[PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Jean Delvare]

The i2c-amd756-s4882 and i2c-nforce2-s4985 muxing pseudo-drivers were
written at a time when the i2c core did not support muxing. They are
essentially board-specific hacks. If we had to add support for these
boards today, we would implement it in a completely different way.

These Tyan server boards are 18 years old by now, so I very much doubt
any of these is still running today. So let's just drop this clumsy
code. If anyone really still needs this support and complains, I'll
rewrite it in a proper way on top of i2c-mux.

This also fixes the following warnings:
drivers/i2c/busses/i2c-amd756.c:286:20: warning: symbol 'amd756_smbus' was not declared. Should it be static?
drivers/i2c/busses/i2c-nforce2.c:123:20: warning: symbol 'nforce2_smbus' was not declared. Should it be static?

Signed-off-by: Jean Delvare <jdelvare@suse.de>
Acked-by: Nick Desaulniers <ndesaulniers@google.com>
Cc: Andi Shyti <andi.shyti@kernel.org>
---
Changes since v1:
 * Added Nick's ack.
 * Rebased on top of v6.6-rc3.

 MAINTAINERS                            |    2 
 drivers/i2c/busses/Kconfig             |   26 ---
 drivers/i2c/busses/Makefile            |    2 
 drivers/i2c/busses/i2c-amd756-s4882.c  |  245 ---------------------------------
 drivers/i2c/busses/i2c-amd756.c        |    4 
 drivers/i2c/busses/i2c-nforce2-s4985.c |  240 --------------------------------
 drivers/i2c/busses/i2c-nforce2.c       |   16 --
 7 files changed, 1 insertion(+), 534 deletions(-)

--- linux-6.6-rc3.orig/MAINTAINERS
+++ linux-6.6-rc3/MAINTAINERS
@@ -9871,12 +9871,10 @@ F:	Documentation/i2c/busses/i2c-viapro.r
 F:	drivers/i2c/busses/i2c-ali1535.c
 F:	drivers/i2c/busses/i2c-ali1563.c
 F:	drivers/i2c/busses/i2c-ali15x3.c
-F:	drivers/i2c/busses/i2c-amd756-s4882.c
 F:	drivers/i2c/busses/i2c-amd756.c
 F:	drivers/i2c/busses/i2c-amd8111.c
 F:	drivers/i2c/busses/i2c-i801.c
 F:	drivers/i2c/busses/i2c-isch.c
-F:	drivers/i2c/busses/i2c-nforce2-s4985.c
 F:	drivers/i2c/busses/i2c-nforce2.c
 F:	drivers/i2c/busses/i2c-piix4.c
 F:	drivers/i2c/busses/i2c-sis5595.c
--- linux-6.6-rc3.orig/drivers/i2c/busses/Kconfig
+++ linux-6.6-rc3/drivers/i2c/busses/Kconfig
@@ -62,19 +62,6 @@ config I2C_AMD756
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-amd756.
 
-config I2C_AMD756_S4882
-	tristate "SMBus multiplexing on the Tyan S4882"
-	depends on I2C_AMD756 && X86
-	help
-	  Enabling this option will add specific SMBus support for the Tyan
-	  S4882 motherboard.  On this 4-CPU board, the SMBus is multiplexed
-	  over 8 different channels, where the various memory module EEPROMs
-	  and temperature sensors live.  Saying yes here will give you access
-	  to these in addition to the trunk.
-
-	  This driver can also be built as a module.  If so, the module
-	  will be called i2c-amd756-s4882.
-
 config I2C_AMD8111
 	tristate "AMD 8111"
 	depends on PCI
@@ -239,19 +226,6 @@ config I2C_NFORCE2
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-nforce2.
 
