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(Dan) Original version of chip driver for Philips PCF8574 I2C bus expander.
git-svn-id: http://lm-sensors.org/svn/lm-sensors/trunk@889 7894878c-1315-0410-8ee3-d5d059ff63e0
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/*
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pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware
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monitoring
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Copyright (c) 2000 Frodo Looijaard <frodol@dds.nl>,
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Philip Edelbrock <phil@netroedge.com>,
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Dan Eaton <dan.eaton@rocketlogix.com>
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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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/* A few notes about the PCF8574:
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* The PCF8574 is an 8-bit I/O expander for the I2C bus produced by
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Philips Semiconductors. It is designed to provide a byte I2C
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interface to up to 8 separate devices.
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* The PCF8574 appears as a very simple SMBus device which can be
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read from or written to with SMBUS byte read/write accesses.
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* Because of the general purpose nature of this device, it will most
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likely be necessary to customize the /proc interface to suit the
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specific application.
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--Dan
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*/
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#include <linux/version.h>
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#include <linux/module.h>
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#include <linux/malloc.h>
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#include <linux/i2c.h>
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#include "sensors.h"
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#include "i2c-isa.h"
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#include "version.h"
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#include <linux/init.h>
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#if (LINUX_VERSION_CODE < KERNEL_VERSION(2,3,1))
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#define init_MUTEX(s) do { *(s) = MUTEX; } while(0)
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#endif
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#if LINUX_VERSION_CODE < KERNEL_VERSION(2,3,13)
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#define THIS_MODULE NULL
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#endif
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/* Addresses to scan */
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static unsigned short normal_i2c[] = { SENSORS_I2C_END };
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static unsigned short normal_i2c_range[] = { 0x20, 0x27, SENSORS_I2C_END };
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static unsigned int normal_isa[] = { SENSORS_ISA_END };
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static unsigned int normal_isa_range[] = { SENSORS_ISA_END };
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/* Insmod parameters */
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SENSORS_INSMOD_1(pcf8574);
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/* The PCF8574 registers */
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/* (No registers. [Wow! This thing is SIMPLE!] ) */
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/* Initial values */
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#define PCF8574_INIT 0 /* Both off */
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/* Each client has this additional data */
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struct pcf8574_data {
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int sysctl_id;
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struct semaphore update_lock;
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char valid; /* !=0 if following fields are valid */
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unsigned long last_updated; /* In jiffies */
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u8 status; /* Register values */
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};
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#ifdef MODULE
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extern int init_module(void);
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extern int cleanup_module(void);
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#endif /* MODULE */
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#ifdef MODULE
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static
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#else
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extern
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#endif
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int __init sensors_pcf8574_init(void);
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static int __init pcf8574_cleanup(void);
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static int pcf8574_attach_adapter(struct i2c_adapter *adapter);
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static int pcf8574_detect(struct i2c_adapter *adapter, int address,
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unsigned short flags, int kind);
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static int pcf8574_detach_client(struct i2c_client *client);
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static int pcf8574_command(struct i2c_client *client, unsigned int cmd,
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void *arg);
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static void pcf8574_inc_use(struct i2c_client *client);
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static void pcf8574_dec_use(struct i2c_client *client);
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static void pcf8574_status(struct i2c_client *client, int operation,
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int ctl_name, int *nrels_mag, long *results);
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static void pcf8574_update_client(struct i2c_client *client);
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/* This is the driver that will be inserted */
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static struct i2c_driver pcf8574_driver = {
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/* name */ "PCF8574 sensor chip driver",
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/* id */ I2C_DRIVERID_PCF8574,
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/* flags */ I2C_DF_NOTIFY,
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/* attach_adapter */ &pcf8574_attach_adapter,
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/* detach_client */ &pcf8574_detach_client,
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/* command */ &pcf8574_command,
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/* inc_use */ &pcf8574_inc_use,
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/* dec_use */ &pcf8574_dec_use
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};
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/* These files are created for each detected PCF8574. This is just a template;
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though at first sight, you might think we could use a statically
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allocated list, we need some way to get back to the parent - which
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is done through one of the 'extra' fields which are initialized
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when a new copy is allocated. */
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static ctl_table pcf8574_dir_table_template[] = {
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{PCF8574_SYSCTL_STAT, "status", NULL, 0, 0644, NULL, &sensors_proc_real,
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&sensors_sysctl_real, NULL, &pcf8574_status},
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{0}
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};
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/* Used by init/cleanup */
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static int __initdata pcf8574_initialized = 0;
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/* I choose here for semi-static PCF8574 allocation. Complete dynamic
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allocation could also be used; the code needed for this would probably
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take more memory than the datastructure takes now. */
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static int pcf8574_id = 0;
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int pcf8574_attach_adapter(struct i2c_adapter *adapter)
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{
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return sensors_detect(adapter, &addr_data, pcf8574_detect);
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}
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/* This function is called by sensors_detect */
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int pcf8574_detect(struct i2c_adapter *adapter, int address,
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unsigned short flags, int kind)
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{
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int i;
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struct i2c_client *new_client;
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struct pcf8574_data *data;
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int err = 0;
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const char *type_name, *client_name;
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/* Make sure we aren't probing the ISA bus!! This is just a safety check
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at this moment; sensors_detect really won't call us. */
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#ifdef DEBUG
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if (i2c_is_isa_adapter(adapter)) {
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printk
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("pcf8574.o: pcf8574_detect called for an ISA bus adapter?!?\n");
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return 0;
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}
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#endif
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if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE))
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goto ERROR0;
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/* OK. For now, we presume we have a valid client. We now create the
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client structure, even though we cannot fill it completely yet.
