Commit 69dd204b authored by's avatar Committed by Greg Kroah-Hartman

[PATCH] I2C: add new pca9539 driver

This is an i2c driver for the Philips PCA9539 (16 bit I/O port).
It uses the new i2c-sysfs interfaces.
The patch includes documentation.
It depends on the patch that renames "i2c-sysfs.h" to "hwmon-sysfs.h"
Signed-off-by: default avatarBen Gardner <>
Signed-off-by: default avatarGreg Kroah-Hartman <>
parent 10c08f81
Kernel driver pca9539
Supported chips:
* Philips PCA9539
Prefix: 'pca9539'
Addresses scanned: 0x74 - 0x77
Author: Ben Gardner <>
The Philips PCA9539 is a 16 bit low power I/O device.
All 16 lines can be individually configured as an input or output.
The input sense can also be inverted.
The 16 lines are split between two bytes.
Sysfs entries
Each is a byte that maps to the 8 I/O bits.
A '0' suffix is for bits 0-7, while '1' is for bits 8-15.
input[01] - read the current value
output[01] - sets the output value
direction[01] - direction of each bit: 1=input, 0=output
invert[01] - toggle the input bit sense
input reads the actual state of the line and is always available.
The direction defaults to input for all channels.
General Remarks
Note that each output, direction, and invert entry controls 8 lines.
You should use the read, modify, write sequence.
For example. to set output bit 0 of 1.
val=$(cat output0)
val=$(( $val | 1 ))
echo $val > output0
......@@ -440,6 +440,16 @@ config SENSORS_PCF8574
This driver can also be built as a module. If so, the module
will be called pcf8574.
config SENSORS_PCA9539
tristate "Philips PCA9539 16-bit I/O port"
depends on I2C && EXPERIMENTAL
If you say yes here you get support for the Philips PCA9539
16-bit I/O port.
This driver can also be built as a module. If so, the module
will be called pca9539.
config SENSORS_PCF8591
tristate "Philips PCF8591"
depends on I2C && EXPERIMENTAL
......@@ -35,6 +35,7 @@ obj-$(CONFIG_SENSORS_MAX1619) += max1619.o
obj-$(CONFIG_SENSORS_MAX6875) += max6875.o
obj-$(CONFIG_SENSORS_M41T00) += m41t00.o
obj-$(CONFIG_SENSORS_PC87360) += pc87360.o
obj-$(CONFIG_SENSORS_PCA9539) += pca9539.o
obj-$(CONFIG_SENSORS_PCF8574) += pcf8574.o
obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.o
obj-$(CONFIG_SENSORS_RTC8564) += rtc8564.o
pca9539.c - 16-bit I/O port with interrupt and reset
Copyright (C) 2005 Ben Gardner <>
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; version 2 of the License.
#include <linux/module.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon-sysfs.h>
#include <linux/i2c-sensor.h>
/* Addresses to scan */
static unsigned short normal_i2c[] = {0x74, 0x75, 0x76, 0x77, I2C_CLIENT_END};
static unsigned int normal_isa[] = {I2C_CLIENT_ISA_END};
/* Insmod parameters */
enum pca9539_cmd
PCA9539_INPUT_0 = 0,
PCA9539_INPUT_1 = 1,
PCA9539_OUTPUT_0 = 2,
PCA9539_OUTPUT_1 = 3,
PCA9539_INVERT_0 = 4,
PCA9539_INVERT_1 = 5,
PCA9539_DIRECTION_0 = 6,
PCA9539_DIRECTION_1 = 7,
static int pca9539_attach_adapter(struct i2c_adapter *adapter);
static int pca9539_detect(struct i2c_adapter *adapter, int address, int kind);
static int pca9539_detach_client(struct i2c_client *client);
/* This is the driver that will be inserted */
static struct i2c_driver pca9539_driver = {
.owner = THIS_MODULE,
.name = "pca9539",
.flags = I2C_DF_NOTIFY,
.attach_adapter = pca9539_attach_adapter,