-config I2C_NFORCE2_S4985
-	tristate "SMBus multiplexing on the Tyan S4985"
-	depends on I2C_NFORCE2 && X86
-	help
-	  Enabling this option will add specific SMBus support for the Tyan
-	  S4985 motherboard.  On this 4-CPU board, the SMBus is multiplexed
-	  over 4 different channels, where the various memory module EEPROMs
-	  live.  Saying yes here will give you access to these in addition
-	  to the trunk.
-
-	  This driver can also be built as a module.  If so, the module
-	  will be called i2c-nforce2-s4985.
-
 config I2C_NVIDIA_GPU
 	tristate "NVIDIA GPU I2C controller"
 	depends on PCI
--- linux-6.6-rc3.orig/drivers/i2c/busses/Makefile
+++ linux-6.6-rc3/drivers/i2c/busses/Makefile
@@ -14,14 +14,12 @@ obj-$(CONFIG_I2C_ALI1535)	+= i2c-ali1535
 obj-$(CONFIG_I2C_ALI1563)	+= i2c-ali1563.o
 obj-$(CONFIG_I2C_ALI15X3)	+= i2c-ali15x3.o
 obj-$(CONFIG_I2C_AMD756)	+= i2c-amd756.o
-obj-$(CONFIG_I2C_AMD756_S4882)	+= i2c-amd756-s4882.o
 obj-$(CONFIG_I2C_AMD8111)	+= i2c-amd8111.o
 obj-$(CONFIG_I2C_CHT_WC)	+= i2c-cht-wc.o
 obj-$(CONFIG_I2C_I801)		+= i2c-i801.o
 obj-$(CONFIG_I2C_ISCH)		+= i2c-isch.o
 obj-$(CONFIG_I2C_ISMT)		+= i2c-ismt.o
 obj-$(CONFIG_I2C_NFORCE2)	+= i2c-nforce2.o
-obj-$(CONFIG_I2C_NFORCE2_S4985)	+= i2c-nforce2-s4985.o
 obj-$(CONFIG_I2C_NVIDIA_GPU)	+= i2c-nvidia-gpu.o
 obj-$(CONFIG_I2C_PIIX4)		+= i2c-piix4.o
 obj-$(CONFIG_I2C_SIS5595)	+= i2c-sis5595.o
--- linux-6.6-rc3.orig/drivers/i2c/busses/i2c-amd756-s4882.c
+++ /dev/null
@@ -1,245 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * i2c-amd756-s4882.c - i2c-amd756 extras for the Tyan S4882 motherboard
- *
- * Copyright (C) 2004, 2008 Jean Delvare <jdelvare@suse.de>
- */
- 
-/*
- * We select the channels by sending commands to the Philips
- * PCA9556 chip at I2C address 0x18. The main adapter is used for
- * the non-multiplexed part of the bus, and 4 virtual adapters
- * are defined for the multiplexed addresses: 0x50-0x53 (memory
- * module EEPROM) located on channels 1-4, and 0x4c (LM63)
- * located on multiplexed channels 0 and 5-7. We define one
- * virtual adapter per CPU, which corresponds to two multiplexed
- * channels:
- *   CPU0: virtual adapter 1, channels 1 and 0
- *   CPU1: virtual adapter 2, channels 2 and 5
- *   CPU2: virtual adapter 3, channels 3 and 6
- *   CPU3: virtual adapter 4, channels 4 and 7
- */
-
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/init.h>
-#include <linux/i2c.h>
-#include <linux/mutex.h>
-
-extern struct i2c_adapter amd756_smbus;
-
-static struct i2c_adapter *s4882_adapter;
-static struct i2c_algorithm *s4882_algo;
-
-/* Wrapper access functions for multiplexed SMBus */
-static DEFINE_MUTEX(amd756_lock);
-
-static s32 amd756_access_virt0(struct i2c_adapter * adap, u16 addr,
-			       unsigned short flags, char read_write,
-			       u8 command, int size,
-			       union i2c_smbus_data * data)
-{
-	int error;
-
-	/* We exclude the multiplexed addresses */
-	if (addr == 0x4c || (addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
-	 || addr == 0x18)
-		return -ENXIO;
-
-	mutex_lock(&amd756_lock);
-
-	error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
-					      command, size, data);
-
-	mutex_unlock(&amd756_lock);
-
-	return error;
-}
-
-/* We remember the last used channels combination so as to only switch
-   channels when it is really needed. This greatly reduces the SMBus
-   overhead, but also assumes that nobody will be writing to the PCA9556
-   in our back. */
-static u8 last_channels;
-
-static inline s32 amd756_access_channel(struct i2c_adapter * adap, u16 addr,
-					unsigned short flags, char read_write,
-					u8 command, int size,
-					union i2c_smbus_data * data,
-					u8 channels)
-{
-	int error;
-
-	/* We exclude the non-multiplexed addresses */
-	if (addr != 0x4c && (addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
-		return -ENXIO;
-
-	mutex_lock(&amd756_lock);
-
-	if (last_channels != channels) {
-		union i2c_smbus_data mplxdata;
-		mplxdata.byte = channels;
-
-		error = amd756_smbus.algo->smbus_xfer(adap, 0x18, 0,
-						      I2C_SMBUS_WRITE, 0x01,
-						      I2C_SMBUS_BYTE_DATA,
-						      &mplxdata);
-		if (error)
-			goto UNLOCK;
-		last_channels = channels;
-	}
-	error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
-					      command, size, data);
-
-UNLOCK:
-	mutex_unlock(&amd756_lock);
-	return error;
-}
-
-static s32 amd756_access_virt1(struct i2c_adapter * adap, u16 addr,
