usb: typec: ucsi: Add support for Flipper One MCU UCSI controller

Flipper One is a handheld multi-tool device with an integrated MCU that
exposes USB Type-C controller functionality among other things, following
the UCSI specification. Add a driver for it.

Signed-off-by: Alexey Charkov <alchark@flipper.net>

Author: alchark

drivers/usb/typec/ucsi/Kconfig

@@ -104,4 +104,15 @@ config UCSI_HUAWEI_GAOKUN
 	  To compile the driver as a module, choose M here: the module will be
 	  called ucsi_huawei_gaokun.
 
+config UCSI_FLIPPER_ONE
+	tristate "UCSI Interface Driver for Flipper One MCU"
+	depends on MFD_FLIPPER_ONE
+	help
+	  This driver enables UCSI support for the Type-C controller exposed
+	  by the Flipper One MCU, which presents the UCSI data structure as a
+	  register block in the shared MCU I2C register map.
+
+	  To compile the driver as a module, choose M here: the module will be
+	  called ucsi_flipper_one.
+
 endif

drivers/usb/typec/ucsi/Makefile

@@ -28,3 +28,4 @@ obj-$(CONFIG_UCSI_PMIC_GLINK)		+= ucsi_glink.o
 obj-$(CONFIG_CROS_EC_UCSI)		+= cros_ec_ucsi.o
 obj-$(CONFIG_UCSI_LENOVO_YOGA_C630)	+= ucsi_yoga_c630.o
 obj-$(CONFIG_UCSI_HUAWEI_GAOKUN)	+= ucsi_huawei_gaokun.o
+obj-$(CONFIG_UCSI_FLIPPER_ONE)		+= ucsi_flipper_one.o

