Re: [PATCH] i2c: piix4: Fix SMBus port selection for AMD Family 17h chips

[Guenter Roeck <linux@xxxxxxxxxxxx>]

On 08/12/2017 04:33 AM, Wolfram Sang wrote:
> On Sat, Jul 15, 2017 at 04:51:26PM -0700, Guenter Roeck wrote:
> > AMD Family 17h uses the KERNCZ SMBus controller. While its documentation
> > is not publicly available, it is documented in the BIOS and Kernel
> > Developer’s Guide for AMD Family 15h Models 60h-6Fh Processors.
> >
> > On this SMBus controller, the port select register is at PMx register
> > 0x02, bit 4:3 (PMx00 register bit 20:19).
> >
> > Without this patch, the 4 SMBus channels on AMD Family 17h chips are
> > mirrored and report the same chips on all channels.
> >
> > Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx>
>
> I need input from Jean for this one.
I am getting feedback from others that both Ryzen and Threadripper CPUs are affected.
It would be great if we can find a means to move this forward or find a better fix.

Thanks,
Guenter

> > ---
> >   drivers/i2c/busses/i2c-piix4.c | 30 ++++++++++++++++++++++++++----
> >   1 file changed, 26 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-piix4.c b/drivers/i2c/busses/i2c-piix4.c
> > index 0ecdb47a23ab..01f767ee4546 100644
> > --- a/drivers/i2c/busses/i2c-piix4.c
> > +++ b/drivers/i2c/busses/i2c-piix4.c
> > @@ -94,6 +94,12 @@
> >   #define SB800_PIIX4_PORT_IDX_ALT	0x2e
> >   #define SB800_PIIX4_PORT_IDX_SEL	0x2f
> >   #define SB800_PIIX4_PORT_IDX_MASK	0x06
> > +#define SB800_PIIX4_PORT_IDX_SHIFT	1
> > +
> > +/* On kerncz, SmBus0Sel is at bit 20:19 of PMx00 DecodeEn */
> > +#define SB800_PIIX4_PORT_IDX_KERNCZ		0x02
> > +#define SB800_PIIX4_PORT_IDX_MASK_KERNCZ	0x18
> > +#define SB800_PIIX4_PORT_IDX_SHIFT_KERNCZ	3
> >   
> >   /* insmod parameters */
> >   
> > @@ -149,6 +155,8 @@ static const struct dmi_system_id piix4_dmi_ibm[] = {
> >    */
> >   static DEFINE_MUTEX(piix4_mutex_sb800);
> >   static u8 piix4_port_sel_sb800;
> > +static u8 piix4_port_mask_sb800;
> > +static u8 piix4_port_shift_sb800;
> >   static const char *piix4_main_port_names_sb800[PIIX4_MAX_ADAPTERS] = {
> >   	" port 0", " port 2", " port 3", " port 4"
> >   };
> > @@ -347,7 +355,19 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
> >   
> >   	/* Find which register is used for port selection */
> >   	if (PIIX4_dev->vendor == PCI_VENDOR_ID_AMD) {
> > -		piix4_port_sel_sb800 = SB800_PIIX4_PORT_IDX_ALT;
> > +		switch (PIIX4_dev->device) {
> > +		case PCI_DEVICE_ID_AMD_KERNCZ_SMBUS:
> > +			piix4_port_sel_sb800 = SB800_PIIX4_PORT_IDX_KERNCZ;
> > +			piix4_port_mask_sb800 = SB800_PIIX4_PORT_IDX_MASK_KERNCZ;
> > +			piix4_port_shift_sb800 = SB800_PIIX4_PORT_IDX_SHIFT_KERNCZ;
> > +			break;
> > +		case PCI_DEVICE_ID_AMD_HUDSON2_SMBUS:
> > +		default:
> > +			piix4_port_sel_sb800 = SB800_PIIX4_PORT_IDX_ALT;
> > +			piix4_port_mask_sb800 = SB800_PIIX4_PORT_IDX_MASK;
> > +			piix4_port_shift_sb800 = SB800_PIIX4_PORT_IDX_SHIFT;
> > +			break;
> > +		}
> >   	} else {
> >   		mutex_lock(&piix4_mutex_sb800);
> >   		outb_p(SB800_PIIX4_PORT_IDX_SEL, SB800_PIIX4_SMB_IDX);
> > @@ -355,6 +375,8 @@ static int piix4_setup_sb800(struct pci_dev *PIIX4_dev,
> >   		piix4_port_sel_sb800 = (port_sel & 0x01) ?
> >   				       SB800_PIIX4_PORT_IDX_ALT :
> >   				       SB800_PIIX4_PORT_IDX;
> > +		piix4_port_mask_sb800 = SB800_PIIX4_PORT_IDX_MASK;
> > +		piix4_port_shift_sb800 = SB800_PIIX4_PORT_IDX_SHIFT;
> >   		mutex_unlock(&piix4_mutex_sb800);
> >   	}
> >   
> > @@ -616,8 +638,8 @@ static s32 piix4_access_sb800(struct i2c_adapter *adap, u16 addr,
> >   	smba_en_lo = inb_p(SB800_PIIX4_SMB_IDX + 1);
> >   
> >   	port = adapdata->port;
> > -	if ((smba_en_lo & SB800_PIIX4_PORT_IDX_MASK) != port)
> > -		outb_p((smba_en_lo & ~SB800_PIIX4_PORT_IDX_MASK) | port,
> > +	if ((smba_en_lo & piix4_port_mask_sb800) != port)
> > +		outb_p((smba_en_lo & ~piix4_port_mask_sb800) | port,
> >   		       SB800_PIIX4_SMB_IDX + 1);
> >   
> >   	retval = piix4_access(adap, addr, flags, read_write,
> > @@ -706,7 +728,7 @@ static int piix4_add_adapter(struct pci_dev *dev, unsigned short smba,
> >   
> >   	adapdata->smba = smba;
> >   	adapdata->sb800_main = sb800_main;
> > -	adapdata->port = port << 1;
> > +	adapdata->port = port << piix4_port_shift_sb800;
> >   
> >   	/* set up the sysfs linkage to our parent device */
> >   	adap->dev.parent = &dev->dev;
> > --
> > 2.7.4