Re: [PATCH v2 4/5] i2c-piix4: Add support for multiplexed main adapter in SB800

[Mika Westerberg]

On Sun, Nov 01, 2015 at 05:32:08PM +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 
> Cc: Eddi De Pieri 
> Signed-off-by: Christian Fetzer 

Few minor comments, see below.

Regardless of them,

Reviewed-by: Mika Westerberg 

> ---
>  drivers/i2c/busses/i2c-piix4.c | 102 
> +++--
>  1 file changed, 97 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index d866b58..54f8af5 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 
> @@ -37,6 +40,7 @@
>  #include 
>  #include 
>  #include 
> +#include 
>  
>  
>  /* PIIX4 SMBus address offsets */
> @@ -126,10 +130,12 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
>  };
>  
>  /* SB800 globals */
> +DEFINE_MUTEX(piix4_mutex_sb800);
>  static unsigned short piix4_smb_idx_sb800;
>  
>  struct i2c_piix4_adapdata {
>   unsigned short smba;
> + unsigned short port;
>  };
>  
>  static int piix4_setup(struct pci_dev *PIIX4_dev,
> @@ -309,6 +315,8 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
>   else
>   dev_dbg(_dev->dev, "Using SMI# for SMBus\n");
>  
> + mutex_init(_mutex_sb800);
> +
>   dev_info(_dev->dev,
>"SMBus Host Controller at 0x%x, revision %d\n",
>piix4_smba, i2ccfg >> 4);
> @@ -523,6 +531,42 @@ 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.

Block comments look like:

   /*
* Handles access to multiple...
*

> + *
> + * 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(_mutex_sb800);
> +
> + outb_p(smb_en, piix4_smb_idx_sb800);
> + smba_en_lo = inb_p(piix4_smb_idx_sb800 + 1);
> +
> + port = adapdata->port;
> + if ((smba_en_lo & 6) != (port << 1))
> + outb_p((smba_en_lo & ~6) | (port << 1),
> +piix4_smb_idx_sb800 + 1);
> +
> + retval = piix4_access(adap, addr, flags, read_write,
> +   command, size, data);
> +
> + outb_p(smba_en_lo, piix4_smb_idx_sb800 + 1);
> +
> + mutex_unlock(_mutex_sb800);
> +
> + return retval;
> +}
> +
>  static u32 piix4_func(struct i2c_adapter *adapter)
>  {
>   return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |
> @@ -535,6 +579,11 @@ 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) },
> @@ -610,6 +659,42 @@ 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;
> + int retval;
> + struct i2c_piix4_adapdata *adapdata;
> +
> + for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
> + retval = piix4_add_adapter(dev, smba,
> +_main_adapters[port]);
> + if (retval < 0)
> + goto error;
> +
> + piix4_main_adapters[port]->algo = _smbus_algorithm_sb800;
> +
> + adapdata = i2c_get_adapdata(piix4_main_adapters[port]);
> + 

Re: [PATCH v2 4/5] i2c-piix4: Add support for multiplexed main adapter in SB800

[Andy Shevchenko]

On Sun, 2015-11-01 at 17:32 +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).


> 
> +static int piix4_add_adapters_sb800(struct pci_dev *dev, unsigned
> short smba)
> +{
> + unsigned short port;
> + int retval;
> + struct i2c_piix4_adapdata *adapdata;
> +
> + for (port = 0; port < PIIX4_MAX_ADAPTERS; port++) {
> + retval = piix4_add_adapter(dev, smba,
> +    _main_adapters[port
> ]);
> + if (retval < 0)
> + goto error;
> +
> + piix4_main_adapters[port]->algo =
> _smbus_algorithm_sb800;
> +
> + adapdata =
> i2c_get_adapdata(piix4_main_adapters[port]);
> + adapdata->port = port;
> + }
> +
> + return retval;
> +
> +error:
> + dev_err(>dev, "Error setting up SB800 adapters. "
> + "Unregistering all adapters!\n");

This one Mika told already about.
You might use as well

dev_err(>dev,
 "…\n")


> + for (port--; port >= 0; port--) {

Isn't look complicated? Like I comment in one of previous patches:

while (--port) {

> + 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)
>  {
>   unsigned short smba_idx = 0xcd6;
> @@ -629,19 +714,26 @@ 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 */

Block comment
/*
 * text1
 * text2
 */

> + 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,
> +    _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,
> _main_adapters[0]);
> - if (retval < 0)
> - return retval;
> -
>   /* Check for auxiliary SMBus on some AMD chipsets */
>   retval = -ENODEV;
>  

-- 
Andy Shevchenko 
Intel Finland Oy

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