gpio, 1);
> +	}

What's happening here?  Comments please.  Throughout ...

> +	gpiod_set_value(fpga->strobe_gpio, 0);
> +	*val = 0;
> +
> +	for (i = UPFPGA_REGISTER_SIZE - 1; i >= 0; i--) {
> +		gpiod_set_value(fpga->strobe_gpio, 1);
> +		gpiod_set_value(fpga->strobe_gpio, 0);
> +		*val |= gpiod_get_value(fpga->dataout_gpio) << i;
> +	}
> +
> +	gpiod_set_value(fpga->strobe_gpio, 1);
> +
> +	return 0;
> +}
> +
> +static int upboard_fpga_write(void *context, unsigned int reg, unsigned int val)
> +{
> +	struct upboard_fpga * const fpga = context;
> +	int i;
> +
> +	if (IS_ERR(fpga->clear_gpio))	//for none fpga boards
> +		return 0;
> +
> +	gpiod_set_value(fpga->clear_gpio, 0);
> +	gpiod_set_value(fpga->clear_gpio, 1);
> +
> +	for (i = UPFPGA_ADDRESS_SIZE; i >= 0; i--) {
> +		gpiod_set_value(fpga->strobe_gpio, 0);
> +		gpiod_set_value(fpga->datain_gpio, (reg >> i) & 0x1);
> +		gpiod_set_value(fpga->strobe_gpio, 1);
> +	}
> +
> +	gpiod_set_value(fpga->strobe_gpio, 0);
> +
> +	for (i = UPFPGA_REGISTER_SIZE - 1; i >= 0; i--) {
> +		gpiod_set_value(fpga->datain_gpio, (val >> i) & 0x1);
> +		gpiod_set_value(fpga->strobe_gpio, 1);
> +		gpiod_set_value(fpga->strobe_gpio, 0);
> +	}
> +
> +	gpiod_set_value(fpga->strobe_gpio, 1);
> +
> +	return 0;
> +}
> +
> +static const struct regmap_range upboard_up_readable_ranges[] = {
> +	regmap_reg_range(UPFPGA_REG_PLATFORM_ID, UPFPGA_REG_FIRMWARE_ID),
> +	regmap_reg_range(UPFPGA_REG_FUNC_EN0, UPFPGA_REG_FUNC_EN0),
> +	regmap_reg_range(UPFPGA_REG_GPIO_DIR0, UPFPGA_REG_GPIO_DIR1),
> +};
> +
> +static const struct regmap_range upboard_up_writable_ranges[] = {
> +	regmap_reg_range(UPFPGA_REG_FUNC_EN0, UPFPGA_REG_FUNC_EN0),
> +	regmap_reg_range(UPFPGA_REG_GPIO_DIR0, UPFPGA_REG_GPIO_DIR1),
> +};
> +
> +static const struct regmap_access_table upboard_up_readable_table = {
> +	.yes_ranges = upboard_up_readable_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(upboard_up_readable_ranges),
> +};
> +
> +static const struct regmap_access_table upboard_up_writable_table = {
> +	.yes_ranges = upboard_up_writable_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(upboard_up_writable_ranges),
> +};
> +
> +static const struct regmap_config upboard_up_regmap_config = {
> +	.reg_bits = UPFPGA_ADDRESS_SIZE,
> +	.val_bits = UPFPGA_REGISTER_SIZE,
> +	.max_register = UPFPGA_REG_MAX,
> +	.reg_read = upboard_fpga_read,
> +	.reg_write = upboard_fpga_write,
> +	.fast_io = false,
> +	.cache_type = REGCACHE_RBTREE,
> +	.rd_table = &upboard_up_readable_table,
> +	.wr_table = &upboard_up_writable_table,
> +};
> +
> +static struct upboard_led_data upboard_up_led_data[] = {
> +	{ .bit = 0, .colour = "yellow" },
> +	{ .bit = 1, .colour = "green" },
> +	{ .bit = 2, .colour = "red" },
> +};
> +
> +static const struct mfd_cell upboard_up_mfd_cells[] = {
> +	{ .name = "upboard-pinctrl" },
> +	UPBOARD_LED_CELL(upboard_up_led_data, 0),
> +	UPBOARD_LED_CELL(upboard_up_led_data, 1),
> +	UPBOARD_LED_CELL(upboard_up_led_data, 2),
> +};
> +
> +static const struct upboard_fpga_data upboard_up_fpga_data = {
> +	.regmapconf = &upboard_up_regmap_config,
> +	.cells = upboard_up_mfd_cells,
> +	.ncells = ARRAY_SIZE(upboard_up_mfd_cells),
> +};
> +
> +//UP-EHL

