[PATCH v4 0/3] Support multiplexed main SMBus interface on SB800

[PATCH v4 0/3] Support multiplexed main SMBus interface on SB800

[Christian Fetzer]

This is an attempt to upstream the patches created by Thomas Brandon and
Eddi De Pieri to support the multiplexed main SMBus interface on the SB800
chipset. (https://www.mail-archive.com/linux-i2c@vger.kernel.org/msg06757.html)

I have mainly rebased the latest patch version and tested the driver on a
HP ProLiant MicroServer G7 N54L (where this patch allows to access sensor data
from a w83795adg).

The patched driver is running stable on the machine, given that ic2_piix4 is
loaded before jc42 and w83795. If jc42 is loaded before i2c_piix4 calling
sensors triggers some errors:
    ERROR: Can't get value of subfeature temp1_min_alarm: Can't read

While the kernel log shows:
    i2c i2c-1: Transaction (pre): CNT=0c, CMD=05, ADD=31, DAT0=03, DAT1=c0
    i2c i2c-1: Error: no response!
    i2c i2c-1: Transaction (post): CNT=0c, CMD=05, ADD=31, DAT0=ff, DAT1=ff
Unfortunately I don't know how to tackle this specific issue.

Please review and let me know required changes in order to get this upstream
finally.

Eddi, Thomas, it would be great if you could verify the changes on your
machines.

Regards,
Christian

v4:
- Incorporated changes requested by Andy
    - added mutex to struct i2c_piix4_adapdata
    - added flag for releasing SMBus index region to struct i2c_piix4_adapdata
        - this flag now indicates that the adapter is a sb800 main adapter
        - together with the port number it simplifies the adapter
          releasing and the first patch in v3 is no more needed
        - unfortunately patch 3 and 4 in v3 had to be combined as only
          the patch introducing multiplexing adds a separate add_adapters_sb800
          method that can be used to set the flag.
    - fixed releasing the SMBus index region in case setting up the
      adapter fails

v3:
- Incorporated changes requested by Mika and Andy
    - main adapter name set to 'main'
    - defined constant idx address
    - block comment style, joined string literals, reworked for loops
      into while loops

v2:
- Incorporated changes requested by Mika
    - remove adapter in reverse order
    - ERROR label
    - request base address index region only once

Christian Fetzer (3):
  i2c-piix4: Convert piix4_main_adapter to array
  i2c-piix4: Add support for multiplexed main adapter in SB800
  i2c-piix4: Add adapter port name support for SB800 chipset

 drivers/i2c/busses/i2c-piix4.c | 194 +++++++++++++++++++++++++++++++++++------
 1 file changed, 165 insertions(+), 29 deletions(-)

-- 
1.9.1

[PATCH v4 1/3] i2c-piix4: Convert piix4_main_adapter to array

[Christian Fetzer]

The SB800 chipset supports a multiplexed main SMBus controller with
four ports. Therefore the static variable piix4_main_adapter is
converted into a piix4_main_adapters array that can hold one
i2c_adapter for each multiplexed port.

The auxiliary adapter remains unchanged since it represents the second
(not multiplexed) SMBus controller on the SB800 chipset.

Signed-off-by: Christian Fetzer <fetzer.ch@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/i2c/busses/i2c-piix4.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 630bce6..9c32eb1 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -75,6 +75,9 @@
 #define PIIX4_WORD_DATA		0x0C
 #define PIIX4_BLOCK_DATA	0x14
 
+/* Multi-port constants */
+#define PIIX4_MAX_ADAPTERS 4
+
 /* insmod parameters */
 
 /* If force is set to anything different from 0, we forcibly enable the
@@ -561,7 +564,7 @@ static const struct pci_device_id piix4_ids[] = {
 
 MODULE_DEVICE_TABLE (pci, piix4_ids);
 
-static struct i2c_adapter *piix4_main_adapter;
+static struct i2c_adapter *piix4_main_adapters[PIIX4_MAX_ADAPTERS];
 static struct i2c_adapter *piix4_aux_adapter;
 
 static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
@@ -629,7 +632,7 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
 		return retval;
 
