platform: arm64: add Lenovo Yoga C630 WOS EC driver

Lenovo Yoga C630 WOS is a laptop using Snapdragon 850 SoC. Like many
laptops it uses an embedded controller (EC) to perform various platform
operations, including, but not limited, to Type-C port control or power
supply handlng.

Add the driver for the EC, that creates devices for UCSI and power
supply devices.

Reviewed-by: Bryan O'Donoghue <[e-mail]>
Signed-off-by: Dmitry Baryshkov <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
[ij: added #include <linux/cleanup.h>]
Reviewed-by: Ilpo Järvinen <[e-mail]>
Signed-off-by: Ilpo Järvinen <[e-mail]>

drivers/platform/arm64/Kconfig

···
 	  laptop where this information is not properly exposed via the
 	  standard ACPI devices.
 
+config EC_LENOVO_YOGA_C630
+	tristate "Lenovo Yoga C630 Embedded Controller driver"
+	depends on I2C
+	help
+	  Driver for the Embedded Controller in the Qualcomm Snapdragon-based
+	  Lenovo Yoga C630, which provides battery and power adapter
+	  information.
+
+	  This driver provides battery and AC status support for the mentioned
+	  laptop where this information is not properly exposed via the
+	  standard ACPI devices.
+
+	  Say M or Y here to include this support.
+
 endif # ARM64_PLATFORM_DEVICES

drivers/platform/arm64/Makefile

···
 #
 
 obj-$(CONFIG_EC_ACER_ASPIRE1)	+= acer-aspire1-ec.o
+obj-$(CONFIG_EC_LENOVO_YOGA_C630) += lenovo-yoga-c630.o

