Re: [PATCH v3 4/5] i2c-piix4: Add support for multiplexed main adapter in SB800

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Sat, 2015-11-07 at 12:35 +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.
> 
> 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>
> ---
>  drivers/i2c/busses/i2c-piix4.c | 105
> +++++++++++++++++++++++++++++++++++++++--
>  1 file changed, 100 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-
> piix4.c
> index 67ada1e..4beaa3d 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 */
> @@ -129,10 +133,12 @@ static const struct dmi_system_id
> piix4_dmi_ibm[] = {
>  };
>  
>  /* SB800 globals */
> +DEFINE_MUTEX(piix4_mutex_sb800);

Same question as for patch 3.

>  static bool piix4_smb_idx_sb800;
>  
>  struct i2c_piix4_adapdata {
>  	unsigned short smba;
> +	unsigned short port;
>  };
>  
>  static int piix4_setup(struct pci_dev *PIIX4_dev,
> @@ -312,6 +318,8 @@ static int piix4_setup_sb800(struct pci_dev
> *PIIX4_dev,
>  	else
>  		dev_dbg(&PIIX4_dev->dev, "Using SMI# for SMBus\n");
>  
> +	mutex_init(&piix4_mutex_sb800);
> +
>  	dev_info(&PIIX4_dev->dev,
>  		 "SMBus Host Controller at 0x%x, revision %d\n",
>  		 piix4_smba, i2ccfg >> 4);
> @@ -526,6 +534,43 @@ 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(&piix4_mutex_sb800);
> +
> +	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(&piix4_mutex_sb800);
> +
> +	return retval;
> +}
> +
>  static u32 piix4_func(struct i2c_adapter *adapter)
>  {
>  	return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
> @@ -538,6 +583,11 @@ 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) },
> @@ -613,6 +663,42 @@ 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)
> +{
> +	unsigned short port;

This one has to be at least signed and int to be aligned with patch 2.

> +	int retval;
> +	struct i2c_piix4_adapdata *adapdata;

These lines better to exchange.

> +
> +	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->port = port;
> +	}
> +
> +	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;
> +		}
> +	}
> +
> +	return retval;
> +}
> +
>  static int piix4_probe(struct pci_dev *dev, const struct
> pci_device_id *id)
>  {
>  	int retval;
> @@ -631,19 +717,28 @@ static int piix4_probe(struct pci_dev *dev,
> const struct pci_device_id *id)
>  
>  		/* base address location etc changed in SB800 */
>  		retval = piix4_setup_sb800(dev, id, 0);
> +		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);
>  	} 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 no main SMBus found, give up */
>  	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;
>  

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