Re: [PATCH 1/3] i2c-piix4: eliminate global I/O base address

[Jean Delvare <khali@linux-fr.org>]

Hi Andrew,

On Mon,  4 Jun 2012 21:49:22 -0400, Andrew Armenia wrote:
> The i2c-piix4 driver used a global variable to store the base address
> of the piix4 i2c registers. Some chipsets contain multiple sets of
> i2c registers; thus it is desirable to eliminate global state.
> 
> i2c_get_adapdata()/i2c_set_adapdata() are used to keep track
> of the IO base address; this is passed into piix4_transaction() as
> an argument, eliminating the global variable.
> 
> Signed-off-by: Andrew Armenia <andrew@asquaredlabs.com>
> ---
>  drivers/i2c/busses/i2c-piix4.c |   61 ++++++++++++++++++++++++++++++----------
>  1 file changed, 46 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> index c14d48d..7a5889c 100644
> --- a/drivers/i2c/busses/i2c-piix4.c
> +++ b/drivers/i2c/busses/i2c-piix4.c
> @@ -94,7 +94,6 @@ MODULE_PARM_DESC(force_addr,
>  		 "Forcibly enable the PIIX4 at the given address. "
>  		 "EXTREMELY DANGEROUS!");
>  
> -static unsigned short piix4_smba;
>  static int srvrworks_csb5_delay;
>  static struct pci_driver piix4_driver;
>  static struct i2c_adapter piix4_adapter;
> @@ -127,10 +126,16 @@ static struct dmi_system_id __devinitdata piix4_dmi_ibm[] = {
>  	{ },
>  };
>  
> +struct i2c_piix4_adapdata {
> +	unsigned short smba;
> +};
> +
>  static int __devinit piix4_setup(struct pci_dev *PIIX4_dev,
> -				const struct pci_device_id *id)
> +				const struct pci_device_id *id,
> +				unsigned short *smba)

You could instead return the smba value, as the return value is
currently only used for errors. This would avoid the extra parameter
and possibly false-positive compiler warnings.

>  {
>  	unsigned char temp;
> +	unsigned short piix4_smba;
>  
>  	if ((PIIX4_dev->vendor == PCI_VENDOR_ID_SERVERWORKS) &&
>  	    (PIIX4_dev->device == PCI_DEVICE_ID_SERVERWORKS_CSB5))
> @@ -224,12 +229,15 @@ static int __devinit piix4_setup(struct pci_dev *PIIX4_dev,
>  		 "SMBus Host Controller at 0x%x, revision %d\n",
>  		 piix4_smba, temp);
>  
> +	*smba = piix4_smba;
>  	return 0;
>  }
>  
>  static int __devinit piix4_setup_sb800(struct pci_dev *PIIX4_dev,
> -				const struct pci_device_id *id)
> +				const struct pci_device_id *id,
> +				unsigned short *smba)
>  {
> +	unsigned short piix4_smba;
>  	unsigned short smba_idx = 0xcd6;
>  	u8 smba_en_lo, smba_en_hi, i2ccfg, i2ccfg_offset = 0x10, smb_en = 0x2c;
>  
> @@ -288,10 +296,11 @@ static int __devinit piix4_setup_sb800(struct pci_dev *PIIX4_dev,
>  		 "SMBus Host Controller at 0x%x, revision %d\n",
>  		 piix4_smba, i2ccfg >> 4);
>  
> +	*smba = piix4_smba;
>  	return 0;
>  }
>  
> -static int piix4_transaction(void)
> +static int piix4_transaction(unsigned short piix4_smba)
>  {
>  	int temp;
>  	int result = 0;
> @@ -372,6 +381,11 @@ static s32 piix4_access(struct i2c_adapter * adap, u16 addr,
>  {
>  	int i, len;
>  	int status;
> +	unsigned short piix4_smba;
> +	struct i2c_piix4_adapdata *adapdata;
> +
> +	adapdata = (struct i2c_piix4_adapdata *)i2c_get_adapdata(adap);

Useless cast.