This comment begs more questions than it answers.

> +static const struct mfd_cell upboard_pinctrl_cells[] = {
> +	{ .name = "upboard-pinctrl" },
> +};
> +
> +static const struct upboard_fpga_data upboard_pinctrl_data = {
> +	.regmapconf = &upboard_up_regmap_config,
> +	.cells = upboard_pinctrl_cells,
> +	.ncells = ARRAY_SIZE(upboard_pinctrl_cells),
> +};
> +
> +/* UP^2 board */
> +
> +static const struct regmap_range upboard_up2_readable_ranges[] = {
> +	regmap_reg_range(UPFPGA_REG_PLATFORM_ID, UPFPGA_REG_FIRMWARE_ID),
> +	regmap_reg_range(UPFPGA_REG_FUNC_EN0, UPFPGA_REG_FUNC_EN1),
> +	regmap_reg_range(UPFPGA_REG_GPIO_EN0, UPFPGA_REG_GPIO_EN2),
> +	regmap_reg_range(UPFPGA_REG_GPIO_DIR0, UPFPGA_REG_GPIO_DIR2),
> +};
> +
> +static const struct regmap_range upboard_up2_writable_ranges[] = {
> +	regmap_reg_range(UPFPGA_REG_FUNC_EN0, UPFPGA_REG_FUNC_EN1),
> +	regmap_reg_range(UPFPGA_REG_GPIO_EN0, UPFPGA_REG_GPIO_EN2),
> +	regmap_reg_range(UPFPGA_REG_GPIO_DIR0, UPFPGA_REG_GPIO_DIR2),
> +};
> +
> +static const struct regmap_access_table upboard_up2_readable_table = {
> +	.yes_ranges = upboard_up2_readable_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(upboard_up2_readable_ranges),
> +};
> +
> +static const struct regmap_access_table upboard_up2_writable_table = {
> +	.yes_ranges = upboard_up2_writable_ranges,
> +	.n_yes_ranges = ARRAY_SIZE(upboard_up2_writable_ranges),
> +};
> +
> +static const struct regmap_config upboard_up2_regmap_config = {
> +	.reg_bits = UPFPGA_ADDRESS_SIZE,
> +	.val_bits = UPFPGA_REGISTER_SIZE,
> +	.max_register = UPFPGA_REG_MAX,
> +	.reg_read = upboard_fpga_read,
> +	.reg_write = upboard_fpga_write,
> +	.fast_io = false,
> +//	.cache_type = REGCACHE_NONE,

???

> +	.rd_table = &upboard_up2_readable_table,
> +	.wr_table = &upboard_up2_writable_table,
> +};
> +
> +static struct upboard_led_data upboard_up2_led_data[] = {
> +	{ .bit = 0, .colour = "blue" },
> +	{ .bit = 1, .colour = "yellow" },
> +	{ .bit = 2, .colour = "green" },
> +	{ .bit = 3, .colour = "red" },
> +};
> +
> +static const struct mfd_cell upboard_up2_mfd_cells[] = {
> +	{ .name = "upboard-pinctrl" },
> +	UPBOARD_LED_CELL(upboard_up2_led_data, 0),
> +	UPBOARD_LED_CELL(upboard_up2_led_data, 1),
> +	UPBOARD_LED_CELL(upboard_up2_led_data, 2),
> +	UPBOARD_LED_CELL(upboard_up2_led_data, 3),
> +};
> +
> +static const struct upboard_fpga_data upboard_up2_fpga_data = {
> +	.regmapconf = &upboard_up2_regmap_config,
> +	.cells = upboard_up2_mfd_cells,
> +	.ncells = ARRAY_SIZE(upboard_up2_mfd_cells),
> +};

You'd be better off getting rid of 'truct upboard_fpga_data'
altogether.

