7 files changed, 230 insertions, 30 deletions

diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index a39e6cff86e7..38319a69bd0a 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -600,12 +600,14 @@ static const struct i2c_algorithm i2c_bit_algo = {
 /*
  * registering functions to load algorithms at runtime
  */
-static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
+static int __i2c_bit_add_bus(struct i2c_adapter *adap,
+                             int (*add_adapter)(struct i2c_adapter *))
 {
         struct i2c_algo_bit_data *bit_adap = adap->algo_data;
+        int ret;
 
         if (bit_test) {
-                int ret = test_bus(bit_adap, adap->name);
+                ret = test_bus(bit_adap, adap->name);
                 if (ret < 0)
                         return -ENODEV;
         }
@@ -614,30 +616,27 @@ static int i2c_bit_prepare_bus(struct i2c_adapter *adap)
         adap->algo = &i2c_bit_algo;
         adap->retries = 3;
 
+        ret = add_adapter(adap);
+        if (ret < 0)
+                return ret;
+
+        /* Complain if SCL can't be read */
+        if (bit_adap->getscl == NULL) {
+                dev_warn(&adap->dev, "Not I2C compliant: can't read SCL\n");
+                dev_warn(&adap->dev, "Bus may be unreliable\n");
+        }
         return 0;
 }
 
 int i2c_bit_add_bus(struct i2c_adapter *adap)
 {
-        int err;
-
-        err = i2c_bit_prepare_bus(adap);
-        if (err)
-                return err;
-
-        return i2c_add_adapter(adap);
+        return __i2c_bit_add_bus(adap, i2c_add_adapter);
 }
 EXPORT_SYMBOL(i2c_bit_add_bus);
 
 int i2c_bit_add_numbered_bus(struct i2c_adapter *adap)
 {
-        int err;
-
-        err = i2c_bit_prepare_bus(adap);
-        if (err)
-                return err;
-
-        return i2c_add_numbered_adapter(adap);
+        return __i2c_bit_add_bus(adap, i2c_add_numbered_adapter);
 }
 EXPORT_SYMBOL(i2c_bit_add_numbered_bus);
 
diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index 02835ce7ff4b..7979aef7ee7b 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -72,6 +72,7 @@
 #include <linux/acpi.h>
 #include <linux/io.h>
 #include <linux/dmi.h>
+#include <linux/slab.h>
 
 /* I801 SMBus address offsets */
 #define SMBHSTSTS(p)    (0 + (p)->smba)
diff --git a/drivers/i2c/busses/i2c-nforce2.c b/drivers/i2c/busses/i2c-nforce2.c
index a605a5029cfe..ff1e127dfea8 100644
--- a/drivers/i2c/busses/i2c-nforce2.c
+++ b/drivers/i2c/busses/i2c-nforce2.c
@@ -432,7 +432,7 @@ static int __devinit nforce2_probe(struct pci_dev *dev, const struct pci_device_
 
 static void __devexit nforce2_remove(struct pci_dev *dev)
 {
-        struct nforce2_smbus *smbuses = (void*) pci_get_drvdata(dev);
+        struct nforce2_smbus *smbuses = pci_get_drvdata(dev);
 