 	/* Try to register main SMBus adapter, give up if we can't */
-	retval = piix4_add_adapter(dev, retval, &piix4_main_adapter);
+	retval = piix4_add_adapter(dev, retval, &piix4_main_adapters[0]);
 	if (retval < 0)
 		return retval;
 
@@ -674,9 +677,13 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
 
 static void piix4_remove(struct pci_dev *dev)
 {
-	if (piix4_main_adapter) {
-		piix4_adap_remove(piix4_main_adapter);
-		piix4_main_adapter = NULL;
+	int port = PIIX4_MAX_ADAPTERS;
+
+	while (--port >= 0) {
+		if (piix4_main_adapters[port]) {
+			piix4_adap_remove(piix4_main_adapters[port]);
+			piix4_main_adapters[port] = NULL;
+		}
 	}
 
 	if (piix4_aux_adapter) {
-- 
1.9.1

[PATCH v4 2/3] i2c-piix4: Add support for multiplexed main adapter in SB800

[Christian Fetzer]

The SB800 chipset supports a multiplexed main SMBus controller with
four ports. The multiplexed ports share the same SMBus address and
register set. The port is selected by bits 2:1 of the smb_en register
(0x2C).

Only one port can be active at any point in time therefore a mutex is
needed in order to synchronize access.

Additionally, the commit avoids requesting and releasing the SMBus base
address index region on every multiplexed transfer by moving the
request_region call into piix4_probe.

Tested on HP ProLiant MicroServer G7 N54L (where this patch adds
support to access sensor data from the w83795adg).

Cc: Thomas Brandon <tbrandonau@gmail.com>
Cc: Eddi De Pieri <eddi@depieri.net>
Signed-off-by: Christian Fetzer <fetzer.ch@gmail.com>
---
 drivers/i2c/busses/i2c-piix4.c | 165 +++++++++++++++++++++++++++++++++++------
 1 file changed, 143 insertions(+), 22 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 9c32eb1..780f2b9 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -23,6 +23,9 @@
 
    Note: we assume there can only be one device, with one or more
    SMBus interfaces.
+   The device can register multiple i2c_adapters (up to PIIX4_MAX_ADAPTERS).
+   For devices supporting multiple ports the i2c_adapter should provide
+   an i2c_algorithm to access them.
 */
 
 #include <linux/module.h>
@@ -37,6 +40,7 @@
 #include <linux/dmi.h>
 #include <linux/acpi.h>
 #include <linux/io.h>
+#include <linux/mutex.h>
 
 
 /* PIIX4 SMBus address offsets */
@@ -78,6 +82,9 @@
 /* Multi-port constants */
 #define PIIX4_MAX_ADAPTERS 4
 
+/* SB800 constants */
+#define SB800_PIIX4_SMB_IDX 0xcd6
+
 /* insmod parameters */
 
 /* If force is set to anything different from 0, we forcibly enable the
@@ -127,6 +134,11 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
 
 struct i2c_piix4_adapdata {
 	unsigned short smba;
+
+	/* SB800 */
+	bool sb800_main;
+	unsigned short port;
+	struct mutex *mutex;
 };
 
 static int piix4_setup(struct pci_dev *PIIX4_dev,
@@ -232,7 +244,6 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
 			     const struct pci_device_id *id, u8 aux)
 {
 	unsigned short piix4_smba;
-	unsigned short smba_idx = 0xcd6;
 	u8 smba_en_lo, smba_en_hi, smb_en, smb_en_status;
 	u8 i2ccfg, i2ccfg_offset = 0x10;
 
@@ -254,16 +265,10 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
 	else
 		smb_en = (aux) ? 0x28 : 0x2c;
 
-	if (!request_region(smba_idx, 2, "smba_idx")) {
-		dev_err(&PIIX4_dev->dev, "SMBus base address index region "
-			"0x%x already in use!\n", smba_idx);
-		return -EBUSY;
-	}
-	outb_p(smb_en, smba_idx);
-	smba_en_lo = inb_p(smba_idx + 1);
-	outb_p(smb_en + 1, smba_idx);
-	smba_en_hi = inb_p(smba_idx + 1);
-	release_region(smba_idx, 2);
+	outb_p(smb_en, SB800_PIIX4_SMB_IDX);
+	smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
+	outb_p(smb_en + 1, SB800_PIIX4_SMB_IDX);
+	smba_en_hi = inb_p(SB800_PIIX4_SMB_IDX + 1);
 
 	if (!smb_en) {
 		smb_en_status = smba_en_lo & 0x10;
@@ -527,6 +532,43 @@ static s32 piix4_access(struct i2c_adapter * adap, u16 addr,
 	return 0;
 }
 
