i2c: I2C bus multiplexer driver pca954x
I2C driver for PCA954x I2C multiplexer series. Signed-off-by: Michael Lawnick <ml.lawnick@gmx.de> Acked-by: Rodolfo Giometti <giometti@linux.it> Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Michael Lawnick
Jean Delvare
parent
0826374bff
commit
7f528135da
6 changed files with 377 additions and 1 deletions
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@ -58,6 +58,8 @@ config I2C_MUX
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This support is also available as a module. If so, the module
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will be called i2c-mux.
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source drivers/i2c/muxes/Kconfig
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config I2C_HELPER_AUTO
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bool "Autoselect pertinent helper modules"
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default y
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@ -7,7 +7,7 @@ obj-$(CONFIG_I2C) += i2c-core.o
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obj-$(CONFIG_I2C_SMBUS) += i2c-smbus.o
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obj-$(CONFIG_I2C_CHARDEV) += i2c-dev.o
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obj-$(CONFIG_I2C_MUX) += i2c-mux.o
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obj-y += algos/ busses/
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obj-y += algos/ busses/ muxes/
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ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
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EXTRA_CFLAGS += -DDEBUG
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18
drivers/i2c/muxes/Kconfig
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18
drivers/i2c/muxes/Kconfig
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@ -0,0 +1,18 @@
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#
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# Multiplexer I2C chip drivers configuration
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#
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menu "Multiplexer I2C Chip support"
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depends on I2C_MUX
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config I2C_MUX_PCA954x
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tristate "Philips PCA954x I2C Mux/switches"
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depends on EXPERIMENTAL
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help
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If you say yes here you get support for the Philips PCA954x
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I2C mux/switch devices.
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This driver can also be built as a module. If so, the module
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will be called pca954x.
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endmenu
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8
drivers/i2c/muxes/Makefile
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8
drivers/i2c/muxes/Makefile
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@ -0,0 +1,8 @@
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#
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# Makefile for multiplexer I2C chip drivers.
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obj-$(CONFIG_I2C_MUX_PCA954x) += pca954x.o
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ifeq ($(CONFIG_I2C_DEBUG_BUS),y)
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EXTRA_CFLAGS += -DDEBUG
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endif
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301
drivers/i2c/muxes/pca954x.c
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301
drivers/i2c/muxes/pca954x.c
Normal file
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@ -0,0 +1,301 @@
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/*
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* I2C multiplexer
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*
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* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
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* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
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*
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* This module supports the PCA954x series of I2C multiplexer/switch chips
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* made by Philips Semiconductors.
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* This includes the:
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* PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
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* and PCA9548.
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*
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* These chips are all controlled via the I2C bus itself, and all have a
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* single 8-bit register. The upstream "parent" bus fans out to two,
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* four, or eight downstream busses or channels; which of these
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* are selected is determined by the chip type and register contents. A
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* mux can select only one sub-bus at a time; a switch can select any
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* combination simultaneously.
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*
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* Based on:
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* pca954x.c from Kumar Gala <galak@kernel.crashing.org>
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* Copyright (C) 2006
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*
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* Based on:
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* pca954x.c from Ken Harrenstien
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* Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
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*
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* Based on:
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* i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
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* and
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* pca9540.c from Jean Delvare <khali@linux-fr.org>.
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/device.h>
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#include <linux/i2c.h>
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#include <linux/i2c-mux.h>
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#include <linux/i2c/pca954x.h>
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#define PCA954X_MAX_NCHANS 8
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enum pca_type {
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pca_9540,
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pca_9542,
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pca_9543,
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pca_9544,
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pca_9545,
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pca_9546,
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pca_9547,
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pca_9548,
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};
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struct pca954x {
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enum pca_type type;
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struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
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u8 last_chan; /* last register value */
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};
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struct chip_desc {
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u8 nchans;
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u8 enable; /* used for muxes only */
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enum muxtype {
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pca954x_ismux = 0,
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pca954x_isswi
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} muxtype;
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};
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/* Provide specs for the PCA954x types we know about */
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static const struct chip_desc chips[] = {
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[pca_9540] = {
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.nchans = 2,
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.enable = 0x4,
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.muxtype = pca954x_ismux,
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},
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[pca_9543] = {
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.nchans = 2,
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.muxtype = pca954x_isswi,
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},
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[pca_9544] = {
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.nchans = 4,
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.enable = 0x4,
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.muxtype = pca954x_ismux,
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},
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[pca_9545] = {
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.nchans = 4,
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.muxtype = pca954x_isswi,
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},
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[pca_9547] = {
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.nchans = 8,
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.enable = 0x8,
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.muxtype = pca954x_ismux,
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},
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[pca_9548] = {
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.nchans = 8,
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.muxtype = pca954x_isswi,
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},
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};
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static const struct i2c_device_id pca954x_id[] = {
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{ "pca9540", pca_9540 },
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{ "pca9542", pca_9540 },
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{ "pca9543", pca_9543 },
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{ "pca9544", pca_9544 },
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{ "pca9545", pca_9545 },
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{ "pca9546", pca_9545 },
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{ "pca9547", pca_9547 },
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{ "pca9548", pca_9548 },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, pca954x_id);
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/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
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for this as they will try to lock adapter a second time */
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static int pca954x_reg_write(struct i2c_adapter *adap,
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struct i2c_client *client, u8 val)
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{
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int ret = -ENODEV;
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if (adap->algo->master_xfer) {
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struct i2c_msg msg;
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char buf[1];
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msg.addr = client->addr;
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msg.flags = 0;
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msg.len = 1;
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buf[0] = val;
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msg.buf = buf;
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ret = adap->algo->master_xfer(adap, &msg, 1);
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} else {
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union i2c_smbus_data data;
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ret = adap->algo->smbus_xfer(adap, client->addr,
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client->flags,
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I2C_SMBUS_WRITE,
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val, I2C_SMBUS_BYTE, &data);
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}
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return ret;
