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Commit 279e9024 authored by Jean Delvare's avatar Jean Delvare Committed by Jean Delvare
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i2c-nforce2: Add support for multiplexing on the Tyan S4985 



Just like the Tyan S4882, the S4985 uses a multiplexer to give access
to all 16 memory module SPD EEPROMs. This specific i2c-nforce2-s4985
driver adds support for this. It is heavily based on the older
i2c-amd756-s4882 driver.

As more mainboards will use multiplexer chips, we will have to find a
way to support them without having to write a new specfic driver for
each. The recent changes to the i2c subsystem should help us, and the
new gpio subsystem might help, too.

Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 2e743787

drivers/i2c/busses/Kconfig

+13 −0
Original line number Diff line number Diff line
@@ -315,6 +315,19 @@ 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 && EXPERIMENTAL

	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_OCORES

	tristate "OpenCores I2C Controller"

	depends on EXPERIMENTAL

drivers/i2c/busses/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -24,6 +24,7 @@ obj-$(CONFIG_I2C_POWERMAC) += i2c-powermac.o 
obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o

obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o

obj-$(CONFIG_I2C_NFORCE2)	+= i2c-nforce2.o

obj-$(CONFIG_I2C_NFORCE2_S4985)	+= i2c-nforce2-s4985.o

obj-$(CONFIG_I2C_OCORES)	+= i2c-ocores.o

obj-$(CONFIG_I2C_OMAP)		+= i2c-omap.o

obj-$(CONFIG_I2C_PARPORT)	+= i2c-parport.o

drivers/i2c/busses/i2c-nforce2-s4985.c

0 → 100644
+257 −0
Original line number Diff line number Diff line 
/*

 * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard

 *

 * Copyright (C) 2008 Jean Delvare <khali@linux-fr.org>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

 */



/*

 * 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;



	/* Unregister physical bus */

	if (!nforce2_smbus)

		return -ENODEV;

	error = i2c_del_adapter(nforce2_smbus);

	if (error) {

		dev_err(&nforce2_smbus->dev, "Physical bus removal failed\n");

		goto ERROR0;

	}



	printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4985\n");

	/* Define the 5 virtual adapters and algorithms structures */

	s4985_adapter = kzalloc(5 * sizeof(struct i2c_adapter), GFP_KERNEL);

	if (!s4985_adapter) {

		error = -ENOMEM;

		goto ERROR1;

	}

	s4985_algo = kzalloc(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;



	/* Configure the PCA9556 multiplexer */

	ioconfig.byte = 0x00; /* All I/O to output mode */

	error = nforce2_smbus->algo->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 ERROR3;

	}



	/* Register virtual adapters */

	for (i = 0; i < 5; i++) {

		error = i2c_add_adapter(s4985_adapter + i);

		if (error) {

			dev_err(&nforce2_smbus->dev,

				"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))

		dev_err(&nforce2_smbus->dev, "Physical bus restoration "

			"failed\n");

}



MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");

MODULE_DESCRIPTION("S4985 SMBus multiplexing");

MODULE_LICENSE("GPL");



module_init(nforce2_s4985_init);

module_exit(nforce2_s4985_exit);

drivers/i2c/busses/i2c-nforce2.c

+16 −0
Original line number Diff line number Diff line
@@ -124,6 +124,20 @@ static struct dmi_system_id __devinitdata nforce2_dmi_blacklist2[] = { 


static struct pci_driver nforce2_driver;



/* For multiplexing support, we need a global reference to the 1st

   SMBus channel */

#if defined CONFIG_I2C_NFORCE2_S4985 || defined CONFIG_I2C_NFORCE2_S4985_MODULE

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;
@@ -398,6 +412,7 @@ static int __devinit nforce2_probe(struct pci_dev *dev, const struct pci_device_ 
		return -ENODEV;

	}



	nforce2_set_reference(&smbuses[0].adapter);

	return 0;

}
@@ -406,6 +421,7 @@ static void __devexit nforce2_remove(struct pci_dev *dev) 
{

	struct nforce2_smbus *smbuses = (void*) 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);