> +/* UP-CRST02 carrier board for UP Core */
> +
> +/* same MAX10 config as UP2, but same LED cells as UP1 */
> +static const struct upboard_fpga_data upboard_upcore_crst02_fpga_data = {
> +	.regmapconf = &upboard_up2_regmap_config,
> +	.cells = upboard_up_mfd_cells,
> +	.ncells = ARRAY_SIZE(upboard_up_mfd_cells),
> +};
> +
> +static struct gpio_led upboard_gpio_leds[] = {
> +	{
> +		.name = "upboard:blue:",
> +		.gpio = APL_GPIO_218,
> +		.default_state = LEDS_GPIO_DEFSTATE_KEEP,
> +	},
> +};
> +
> +static struct gpio_led_platform_data upboard_gpio_led_platform_data = {
> +	.num_leds = ARRAY_SIZE(upboard_gpio_leds),
> +	.leds = upboard_gpio_leds,
> +};
> +
> +static const struct mfd_cell upboard_gpio_led_cells[] = {
> +	MFD_CELL_BASIC("leds-gpio", NULL, &upboard_gpio_led_platform_data,
> +		       sizeof(upboard_gpio_led_platform_data), 0)
> +};
> +
> +static int __init upboard_fpga_gpio_init(struct upboard_fpga *fpga)
> +{
> +	enum gpiod_flags flags;
> +
> +	flags = fpga->uninitialised ? GPIOD_OUT_LOW : GPIOD_ASIS;
> +
> +	fpga->enable_gpio = devm_gpiod_get(fpga->dev, "enable", flags);
> +	if (IS_ERR(fpga->enable_gpio))
> +		return PTR_ERR(fpga->enable_gpio);
> +
> +	fpga->clear_gpio = devm_gpiod_get(fpga->dev, "clear", GPIOD_OUT_LOW);
> +	if (IS_ERR(fpga->clear_gpio))
> +		return PTR_ERR(fpga->clear_gpio);
> +
> +	fpga->strobe_gpio = devm_gpiod_get(fpga->dev, "strobe", GPIOD_OUT_LOW);
> +	if (IS_ERR(fpga->strobe_gpio))
> +		return PTR_ERR(fpga->strobe_gpio);
> +
> +	fpga->datain_gpio = devm_gpiod_get(fpga->dev, "datain", GPIOD_OUT_LOW);
> +	if (IS_ERR(fpga->datain_gpio))
> +		return PTR_ERR(fpga->datain_gpio);
> +
> +	fpga->dataout_gpio = devm_gpiod_get(fpga->dev, "dataout", GPIOD_IN);
> +	if (IS_ERR(fpga->dataout_gpio))
> +		return PTR_ERR(fpga->dataout_gpio);
> +
> +	/*
> +	 * The SoC pinctrl driver may not support reserving the GPIO line for
> +	 * FPGA reset without causing an undesired reset pulse. This will clear
> +	 * any settings on the FPGA, so only do it if we must.
> +	 */
> +	if (fpga->uninitialised) {
> +		fpga->reset_gpio = devm_gpiod_get(fpga->dev, "reset",
> +						  GPIOD_OUT_LOW);

This should be on one line.

> +		if (IS_ERR(fpga->reset_gpio))
> +			return PTR_ERR(fpga->reset_gpio);
> +
> +		gpiod_set_value(fpga->reset_gpio, 1);

Isn't it this line that sends the pulse?

Does GPIOD really send spurious pulses?

> +	}
> +
> +	gpiod_set_value(fpga->enable_gpio, 1);
> +	fpga->uninitialised = false;
> +
> +	return 0;
> +}
> +
> +static int __init upboard_fpga_detect_firmware(struct upboard_fpga *fpga)

I'd half expect this kind of thing to be in drivers/fpga.

