1 files changed, 311 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-taos-evm.c b/drivers/i2c/busses/i2c-taos-evm.c
new file mode 100644
index 000000000..b0f012079
--- /dev/null
+++ b/drivers/i2c/busses/i2c-taos-evm.c
@@ -0,0 +1,311 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Driver for the TAOS evaluation modules
+ * These devices include an I2C master which can be controlled over the
+ * serial port.
+ *
+ * Copyright (C) 2007 Jean Delvare <jdelvare@suse.de>
+ */
+
+#include <linux/delay.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/input.h>
+#include <linux/serio.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+
+#define TAOS_BUFFER_SIZE	63
+
+#define TAOS_STATE_INIT		0
+#define TAOS_STATE_IDLE		1
+#define TAOS_STATE_EOFF		2
+#define TAOS_STATE_RECV		3
+
+#define TAOS_CMD_RESET		0x12
+#define TAOS_CMD_ECHO_ON	'+'
+#define TAOS_CMD_ECHO_OFF	'-'
+
+static DECLARE_WAIT_QUEUE_HEAD(wq);
+
+struct taos_data {
+	struct i2c_adapter adapter;
+	struct i2c_client *client;
+	int state;
+	u8 addr;		/* last used address */
+	unsigned char buffer[TAOS_BUFFER_SIZE];
+	unsigned int pos;	/* position inside the buffer */
+};
+
+/* TAOS TSL2550 EVM */
+static const struct i2c_board_info tsl2550_info = {
+	I2C_BOARD_INFO("tsl2550", 0x39),
+};
+
+/* Instantiate i2c devices based on the adapter name */
+static struct i2c_client *taos_instantiate_device(struct i2c_adapter *adapter)
+{
+	if (!strncmp(adapter->name, "TAOS TSL2550 EVM", 16)) {
+		dev_info(&adapter->dev, "Instantiating device %s at 0x%02x\n",
+			tsl2550_info.type, tsl2550_info.addr);
+		return i2c_new_client_device(adapter, &tsl2550_info);
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+
+static int taos_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
+			   unsigned short flags, char read_write, u8 command,
+			   int size, union i2c_smbus_data *data)
+{
+	struct serio *serio = adapter->algo_data;
+	struct taos_data *taos = serio_get_drvdata(serio);
+	char *p;
+
+	/* Encode our transaction. "@" is for the device address, "$" for the
+	   SMBus command and "#" for the data. */
+	p = taos->buffer;
+
+	/* The device remembers the last used address, no need to send it
+	   again if it's the same */
+	if (addr != taos->addr)
+		p += sprintf(p, "@%02X", addr);
+
+	switch (size) {
+	case I2C_SMBUS_BYTE:
+		if (read_write == I2C_SMBUS_WRITE)
+			sprintf(p, "$#%02X", command);
+		else
+			sprintf(p, "$");
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		if (read_write == I2C_SMBUS_WRITE)
+			sprintf(p, "$%02X#%02X", command, data->byte);
+		else
+			sprintf(p, "$%02X", command);
+		break;
+	default:
+		dev_warn(&adapter->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	/* Send the transaction to the TAOS EVM */
+	dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
+	for (p = taos->buffer; *p; p++)
+		serio_write(serio, *p);
+
+	taos->addr = addr;
+
+	/* Start the transaction and read the answer */
+	taos->pos = 0;
+	taos->state = TAOS_STATE_RECV;
+	serio_write(serio, read_write == I2C_SMBUS_WRITE ? '>' : '<');
+	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
+					 msecs_to_jiffies(150));
+	if (taos->state != TAOS_STATE_IDLE
+	 || taos->pos != 5) {
+		dev_err(&adapter->dev, "Transaction timeout (pos=%d)\n",
+			taos->pos);
+		return -EIO;
+	}
+	dev_dbg(&adapter->dev, "Answer buffer: %s\n", taos->buffer);
+
+	/* Interpret the returned string */
+	p = taos->buffer + 1;
+	p[3] = '\0';
+	if (!strcmp(p, "NAK"))
+		return -ENODEV;
+
+	if (read_write == I2C_SMBUS_WRITE) {
+		if (!strcmp(p, "ACK"))
+			return 0;
+	} else {
+		if (p[0] == 'x') {
+			/*
+			 * Voluntarily dropping error code of kstrtou8 since all
+			 * error code that it could return are invalid according
+			 * to Documentation/i2c/fault-codes.rst.