> +	piix4_smba = adapdata->smba;
>  
>  	switch (size) {
>  	case I2C_SMBUS_QUICK:
> @@ -426,7 +440,7 @@ static s32 piix4_access(struct i2c_adapter * adap, u16 addr,
>  
>  	outb_p((size & 0x1C) + (ENABLE_INT9 & 1), SMBHSTCNT);
>  
> -	status = piix4_transaction();
> +	status = piix4_transaction(piix4_smba);
>  	if (status)
>  		return status;
>  
> @@ -472,6 +486,10 @@ static struct i2c_adapter piix4_adapter = {
>  	.algo		= &smbus_algorithm,
>  };
>  
> +static struct i2c_piix4_adapdata piix4_adapter_data = {
> +	.smba		= 0,
> +};

Useless initialization, 0 is the default.

> +
>  static DEFINE_PCI_DEVICE_TABLE(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) },
> @@ -500,15 +518,16 @@ static int __devinit piix4_probe(struct pci_dev *dev,
>  				const struct pci_device_id *id)
>  {
>  	int retval;
> +	unsigned short smba;
>  
>  	if ((dev->vendor == PCI_VENDOR_ID_ATI &&
>  	     dev->device == PCI_DEVICE_ID_ATI_SBX00_SMBUS &&
>  	     dev->revision >= 0x40) ||
>  	    dev->vendor == PCI_VENDOR_ID_AMD)
>  		/* base address location etc changed in SB800 */
> -		retval = piix4_setup_sb800(dev, id);
> +		retval = piix4_setup_sb800(dev, id, &smba);
>  	else
> -		retval = piix4_setup(dev, id);
> +		retval = piix4_setup(dev, id, &smba);
>  
>  	if (retval)
>  		return retval;
> @@ -517,26 +536,38 @@ static int __devinit piix4_probe(struct pci_dev *dev,
>  	piix4_adapter.dev.parent = &dev->dev;
>  
>  	snprintf(piix4_adapter.name, sizeof(piix4_adapter.name),
> -		"SMBus PIIX4 adapter at %04x", piix4_smba);
> +		"SMBus PIIX4 adapter at %04x", smba);
> +
> +	piix4_adapter_data.smba = smba;
> +
> +	i2c_set_adapdata(&piix4_adapter, &piix4_adapter_data);
>  
>  	if ((retval = i2c_add_adapter(&piix4_adapter))) {
>  		dev_err(&dev->dev, "Couldn't register adapter!\n");
> -		release_region(piix4_smba, SMBIOSIZE);
> -		piix4_smba = 0;
> +		release_region(smba, SMBIOSIZE);
> +		piix4_adapter_data.smba = 0;
>  	}
>  
>  	return retval;
>  }
>  
> -static void __devexit piix4_remove(struct pci_dev *dev)
> +static void piix4_adap_remove(struct i2c_adapter *adap)

Called from a __devinit function so it can be made __devinit too.

>  {
> -	if (piix4_smba) {
> -		i2c_del_adapter(&piix4_adapter);
> -		release_region(piix4_smba, SMBIOSIZE);
> -		piix4_smba = 0;
> +	struct i2c_piix4_adapdata *adapdata;
> +
> +	adapdata = (struct i2c_piix4_adapdata *)i2c_get_adapdata(adap);

Useless cast.

> +	if (adapdata->smba) {
> +		i2c_del_adapter(adap);
> +		release_region(adapdata->smba, SMBIOSIZE);
> +		adapdata->smba = 0;
>  	}
>  }
>  
> +static void __devexit piix4_remove(struct pci_dev *dev)
> +{
> +	piix4_adap_remove(&piix4_adapter);
> +}
> +
>  static struct pci_driver piix4_driver = {
>  	.name		= "piix4_smbus",
>  	.id_table	= piix4_ids,


-- 
Jean Delvare