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![Phil Reid](/assets/img/avatar_default.png)
This commit adds of_i2c_setup_smbus_alert which allows the smbalert driver to be attached to an i2c adapter via the device tree. Signed-off-by: Phil Reid <preid@electromag.com.au> Acked-by: Rob Herring <robh@kernel.org> Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
649 lines
19 KiB
C
649 lines
19 KiB
C
/*
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* Linux I2C core SMBus and SMBus emulation code
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*
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* This file contains the SMBus functions which are always included in the I2C
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* core because they can be emulated via I2C. SMBus specific extensions
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* (e.g. smbalert) are handled in a seperate i2c-smbus module.
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*
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* All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
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* SMBus 2.0 support by Mark Studebaker <mdsxyz123@yahoo.com> and
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* Jean Delvare <jdelvare@suse.de>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*/
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/i2c-smbus.h>
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#define CREATE_TRACE_POINTS
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#include <trace/events/smbus.h>
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/* The SMBus parts */
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#define POLY (0x1070U << 3)
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static u8 crc8(u16 data)
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{
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int i;
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for (i = 0; i < 8; i++) {
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if (data & 0x8000)
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data = data ^ POLY;
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data = data << 1;
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}
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return (u8)(data >> 8);
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}
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/* Incremental CRC8 over count bytes in the array pointed to by p */
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static u8 i2c_smbus_pec(u8 crc, u8 *p, size_t count)
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{
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int i;
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for (i = 0; i < count; i++)
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crc = crc8((crc ^ p[i]) << 8);
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return crc;
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}
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/* Assume a 7-bit address, which is reasonable for SMBus */
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static u8 i2c_smbus_msg_pec(u8 pec, struct i2c_msg *msg)
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{
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/* The address will be sent first */
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u8 addr = i2c_8bit_addr_from_msg(msg);
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pec = i2c_smbus_pec(pec, &addr, 1);
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/* The data buffer follows */
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return i2c_smbus_pec(pec, msg->buf, msg->len);
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}
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/* Used for write only transactions */
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static inline void i2c_smbus_add_pec(struct i2c_msg *msg)
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{
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msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);
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msg->len++;
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}
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/* Return <0 on CRC error
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If there was a write before this read (most cases) we need to take the
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partial CRC from the write part into account.
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Note that this function does modify the message (we need to decrease the
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message length to hide the CRC byte from the caller). */
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static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
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{
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u8 rpec = msg->buf[--msg->len];
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cpec = i2c_smbus_msg_pec(cpec, msg);
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if (rpec != cpec) {
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pr_debug("Bad PEC 0x%02x vs. 0x%02x\n",
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rpec, cpec);
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return -EBADMSG;
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}
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return 0;
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}
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/**
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* i2c_smbus_read_byte - SMBus "receive byte" protocol
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* @client: Handle to slave device
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*
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* This executes the SMBus "receive byte" protocol, returning negative errno
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* else the byte received from the device.
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*/
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s32 i2c_smbus_read_byte(const struct i2c_client *client)
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{
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union i2c_smbus_data data;
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int status;
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status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_READ, 0,
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I2C_SMBUS_BYTE, &data);
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return (status < 0) ? status : data.byte;
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}
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EXPORT_SYMBOL(i2c_smbus_read_byte);
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/**
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* i2c_smbus_write_byte - SMBus "send byte" protocol
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* @client: Handle to slave device
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* @value: Byte to be sent
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*
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* This executes the SMBus "send byte" protocol, returning negative errno
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* else zero on success.
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*/
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s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
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{
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return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
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}
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EXPORT_SYMBOL(i2c_smbus_write_byte);
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/**
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* i2c_smbus_read_byte_data - SMBus "read byte" protocol
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* @client: Handle to slave device
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* @command: Byte interpreted by slave
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*
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* This executes the SMBus "read byte" protocol, returning negative errno
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* else a data byte received from the device.
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*/
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s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
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{
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union i2c_smbus_data data;
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int status;
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status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_READ, command,
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I2C_SMBUS_BYTE_DATA, &data);
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return (status < 0) ? status : data.byte;
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}
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EXPORT_SYMBOL(i2c_smbus_read_byte_data);
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/**
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* i2c_smbus_write_byte_data - SMBus "write byte" protocol
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* @client: Handle to slave device
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* @command: Byte interpreted by slave
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* @value: Byte being written
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*
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* This executes the SMBus "write byte" protocol, returning negative errno
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* else zero on success.