+/*
+ * Handles access to multiple SMBus ports on the SB800.
+ * The port is selected by bits 2:1 of the smb_en register (0x2C).
+ * Returns negative errno on error.
+ *
+ * Note: The selected port must be returned to the initial selection to avoid
+ * problems on certain systems.
+ */
+static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
+		 unsigned short flags, char read_write,
+		 u8 command, int size, union i2c_smbus_data *data)
+{
+	struct i2c_piix4_adapdata *adapdata = i2c_get_adapdata(adap);
+	u8 smba_en_lo, smb_en = 0x2c;
+	u8 port;
+	int retval;
+
+	mutex_lock(adapdata->mutex);
+
+	outb_p(smb_en, SB800_PIIX4_SMB_IDX);
+	smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
+
+	port = adapdata->port;
+	if ((smba_en_lo & 6) != (port << 1))
+		outb_p((smba_en_lo & ~6) | (port << 1),
+		       SB800_PIIX4_SMB_IDX + 1);
+
+	retval = piix4_access(adap, addr, flags, read_write,
+			      command, size, data);
+
+	outb_p(smba_en_lo, SB800_PIIX4_SMB_IDX + 1);
+
+	mutex_unlock(adapdata->mutex);
+
+	return retval;
+}
+
 static u32 piix4_func(struct i2c_adapter *adapter)
 {
 	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
@@ -539,6 +581,11 @@ static const struct i2c_algorithm smbus_algorithm = {
 	.functionality	= piix4_func,
 };
 
+static const struct i2c_algorithm piix4_smbus_algorithm_sb800 = {
+	.smbus_xfer	= piix4_access_sb800,
+	.functionality	= piix4_func,
+};
+
 static const struct pci_device_id piix4_ids[] = {
 	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82371AB_3) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL, PCI_DEVICE_ID_INTEL_82443MX_3) },
@@ -614,6 +661,53 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
 	return 0;
 }
 
+static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba)
+{
+	struct mutex *mutex;
+	struct i2c_piix4_adapdata *adapdata;
+	int port;
+	int retval;
+
+	mutex = kzalloc(sizeof(*mutex), GFP_KERNEL);
+	if (mutex == NULL)
+		return -ENOMEM;
+
+	mutex_init(mutex);
+
+	for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
+		retval = piix4_add_adapter(dev, smba,
+					   &piix4_main_adapters[port]);
+		if (retval < 0)
+			goto error;
+
+		piix4_main_adapters[port]->algo = &piix4_smbus_algorithm_sb800;
+
+		adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
+		adapdata->sb800_main = true;
+		adapdata->port = port;
+		adapdata->mutex = mutex;
+	}
+
+	return retval;
+
+error:
+	dev_err(&dev->dev,
+		"Error setting up SB800 adapters. Unregistering!\n");
+	while (--port >= 0) {
+		adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
+		if (adapdata->smba) {
+			i2c_del_adapter(piix4_main_adapters[port]);
+			kfree(adapdata);
+			kfree(piix4_main_adapters[port]);
+			piix4_main_adapters[port] = NULL;
+		}
+	}
+
+	kfree(mutex);
+
+	return retval;
+}
+
 static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
 {
 	int retval;
@@ -621,20 +715,41 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if ((dev->vendor == PCI_VENDOR_ID_ATI &&
 	     dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
 	     dev->revision >= 0x40) ||
-	    dev->vendor == PCI_VENDOR_ID_AMD)
+	    dev->vendor == PCI_VENDOR_ID_AMD) {
+		if (!request_region(SB800_PIIX4_SMB_IDX, 2, "smba_idx")) {
+			dev_err(&dev->dev,
+			"SMBus base address index region 0x%x already in use!\n",
+			SB800_PIIX4_SMB_IDX);
+			return -EBUSY;
+		}
+
 		/* base address location etc changed in SB800 */
 		retval = piix4_setup_sb800(dev, id, 0);
-	else
-		retval = piix4_setup(dev, id);
+		if (retval < 0) {
+			release_region(SB800_PIIX4_SMB_IDX, 2);
+			return retval;
+		}
 
