384 lines
10 KiB
C
384 lines
10 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., 51 Franklin Street, Fifth Floor, Boston,
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MA 02110-1301 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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Mux support by Rodolfo Giometti <giometti@enneenne.com> and
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Michael Lawnick <michael.lawnick.ext@nsn.com> */
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/spinlock.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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#include <linux/jiffies.h>
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#if 0
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static ssize_t
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show_modalias(struct device *dev, struct device_attribute *attr, char *buf)
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{
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struct i2c_client *client = to_i2c_client(dev);
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return sprintf(buf, "%s%s\n", I2C_MODULE_PREFIX, client->name);
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}
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static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
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static DEVICE_ATTR(modalias, S_IRUGO, show_modalias, NULL);
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static struct attribute *i2c_dev_attrs[] = {
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&dev_attr_name.attr,
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/* modalias helps coldplug: modprobe $(cat .../modalias) */
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&dev_attr_modalias.attr,
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NULL
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};
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static struct attribute_group i2c_dev_attr_group = {
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.attrs = i2c_dev_attrs,
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};
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static const struct attribute_group *i2c_dev_attr_groups[] = {
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&i2c_dev_attr_group,
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NULL
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};
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static const struct dev_pm_ops i2c_device_pm_ops = {
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.suspend = i2c_device_pm_suspend,
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.resume = i2c_device_pm_resume,
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.freeze = i2c_device_pm_freeze,
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.thaw = i2c_device_pm_thaw,
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.poweroff = i2c_device_pm_poweroff,
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.restore = i2c_device_pm_restore,
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SET_RUNTIME_PM_OPS(
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pm_generic_runtime_suspend,
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pm_generic_runtime_resume,
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NULL
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)
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};
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struct bus_type i2c_bus_type = {
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.name = "i2c",
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.match = i2c_device_match,
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.probe = i2c_device_probe,
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.remove = i2c_device_remove,
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.shutdown = i2c_device_shutdown,
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.pm = &i2c_device_pm_ops,
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};
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EXPORT_SYMBOL_GPL(i2c_bus_type);
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static struct device_type i2c_client_type = {
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.groups = i2c_dev_attr_groups,
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.uevent = i2c_device_uevent,
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.release = i2c_client_dev_release,
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};
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/**
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* i2c_verify_client - return parameter as i2c_client, or NULL
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* @dev: device, probably from some driver model iterator
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*
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* When traversing the driver model tree, perhaps using driver model
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* iterators like @device_for_each_child(), you can't assume very much
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* about the nodes you find. Use this function to avoid oopses caused
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* by wrongly treating some non-I2C device as an i2c_client.
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*/
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struct i2c_client *i2c_verify_client(struct device *dev)
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{
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return (dev->type == &i2c_client_type)
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? to_i2c_client(dev)
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: NULL;
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}
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EXPORT_SYMBOL(i2c_verify_client);
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/* This is a permissive address validity check, I2C address map constraints
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* are purposely not enforced, except for the general call address. */
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static int i2c_check_client_addr_validity(const struct i2c_client *client)
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{
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if (client->flags & I2C_CLIENT_TEN) {
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/* 10-bit address, all values are valid */
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if (client->addr > 0x3ff)
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return -EINVAL;
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} else {
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/* 7-bit address, reject the general call address */
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if (client->addr == 0x00 || client->addr > 0x7f)
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return -EINVAL;
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}
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return 0;
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}
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/* And this is a strict address validity check, used when probing. If a
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* device uses a reserved address, then it shouldn't be probed. 7-bit
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* addressing is assumed, 10-bit address devices are rare and should be
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* explicitly enumerated. */
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static int i2c_check_addr_validity(unsigned short addr)
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{
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/*
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* Reserved addresses per I2C specification:
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* 0x00 General call address / START byte
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* 0x01 CBUS address
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* 0x02 Reserved for different bus format
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* 0x03 Reserved for future purposes
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* 0x04-0x07 Hs-mode master code
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* 0x78-0x7b 10-bit slave addressing
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* 0x7c-0x7f Reserved for future purposes
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*/
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if (addr < 0x08 || addr > 0x77)
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return -EINVAL;
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return 0;
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}
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static int __i2c_check_addr_busy(struct device *dev, void *addrp)
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{
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struct i2c_client *client = i2c_verify_client(dev);
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int addr = *(int *)addrp;
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if (client && client->addr == addr)
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return -EBUSY;
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return 0;
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}
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/* walk up mux tree */
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static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
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{
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struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
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int result;
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result = device_for_each_child(&adapter->dev, &addr,
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__i2c_check_addr_busy);
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if (!result && parent)
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result = i2c_check_mux_parents(parent, addr);
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return result;
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}
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/* recurse down mux tree */
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static int i2c_check_mux_children(struct device *dev, void *addrp)
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{
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int result;
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if (dev->type == &i2c_adapter_type)
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result = device_for_each_child(dev, addrp,
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i2c_check_mux_children);
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else
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result = __i2c_check_addr_busy(dev, addrp);
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return result;
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}
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static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
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{
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struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
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int result = 0;
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if (parent)
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result = i2c_check_mux_parents(parent, addr);
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if (!result)
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result = device_for_each_child(&adapter->dev, &addr,
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i2c_check_mux_children);
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return result;
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}
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/**
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* i2c_lock_adapter - Get exclusive access to an I2C bus segment
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* @adapter: Target I2C bus segment
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*/
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void i2c_lock_adapter(struct i2c_adapter *adapter)
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{
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struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
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if (parent)
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i2c_lock_adapter(parent);
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else
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rt_mutex_lock(&adapter->bus_lock);
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}
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EXPORT_SYMBOL_GPL(i2c_lock_adapter);
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/**
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* i2c_trylock_adapter - Try to get exclusive access to an I2C bus segment
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* @adapter: Target I2C bus segment
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*/
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static int i2c_trylock_adapter(struct i2c_adapter *adapter)
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{
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struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
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if (parent)
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return i2c_trylock_adapter(parent);
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else
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return rt_mutex_trylock(&adapter->bus_lock);
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}
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/**
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* i2c_unlock_adapter - Release exclusive access to an I2C bus segment
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* @adapter: Target I2C bus segment
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*/
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void i2c_unlock_adapter(struct i2c_adapter *adapter)
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{
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struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
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if (parent)
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i2c_unlock_adapter(parent);
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else
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rt_mutex_unlock(&adapter->bus_lock);
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}
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EXPORT_SYMBOL_GPL(i2c_unlock_adapter);
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#endif
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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 = GetTimerTicks();
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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(GetTimerTicks(), 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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dbgprintf("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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