drivers/usb/typec/ucsi/ucsi_flipper_one.c

@@ -0,0 +1,175 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UCSI driver for the Flipper One MCU Type-C controller
+ * Copyright (C) 2026 Flipper FZCO
+ */
+
+#include <linux/interrupt.h>
+#include <linux/mfd/flipper-one-mcu.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/unaligned.h>
+
+#include "ucsi.h"
+
+struct flipper_one_ucsi {
+	struct device *dev;
+	struct regmap *regmap;
+	struct ucsi *ucsi;
+	int irq;
+};
+
+/*
+ * Read @len bytes from the UCSI register at MCU address @reg.
+ *
+ * regmap_raw_read() only accepts lengths that are a multiple of the register
+ * width, but UCSI messages can have odd lengths, so round @len up into a bounce
+ * buffer (the largest possible read is one message window)
+ */
+static int flipper_one_ucsi_read(struct ucsi *ucsi, unsigned int reg,
+				 void *val, size_t len)
+{
+	struct flipper_one_ucsi *fo = ucsi_get_drvdata(ucsi);
+	u8 buf[FOMCU_UCSI_MESSAGE_LEN];
+	size_t aligned = round_up(len, regmap_get_val_bytes(fo->regmap));
+	int ret;
+
+	if (aligned > sizeof(buf))
+		return -EINVAL;
+
+	ret = regmap_raw_read(fo->regmap, reg, buf, aligned);
+	if (ret)
+		return ret;
+
+	memcpy(val, buf, len);
+	return 0;
+}
+
+static int flipper_one_ucsi_read_version(struct ucsi *ucsi, u16 *version)
+{
+	return flipper_one_ucsi_read(ucsi, FOMCU_REG_UCSI_VERSION, version,
+				     sizeof(*version));
+}
+
+static int flipper_one_ucsi_read_cci(struct ucsi *ucsi, u32 *cci)
+{
+	return flipper_one_ucsi_read(ucsi, FOMCU_REG_UCSI_CCI, cci,
+				     sizeof(*cci));
+}
+
+static int flipper_one_ucsi_read_message_in(struct ucsi *ucsi, void *val,
+					    size_t len)
+{
+	return flipper_one_ucsi_read(ucsi, FOMCU_REG_UCSI_MESSAGE_IN, val, len);
+}
+
+static int flipper_one_ucsi_async_control(struct ucsi *ucsi, u64 command)
+{
+	struct flipper_one_ucsi *fo = ucsi_get_drvdata(ucsi);
+
+	return regmap_raw_write(fo->regmap, FOMCU_REG_UCSI_CONTROL,
+				&command, sizeof(command));
+}
+
+static const struct ucsi_operations flipper_one_ucsi_ops = {
+	.read_version = flipper_one_ucsi_read_version,
+	.read_cci = flipper_one_ucsi_read_cci,
+	.poll_cci = flipper_one_ucsi_read_cci,
+	.read_message_in = flipper_one_ucsi_read_message_in,
+	.sync_control = ucsi_sync_control_common,
+	.async_control = flipper_one_ucsi_async_control,
+};
+
+static irqreturn_t flipper_one_ucsi_irq(int irq, void *data)
+{
+	struct flipper_one_ucsi *fo = data;
+	u32 cci;
+	int ret;
+
+	ret = flipper_one_ucsi_read_cci(fo->ucsi, &cci);
+	if (ret)
+		return IRQ_NONE;
+
+	ucsi_notify_common(fo->ucsi, cci);
+
+	return IRQ_HANDLED;
+}
+
+static int flipper_one_ucsi_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct flipper_one_ucsi *fo;
+	int ret;
+
+	fo = devm_kzalloc(dev, sizeof(*fo), GFP_KERNEL);
+	if (!fo)
+		return -ENOMEM;
+
+	fo->dev = dev;
+
+	fo->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!fo->regmap)
+		return dev_err_probe(dev, -ENODEV, "Failed to get MCU regmap\n");
+
+	fo->irq = platform_get_irq(pdev, 0);
+	if (fo->irq < 0)
+		return fo->irq;
+
+	fo->ucsi = ucsi_create(dev, &flipper_one_ucsi_ops);
+	if (IS_ERR(fo->ucsi))
+		return PTR_ERR(fo->ucsi);
+
+	ucsi_set_drvdata(fo->ucsi, fo);
+	platform_set_drvdata(pdev, fo);
+
+	ret = request_threaded_irq(fo->irq, NULL, flipper_one_ucsi_irq,
+				   IRQF_ONESHOT, dev_name(dev), fo);
+	if (ret) {
+		dev_err_probe(dev, ret, "Failed to request IRQ\n");
+		goto err_destroy;
+	}
+
+	ret = ucsi_register(fo->ucsi);
+	if (ret) {
+		dev_err_probe(dev, ret, "Failed to register UCSI\n");
+		goto err_free_irq;
+	}
+
+	return 0;
+
+err_free_irq:
+	free_irq(fo->irq, fo);
+err_destroy:
+	ucsi_destroy(fo->ucsi);
+	return ret;
+}
+
+static void flipper_one_ucsi_remove(struct platform_device *pdev)
+{
+	struct flipper_one_ucsi *fo = platform_get_drvdata(pdev);
+
+	ucsi_unregister(fo->ucsi);
+	free_irq(fo->irq, fo);
+	ucsi_destroy(fo->ucsi);
+}
+
+static const struct platform_device_id flipper_one_ucsi_ids[] = {
+	{ "flipper-one-typec" },
+	{}
+};
+MODULE_DEVICE_TABLE(platform, flipper_one_ucsi_ids);
+
+static struct platform_driver flipper_one_ucsi_driver = {
+	.driver = {
+		.name = "flipper-one-typec",
+	},
+	.probe = flipper_one_ucsi_probe,
+	.remove = flipper_one_ucsi_remove,
+	.id_table = flipper_one_ucsi_ids,
+};
+module_platform_driver(flipper_one_ucsi_driver);
+
+MODULE_DESCRIPTION("UCSI driver for Flipper One MCU Type-C controller");
+MODULE_AUTHOR("Alexey Charkov <alchark@flipper.net>");
+MODULE_LICENSE("GPL");