-	/* If no main SMBus found, give up */
-	if (retval < 0)
-		return retval;
+		/*
+		 * Try to register multiplexed main SMBus adapter,
+		 * give up if we can't
+		 */
+		retval = piix4_add_adapters_sb800(dev, retval);
+		if (retval < 0) {
+			release_region(SB800_PIIX4_SMB_IDX, 2);
+			return retval;
+		}
+	} else {
+		retval = piix4_setup(dev, id);
+		if (retval < 0)
+			return retval;
 
-	/* Try to register main SMBus adapter, give up if we can't */
-	retval = piix4_add_adapter(dev, retval, &piix4_main_adapters[0]);
-	if (retval < 0)
-		return retval;
+		/* Try to register main SMBus adapter, give up if we can't */
+		retval = piix4_add_adapter(dev, retval,
+					   &piix4_main_adapters[0]);
+		if (retval < 0)
+			return retval;
+	}
 
 	/* Check for auxiliary SMBus on some AMD chipsets */
 	retval = -ENODEV;
@@ -669,7 +784,13 @@ static void piix4_adap_remove(struct i2c_adapter *adap)
 
 	if (adapdata->smba) {
 		i2c_del_adapter(adap);
-		release_region(adapdata->smba, SMBIOSIZE);
+		if (adapdata->port == 0) {
+			release_region(adapdata->smba, SMBIOSIZE);
+			if (adapdata->sb800_main) {
+				kfree(adapdata->mutex);
+				release_region(SB800_PIIX4_SMB_IDX, 2);
+			}
+		}
 		kfree(adapdata);
 		kfree(adap);
 	}
-- 
1.9.1

[PATCH v4 3/3] i2c-piix4: Add adapter port name support for SB800 chipset

[Christian Fetzer]

This patch adds support for port names for the SB800 chipset.
Since the chipset supports a multiplexed main SMBus controller, adding
the channel name to the adapter name is necessary to differentiate the
ports better (for example in sensors output).

Signed-off-by: Christian Fetzer <fetzer.ch@gmail.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/i2c/busses/i2c-piix4.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
index 780f2b9..cd2b098 100644
--- a/drivers/i2c/busses/i2c-piix4.c
+++ b/drivers/i2c/busses/i2c-piix4.c
@@ -132,6 +132,12 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
 	{ },
 };
 
+/* SB800 globals */
+static const char *piix4_main_port_names_sb800[PIIX4_MAX_ADAPTERS] = {
+	"SDA0", "SDA2", "SDA3", "SDA4"
+};
+static const char *piix4_aux_port_name_sb800 = "SDA1";
+
 struct i2c_piix4_adapdata {
 	unsigned short smba;
 
@@ -615,7 +621,7 @@ static struct i2c_adapter *piix4_main_adapters[PIIX4_MAX_ADAPTERS];
 static struct i2c_adapter *piix4_aux_adapter;
 
 static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
-			     struct i2c_adapter **padap)
+			     const char *name, struct i2c_adapter **padap)
 {
 	struct i2c_adapter *adap;
 	struct i2c_piix4_adapdata *adapdata;
@@ -644,7 +650,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
 	adap->dev.parent = &dev->dev;
 
 	snprintf(adap->name, sizeof(adap->name),
-		"SMBus PIIX4 adapter at %04x", smba);
+		"SMBus PIIX4 adapter %s at %04x", name, smba);
 
 	i2c_set_adapdata(adap, adapdata);
 
@@ -676,6 +682,7 @@ static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned short smba)
 
 	for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
 		retval = piix4_add_adapter(dev, smba,
+					   piix4_main_port_names_sb800[port],
 					   &piix4_main_adapters[port]);
 		if (retval < 0)
 			goto error;
@@ -745,7 +752,7 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
 			return retval;
 
