usb: typec: ucsi: add support for Cypress CCGx

Latest NVIDIA GPU cards have a Cypress CCGx Type-C controller
over I2C interface.

This UCSI I2C driver uses I2C bus driver interface for communicating
with Type-C controller.
Signed-off-by: Ajay Gupta <ajayg@nvidia.com>
Acked-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

drivers/usb/typec/ucsi/Kconfig

@@ -23,6 +23,16 @@ config TYPEC_UCSI
 
 if TYPEC_UCSI
 
+config UCSI_CCG
+	tristate "UCSI Interface Driver for Cypress CCGx"
+	depends on I2C
+	help
+	  This driver enables UCSI support on platforms that expose a
+	  Cypress CCGx Type-C controller over I2C interface.
+
+	  To compile the driver as a module, choose M here: the module will be
+	  called ucsi_ccg.
+
 config UCSI_ACPI
 	tristate "UCSI ACPI Interface Driver"
 	depends on ACPI

drivers/usb/typec/ucsi/Makefile

@@ -8,3 +8,5 @@ typec_ucsi-y			:= ucsi.o
 typec_ucsi-$(CONFIG_TRACING)	+= trace.o
 
 obj-$(CONFIG_UCSI_ACPI)		+= ucsi_acpi.o
+
+obj-$(CONFIG_UCSI_CCG)		+= ucsi_ccg.o

drivers/usb/typec/ucsi/ucsi_ccg.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * UCSI driver for Cypress CCGx Type-C controller
+ *
+ * Copyright (C) 2017-2018 NVIDIA Corporation. All rights reserved.
+ * Author: Ajay Gupta <ajayg@nvidia.com>
+ *
+ * Some code borrowed from drivers/usb/typec/ucsi/ucsi_acpi.c
+ */
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+
+#include <asm/unaligned.h>
+#include "ucsi.h"
+
+struct ucsi_ccg {
+	struct device *dev;
+	struct ucsi *ucsi;
+	struct ucsi_ppm ppm;
+	struct i2c_client *client;
+};
+
+#define CCGX_RAB_INTR_REG			0x06
+#define CCGX_RAB_UCSI_CONTROL			0x39
+#define CCGX_RAB_UCSI_CONTROL_START		BIT(0)
+#define CCGX_RAB_UCSI_CONTROL_STOP		BIT(1)
+#define CCGX_RAB_UCSI_DATA_BLOCK(offset)	(0xf000 | ((offset) & 0xff))
+
+static int ccg_read(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
+{
+	struct i2c_client *client = uc->client;
+	const struct i2c_adapter_quirks *quirks = client->adapter->quirks;
+	unsigned char buf[2];
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= client->addr,
+			.flags  = 0x0,
+			.len	= sizeof(buf),
+			.buf	= buf,
+		},
+		{
+			.addr	= client->addr,
+			.flags  = I2C_M_RD,
+			.buf	= data,
+		},
+	};
+	u32 rlen, rem_len = len, max_read_len = len;
+	int status;
+
+	/* check any max_read_len limitation on i2c adapter */
+	if (quirks && quirks->max_read_len)
+		max_read_len = quirks->max_read_len;
+
+	while (rem_len > 0) {
+		msgs[1].buf = &data[len - rem_len];
+		rlen = min_t(u16, rem_len, max_read_len);
+		msgs[1].len = rlen;
+		put_unaligned_le16(rab, buf);
+		status = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+		if (status < 0) {
+			dev_err(uc->dev, "i2c_transfer failed %d\n", status);
+			return status;
+		}
+		rab += rlen;
+		rem_len -= rlen;
+	}
+
+	return 0;
+}
+
+static int ccg_write(struct ucsi_ccg *uc, u16 rab, u8 *data, u32 len)
+{
+	struct i2c_client *client = uc->client;
+	unsigned char *buf;
+	struct i2c_msg msgs[] = {
+		{
+			.addr	= client->addr,
+			.flags  = 0x0,
+		}
+	};
+	int status;
+
+	buf = kzalloc(len + sizeof(rab), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	put_unaligned_le16(rab, buf);
+	memcpy(buf + sizeof(rab), data, len);
+
+	msgs[0].len = len + sizeof(rab);
+	msgs[0].buf = buf;
+
+	status = i2c_transfer(client->adapter, msgs, ARRAY_SIZE(msgs));
+	if (status < 0) {
+		dev_err(uc->dev, "i2c_transfer failed %d\n", status);
+		kfree(buf);
+		return status;
+	}
+
+	kfree(buf);
+	return 0;
+}
+
+static int ucsi_ccg_init(struct ucsi_ccg *uc)
+{
+	unsigned int count = 10;
+	u8 data;
+	int status;
+
+	data = CCGX_RAB_UCSI_CONTROL_STOP;
+	status = ccg_write(uc, CCGX_RAB_UCSI_CONTROL, &data, sizeof(data));
+	if (status < 0)
+		return status;
+
+	data = CCGX_RAB_UCSI_CONTROL_START;
+	status = ccg_write(uc, CCGX_RAB_UCSI_CONTROL, &data, sizeof(data));
+	if (status < 0)
+		return status;
+
+	/*
+	 * Flush CCGx RESPONSE queue by acking interrupts. Above ucsi control
+	 * register write will push response which must be cleared.
+	 */
+	do {
+		status = ccg_read(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));
+		if (status < 0)
+			return status;
+
+		if (!data)
+			return 0;
+
+		status = ccg_write(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));
