From 0a57274ea026c2b7670683947b6cc08b195148cf Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Sun, 24 Oct 2010 18:16:57 +0200
Subject: [PATCH 01/13] i2c: Fix Kconfig dependencies

drivers/i2c/algos/Kconfig makes all the algorithms dependent on
!I2C_HELPER_AUTO, which triggers a Kconfig warning about broken
dependencies when some driver selects one of the algorithms. Ideally
we would make only the prompts dependent on !I2C_HELPER_AUTO, however
Kconfig doesn't currently support that. So we have to redefine the
symbols separately for the I2C_HELPER_AUTO=y case.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Michal Marek <mmarek@suse.cz>
---
 drivers/i2c/Kconfig       |  3 ++-
 drivers/i2c/algos/Kconfig | 12 ++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/Kconfig b/drivers/i2c/Kconfig
index 30f06e956bfb..b923074b2cbe 100644
--- a/drivers/i2c/Kconfig
+++ b/drivers/i2c/Kconfig
@@ -75,7 +75,8 @@ config I2C_HELPER_AUTO
 	  In doubt, say Y.
 
 config I2C_SMBUS
-	tristate "SMBus-specific protocols" if !I2C_HELPER_AUTO
+	tristate
+	prompt "SMBus-specific protocols" if !I2C_HELPER_AUTO
 	help
 	  Say Y here if you want support for SMBus extensions to the I2C
 	  specification. At the moment, the only supported extension is
diff --git a/drivers/i2c/algos/Kconfig b/drivers/i2c/algos/Kconfig
index 7b2ce4a08524..3998dd620a03 100644
--- a/drivers/i2c/algos/Kconfig
+++ b/drivers/i2c/algos/Kconfig
@@ -15,3 +15,15 @@ config I2C_ALGOPCA
 	tristate "I2C PCA 9564 interfaces"
 
 endmenu
+
+# In automatic configuration mode, we still have to define the
+# symbols to avoid unmet dependencies.
+
+if I2C_HELPER_AUTO
+config I2C_ALGOBIT
+	tristate
+config I2C_ALGOPCF
+	tristate
+config I2C_ALGOPCA
+	tristate
+endif

From 323584436db0cb05286425d4dfd9516fce88487f Mon Sep 17 00:00:00 2001
From: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Date: Sun, 24 Oct 2010 18:16:57 +0200
Subject: [PATCH 02/13] i2c-pca-platform: Change device name of request_irq

i2c->adap.name shouldn't be used in request_irq.
Instead the driver name "i2c-pca-platform" should be used.

Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.yj@renesas.com>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Cc: stable@kernel.org
Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
 drivers/i2c/busses/i2c-pca-platform.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-pca-platform.c b/drivers/i2c/busses/i2c-pca-platform.c
index 5f6d7f89e225..ace67995d7de 100644
--- a/drivers/i2c/busses/i2c-pca-platform.c
+++ b/drivers/i2c/busses/i2c-pca-platform.c
@@ -224,7 +224,7 @@ static int __devinit i2c_pca_pf_probe(struct platform_device *pdev)
 
 	if (irq) {
 		ret = request_irq(irq, i2c_pca_pf_handler,
-			IRQF_TRIGGER_FALLING, i2c->adap.name, i2c);
+			IRQF_TRIGGER_FALLING, pdev->name, i2c);
 		if (ret)
 			goto e_reqirq;
 	}

From d582963a027fd63f8dfc97a0bf3654d4380e34ce Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Sun, 24 Oct 2010 18:16:57 +0200
Subject: [PATCH 03/13] i2c: Simplify i2c_parent_is_i2c_adapter

Only i2c devices can have their type set to i2c_adapter_type, so
testing the bus type is redundant.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Michael Lawnick <ml.lawnick@gmx.de>
---
 include/linux/i2c.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 4bae0b72ed3c..9391a491501a 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -387,7 +387,6 @@ static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
 static inline int i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
 {
 	return adapter->dev.parent != NULL
-		&& adapter->dev.parent->bus == &i2c_bus_type
 		&& adapter->dev.parent->type == &i2c_adapter_type;
 }
 

From 97cc4d49cfcda1c2dad89c00b62a25b628ce2115 Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Sun, 24 Oct 2010 18:16:57 +0200
Subject: [PATCH 04/13] i2c: Let i2c_parent_is_i2c_adapter return the parent
 adapter

This makes the calling site's code clearer IMHO.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Michael Lawnick <ml.lawnick@gmx.de>
---
 drivers/i2c/i2c-core.c | 30 ++++++++++++++++++------------
 drivers/i2c/i2c-dev.c  | 13 ++++++-------
 include/linux/i2c.h    | 11 ++++++++---
 3 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index bea4c5021d26..40e563de0508 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -425,14 +425,14 @@ static int __i2c_check_addr_busy(struct device *dev, void *addrp)
 /* walk up mux tree */
 static int i2c_check_mux_parents(struct i2c_adapter *adapter, int addr)
 {
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 	int result;
 
 	result = device_for_each_child(&adapter->dev, &addr,
 					__i2c_check_addr_busy);
 
