Added missing tegra files.HEADmaster

3 files changed, 999 insertions, 0 deletions

diff --git a/drivers/i2c/muxes/gpio-i2cmux.c b/drivers/i2c/muxes/gpio-i2cmux.c
new file mode 100644
index 00000000000..7b6ce624cd6
--- /dev/null
+++ b/drivers/i2c/muxes/gpio-i2cmux.c
@@ -0,0 +1,184 @@
+/*
+ * I2C multiplexer using GPIO API
+ *
+ * Peter Korsgaard <peter.korsgaard@barco.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/gpio-i2cmux.h>
+#include <linux/platform_device.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/gpio.h>
+
+struct gpiomux {
+        struct i2c_adapter *parent;
+        struct i2c_adapter **adap; /* child busses */
+        struct gpio_i2cmux_platform_data data;
+};
+
+static void gpiomux_set(const struct gpiomux *mux, unsigned val)
+{
+        int i;
+
+        for (i = 0; i < mux->data.n_gpios; i++)
+                gpio_set_value(mux->data.gpios[i], val & (1 << i));
+}
+
+static int gpiomux_select(struct i2c_adapter *adap, void *data, u32 chan)
+{
+        struct gpiomux *mux = data;
+
+        gpiomux_set(mux, mux->data.values[chan]);
+
+        return 0;
+}
+
+static int gpiomux_deselect(struct i2c_adapter *adap, void *data, u32 chan)
+{
+        struct gpiomux *mux = data;
+
+        gpiomux_set(mux, mux->data.idle);
+
+        return 0;
+}
+
+static int __devinit gpiomux_probe(struct platform_device *pdev)
+{
+        struct gpiomux *mux;
+        struct gpio_i2cmux_platform_data *pdata;
+        struct i2c_adapter *parent;
+        int (*deselect) (struct i2c_adapter *, void *, u32);
+        unsigned initial_state;
+        int i, ret;
+
+        pdata = pdev->dev.platform_data;
+        if (!pdata) {
+                dev_err(&pdev->dev, "Missing platform data\n");
+                return -ENODEV;
+        }
+
+        parent = i2c_get_adapter(pdata->parent);
+        if (!parent) {
+                dev_err(&pdev->dev, "Parent adapter (%d) not found\n",
+                        pdata->parent);
+                return -ENODEV;
+        }
+
+        mux = kzalloc(sizeof(*mux), GFP_KERNEL);
+        if (!mux) {
+                ret = -ENOMEM;
+                goto alloc_failed;
+        }
+
+        mux->parent = parent;
+        mux->data = *pdata;
+        mux->adap = kzalloc(sizeof(struct i2c_adapter *) * pdata->n_values,
+                            GFP_KERNEL);
+        if (!mux->adap) {
+                ret = -ENOMEM;
+                goto alloc_failed2;
+        }
+
+        if (pdata->idle != GPIO_I2CMUX_NO_IDLE) {
+                initial_state = pdata->idle;
+                deselect = gpiomux_deselect;
+        } else {
+                initial_state = pdata->values[0];
+                deselect = NULL;
+        }
+
+        for (i = 0; i < pdata->n_gpios; i++) {
+                ret = gpio_request(pdata->gpios[i], "gpio-i2cmux");
+                if (ret)
+                        goto err_request_gpio;
+                gpio_direction_output(pdata->gpios[i],
+                                      initial_state & (1 << i));
+        }
+
+        for (i = 0; i < pdata->n_values; i++) {
+                u32 nr = pdata->base_nr ? (pdata->base_nr + i) : 0;
+
+                mux->adap[i] = i2c_add_mux_adapter(parent, mux, nr, i,
+                                                   gpiomux_select, deselect);