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}
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static int pca954x_select_chan(struct i2c_adapter *adap,
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void *client, u32 chan)
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{
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struct pca954x *data = i2c_get_clientdata(client);
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const struct chip_desc *chip = &chips[data->type];
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u8 regval;
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int ret = 0;
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/* we make switches look like muxes, not sure how to be smarter */
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if (chip->muxtype == pca954x_ismux)
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regval = chan | chip->enable;
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else
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regval = 1 << chan;
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/* Only select the channel if its different from the last channel */
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if (data->last_chan != regval) {
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ret = pca954x_reg_write(adap, client, regval);
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data->last_chan = regval;
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}
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return ret;
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}
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static int pca954x_deselect_mux(struct i2c_adapter *adap,
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void *client, u32 chan)
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{
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struct pca954x *data = i2c_get_clientdata(client);
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/* Deselect active channel */
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data->last_chan = 0;
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return pca954x_reg_write(adap, client, data->last_chan);
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}
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/*
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* I2C init/probing/exit functions
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*/
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static int __devinit pca954x_probe(struct i2c_client *client,
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const struct i2c_device_id *id)
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{
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struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
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struct pca954x_platform_data *pdata = client->dev.platform_data;
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int num, force;
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struct pca954x *data;
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int ret = -ENODEV;
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if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
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goto err;
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data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
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if (!data) {
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ret = -ENOMEM;
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goto err;
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}
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i2c_set_clientdata(client, data);
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/* Read the mux register at addr to verify
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* that the mux is in fact present.
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*/
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if (i2c_smbus_read_byte(client) < 0) {
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dev_warn(&client->dev, "probe failed\n");
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goto exit_free;
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}
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data->type = id->driver_data;
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data->last_chan = 0; /* force the first selection */
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/* Now create an adapter for each channel */
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for (num = 0; num < chips[data->type].nchans; num++) {
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force = 0; /* dynamic adap number */
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if (pdata) {
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if (num < pdata->num_modes)
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/* force static number */
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force = pdata->modes[num].adap_id;
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else
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/* discard unconfigured channels */
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break;
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}
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data->virt_adaps[num] =
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i2c_add_mux_adapter(adap, client,
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force, num, pca954x_select_chan,
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(pdata && pdata->modes[num].deselect_on_exit)
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? pca954x_deselect_mux : NULL);
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if (data->virt_adaps[num] == NULL) {
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ret = -ENODEV;
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dev_err(&client->dev,
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"failed to register multiplexed adapter"
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" %d as bus %d\n", num, force);
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goto virt_reg_failed;
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}
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}
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dev_info(&client->dev,
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"registered %d multiplexed busses for I2C %s %s\n",
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num, chips[data->type].muxtype == pca954x_ismux
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? "mux" : "switch", client->name);
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return 0;
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virt_reg_failed:
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for (num--; num >= 0; num--)
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i2c_del_mux_adapter(data->virt_adaps[num]);
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exit_free:
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kfree(data);
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err:
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return ret;
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}
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static int __devexit pca954x_remove(struct i2c_client *client)
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{
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struct pca954x *data = i2c_get_clientdata(client);
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const struct chip_desc *chip = &chips[data->type];
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int i, err;
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for (i = 0; i < chip->nchans; ++i)
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if (data->virt_adaps[i]) {
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err = i2c_del_mux_adapter(data->virt_adaps[i]);
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if (err)
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return err;
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data->virt_adaps[i] = NULL;
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}
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kfree(data);
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return 0;
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}
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static struct i2c_driver pca954x_driver = {
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.driver = {
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.name = "pca954x",
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.owner = THIS_MODULE,
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},
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.probe = pca954x_probe,
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.remove = __devexit_p(pca954x_remove),
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.id_table = pca954x_id,
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};
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static int __init pca954x_init(void)
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{
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return i2c_add_driver(&pca954x_driver);
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}
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static void __exit pca954x_exit(void)
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{
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i2c_del_driver(&pca954x_driver);
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}
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module_init(pca954x_init);
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module_exit(pca954x_exit);
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MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
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MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
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MODULE_LICENSE("GPL v2");
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47
include/linux/i2c/pca954x.h
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47
include/linux/i2c/pca954x.h
Normal file
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@ -0,0 +1,47 @@
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/*
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*
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* pca954x.h - I2C multiplexer/switch support
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*
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* Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
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* Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
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* Michael Lawnick <michael.lawnick.ext@nsn.com>
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*
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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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*
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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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*
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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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#ifndef _LINUX_I2C_PCA954X_H
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#define _LINUX_I2C_PCA954X_H
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/* Platform data for the PCA954x I2C multiplexers */
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/* Per channel initialisation data:
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* @adap_id: bus number for the adapter. 0 = don't care
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* @deselect_on_exit: set this entry to 1, if your H/W needs deselection
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* of this channel after transaction.
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*
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*/
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struct pca954x_platform_mode {
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int adap_id;
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unsigned int deselect_on_exit:1;
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};
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/* Per mux/switch data, used with i2c_register_board_info */
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struct pca954x_platform_data {
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struct pca954x_platform_mode *modes;
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int num_modes;
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};
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#endif /* _LINUX_I2C_PCA954X_H */
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