-	if (!result && i2c_parent_is_i2c_adapter(adapter))
-		result = i2c_check_mux_parents(
-				    to_i2c_adapter(adapter->dev.parent), addr);
+	if (!result && parent)
+		result = i2c_check_mux_parents(parent, addr);
 
 	return result;
 }
@@ -453,11 +453,11 @@ static int i2c_check_mux_children(struct device *dev, void *addrp)
 
 static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
 {
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 	int result = 0;
 
-	if (i2c_parent_is_i2c_adapter(adapter))
-		result = i2c_check_mux_parents(
-				    to_i2c_adapter(adapter->dev.parent), addr);
+	if (parent)
+		result = i2c_check_mux_parents(parent, addr);
 
 	if (!result)
 		result = device_for_each_child(&adapter->dev, &addr,
@@ -472,8 +472,10 @@ static int i2c_check_addr_busy(struct i2c_adapter *adapter, int addr)
  */
 void i2c_lock_adapter(struct i2c_adapter *adapter)
 {
-	if (i2c_parent_is_i2c_adapter(adapter))
-		i2c_lock_adapter(to_i2c_adapter(adapter->dev.parent));
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+
+	if (parent)
+		i2c_lock_adapter(parent);
 	else
 		rt_mutex_lock(&adapter->bus_lock);
 }
@@ -485,8 +487,10 @@ EXPORT_SYMBOL_GPL(i2c_lock_adapter);
  */
 static int i2c_trylock_adapter(struct i2c_adapter *adapter)
 {
-	if (i2c_parent_is_i2c_adapter(adapter))
-		return i2c_trylock_adapter(to_i2c_adapter(adapter->dev.parent));
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+
+	if (parent)
+		return i2c_trylock_adapter(parent);
 	else
 		return rt_mutex_trylock(&adapter->bus_lock);
 }
@@ -497,8 +501,10 @@ static int i2c_trylock_adapter(struct i2c_adapter *adapter)
  */
 void i2c_unlock_adapter(struct i2c_adapter *adapter)
 {
-	if (i2c_parent_is_i2c_adapter(adapter))
-		i2c_unlock_adapter(to_i2c_adapter(adapter->dev.parent));
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
+
+	if (parent)
+		i2c_unlock_adapter(parent);
 	else
 		rt_mutex_unlock(&adapter->bus_lock);
 }
diff --git a/drivers/i2c/i2c-dev.c b/drivers/i2c/i2c-dev.c
index 5f3a52d517c3..cec0f3ba97f8 100644
--- a/drivers/i2c/i2c-dev.c
+++ b/drivers/i2c/i2c-dev.c
@@ -192,13 +192,12 @@ static int i2cdev_check(struct device *dev, void *addrp)
 /* walk up mux tree */
 static int i2cdev_check_mux_parents(struct i2c_adapter *adapter, int addr)
 {
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 	int result;
 
 	result = device_for_each_child(&adapter->dev, &addr, i2cdev_check);
-
-	if (!result && i2c_parent_is_i2c_adapter(adapter))
-		result = i2cdev_check_mux_parents(
-				    to_i2c_adapter(adapter->dev.parent), addr);
+	if (!result && parent)
+		result = i2cdev_check_mux_parents(parent, addr);
 
 	return result;
 }
@@ -222,11 +221,11 @@ static int i2cdev_check_mux_children(struct device *dev, void *addrp)
    driver bound to it, as NOT busy. */
 static int i2cdev_check_addr(struct i2c_adapter *adapter, unsigned int addr)
 {
+	struct i2c_adapter *parent = i2c_parent_is_i2c_adapter(adapter);
 	int result = 0;
 
-	if (i2c_parent_is_i2c_adapter(adapter))
-		result = i2cdev_check_mux_parents(
-				    to_i2c_adapter(adapter->dev.parent), addr);
+	if (parent)
+		result = i2cdev_check_mux_parents(parent, addr);
 
 	if (!result)
 		result = device_for_each_child(&adapter->dev, &addr,
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 9391a491501a..1f66fa06a97c 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -384,10 +384,15 @@ static inline void i2c_set_adapdata(struct i2c_adapter *dev, void *data)
 	dev_set_drvdata(&dev->dev, data);
 }
 
-static inline int i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
+static inline struct i2c_adapter *
+i2c_parent_is_i2c_adapter(const struct i2c_adapter *adapter)
 {
-	return adapter->dev.parent != NULL
-		&& adapter->dev.parent->type == &i2c_adapter_type;
+	struct device *parent = adapter->dev.parent;
+
+	if (parent != NULL && parent->type == &i2c_adapter_type)
+		return to_i2c_adapter(parent);
+	else
+		return NULL;
 }
 
 /* Adapter locking functions, exported for shared pin cases */

From a8d7be818fbe0f8a4e7dc251712958ca369f9d45 Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Sun, 24 Oct 2010 18:16:58 +0200
Subject: [PATCH 05/13] i2c: Remove unneeded inclusions of <linux/i2c-id.h>