Was that considered?

> +{
> +	unsigned int platform_id, manufacturer_id;
> +	unsigned int firmware_id, build, major, minor, patch;
> +	int ret;
> +
> +	if (!fpga)
> +		return -ENOMEM;
> +
> +	ret = regmap_read(fpga->regmap, UPFPGA_REG_PLATFORM_ID, &platform_id);
> +	if (ret)
> +		return ret;
> +
> +	manufacturer_id = platform_id & MENUFACTURER_ID_MASK;
> +	if (manufacturer_id != AAEON_MANUFACTURER_ID) {
> +		dev_err(fpga->dev,
> +			"driver not compatible with custom FPGA FW from manufacturer id 0x%02x. Exiting",
> +			manufacturer_id);
> +		return -ENODEV;
> +	}
> +
> +	ret = regmap_read(fpga->regmap, UPFPGA_REG_FIRMWARE_ID, &firmware_id);
> +	if (ret)
> +		return ret;
> +
> +	build = (firmware_id >> FIRMWARE_ID_BUILD_OFFSET) & FIRMWARE_ID_MASK;
> +	major = (firmware_id >> FIRMWARE_ID_MAJOR_OFFSET) & FIRMWARE_ID_MASK;
> +	minor = (firmware_id >> FIRMWARE_ID_MINOR_OFFSET) & FIRMWARE_ID_MASK;
> +	patch = (firmware_id >> FIRMWARE_ID_PATCH_OFFSET) & FIRMWARE_ID_MASK;
> +
> +	if (major != SUPPORTED_FW_MAJOR) {
> +		dev_dbg(fpga->dev, "unsupported FPGA FW v%u.%u.%u build 0x%02x",
> +			major, minor, patch, build);
> +
> +		return -ENODEV;
> +	}
> +
> +	dev_info(fpga->dev, "compatible FPGA FW v%u.%u.%u build 0x%02x",
> +		 major, minor, patch, build);
> +
> +	return 0;
> +}
> +
> +static void upboard_led_gpio_init(struct upboard_fpga *fpga)

Should this all live in drivers/led?