+		if (status < 0)
+			return status;
+
+		usleep_range(10000, 11000);
+	} while (--count);
+
+	return -ETIMEDOUT;
+}
+
+static int ucsi_ccg_send_data(struct ucsi_ccg *uc)
+{
+	u8 *ppm = (u8 *)uc->ppm.data;
+	int status;
+	u16 rab;
+
+	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data, message_out));
+	status = ccg_write(uc, rab, ppm +
+			   offsetof(struct ucsi_data, message_out),
+			   sizeof(uc->ppm.data->message_out));
+	if (status < 0)
+		return status;
+
+	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data, ctrl));
+	return ccg_write(uc, rab, ppm + offsetof(struct ucsi_data, ctrl),
+			 sizeof(uc->ppm.data->ctrl));
+}
+
+static int ucsi_ccg_recv_data(struct ucsi_ccg *uc)
+{
+	u8 *ppm = (u8 *)uc->ppm.data;
+	int status;
+	u16 rab;
+
+	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data, cci));
+	status = ccg_read(uc, rab, ppm + offsetof(struct ucsi_data, cci),
+			  sizeof(uc->ppm.data->cci));
+	if (status < 0)
+		return status;
+
+	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data, message_in));
+	return ccg_read(uc, rab, ppm + offsetof(struct ucsi_data, message_in),
+			sizeof(uc->ppm.data->message_in));
+}
+
+static int ucsi_ccg_ack_interrupt(struct ucsi_ccg *uc)
+{
+	int status;
+	unsigned char data;
+
+	status = ccg_read(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));
+	if (status < 0)
+		return status;
+
+	return ccg_write(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));
+}
+
+static int ucsi_ccg_sync(struct ucsi_ppm *ppm)
+{
+	struct ucsi_ccg *uc = container_of(ppm, struct ucsi_ccg, ppm);
+	int status;
+
+	status = ucsi_ccg_recv_data(uc);
+	if (status < 0)
+		return status;
+
+	/* ack interrupt to allow next command to run */
+	return ucsi_ccg_ack_interrupt(uc);
+}
+
+static int ucsi_ccg_cmd(struct ucsi_ppm *ppm, struct ucsi_control *ctrl)
+{
+	struct ucsi_ccg *uc = container_of(ppm, struct ucsi_ccg, ppm);
+
+	ppm->data->ctrl.raw_cmd = ctrl->raw_cmd;
+	return ucsi_ccg_send_data(uc);
+}
+
+static irqreturn_t ccg_irq_handler(int irq, void *data)
+{
+	struct ucsi_ccg *uc = data;
+
+	ucsi_notify(uc->ucsi);
+
+	return IRQ_HANDLED;
+}
+
+static int ucsi_ccg_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct ucsi_ccg *uc;
+	int status;
+	u16 rab;
+
+	uc = devm_kzalloc(dev, sizeof(*uc), GFP_KERNEL);
+	if (!uc)
+		return -ENOMEM;
+
+	uc->ppm.data = devm_kzalloc(dev, sizeof(struct ucsi_data), GFP_KERNEL);
+	if (!uc->ppm.data)
+		return -ENOMEM;
+
+	uc->ppm.cmd = ucsi_ccg_cmd;
+	uc->ppm.sync = ucsi_ccg_sync;
+	uc->dev = dev;
+	uc->client = client;
+
+	/* reset ccg device and initialize ucsi */
+	status = ucsi_ccg_init(uc);
+	if (status < 0) {
+		dev_err(uc->dev, "ucsi_ccg_init failed - %d\n", status);
+		return status;
+	}
+
+	status = devm_request_threaded_irq(dev, client->irq, NULL,
+					   ccg_irq_handler,
+					   IRQF_ONESHOT | IRQF_TRIGGER_HIGH,
+					   dev_name(dev), uc);
+	if (status < 0) {
+		dev_err(uc->dev, "request_threaded_irq failed - %d\n", status);
+		return status;
+	}
+
+	uc->ucsi = ucsi_register_ppm(dev, &uc->ppm);
+	if (IS_ERR(uc->ucsi)) {
+		dev_err(uc->dev, "ucsi_register_ppm failed\n");
+		return PTR_ERR(uc->ucsi);
+	}
+
+	rab = CCGX_RAB_UCSI_DATA_BLOCK(offsetof(struct ucsi_data, version));
+	status = ccg_read(uc, rab, (u8 *)(uc->ppm.data) +
+			  offsetof(struct ucsi_data, version),
+			  sizeof(uc->ppm.data->version));
+	if (status < 0) {
+		ucsi_unregister_ppm(uc->ucsi);
+		return status;
+	}
+
+	i2c_set_clientdata(client, uc);
+	return 0;
+}
+
+static int ucsi_ccg_remove(struct i2c_client *client)
+{
+	struct ucsi_ccg *uc = i2c_get_clientdata(client);
+
+	ucsi_unregister_ppm(uc->ucsi);
+
+	return 0;
+}
+
+static const struct i2c_device_id ucsi_ccg_device_id[] = {
+	{"ccgx-ucsi", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, ucsi_ccg_device_id);
+
+static struct i2c_driver ucsi_ccg_driver = {
+	.driver = {
+		.name = "ucsi_ccg",
+	},
+	.probe = ucsi_ccg_probe,
+	.remove = ucsi_ccg_remove,
+	.id_table = ucsi_ccg_device_id,
+};
+
+module_i2c_driver(ucsi_ccg_driver);
+
+MODULE_AUTHOR("Ajay Gupta <ajayg@nvidia.com>");
+MODULE_DESCRIPTION("UCSI driver for Cypress CCGx Type-C controller");
+MODULE_LICENSE("GPL v2");