These drivers don't use anything which is defined in <linux/i2c-id.h>.
This header file was never meant to be included directly anyway, and
will be deleted soon.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Ben Dooks <ben-linux@fluff.org>
Acked-by: Dave Airlie <airlied@linux.ie>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
---
 drivers/gpu/drm/nouveau/nouveau_i2c.h | 1 -
 drivers/gpu/drm/radeon/radeon_mode.h  | 1 -
 drivers/i2c/busses/i2c-ibm_iic.c      | 1 -
 drivers/i2c/busses/i2c-nuc900.c       | 1 -
 drivers/i2c/busses/i2c-pxa.c          | 1 -
 drivers/i2c/busses/i2c-s3c2410.c      | 1 -
 drivers/video/aty/radeon_i2c.c        | 1 -
 drivers/video/i810/i810.h             | 1 -
 drivers/video/intelfb/intelfb_i2c.c   | 1 -
 drivers/video/savage/savagefb.h       | 1 -
 10 files changed, 10 deletions(-)

diff --git a/drivers/gpu/drm/nouveau/nouveau_i2c.h b/drivers/gpu/drm/nouveau/nouveau_i2c.h
index f71cb32f7571..cfe7c8426d1d 100644
--- a/drivers/gpu/drm/nouveau/nouveau_i2c.h
+++ b/drivers/gpu/drm/nouveau/nouveau_i2c.h
@@ -24,7 +24,6 @@
 #define __NOUVEAU_I2C_H__
 
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/i2c-algo-bit.h>
 #include "drm_dp_helper.h"
 
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index 17a6602b5885..454c1dc7ea45 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -36,7 +36,6 @@
 #include <drm_dp_helper.h>
 #include <drm_fixed.h>
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/i2c-algo-bit.h>
 
 struct radeon_bo;
diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index 89eedf45d30e..6e3c38240336 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -41,7 +41,6 @@
 #include <asm/irq.h>
 #include <linux/io.h>
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/of_platform.h>
 #include <linux/of_i2c.h>
 
diff --git a/drivers/i2c/busses/i2c-nuc900.c b/drivers/i2c/busses/i2c-nuc900.c
index 92d770d7bbc2..72434263787b 100644
--- a/drivers/i2c/busses/i2c-nuc900.c
+++ b/drivers/i2c/busses/i2c-nuc900.c
@@ -16,7 +16,6 @@
 #include <linux/module.h>
 
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/init.h>
 #include <linux/time.h>
 #include <linux/interrupt.h>
diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index c94e51b2651e..f4c19a97e0b3 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -22,7 +22,6 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/init.h>
 #include <linux/time.h>
 #include <linux/sched.h>
diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index bf831bf81587..6a292ea5e35c 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -24,7 +24,6 @@
 #include <linux/module.h>
 
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/init.h>
 #include <linux/time.h>
 #include <linux/interrupt.h>
diff --git a/drivers/video/aty/radeon_i2c.c b/drivers/video/aty/radeon_i2c.c
index 359fc64e761a..78d1f4cd1fe0 100644
--- a/drivers/video/aty/radeon_i2c.c
+++ b/drivers/video/aty/radeon_i2c.c
@@ -7,7 +7,6 @@
 
 
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/i2c-algo-bit.h>
 
 #include <asm/io.h>
diff --git a/drivers/video/i810/i810.h b/drivers/video/i810/i810.h
index 328ae6c673ec..f37de60ecc59 100644
--- a/drivers/video/i810/i810.h
+++ b/drivers/video/i810/i810.h
@@ -17,7 +17,6 @@
 #include <linux/agp_backend.h>
 #include <linux/fb.h>
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/i2c-algo-bit.h>
 #include <video/vga.h>
 
diff --git a/drivers/video/intelfb/intelfb_i2c.c b/drivers/video/intelfb/intelfb_i2c.c
index 487f2be47460..3300bd31d9d7 100644
--- a/drivers/video/intelfb/intelfb_i2c.c
+++ b/drivers/video/intelfb/intelfb_i2c.c
@@ -32,7 +32,6 @@ USE OR OTHER DEALINGS IN THE SOFTWARE.
 #include <linux/fb.h>
 
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/i2c-algo-bit.h>
 
 #include <asm/io.h>
diff --git a/drivers/video/savage/savagefb.h b/drivers/video/savage/savagefb.h
index 8bfdfc3c5234..e4c3f214eb8e 100644
--- a/drivers/video/savage/savagefb.h
+++ b/drivers/video/savage/savagefb.h
@@ -13,7 +13,6 @@
 #define __SAVAGEFB_H__
 
 #include <linux/i2c.h>
-#include <linux/i2c-id.h>
 #include <linux/i2c-algo-bit.h>
 #include <linux/mutex.h>
 #include <video/vga.h>

From ef9d9b8fb696850a95cd59ba2cd67991b6f722b3 Mon Sep 17 00:00:00 2001
From: matt mooney <mfm@muteddisk.com>
Date: Sun, 24 Oct 2010 18:16:58 +0200
Subject: [PATCH 06/13] i2c: Change to new flag variable

Replace EXTRA_CFLAGS with ccflags-y.