-			       unsigned short flags, char read_write,
-			       u8 command, int size,
-			       union i2c_smbus_data * data)
-{
-	/* CPU0: channels 1 and 0 enabled */
-	return amd756_access_channel(adap, addr, flags, read_write, command,
-				     size, data, 0x03);
-}
-
-static s32 amd756_access_virt2(struct i2c_adapter * adap, u16 addr,
-			       unsigned short flags, char read_write,
-			       u8 command, int size,
-			       union i2c_smbus_data * data)
-{
-	/* CPU1: channels 2 and 5 enabled */
-	return amd756_access_channel(adap, addr, flags, read_write, command,
-				     size, data, 0x24);
-}
-
-static s32 amd756_access_virt3(struct i2c_adapter * adap, u16 addr,
-			       unsigned short flags, char read_write,
-			       u8 command, int size,
-			       union i2c_smbus_data * data)
-{
-	/* CPU2: channels 3 and 6 enabled */
-	return amd756_access_channel(adap, addr, flags, read_write, command,
-				     size, data, 0x48);
-}
-
-static s32 amd756_access_virt4(struct i2c_adapter * adap, u16 addr,
-			       unsigned short flags, char read_write,
-			       u8 command, int size,
-			       union i2c_smbus_data * data)
-{
-	/* CPU3: channels 4 and 7 enabled */
-	return amd756_access_channel(adap, addr, flags, read_write, command,
-				     size, data, 0x90);
-}
-
-static int __init amd756_s4882_init(void)
-{
-	int i, error;
-	union i2c_smbus_data ioconfig;
-
-	if (!amd756_smbus.dev.parent)
-		return -ENODEV;
-
-	/* Configure the PCA9556 multiplexer */
-	ioconfig.byte = 0x00; /* All I/O to output mode */
-	error = i2c_smbus_xfer(&amd756_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
-			       I2C_SMBUS_BYTE_DATA, &ioconfig);
-	if (error) {
-		dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
-		error = -EIO;
-		goto ERROR0;
-	}
-
-	/* Unregister physical bus */
-	i2c_del_adapter(&amd756_smbus);
-
-	printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n");
-	/* Define the 5 virtual adapters and algorithms structures */
-	if (!(s4882_adapter = kcalloc(5, sizeof(struct i2c_adapter),
-				      GFP_KERNEL))) {
-		error = -ENOMEM;
-		goto ERROR1;
-	}
-	if (!(s4882_algo = kcalloc(5, sizeof(struct i2c_algorithm),
-				   GFP_KERNEL))) {
-		error = -ENOMEM;
-		goto ERROR2;
-	}
-
-	/* Fill in the new structures */
-	s4882_algo[0] = *(amd756_smbus.algo);
-	s4882_algo[0].smbus_xfer = amd756_access_virt0;
-	s4882_adapter[0] = amd756_smbus;
-	s4882_adapter[0].algo = s4882_algo;
-	s4882_adapter[0].dev.parent = amd756_smbus.dev.parent;
-	for (i = 1; i < 5; i++) {
-		s4882_algo[i] = *(amd756_smbus.algo);
-		s4882_adapter[i] = amd756_smbus;
-		snprintf(s4882_adapter[i].name, sizeof(s4882_adapter[i].name),
-			 "SMBus 8111 adapter (CPU%d)", i-1);
-		s4882_adapter[i].algo = s4882_algo+i;
-		s4882_adapter[i].dev.parent = amd756_smbus.dev.parent;
-	}
-	s4882_algo[1].smbus_xfer = amd756_access_virt1;
-	s4882_algo[2].smbus_xfer = amd756_access_virt2;
-	s4882_algo[3].smbus_xfer = amd756_access_virt3;
-	s4882_algo[4].smbus_xfer = amd756_access_virt4;
-
-	/* Register virtual adapters */
-	for (i = 0; i < 5; i++) {
-		error = i2c_add_adapter(s4882_adapter+i);
-		if (error) {
-			printk(KERN_ERR "i2c-amd756-s4882: "
-			       "Virtual adapter %d registration "
-			       "failed, module not inserted\n", i);
-			for (i--; i >= 0; i--)
-				i2c_del_adapter(s4882_adapter+i);
-			goto ERROR3;
-		}
-	}
-
-	return 0;
-
-ERROR3:
-	kfree(s4882_algo);
-	s4882_algo = NULL;
-ERROR2:
-	kfree(s4882_adapter);
-	s4882_adapter = NULL;
-ERROR1:
-	/* Restore physical bus */
-	i2c_add_adapter(&amd756_smbus);
-ERROR0:
-	return error;
-}
-
-static void __exit amd756_s4882_exit(void)
-{
-	if (s4882_adapter) {
-		int i;
-
-		for (i = 0; i < 5; i++)
-			i2c_del_adapter(s4882_adapter+i);
-		kfree(s4882_adapter);
-		s4882_adapter = NULL;
-	}
-	kfree(s4882_algo);
-	s4882_algo = NULL;
-
-	/* Restore physical bus */
-	if (i2c_add_adapter(&amd756_smbus))
-		printk(KERN_ERR "i2c-amd756-s4882: "
-		       "Physical bus restoration failed\n");
-}
-
-MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
-MODULE_DESCRIPTION("S4882 SMBus multiplexing");
-MODULE_LICENSE("GPL");
-
-module_init(amd756_s4882_init);
-module_exit(amd756_s4882_exit);
--- linux-6.6-rc3.orig/drivers/i2c/busses/i2c-amd756.c
+++ linux-6.6-rc3/drivers/i2c/busses/i2c-amd756.c
@@ -283,7 +283,7 @@ static const struct i2c_algorithm smbus_
 	.functionality	= amd756_func,
 };
 