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But it allows us to access pcf8574_{read,write}_value. */
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if (!(new_client = kmalloc(sizeof(struct i2c_client) +
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sizeof(struct pcf8574_data),
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GFP_KERNEL))) {
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err = -ENOMEM;
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goto ERROR0;
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}
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data = (struct pcf8574_data *) (new_client + 1);
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new_client->addr = address;
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new_client->data = data;
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new_client->adapter = adapter;
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new_client->driver = &pcf8574_driver;
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new_client->flags = 0;
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/* Now, we would do the remaining detection. But the PCF8574 is plainly
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impossible to detect! Stupid chip. */
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/* Determine the chip type - only one kind supported! */
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if (kind <= 0)
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kind = pcf8574;
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if (kind == pcf8574) {
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type_name = "pcf8574";
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client_name = "PCF8574 chip";
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} else {
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#ifdef DEBUG
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printk("pcf8574.o: Internal error: unknown kind (%d)?!?",
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kind);
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#endif
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goto ERROR1;
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}
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/* Fill in the remaining client fields and put it into the global list */
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strcpy(new_client->name, client_name);
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new_client->id = pcf8574_id++;
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data->valid = 0;
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init_MUTEX(&data->update_lock);
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/* Tell the I2C layer a new client has arrived */
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if ((err = i2c_attach_client(new_client)))
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goto ERROR3;
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/* Register a new directory entry with module sensors */
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if ((i = sensors_register_entry(new_client, type_name,
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pcf8574_dir_table_template,
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THIS_MODULE)) < 0) {
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err = i;
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goto ERROR4;
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}
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data->sysctl_id = i;
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return 0;
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/* OK, this is not exactly good programming practice, usually. But it is
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very code-efficient in this case. */
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ERROR4:
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i2c_detach_client(new_client);
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ERROR3:
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ERROR1:
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kfree(new_client);
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ERROR0:
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return err;
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}
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int pcf8574_detach_client(struct i2c_client *client)
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{
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int err;
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sensors_deregister_entry(((struct pcf8574_data *) (client->data))->
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sysctl_id);
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if ((err = i2c_detach_client(client))) {
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printk
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("pcf8574.o: Client deregistration failed, client not detached.\n");
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return err;
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}
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kfree(client);
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return 0;
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}
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/* No commands defined yet */
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int pcf8574_command(struct i2c_client *client, unsigned int cmd, void *arg)
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{
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return 0;
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}
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/* Nothing here yet */
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void pcf8574_inc_use(struct i2c_client *client)
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{
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#ifdef MODULE
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MOD_INC_USE_COUNT;
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#endif
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}
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/* Nothing here yet */
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void pcf8574_dec_use(struct i2c_client *client)
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{
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#ifdef MODULE
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MOD_DEC_USE_COUNT;
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#endif
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}
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void pcf8574_update_client(struct i2c_client *client)
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{
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struct pcf8574_data *data = client->data;
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down(&data->update_lock);
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if ((jiffies - data->last_updated > HZ + HZ / 2) ||
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(jiffies < data->last_updated) || !data->valid) {
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#ifdef DEBUG
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printk("Starting pcf8574 update\n");
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#endif
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data->status = i2c_smbus_read_byte(client);
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data->last_updated = jiffies;
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data->valid = 1;
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}
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up(&data->update_lock);
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}
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void pcf8574_status(struct i2c_client *client, int operation,
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int ctl_name, int *nrels_mag, long *results)
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{
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u8 tmpstatus;
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struct pcf8574_data *data = client->data;
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if (operation == SENSORS_PROC_REAL_INFO)
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*nrels_mag = 0;
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else if (operation == SENSORS_PROC_REAL_READ) {
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pcf8574_update_client(client);
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tmpstatus = data->status;
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tmpstatus = (tmpstatus & 0xf0) >> 4;
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data->status &= 0x0f;
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results[0] = tmpstatus;
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results[1] = data->status;
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*nrels_mag = 2;
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} else if (operation == SENSORS_PROC_REAL_WRITE) {
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if (*nrels_mag >= 1) {
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data->status = (data->status & 2) | results[0];
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i2c_smbus_write_byte(client, data->status);
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}
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}
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}
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int __init sensors_pcf8574_init(void)
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{
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int res;
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printk("pcf8574.o version %s (%s)\n", LM_VERSION, LM_DATE);
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pcf8574_initialized = 0;
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if ((res = i2c_add_driver(&pcf8574_driver))) {
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printk
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("pcf8574.o: Driver registration failed, module not inserted.\n");
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pcf8574_cleanup();
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return res;
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}
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pcf8574_initialized++;
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return 0;
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}
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int __init pcf8574_cleanup(void)
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{
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int res;
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if (pcf8574_initialized >= 1) {
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if ((res = i2c_del_driver(&pcf8574_driver))) {
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printk
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("pcf8574.o: Driver deregistration failed, module not removed.\n");
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return res;
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}
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pcf8574_initialized--;
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}
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return 0;
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}
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EXPORT_NO_SYMBOLS;
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#ifdef MODULE
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MODULE_AUTHOR
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("Frodo Looijaard <frodol@dds.nl>, Philip Edelbrock <phil@netroedge.com and Dan Eaton <dan.eaton@rocketlogix.com>");
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MODULE_DESCRIPTION("PCF8574 driver");
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int init_module(void)
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{
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return sensors_pcf8574_init();
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}
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int cleanup_module(void)
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{
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return pcf8574_cleanup();
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}
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#endif /* MODULE */
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