Signed-off-by: matt mooney <mfm@muteddisk.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
 drivers/i2c/Makefile        | 4 +---
 drivers/i2c/algos/Makefile  | 4 +---
 drivers/i2c/busses/Makefile | 4 +---
 drivers/i2c/muxes/Makefile  | 4 +---
 4 files changed, 4 insertions(+), 12 deletions(-)

diff --git a/drivers/i2c/Makefile b/drivers/i2c/Makefile
index c00fd66388f5..23ac61e2db39 100644
--- a/drivers/i2c/Makefile
+++ b/drivers/i2c/Makefile
@@ -9,6 +9,4 @@ obj-$(CONFIG_I2C_CHARDEV)	+= i2c-dev.o
 obj-$(CONFIG_I2C_MUX)		+= i2c-mux.o
 obj-y				+= algos/ busses/ muxes/
 
-ifeq ($(CONFIG_I2C_DEBUG_CORE),y)
-EXTRA_CFLAGS += -DDEBUG
-endif
+ccflags-$(CONFIG_I2C_DEBUG_CORE) := -DDEBUG
diff --git a/drivers/i2c/algos/Makefile b/drivers/i2c/algos/Makefile
index 18b3e962ec09..215303f60d61 100644
--- a/drivers/i2c/algos/Makefile
+++ b/drivers/i2c/algos/Makefile
@@ -6,6 +6,4 @@ obj-$(CONFIG_I2C_ALGOBIT)	+= i2c-algo-bit.o
 obj-$(CONFIG_I2C_ALGOPCF)	+= i2c-algo-pcf.o
 obj-$(CONFIG_I2C_ALGOPCA)	+= i2c-algo-pca.o
 
-ifeq ($(CONFIG_I2C_DEBUG_ALGO),y)
-EXTRA_CFLAGS += -DDEBUG
-endif
+ccflags-$(CONFIG_I2C_DEBUG_ALGO) := -DDEBUG
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index c3ef49230cba..033ad413f328 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -76,6 +76,4 @@ obj-$(CONFIG_I2C_STUB)		+= i2c-stub.o
 obj-$(CONFIG_SCx200_ACB)	+= scx200_acb.o
 obj-$(CONFIG_SCx200_I2C)	+= scx200_i2c.o
 
-ifeq ($(CONFIG_I2C_DEBUG_BUS),y)
-EXTRA_CFLAGS += -DDEBUG
-endif
+ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index bd83b5274815..6f497862bdc5 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -3,6 +3,4 @@
 
 obj-$(CONFIG_I2C_MUX_PCA954x)	+= pca954x.o
 
-ifeq ($(CONFIG_I2C_DEBUG_BUS),y)
-EXTRA_CFLAGS += -DDEBUG
-endif
+ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG

From 9cb2c2726e9ae212ccaeecd3eaadcd8d49ac7400 Mon Sep 17 00:00:00 2001
From: Julia Lawall <julia@diku.dk>
Date: Sun, 24 Oct 2010 18:16:58 +0200
Subject: [PATCH 07/13] i2c-amd8111: Add proper error handling

The functions the functions amd_ec_wait_write and amd_ec_wait_read have an
unsigned return type, but return a negative constant to indicate an error
condition.

A sematic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@exists@
identifier f;
constant C;
@@

 unsigned f(...)
 { <+...
*  return -C;
 ...+> }
// </smpl>

Fixing amd_ec_wait_write and amd_ec_wait_read leads to the need to adjust
the return type of the functions amd_ec_write and amd_ec_read, which are
the only functions that call amd_ec_wait_write and amd_ec_wait_read.
amd_ec_write and amd_ec_read, in turn, are only called from within the
function amd8111_access, which already returns a signed typed value.  Each
of the calls to amd_ec_write and amd_ec_read are updated using the
following semantic patch:

// <smpl>
@@
@@

+ status = amd_ec_write
- amd_ec_write
  (...);
+ if (status) return status;

@@
@@

+ status = amd_ec_read
- amd_ec_read
  (...);
+ if (status) return status;
// </smpl>

The patch also adds the declaration of the status variable.

Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
 drivers/i2c/busses/i2c-amd8111.c | 163 +++++++++++++++++++++----------
 1 file changed, 113 insertions(+), 50 deletions(-)

diff --git a/drivers/i2c/busses/i2c-amd8111.c b/drivers/i2c/busses/i2c-amd8111.c
index af1e5e254b7b..6b6a6b1d7025 100644
--- a/drivers/i2c/busses/i2c-amd8111.c
+++ b/drivers/i2c/busses/i2c-amd8111.c
@@ -69,7 +69,7 @@ static struct pci_driver amd8111_driver;
  * ACPI 2.0 chapter 13 access of registers of the EC
  */
 
-static unsigned int amd_ec_wait_write(struct amd_smbus *smbus)
+static int amd_ec_wait_write(struct amd_smbus *smbus)
 {
 	int timeout = 500;
 
@@ -85,7 +85,7 @@ static unsigned int amd_ec_wait_write(struct amd_smbus *smbus)
 	return 0;
 }
 
-static unsigned int amd_ec_wait_read(struct amd_smbus *smbus)
+static int amd_ec_wait_read(struct amd_smbus *smbus)
 {
 	int timeout = 500;
 
@@ -101,7 +101,7 @@ static unsigned int amd_ec_wait_read(struct amd_smbus *smbus)
 	return 0;
 }
 