> +{
> +	struct gpio_led blue_led, yellow_led, green_led, red_led;
> +	struct gpio_desc *desc;
> +	int blue_gpio = -1, yellow_gpio = -1, green_gpio = -1, red_gpio = -1;
> +	int leds = 0;
> +	static struct gpio_led upboard_gpio_leds[8];
> +	static struct gpio_led_platform_data upboard_gpio_led_platform_data;
> +	static const struct mfd_cell upboard_gpio_led_cells[] = {
> +		MFD_CELL_BASIC("leds-gpio", NULL,
> +			       &upboard_gpio_led_platform_data,
> +			       sizeof(upboard_gpio_led_platform_data), 0)
> +	};
> +
> +	desc = devm_gpiod_get(fpga->dev, "blue", GPIOD_OUT_LOW);
> +
> +	if (!IS_ERR(desc)) {
> +		blue_gpio = desc_to_gpio(desc);
> +		leds++;
> +		devm_gpiod_put(fpga->dev, desc);
> +	}
> +	desc = devm_gpiod_get(fpga->dev, "yellow", GPIOD_OUT_LOW);
> +	if (!IS_ERR(desc)) {
> +		yellow_gpio = desc_to_gpio(desc);
> +		leds++;
> +		devm_gpiod_put(fpga->dev, desc);
> +	}
> +	desc = devm_gpiod_get(fpga->dev, "green", GPIOD_OUT_LOW);
> +	if (!IS_ERR(desc)) {
> +		green_gpio = desc_to_gpio(desc);
> +		leds++;
> +		devm_gpiod_put(fpga->dev, desc);
> +	}
> +	desc = devm_gpiod_get(fpga->dev, "red", GPIOD_OUT_LOW);
> +	if (!IS_ERR(desc)) {
> +		red_gpio = desc_to_gpio(desc);
> +		leds++;
> +		devm_gpiod_put(fpga->dev, desc);
> +	}
> +
> +	if (leds == 0)	//no leds
> +		return;
> +
> +	leds = 0;
> +	if (blue_gpio > -1) {
> +		blue_led.name = "upboard:blue:";
> +		blue_led.gpio = blue_gpio;
> +		blue_led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
> +		upboard_gpio_leds[leds++] = blue_led;
> +	}
> +	if (yellow_gpio > -1) {
> +		yellow_led.name = "upboard:yellow:";
> +		yellow_led.gpio = yellow_gpio;
> +		yellow_led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
> +		upboard_gpio_leds[leds++] = yellow_led;
> +	}
> +	if (green_gpio > -1) {
> +		green_led.name = "upboard:green:";
> +		green_led.gpio = green_gpio;
> +		green_led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
> +		upboard_gpio_leds[leds++] = green_led;
> +	}
> +	if (red_gpio > -1) {
> +		red_led.name = "upboard:red:";
> +		red_led.gpio = red_gpio;
> +		red_led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
> +		upboard_gpio_leds[leds++] = red_led;
> +	}
> +
> +	upboard_gpio_led_platform_data.num_leds = leds;
> +	upboard_gpio_led_platform_data.leds = upboard_gpio_leds;
> +
> +	if (devm_mfd_add_devices(fpga->dev, UPBOARD_DEVID,
> +				 upboard_gpio_led_cells,
> +				 ARRAY_SIZE(upboard_gpio_led_cells),
> +				 NULL, 0, NULL)) {
> +		dev_info(fpga->dev, "Failed to add GPIO leds");
> +	}
> +}
> +
> +static const struct acpi_device_id upboard_fpga_acpi_match[] = {
> +	{ "AANT0000", (kernel_ulong_t)&upboard_pinctrl_data },
> +	{ "AANT0F00", (kernel_ulong_t)&upboard_up_fpga_data },
> +	{ "AANT0F01", (kernel_ulong_t)&upboard_up2_fpga_data },
> +	{ "AANT0F02", (kernel_ulong_t)&upboard_upcore_crex_fpga_data },
> +	{ "AANT0F03", (kernel_ulong_t)&upboard_upcore_crst02_fpga_data },
> +	{ "AANT0F04", (kernel_ulong_t)&upboard_up_fpga_data },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(acpi, upboard_fpga_acpi_match);

Please don't push MFD configuration data through the ACPI API.