         nforce2_set_reference(NULL);
         if (smbuses[0].base) {
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 6b4cc567645b..c7db6980e3a3 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1362,7 +1362,7 @@ EXPORT_SYMBOL(i2c_transfer);
  *
  * Returns negative errno, or else the number of bytes written.
  */
-int i2c_master_send(struct i2c_client *client, const char *buf, int count)
+int i2c_master_send(const struct i2c_client *client, const char *buf, int count)
 {
         int ret;
         struct i2c_adapter *adap = client->adapter;
@@ -1389,7 +1389,7 @@ EXPORT_SYMBOL(i2c_master_send);
  *
  * Returns negative errno, or else the number of bytes read.
  */
-int i2c_master_recv(struct i2c_client *client, char *buf, int count)
+int i2c_master_recv(const struct i2c_client *client, char *buf, int count)
 {
         struct i2c_adapter *adap = client->adapter;
         struct i2c_msg msg;
@@ -1679,7 +1679,7 @@ static int i2c_smbus_check_pec(u8 cpec, struct i2c_msg *msg)
  * This executes the SMBus "receive byte" protocol, returning negative errno
  * else the byte received from the device.
  */
-s32 i2c_smbus_read_byte(struct i2c_client *client)
+s32 i2c_smbus_read_byte(const struct i2c_client *client)
 {
         union i2c_smbus_data data;
         int status;
@@ -1699,7 +1699,7 @@ EXPORT_SYMBOL(i2c_smbus_read_byte);
  * This executes the SMBus "send byte" protocol, returning negative errno
  * else zero on success.
  */
-s32 i2c_smbus_write_byte(struct i2c_client *client, u8 value)
+s32 i2c_smbus_write_byte(const struct i2c_client *client, u8 value)
 {
         return i2c_smbus_xfer(client->adapter, client->addr, client->flags,
                               I2C_SMBUS_WRITE, value, I2C_SMBUS_BYTE, NULL);
@@ -1714,7 +1714,7 @@ EXPORT_SYMBOL(i2c_smbus_write_byte);
  * This executes the SMBus "read byte" protocol, returning negative errno
  * else a data byte received from the device.
  */
-s32 i2c_smbus_read_byte_data(struct i2c_client *client, u8 command)
+s32 i2c_smbus_read_byte_data(const struct i2c_client *client, u8 command)
 {
         union i2c_smbus_data data;
         int status;
@@ -1735,7 +1735,8 @@ EXPORT_SYMBOL(i2c_smbus_read_byte_data);
  * This executes the SMBus "write byte" protocol, returning negative errno
  * else zero on success.
  */
-s32 i2c_smbus_write_byte_data(struct i2c_client *client, u8 command, u8 value)
+s32 i2c_smbus_write_byte_data(const struct i2c_client *client, u8 command,
+                              u8 value)
 {
         union i2c_smbus_data data;
         data.byte = value;
@@ -1753,7 +1754,7 @@ EXPORT_SYMBOL(i2c_smbus_write_byte_data);
  * This executes the SMBus "read word" protocol, returning negative errno
  * else a 16-bit unsigned "word" received from the device.
  */
-s32 i2c_smbus_read_word_data(struct i2c_client *client, u8 command)
+s32 i2c_smbus_read_word_data(const struct i2c_client *client, u8 command)
 {
         union i2c_smbus_data data;
         int status;
@@ -1774,7 +1775,8 @@ EXPORT_SYMBOL(i2c_smbus_read_word_data);
  * This executes the SMBus "write word" protocol, returning negative errno
  * else zero on success.
  */
-s32 i2c_smbus_write_word_data(struct i2c_client *client, u8 command, u16 value)
+s32 i2c_smbus_write_word_data(const struct i2c_client *client, u8 command,
+                              u16 value)
 {
         union i2c_smbus_data data;
         data.word = value;
@@ -1793,7 +1795,8 @@ EXPORT_SYMBOL(i2c_smbus_write_word_data);
  * This executes the SMBus "process call" protocol, returning negative errno
  * else a 16-bit unsigned "word" received from the device.
  */
-s32 i2c_smbus_process_call(struct i2c_client *client, u8 command, u16 value)
+s32 i2c_smbus_process_call(const struct i2c_client *client, u8 command,
+                           u16 value)
 {
         union i2c_smbus_data data;
         int status;
@@ -1821,7 +1824,7 @@ EXPORT_SYMBOL(i2c_smbus_process_call);
  * support this; its emulation through I2C messaging relies on a specific
  * mechanism (I2C_M_RECV_LEN) which may not be implemented.
  */
-s32 i2c_smbus_read_block_data(struct i2c_client *client, u8 command,
+s32 i2c_smbus_read_block_data(const struct i2c_client *client, u8 command,
                               u8 *values)
 {
         union i2c_smbus_data data;
@@ -1848,7 +1851,7 @@ EXPORT_SYMBOL(i2c_smbus_read_block_data);
  * This executes the SMBus "block write" protocol, returning negative errno
  * else zero on success.
  */
-s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
+s32 i2c_smbus_write_block_data(const struct i2c_client *client, u8 command,
                                u8 length, const u8 *values)
 {
         union i2c_smbus_data data;
@@ -1864,7 +1867,7 @@ s32 i2c_smbus_write_block_data(struct i2c_client *client, u8 command,
 EXPORT_SYMBOL(i2c_smbus_write_block_data);
 
 /* Returns the number of read bytes */
-s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
+s32 i2c_smbus_read_i2c_block_data(const struct i2c_client *client, u8 command,
                                   u8 length, u8 *values)
 {
         union i2c_smbus_data data;
@@ -1884,7 +1887,7 @@ s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client, u8 command,
 }
 EXPORT_SYMBOL(i2c_smbus_read_i2c_block_data);
 
-s32 i2c_smbus_write_i2c_block_data(struct i2c_client *client, u8 command,
+s32 i2c_smbus_write_i2c_block_data(const struct i2c_client *client, u8 command,
                                    u8 length, const u8 *values)
 {
         union i2c_smbus_data data;
diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 4d91d80bfd23..90b7a0163899 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -5,6 +5,18 @@
 menu "Multiplexer I2C Chip support"
         depends on I2C_MUX
 
+config I2C_MUX_GPIO
+        tristate "GPIO-based I2C multiplexer"
+        depends on GENERIC_GPIO
+        help
+          If you say yes to this option, support will be included for a
+          GPIO based I2C multiplexer. This driver provides access to
+          I2C busses connected through a MUX, which is controlled
+          through GPIO pins.
+
+          This driver can also be built as a module.  If so, the module
+          will be called gpio-i2cmux.
+
 config I2C_MUX_PCA9541
         tristate "NXP PCA9541 I2C Master Selector"
         depends on EXPERIMENTAL
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index d743806d9b42..4640436ea61f 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -1,6 +1,7 @@
 #
 # Makefile for multiplexer I2C chip drivers.
 
+obj-$(CONFIG_I2C_MUX_GPIO)      += gpio-i2cmux.o
 obj-$(CONFIG_I2C_MUX_PCA9541)   += pca9541.o
 obj-$(CONFIG_I2C_MUX_PCA954x)   += pca954x.o
 
diff --git a/drivers/i2c/muxes/gpio-i2cmux.c b/drivers/i2c/muxes/gpio-i2cmux.c
new file mode 100644
index 000000000000..7b6ce624cd6e
--- /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");