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

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Message-ID: <0ec731d7-16c5-9303-b528-fd795b0f65be@roeck-us.net>
Date:   Fri, 22 Sep 2017 15:41:39 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Wolfram Sang <wsa@...-dreams.de>
Cc:     Jean Delvare <jdelvare@...e.com>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] i2c: piix4: Fix SMBus port selection for AMD Family 17h
 chips

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@...ck-us.net>
> 
> 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
>>