-static unsigned int amd_ec_read(struct amd_smbus *smbus, unsigned char address,
+static int amd_ec_read(struct amd_smbus *smbus, unsigned char address,
 		unsigned char *data)
 {
 	int status;
@@ -124,7 +124,7 @@ static unsigned int amd_ec_read(struct amd_smbus *smbus, unsigned char address,
 	return 0;
 }
 
-static unsigned int amd_ec_write(struct amd_smbus *smbus, unsigned char address,
+static int amd_ec_write(struct amd_smbus *smbus, unsigned char address,
 		unsigned char data)
 {
 	int status;
@@ -196,7 +196,7 @@ static s32 amd8111_access(struct i2c_adapter * adap, u16 addr,
 {
 	struct amd_smbus *smbus = adap->algo_data;
 	unsigned char protocol, len, pec, temp[2];
-	int i;
+	int i, status;
 
 	protocol = (read_write == I2C_SMBUS_READ) ? AMD_SMB_PRTCL_READ
 						  : AMD_SMB_PRTCL_WRITE;
@@ -209,38 +209,62 @@ static s32 amd8111_access(struct i2c_adapter * adap, u16 addr,
 			break;
 
 		case I2C_SMBUS_BYTE:
-			if (read_write == I2C_SMBUS_WRITE)
-				amd_ec_write(smbus, AMD_SMB_CMD, command);
+			if (read_write == I2C_SMBUS_WRITE) {
+				status = amd_ec_write(smbus, AMD_SMB_CMD,
+						      command);
+				if (status)
+					return status;
+			}
 			protocol |= AMD_SMB_PRTCL_BYTE;
 			break;
 
 		case I2C_SMBUS_BYTE_DATA:
-			amd_ec_write(smbus, AMD_SMB_CMD, command);
-			if (read_write == I2C_SMBUS_WRITE)
-				amd_ec_write(smbus, AMD_SMB_DATA, data->byte);
+			status = amd_ec_write(smbus, AMD_SMB_CMD, command);
+			if (status)
+				return status;
+			if (read_write == I2C_SMBUS_WRITE) {
+				status = amd_ec_write(smbus, AMD_SMB_DATA,
+						      data->byte);
+				if (status)
+					return status;
+			}
 			protocol |= AMD_SMB_PRTCL_BYTE_DATA;
 			break;
 
 		case I2C_SMBUS_WORD_DATA:
-			amd_ec_write(smbus, AMD_SMB_CMD, command);
+			status = amd_ec_write(smbus, AMD_SMB_CMD, command);
+			if (status)
+				return status;
 			if (read_write == I2C_SMBUS_WRITE) {
-				amd_ec_write(smbus, AMD_SMB_DATA,
-					     data->word & 0xff);
-				amd_ec_write(smbus, AMD_SMB_DATA + 1,
-					     data->word >> 8);
+				status = amd_ec_write(smbus, AMD_SMB_DATA,
+						      data->word & 0xff);
+				if (status)
+					return status;
+				status = amd_ec_write(smbus, AMD_SMB_DATA + 1,
+						      data->word >> 8);
+				if (status)
+					return status;
 			}
 			protocol |= AMD_SMB_PRTCL_WORD_DATA | pec;
 			break;
 
 		case I2C_SMBUS_BLOCK_DATA:
-			amd_ec_write(smbus, AMD_SMB_CMD, command);
+			status = amd_ec_write(smbus, AMD_SMB_CMD, command);
+			if (status)
+				return status;
 			if (read_write == I2C_SMBUS_WRITE) {
 				len = min_t(u8, data->block[0],
 					    I2C_SMBUS_BLOCK_MAX);
-				amd_ec_write(smbus, AMD_SMB_BCNT, len);
-				for (i = 0; i < len; i++)
-					amd_ec_write(smbus, AMD_SMB_DATA + i,
-						     data->block[i + 1]);
+				status = amd_ec_write(smbus, AMD_SMB_BCNT, len);
+				if (status)
+					return status;
+				for (i = 0; i < len; i++) {
+					status =
+					  amd_ec_write(smbus, AMD_SMB_DATA + i,
+						       data->block[i + 1]);
+					if (status)
+						return status;
+				}
 			}
 			protocol |= AMD_SMB_PRTCL_BLOCK_DATA | pec;
 			break;
@@ -248,19 +272,35 @@ static s32 amd8111_access(struct i2c_adapter * adap, u16 addr,
 		case I2C_SMBUS_I2C_BLOCK_DATA:
 			len = min_t(u8, data->block[0],
 				    I2C_SMBUS_BLOCK_MAX);
-			amd_ec_write(smbus, AMD_SMB_CMD, command);
-			amd_ec_write(smbus, AMD_SMB_BCNT, len);
+			status = amd_ec_write(smbus, AMD_SMB_CMD, command);
+			if (status)
+				return status;
+			status = amd_ec_write(smbus, AMD_SMB_BCNT, len);
+			if (status)
+				return status;
 			if (read_write == I2C_SMBUS_WRITE)
-				for (i = 0; i < len; i++)
-					amd_ec_write(smbus, AMD_SMB_DATA + i,
-						     data->block[i + 1]);
+				for (i = 0; i < len; i++) {
+					status =
+					  amd_ec_write(smbus, AMD_SMB_DATA + i,
+						       data->block[i + 1]);
+					if (status)
+						return status;
+				}
 			protocol |= AMD_SMB_PRTCL_I2C_BLOCK_DATA;
 			break;
 
