/* pcf8574.c - Part of lm_sensors, Linux kernel modules for hardware monitoring Copyright (c) 2000 Frodo Looijaard , Philip Edelbrock , Dan Eaton This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ /* A few notes about the PCF8574: * The PCF8574 is an 8-bit I/O expander for the I2C bus produced by Philips Semiconductors. It is designed to provide a byte I2C interface to up to 8 separate devices. * The PCF8574 appears as a very simple SMBus device which can be read from or written to with SMBUS byte read/write accesses. * Because of the general purpose nature of this device, it will most likely be necessary to customize the /proc interface to suit the specific application. --Dan */ #include #include #include #include #include #include "version.h" MODULE_LICENSE("GPL"); /* Addresses to scan */ static unsigned short normal_i2c[] = { SENSORS_I2C_END }; static unsigned short normal_i2c_range[] = { 0x20, 0x27, 0x38, 0x3f, SENSORS_I2C_END }; static unsigned int normal_isa[] = { SENSORS_ISA_END }; static unsigned int normal_isa_range[] = { SENSORS_ISA_END }; /* Insmod parameters */ SENSORS_INSMOD_2(pcf8574, pcf8574a); /* The PCF8574 registers */ /* (No registers. [Wow! This thing is SIMPLE!] ) */ /* Initial values */ #define PCF8574_INIT 255 /* All outputs on (input mode) */ /* Each client has this additional data */ struct pcf8574_data { int sysctl_id; struct semaphore update_lock; char valid; /* !=0 if following fields are valid */ unsigned long last_updated; /* In jiffies */ u8 read, write; /* Register values */ }; static int pcf8574_attach_adapter(struct i2c_adapter *adapter); static int pcf8574_detect(struct i2c_adapter *adapter, int address, unsigned short flags, int kind); static int pcf8574_detach_client(struct i2c_client *client); static void pcf8574_read(struct i2c_client *client, int operation, int ctl_name, int *nrels_mag, long *results); static void pcf8574_write(struct i2c_client *client, int operation, int ctl_name, int *nrels_mag, long *results); static void pcf8574_update_client(struct i2c_client *client); static void pcf8574_init_client(struct i2c_client *client); /* This is the driver that will be inserted */ static struct i2c_driver pcf8574_driver = { .owner = THIS_MODULE, .name = "PCF8574 sensor chip driver", .id = I2C_DRIVERID_PCF8574, .flags = I2C_DF_NOTIFY, .attach_adapter = pcf8574_attach_adapter, .detach_client = pcf8574_detach_client, }; /* -- SENSORS SYSCTL START -- */ #define PCF8574_SYSCTL_READ 1000 #define PCF8574_SYSCTL_WRITE 1001 /* -- SENSORS SYSCTL END -- */ /* These files are created for each detected PCF8574. This is just a template; though at first sight, you might think we could use a statically allocated list, we need some way to get back to the parent - which is done through one of the 'extra' fields which are initialized when a new copy is allocated. */ static ctl_table pcf8574_dir_table_template[] = { {PCF8574_SYSCTL_READ, "read", NULL, 0, 0444, NULL, &i2c_proc_real, &i2c_sysctl_real, NULL, &pcf8574_read}, {PCF8574_SYSCTL_WRITE, "write", NULL, 0, 0644, NULL, &i2c_proc_real, &i2c_sysctl_real, NULL, &pcf8574_write}, {0} }; /* I choose here for semi-static PCF8574 allocation. Complete dynamic allocation could also be used; the code needed for this would probably take more memory than the datastructure takes now. */ static int pcf8574_id = 0; static int pcf8574_attach_adapter(struct i2c_adapter *adapter) { return i2c_detect(adapter, &addr_data, pcf8574_detect); } /* This function is called by i2c_detect */ int pcf8574_detect(struct i2c_adapter *adapter, int address, unsigned short flags, int kind) { int i; struct i2c_client *new_client; struct pcf8574_data *data; int err = 0; const char *type_name, *client_name; /* Make sure we aren't probing the ISA bus!! This is just a safety check at this moment; i2c_detect really won't call us. */ #ifdef DEBUG if (i2c_is_isa_adapter(adapter)) { printk ("pcf8574.o: pcf8574_detect called for an ISA bus adapter?!?