 		/* Try to register main SMBus adapter, give up if we can't */
-		retval = piix4_add_adapter(dev, retval,
+		retval = piix4_add_adapter(dev, retval, "main",
 					   &piix4_main_adapters[0]);
 		if (retval < 0)
 			return retval;
@@ -772,7 +779,8 @@ static int piix4_probe(struct pci_dev *dev, const struct pci_device_id *id)
 	if (retval > 0) {
 		/* Try to add the aux adapter if it exists,
 		 * piix4_add_adapter will clean up if this fails */
-		piix4_add_adapter(dev, retval, &piix4_aux_adapter);
+		piix4_add_adapter(dev, retval, piix4_aux_port_name_sb800,
+				  &piix4_aux_adapter);
 	}
 
 	return 0;
-- 
1.9.1

Re: [PATCH v4 0/3] Support multiplexed main SMBus interface on SB800

[Andy Shevchenko]

On Sun, 2015-11-15 at 12:33 +0100, Christian Fetzer wrote:
> This is an attempt to upstream the patches created by Thomas Brandon
> and
> Eddi De Pieri to support the multiplexed main SMBus interface on the
> SB800
> chipset. (https://www.mail-archive.com/linux-i2c@vger.kernel.org/msg0
> 6757.html)
> 
> I have mainly rebased the latest patch version and tested the driver
> on a
> HP ProLiant MicroServer G7 N54L (where this patch allows to access
> sensor data
> from a w83795adg).
> 
> The patched driver is running stable on the machine, given that
> ic2_piix4 is
> loaded before jc42 and w83795. If jc42 is loaded before i2c_piix4
> calling
> sensors triggers some errors:
>     ERROR: Can't get value of subfeature temp1_min_alarm: Can't read
> 
> While the kernel log shows:
>     i2c i2c-1: Transaction (pre): CNT=0c, CMD=05, ADD=31, DAT0=03,
> DAT1=c0
>     i2c i2c-1: Error: no response!
>     i2c i2c-1: Transaction (post): CNT=0c, CMD=05, ADD=31, DAT0=ff,
> DAT1=ff
> Unfortunately I don't know how to tackle this specific issue.
> 
> Please review and let me know required changes in order to get this
> upstream
> finally.

One nitpick in one patch, though it looks okay for me:

Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> 
> Eddi, Thomas, it would be great if you could verify the changes on
> your
> machines.
> 
> Regards,
> Christian
> 
> v4:
> - Incorporated changes requested by Andy
>     - added mutex to struct i2c_piix4_adapdata
>     - added flag for releasing SMBus index region to struct
> i2c_piix4_adapdata
>         - this flag now indicates that the adapter is a sb800 main
> adapter
>         - together with the port number it simplifies the adapter
>           releasing and the first patch in v3 is no more needed
>         - unfortunately patch 3 and 4 in v3 had to be combined as
> only
>           the patch introducing multiplexing adds a separate
> add_adapters_sb800
>           method that can be used to set the flag.
>     - fixed releasing the SMBus index region in case setting up the
>       adapter fails
> 
> v3:
> - Incorporated changes requested by Mika and Andy
>     - main adapter name set to 'main'
>     - defined constant idx address
>     - block comment style, joined string literals, reworked for loops
>       into while loops
> 
> v2:
> - Incorporated changes requested by Mika
>     - remove adapter in reverse order
>     - ERROR label
>     - request base address index region only once
> 
> Christian Fetzer (3):
>   i2c-piix4: Convert piix4_main_adapter to array
>   i2c-piix4: Add support for multiplexed main adapter in SB800
>   i2c-piix4: Add adapter port name support for SB800 chipset
> 
>  drivers/i2c/busses/i2c-piix4.c | 194
> +++++++++++++++++++++++++++++++++++------
>  1 file changed, 165 insertions(+), 29 deletions(-)
> 

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v4 2/3] i2c-piix4: Add support for multiplexed main adapter in SB800

[Andy Shevchenko]

On Sun, 2015-11-15 at 12:33 +0100, Christian Fetzer wrote:
> The SB800 chipset supports a multiplexed main SMBus controller with
> four ports. The multiplexed ports share the same SMBus address and
> register set. The port is selected by bits 2:1 of the smb_en register
> (0x2C).
> 
> Only one port can be active at any point in time therefore a mutex is
> needed in order to synchronize access.
> 
> Additionally, the commit avoids requesting and releasing the SMBus
> base
> address index region on every multiplexed transfer by moving the
> request_region call into piix4_probe.
> 
> Tested on HP ProLiant MicroServer G7 N54L (where this patch adds
> support to access sensor data from the w83795adg).