 		case I2C_SMBUS_PROC_CALL:
-			amd_ec_write(smbus, AMD_SMB_CMD, command);
-			amd_ec_write(smbus, AMD_SMB_DATA, data->word & 0xff);
-			amd_ec_write(smbus, AMD_SMB_DATA + 1, data->word >> 8);
+			status = amd_ec_write(smbus, AMD_SMB_CMD, command);
+			if (status)
+				return status;
+			status = amd_ec_write(smbus, AMD_SMB_DATA,
+					      data->word & 0xff);
+			if (status)
+				return status;
+			status = amd_ec_write(smbus, AMD_SMB_DATA + 1,
+					      data->word >> 8);
+			if (status)
+				return status;
 			protocol = AMD_SMB_PRTCL_PROC_CALL | pec;
 			read_write = I2C_SMBUS_READ;
 			break;
@@ -268,11 +308,18 @@ static s32 amd8111_access(struct i2c_adapter * adap, u16 addr,
 		case I2C_SMBUS_BLOCK_PROC_CALL:
 			len = min_t(u8, data->block[0],
 				    I2C_SMBUS_BLOCK_MAX - 1);
-			amd_ec_write(smbus, AMD_SMB_CMD, command);
-			amd_ec_write(smbus, AMD_SMB_BCNT, len);
-			for (i = 0; i < len; i++)
-				amd_ec_write(smbus, AMD_SMB_DATA + i,
-					     data->block[i + 1]);
+			status = amd_ec_write(smbus, AMD_SMB_CMD, command);
+			if (status)
+				return status;
+			status = amd_ec_write(smbus, AMD_SMB_BCNT, len);
+			if (status)
+				return status;
+			for (i = 0; i < len; i++) {
+				status = amd_ec_write(smbus, AMD_SMB_DATA + i,
+						      data->block[i + 1]);
+				if (status)
+					return status;
+			}
 			protocol = AMD_SMB_PRTCL_BLOCK_PROC_CALL | pec;
 			read_write = I2C_SMBUS_READ;
 			break;
@@ -282,24 +329,29 @@ static s32 amd8111_access(struct i2c_adapter * adap, u16 addr,
 			return -EOPNOTSUPP;
 	}
 
-	amd_ec_write(smbus, AMD_SMB_ADDR, addr << 1);
-	amd_ec_write(smbus, AMD_SMB_PRTCL, protocol);
+	status = amd_ec_write(smbus, AMD_SMB_ADDR, addr << 1);
+	if (status)
+		return status;
+	status = amd_ec_write(smbus, AMD_SMB_PRTCL, protocol);
+	if (status)
+		return status;
 
-	/* FIXME this discards status from ec_read(); so temp[0] will
-	 * hold stack garbage ... the rest of this routine will act
-	 * nonsensically.  Ignored ec_write() status might explain
-	 * some such failures...
-	 */
-	amd_ec_read(smbus, AMD_SMB_STS, temp + 0);
+	status = amd_ec_read(smbus, AMD_SMB_STS, temp + 0);
+	if (status)
+		return status;
 
 	if (~temp[0] & AMD_SMB_STS_DONE) {
 		udelay(500);
-		amd_ec_read(smbus, AMD_SMB_STS, temp + 0);
+		status = amd_ec_read(smbus, AMD_SMB_STS, temp + 0);
+		if (status)
+			return status;
 	}
 
 	if (~temp[0] & AMD_SMB_STS_DONE) {
 		msleep(1);
-		amd_ec_read(smbus, AMD_SMB_STS, temp + 0);
+		status = amd_ec_read(smbus, AMD_SMB_STS, temp + 0);
+		if (status)
+			return status;
 	}
 
 	if ((~temp[0] & AMD_SMB_STS_DONE) || (temp[0] & AMD_SMB_STS_STATUS))
@@ -311,24 +363,35 @@ static s32 amd8111_access(struct i2c_adapter * adap, u16 addr,
 	switch (size) {
 		case I2C_SMBUS_BYTE:
 		case I2C_SMBUS_BYTE_DATA:
-			amd_ec_read(smbus, AMD_SMB_DATA, &data->byte);
+			status = amd_ec_read(smbus, AMD_SMB_DATA, &data->byte);
+			if (status)
+				return status;
 			break;
 
 		case I2C_SMBUS_WORD_DATA:
 		case I2C_SMBUS_PROC_CALL:
-			amd_ec_read(smbus, AMD_SMB_DATA, temp + 0);
-			amd_ec_read(smbus, AMD_SMB_DATA + 1, temp + 1);
+			status = amd_ec_read(smbus, AMD_SMB_DATA, temp + 0);
+			if (status)
+				return status;
+			status = amd_ec_read(smbus, AMD_SMB_DATA + 1, temp + 1);
+			if (status)
+				return status;
 			data->word = (temp[1] << 8) | temp[0];
 			break;
 