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*/
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s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
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u8 value)
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{
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union i2c_smbus_data data;
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data.byte = value;
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return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_WRITE, command,
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I2C_SMBUS_BYTE_DATA, &data);
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}
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EXPORT_SYMBOL(i2c_smbus_write_byte_data);
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/**
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* i2c_smbus_read_word_data - SMBus "read word" protocol
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* @client: Handle to slave device
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* @command: Byte interpreted by slave
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*
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* This executes the SMBus "read word" protocol, returning negative errno
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* else a 16-bit unsigned "word" received from the device.
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*/
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s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
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{
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union i2c_smbus_data data;
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int status;
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status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_READ, command,
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I2C_SMBUS_WORD_DATA, &data);
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return (status < 0) ? status : data.word;
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}
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EXPORT_SYMBOL(i2c_smbus_read_word_data);
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/**
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* i2c_smbus_write_word_data - SMBus "write word" protocol
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* @client: Handle to slave device
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* @command: Byte interpreted by slave
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* @value: 16-bit "word" being written
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*
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* This executes the SMBus "write word" protocol, returning negative errno
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* else zero on success.
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*/
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s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
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u16 value)
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{
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union i2c_smbus_data data;
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data.word = value;
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return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_WRITE, command,
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I2C_SMBUS_WORD_DATA, &data);
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}
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EXPORT_SYMBOL(i2c_smbus_write_word_data);
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/**
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* i2c_smbus_read_block_data - SMBus "block read" protocol
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* @client: Handle to slave device
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* @command: Byte interpreted by slave
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* @values: Byte array into which data will be read; big enough to hold
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* the data returned by the slave. SMBus allows at most 32 bytes.
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*
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* This executes the SMBus "block read" protocol, returning negative errno
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* else the number of data bytes in the slave's response.
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*
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* Note that using this function requires that the client's adapter support
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* the I2C_FUNC_SMBUS_READ_BLOCK_DATA functionality. Not all adapter drivers
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* support this; its emulation through I2C messaging relies on a specific
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* mechanism (I2C_M_RECV_LEN) which may not be implemented.
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*/
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s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
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u8 *values)
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{
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union i2c_smbus_data data;
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int status;
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status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_READ, command,
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I2C_SMBUS_BLOCK_DATA, &data);
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if (status)
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return status;
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memcpy(values, &data.block[1], data.block[0]);
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return data.block[0];
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}
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EXPORT_SYMBOL(i2c_smbus_read_block_data);
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/**
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* i2c_smbus_write_block_data - SMBus "block write" protocol
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* @client: Handle to slave device
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* @command: Byte interpreted by slave
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* @length: Size of data block; SMBus allows at most 32 bytes
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* @values: Byte array which will be written.
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*
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* This executes the SMBus "block write" protocol, returning negative errno
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* else zero on success.
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*/
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s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
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u8 length, const u8 *values)
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{
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union i2c_smbus_data data;
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if (length > I2C_SMBUS_BLOCK_MAX)
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length = I2C_SMBUS_BLOCK_MAX;
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data.block[0] = length;
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memcpy(&data.block[1], values, length);
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return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_WRITE, command,
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I2C_SMBUS_BLOCK_DATA, &data);
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}
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EXPORT_SYMBOL(i2c_smbus_write_block_data);
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/* Returns the number of read bytes */
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s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
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u8 length, u8 *values)
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{
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union i2c_smbus_data data;
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int status;
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if (length > I2C_SMBUS_BLOCK_MAX)
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length = I2C_SMBUS_BLOCK_MAX;
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data.block[0] = length;
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status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_READ, command,
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I2C_SMBUS_I2C_BLOCK_DATA, &data);
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if (status < 0)
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return status;
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memcpy(values, &data.block[1], data.block[0]);
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return data.block[0];
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}
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EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
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s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
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u8 length, const u8 *values)
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{
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union i2c_smbus_data data;
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if (length > I2C_SMBUS_BLOCK_MAX)
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length = I2C_SMBUS_BLOCK_MAX;
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data.block[0] = length;
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memcpy(data.block + 1, values, length);
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return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
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I2C_SMBUS_WRITE, command,
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I2C_SMBUS_I2C_BLOCK_DATA, &data);
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}
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EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);
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/* Simulate a SMBus command using the i2c protocol
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No checking of parameters is done! */
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static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
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unsigned short flags,
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char read_write, u8 command, int size,
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union i2c_smbus_data *data)
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{
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/* So we need to generate a series of msgs. In the case of writing, we
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need to use only one message; when reading, we need two. We initialize
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most things with sane defaults, to keep the code below somewhat
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simpler. */
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unsigned char msgbuf0[I2C_SMBUS_BLOCK_MAX+3];
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unsigned char msgbuf1[I2C_SMBUS_BLOCK_MAX+2];
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int num = read_write == I2C_SMBUS_READ ? 2 : 1;
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int i;
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u8 partial_pec = 0;
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int status;
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struct i2c_msg msg[2] = {
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{
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.addr = addr,
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.flags = flags,
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.len = 1,
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.buf = msgbuf0,
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}, {
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.addr = addr,
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.flags = flags | I2C_M_RD,
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.len = 0,
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.buf = msgbuf1,
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},
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};
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msgbuf0[0] = command;
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switch (size) {
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case I2C_SMBUS_QUICK:
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msg[0].len = 0;
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/* Special case: The read/write field is used as data */
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msg[0].flags = flags | (read_write == I2C_SMBUS_READ ?
