[PATCH] W1: Add the DS2482 I2C-to-w1 bridge driver.

Signed-off-by: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

Documentation/w1/masters/ds2482

+Kernel driver ds2482
+====================
+
+Supported chips:
+  * Maxim DS2482-100, Maxim DS2482-800
+    Prefix: 'ds2482'
+    Addresses scanned: None
+    Datasheets:
+        http://pdfserv.maxim-ic.com/en/ds/DS2482-100-DS2482S-100.pdf
+        http://pdfserv.maxim-ic.com/en/ds/DS2482-800-DS2482S-800.pdf
+
+Author: Ben Gardner <bgardner@wabtec.com>
+
+
+Description
+-----------
+
+The Maixm/Dallas Semiconductor DS2482 is a I2C device that provides
+one (DS2482-100) or eight (DS2482-800) 1-wire busses.
+
+
+General Remarks
+---------------
+
+Valid addresses are 0x18, 0x19, 0x1a, and 0x1b.
+However, the device cannot be detected without writing to the i2c bus, so no
+detection is done.
+You should force the device address.
+
+$ modprobe ds2482 force=0,0x18
+

drivers/w1/masters/Kconfig

@@ -34,5 +34,15 @@ config W1_MASTER_DS9490_BRIDGE
 	  This support is also available as a module.  If so, the module
 	  will be called ds_w1_bridge.ko.
 
+config W1_MASTER_DS2482
+	tristate "Maxim DS2482 I2C to 1-Wire bridge"
+	depends on I2C && W1 && EXPERIMENTAL
+	help
+	  If you say yes here you get support for the Maxim DS2482
+	  I2C to 1-Wire bridge.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called ds2482.
+
 endmenu
 