 		case I2C_SMBUS_BLOCK_DATA:
 		case I2C_SMBUS_BLOCK_PROC_CALL:
-			amd_ec_read(smbus, AMD_SMB_BCNT, &len);
+			status = amd_ec_read(smbus, AMD_SMB_BCNT, &len);
+			if (status)
+				return status;
 			len = min_t(u8, len, I2C_SMBUS_BLOCK_MAX);
 		case I2C_SMBUS_I2C_BLOCK_DATA:
-			for (i = 0; i < len; i++)
-				amd_ec_read(smbus, AMD_SMB_DATA + i,
-					    data->block + i + 1);
+			for (i = 0; i < len; i++) {
+				status = amd_ec_read(smbus, AMD_SMB_DATA + i,
+						     data->block + i + 1);
+				if (status)
+					return status;
+			}
 			data->block[0] = len;
 			break;
 	}

From d57558d0f3b41bb260aaa327150d49f1810461f5 Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Sun, 24 Oct 2010 18:16:58 +0200
Subject: [PATCH 08/13] i2c: Discard warning message on device instantiation
 from user-space

The "new_device" sysfs interface has been there for quite some time
now, nobody complained about it so it must be good enough. Time to
remove the warning and call it stable.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Acked-by: Michael Lawnick <ml.lawnick@gmx.de>
---
 drivers/i2c/i2c-core.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 40e563de0508..bdadfaf3fe10 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -683,8 +683,6 @@ i2c_sysfs_new_device(struct device *dev, struct device_attribute *attr,
 	char *blank, end;
 	int res;
 
-	dev_warn(dev, "The new_device interface is still experimental "
-		 "and may change in a near future\n");
 	memset(&info, 0, sizeof(struct i2c_board_info));
 
 	blank = strchr(buf, ' ');

From 51b54ba9bb16b9fc28ec88006778d330af00bf8b Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Sun, 24 Oct 2010 18:16:58 +0200
Subject: [PATCH 09/13] i2c: Optimize function i2c_detect()

Check the class flags before allocating the temporary i2c_client
structure, to avoid allocating it when we don't need it.

Also optimize the inner loop a bit.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
---
 drivers/i2c/i2c-core.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index bdadfaf3fe10..d231f683f576 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1508,26 +1508,25 @@ static int i2c_detect(struct i2c_adapter *adapter, struct i2c_driver *driver)
 	if (!driver->detect || !address_list)
 		return 0;
 
+	/* Stop here if the classes do not match */
+	if (!(adapter->class & driver->class))
+		return 0;
+
 	/* Set up a temporary client to help detect callback */
 	temp_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL);
 	if (!temp_client)
 		return -ENOMEM;
 	temp_client->adapter = adapter;
 
-	/* Stop here if the classes do not match */
-	if (!(adapter->class & driver->class))
-		goto exit_free;
-
 	for (i = 0; address_list[i] != I2C_CLIENT_END; i += 1) {
 		dev_dbg(&adapter->dev, "found normal entry for adapter %d, "
 			"addr 0x%02x\n", adap_id, address_list[i]);
 		temp_client->addr = address_list[i];
 		err = i2c_detect_address(temp_client, driver);
-		if (err)
-			goto exit_free;
+		if (unlikely(err))
+			break;
 	}
 
- exit_free:
 	kfree(temp_client);
 	return err;
 }

From ae63b13bbeca7f8915c555663f8789a531611e4b Mon Sep 17 00:00:00 2001
From: Guenter Roeck <guenter.roeck@ericsson.com>
Date: Sun, 24 Oct 2010 18:16:58 +0200
Subject: [PATCH 10/13] i2c/mux: Driver for PCA9541 I2C Master Selector

This patch adds support for PCA9541, an I2C Bus Master Selector.
The driver is modeled as single channel I2C Multiplexer to be able to utilize
the I2C multiplexer framework.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Reviewed-by: Tom Grennan <tom.grennan@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
---
 drivers/i2c/muxes/Kconfig   |  10 +
 drivers/i2c/muxes/Makefile  |   1 +
 drivers/i2c/muxes/pca9541.c | 411 ++++++++++++++++++++++++++++++++++++
 3 files changed, 422 insertions(+)
 create mode 100644 drivers/i2c/muxes/pca9541.c

diff --git a/drivers/i2c/muxes/Kconfig b/drivers/i2c/muxes/Kconfig
index 4c9a99c4fcb0..4d91d80bfd23 100644
--- a/drivers/i2c/muxes/Kconfig
+++ b/drivers/i2c/muxes/Kconfig
@@ -5,6 +5,16 @@
 menu "Multiplexer I2C Chip support"
 	depends on I2C_MUX
 
+config I2C_MUX_PCA9541
+	tristate "NXP PCA9541 I2C Master Selector"
+	depends on EXPERIMENTAL
+	help
+	  If you say yes here you get support for the NXP PCA9541
+	  I2C Master Selector.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called pca9541.
+
 config I2C_MUX_PCA954x
 	tristate "Philips PCA954x I2C Mux/switches"
 	depends on EXPERIMENTAL
diff --git a/drivers/i2c/muxes/Makefile b/drivers/i2c/muxes/Makefile
index 6f497862bdc5..d743806d9b42 100644
--- a/drivers/i2c/muxes/Makefile
+++ b/drivers/i2c/muxes/Makefile
@@ -1,6 +1,7 @@
 #
 # Makefile for multiplexer I2C chip drivers.
 