+                if (!mux->adap[i]) {
+                        ret = -ENODEV;
+                        dev_err(&pdev->dev, "Failed to add adapter %d\n", i);
+                        goto add_adapter_failed;
+                }
+        }
+
+        dev_info(&pdev->dev, "%d port mux on %s adapter\n",
+                 pdata->n_values, parent->name);
+
+        platform_set_drvdata(pdev, mux);
+
+        return 0;
+
+add_adapter_failed:
+        for (; i > 0; i--)
+                i2c_del_mux_adapter(mux->adap[i - 1]);
+        i = pdata->n_gpios;
+err_request_gpio:
+        for (; i > 0; i--)
+                gpio_free(pdata->gpios[i - 1]);
+        kfree(mux->adap);
+alloc_failed2:
+        kfree(mux);
+alloc_failed:
+        i2c_put_adapter(parent);
+
+        return ret;
+}
+
+static int __devexit gpiomux_remove(struct platform_device *pdev)
+{
+        struct gpiomux *mux = platform_get_drvdata(pdev);
+        int i;
+
+        for (i = 0; i < mux->data.n_values; i++)
+                i2c_del_mux_adapter(mux->adap[i]);
+
+        for (i = 0; i < mux->data.n_gpios; i++)
+                gpio_free(mux->data.gpios[i]);
+
+        platform_set_drvdata(pdev, NULL);
+        i2c_put_adapter(mux->parent);
+        kfree(mux->adap);
+        kfree(mux);
+
+        return 0;
+}
+
+static struct platform_driver gpiomux_driver = {
+        .probe  = gpiomux_probe,
+        .remove = __devexit_p(gpiomux_remove),
+        .driver = {
+                .owner  = THIS_MODULE,
+                .name   = "gpio-i2cmux",
+        },
+};
+
+static int __init gpiomux_init(void)
+{
+        return platform_driver_register(&gpiomux_driver);
+}
+
+static void __exit gpiomux_exit(void)
+{
+        platform_driver_unregister(&gpiomux_driver);
+}
+
+module_init(gpiomux_init);
+module_exit(gpiomux_exit);
+
+MODULE_DESCRIPTION("GPIO-based I2C multiplexer driver");
+MODULE_AUTHOR("Peter Korsgaard <peter.korsgaard@barco.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-i2cmux");
diff --git a/drivers/i2c/muxes/pca9541.c b/drivers/i2c/muxes/pca9541.c
new file mode 100644
index 00000000000..ed699c5aa79
--- /dev/null
+++ b/drivers/i2c/muxes/pca9541.c
@@ -0,0 +1,411 @@
+/*
+ * I2C multiplexer driver for PCA9541 bus master selector
+ *
+ * Copyright (c) 2010 Ericsson AB.
+ *
+ * Author: Guenter Roeck <guenter.roeck@ericsson.com>
+ *
+ * Derived from:
+ *  pca954x.c
+ *
+ *  Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
+ *  Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/delay.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+
+#include <linux/i2c/pca954x.h>
+
+/*
+ * The PCA9541 is a bus master selector. It supports two I2C masters connected
+ * to a single slave bus.
+ *
+ * Before each bus transaction, a master has to acquire bus ownership. After the
+ * transaction is complete, bus ownership has to be released. This fits well
+ * into the I2C multiplexer framework, which provides select and release
+ * functions for this purpose. For this reason, this driver is modeled as
+ * single-channel I2C bus multiplexer.
+ *
+ * This driver assumes that the two bus masters are controlled by two different
+ * hosts. If a single host controls both masters, platform code has to ensure
+ * that only one of the masters is instantiated at any given time.
