i2c: New bus driver for the TAOS evaluation modules

This is a new I2C bus driver for the TAOS evaluation modules. Developped
and tested on the TAOS TSL2550 EVM.

Signed-off-by: Jean Delvare <khali@linux-fr.org>

5 files changed, 394 insertions, 0 deletions

diff --git a/Documentation/i2c/busses/i2c-taos-evm b/Documentation/i2c/busses/i2c-taos-evm
new file mode 100644
index 000000000000..9146e33be6dd
--- /dev/null
+++ b/Documentation/i2c/busses/i2c-taos-evm
@@ -0,0 +1,46 @@
+Kernel driver i2c-taos-evm
+
+Author: Jean Delvare <khali@linux-fr.org>
+
+This is a driver for the evaluation modules for TAOS I2C/SMBus chips.
+The modules include an SMBus master with limited capabilities, which can
+be controlled over the serial port. Virtually all evaluation modules
+are supported, but a few lines of code need to be added for each new
+module to instantiate the right I2C chip on the bus. Obviously, a driver
+for the chip in question is also needed.
+
+Currently supported devices are:
+
+* TAOS TSL2550 EVM
+
+For addtional information on TAOS products, please see
+  http://www.taosinc.com/
+
+
+Using this driver
+-----------------
+
+In order to use this driver, you'll need the serport driver, and the
+inputattach tool, which is part of the input-utils package. The following
+commands will tell the kernel that you have a TAOS EVM on the first
+serial port:
+
+# modprobe serport
+# inputattach --taos-evm /dev/ttyS0
+
+
+Technical details
+-----------------
+
+Only 4 SMBus transaction types are supported by the TAOS evaluation
+modules:
+* Receive Byte
+* Send Byte
+* Read Byte
+* Write Byte
+
+The communication protocol is text-based and pretty simple. It is
+described in a PDF document on the CD which comes with the evaluation
+module. The communication is rather slow, because the serial port has
+to operate at 1200 bps. However, I don't think this is a big concern in
+practice, as these modules are meant for evaluation and testing only.
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 165c1266fff7..c093b0700158 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -513,6 +513,22 @@ config I2C_SIS96X
           This driver can also be built as a module.  If so, the module
           will be called i2c-sis96x.
 
+config I2C_TAOS_EVM
+        tristate "TAOS evaluation module"
+        depends on EXPERIMENTAL
+        select SERIO
+        select SERIO_SERPORT
+        default n
+        help
+          This supports TAOS evaluation modules on serial port. In order to
+          use this driver, you will need the inputattach tool, which is part
+          of the input-utils package.
+
+          If unsure, say N.
+
+          This support is also available as a module.  If so, the module
+          will be called i2c-taos-evm.
+
 config I2C_STUB
         tristate "I2C/SMBus Test Stub"
         depends on EXPERIMENTAL && m
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 14d1432f698b..a49c0a386aee 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_I2C_SIS5595)	+= i2c-sis5595.o
 obj-$(CONFIG_I2C_SIS630)        += i2c-sis630.o
 obj-$(CONFIG_I2C_SIS96X)        += i2c-sis96x.o
 obj-$(CONFIG_I2C_STUB)          += i2c-stub.o
+obj-$(CONFIG_I2C_TAOS_EVM)      += i2c-taos-evm.o
 obj-$(CONFIG_I2C_TINY_USB)      += i2c-tiny-usb.o
 obj-$(CONFIG_I2C_VERSATILE)     += i2c-versatile.o
 obj-$(CONFIG_I2C_ACORN)         += i2c-acorn.o
diff --git a/drivers/i2c/busses/i2c-taos-evm.c b/drivers/i2c/busses/i2c-taos-evm.c
new file mode 100644
index 000000000000..1b0cfd5472fd
--- /dev/null
+++ b/drivers/i2c/busses/i2c-taos-evm.c
@@ -0,0 +1,330 @@
+/*
+ * 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 <khali@linux-fr.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#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_SEND         2
+#define TAOS_STATE_RECV         3
+
+#define TAOS_CMD_RESET          0x12
+
+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 struct i2c_board_info tsl2550_info = {
+        I2C_BOARD_INFO("tsl2550", 0x39),
+        .type   = "tsl2550",
+};
+
+/* 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.driver_name, tsl2550_info.addr);
+                return i2c_new_device(adapter, &tsl2550_info);
+        }
+
+        return NULL;
+}
+
+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_dbg(&adapter->dev, "Unsupported transaction size %d\n",
+                        size);
+                return -EINVAL;
+        }
+
+        /* Send the transaction to the TAOS EVM */
+        dev_dbg(&adapter->dev, "Command buffer: %s\n", taos->buffer);
+        taos->pos = 0;
+        taos->state = TAOS_STATE_SEND;
+        serio_write(serio, taos->buffer[0]);
+        wait_event_interruptible_timeout(wq, taos->state == TAOS_STATE_IDLE,
+                                         msecs_to_jiffies(250));
+        if (taos->state != TAOS_STATE_IDLE) {
+                dev_err(&adapter->dev, "Transaction failed "
+                        "(state=%d, pos=%d)\n", taos->state, taos->pos);
+                taos->addr = 0;
+                return -EIO;
+        }
+        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 != 6) {
+                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 + 2;
+        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') {
+                        data->byte = simple_strtol(p + 1, NULL, 16);
+                        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_SEND:
+                if (taos->buffer[++taos->pos])
+                        serio_write(serio, taos->buffer[taos->pos]);
+                else {
+                        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_dbg(&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;
+        }
+        strlcpy(adapter->name, name, sizeof(adapter->name));
+
+        err = i2c_add_adapter(adapter);
+        if (err)
+                goto exit_close;
+        dev_dbg(&serio->dev, "Connected to TAOS EVM\n");
+
+        taos->client = taos_instantiate_device(adapter);
+        return 0;
+
+ exit_close:
+        serio_close(serio);
+ exit_kfree:
+        serio_set_drvdata(serio, NULL);
+        kfree(taos);
+ exit:
+        return err;
+}
+
+static void taos_disconnect(struct serio *serio)
+{
+        struct taos_data *taos = serio_get_drvdata(serio);
+
+        if (taos->client)
+                i2c_unregister_device(taos->client);
+        i2c_del_adapter(&taos->adapter);
+        serio_close(serio);
+        serio_set_drvdata(serio, NULL);
+        kfree(taos);
+
+        dev_dbg(&serio->dev, "Disconnected from TAOS EVM\n");
+}
+
+static 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,
+};
+
+static int __init taos_init(void)
+{
+        return serio_register_driver(&taos_drv);
+}
+
+static void __exit taos_exit(void)
+{
+        serio_unregister_driver(&taos_drv);
+}
+
+MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
+MODULE_DESCRIPTION("TAOS evaluation module driver");
+MODULE_LICENSE("GPL");
+
+module_init(taos_init);
+module_exit(taos_exit);
diff --git a/include/linux/serio.h b/include/linux/serio.h
index 1ebf0455e224..d9377ce9ffd1 100644
--- a/include/linux/serio.h
+++ b/include/linux/serio.h
@@ -209,5 +209,6 @@ static inline void serio_unpin_driver(struct serio *serio)
 #define SERIO_PENMOUNT  0x31
 #define SERIO_TOUCHRIGHT        0x32
 #define SERIO_TOUCHWIN  0x33
+#define SERIO_TAOSEVM   0x34
 
 #endif