.detach_client = pca9539_detach_client,
struct pca9539_data {
struct i2c_client client;
/* following are the sysfs callback functions */
static ssize_t pca9539_show(struct device *dev, struct device_attribute *attr,
char *buf)
struct sensor_device_attribute *psa = to_sensor_dev_attr(attr);
struct i2c_client *client = to_i2c_client(dev);
return sprintf(buf, "%d\n", i2c_smbus_read_byte_data(client,
static ssize_t pca9539_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t count)
struct sensor_device_attribute *psa = to_sensor_dev_attr(attr);
struct i2c_client *client = to_i2c_client(dev);
unsigned long val = simple_strtoul(buf, NULL, 0);
if (val > 0xff)
return -EINVAL;
i2c_smbus_write_byte_data(client, psa->index, val);
return count;
/* Define the device attributes */
#define PCA9539_ENTRY_RO(name, cmd_idx) \
static SENSOR_DEVICE_ATTR(name, S_IRUGO, pca9539_show, NULL, cmd_idx)
#define PCA9539_ENTRY_RW(name, cmd_idx) \
static SENSOR_DEVICE_ATTR(name, S_IRUGO | S_IWUSR, pca9539_show, \
pca9539_store, cmd_idx)
PCA9539_ENTRY_RO(input0, PCA9539_INPUT_0);
PCA9539_ENTRY_RO(input1, PCA9539_INPUT_1);
PCA9539_ENTRY_RW(output0, PCA9539_OUTPUT_0);
PCA9539_ENTRY_RW(output1, PCA9539_OUTPUT_1);
PCA9539_ENTRY_RW(invert0, PCA9539_INVERT_0);
PCA9539_ENTRY_RW(invert1, PCA9539_INVERT_1);
PCA9539_ENTRY_RW(direction0, PCA9539_DIRECTION_0);
PCA9539_ENTRY_RW(direction1, PCA9539_DIRECTION_1);
static struct attribute *pca9539_attributes[] = {
static struct attribute_group pca9539_defattr_group = {
.attrs = pca9539_attributes,
static int pca9539_attach_adapter(struct i2c_adapter *adapter)
return i2c_detect(adapter, &addr_data, pca9539_detect);
/* This function is called by i2c_detect */
static int pca9539_detect(struct i2c_adapter *adapter, int address, int kind)
struct i2c_client *new_client;
struct pca9539_data *data;
int err = 0;
if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
goto exit;
/* OK. For now, we presume we have a valid client. We now create the
client structure, even though we cannot fill it completely yet. */
if (!(data = kmalloc(sizeof(struct pca9539_data), GFP_KERNEL))) {
err = -ENOMEM;
goto exit;
memset(data, 0, sizeof(struct pca9539_data));
new_client = &data->client;
i2c_set_clientdata(new_client, data);
new_client->addr = address;
new_client->adapter = adapter;
new_client->driver = &pca9539_driver;
new_client->flags = 0;
/* Detection: the pca9539 only has 8 registers (0-7).
A read of 7 should succeed, but a read of 8 should fail. */
if ((i2c_smbus_read_byte_data(new_client, 7) < 0) ||
(i2c_smbus_read_byte_data(new_client, 8) >= 0))
goto exit_kfree;
strlcpy(new_client->name, "pca9539", I2C_NAME_SIZE);
/* Tell the I2C layer a new client has arrived */
if ((err = i2c_attach_client(new_client)))
goto exit_kfree;
/* Register sysfs hooks (don't care about failure) */
sysfs_create_group(&new_client->dev.kobj, &pca9539_defattr_group);
return 0;
return err;
static int pca9539_detach_client(struct i2c_client *client)
int err;
if ((err = i2c_detach_client(client))) {
dev_err(&client->dev, "Client deregistration failed.\n");
return err;
return 0;
static int __init pca9539_init(void)
return i2c_add_driver(&pca9539_driver);
static void __exit pca9539_exit(void)
MODULE_AUTHOR("Ben Gardner <>");
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