drivers/w1/masters/Makefile

@@ -9,3 +9,5 @@ ds9490r-objs    := dscore.o
 
 obj-$(CONFIG_W1_MASTER_DS9490_BRIDGE)	+= ds_w1_bridge.o
 
+obj-$(CONFIG_W1_MASTER_DS2482)		+= ds2482.o
+

drivers/w1/masters/ds2482.c

+/**
+ * ds2482.c - provides i2c to w1-master bridge(s)
+ * Copyright (C) 2005  Ben Gardner <bgardner@wabtec.com>
+ *
+ * The DS2482 is a sensor chip made by Dallas Semiconductor (Maxim).
+ * It is a I2C to 1-wire bridge.
+ * There are two variations: -100 and -800, which have 1 or 8 1-wire ports.
+ * The complete datasheet can be obtained from MAXIM's website at:
+ *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/delay.h>
+#include <asm/delay.h>
+
+#include "../w1.h"
+#include "../w1_int.h"
+
+/**
+ * Address is selected using 2 pins, resulting in 4 possible addresses.
+ *  0x18, 0x19, 0x1a, 0x1b
+ * However, the chip cannot be detected without doing an i2c write,
+ * so use the force module parameter.
+ */
+static unsigned short normal_i2c[] = {I2C_CLIENT_END};
+
+/**
+ * Insmod parameters
+ */
+I2C_CLIENT_INSMOD_1(ds2482);
+
+/**
+ * The DS2482 registers - there are 3 registers that are addressed by a read
+ * pointer. The read pointer is set by the last command executed.
+ *
+ * To read the data, issue a register read for any address
+ */
+#define DS2482_CMD_RESET		0xF0	/* No param */
+#define DS2482_CMD_SET_READ_PTR		0xE1	/* Param: DS2482_PTR_CODE_xxx */
+#define DS2482_CMD_CHANNEL_SELECT	0xC3	/* Param: Channel byte - DS2482-800 only */
+#define DS2482_CMD_WRITE_CONFIG		0xD2	/* Param: Config byte */
+#define DS2482_CMD_1WIRE_RESET		0xB4	/* Param: None */
+#define DS2482_CMD_1WIRE_SINGLE_BIT	0x87	/* Param: Bit byte (bit7) */
+#define DS2482_CMD_1WIRE_WRITE_BYTE	0xA5	/* Param: Data byte */
+#define DS2482_CMD_1WIRE_READ_BYTE	0x96	/* Param: None */
+/* Note to read the byte, Set the ReadPtr to Data then read (any addr) */
+#define DS2482_CMD_1WIRE_TRIPLET	0x78	/* Param: Dir byte (bit7) */
+
+/* Values for DS2482_CMD_SET_READ_PTR */
+#define DS2482_PTR_CODE_STATUS		0xF0
+#define DS2482_PTR_CODE_DATA		0xE1
+#define DS2482_PTR_CODE_CHANNEL		0xD2	/* DS2482-800 only */
+#define DS2482_PTR_CODE_CONFIG		0xC3
+
+/**
+ * Configure Register bit definitions
+ * The top 4 bits always read 0.
+ * To write, the top nibble must be the 1's compl. of the low nibble.
+ */
+#define DS2482_REG_CFG_1WS		0x08
+#define DS2482_REG_CFG_SPU		0x04
+#define DS2482_REG_CFG_PPM		0x02
+#define DS2482_REG_CFG_APU		0x01
+
+
+/**
+ * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
+ * To set the channel, write the value at the index of the channel.
+ * Read and compare against the corresponding value to verify the change.
+ */
+static const u8 ds2482_chan_wr[8] =
+	{ 0xF0, 0xE1, 0xD2, 0xC3, 0xB4, 0xA5, 0x96, 0x87 };
+static const u8 ds2482_chan_rd[8] =
+	{ 0xB8, 0xB1, 0xAA, 0xA3, 0x9C, 0x95, 0x8E, 0x87 };
+
+
+/**
+ * Status Register bit definitions (read only)
+ */
+#define DS2482_REG_STS_DIR		0x80
+#define DS2482_REG_STS_TSB		0x40
+#define DS2482_REG_STS_SBR		0x20
+#define DS2482_REG_STS_RST		0x10
+#define DS2482_REG_STS_LL		0x08
+#define DS2482_REG_STS_SD		0x04
+#define DS2482_REG_STS_PPD		0x02
+#define DS2482_REG_STS_1WB		0x01
+
+
+static int ds2482_attach_adapter(struct i2c_adapter *adapter);
+static int ds2482_detect(struct i2c_adapter *adapter, int address, int kind);
+static int ds2482_detach_client(struct i2c_client *client);
+
+
+/**
+ * Driver data (common to all clients)
+ */
+static struct i2c_driver ds2482_driver = {
+	.driver = {
+		.owner	= THIS_MODULE,
+		.name	= "ds2482",
+	},
+	.attach_adapter	= ds2482_attach_adapter,
+	.detach_client	= ds2482_detach_client,
+};
+
+/*
+ * Client data (each client gets its own)
+ */
+
+struct ds2482_data;
+
+struct ds2482_w1_chan {
+	struct ds2482_data	*pdev;