+ */
+
+#define PCA9541_CONTROL         0x01
+#define PCA9541_ISTAT           0x02
+
+#define PCA9541_CTL_MYBUS       (1 << 0)
+#define PCA9541_CTL_NMYBUS      (1 << 1)
+#define PCA9541_CTL_BUSON       (1 << 2)
+#define PCA9541_CTL_NBUSON      (1 << 3)
+#define PCA9541_CTL_BUSINIT     (1 << 4)
+#define PCA9541_CTL_TESTON      (1 << 6)
+#define PCA9541_CTL_NTESTON     (1 << 7)
+
+#define PCA9541_ISTAT_INTIN     (1 << 0)
+#define PCA9541_ISTAT_BUSINIT   (1 << 1)
+#define PCA9541_ISTAT_BUSOK     (1 << 2)
+#define PCA9541_ISTAT_BUSLOST   (1 << 3)
+#define PCA9541_ISTAT_MYTEST    (1 << 6)
+#define PCA9541_ISTAT_NMYTEST   (1 << 7)
+
+#define BUSON           (PCA9541_CTL_BUSON | PCA9541_CTL_NBUSON)
+#define MYBUS           (PCA9541_CTL_MYBUS | PCA9541_CTL_NMYBUS)
+#define mybus(x)        (!((x) & MYBUS) || ((x) & MYBUS) == MYBUS)
+#define busoff(x)       (!((x) & BUSON) || ((x) & BUSON) == BUSON)
+
+/* arbitration timeouts, in jiffies */
+#define ARB_TIMEOUT     (HZ / 8)        /* 125 ms until forcing bus ownership */
+#define ARB2_TIMEOUT    (HZ / 4)        /* 250 ms until acquisition failure */
+
+/* arbitration retry delays, in us */
+#define SELECT_DELAY_SHORT      50
+#define SELECT_DELAY_LONG       1000
+
+struct pca9541 {
+        struct i2c_adapter *mux_adap;
+        unsigned long select_timeout;
+        unsigned long arb_timeout;
+};
+
+static const struct i2c_device_id pca9541_id[] = {
+        {"pca9541", 0},
+        {}
+};
+
+MODULE_DEVICE_TABLE(i2c, pca9541_id);
+
+/*
+ * Write to chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
+ * as they will try to lock the adapter a second time.
+ */
+static int pca9541_reg_write(struct i2c_client *client, u8 command, u8 val)
+{
+        struct i2c_adapter *adap = client->adapter;
+        int ret;
+
+        if (adap->algo->master_xfer) {
+                struct i2c_msg msg;
+                char buf[2];
+
+                msg.addr = client->addr;
+                msg.flags = 0;
+                msg.len = 2;
+                buf[0] = command;
+                buf[1] = val;
+                msg.buf = buf;
+                ret = adap->algo->master_xfer(adap, &msg, 1);
+        } else {
+                union i2c_smbus_data data;
+
+                data.byte = val;
+                ret = adap->algo->smbus_xfer(adap, client->addr,
+                                             client->flags,
+                                             I2C_SMBUS_WRITE,
+                                             command,
+                                             I2C_SMBUS_BYTE_DATA, &data);
+        }
+
+        return ret;
+}
+
+/*
+ * Read from chip register. Don't use i2c_transfer()/i2c_smbus_xfer()
+ * as they will try to lock adapter a second time.
+ */
+static int pca9541_reg_read(struct i2c_client *client, u8 command)
+{
+        struct i2c_adapter *adap = client->adapter;
+        int ret;
+        u8 val;
+
+        if (adap->algo->master_xfer) {
+                struct i2c_msg msg[2] = {
+                        {
+                                .addr = client->addr,
+                                .flags = 0,
+                                .len = 1,
+                                .buf = &command
+                        },
+                        {
+                                .addr = client->addr,
+                                .flags = I2C_M_RD,
+                                .len = 1,
+                                .buf = &val
+                        }
+                };
+                ret = adap->algo->master_xfer(adap, msg, 2);
+                if (ret == 2)
+                        ret = val;
+                else if (ret >= 0)
+                        ret = -EIO;
+        } else {
+                union i2c_smbus_data data;
+
+                ret = adap->algo->smbus_xfer(adap, client->addr,
+                                             client->flags,
+                                             I2C_SMBUS_READ,
+                                             command,
+                                             I2C_SMBUS_BYTE_DATA, &data);
+                if (!ret)
+                        ret = data.byte;
+        }
+        return ret;
+}
+
+/*
+ * Arbitration management functions
+ */
+
+/* Release bus. Also reset NTESTON and BUSINIT if it was set. */
+static void pca9541_release_bus(struct i2c_client *client)
+{
+        int reg;
+
+        reg = pca9541_reg_read(client, PCA9541_CONTROL);
+        if (reg >= 0 && !busoff(reg) && mybus(reg))
+                pca9541_reg_write(client, PCA9541_CONTROL,
+                                  (reg & PCA9541_CTL_NBUSON) >> 1);
+}
+
+/*
+ * Arbitration is defined as a two-step process. A bus master can only activate
+ * the slave bus if it owns it; otherwise it has to request ownership first.
+ * This multi-step process ensures that access contention is resolved
+ * gracefully.