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I2C_M_RD : 0);
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num = 1;
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break;
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case I2C_SMBUS_BYTE:
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if (read_write == I2C_SMBUS_READ) {
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/* Special case: only a read! */
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msg[0].flags = I2C_M_RD | flags;
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num = 1;
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}
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break;
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case I2C_SMBUS_BYTE_DATA:
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if (read_write == I2C_SMBUS_READ)
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msg[1].len = 1;
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else {
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msg[0].len = 2;
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msgbuf0[1] = data->byte;
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}
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break;
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case I2C_SMBUS_WORD_DATA:
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if (read_write == I2C_SMBUS_READ)
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msg[1].len = 2;
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else {
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msg[0].len = 3;
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msgbuf0[1] = data->word & 0xff;
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msgbuf0[2] = data->word >> 8;
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}
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break;
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case I2C_SMBUS_PROC_CALL:
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num = 2; /* Special case */
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read_write = I2C_SMBUS_READ;
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msg[0].len = 3;
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msg[1].len = 2;
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msgbuf0[1] = data->word & 0xff;
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msgbuf0[2] = data->word >> 8;
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break;
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case I2C_SMBUS_BLOCK_DATA:
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if (read_write == I2C_SMBUS_READ) {
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msg[1].flags |= I2C_M_RECV_LEN;
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msg[1].len = 1; /* block length will be added by
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the underlying bus driver */
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} else {
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msg[0].len = data->block[0] + 2;
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if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 2) {
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dev_err(&adapter->dev,
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"Invalid block write size %d\n",
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data->block[0]);
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return -EINVAL;
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}
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for (i = 1; i < msg[0].len; i++)
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msgbuf0[i] = data->block[i-1];
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}
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break;
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case I2C_SMBUS_BLOCK_PROC_CALL:
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num = 2; /* Another special case */
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read_write = I2C_SMBUS_READ;
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if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {
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dev_err(&adapter->dev,
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"Invalid block write size %d\n",
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data->block[0]);
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return -EINVAL;
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}
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msg[0].len = data->block[0] + 2;
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for (i = 1; i < msg[0].len; i++)
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msgbuf0[i] = data->block[i-1];
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msg[1].flags |= I2C_M_RECV_LEN;
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msg[1].len = 1; /* block length will be added by
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the underlying bus driver */
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break;
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case I2C_SMBUS_I2C_BLOCK_DATA:
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if (read_write == I2C_SMBUS_READ) {
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msg[1].len = data->block[0];
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} else {
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msg[0].len = data->block[0] + 1;
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if (msg[0].len > I2C_SMBUS_BLOCK_MAX + 1) {
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dev_err(&adapter->dev,
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"Invalid block write size %d\n",
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data->block[0]);
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return -EINVAL;
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}
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for (i = 1; i <= data->block[0]; i++)
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msgbuf0[i] = data->block[i];
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}