-struct i2c_adapter amd756_smbus = {
+static struct i2c_adapter amd756_smbus = {
 	.owner		= THIS_MODULE,
 	.class          = I2C_CLASS_HWMON | I2C_CLASS_SPD,
 	.algo		= &smbus_algorithm,
@@ -398,5 +398,3 @@ module_pci_driver(amd756_driver);
 MODULE_AUTHOR("Merlin Hughes <merlin@merlin.org>");
 MODULE_DESCRIPTION("AMD756/766/768/8111 and nVidia nForce SMBus driver");
 MODULE_LICENSE("GPL");
-
-EXPORT_SYMBOL(amd756_smbus);
--- linux-6.6-rc3.orig/drivers/i2c/busses/i2c-nforce2-s4985.c
+++ /dev/null
@@ -1,240 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard
- *
- * Copyright (C) 2008 Jean Delvare <jdelvare@suse.de>
- */
-
-/*
- * We select the channels by sending commands to the Philips
- * PCA9556 chip at I2C address 0x18. The main adapter is used for
- * the non-multiplexed part of the bus, and 4 virtual adapters
- * are defined for the multiplexed addresses: 0x50-0x53 (memory
- * module EEPROM) located on channels 1-4. We define one virtual
- * adapter per CPU, which corresponds to one multiplexed channel:
- *   CPU0: virtual adapter 1, channel 1
- *   CPU1: virtual adapter 2, channel 2
- *   CPU2: virtual adapter 3, channel 3
- *   CPU3: virtual adapter 4, channel 4
- */
-
-#include <linux/module.h>
-#include <linux/kernel.h>
-#include <linux/slab.h>
-#include <linux/init.h>
-#include <linux/i2c.h>
-#include <linux/mutex.h>
-
-extern struct i2c_adapter *nforce2_smbus;
-
-static struct i2c_adapter *s4985_adapter;
-static struct i2c_algorithm *s4985_algo;
-
-/* Wrapper access functions for multiplexed SMBus */
-static DEFINE_MUTEX(nforce2_lock);
-
-static s32 nforce2_access_virt0(struct i2c_adapter *adap, u16 addr,
-				unsigned short flags, char read_write,
-				u8 command, int size,
-				union i2c_smbus_data *data)
-{
-	int error;
-
-	/* We exclude the multiplexed addresses */
-	if ((addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
-	 || addr == 0x18)
-		return -ENXIO;
-
-	mutex_lock(&nforce2_lock);
-	error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write,
-						command, size, data);
-	mutex_unlock(&nforce2_lock);
-
-	return error;
-}
-
-/* We remember the last used channels combination so as to only switch
-   channels when it is really needed. This greatly reduces the SMBus
-   overhead, but also assumes that nobody will be writing to the PCA9556
-   in our back. */
-static u8 last_channels;
-
-static inline s32 nforce2_access_channel(struct i2c_adapter *adap, u16 addr,
-					 unsigned short flags, char read_write,
-					 u8 command, int size,
-					 union i2c_smbus_data *data,
-					 u8 channels)
-{
-	int error;
-
-	/* We exclude the non-multiplexed addresses */
-	if ((addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
-		return -ENXIO;
-
-	mutex_lock(&nforce2_lock);
-	if (last_channels != channels) {
-		union i2c_smbus_data mplxdata;
-		mplxdata.byte = channels;
-
-		error = nforce2_smbus->algo->smbus_xfer(adap, 0x18, 0,
-							I2C_SMBUS_WRITE, 0x01,
-							I2C_SMBUS_BYTE_DATA,
-							&mplxdata);
-		if (error)
-			goto UNLOCK;
-		last_channels = channels;
-	}
-	error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write,
-						command, size, data);
-
-UNLOCK:
-	mutex_unlock(&nforce2_lock);
-	return error;
-}
-
-static s32 nforce2_access_virt1(struct i2c_adapter *adap, u16 addr,
-				unsigned short flags, char read_write,
-				u8 command, int size,
-				union i2c_smbus_data *data)
-{
-	/* CPU0: channel 1 enabled */
-	return nforce2_access_channel(adap, addr, flags, read_write, command,
-				      size, data, 0x02);
-}
-
-static s32 nforce2_access_virt2(struct i2c_adapter *adap, u16 addr,
-				unsigned short flags, char read_write,
-				u8 command, int size,
-				union i2c_smbus_data *data)
-{
-	/* CPU1: channel 2 enabled */
-	return nforce2_access_channel(adap, addr, flags, read_write, command,
