diff options
| -rw-r--r-- | Documentation/i2c/chips/pcf8575 | 72 | ||||
| -rw-r--r-- | drivers/i2c/chips/Kconfig | 16 | ||||
| -rw-r--r-- | drivers/i2c/chips/Makefile | 1 | ||||
| -rw-r--r-- | drivers/i2c/chips/pcf8575.c | 214 |
4 files changed, 302 insertions, 1 deletions
diff --git a/Documentation/i2c/chips/pcf8575 b/Documentation/i2c/chips/pcf8575 new file mode 100644 index 0000000..25f5698 --- /dev/null +++ b/Documentation/i2c/chips/pcf8575 @@ -0,0 +1,72 @@ +About the PCF8575 chip and the pcf8575 kernel driver +==================================================== + +The PCF8575 chip is produced by the following manufacturers: + + * Philips NXP + http://www.nxp.com/#/pip/cb=[type=product,path=50807/41735/41850,final=PCF8575_3]|pip=[pip=PCF8575_3][0] + + * Texas Instruments + http://focus.ti.com/docs/prod/folders/print/pcf8575.html + + +Some vendors sell small PCB's with the PCF8575 mounted on it. You can connect +such a board to a Linux host via e.g. an USB to I2C interface. Examples of +PCB boards with a PCF8575: + + * SFE Breakout Board for PCF8575 I2C Expander by RobotShop + http://www.robotshop.ca/home/products/robot-parts/electronics/adapters-converters/sfe-pcf8575-i2c-expander-board.html + + * Breakout Board for PCF8575 I2C Expander by Spark Fun Electronics + http://www.sparkfun.com/commerce/product_info.php?products_id=8130 + + +Description +----------- +The PCF8575 chip is a 16-bit I/O expander for the I2C bus. Up to eight of +these chips can be connected to the same I2C bus. You can find this +chip on some custom designed hardware, but you won't find it on PC +motherboards. + +The PCF8575 chip consists of a 16-bit quasi-bidirectional port and an I2C-bus +interface. Each of the sixteen I/O's can be independently used as an input or +an output. To set up an I/O pin as an input, you have to write a 1 to the +corresponding output. + +For more information please see the datasheet. + + +Detection +--------- + +There is no method known to detect whether a chip on a given I2C address is +a PCF8575 or whether it is any other I2C device. So there are two alternatives +to let the driver find the installed PCF8575 devices: +- Load this driver after any other I2C driver for I2C devices with addresses + in the range 0x20 .. 0x27. +- Pass the I2C bus and address of the installed PCF8575 devices explicitly to + the driver at load time via the probe=... or force=... parameters. + +/sys interface +-------------- + +For each address on which a PCF8575 chip was found or forced the following +files will be created under /sys: +* /sys/bus/i2c/devices/<bus>-<address>/read +* /sys/bus/i2c/devices/<bus>-<address>/write +where bus is the I2C bus number (0, 1, ...) and address is the four-digit +hexadecimal representation of the 7-bit I2C address of the PCF8575 +(0020 .. 0027). + +The read file is read-only. Reading it will trigger an I2C read and will hence +report the current input state for the pins configured as inputs, and the +current output value for the pins configured as outputs. + +The write file is read-write. Writing a value to it will configure all pins +as output for which the corresponding bit is zero. Reading the write file will +return the value last written, or -EAGAIN if no value has yet been written to +the write file. + +On module initialization the configuration of the chip is not changed -- the +chip is left in the state it was already configured in through either power-up +or through previous I2C write actions. diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig index 2e1c24f..17702b3 100644 --- a/drivers/i2c/chips/Kconfig +++ b/drivers/i2c/chips/Kconfig @@ -57,7 +57,7 @@ config SENSORS_PCF8574 default n help If you say yes here you get support for Philips PCF8574 and - PCF8574A chips. + PCF8574A chips. These chips are 8-bit I/O expanders for the I2C bus. This driver can also be built as a module. If so, the module will be called pcf8574. @@ -65,6 +65,20 @@ config SENSORS_PCF8574 These devices are hard to detect and rarely found on mainstream hardware. If unsure, say N. +config PCF8575 + tristate "Philips PCF8575" + default n + help + If you say yes here you get support for Philips PCF8575 chip. + This chip is a 16-bit I/O expander for the I2C bus. Several other + chip manufacturers sell equivalent chips, e.g. Texas Instruments. + + This driver can also be built as a module. If so, the module + will be called pcf8575. + + This device is hard to detect and is rarely found on mainstream + hardware. If unsure, say N. + config SENSORS_PCA9539 tristate "Philips PCA9539 16-bit I/O port" depends on EXPERIMENTAL diff --git a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile index ca924e1..50d4734 100644 --- a/drivers/i2c/chips/Makefile +++ b/drivers/i2c/chips/Makefile @@ -10,6 +10,7 @@ obj-$(CONFIG_SENSORS_MAX6875) += max6875.o obj-$(CONFIG_SENSORS_M41T00) += m41t00.o obj-$(CONFIG_SENSORS_PCA9539) += pca9539.o obj-$(CONFIG_SENSORS_PCF8574) += pcf8574.o +obj-$(CONFIG_PCF8575) += pcf8575.o obj-$(CONFIG_SENSORS_PCF8591) += pcf8591.o obj-$(CONFIG_ISP1301_OMAP) += isp1301_omap.o