+ *
+ * Bus  Ownership       Other master    Action
+ * state                requested access
+ * ----------------------------------------------------
+ * off  -               yes             wait for arbitration timeout or
+ *                                      for other master to drop request
+ * off  no              no              take ownership
+ * off  yes             no              turn on bus
+ * on   yes             -               done
+ * on   no              -               wait for arbitration timeout or
+ *                                      for other master to release bus
+ *
+ * The main contention point occurs if the slave bus is off and both masters
+ * request ownership at the same time. In this case, one master will turn on
+ * the slave bus, believing that it owns it. The other master will request
+ * bus ownership. Result is that the bus is turned on, and master which did
+ * _not_ own the slave bus before ends up owning it.
+ */
+
+/* Control commands per PCA9541 datasheet */
+static const u8 pca9541_control[16] = {
+        4, 0, 1, 5, 4, 4, 5, 5, 0, 0, 1, 1, 0, 4, 5, 1
+};
+
+/*
+ * Channel arbitration
+ *
+ * Return values:
+ *  <0: error
+ *  0 : bus not acquired
+ *  1 : bus acquired
+ */
+static int pca9541_arbitrate(struct i2c_client *client)
+{
+        struct pca9541 *data = i2c_get_clientdata(client);
+        int reg;
+
+        reg = pca9541_reg_read(client, PCA9541_CONTROL);
+        if (reg < 0)
+                return reg;
+
+        if (busoff(reg)) {
+                int istat;
+                /*
+                 * Bus is off. Request ownership or turn it on unless
+                 * other master requested ownership.
+                 */
+                istat = pca9541_reg_read(client, PCA9541_ISTAT);
+                if (!(istat & PCA9541_ISTAT_NMYTEST)
+                    || time_is_before_eq_jiffies(data->arb_timeout)) {
+                        /*
+                         * Other master did not request ownership,
+                         * or arbitration timeout expired. Take the bus.
+                         */
+                        pca9541_reg_write(client,
+                                          PCA9541_CONTROL,
+                                          pca9541_control[reg & 0x0f]
+                                          | PCA9541_CTL_NTESTON);
+                        data->select_timeout = SELECT_DELAY_SHORT;
+                } else {
+                        /*
+                         * Other master requested ownership.
+                         * Set extra long timeout to give it time to acquire it.
+                         */
+                        data->select_timeout = SELECT_DELAY_LONG * 2;
+                }
+        } else if (mybus(reg)) {
+                /*
+                 * Bus is on, and we own it. We are done with acquisition.
+                 * Reset NTESTON and BUSINIT, then return success.
+                 */
+                if (reg & (PCA9541_CTL_NTESTON | PCA9541_CTL_BUSINIT))
+                        pca9541_reg_write(client,
+                                          PCA9541_CONTROL,
+                                          reg & ~(PCA9541_CTL_NTESTON
+                                                  | PCA9541_CTL_BUSINIT));
+                return 1;
+        } else {
+                /*
+                 * Other master owns the bus.
+                 * If arbitration timeout has expired, force ownership.
+                 * Otherwise request it.