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break;
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default:
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dev_err(&adapter->dev, "Unsupported transaction %d\n", size);
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return -EOPNOTSUPP;
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}
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i = ((flags & I2C_CLIENT_PEC) && size != I2C_SMBUS_QUICK
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&& size != I2C_SMBUS_I2C_BLOCK_DATA);
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if (i) {
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/* Compute PEC if first message is a write */
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if (!(msg[0].flags & I2C_M_RD)) {
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if (num == 1) /* Write only */
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i2c_smbus_add_pec(&msg[0]);
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else /* Write followed by read */
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partial_pec = i2c_smbus_msg_pec(0, &msg[0]);
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}
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/* Ask for PEC if last message is a read */
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if (msg[num-1].flags & I2C_M_RD)
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msg[num-1].len++;
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}
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status = i2c_transfer(adapter, msg, num);
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if (status < 0)
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return status;
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/* Check PEC if last message is a read */
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if (i && (msg[num-1].flags & I2C_M_RD)) {
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status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
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if (status < 0)
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return status;
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}
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if (read_write == I2C_SMBUS_READ)
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switch (size) {
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case I2C_SMBUS_BYTE:
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data->byte = msgbuf0[0];
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break;
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case I2C_SMBUS_BYTE_DATA:
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data->byte = msgbuf1[0];
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break;
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case I2C_SMBUS_WORD_DATA:
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case I2C_SMBUS_PROC_CALL:
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data->word = msgbuf1[0] | (msgbuf1[1] << 8);
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break;
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case I2C_SMBUS_I2C_BLOCK_DATA:
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for (i = 0; i < data->block[0]; i++)
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data->block[i+1] = msgbuf1[i];
|
|
break;
|
|
case I2C_SMBUS_BLOCK_DATA:
|
|
case I2C_SMBUS_BLOCK_PROC_CALL:
|
|
for (i = 0; i < msgbuf1[0] + 1; i++)
|
|
data->block[i] = msgbuf1[i];
|
|
break;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* i2c_smbus_xfer - execute SMBus protocol operations
|
|
* @adapter: Handle to I2C bus
|
|
* @addr: Address of SMBus slave on that bus
|
|
* @flags: I2C_CLIENT_* flags (usually zero or I2C_CLIENT_PEC)
|
|
* @read_write: I2C_SMBUS_READ or I2C_SMBUS_WRITE
|
|
* @command: Byte interpreted by slave, for protocols which use such bytes
|
|
* @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
|
|
* @data: Data to be read or written
|
|
*
|
|
* This executes an SMBus protocol operation, and returns a negative
|
|
* errno code else zero on success.
|
|
*/
|
|
s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
|
|
char read_write, u8 command, int protocol,
|
|
union i2c_smbus_data *data)
|
|
{
|
|
unsigned long orig_jiffies;
|
|
int try;
|
|
s32 res;
|
|
|
|
/* If enabled, the following two tracepoints are conditional on
|
|
* read_write and protocol.
|
|
*/
|
|
trace_smbus_write(adapter, addr, flags, read_write,
|
|
command, protocol, data);
|
|
trace_smbus_read(adapter, addr, flags, read_write,
|
|
command, protocol);
|
|
|
|
flags &= I2C_M_TEN | I2C_CLIENT_PEC | I2C_CLIENT_SCCB;
|
|
|
|
if (adapter->algo->smbus_xfer) {
|
|
i2c_lock_bus(adapter, I2C_LOCK_SEGMENT);
|
|
|
|
/* Retry automatically on arbitration loss */
|
|
orig_jiffies = jiffies;
|
|
for (res = 0, try = 0; try <= adapter->retries; try++) {
|
|
res = adapter->algo->smbus_xfer(adapter, addr, flags,
|
|
read_write, command,
|
|
protocol, data);
|
|
if (res != -EAGAIN)
|
|
break;
|
|
if (time_after(jiffies,
|
|
orig_jiffies + adapter->timeout))
|
|
break;
|
|
}
|
|
i2c_unlock_bus(adapter, I2C_LOCK_SEGMENT);
|
|
|
|
if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)
|
|
goto trace;
|
|
/*
|
|
* Fall back to i2c_smbus_xfer_emulated if the adapter doesn't
|
|
* implement native support for the SMBus operation.
|
|
*/
|
|
}
|
|
|
|
res = i2c_smbus_xfer_emulated(adapter, addr, flags, read_write,
|
|
command, protocol, data);
|
|
|
|
trace:
|
|
/* If enabled, the reply tracepoint is conditional on read_write. */
|
|
trace_smbus_reply(adapter, addr, flags, read_write,
|
|
command, protocol, data);
|
|
trace_smbus_result(adapter, addr, flags, read_write,
|
|
command, protocol, res);
|
|
|
|
return res;
|
|
}
|
|
EXPORT_SYMBOL(i2c_smbus_xfer);
|
|
|
|
/**
|
|
* i2c_smbus_read_i2c_block_data_or_emulated - read block or emulate
|
|
* @client: Handle to slave device
|
|
* @command: Byte interpreted by slave
|
|
* @length: Size of data block; SMBus allows at most I2C_SMBUS_BLOCK_MAX bytes
|
|
* @values: Byte array into which data will be read; big enough to hold
|
|
* the data returned by the slave. SMBus allows at most
|
|
* I2C_SMBUS_BLOCK_MAX bytes.