-				      size, data, 0x04);
-}
-
-static s32 nforce2_access_virt3(struct i2c_adapter *adap, u16 addr,
-				unsigned short flags, char read_write,
-				u8 command, int size,
-				union i2c_smbus_data *data)
-{
-	/* CPU2: channel 3 enabled */
-	return nforce2_access_channel(adap, addr, flags, read_write, command,
-				      size, data, 0x08);
-}
-
-static s32 nforce2_access_virt4(struct i2c_adapter *adap, u16 addr,
-				unsigned short flags, char read_write,
-				u8 command, int size,
-				union i2c_smbus_data *data)
-{
-	/* CPU3: channel 4 enabled */
-	return nforce2_access_channel(adap, addr, flags, read_write, command,
-				      size, data, 0x10);
-}
-
-static int __init nforce2_s4985_init(void)
-{
-	int i, error;
-	union i2c_smbus_data ioconfig;
-
-	if (!nforce2_smbus)
-		return -ENODEV;
-
-	/* Configure the PCA9556 multiplexer */
-	ioconfig.byte = 0x00; /* All I/O to output mode */
-	error = i2c_smbus_xfer(nforce2_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
-			       I2C_SMBUS_BYTE_DATA, &ioconfig);
-	if (error) {
-		dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n");
-		error = -EIO;
-		goto ERROR0;
-	}
-
-	/* Unregister physical bus */
-	i2c_del_adapter(nforce2_smbus);
-
-	printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4985\n");
-	/* Define the 5 virtual adapters and algorithms structures */
-	s4985_adapter = kcalloc(5, sizeof(struct i2c_adapter), GFP_KERNEL);
-	if (!s4985_adapter) {
-		error = -ENOMEM;
-		goto ERROR1;
-	}
-	s4985_algo = kcalloc(5, sizeof(struct i2c_algorithm), GFP_KERNEL);
-	if (!s4985_algo) {
-		error = -ENOMEM;
-		goto ERROR2;
-	}
-
-	/* Fill in the new structures */
-	s4985_algo[0] = *(nforce2_smbus->algo);
-	s4985_algo[0].smbus_xfer = nforce2_access_virt0;
-	s4985_adapter[0] = *nforce2_smbus;
-	s4985_adapter[0].algo = s4985_algo;
-	s4985_adapter[0].dev.parent = nforce2_smbus->dev.parent;
-	for (i = 1; i < 5; i++) {
-		s4985_algo[i] = *(nforce2_smbus->algo);
-		s4985_adapter[i] = *nforce2_smbus;
-		snprintf(s4985_adapter[i].name, sizeof(s4985_adapter[i].name),
-			 "SMBus nForce2 adapter (CPU%d)", i - 1);
-		s4985_adapter[i].algo = s4985_algo + i;
-		s4985_adapter[i].dev.parent = nforce2_smbus->dev.parent;
-	}
-	s4985_algo[1].smbus_xfer = nforce2_access_virt1;
-	s4985_algo[2].smbus_xfer = nforce2_access_virt2;
-	s4985_algo[3].smbus_xfer = nforce2_access_virt3;
-	s4985_algo[4].smbus_xfer = nforce2_access_virt4;
-
-	/* Register virtual adapters */
-	for (i = 0; i < 5; i++) {
-		error = i2c_add_adapter(s4985_adapter + i);
-		if (error) {
-			printk(KERN_ERR "i2c-nforce2-s4985: "
-			       "Virtual adapter %d registration "
-			       "failed, module not inserted\n", i);
-			for (i--; i >= 0; i--)
-				i2c_del_adapter(s4985_adapter + i);
-			goto ERROR3;
-		}
-	}
-
-	return 0;
-
-ERROR3:
-	kfree(s4985_algo);
-	s4985_algo = NULL;
-ERROR2:
-	kfree(s4985_adapter);
-	s4985_adapter = NULL;
-ERROR1:
-	/* Restore physical bus */
-	i2c_add_adapter(nforce2_smbus);
-ERROR0:
-	return error;
-}
-
-static void __exit nforce2_s4985_exit(void)
-{
-	if (s4985_adapter) {
-		int i;
-
-		for (i = 0; i < 5; i++)
-			i2c_del_adapter(s4985_adapter+i);
-		kfree(s4985_adapter);
-		s4985_adapter = NULL;
-	}
-	kfree(s4985_algo);
-	s4985_algo = NULL;
-
-	/* Restore physical bus */
-	if (i2c_add_adapter(nforce2_smbus))
-		printk(KERN_ERR "i2c-nforce2-s4985: "
-		       "Physical bus restoration failed\n");
-}
-
-MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
-MODULE_DESCRIPTION("S4985 SMBus multiplexing");
-MODULE_LICENSE("GPL");
-
-module_init(nforce2_s4985_init);
-module_exit(nforce2_s4985_exit);
--- linux-6.6-rc3.orig/drivers/i2c/busses/i2c-nforce2.c
+++ linux-6.6-rc3/drivers/i2c/busses/i2c-nforce2.c
@@ -117,20 +117,6 @@ static const struct dmi_system_id nforce
 