One nitpick below.

> 
> +/*
> + * Handles access to multiple SMBus ports on the SB800.
> 

> + * The port is selected by bits 2:1 of the smb_en register (0x2C).

(1)

> + * Returns negative errno on error.
> + *
> + * Note: The selected port must be returned to the initial selection
> to avoid
> + * problems on certain systems.
> + */
> +static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
> +		 unsigned short flags, char read_write,
> +		 u8 command, int size, union i2c_smbus_data *data)
> +{
> +	struct i2c_piix4_adapdata *adapdata =
> i2c_get_adapdata(adap);
> +	u8 smba_en_lo, smb_en = 0x2c;
> +	u8 port;
> +	int retval;
> +
> +	mutex_lock(adapdata->mutex);
> +
> +	outb_p(smb_en, SB800_PIIX4_SMB_IDX);
> +	smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
> +
> +	port = adapdata->port;
> +	if ((smba_en_lo & 6) != (port << 1))

I think it would be nice to have a definition for magic number along
with (1).

/* The port is selected by bits 2:1 of the smb_en register (0x2C) */
#define SB800_PIIX4_PORT_IDX_MASK 0x06

> +		outb_p((smba_en_lo & ~6) | (port << 1),
> +		       SB800_PIIX4_SMB_IDX + 1);
> +
> +	retval = piix4_access(adap, addr, flags, read_write,
> +			      command, size, data);
> +
> +	outb_p(smba_en_lo, SB800_PIIX4_SMB_IDX + 1);
> +
> +	mutex_unlock(adapdata->mutex);
> +
> +	return retval;
> +}
> +
>  static u32 piix4_func(struct i2c_adapter *adapter)
>  {
>  	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
> @@ -539,6 +581,11 @@ static const struct i2c_algorithm
> smbus_algorithm = {
>  	.functionality	= piix4_func,
>  };
>  
> +static const struct i2c_algorithm piix4_smbus_algorithm_sb800 = {
> +	.smbus_xfer	= piix4_access_sb800,
> +	.functionality	= piix4_func,
> +};
> +
>  static const struct pci_device_id piix4_ids[] = {
>  	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL,
> PCI_DEVICE_ID_INTEL_82371AB_3) },
>  	{ PCI_DEVICE(PCI_VENDOR_ID_INTEL,
> PCI_DEVICE_ID_INTEL_82443MX_3) },
> @@ -614,6 +661,53 @@ static int piix4_add_adapter(struct pci_dev
> *dev, unsigned short smba,
>  	return 0;
>  }
>  
> +static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned
> short smba)
> +{
> +	struct mutex *mutex;
> +	struct i2c_piix4_adapdata *adapdata;
> +	int port;
> +	int retval;
> +
> +	mutex = kzalloc(sizeof(*mutex), GFP_KERNEL);
> +	if (mutex == NULL)
> +		return -ENOMEM;
> +
> +	mutex_init(mutex);
> +
> +	for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
> +		retval = piix4_add_adapter(dev, smba,
> +					   &piix4_main_adapters[port
> ]);
> +		if (retval < 0)
> +			goto error;
> +
> +		piix4_main_adapters[port]->algo =
> &piix4_smbus_algorithm_sb800;
> +
> +		adapdata =
> i2c_get_adapdata(piix4_main_adapters[port]);
> +		adapdata->sb800_main = true;
> +		adapdata->port = port;
> +		adapdata->mutex = mutex;
> +	}
> +
> +	return retval;
> +
> +error:
> +	dev_err(&dev->dev,
> +		"Error setting up SB800 adapters.
> Unregistering!\n");
> +	while (--port >= 0) {
> +		adapdata =
> i2c_get_adapdata(piix4_main_adapters[port]);
> +		if (adapdata->smba) {
> +			i2c_del_adapter(piix4_main_adapters[port]);
> +			kfree(adapdata);
> +			kfree(piix4_main_adapters[port]);
> +			piix4_main_adapters[port] = NULL;
> +		}
> +	}
> +
> +	kfree(mutex);
> +
> +	return retval;
> +}
> +