+	u8			channel;
+	struct w1_bus_master	w1_bm;
+};
+
+struct ds2482_data {
+	struct i2c_client	client;
+	struct semaphore	access_lock;
+
+	/* 1-wire interface(s) */
+	int			w1_count;	/* 1 or 8 */
+	struct ds2482_w1_chan	w1_ch[8];
+
+	/* per-device values */
+	u8			channel;
+	u8			read_prt;	/* see DS2482_PTR_CODE_xxx */
+	u8			reg_config;
+};
+
+
+/**
+ * Sets the read pointer.
+ * @param pdev		The ds2482 client pointer
+ * @param read_ptr	see DS2482_PTR_CODE_xxx above
+ * @return -1 on failure, 0 on success
+ */
+static inline int ds2482_select_register(struct ds2482_data *pdev, u8 read_ptr)
+{
+	if (pdev->read_prt != read_ptr) {
+		if (i2c_smbus_write_byte_data(&pdev->client,
+					      DS2482_CMD_SET_READ_PTR,
+					      read_ptr) < 0)
+			return -1;
+
+		pdev->read_prt = read_ptr;
+	}
+	return 0;
+}
+
+/**
+ * Sends a command without a parameter
+ * @param pdev	The ds2482 client pointer
+ * @param cmd	DS2482_CMD_RESET,
+ *		DS2482_CMD_1WIRE_RESET,
+ *		DS2482_CMD_1WIRE_READ_BYTE
+ * @return -1 on failure, 0 on success
+ */
+static inline int ds2482_send_cmd(struct ds2482_data *pdev, u8 cmd)
+{
+	if (i2c_smbus_write_byte(&pdev->client, cmd) < 0)
+		return -1;
+
+	pdev->read_prt = DS2482_PTR_CODE_STATUS;
+	return 0;
+}
+
+/**
+ * Sends a command with a parameter
+ * @param pdev	The ds2482 client pointer
+ * @param cmd	DS2482_CMD_WRITE_CONFIG,
+ *		DS2482_CMD_1WIRE_SINGLE_BIT,
+ *		DS2482_CMD_1WIRE_WRITE_BYTE,
+ *		DS2482_CMD_1WIRE_TRIPLET
+ * @param byte	The data to send
+ * @return -1 on failure, 0 on success
+ */
+static inline int ds2482_send_cmd_data(struct ds2482_data *pdev,
+				       u8 cmd, u8 byte)
+{
+	if (i2c_smbus_write_byte_data(&pdev->client, cmd, byte) < 0)
+		return -1;
+
+	/* all cmds leave in STATUS, except CONFIG */
+	pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?
+			 DS2482_PTR_CODE_STATUS : DS2482_PTR_CODE_CONFIG;
+	return 0;
+}
+
+
+/*
+ * 1-Wire interface code
+ */
+
+#define DS2482_WAIT_IDLE_TIMEOUT	100
+
+/**
+ * Waits until the 1-wire interface is idle (not busy)
+ *
+ * @param pdev Pointer to the device structure
+ * @return the last value read from status or -1 (failure)
+ */
+static int ds2482_wait_1wire_idle(struct ds2482_data *pdev)
+{
+	int temp = -1;
+	int retries = 0;
+
+	if (!ds2482_select_register(pdev, DS2482_PTR_CODE_STATUS)) {
+		do {
+			temp = i2c_smbus_read_byte(&pdev->client);
+		} while ((temp >= 0) && (temp & DS2482_REG_STS_1WB) &&
+			 (++retries > DS2482_WAIT_IDLE_TIMEOUT));
+	}
+
+	if (retries > DS2482_WAIT_IDLE_TIMEOUT)
+		printk(KERN_ERR "%s: timeout on channel %d\n",
+		       __func__, pdev->channel);
+
+	return temp;
+}
+
+/**
+ * Selects a w1 channel.
+ * The 1-wire interface must be idle before calling this function.
+ *
+ * @param pdev		The ds2482 client pointer
+ * @param channel	0-7
+ * @return		-1 (failure) or 0 (success)
+ */
+static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel)
+{
+	if (i2c_smbus_write_byte_data(&pdev->client, DS2482_CMD_CHANNEL_SELECT,
+				      ds2482_chan_wr[channel]) < 0)
+		return -1;
+
+	pdev->read_prt = DS2482_PTR_CODE_CHANNEL;
+	pdev->channel = -1;
+	if (i2c_smbus_read_byte(&pdev->client) == ds2482_chan_rd[channel]) {
+		pdev->channel = channel;
+		return 0;
+	}
+	return -1;
+}
+
+
+/**
+ * Performs the touch-bit function, which writes a 0 or 1 and reads the level.
+ *
+ * @param data	The ds2482 channel pointer
+ * @param bit	The level to write: 0 or non-zero
+ * @return	The level read: 0 or 1
+ */
+static u8 ds2482_w1_touch_bit(void *data, u8 bit)
+{
+	struct ds2482_w1_chan *pchan = data;
+	struct ds2482_data    *pdev = pchan->pdev;
+	int status = -1;
+
+	down(&pdev->access_lock);
+
+	/* Select the channel */
+	ds2482_wait_1wire_idle(pdev);
+	if (pdev->w1_count > 1)