+			 */
+			if (kstrtou8(p + 1, 16, &data->byte))
+				return -EPROTO;
+			return 0;
+		}
+	}
+
+	return -EIO;
+}
+
+static u32 taos_smbus_func(struct i2c_adapter *adapter)
+{
+	return I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA;
+}
+
+static const struct i2c_algorithm taos_algorithm = {
+	.smbus_xfer	= taos_smbus_xfer,
+	.functionality	= taos_smbus_func,
+};
+
+static irqreturn_t taos_interrupt(struct serio *serio, unsigned char data,
+				  unsigned int flags)
+{
+	struct taos_data *taos = serio_get_drvdata(serio);
+
+	switch (taos->state) {
+	case TAOS_STATE_INIT:
+		taos->buffer[taos->pos++] = data;
+		if (data == ':'
+		 || taos->pos == TAOS_BUFFER_SIZE - 1) {
+			taos->buffer[taos->pos] = '\0';
+			taos->state = TAOS_STATE_IDLE;
+			wake_up_interruptible(&wq);
+		}
+		break;
+	case TAOS_STATE_EOFF:
+		taos->state = TAOS_STATE_IDLE;
+		wake_up_interruptible(&wq);
+		break;
+	case TAOS_STATE_RECV:
+		taos->buffer[taos->pos++] = data;
+		if (data == ']') {
+			taos->buffer[taos->pos] = '\0';
+			taos->state = TAOS_STATE_IDLE;
+			wake_up_interruptible(&wq);
+		}
+		break;
+	}
+
+	return IRQ_HANDLED;
+}
+
+/* Extract the adapter name from the buffer received after reset.
+   The buffer is modified and a pointer inside the buffer is returned. */
+static char *taos_adapter_name(char *buffer)
+{
+	char *start, *end;
+
+	start = strstr(buffer, "TAOS ");
+	if (!start)
+		return NULL;
+
+	end = strchr(start, '\r');
+	if (!end)
+		return NULL;
+	*end = '\0';
+
+	return start;
+}
+
+static int taos_connect(struct serio *serio, struct serio_driver *drv)
+{
+	struct taos_data *taos;
+	struct i2c_adapter *adapter;
+	char *name;
+	int err;
+
+	taos = kzalloc(sizeof(struct taos_data), GFP_KERNEL);
+	if (!taos) {
+		err = -ENOMEM;
+		goto exit;
+	}
+	taos->state = TAOS_STATE_INIT;
+	serio_set_drvdata(serio, taos);
+
+	err = serio_open(serio, drv);
+	if (err)
+		goto exit_kfree;
+
+	adapter = &taos->adapter;
+	adapter->owner = THIS_MODULE;
+	adapter->algo = &taos_algorithm;
+	adapter->algo_data = serio;
+	adapter->dev.parent = &serio->dev;
+
+	/* Reset the TAOS evaluation module to identify it */
+	serio_write(serio, TAOS_CMD_RESET);
+	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
+					 msecs_to_jiffies(2000));
+
+	if (taos->state != TAOS_STATE_IDLE) {
+		err = -ENODEV;
+		dev_err(&serio->dev, "TAOS EVM reset failed (state=%d, "
+			"pos=%d)\n", taos->state, taos->pos);
+		goto exit_close;
+	}
+
+	name = taos_adapter_name(taos->buffer);
+	if (!name) {
+		err = -ENODEV;
+		dev_err(&serio->dev, "TAOS EVM identification failed\n");
+		goto exit_close;
+	}
+	strscpy(adapter->name, name, sizeof(adapter->name));
+
+	/* Turn echo off for better performance */
+	taos->state = TAOS_STATE_EOFF;
+	serio_write(serio, TAOS_CMD_ECHO_OFF);
+
+	wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
+					 msecs_to_jiffies(250));
+	if (taos->state != TAOS_STATE_IDLE) {
+		err = -ENODEV;
+		dev_err(&serio->dev, "TAOS EVM echo off failed "
+			"(state=%d)\n", taos->state);
+		goto exit_close;
+	}
+
+	err = i2c_add_adapter(adapter);
+	if (err)
+		goto exit_close;
+	dev_info(&serio->dev, "Connected to TAOS EVM\n");
+
+	taos->client = taos_instantiate_device(adapter);
+	return 0;
+
+ exit_close:
+	serio_close(serio);
+ exit_kfree:
+	kfree(taos);
+ exit:
+	return err;
+}
+
+static void taos_disconnect(struct serio *serio)
+{
+	struct taos_data *taos = serio_get_drvdata(serio);
+
+	i2c_unregister_device(taos->client);
+	i2c_del_adapter(&taos->adapter);
+	serio_close(serio);
+	kfree(taos);
+
+	dev_info(&serio->dev, "Disconnected from TAOS EVM\n");
+}
+
+static const struct serio_device_id taos_serio_ids[] = {
+	{
+		.type	= SERIO_RS232,
+		.proto	= SERIO_TAOSEVM,
+		.id	= SERIO_ANY,
+		.extra	= SERIO_ANY,
+	},
+	{ 0 }
+};
+MODULE_DEVICE_TABLE(serio, taos_serio_ids);
+
+static struct serio_driver taos_drv = {
+	.driver		= {
+		.name	= "taos-evm",
+	},
+	.description	= "TAOS evaluation module driver",
+	.id_table	= taos_serio_ids,
+	.connect	= taos_connect,
+	.disconnect	= taos_disconnect,
+	.interrupt	= taos_interrupt,
+};
+
+module_serio_driver(taos_drv);
+
+MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
+MODULE_DESCRIPTION("TAOS evaluation module driver");
+MODULE_LICENSE("GPL");