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

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Date:   Sat, 12 Aug 2017 13:33:57 +0200
From:   Wolfram Sang <wsa@...-dreams.de>
To:     Guenter Roeck <linux@...ck-us.net>
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 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.

> ---
>  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
> 

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