+                 */
+                data->select_timeout = SELECT_DELAY_LONG;
+                if (time_is_before_eq_jiffies(data->arb_timeout)) {
+                        /* Time is up, take the bus and reset it. */
+                        pca9541_reg_write(client,
+                                          PCA9541_CONTROL,
+                                          pca9541_control[reg & 0x0f]
+                                          | PCA9541_CTL_BUSINIT
+                                          | PCA9541_CTL_NTESTON);
+                } else {
+                        /* Request bus ownership if needed */
+                        if (!(reg & PCA9541_CTL_NTESTON))
+                                pca9541_reg_write(client,
+                                                  PCA9541_CONTROL,
+                                                  reg | PCA9541_CTL_NTESTON);
+                }
+        }
+        return 0;
+}
+
+static int pca9541_select_chan(struct i2c_adapter *adap, void *client, u32 chan)
+{
+        struct pca9541 *data = i2c_get_clientdata(client);
+        int ret;
+        unsigned long timeout = jiffies + ARB2_TIMEOUT;
+                /* give up after this time */
+
+        data->arb_timeout = jiffies + ARB_TIMEOUT;
+                /* force bus ownership after this time */
+
+        do {
+                ret = pca9541_arbitrate(client);
+                if (ret)
+                        return ret < 0 ? ret : 0;
+
+                if (data->select_timeout == SELECT_DELAY_SHORT)
+                        udelay(data->select_timeout);
+                else
+                        msleep(data->select_timeout / 1000);
+        } while (time_is_after_eq_jiffies(timeout));
+
+        return -ETIMEDOUT;
+}
+
+static int pca9541_release_chan(struct i2c_adapter *adap,
+                                void *client, u32 chan)
+{
+        pca9541_release_bus(client);
+        return 0;
+}
+
+/*
+ * I2C init/probing/exit functions
+ */
+static int pca9541_probe(struct i2c_client *client,
+                         const struct i2c_device_id *id)
+{
+        struct i2c_adapter *adap = client->adapter;
+        struct pca954x_platform_data *pdata = client->dev.platform_data;
+        struct pca9541 *data;
+        int force;
+        int ret = -ENODEV;
+
+        if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE_DATA))
+                goto err;
+
+        data = kzalloc(sizeof(struct pca9541), GFP_KERNEL);
+        if (!data) {
+                ret = -ENOMEM;
+                goto err;
+        }
+
+        i2c_set_clientdata(client, data);
+
+        /*
+         * I2C accesses are unprotected here.
+         * We have to lock the adapter before releasing the bus.
+         */
+        i2c_lock_adapter(adap);
+        pca9541_release_bus(client);
+        i2c_unlock_adapter(adap);
+
+        /* Create mux adapter */
+
+        force = 0;
+        if (pdata)
+                force = pdata->modes[0].adap_id;
+        data->mux_adap = i2c_add_mux_adapter(adap, client, force, 0,
+                                             pca9541_select_chan,
+                                             pca9541_release_chan);
+
+        if (data->mux_adap == NULL) {
+                dev_err(&client->dev, "failed to register master selector\n");
+                goto exit_free;
+        }
+
+        dev_info(&client->dev, "registered master selector for I2C %s\n",
+                 client->name);
+
+        return 0;
+
+exit_free:
+        kfree(data);
+err:
+        return ret;
+}
+
+static int pca9541_remove(struct i2c_client *client)
+{
+        struct pca9541 *data = i2c_get_clientdata(client);
+
+        i2c_del_mux_adapter(data->mux_adap);
+
+        kfree(data);
+        return 0;
+}
+
+static struct i2c_driver pca9541_driver = {
+        .driver = {
+                   .name = "pca9541",
+                   .owner = THIS_MODULE,
+                   },
+        .probe = pca9541_probe,
+        .remove = pca9541_remove,
+        .id_table = pca9541_id,
+};
+
+static int __init pca9541_init(void)
+{
+        return i2c_add_driver(&pca9541_driver);
+}
+
+static void __exit pca9541_exit(void)
+{
+        i2c_del_driver(&pca9541_driver);
+}
+
+module_init(pca9541_init);
+module_exit(pca9541_exit);
+
+MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
+MODULE_DESCRIPTION("PCA9541 I2C master selector driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/i2c/muxes/pca954x.c b/drivers/i2c/muxes/pca954x.c
new file mode 100644
index 00000000000..dd14ae38d3e
--- /dev/null
+++ b/drivers/i2c/muxes/pca954x.c
@@ -0,0 +1,404 @@
+/*
+ * I2C multiplexer
+ *
+ * Copyright (c) 2008-2009 Rodolfo Giometti <giometti@linux.it>
+ * Copyright (c) 2008-2009 Eurotech S.p.A. <info@eurotech.it>
+ *
+ * This module supports the PCA954x series of I2C multiplexer/switch chips
+ * made by Philips Semiconductors.
+ * This includes the:
+ *       PCA9540, PCA9542, PCA9543, PCA9544, PCA9545, PCA9546, PCA9547
+ *       and PCA9548.
+ *
+ * These chips are all controlled via the I2C bus itself, and all have a
+ * single 8-bit register. The upstream "parent" bus fans out to two,
+ * four, or eight downstream busses or channels; which of these
+ * are selected is determined by the chip type and register contents. A
+ * mux can select only one sub-bus at a time; a switch can select any
+ * combination simultaneously.