drivers/platform/arm64/lenovo-yoga-c630.c

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2024, Linaro Ltd
+ * Authors:
+ *    Bjorn Andersson
+ *    Dmitry Baryshkov
+ */
+#include <linux/auxiliary_bus.h>
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/irqreturn.h>
+#include <linux/lockdep.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/notifier.h>
+#include <linux/slab.h>
+#include <linux/platform_data/lenovo-yoga-c630.h>
+
+#define LENOVO_EC_RESPONSE_REG		0x01
+#define LENOVO_EC_REQUEST_REG		0x02
+
+#define LENOVO_EC_UCSI_WRITE		0x20
+#define LENOVO_EC_UCSI_READ		0x21
+
+#define LENOVO_EC_READ_REG		0xb0
+#define LENOVO_EC_REQUEST_NEXT_EVENT	0x84
+
+#define LENOVO_EC_UCSI_VERSION		0x20
+
+struct yoga_c630_ec {
+	struct i2c_client *client;
+	struct mutex lock;
+	struct blocking_notifier_head notifier_list;
+};
+
+static int yoga_c630_ec_request(struct yoga_c630_ec *ec, u8 *req, size_t req_len,
+				u8 *resp, size_t resp_len)
+{
+	int ret;
+
+	lockdep_assert_held(&ec->lock);
+
+	ret = i2c_smbus_write_i2c_block_data(ec->client, LENOVO_EC_REQUEST_REG,
+					     req_len, req);
+	if (ret < 0)
+		return ret;
+
+	return i2c_smbus_read_i2c_block_data(ec->client, LENOVO_EC_RESPONSE_REG,
+					     resp_len, resp);
+}
+
+int yoga_c630_ec_read8(struct yoga_c630_ec *ec, u8 addr)
+{
+	u8 req[2] = { LENOVO_EC_READ_REG, };
+	int ret;
+	u8 val;
+
+	guard(mutex)(&ec->lock);
+
+	req[1] = addr;
+	ret = yoga_c630_ec_request(ec, req, sizeof(req), &val, 1);
+	if (ret < 0)
+		return ret;
+
+	return val;
+}
+EXPORT_SYMBOL_GPL(yoga_c630_ec_read8);
+
+int yoga_c630_ec_read16(struct yoga_c630_ec *ec, u8 addr)
+{
+	u8 req[2] = { LENOVO_EC_READ_REG, };
+	int ret;
+	u8 msb;
+	u8 lsb;
+
+	/* don't overflow the address */
+	if (addr == 0xff)
+		return -EINVAL;
+
+	guard(mutex)(&ec->lock);
+
+	req[1] = addr;
+	ret = yoga_c630_ec_request(ec, req, sizeof(req), &lsb, 1);
+	if (ret < 0)
+		return ret;
+
+	req[1] = addr + 1;
+	ret = yoga_c630_ec_request(ec, req, sizeof(req), &msb, 1);
+	if (ret < 0)
+		return ret;
+
+	return msb << 8 | lsb;
+}
+EXPORT_SYMBOL_GPL(yoga_c630_ec_read16);
+
+u16 yoga_c630_ec_ucsi_get_version(struct yoga_c630_ec *ec)
+{
+	u8 req[3] = { 0xb3, 0xf2, };
+	int ret;
+	u8 msb;
+	u8 lsb;
+
+	guard(mutex)(&ec->lock);
+
+	req[2] = LENOVO_EC_UCSI_VERSION;
+	ret = yoga_c630_ec_request(ec, req, sizeof(req), &lsb, 1);
+	if (ret < 0)
+		return ret;
+
+	req[2] = LENOVO_EC_UCSI_VERSION + 1;
+	ret = yoga_c630_ec_request(ec, req, sizeof(req), &msb, 1);
+	if (ret < 0)
+		return ret;
+
+	return msb << 8 | lsb;
+}
+EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_get_version);
+
+int yoga_c630_ec_ucsi_write(struct yoga_c630_ec *ec,
+			    const u8 req[YOGA_C630_UCSI_WRITE_SIZE])
+{
+	int ret;
+
+	mutex_lock(&ec->lock);
+	ret = i2c_smbus_write_i2c_block_data(ec->client, LENOVO_EC_UCSI_WRITE,
+					     YOGA_C630_UCSI_WRITE_SIZE, req);
+	mutex_unlock(&ec->lock);
+
+	return ret < 0 ? ret : 0;
+}
+EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_write);
+
+int yoga_c630_ec_ucsi_read(struct yoga_c630_ec *ec,
+			   u8 resp[YOGA_C630_UCSI_READ_SIZE])
+{
+	int ret;
+
+	mutex_lock(&ec->lock);
+	ret = i2c_smbus_read_i2c_block_data(ec->client, LENOVO_EC_UCSI_READ,
+					    YOGA_C630_UCSI_READ_SIZE, resp);
+	mutex_unlock(&ec->lock);
+
+	return ret < 0 ? ret : 0;
+}
+EXPORT_SYMBOL_GPL(yoga_c630_ec_ucsi_read);
+
+static irqreturn_t yoga_c630_ec_thread_intr(int irq, void *data)
+{
+	u8 req[] = { LENOVO_EC_REQUEST_NEXT_EVENT };
+	struct yoga_c630_ec *ec = data;
+	u8 event;
+	int ret;
+
+	mutex_lock(&ec->lock);
+	ret = yoga_c630_ec_request(ec, req, sizeof(req), &event, 1);
+	mutex_unlock(&ec->lock);
+	if (ret < 0)
+		return IRQ_HANDLED;
+
+	blocking_notifier_call_chain(&ec->notifier_list, event, ec);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * yoga_c630_ec_register_notify - Register a notifier callback for EC events.
+ * @ec: Yoga C630 EC
+ * @nb: Notifier block pointer to register
+ *
+ * Return: 0 on success or negative error code.
+ */
+int yoga_c630_ec_register_notify(struct yoga_c630_ec *ec, struct notifier_block *nb)
+{
+	return blocking_notifier_chain_register(&ec->notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(yoga_c630_ec_register_notify);
+
+/**
+ * yoga_c630_ec_unregister_notify - Unregister notifier callback for EC events.
+ * @ec: Yoga C630 EC
+ * @nb: Notifier block pointer to unregister
+ *
+ * Unregister a notifier callback that was previously registered with
+ * yoga_c630_ec_register_notify().
+ */
+void yoga_c630_ec_unregister_notify(struct yoga_c630_ec *ec, struct notifier_block *nb)
+{
+	blocking_notifier_chain_unregister(&ec->notifier_list, nb);
+}
+EXPORT_SYMBOL_GPL(yoga_c630_ec_unregister_notify);
+
+static void yoga_c630_aux_release(struct device *dev)
+{
+	struct auxiliary_device *adev = to_auxiliary_dev(dev);
+
+	kfree(adev);
+}
+
+static void yoga_c630_aux_remove(void *data)
+{
+	struct auxiliary_device *adev = data;
+
+	auxiliary_device_delete(adev);
+	auxiliary_device_uninit(adev);
+}
+
+static int yoga_c630_aux_init(struct device *parent, const char *name,
+			      struct yoga_c630_ec *ec)
+{
+	struct auxiliary_device *adev;
+	int ret;
+
+	adev = kzalloc(sizeof(*adev), GFP_KERNEL);
+	if (!adev)
+		return -ENOMEM;
+
+	adev->name = name;
+	adev->id = 0;
+	adev->dev.parent = parent;
+	adev->dev.release = yoga_c630_aux_release;
+	adev->dev.platform_data = ec;
+
+	ret = auxiliary_device_init(adev);
+	if (ret) {
+		kfree(adev);
+		return ret;
+	}
+
+	ret = auxiliary_device_add(adev);
+	if (ret) {
+		auxiliary_device_uninit(adev);
+		return ret;
+	}
+
+	return devm_add_action_or_reset(parent, yoga_c630_aux_remove, adev);
+}
+
+static int yoga_c630_ec_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct yoga_c630_ec *ec;
+	int ret;
+
+	ec = devm_kzalloc(dev, sizeof(*ec), GFP_KERNEL);
+	if (!ec)
+		return -ENOMEM;
+
+	mutex_init(&ec->lock);
+	ec->client = client;
+	BLOCKING_INIT_NOTIFIER_HEAD(&ec->notifier_list);
+
+	ret = devm_request_threaded_irq(dev, client->irq,
+					NULL, yoga_c630_ec_thread_intr,
+					IRQF_ONESHOT, "yoga_c630_ec", ec);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "unable to request irq\n");
+
+	ret = yoga_c630_aux_init(dev, YOGA_C630_DEV_PSY, ec);
+	if (ret)
+		return ret;
+
+	return yoga_c630_aux_init(dev, YOGA_C630_DEV_UCSI, ec);
+}
+
+
+static const struct of_device_id yoga_c630_ec_of_match[] = {
+	{ .compatible = "lenovo,yoga-c630-ec" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, yoga_c630_ec_of_match);
+
+static const struct i2c_device_id yoga_c630_ec_i2c_id_table[] = {
+	{ "yoga-c630-ec", },
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, yoga_c630_ec_i2c_id_table);
+
+static struct i2c_driver yoga_c630_ec_i2c_driver = {
+	.driver = {
+		.name = "yoga-c630-ec",
+		.of_match_table = yoga_c630_ec_of_match
+	},
+	.probe = yoga_c630_ec_probe,
+	.id_table = yoga_c630_ec_i2c_id_table,
+};
+module_i2c_driver(yoga_c630_ec_i2c_driver);
+
+MODULE_DESCRIPTION("Lenovo Yoga C630 Embedded Controller");
+MODULE_LICENSE("GPL");

