mfd: Add support for AAEON UP board FPGA

The UP boards implement some features (pin controller, LEDs) through an
on-board FPGA.

This MFD driver implements the line protocol to communicate with the FPGA
through regmap, and registers pin controller and led cells.

This commit adds support for UP and UP Squared boards.

Based on the work done by Gary Wang <garywang@aaeon.com.tw>.

Signed-off-by: Thomas Richard <thomas.richard@bootlin.com>
Link: https://lore.kernel.org/r/20241211-aaeon-up-board-pinctrl-support-v1-1-24719be27631@bootlin.com
Signed-off-by: Lee Jones <lee@kernel.org>

drivers/mfd/Kconfig

@@ -2427,5 +2427,17 @@ config MFD_RSMU_SPI
 	  Additional drivers must be enabled in order to use the functionality
 	  of the device.
 
+config MFD_UPBOARD_FPGA
+	tristate "Support for the AAeon UP board FPGA"
+	depends on (X86 && ACPI)
+	select MFD_CORE
+	help
+	  Select this option to enable the AAEON UP and UP^2 onboard FPGA.
+	  This is the core driver of this FPGA, which has a pin controller and a
+	  LED controller.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called upboard-fpga.
+
 endmenu
 endif

drivers/mfd/Makefile

@@ -292,3 +292,5 @@ obj-$(CONFIG_MFD_QNAP_MCU)	+= qnap-mcu.o
 
 obj-$(CONFIG_MFD_RSMU_I2C)	+= rsmu_i2c.o rsmu_core.o
 obj-$(CONFIG_MFD_RSMU_SPI)	+= rsmu_spi.o rsmu_core.o
+
+obj-$(CONFIG_MFD_UPBOARD_FPGA)	+= upboard-fpga.o