+ *
+ * Based on:
+ *      pca954x.c from Kumar Gala <galak@kernel.crashing.org>
+ * Copyright (C) 2006
+ *
+ * Based on:
+ *      pca954x.c from Ken Harrenstien
+ * Copyright (C) 2004 Google, Inc. (Ken Harrenstien)
+ *
+ * Based on:
+ *      i2c-virtual_cb.c from Brian Kuschak <bkuschak@yahoo.com>
+ * and
+ *      pca9540.c from Jean Delvare <khali@linux-fr.org>.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/i2c.h>
+#include <linux/i2c-mux.h>
+#include <linux/regulator/consumer.h>
+#include <linux/err.h>
+#include <linux/delay.h>
+
+#include <linux/i2c/pca954x.h>
+
+#define PCA954X_MAX_NCHANS 8
+
+enum pca_type {
+        pca_9540,
+        pca_9542,
+        pca_9543,
+        pca_9544,
+        pca_9545,
+        pca_9546,
+        pca_9547,
+        pca_9548,
+};
+
+struct pca954x {
+        enum pca_type type;
+        struct i2c_adapter *virt_adaps[PCA954X_MAX_NCHANS];
+
+        u8 last_chan;           /* last register value */
+        struct regulator *vcc_reg;
+        struct regulator *i2c_reg;
+};
+
+struct chip_desc {
+        u8 nchans;
+        u8 enable;      /* used for muxes only */
+        enum muxtype {
+                pca954x_ismux = 0,
+                pca954x_isswi
+        } muxtype;
+};
+
+/* Provide specs for the PCA954x types we know about */
+static const struct chip_desc chips[] = {
+        [pca_9540] = {
+                .nchans = 2,
+                .enable = 0x4,
+                .muxtype = pca954x_ismux,
+        },
+        [pca_9543] = {
+                .nchans = 2,
+                .muxtype = pca954x_isswi,
+        },
+        [pca_9544] = {
+                .nchans = 4,
+                .enable = 0x4,
+                .muxtype = pca954x_ismux,
+        },
+        [pca_9545] = {
+                .nchans = 4,
+                .muxtype = pca954x_isswi,
+        },
+        [pca_9547] = {
+                .nchans = 8,
+                .enable = 0x8,
+                .muxtype = pca954x_ismux,
+        },
+        [pca_9548] = {
+                .nchans = 8,
+                .muxtype = pca954x_isswi,
+        },
+};
+
+static const struct i2c_device_id pca954x_id[] = {
+        { "pca9540", pca_9540 },
+        { "pca9542", pca_9540 },
+        { "pca9543", pca_9543 },
+        { "pca9544", pca_9544 },
+        { "pca9545", pca_9545 },
+        { "pca9546", pca_9545 },
+        { "pca9547", pca_9547 },
+        { "pca9548", pca_9548 },
+        { }
+};
+MODULE_DEVICE_TABLE(i2c, pca954x_id);
+
+/* Write to mux register. Don't use i2c_transfer()/i2c_smbus_xfer()
+   for this as they will try to lock adapter a second time */
+static int pca954x_reg_write(struct i2c_adapter *adap,
+                             struct i2c_client *client, u8 val)
+{
+        int ret = -ENODEV;
+        struct pca954x *data = i2c_get_clientdata(client);
+
+        /* Increase ref count for pca954x vcc */
+        if (data->vcc_reg) {
+                ret = regulator_enable(data->vcc_reg);
+                if (ret) {
+                        dev_err(&client->dev, "%s: failed to enable vcc\n",
+                                __func__);
+                        goto vcc_regulator_failed;
+                }
+        }
+        /* Increase ref count for pca954x vcc_i2c */
+        if (data->i2c_reg) {
+                ret = regulator_enable(data->i2c_reg);
+                if (ret) {
+                        dev_err(&client->dev, "%s: failed to enable vcc_i2c\n",
+                                __func__);
+                        goto i2c_regulator_failed;
+                }
+        }
+
+        if (adap->algo->master_xfer) {
+                struct i2c_msg msg;
+                char buf[1];
+
+                msg.addr = client->addr;
+                msg.flags = 0;
+                msg.len = 1;
+                buf[0] = val;
+                msg.buf = buf;
+                ret = adap->algo->master_xfer(adap, &msg, 1);
+        } else {
+                union i2c_smbus_data data;
+                ret = adap->algo->smbus_xfer(adap, client->addr,
+                                             client->flags,
