129 lines
4.5 KiB
C
129 lines
4.5 KiB
C
/* i2c-core.c - a device driver for the iic-bus interface */
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/* ------------------------------------------------------------------------- */
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/* Copyright (C) 1995-99 Simon G. Vogl
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* ------------------------------------------------------------------------- */
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/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi>.
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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 <khali@linux-fr.org> */
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#include <types.h>
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#include <list.h>
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#include <errno.h>
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#include <linux/i2c.h>
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#include <syscall.h>
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/**
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* i2c_transfer - execute a single or combined I2C message
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* @adap: Handle to I2C bus
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* @msgs: One or more messages to execute before STOP is issued to
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* terminate the operation; each message begins with a START.
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* @num: Number of messages to be executed.
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*
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* Returns negative errno, else the number of messages executed.
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*
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* Note that there is no requirement that each message be sent to
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* the same slave address, although that is the most common model.
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*/
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int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
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{
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unsigned long orig_jiffies;
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int ret, try;
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/* REVISIT the fault reporting model here is weak:
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*
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* - When we get an error after receiving N bytes from a slave,
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* there is no way to report "N".
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*
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* - When we get a NAK after transmitting N bytes to a slave,
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* there is no way to report "N" ... or to let the master
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* continue executing the rest of this combined message, if
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* that's the appropriate response.
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*
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* - When for example "num" is two and we successfully complete
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* the first message but get an error part way through the
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* second, it's unclear whether that should be reported as
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* one (discarding status on the second message) or errno
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* (discarding status on the first one).
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*/
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if (adap->algo->master_xfer) {
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/* Retry automatically on arbitration loss */
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orig_jiffies = 0;
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for (ret = 0, try = 0; try <= adap->retries; try++) {
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ret = adap->algo->master_xfer(adap, msgs, num);
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if (ret != -EAGAIN)
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break;
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// if (time_after(jiffies, orig_jiffies + adap->timeout))
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// break;
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delay(1);
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}
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// mutex_unlock(&adap->bus_lock);
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return ret;
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} else {
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// dev_dbg(&adap->dev, "I2C level transfers not supported\n");
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return -EOPNOTSUPP;
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}
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}
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EXPORT_SYMBOL(i2c_transfer);
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/**
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* i2c_new_device - instantiate an i2c device
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* @adap: the adapter managing the device
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* @info: describes one I2C device; bus_num is ignored
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* Context: can sleep
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*
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* Create an i2c device. Binding is handled through driver model
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* probe()/remove() methods. A driver may be bound to this device when we
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* return from this function, or any later moment (e.g. maybe hotplugging will
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* load the driver module). This call is not appropriate for use by mainboard
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* initialization logic, which usually runs during an arch_initcall() long
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* before any i2c_adapter could exist.
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*
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* This returns the new i2c client, which may be saved for later use with
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* i2c_unregister_device(); or NULL to indicate an error.
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*/
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struct i2c_client *
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i2c_new_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
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{
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struct i2c_client *client;
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int status;
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client = kzalloc(sizeof *client, GFP_KERNEL);
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if (!client)
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return NULL;
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client->adapter = adap;
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client->flags = info->flags;
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client->addr = info->addr;
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client->irq = info->irq;
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strlcpy(client->name, info->type, sizeof(client->name));
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return client;
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}
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