drivers/mfd/upboard-fpga.c

@@ -0,0 +1,325 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * UP Board FPGA driver.
+ *
+ * FPGA provides more GPIO driving power, LEDS and pin mux function.
+ *
+ * Copyright (c) AAEON. All rights reserved.
+ * Copyright (C) 2024 Bootlin
+ *
+ * Author: Gary Wang <garywang@aaeon.com.tw>
+ * Author: Thomas Richard <thomas.richard@bootlin.com>
+ */
+
+#include <linux/acpi.h>
+#include <linux/bitfield.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio/consumer.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/upboard-fpga.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/sysfs.h>
+
+#define UPBOARD_AAEON_MANUFACTURER_ID	0x01
+#define UPBOARD_MANUFACTURER_ID_MASK	GENMASK(7, 0)
+
+#define UPBOARD_ADDRESS_SIZE  7
+#define UPBOARD_REGISTER_SIZE 16
+
+#define UPBOARD_READ_FLAG     BIT(UPBOARD_ADDRESS_SIZE)
+
+#define UPBOARD_FW_ID_MAJOR_SUPPORTED	0x0
+
+#define UPBOARD_FW_ID_BUILD_MASK	GENMASK(15, 12)
+#define UPBOARD_FW_ID_MAJOR_MASK	GENMASK(11, 8)
+#define UPBOARD_FW_ID_MINOR_MASK	GENMASK(7, 4)
+#define UPBOARD_FW_ID_PATCH_MASK	GENMASK(3, 0)
+
+static int upboard_fpga_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct upboard_fpga *fpga = context;
+	int i;
+
+	/* Clear to start new transaction */
+	gpiod_set_value(fpga->clear_gpio, 0);
+	gpiod_set_value(fpga->clear_gpio, 1);
+
+	reg |= UPBOARD_READ_FLAG;
+
+	/* Send clock and addr from strobe & datain pins */
+	for (i = UPBOARD_ADDRESS_SIZE; i >= 0; i--) {
+		gpiod_set_value(fpga->strobe_gpio, 0);
+		gpiod_set_value(fpga->datain_gpio, !!(reg & BIT(i)));
+		gpiod_set_value(fpga->strobe_gpio, 1);
+	}
+
+	gpiod_set_value(fpga->strobe_gpio, 0);
+	*val = 0;
+
+	/* Read data from dataout pin */
+	for (i = UPBOARD_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 *fpga = context;
+	int i;
+
+	/* Clear to start new transcation */
+	gpiod_set_value(fpga->clear_gpio, 0);
+	gpiod_set_value(fpga->clear_gpio, 1);
+
+	/* Send clock and addr from strobe & datain pins */
+	for (i = UPBOARD_ADDRESS_SIZE; i >= 0; i--) {
+		gpiod_set_value(fpga->strobe_gpio, 0);
+		gpiod_set_value(fpga->datain_gpio, !!(reg & BIT(i)));
+		gpiod_set_value(fpga->strobe_gpio, 1);
+	}
+
+	gpiod_set_value(fpga->strobe_gpio, 0);
+
+	/* Write data to datain pin */
+	for (i = UPBOARD_REGISTER_SIZE - 1; i >= 0; i--) {
+		gpiod_set_value(fpga->datain_gpio, !!(val & BIT(i)));
+		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(UPBOARD_REG_PLATFORM_ID, UPBOARD_REG_FIRMWARE_ID),
+	regmap_reg_range(UPBOARD_REG_FUNC_EN0, UPBOARD_REG_FUNC_EN0),
+	regmap_reg_range(UPBOARD_REG_GPIO_EN0, UPBOARD_REG_GPIO_EN1),
+	regmap_reg_range(UPBOARD_REG_GPIO_DIR0, UPBOARD_REG_GPIO_DIR1),
+};
+
+static const struct regmap_range upboard_up_writable_ranges[] = {
+	regmap_reg_range(UPBOARD_REG_FUNC_EN0, UPBOARD_REG_FUNC_EN0),
+	regmap_reg_range(UPBOARD_REG_GPIO_EN0, UPBOARD_REG_GPIO_EN1),
+	regmap_reg_range(UPBOARD_REG_GPIO_DIR0, UPBOARD_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 = UPBOARD_ADDRESS_SIZE,
+	.val_bits = UPBOARD_REGISTER_SIZE,
+	.max_register = UPBOARD_REG_MAX,
+	.reg_read = upboard_fpga_read,
+	.reg_write = upboard_fpga_write,
+	.fast_io = false,
+	.cache_type = REGCACHE_NONE,
+	.rd_table = &upboard_up_readable_table,
+	.wr_table = &upboard_up_writable_table,
+};
+
+static const struct regmap_range upboard_up2_readable_ranges[] = {
+	regmap_reg_range(UPBOARD_REG_PLATFORM_ID, UPBOARD_REG_FIRMWARE_ID),
+	regmap_reg_range(UPBOARD_REG_FUNC_EN0, UPBOARD_REG_FUNC_EN1),
+	regmap_reg_range(UPBOARD_REG_GPIO_EN0, UPBOARD_REG_GPIO_EN2),
+	regmap_reg_range(UPBOARD_REG_GPIO_DIR0, UPBOARD_REG_GPIO_DIR2),
+};
+
+static const struct regmap_range upboard_up2_writable_ranges[] = {
+	regmap_reg_range(UPBOARD_REG_FUNC_EN0, UPBOARD_REG_FUNC_EN1),
+	regmap_reg_range(UPBOARD_REG_GPIO_EN0, UPBOARD_REG_GPIO_EN2),
+	regmap_reg_range(UPBOARD_REG_GPIO_DIR0, UPBOARD_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 = UPBOARD_ADDRESS_SIZE,
+	.val_bits = UPBOARD_REGISTER_SIZE,
+	.max_register = UPBOARD_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 const struct mfd_cell upboard_up_mfd_cells[] = {