+		ds2482_set_channel(pdev, pchan->channel);
+
+	/* Send the touch command, wait until 1WB == 0, return the status */
+	if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_SINGLE_BIT,
+				  bit ? 0xFF : 0))
+		status = ds2482_wait_1wire_idle(pdev);
+
+	up(&pdev->access_lock);
+
+	return (status & DS2482_REG_STS_SBR) ? 1 : 0;
+}
+
+/**
+ * Performs the triplet function, which reads two bits and writes a bit.
+ * The bit written is determined by the two reads:
+ *   00 => dbit, 01 => 0, 10 => 1
+ *
+ * @param data	The ds2482 channel pointer
+ * @param dbit	The direction to choose if both branches are valid
+ * @return	b0=read1 b1=read2 b3=bit written
+ */
+static u8 ds2482_w1_triplet(void *data, u8 dbit)
+{
+	struct ds2482_w1_chan *pchan = data;
+	struct ds2482_data    *pdev = pchan->pdev;
+	int status = (3 << 5);
+
+	down(&pdev->access_lock);
+
+	/* Select the channel */
+	ds2482_wait_1wire_idle(pdev);
+	if (pdev->w1_count > 1)
+		ds2482_set_channel(pdev, pchan->channel);
+
+	/* Send the triplet command, wait until 1WB == 0, return the status */
+	if (!ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_TRIPLET,
+				  dbit ? 0xFF : 0))
+		status = ds2482_wait_1wire_idle(pdev);
+
+	up(&pdev->access_lock);
+
+	/* Decode the status */
+	return (status >> 5);
+}
+
+/**
+ * Performs the write byte function.
+ *
+ * @param data	The ds2482 channel pointer
+ * @param byte	The value to write
+ */
+static void ds2482_w1_write_byte(void *data, u8 byte)
+{
+	struct ds2482_w1_chan *pchan = data;
+	struct ds2482_data    *pdev = pchan->pdev;
+
+	down(&pdev->access_lock);
+
+	/* Select the channel */
+	ds2482_wait_1wire_idle(pdev);
+	if (pdev->w1_count > 1)
+		ds2482_set_channel(pdev, pchan->channel);
+
+	/* Send the write byte command */
+	ds2482_send_cmd_data(pdev, DS2482_CMD_1WIRE_WRITE_BYTE, byte);
+
+	up(&pdev->access_lock);
+}
+
+/**
+ * Performs the read byte function.
+ *
+ * @param data	The ds2482 channel pointer
+ * @return	The value read
+ */
+static u8 ds2482_w1_read_byte(void *data)
+{
+	struct ds2482_w1_chan *pchan = data;
+	struct ds2482_data    *pdev = pchan->pdev;
+	int result;
+
+	down(&pdev->access_lock);
+
+	/* Select the channel */
+	ds2482_wait_1wire_idle(pdev);
+	if (pdev->w1_count > 1)
+		ds2482_set_channel(pdev, pchan->channel);
+
+	/* Send the read byte command */
+	ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_READ_BYTE);
+
+	/* Wait until 1WB == 0 */
+	ds2482_wait_1wire_idle(pdev);
+
+	/* Select the data register */
+	ds2482_select_register(pdev, DS2482_PTR_CODE_DATA);
+
+	/* Read the data byte */
+	result = i2c_smbus_read_byte(&pdev->client);
+
+	up(&pdev->access_lock);
+
+	return result;
+}
+
+
+/**
+ * Sends a reset on the 1-wire interface
+ *
+ * @param data	The ds2482 channel pointer
+ * @return	0=Device present, 1=No device present or error
+ */
+static u8 ds2482_w1_reset_bus(void *data)
+{
+	struct ds2482_w1_chan *pchan = data;
+	struct ds2482_data    *pdev = pchan->pdev;
+	int err;
+	u8 retval = 1;
+
+	down(&pdev->access_lock);
+
+	/* Select the channel */
+	ds2482_wait_1wire_idle(pdev);
+	if (pdev->w1_count > 1)
+		ds2482_set_channel(pdev, pchan->channel);
+
+	/* Send the reset command */
+	err = ds2482_send_cmd(pdev, DS2482_CMD_1WIRE_RESET);
+	if (err >= 0) {
+		/* Wait until the reset is complete */
+		err = ds2482_wait_1wire_idle(pdev);
+		retval = !(err & DS2482_REG_STS_PPD);
+
+		/* If the chip did reset since detect, re-config it */
+		if (err & DS2482_REG_STS_RST)
+			ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
+					     0xF0);
+	}
+
+	up(&pdev->access_lock);
+
+	return retval;
+}
+
+
+/**
+ * Called to see if the device exists on an i2c bus.
+ */
+static int ds2482_attach_adapter(struct i2c_adapter *adapter)
+{