 static struct pci_driver nforce2_driver;
 
-/* For multiplexing support, we need a global reference to the 1st
-   SMBus channel */
-#if IS_ENABLED(CONFIG_I2C_NFORCE2_S4985)
-struct i2c_adapter *nforce2_smbus;
-EXPORT_SYMBOL_GPL(nforce2_smbus);
-
-static void nforce2_set_reference(struct i2c_adapter *adap)
-{
-	nforce2_smbus = adap;
-}
-#else
-static inline void nforce2_set_reference(struct i2c_adapter *adap) { }
-#endif
-
 static void nforce2_abort(struct i2c_adapter *adap)
 {
 	struct nforce2_smbus *smbus = adap->algo_data;
@@ -411,7 +397,6 @@ static int nforce2_probe(struct pci_dev
 		return -ENODEV;
 	}
 
-	nforce2_set_reference(&smbuses[0].adapter);
 	return 0;
 }
 
@@ -420,7 +405,6 @@ static void nforce2_remove(struct pci_de
 {
 	struct nforce2_smbus *smbuses = pci_get_drvdata(dev);
 
-	nforce2_set_reference(NULL);
 	if (smbuses[0].base) {
 		i2c_del_adapter(&smbuses[0].adapter);
 		release_region(smbuses[0].base, smbuses[0].size);


-- 
Jean Delvare
SUSE L3 Support

Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Andi Shyti]

Hi Jean,

On Thu, Sep 28, 2023 at 10:16:55AM +0200, Jean Delvare wrote:
> The i2c-amd756-s4882 and i2c-nforce2-s4985 muxing pseudo-drivers were
> written at a time when the i2c core did not support muxing. They are
> essentially board-specific hacks. If we had to add support for these
> boards today, we would implement it in a completely different way.
> 
> These Tyan server boards are 18 years old by now, so I very much doubt
> any of these is still running today. So let's just drop this clumsy
> code. If anyone really still needs this support and complains, I'll
> rewrite it in a proper way on top of i2c-mux.
> 
> This also fixes the following warnings:
> drivers/i2c/busses/i2c-amd756.c:286:20: warning: symbol 'amd756_smbus' was not declared. Should it be static?
> drivers/i2c/busses/i2c-nforce2.c:123:20: warning: symbol 'nforce2_smbus' was not declared. Should it be static?
> 
> Signed-off-by: Jean Delvare <jdelvare@suse.de>
> Acked-by: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Andi Shyti <andi.shyti@kernel.org>

I think I commented here that I had double thoughts on this. I
said that on one hand I like the cleanup, but on the other what's
wrong keeping them here?