>  static int piix4_probe(struct pci_dev *dev, const struct
> pci_device_id *id)
>  {
>  	int retval;
> @@ -621,20 +715,41 @@ static int piix4_probe(struct pci_dev *dev,
> const struct pci_device_id *id)
>  	if ((dev->vendor == PCI_VENDOR_ID_ATI &&
>  	     dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
>  	     dev->revision >= 0x40) ||
> -	    dev->vendor == PCI_VENDOR_ID_AMD)
> +	    dev->vendor == PCI_VENDOR_ID_AMD) {
> +		if (!request_region(SB800_PIIX4_SMB_IDX, 2,
> "smba_idx")) {
> +			dev_err(&dev->dev,
> +			"SMBus base address index region 0x%x
> already in use!\n",
> +			SB800_PIIX4_SMB_IDX);
> +			return -EBUSY;
> +		}
> +
>  		/* base address location etc changed in SB800 */
>  		retval = piix4_setup_sb800(dev, id, 0);
> -	else
> -		retval = piix4_setup(dev, id);
> +		if (retval < 0) {
> +			release_region(SB800_PIIX4_SMB_IDX, 2);
> +			return retval;
> +		}
>  
> -	/* If no main SMBus found, give up */
> -	if (retval < 0)
> -		return retval;
> +		/*
> +		 * Try to register multiplexed main SMBus adapter,
> +		 * give up if we can't
> +		 */
> +		retval = piix4_add_adapters_sb800(dev, retval);
> +		if (retval < 0) {
> +			release_region(SB800_PIIX4_SMB_IDX, 2);
> +			return retval;
> +		}
> +	} else {
> +		retval = piix4_setup(dev, id);
> +		if (retval < 0)
> +			return retval;
>  
> -	/* Try to register main SMBus adapter, give up if we can't
> */
> -	retval = piix4_add_adapter(dev, retval,
> &piix4_main_adapters[0]);
> -	if (retval < 0)
> -		return retval;
> +		/* Try to register main SMBus adapter, give up if we
> can't */
> +		retval = piix4_add_adapter(dev, retval,
> +					   &piix4_main_adapters[0]);
> +		if (retval < 0)
> +			return retval;
> +	}
>  
>  	/* Check for auxiliary SMBus on some AMD chipsets */
>  	retval = -ENODEV;
> @@ -669,7 +784,13 @@ static void piix4_adap_remove(struct i2c_adapter
> *adap)
>  
>  	if (adapdata->smba) {
>  		i2c_del_adapter(adap);
> -		release_region(adapdata->smba, SMBIOSIZE);
> +		if (adapdata->port == 0) {
> +			release_region(adapdata->smba, SMBIOSIZE);
> +			if (adapdata->sb800_main) {
> +				kfree(adapdata->mutex);
> +				release_region(SB800_PIIX4_SMB_IDX,
> 2);
> +			}
> +		}
>  		kfree(adapdata);
>  		kfree(adap);
>  	}

-- 
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Intel Finland Oy

Re: [PATCH v4 2/3] i2c-piix4: Add support for multiplexed main adapter in SB800

[Mika Westerberg]

On Sun, Nov 15, 2015 at 12:33:03PM +0100, Christian Fetzer wrote:
> The SB800 chipset supports a multiplexed main SMBus controller with
> four ports. The multiplexed ports share the same SMBus address and
> register set. The port is selected by bits 2:1 of the smb_en register
> (0x2C).
> 
> Only one port can be active at any point in time therefore a mutex is
> needed in order to synchronize access.
> 
> Additionally, the commit avoids requesting and releasing the SMBus base
> address index region on every multiplexed transfer by moving the
> request_region call into piix4_probe.
> 
> Tested on HP ProLiant MicroServer G7 N54L (where this patch adds
> support to access sensor data from the w83795adg).
> 
> Cc: Thomas Brandon <tbrandonau@gmail.com>
> Cc: Eddi De Pieri <eddi@depieri.net>
> Signed-off-by: Christian Fetzer <fetzer.ch@gmail.com>

Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>