> +static const struct dmi_system_id upboard_dmi_table[] __initconst = {
> +	{
> +		.matches = { /* UP */
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UP-CHT01"),
> +			DMI_EXACT_MATCH(DMI_BOARD_VERSION, "V0.4"),
> +		},
> +		.driver_data = (void *)UPFPGA_QUIRK_UNINITIALISED,
> +	},
> +	{
> +		.matches = { /* UP2 */
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UP-APL01"),
> +			DMI_EXACT_MATCH(DMI_BOARD_VERSION, "V0.3"),
> +		},
> +		.driver_data = (void *)(UPFPGA_QUIRK_UNINITIALISED |
> +			UPFPGA_QUIRK_HRV1_IS_PROTO2),
> +	},
> +	{
> +		.matches = { /* UP2 Pro*/
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UPN-APL01"),
> +			DMI_EXACT_MATCH(DMI_BOARD_VERSION, "V1.0"),
> +		},
> +		.driver_data = (void *)UPFPGA_QUIRK_HRV1_IS_PROTO2,
> +	},
> +	{
> +		.matches = { /* UP2 */
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UP-APL01"),
> +			DMI_EXACT_MATCH(DMI_BOARD_VERSION, "V0.4"),
> +		},
> +		.driver_data = (void *)UPFPGA_QUIRK_HRV1_IS_PROTO2,
> +	},
> +	{
> +		.matches = { /* UP APL03 */
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UP-APL03"),
> +			DMI_EXACT_MATCH(DMI_BOARD_VERSION, "V1.0"),
> +		},
> +		.driver_data = (void *)(UPFPGA_QUIRK_HRV1_IS_PROTO2 |
> +			UPFPGA_QUIRK_GPIO_LED),
> +	},
> +	{
> +		.matches = { /* UP Xtreme */
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UP-WHL01"),
> +			DMI_EXACT_MATCH(DMI_BOARD_VERSION, "V0.1"),
> +		},
> +	},
> +	{
> +		.matches = { /* UP Xtreme i11 */
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UPX-TGL01"),
> +		},
> +	},
> +	{
> +		.matches = { /* UP Xtreme i12 */
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UPX-ADLP01"),
> +		},
> +	},
> +	{
> +		.matches = { /* UP Squared 6000*/
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UPN-EHL01"),
> +		},
> +	},
> +	{
> +		.matches = { /* UPS 6000 */
> +			DMI_EXACT_MATCH(DMI_SYS_VENDOR, "AAEON"),
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, "UPS-EHL01"),
> +		},
> +	},
> +	{ }
> +};
> +
> +static int __init upboard_fpga_probe(struct platform_device *pdev)
> +{
> +	struct upboard_fpga *fpga;
> +	const struct acpi_device_id *id;
> +	const struct upboard_fpga_data *fpga_data;
> +	const struct dmi_system_id *system_id;
> +	acpi_handle handle;
> +	acpi_status status;
> +	unsigned long long hrv;
> +	unsigned long quirks = 0;
> +	int ret;
> +
> +	id = acpi_match_device(upboard_fpga_acpi_match, &pdev->dev);
> +	if (!id)
> +		return -ENODEV;
> +
> +	handle = ACPI_HANDLE(&pdev->dev);
> +	status = acpi_evaluate_integer(handle, "_HRV", NULL, &hrv);
> +	if (ACPI_FAILURE(status)) {
> +		dev_err(&pdev->dev, "failed to get PCTL revision");
> +		//return -ENODEV;

???

> +	}
> +
> +	system_id = dmi_first_match(upboard_dmi_table);
> +	if (system_id)
> +		quirks = (unsigned long)system_id->driver_data;
> +
> +	if (hrv == UPFPGA_PROTOCOL_V1_HRV &&
> +	    (quirks & UPFPGA_QUIRK_HRV1_IS_PROTO2))
> +		hrv = UPFPGA_PROTOCOL_V2_HRV;
> +
> +	if (hrv != UPFPGA_PROTOCOL_V2_HRV) {
> +		dev_info(&pdev->dev, "unsupported PCTL revision: %llu", hrv);
> +		//return -ENODEV;
> +	}
> +
> +	fpga_data = (const struct upboard_fpga_data *) id->driver_data;
> +
> +	fpga = devm_kzalloc(&pdev->dev, sizeof(*fpga), GFP_KERNEL);
> +	if (!fpga)
> +		return -ENOMEM;
> +
> +	if (quirks & UPFPGA_QUIRK_UNINITIALISED) {
> +		dev_info(&pdev->dev, "FPGA not initialised by this BIOS");
> +		fpga->uninitialised = true;
> +	}
> +
> +	dev_set_drvdata(&pdev->dev, fpga);
> +	fpga->dev = &pdev->dev;
> +	fpga->regmap = devm_regmap_init(&pdev->dev, NULL,
> +					fpga, fpga_data->regmapconf);
> +	fpga->regmapconf = fpga_data->regmapconf;
> +
> +	if (IS_ERR(fpga->regmap))
> +		return PTR_ERR(fpga->regmap);
> +
> +	ret = upboard_fpga_gpio_init(fpga);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +			"failed to initialize FPGA common GPIOs: %d", ret);
> +		//return ret;	//ignore fpga error
> +	} else {
> +		ret = upboard_fpga_detect_firmware(fpga);
> +		//if (ret)
> +		//	return ret;	//ignore fpga error

I'm going to stop here.

Has this been through any internal review at all?