include/linux/platform_data/lenovo-yoga-c630.h

···
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2022-2024, Linaro Ltd
+ * Authors:
+ *    Bjorn Andersson
+ *    Dmitry Baryshkov
+ */
+
+#ifndef _LENOVO_YOGA_C630_DATA_H
+#define _LENOVO_YOGA_C630_DATA_H
+
+struct yoga_c630_ec;
+struct notifier_block;
+
+#define YOGA_C630_MOD_NAME	"lenovo_yoga_c630"
+
+#define YOGA_C630_DEV_UCSI	"ucsi"
+#define YOGA_C630_DEV_PSY	"psy"
+
+int yoga_c630_ec_read8(struct yoga_c630_ec *ec, u8 addr);
+int yoga_c630_ec_read16(struct yoga_c630_ec *ec, u8 addr);
+
+int yoga_c630_ec_register_notify(struct yoga_c630_ec *ec, struct notifier_block *nb);
+void yoga_c630_ec_unregister_notify(struct yoga_c630_ec *ec, struct notifier_block *nb);
+
+#define YOGA_C630_UCSI_WRITE_SIZE	8
+#define YOGA_C630_UCSI_CCI_SIZE		4
+#define YOGA_C630_UCSI_DATA_SIZE	16
+#define YOGA_C630_UCSI_READ_SIZE	(YOGA_C630_UCSI_CCI_SIZE + YOGA_C630_UCSI_DATA_SIZE)
+
+u16 yoga_c630_ec_ucsi_get_version(struct yoga_c630_ec *ec);
+int yoga_c630_ec_ucsi_write(struct yoga_c630_ec *ec,
+			    const u8 req[YOGA_C630_UCSI_WRITE_SIZE]);
+int yoga_c630_ec_ucsi_read(struct yoga_c630_ec *ec,
+			   u8 resp[YOGA_C630_UCSI_READ_SIZE]);
+
+#define LENOVO_EC_EVENT_USB		0x20
+#define LENOVO_EC_EVENT_UCSI		0x21
+#define LENOVO_EC_EVENT_HPD		0x22
+#define LENOVO_EC_EVENT_BAT_STATUS	0x24
+#define LENOVO_EC_EVENT_BAT_INFO	0x25
+#define LENOVO_EC_EVENT_BAT_ADPT_STATUS	0x37
+
+#endif