+	{ .name = "upboard-pinctrl" },
+	{ .name = "upboard-leds" },
+};
+
+static const struct upboard_fpga_data upboard_up_fpga_data = {
+	.type = UPBOARD_UP_FPGA,
+	.regmap_config = &upboard_up_regmap_config,
+};
+
+static const struct upboard_fpga_data upboard_up2_fpga_data = {
+	.type = UPBOARD_UP2_FPGA,
+	.regmap_config = &upboard_up2_regmap_config,
+};
+
+static int upboard_fpga_gpio_init(struct upboard_fpga *fpga)
+{
+	fpga->enable_gpio = devm_gpiod_get(fpga->dev, "enable", GPIOD_ASIS);
+	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);
+
+	gpiod_set_value(fpga->enable_gpio, 1);
+
+	return 0;
+}
+
+static int upboard_fpga_get_firmware_version(struct upboard_fpga *fpga)
+{
+	unsigned int platform_id, manufacturer_id;
+	int ret;
+
+	if (!fpga)
+		return -ENOMEM;
+
+	ret = regmap_read(fpga->regmap, UPBOARD_REG_PLATFORM_ID, &platform_id);
+	if (ret)
+		return ret;
+
+	manufacturer_id = platform_id & UPBOARD_MANUFACTURER_ID_MASK;
+	if (manufacturer_id != UPBOARD_AAEON_MANUFACTURER_ID)
+		return dev_err_probe(fpga->dev, -ENODEV,
+				     "driver not compatible with custom FPGA FW from manufacturer id %#02x.",
+				     manufacturer_id);
+
+	ret = regmap_read(fpga->regmap, UPBOARD_REG_FIRMWARE_ID, &fpga->firmware_version);
+	if (ret)
+		return ret;
+
+	if (FIELD_GET(UPBOARD_FW_ID_MAJOR_MASK, fpga->firmware_version) !=
+	    UPBOARD_FW_ID_MAJOR_SUPPORTED)
+		return dev_err_probe(fpga->dev, -ENODEV,
+				     "unsupported FPGA FW v%lu.%lu.%lu build %#02lx",
+				     FIELD_GET(UPBOARD_FW_ID_MAJOR_MASK, fpga->firmware_version),
+				     FIELD_GET(UPBOARD_FW_ID_MINOR_MASK, fpga->firmware_version),
+				     FIELD_GET(UPBOARD_FW_ID_PATCH_MASK, fpga->firmware_version),
+				     FIELD_GET(UPBOARD_FW_ID_BUILD_MASK, fpga->firmware_version));
+	return 0;
+}
+
+static ssize_t upboard_fpga_version_show(struct device *dev, struct device_attribute *attr,
+					 char *buf)
+{
+	struct upboard_fpga *fpga = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "FPGA FW v%lu.%lu.%lu build %#02lx\n",
+			  FIELD_GET(UPBOARD_FW_ID_MAJOR_MASK, fpga->firmware_version),
+			  FIELD_GET(UPBOARD_FW_ID_MINOR_MASK, fpga->firmware_version),
+			  FIELD_GET(UPBOARD_FW_ID_PATCH_MASK, fpga->firmware_version),
+			  FIELD_GET(UPBOARD_FW_ID_BUILD_MASK, fpga->firmware_version));
+}
+
+static DEVICE_ATTR_RO(upboard_fpga_version);
+
+static struct attribute *upboard_fpga_attrs[] = {
+	&dev_attr_upboard_fpga_version.attr,
+	NULL
+};
+
+ATTRIBUTE_GROUPS(upboard_fpga);
+
+static int upboard_fpga_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct upboard_fpga *fpga;
+	int ret;
+
+	fpga = devm_kzalloc(dev, sizeof(*fpga), GFP_KERNEL);
+	if (!fpga)
+		return -ENOMEM;
+
+	fpga->fpga_data = device_get_match_data(dev);
+
+	fpga->dev = dev;
+
+	platform_set_drvdata(pdev, fpga);
+
+	fpga->regmap = devm_regmap_init(dev, NULL, fpga, fpga->fpga_data->regmap_config);
+	if (IS_ERR(fpga->regmap))
+		return PTR_ERR(fpga->regmap);
+
+	ret = upboard_fpga_gpio_init(fpga);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to initialize FPGA common GPIOs");
+
+	ret = upboard_fpga_get_firmware_version(fpga);
+	if (ret)
+		return ret;
+
+	return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE, upboard_up_mfd_cells,
+				    ARRAY_SIZE(upboard_up_mfd_cells), NULL, 0, NULL);
+}
+
+static const struct acpi_device_id upboard_fpga_acpi_match[] = {
+	{ "AANT0F01", (kernel_ulong_t)&upboard_up2_fpga_data },
+	{ "AANT0F04", (kernel_ulong_t)&upboard_up_fpga_data },
+	{}
+};
+MODULE_DEVICE_TABLE(acpi, upboard_fpga_acpi_match);
+
+static struct platform_driver upboard_fpga_driver = {
+	.driver = {
+		.name = "upboard-fpga",
+		.acpi_match_table = ACPI_PTR(upboard_fpga_acpi_match),
+		.dev_groups	= upboard_fpga_groups,
+	},
+	.probe = upboard_fpga_probe,
+};
+
+module_platform_driver(upboard_fpga_driver);
+
+MODULE_AUTHOR("Gary Wang <garywang@aaeon.com.tw>");
+MODULE_AUTHOR("Thomas Richard <thomas.richard@bootlin.com>");
+MODULE_DESCRIPTION("UP Board FPGA driver");
+MODULE_LICENSE("GPL");