Maybe someone is still using these devices.

BTW, do you really have them?

Andi

Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Wolfram Sang]

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> I think I commented here that I had double thoughts on this. I

Didn't you get Jean's and my reply?


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Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Nick Desaulniers]

On Thu, Sep 28, 2023 at 8:03 AM Andi Shyti <andi.shyti@kernel.org> wrote:
>
> Hi Jean,
>
> On Thu, Sep 28, 2023 at 10:16:55AM +0200, Jean Delvare wrote:
> > The i2c-amd756-s4882 and i2c-nforce2-s4985 muxing pseudo-drivers were
> > written at a time when the i2c core did not support muxing. They are
> > essentially board-specific hacks. If we had to add support for these
> > boards today, we would implement it in a completely different way.
> >
> > These Tyan server boards are 18 years old by now, so I very much doubt
> > any of these is still running today. So let's just drop this clumsy
> > code. If anyone really still needs this support and complains, I'll
> > rewrite it in a proper way on top of i2c-mux.
> >
> > This also fixes the following warnings:
> > drivers/i2c/busses/i2c-amd756.c:286:20: warning: symbol 'amd756_smbus' was not declared. Should it be static?
> > drivers/i2c/busses/i2c-nforce2.c:123:20: warning: symbol 'nforce2_smbus' was not declared. Should it be static?
> >
> > Signed-off-by: Jean Delvare <jdelvare@suse.de>
> > Acked-by: Nick Desaulniers <ndesaulniers@google.com>
> > Cc: Andi Shyti <andi.shyti@kernel.org>
>
> I think I commented here that I had double thoughts on this. I

Please consider using an explicit NACK if you feel strongly.  My
reading of your comment was that you did not feel strongly.

> said that on one hand I like the cleanup, but on the other what's
> wrong keeping them here?

We can always resurrect the driver if someone complains, which I
believe there's prior art for.  Nothing is ever truly dead with git.
"That is not dead which can eternal lie, and with strange aeons even
death may die" or something.

>
> Maybe someone is still using these devices.
>
> BTW, do you really have them?

I think Wolfram wrote the drivers.  If he's the sole author and stuck
with maintaining these, I can totally see a maintainer saying "it's
time to put this old dog down."
-- 
Thanks,
~Nick Desaulniers

Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Wolfram Sang]

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On Thu, Sep 28, 2023 at 05:09:37PM +0200, Wolfram Sang wrote:
> 
> > I think I commented here that I had double thoughts on this. I
> 
> Didn't you get Jean's and my reply?

I have been notified that this message could be seen as impolite. It was
*totally* not meant this way. I was really wondering if the mails didn't
get through. Such things happen, so I wanted to rule them out. It maybe
was too brief. I really appreciate Andi's effort in the I2C subsystem
and have zero bad feelings or whatsoever. So, if it sounded otherwise, I
am sorry. I try to add a few more words in the future.



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Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Wolfram Sang]

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> We can always resurrect the driver if someone complains, which I

Or write a new and better one as Jean offered.

> I think Wolfram wrote the drivers.  If he's the sole author and stuck
> with maintaining these, I can totally see a maintainer saying "it's
> time to put this old dog down."

It is Jean who wrote the drivers. But your reasoning still holds true
for me.


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Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Nick Desaulniers]

On Thu, Sep 28, 2023 at 9:49 AM Wolfram Sang <wsa@kernel.org> wrote:
>
> > I think Wolfram wrote the drivers.  If he's the sole author and stuck
> > with maintaining these, I can totally see a maintainer saying "it's
> > time to put this old dog down."
>
> It is Jean who wrote the drivers. But your reasoning still holds true
> for me.

Oops! Yes sorry for mixing you two up; I should have commented back
when I checked the git log and noticed that so it would have been
fresh in my mind (or just run git log again now).

-- 
Thanks,
~Nick Desaulniers

Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Andi Shyti]

Hi Wolfram,

On Thu, Sep 28, 2023 at 06:47:28PM +0200, Wolfram Sang wrote:
> On Thu, Sep 28, 2023 at 05:09:37PM +0200, Wolfram Sang wrote:
> > 
> > > I think I commented here that I had double thoughts on this. I
> > 
> > Didn't you get Jean's and my reply?
> 
> I have been notified that this message could be seen as impolite. It was
> *totally* not meant this way. I was really wondering if the mails didn't
> get through. Such things happen, so I wanted to rule them out. It maybe
> was too brief. I really appreciate Andi's effort in the I2C subsystem
> and have zero bad feelings or whatsoever. So, if it sounded otherwise, I
> am sorry. I try to add a few more words in the future.

