// SPDX-License-Identifier: GPL-2.0-only /* * ds2482.c - provides i2c to w1-master bridge(s) * Copyright (C) 2005 Ben Gardner <[email protected]> * * 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 */ #include <linux/module.h> #include <linux/init.h> #include <linux/slab.h> #include <linux/i2c.h> #include <linux/delay.h> #include <linux/w1.h> /* * Allow the active pullup to be disabled, default is enabled. * * Note from the DS2482 datasheet: * The APU bit controls whether an active pullup (controlled slew-rate * transistor) or a passive pullup (Rwpu resistor) will be used to drive * a 1-Wire line from low to high. When APU = 0, active pullup is disabled * (resistor mode). Active Pullup should always be selected unless there is * only a single slave on the 1-Wire line. */ static int ds2482_active_pullup = …; module_param_named(active_pullup, ds2482_active_pullup, int, 0644); MODULE_PARM_DESC(…) …; /* extra configurations - e.g. 1WS */ static int extra_config; module_param(extra_config, int, 0644); MODULE_PARM_DESC(…) …; /* * 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 … #define DS2482_CMD_SET_READ_PTR … #define DS2482_CMD_CHANNEL_SELECT … #define DS2482_CMD_WRITE_CONFIG … #define DS2482_CMD_1WIRE_RESET … #define DS2482_CMD_1WIRE_SINGLE_BIT … #define DS2482_CMD_1WIRE_WRITE_BYTE … #define DS2482_CMD_1WIRE_READ_BYTE … /* Note to read the byte, Set the ReadPtr to Data then read (any addr) */ #define DS2482_CMD_1WIRE_TRIPLET … /* Values for DS2482_CMD_SET_READ_PTR */ #define DS2482_PTR_CODE_STATUS … #define DS2482_PTR_CODE_DATA … #define DS2482_PTR_CODE_CHANNEL … #define DS2482_PTR_CODE_CONFIG … /* * 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 … #define DS2482_REG_CFG_SPU … #define DS2482_REG_CFG_PPM … #define DS2482_REG_CFG_APU … /* * 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] = …; static const u8 ds2482_chan_rd[8] = …; /* * Status Register bit definitions (read only) */ #define DS2482_REG_STS_DIR … #define DS2482_REG_STS_TSB … #define DS2482_REG_STS_SBR … #define DS2482_REG_STS_RST … #define DS2482_REG_STS_LL … #define DS2482_REG_STS_SD … #define DS2482_REG_STS_PPD … #define DS2482_REG_STS_1WB … /* * Client data (each client gets its own) */ struct ds2482_data; struct ds2482_w1_chan { … }; struct ds2482_data { … }; /** * ds2482_calculate_config - Helper to calculate values for configuration register * @conf: the raw config value * Return: the value w/ complements that can be written to register */ static inline u8 ds2482_calculate_config(u8 conf) { … } /** * ds2482_select_register - Sets the read pointer. * @pdev: The ds2482 client pointer * @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) { … } /** * ds2482_send_cmd - Sends a command without a parameter * @pdev: The ds2482 client pointer * @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) { … } /** * ds2482_send_cmd_data - Sends a command with a parameter * @pdev: The ds2482 client pointer * @cmd: DS2482_CMD_WRITE_CONFIG, * DS2482_CMD_1WIRE_SINGLE_BIT, * DS2482_CMD_1WIRE_WRITE_BYTE, * DS2482_CMD_1WIRE_TRIPLET * @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) { … } /* * 1-Wire interface code */ #define DS2482_WAIT_IDLE_TIMEOUT … /** * ds2482_wait_1wire_idle - Waits until the 1-wire interface is idle (not busy) * * @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) { … } /** * ds2482_set_channel - Selects a w1 channel. * The 1-wire interface must be idle before calling this function. * * @pdev: The ds2482 client pointer * @channel: 0-7 * Return: -1 (failure) or 0 (success) */ static int ds2482_set_channel(struct ds2482_data *pdev, u8 channel) { … } /** * ds2482_w1_touch_bit - Performs the touch-bit function, which writes a 0 or 1 and reads the level. * * @data: The ds2482 channel pointer * @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) { … } /** * ds2482_w1_triplet - 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 * * @data: The ds2482 channel pointer * @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) { … } /** * ds2482_w1_write_byte - Performs the write byte function. * * @data: The ds2482 channel pointer * @byte: The value to write */ static void ds2482_w1_write_byte(void *data, u8 byte) { … } /** * ds2482_w1_read_byte - Performs the read byte function. * * @data: The ds2482 channel pointer * Return: The value read */ static u8 ds2482_w1_read_byte(void *data) { … } /** * ds2482_w1_reset_bus - Sends a reset on the 1-wire interface * * @data: The ds2482 channel pointer * Return: 0=Device present, 1=No device present or error */ static u8 ds2482_w1_reset_bus(void *data) { … } static u8 ds2482_w1_set_pullup(void *data, int delay) { … } static int ds2482_probe(struct i2c_client *client) { … } static void ds2482_remove(struct i2c_client *client) { … } /* * Driver data (common to all clients) */ static const struct i2c_device_id ds2482_id[] = …; MODULE_DEVICE_TABLE(i2c, ds2482_id); static struct i2c_driver ds2482_driver = …; module_i2c_driver(…) …; MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …;
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