|
|
*
|
|
* This executes the SMBus "block read" protocol if supported by the adapter.
|
|
* If block read is not supported, it emulates it using either word or byte
|
|
* read protocols depending on availability.
|
|
*
|
|
* The addresses of the I2C slave device that are accessed with this function
|
|
* must be mapped to a linear region, so that a block read will have the same
|
|
* effect as a byte read. Before using this function you must double-check
|
|
* if the I2C slave does support exchanging a block transfer with a byte
|
|
* transfer.
|
|
*/
|
|
s32 i2c_smbus_read_i2c_block_data_or_emulated(const struct i2c_client *client,
|
|
u8 command, u8 length, u8 *values)
|
|
{
|
|
u8 i = 0;
|
|
int status;
|
|
|
|
if (length > I2C_SMBUS_BLOCK_MAX)
|
|
length = I2C_SMBUS_BLOCK_MAX;
|
|
|
|
if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
|
|
return i2c_smbus_read_i2c_block_data(client, command, length, values);
|
|
|
|
if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA))
|
|
return -EOPNOTSUPP;
|
|
|
|
if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) {
|
|
while ((i + 2) <= length) {
|
|
status = i2c_smbus_read_word_data(client, command + i);
|
|
if (status < 0)
|
|
return status;
|
|
values[i] = status & 0xff;
|
|
values[i + 1] = status >> 8;
|
|
i += 2;
|
|
}
|
|
}
|
|
|
|
while (i < length) {
|
|
status = i2c_smbus_read_byte_data(client, command + i);
|
|
if (status < 0)
|
|
return status;
|
|
values[i] = status;
|
|
i++;
|
|
}
|
|
|
|
return i;
|
|
}
|
|
EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data_or_emulated);
|
|
|
|
/**
|
|
* i2c_setup_smbus_alert - Setup SMBus alert support
|
|
* @adapter: the target adapter
|
|
* @setup: setup data for the SMBus alert handler
|
|
* Context: can sleep
|
|
*
|
|
* Setup handling of the SMBus alert protocol on a given I2C bus segment.
|
|
*
|
|
* Handling can be done either through our IRQ handler, or by the
|
|
* adapter (from its handler, periodic polling, or whatever).
|
|
*
|
|
* NOTE that if we manage the IRQ, we *MUST* know if it's level or
|
|
* edge triggered in order to hand it to the workqueue correctly.
|
|
* If triggering the alert seems to wedge the system, you probably
|
|
* should have said it's level triggered.
|
|
*
|
|
* This returns the ara client, which should be saved for later use with
|
|
* i2c_handle_smbus_alert() and ultimately i2c_unregister_device(); or NULL
|
|
* to indicate an error.
|
|
*/
|
|
struct i2c_client *i2c_setup_smbus_alert(struct i2c_adapter *adapter,
|
|
struct i2c_smbus_alert_setup *setup)
|
|
{
|
|
struct i2c_board_info ara_board_info = {
|
|
I2C_BOARD_INFO("smbus_alert", 0x0c),
|
|
.platform_data = setup,
|
|
};
|
|
|
|
return i2c_new_device(adapter, &ara_board_info);
|
|
}
|
|
EXPORT_SYMBOL_GPL(i2c_setup_smbus_alert);
|
|
|
|
#if IS_ENABLED(CONFIG_I2C_SMBUS) && IS_ENABLED(CONFIG_OF)
|
|
int of_i2c_setup_smbus_alert(struct i2c_adapter *adapter)
|
|
{
|
|
struct i2c_client *client;
|
|
int irq;
|
|
|
|
irq = of_property_match_string(adapter->dev.of_node, "interrupt-names",
|
|
"smbus_alert");
|
|
if (irq == -EINVAL || irq == -ENODATA)
|
|
return 0;
|
|
else if (irq < 0)
|
|
return irq;
|
|
|
|
client = i2c_setup_smbus_alert(adapter, NULL);
|
|
if (!client)
|
|
return -ENODEV;
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(of_i2c_setup_smbus_alert);
|
|
#endif
|