Thanks for the clarification and thanks for the kind words.

I didn't actually read it as unpolite.

I haven't received your replies and Jean's either, indeed I was
surprised to see this patch again. Maybe my notmuch filters need
to be a bit refined.

Anyway I will go hunt for them :)

Thanks again,
Andi

Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Nick Desaulniers]

On Thu, Sep 28, 2023 at 1:26 PM Andi Shyti <andi.shyti@kernel.org> wrote:
>
> Hi Wolfram,
>
> I haven't received your replies and Jean's either, indeed I was
> surprised to see this patch again. Maybe my notmuch filters need
> to be a bit refined.

https://lore.kernel.org/linux-i2c/20230926133725.5c3fb96e@endymion.delvare/
for the lore thread, FWIW.  I too fight with my inbox filters.
-- 
Thanks,
~Nick Desaulniers

Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Andi Shyti]

Hi Nick,

> > > The i2c-amd756-s4882 and i2c-nforce2-s4985 muxing pseudo-drivers were
> > > written at a time when the i2c core did not support muxing. They are
> > > essentially board-specific hacks. If we had to add support for these
> > > boards today, we would implement it in a completely different way.
> > >
> > > These Tyan server boards are 18 years old by now, so I very much doubt
> > > any of these is still running today. So let's just drop this clumsy
> > > code. If anyone really still needs this support and complains, I'll
> > > rewrite it in a proper way on top of i2c-mux.
> > >
> > > This also fixes the following warnings:
> > > drivers/i2c/busses/i2c-amd756.c:286:20: warning: symbol 'amd756_smbus' was not declared. Should it be static?
> > > drivers/i2c/busses/i2c-nforce2.c:123:20: warning: symbol 'nforce2_smbus' was not declared. Should it be static?
> > >
> > > Signed-off-by: Jean Delvare <jdelvare@suse.de>
> > > Acked-by: Nick Desaulniers <ndesaulniers@google.com>
> > > Cc: Andi Shyti <andi.shyti@kernel.org>
> >
> > I think I commented here that I had double thoughts on this. I
> 
> Please consider using an explicit NACK if you feel strongly.  My
> reading of your comment was that you did not feel strongly.

I'm not strong...

> > said that on one hand I like the cleanup, but on the other what's
> > wrong keeping them here?
> 
> We can always resurrect the driver if someone complains, which I
> believe there's prior art for.  Nothing is ever truly dead with git.
> "That is not dead which can eternal lie, and with strange aeons even
> death may die" or something.
> 
> >
> > Maybe someone is still using these devices.
> >
> > BTW, do you really have them?
> 
> I think Wolfram wrote the drivers.  If he's the sole author and stuck
> with maintaining these, I can totally see a maintainer saying "it's
> time to put this old dog down."

... for this reason. The maintainer/author of the driver might
feel this being a bit of a heavy burden to carry around.

I personally prefer the drivers to stay, but I'm not going to
nack this patch and I'm not going to ack it either. In any case
I'm not blocking it.

Thanks,
Andi

Re: [PATCH v2] i2c: Drop legacy muxing pseudo-drivers

[Wolfram Sang]

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On Thu, Sep 28, 2023 at 10:16:55AM +0200, Jean Delvare wrote:
> The i2c-amd756-s4882 and i2c-nforce2-s4985 muxing pseudo-drivers were
> written at a time when the i2c core did not support muxing. They are
> essentially board-specific hacks. If we had to add support for these
> boards today, we would implement it in a completely different way.
> 
> These Tyan server boards are 18 years old by now, so I very much doubt
> any of these is still running today. So let's just drop this clumsy
> code. If anyone really still needs this support and complains, I'll
> rewrite it in a proper way on top of i2c-mux.
> 
> This also fixes the following warnings:
> drivers/i2c/busses/i2c-amd756.c:286:20: warning: symbol 'amd756_smbus' was not declared. Should it be static?
> drivers/i2c/busses/i2c-nforce2.c:123:20: warning: symbol 'nforce2_smbus' was not declared. Should it be static?
> 
> Signed-off-by: Jean Delvare <jdelvare@suse.de>
> Acked-by: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Andi Shyti <andi.shyti@kernel.org>

Applied to for-next, thanks!


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