\n"); return 0; } #endif if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE)) goto ERROR0; /* OK. For now, we presume we have a valid client. We now create the client structure, even though we cannot fill it completely yet. But it allows us to access pcf8574_{read,write}_value. */ if (!(new_client = kmalloc(sizeof(struct i2c_client) + sizeof(struct pcf8574_data), GFP_KERNEL))) { err = -ENOMEM; goto ERROR0; } data = (struct pcf8574_data *) (new_client + 1); new_client->addr = address; new_client->data = data; new_client->adapter = adapter; new_client->driver = &pcf8574_driver; new_client->flags = 0; /* Now, we would do the remaining detection. But the PCF8574 is plainly impossible to detect! Stupid chip. */ /* Determine the chip type */ if (kind <= 0) { if (address >= 0x20 && address <= 0x27) kind = pcf8574; else if (address >= 0x38 && address <= 0x3f) kind = pcf8574a; else goto ERROR1; } if (kind == pcf8574) { type_name = "pcf8574"; client_name = "PCF8574 chip"; } else if (kind == pcf8574a) { type_name = "pcf8574a"; client_name = "PCF8574A chip"; } else { #ifdef DEBUG printk("pcf8574.o: Internal error: unknown kind (%d)?!?", kind); #endif goto ERROR1; } /* Fill in the remaining client fields and put it into the global list */ strcpy(new_client->name, client_name); new_client->id = pcf8574_id++; data->valid = 0; init_MUTEX(&data->update_lock); /* Tell the I2C layer a new client has arrived */ if ((err = i2c_attach_client(new_client))) goto ERROR3; /* Register a new directory entry with module sensors */ if ((i = i2c_register_entry(new_client, type_name, pcf8574_dir_table_template)) < 0) { err = i; goto ERROR4; } data->sysctl_id = i; /* Initialize the PCF8574 chip */ pcf8574_init_client(new_client); return 0; /* OK, this is not exactly good programming practice, usually. But it is very code-efficient in this case. */ ERROR4: i2c_detach_client(new_client); ERROR3: ERROR1: kfree(new_client); ERROR0: return err; } static int pcf8574_detach_client(struct i2c_client *client) { int err; i2c_deregister_entry(((struct pcf8574_data *) (client->data))-> sysctl_id); if ((err = i2c_detach_client(client))) { printk ("pcf8574.o: Client deregistration failed, client not detached.\n"); return err; } kfree(client); return 0; } /* Called when we have found a new PCF8574. */ static void pcf8574_init_client(struct i2c_client *client) { struct pcf8574_data *data = client->data; data->write = PCF8574_INIT; i2c_smbus_write_byte(client, data->write); } static void pcf8574_update_client(struct i2c_client *client) { struct pcf8574_data *data = client->data; down(&data->update_lock); if ((jiffies - data->last_updated > 5*HZ) || (jiffies < data->last_updated) || !data->valid) { #ifdef DEBUG printk("Starting pcf8574 update\n"); #endif data->read = i2c_smbus_read_byte(client); data->last_updated = jiffies; data->valid = 1; } up(&data->update_lock); } void pcf8574_read(struct i2c_client *client, int operation, int ctl_name, int *nrels_mag, long *results) { struct pcf8574_data *data = client->data; if (operation == SENSORS_PROC_REAL_INFO) *nrels_mag = 0; else if (operation == SENSORS_PROC_REAL_READ) { pcf8574_update_client(client); results[0] = data->read; *nrels_mag = 1; } } void pcf8574_write(struct i2c_client *client, int operation, int ctl_name, int *nrels_mag, long *results) { struct pcf8574_data *data = client->data; if (operation == SENSORS_PROC_REAL_INFO) *nrels_mag = 0; else if (operation == SENSORS_PROC_REAL_READ) { results[0] = data->write; *nrels_mag = 1; } else if (operation == SENSORS_PROC_REAL_WRITE) { if (*nrels_mag == 1) { data->write = results[0]; i2c_smbus_write_byte(client, data->write); } } } static int __init sm_pcf8574_init(void) { printk("pcf8574.o version %s (%s)\n", LM_VERSION, LM_DATE); return i2c_add_driver(&pcf8574_driver); } static void __exit sm_pcf8574_exit(void) { i2c_del_driver(&pcf8574_driver); } MODULE_AUTHOR ("Frodo Looijaard , Philip Edelbrock , Dan Eaton and Aurelien Jarno "); MODULE_DESCRIPTION("PCF8574 driver"); module_init(sm_pcf8574_init); module_exit(sm_pcf8574_exit);