> +	}
> +
> +	//gpio leds initialize
> +	upboard_led_gpio_init(fpga);
> +
> +	if (quirks & UPFPGA_QUIRK_GPIO_LED) {
> +		ret =  devm_mfd_add_devices(&pdev->dev, UPBOARD_DEVID,
> +					    upboard_gpio_led_cells,
> +					    ARRAY_SIZE(upboard_gpio_led_cells),
> +					    NULL, 0, NULL);
> +		if (ret) {
> +			dev_err(&pdev->dev, "Failed to add GPIO leds");
> +			return ret;
> +		}
> +	}
> +	return devm_mfd_add_devices(&pdev->dev, UPBOARD_DEVID,
> +				    fpga_data->cells,
> +				    fpga_data->ncells,
> +				    NULL, 0, NULL);
> +}
> +
> +static struct platform_driver upboard_fpga_driver = {
> +	.driver = {
> +		.name = "upboard-fpga",
> +		.acpi_match_table = upboard_fpga_acpi_match,
> +	},
> +};
> +module_platform_driver_probe(upboard_fpga_driver, upboard_fpga_probe);
> +
> +MODULE_AUTHOR("Gary Wang <garywang@aaeon.com.tw>");
> +MODULE_AUTHOR("Javier Arteaga <javier@emutex.com>");
> +MODULE_DESCRIPTION("UP Board FPGA driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/mfd/upboard-fpga.h b/include/linux/mfd/upboard-fpga.h
> new file mode 100644
> index 000000000000..48273420b97d
> --- /dev/null
> +++ b/include/linux/mfd/upboard-fpga.h
> @@ -0,0 +1,56 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * UP Board main platform driver and FPGA configuration support
> + *
> + * Copyright (c) 2022, Emutex Ltd. All rights reserved.
> + *
> + * Author: Javier Arteaga <javier@emutex.com>
> + */
> +
> +#ifndef __LINUX_MFD_UPBOARD_FPGA_H
> +#define __LINUX_MFD_UPBOARD_FPGA_H
> +
> +//fpga/EC protocol version
> +#define UPFPGA_PROTOCOL_V1_HRV 1
> +#define UPFPGA_PROTOCOL_V2_HRV 2
> +
> +#define UPFPGA_ADDRESS_SIZE  7
> +#define UPFPGA_REGISTER_SIZE 16
> +
> +#define UPFPGA_READ_FLAG     (1 << UPFPGA_ADDRESS_SIZE)
> +
> +enum upboard_fpgareg {
> +	UPFPGA_REG_PLATFORM_ID   = 0x10,
> +	UPFPGA_REG_FIRMWARE_ID   = 0x11,
> +	UPFPGA_REG_FUNC_EN0      = 0x20,
> +	UPFPGA_REG_FUNC_EN1      = 0x21,
> +	UPFPGA_REG_GPIO_EN0      = 0x30,
> +	UPFPGA_REG_GPIO_EN1      = 0x31,
> +	UPFPGA_REG_GPIO_EN2      = 0x32,
> +	UPFPGA_REG_GPIO_DIR0     = 0x40,
> +	UPFPGA_REG_GPIO_DIR1     = 0x41,
> +	UPFPGA_REG_GPIO_DIR2     = 0x42,
> +	UPFPGA_REG_MAX,
> +};
> +
> +struct upboard_fpga {
> +	struct device *dev;
> +	struct regmap *regmap;
> +	const struct regmap_config *regmapconf;
> +	struct gpio_desc *enable_gpio;
> +	struct gpio_desc *reset_gpio;
> +	struct gpio_desc *clear_gpio;
> +	struct gpio_desc *strobe_gpio;
> +	struct gpio_desc *datain_gpio;
> +	struct gpio_desc *dataout_gpio;
> +	bool uninitialised;
> +};
> +
> +struct upboard_led_data {
> +	unsigned int bit;
> +	const char *colour;
> +};
> +
> +bool regmap_check_writeable(struct upboard_fpga *fpga, unsigned int reg);
> +
> +#endif /*  __LINUX_MFD_UPBOARD_FPGA_H */