+                                             I2C_SMBUS_WRITE,
+                                             val, I2C_SMBUS_BYTE, &data);
+        }
+
+        /* Decrease ref count for pca954x vcc_i2c */
+        if (data->i2c_reg)
+                regulator_disable(data->i2c_reg);
+
+i2c_regulator_failed:
+        /* Decrease ref count for pca954x vcc */
+        if (data->vcc_reg)
+                regulator_disable(data->vcc_reg);
+vcc_regulator_failed:
+        return ret;
+}
+
+static int pca954x_select_chan(struct i2c_adapter *adap,
+                               void *client, u32 chan)
+{
+        struct pca954x *data = i2c_get_clientdata(client);
+        const struct chip_desc *chip = &chips[data->type];
+        u8 regval;
+        int ret = 0;
+
+        /* we make switches look like muxes, not sure how to be smarter */
+        if (chip->muxtype == pca954x_ismux)
+                regval = chan | chip->enable;
+        else
+                regval = 1 << chan;
+
+        /* Only select the channel if its different from the last channel */
+        if (data->last_chan != regval) {
+                ret = pca954x_reg_write(adap, client, regval);
+                data->last_chan = regval;
+        }
+
+        return ret;
+}
+
+static int pca954x_deselect_mux(struct i2c_adapter *adap,
+                                void *client, u32 chan)
+{
+        struct pca954x *data = i2c_get_clientdata(client);
+
+        /* Deselect active channel */
+        data->last_chan = 0;
+        return pca954x_reg_write(adap, client, data->last_chan);
+}
+
+/*
+ * I2C init/probing/exit functions
+ */
+static int pca954x_probe(struct i2c_client *client,
+                         const struct i2c_device_id *id)
+{
+        struct i2c_adapter *adap = to_i2c_adapter(client->dev.parent);
+        struct pca954x_platform_data *pdata = client->dev.platform_data;
+        int num, force;
+        struct pca954x *data;
+        int ret = -ENODEV;
+
+        if (!i2c_check_functionality(adap, I2C_FUNC_SMBUS_BYTE))
+                goto err;
+
+        data = kzalloc(sizeof(struct pca954x), GFP_KERNEL);
+        if (!data) {
+                ret = -ENOMEM;
+                goto err;
+        }
+
+        i2c_set_clientdata(client, data);
+
+        /* Get regulator pointer for pca954x vcc */
+        data->vcc_reg = regulator_get(&client->dev, "vcc");
+        if (PTR_ERR(data->vcc_reg) == -ENODEV)
+                data->vcc_reg = NULL;
+        else if (IS_ERR(data->vcc_reg)) {
+                dev_err(&client->dev, "%s: failed to get vcc\n",
+                        __func__);
+                ret = PTR_ERR(data->vcc_reg);
+                goto exit_free;
+        }
+        /* Get regulator pointer for pca954x vcc_i2c */
+        data->i2c_reg = regulator_get(&client->dev, "vcc_i2c");
+        if (PTR_ERR(data->i2c_reg) == -ENODEV)
+                data->i2c_reg = NULL;
+        else if (IS_ERR(data->i2c_reg)) {
+                dev_err(&client->dev, "%s: failed to get vcc_i2c\n",
+                        __func__);
+                ret = PTR_ERR(data->i2c_reg);
+                regulator_put(data->vcc_reg);
+                goto exit_free;
+        }
+
+        /* Increase ref count for pca954x vcc */
+        if (data->vcc_reg) {
+                pr_info("%s: enable vcc\n", __func__);
+                ret = regulator_enable(data->vcc_reg);
+                if (ret) {
+                        dev_err(&client->dev, "%s: failed to enable vcc\n",
+                                __func__);
+                        goto exit_regulator_put;
+                }
+        }
+        /* Increase ref count for pca954x vcc_i2c */
+        if (data->i2c_reg) {
+                pr_info("%s: enable vcc_i2c\n", __func__);
+                ret = regulator_enable(data->i2c_reg);
+                if (ret) {
+                        dev_err(&client->dev, "%s: failed to enable vcc_i2c\n",
+                                __func__);
+                        goto exit_vcc_regulator_disable;
+                }
+        }
+
+        /*
+         * Power-On Reset takes time.