obj-$(CONFIG_TPS65010) += tps65010.o diff --git a/drivers/i2c/chips/pcf8575.c b/drivers/i2c/chips/pcf8575.c new file mode 100644 index 0000000..db3c877 --- /dev/null +++ b/drivers/i2c/chips/pcf8575.c @@ -0,0 +1,214 @@ +/* + pcf8575.c + + About the PCF8575 chip: the PCF8575 is a 16-bit I/O expander for the I2C bus + produced by a.o. Philips Semiconductors. + + Copyright (C) 2006 Michael Hennerich, Analog Devices Inc. + <hennerich@blackfin.uclinux.org> + Based on pcf8574.c. + + Copyright (c) 2007 Bart Van Assche <bart.vanassche@gmail.com>. + Ported this driver from ucLinux to the mainstream Linux kernel. + + 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. +*/ + +#include <linux/module.h> +#include <linux/init.h> +#include <linux/i2c.h> +#include <linux/slab.h> /* kzalloc() */ +#include <linux/sysfs.h> /* sysfs_create_group() */ + +/* Addresses to scan */ +static unsigned short normal_i2c[] = { + 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, + I2C_CLIENT_END +}; + +/* Insmod parameters */ +I2C_CLIENT_INSMOD; + + +/* Each client has this additional data */ +struct pcf8575_data { + struct i2c_client client; + int write; /* last written value, or error code */ +}; + +static int pcf8575_attach_adapter(struct i2c_adapter *adapter); +static int pcf8575_detect(struct i2c_adapter *adapter, int address, int kind); +static int pcf8575_detach_client(struct i2c_client *client); + +/* This is the driver that will be inserted */ +static struct i2c_driver pcf8575_driver = { + .driver = { + .owner = THIS_MODULE, + .name = "pcf8575", + }, + .attach_adapter = pcf8575_attach_adapter, + .detach_client = pcf8575_detach_client, +}; + +/* following are the sysfs callback functions */ +static ssize_t show_read(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct i2c_client *client = to_i2c_client(dev); + u16 val; + u8 iopin_state[2]; + + i2c_master_recv(client, iopin_state, 2); + + val = iopin_state[0]; + val |= iopin_state[1] << 8; + + return sprintf(buf, "%u\n", val); +} + +static DEVICE_ATTR(read, S_IRUGO, show_read, NULL); + +static ssize_t show_write(struct device *dev, struct device_attribute *attr, + char *buf) +{ + struct pcf8575_data *data = dev_get_drvdata(dev); + if (data->write < 0) + return data->write; + return sprintf(buf, "%d\n", data->write); +} + +static ssize_t set_write(struct device *dev, struct device_attribute *attr, + const char *buf, size_t count) +{ + struct i2c_client *client = to_i2c_client(dev); + struct pcf8575_data *data = i2c_get_clientdata(client); + unsigned long val = simple_strtoul(buf, NULL, 10); + u8 iopin_state[2]; + + if (val > 0xffff) + return -EINVAL; + + data->write = val; + + iopin_state[0] = val & 0xFF; + iopin_state[1] = val >> 8; + + i2c_master_send(client, iopin_state, 2); + + return count; +} + +static DEVICE_ATTR(write, S_IWUSR | S_IRUGO, show_write, set_write); + +static struct attribute *pcf8575_attributes[] = { + &dev_attr_read.attr, + &dev_attr_write.attr, + NULL +}; + +static const struct attribute_group pcf8575_attr_group = { + .attrs = pcf8575_attributes, +}; + +/* + * Real code + */ + +static int pcf8575_attach_adapter(struct i2c_adapter *adapter) +{ + return i2c_probe(adapter, &addr_data, pcf8575_detect); +} + +/* This function is called by i2c_probe */ +static int pcf8575_detect(struct i2c_adapter *adapter, int address, int kind) +{ + struct i2c_client *client; + struct pcf8575_data *data; + int err = 0; + + if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) + 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. */ + data = kzalloc(sizeof(struct pcf8575_data), GFP_KERNEL); + if (!data) { + err = -ENOMEM; + goto exit; + } + + client = &data->client; + i2c_set_clientdata(client, data); + client->addr = address; + client->adapter = adapter; + client->driver = &pcf8575_driver; + strlcpy(client->name, "pcf8575", I2C_NAME_SIZE); + data->write = -EAGAIN; + + /* This is the place to detect whether the chip at the specified + address really is a PCF8575 chip. However, there is no method known + to detect whether an I2C chip is a PCF8575 or any other I2C chip. */ + + /* Tell the I2C layer a new client has arrived */ + err = i2c_attach_client(client); + if (err) + goto exit_free; + + /* Register sysfs hooks */ + err = sysfs_create_group(&client->dev.kobj, &pcf8575_attr_group); + if (err) + goto exit_detach; + + return 0; + +exit_detach: + i2c_detach_client(client); +exit_free: + kfree(data); +exit: + return err; +} + +static int pcf8575_detach_client(struct i2c_client *client) +{ + int err; + + sysfs_remove_group(&client->dev.kobj, &pcf8575_attr_group); + + err = i2c_detach_client(client); + if (err) + return err; + + kfree(i2c_get_clientdata(client)); + return 0; +} + +static int __init pcf8575_init(void) +{ + return i2c_add_driver(&pcf8575_driver); +} + +static void __exit pcf8575_exit(void) +{ + i2c_del_driver(&pcf8575_driver); +} + +MODULE_AUTHOR("Michael Hennerich <hennerich@blackfin.uclinux.org>, " + "Bart Van Assche <bart.vanassche@gmail.com>"); +MODULE_DESCRIPTION("pcf8575 driver"); +MODULE_LICENSE("GPL"); + +module_init(pcf8575_init); +module_exit(pcf8575_exit); |