+	return i2c_probe(adapter, &addr_data, ds2482_detect);
+}
+
+
+/*
+ * The following function does more than just detection. If detection
+ * succeeds, it also registers the new chip.
+ */
+static int ds2482_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+	struct ds2482_data *data;
+	struct i2c_client  *new_client;
+	int err = 0;
+	int temp1;
+	int idx;
+
+	if (!i2c_check_functionality(adapter,
+				     I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
+				     I2C_FUNC_SMBUS_BYTE))
+		goto exit;
+
+	if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto exit;
+	}
+
+	new_client = &data->client;
+	i2c_set_clientdata(new_client, data);
+	new_client->addr = address;
+	new_client->driver = &ds2482_driver;
+	new_client->adapter = adapter;
+
+	/* Reset the device (sets the read_ptr to status) */
+	if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
+		dev_dbg(&adapter->dev, "DS2482 reset failed at 0x%02x.\n",
+			address);
+		goto exit_free;
+	}
+
+	/* Sleep at least 525ns to allow the reset to complete */
+	ndelay(525);
+
+	/* Read the status byte - only reset bit and line should be set */
+	temp1 = i2c_smbus_read_byte(new_client);
+	if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
+		dev_dbg(&adapter->dev, "DS2482 (0x%02x) reset status "
+			"0x%02X - not a DS2482\n", address, temp1);
+		goto exit_free;
+	}
+
+	/* Detect the 8-port version */
+	data->w1_count = 1;
+	if (ds2482_set_channel(data, 7) == 0)
+		data->w1_count = 8;
+
+	/* Set all config items to 0 (off) */
+	ds2482_send_cmd_data(data, DS2482_CMD_WRITE_CONFIG, 0xF0);
+
+	/* We can fill in the remaining client fields */
+	snprintf(new_client->name, sizeof(new_client->name), "ds2482-%d00",
+		 data->w1_count);
+
+	init_MUTEX(&data->access_lock);
+
+	/* Tell the I2C layer a new client has arrived */
+	if ((err = i2c_attach_client(new_client)))
+		goto exit_free;
+
+	/* Register 1-wire interface(s) */
+	for (idx = 0; idx < data->w1_count; idx++) {
+		data->w1_ch[idx].pdev = data;
+		data->w1_ch[idx].channel = idx;
+
+		/* Populate all the w1 bus master stuff */
+		data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];
+		data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;
+		data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;
+		data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;
+		data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;
+		data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;
+
+		err = w1_add_master_device(&data->w1_ch[idx].w1_bm);
+		if (err) {
+			data->w1_ch[idx].pdev = NULL;
+			goto exit_w1_remove;
+		}
+	}
+
+	return 0;
+
+exit_w1_remove:
+	i2c_detach_client(new_client);
+
+	for (idx = 0; idx < data->w1_count; idx++) {
+		if (data->w1_ch[idx].pdev != NULL)
+			w1_remove_master_device(&data->w1_ch[idx].w1_bm);
+	}
+exit_free:
+	kfree(data);
+exit:
+	return err;
+}
+
+static int ds2482_detach_client(struct i2c_client *client)
+{
+	struct ds2482_data   *data = i2c_get_clientdata(client);
+	int err, idx;
+
+	/* Unregister the 1-wire bridge(s) */
+	for (idx = 0; idx < data->w1_count; idx++) {
+		if (data->w1_ch[idx].pdev != NULL)
+			w1_remove_master_device(&data->w1_ch[idx].w1_bm);
+	}
+
+	/* Detach the i2c device */
+	if ((err = i2c_detach_client(client))) {
+		dev_err(&client->dev,
+			"Deregistration failed, client not detached.\n");
+		return err;
+	}
+
+	/* Free the memory */
+	kfree(data);
+	return 0;
+}
+
+static int __init sensors_ds2482_init(void)
+{
+	return i2c_add_driver(&ds2482_driver);
+}
+
+static void __exit sensors_ds2482_exit(void)
+{
+	i2c_del_driver(&ds2482_driver);
+}
+
+MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
+MODULE_DESCRIPTION("DS2482 driver");
+MODULE_LICENSE("GPL");
+
+module_init(sensors_ds2482_init);
+module_exit(sensors_ds2482_exit);