+         * I2C is ready after Power-On Reset.
+         */
+        msleep(1);
+
+        /* Write the mux register at addr to verify
+         * that the mux is in fact present. This also
+         * initializes the mux to disconnected state.
+         */
+        if (i2c_smbus_write_byte(client, 0) < 0) {
+                dev_warn(&client->dev, "probe failed\n");
+                goto exit_regulator_disable;
+        }
+
+        /* Decrease ref count for pca954x vcc */
+        if (data->vcc_reg)
+                regulator_disable(data->vcc_reg);
+        /* Decrease ref count for pca954x vcc_i2c */
+        if (data->i2c_reg)
+                regulator_disable(data->i2c_reg);
+
+        data->type = id->driver_data;
+        data->last_chan = 0;               /* force the first selection */
+
+        /* Now create an adapter for each channel */
+        for (num = 0; num < chips[data->type].nchans; num++) {
+                force = 0;                        /* dynamic adap number */
+                if (pdata) {
+                        if (num < pdata->num_modes)
+                                /* force static number */
+                                force = pdata->modes[num].adap_id;
+                        else
+                                /* discard unconfigured channels */
+                                break;
+                }
+
+                data->virt_adaps[num] =
+                        i2c_add_mux_adapter(adap, client,
+                                force, num, pca954x_select_chan,
+                                (pdata && pdata->modes[num].deselect_on_exit)
+                                        ? pca954x_deselect_mux : NULL);
+
+                if (data->virt_adaps[num] == NULL) {
+                        ret = -ENODEV;
+                        dev_err(&client->dev,
+                                "failed to register multiplexed adapter"
+                                " %d as bus %d\n", num, force);
+                        goto virt_reg_failed;
+                }
+        }
+
+        dev_info(&client->dev,
+                 "registered %d multiplexed busses for I2C %s %s\n",
+                 num, chips[data->type].muxtype == pca954x_ismux
+                                ? "mux" : "switch", client->name);
+
+        return 0;
+
+virt_reg_failed:
+        for (num--; num >= 0; num--)
+                i2c_del_mux_adapter(data->virt_adaps[num]);
+exit_regulator_disable:
+        if (data->i2c_reg)
+                regulator_disable(data->i2c_reg);
+exit_vcc_regulator_disable:
+        if (data->vcc_reg)
+                regulator_disable(data->vcc_reg);
+exit_regulator_put:
+        regulator_put(data->i2c_reg);
+        regulator_put(data->vcc_reg);
+exit_free:
+        kfree(data);
+err:
+        return ret;
+}
+
+static int pca954x_remove(struct i2c_client *client)
+{
+        struct pca954x *data = i2c_get_clientdata(client);
+        const struct chip_desc *chip = &chips[data->type];
+        int i, err;
+
+        for (i = 0; i < chip->nchans; ++i)
+                if (data->virt_adaps[i]) {
+                        err = i2c_del_mux_adapter(data->virt_adaps[i]);
+                        if (err)
+                                return err;
+                        data->virt_adaps[i] = NULL;
+                }
+
+        regulator_put(data->i2c_reg);
+        regulator_put(data->vcc_reg);
+
+        kfree(data);
+        return 0;
+}
+
+static struct i2c_driver pca954x_driver = {
+        .driver         = {
+                .name   = "pca954x",
+                .owner  = THIS_MODULE,
+        },
+        .probe          = pca954x_probe,
+        .remove         = pca954x_remove,
+        .id_table       = pca954x_id,
+};
+
+static int __init pca954x_init(void)
+{
+        return i2c_add_driver(&pca954x_driver);
+}
+
+static void __exit pca954x_exit(void)
+{
+        i2c_del_driver(&pca954x_driver);
+}
+
+module_init(pca954x_init);
+module_exit(pca954x_exit);
+
+MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
+MODULE_DESCRIPTION("PCA954x I2C mux/switch driver");
+MODULE_LICENSE("GPL v2");