+obj-$(CONFIG_I2C_MUX_PCA9541)	+= pca9541.o
 obj-$(CONFIG_I2C_MUX_PCA954x)	+= pca954x.o
 
 ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/muxes/pca9541.c b/drivers/i2c/muxes/pca9541.c
new file mode 100644
index 000000000000..ed699c5aa79d
--- /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");

From 5ce914a8965031a4de503235eb9e0d33ff294fa8 Mon Sep 17 00:00:00 2001
From: Guenter Roeck <guenter.roeck@ericsson.com>
Date: Sun, 24 Oct 2010 18:16:59 +0200
Subject: [PATCH 11/13] MAINTAINERS: Add maintainer for PCA9541 I2C bus master
 selector driver

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
 MAINTAINERS | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 494e1a07366a..62437773cac4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4532,6 +4532,12 @@ S:	Maintained
 F:	drivers/leds/leds-pca9532.c
 F:	include/linux/leds-pca9532.h
 
+PCA9541 I2C BUS MASTER SELECTOR DRIVER
+M:	Guenter Roeck <guenter.roeck@ericsson.com>
+L:	linux-i2c@vger.kernel.org
+S:	Maintained
+F:	drivers/i2c/muxes/pca9541.c
+
 PCA9564/PCA9665 I2C BUS DRIVER
 M:	Wolfram Sang <w.sang@pengutronix.de>
 L:	linux-i2c@vger.kernel.org

From db79f2a1d259a9026241dd0f192c20d6264d5afa Mon Sep 17 00:00:00 2001
From: Guenter Roeck <guenter.roeck@ericsson.com>
Date: Sun, 24 Oct 2010 18:16:59 +0200
Subject: [PATCH 12/13] i2c/pca954x: Remove __devinit and __devexit from probe
 and remove functions

The underlying I2C adapter may or may not be present when this driver
gets initialized, and may disappear later, so there is no safe time at
which the probe and remove functions can be discarded.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
 drivers/i2c/muxes/pca954x.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/muxes/pca954x.c b/drivers/i2c/muxes/pca954x.c
index 6f9accf3189d..54e1ce73534b 100644
--- a/drivers/i2c/muxes/pca954x.c
+++ b/drivers/i2c/muxes/pca954x.c
@@ -181,8 +181,8 @@ static int pca954x_deselect_mux(struct i2c_adapter *adap,
 /*
  * I2C init/probing/exit functions
  */
-static int __devinit pca954x_probe(struct i2c_client *client,
-				   const struct i2c_device_id *id)
+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;
@@ -255,7 +255,7 @@ err:
 	return ret;
 }
 
-static int __devexit pca954x_remove(struct i2c_client *client)
+static int pca954x_remove(struct i2c_client *client)
 {
 	struct pca954x *data = i2c_get_clientdata(client);
 	const struct chip_desc *chip = &chips[data->type];
@@ -279,7 +279,7 @@ static struct i2c_driver pca954x_driver = {
 		.owner	= THIS_MODULE,
 	},
 	.probe		= pca954x_probe,
-	.remove		= __devexit_p(pca954x_remove),
+	.remove		= pca954x_remove,
 	.id_table	= pca954x_id,
 };
 

From bf5d95c82692ead9ba7876af73dac2edcc8a6191 Mon Sep 17 00:00:00 2001
From: Jean Delvare <khali@linux-fr.org>
Date: Sun, 24 Oct 2010 18:16:59 +0200
Subject: [PATCH 13/13] i2c-viapro: Don't log nacks

Transactions not acked can happen every now and then, in particular
during device detection, and various transaction types can be used for
this purpose. So stop logging this event, except when debugging is
enabled. This is what other similar drivers (e.g. i2c-i801 or
i2c-piix4) do.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
---
 drivers/i2c/busses/i2c-viapro.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-viapro.c b/drivers/i2c/busses/i2c-viapro.c
index 4c6fff5f330d..0b012f1f8ac5 100644
--- a/drivers/i2c/busses/i2c-viapro.c
+++ b/drivers/i2c/busses/i2c-viapro.c
@@ -185,14 +185,8 @@ static int vt596_transaction(u8 size)
 	}
 
 	if (temp & 0x04) {
-		int read = inb_p(SMBHSTADD) & 0x01;
 		result = -ENXIO;
-		/* The quick and receive byte commands are used to probe
-		   for chips, so errors are expected, and we don't want
-		   to frighten the user. */
-		if (!((size == VT596_QUICK && !read) ||
-		      (size == VT596_BYTE && read)))
-			dev_err(&vt596_adapter.dev, "Transaction error!\n");
+		dev_dbg(&vt596_adapter.dev, "No response\n");
 	}
 
 	/* Resetting status register */