--- /dev/null
+/**
+ * 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"
+
+/**
+ * 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 /* 1-wire speed */
+#define DS2482_REG_CFG_SPU 0x04 /* strong pull-up */
+#define DS2482_REG_CFG_PPM 0x02 /* presence pulse masking */
+#define DS2482_REG_CFG_APU 0x01 /* active pull-up */
+
+
+/**
+ * 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_probe(struct i2c_client *client,
+ const struct i2c_device_id *id);
+static int ds2482_remove(struct i2c_client *client);
+
+
+/**
+ * Driver data (common to all clients)
+ */
+static const struct i2c_device_id ds2482_id[] = {
+ { "ds2482", 0 },
+ { }
+};
+
+static struct i2c_driver ds2482_driver = {
+ .driver = {
+ .owner = THIS_MODULE,
+ .name = "ds2482",
+ },
+ .probe = ds2482_probe,
+ .remove = ds2482_remove,
+ .id_table = ds2482_id,
+};
+
+/*
+ * 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 mutex 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;
+};
+
+
+/**
+ * Helper to calculate values for configuration register
+ * @param conf the raw config value
+ * @return the value w/ complements that can be written to register
+ */
+static inline u8 ds2482_calculate_config(u8 conf)
+{
+ return conf | ((~conf & 0x0f) << 4);
+}
+
+
+/**
+ * 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)
+ pr_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;
+
+ mutex_lock(&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);
+
+ mutex_unlock(&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);
+
+ mutex_lock(&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);
+
+ mutex_unlock(&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;
+
+ mutex_lock(&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);
+
+ mutex_unlock(&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;
+
+ mutex_lock(&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);
+
+ mutex_unlock(&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;
+
+ mutex_lock(&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,
+ ds2482_calculate_config(0x00));
+ }
+
+ mutex_unlock(&pdev->access_lock);
+
+ return retval;
+}
+
+static u8 ds2482_w1_set_pullup(void *data, int delay)
+{
+ struct ds2482_w1_chan *pchan = data;
+ struct ds2482_data *pdev = pchan->pdev;
+ u8 retval = 1;
+
+ /* if delay is non-zero activate the pullup,
+ * the strong pullup will be automatically deactivated
+ * by the master, so do not explicitly deactive it
+ */
+ if (delay) {
+ /* both waits are crucial, otherwise devices might not be
+ * powered long enough, causing e.g. a w1_therm sensor to
+ * provide wrong conversion results
+ */
+ ds2482_wait_1wire_idle(pdev);
+ /* note: it seems like both SPU and APU have to be set! */
+ retval = ds2482_send_cmd_data(pdev, DS2482_CMD_WRITE_CONFIG,
+ ds2482_calculate_config(DS2482_REG_CFG_SPU |
+ DS2482_REG_CFG_APU));
+ ds2482_wait_1wire_idle(pdev);
+ }
+
+ return retval;
+}
+
+
+static int ds2482_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct ds2482_data *data;
+ int err = -ENODEV;
+ int temp1;
+ int idx;
+
+ if (!i2c_check_functionality(client->adapter,
+ I2C_FUNC_SMBUS_WRITE_BYTE_DATA |
+ I2C_FUNC_SMBUS_BYTE))
+ return -ENODEV;
+
+ if (!(data = kzalloc(sizeof(struct ds2482_data), GFP_KERNEL))) {
+ err = -ENOMEM;
+ goto exit;
+ }
+
+ data->client = client;
+ i2c_set_clientdata(client, data);
+
+ /* Reset the device (sets the read_ptr to status) */
+ if (ds2482_send_cmd(data, DS2482_CMD_RESET) < 0) {
+ dev_warn(&client->dev, "DS2482 reset failed.\n");
+ 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(client);
+ if (temp1 != (DS2482_REG_STS_LL | DS2482_REG_STS_RST)) {
+ dev_warn(&client->dev, "DS2482 reset status "
+ "0x%02X - not a DS2482\n", 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,
+ ds2482_calculate_config(0x00));
+
+ mutex_init(&data->access_lock);
+
+ /* 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;
+ data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;
+
+ 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:
+ 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_remove(struct i2c_client *client)
+{
+ struct ds2482_data *data = i2c_get_clientdata(client);
+ int 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);
+ }
+
+ /* Free the memory */
+ kfree(data);
+ return 0;
+}
+
+module_i2c_driver(ds2482_driver);
+
+MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
+MODULE_DESCRIPTION("DS2482 driver");
+MODULE_LICENSE("GPL");
Code Review / kvmfornfv.git / blobdiff