Re: [PATCH v1 7/7] i2c: i801: convert to use common P2SB accessor

Jean Delvare
2021-03-10T14:52:45Z

Hi Andy,

On Mon, 8 Mar 2021 14:20:20 +0200, Andy Shevchenko wrote:
> Since we have a common P2SB accessor in tree we may use it instead of
> open coded variants.
>
> Replace custom code by pci_p2sb_bar() call.

I like the idea. Just two things...

> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> drivers/i2c/busses/Kconfig | 1 +
> drivers/i2c/busses/i2c-i801.c | 40 ++++++++---------------------------
> drivers/pci/pci-p2sb.c | 6 ++++++
> 3 files changed, 16 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 05ebf7546e3f..ffd3007f888c 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -101,6 +101,7 @@ config I2C_HIX5HD2
> config I2C_I801
> tristate "Intel 82801 (ICH/PCH)"
> depends on PCI
> + select PCI_P2SB if X86
> select CHECK_SIGNATURE if X86 && DMI
> select I2C_SMBUS
> help
> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
> index 4acee6f9e5a3..23b43de9786a 100644
> --- a/drivers/i2c/busses/i2c-i801.c
> +++ b/drivers/i2c/busses/i2c-i801.c
> @@ -90,6 +90,7 @@
> #include <linux/interrupt.h>
> #include <linux/module.h>
> #include <linux/pci.h>
> +#include <linux/pci-p2sb.h>
> #include <linux/kernel.h>
> #include <linux/stddef.h>
> #include <linux/delay.h>
> @@ -136,7 +137,6 @@
> #define TCOBASE 0x050
> #define TCOCTL 0x054
>
> -#define SBREG_BAR 0x10
> #define SBREG_SMBCTRL 0xc6000c
> #define SBREG_SMBCTRL_DNV 0xcf000c
>
> @@ -1524,52 +1524,30 @@ static const struct itco_wdt_platform_data spt_tco_platform_data = {
> .version = 4,
> };
>
> -static DEFINE_SPINLOCK(p2sb_spinlock);
> -
> static struct platform_device *
> i801_add_tco_spt(struct i801_priv *priv, struct pci_dev *pci_dev,
> struct resource *tco_res)
> {
> struct resource *res;
> unsigned int devfn;
> - u64 base64_addr;
> - u32 base_addr;
> - u8 hidden;
> + int ret;
>
> /*
> * We must access the NO_REBOOT bit over the Primary to Sideband
> - * bridge (P2SB). The BIOS prevents the P2SB device from being
> - * enumerated by the PCI subsystem, so we need to unhide/hide it
> - * to lookup the P2SB BAR.
> + * bridge (P2SB).
> */
> - spin_lock(&p2sb_spinlock);
>
> devfn = PCI_DEVFN(PCI_SLOT(pci_dev->devfn), 1);
>
> - /* Unhide the P2SB device, if it is hidden */
> - pci_bus_read_config_byte(pci_dev->bus, devfn, 0xe1, &hidden);
> - if (hidden)
> - pci_bus_write_config_byte(pci_dev->bus, devfn, 0xe1, 0x0);
> -
> - pci_bus_read_config_dword(pci_dev->bus, devfn, SBREG_BAR, &base_addr);
> - base64_addr = base_addr & 0xfffffff0;
> -
> - pci_bus_read_config_dword(pci_dev->bus, devfn, SBREG_BAR + 0x4, &base_addr);
> - base64_addr |= (u64)base_addr << 32;
> -
> - /* Hide the P2SB device, if it was hidden before */
> - if (hidden)
> - pci_bus_write_config_byte(pci_dev->bus, devfn, 0xe1, hidden);
> - spin_unlock(&p2sb_spinlock);
> -
> res = &tco_res[1];
> + ret = pci_p2sb_bar(pci_dev, devfn, res);
> + if (ret)
> + return ERR_PTR(ret);
> +
> if (pci_dev->device == PCI_DEVICE_ID_INTEL_DNV_SMBUS)
> - res->start = (resource_size_t)base64_addr + SBREG_SMBCTRL_DNV;
> + res->start += SBREG_SMBCTRL_DNV;
> else
> - res->start = (resource_size_t)base64_addr + SBREG_SMBCTRL;
> -
> - res->end = res->start + 3;
> - res->flags = IORESOURCE_MEM;
> + res->start += SBREG_SMBCTRL;

I can't see why you no longer set res->end and res->flags here. I can
imagine that pci_p2sb_bar() may have set the flags for us, but not that
->end is still correct after you fixed up ->start. Am I missing
something?

>
> return platform_device_register_resndata(&pci_dev->dev, "iTCO_wdt", -1,
> tco_res, 2, &spt_tco_platform_data,
> diff --git a/drivers/pci/pci-p2sb.c b/drivers/pci/pci-p2sb.c
> index 68d7dad48cdb..7f6bc7d4482a 100644
> --- a/drivers/pci/pci-p2sb.c
> +++ b/drivers/pci/pci-p2sb.c
> @@ -22,6 +22,12 @@
>
> static const struct x86_cpu_id p2sb_cpu_ids[] = {
> X86_MATCH_INTEL_FAM6_MODEL(ATOM_GOLDMONT, PCI_DEVFN(13, 0)),
> + X86_MATCH_INTEL_FAM6_MODEL(ATOM_GOLDMONT_D, PCI_DEVFN(31, 1)),
> + X86_MATCH_INTEL_FAM6_MODEL(ATOM_SILVERMONT_D, PCI_DEVFN(31, 1)),
> + X86_MATCH_INTEL_FAM6_MODEL(KABYLAKE, PCI_DEVFN(31, 1)),
> + X86_MATCH_INTEL_FAM6_MODEL(KABYLAKE_L, PCI_DEVFN(31, 1)),
> + X86_MATCH_INTEL_FAM6_MODEL(SKYLAKE, PCI_DEVFN(31, 1)),
> + X86_MATCH_INTEL_FAM6_MODEL(SKYLAKE_L, PCI_DEVFN(31, 1)),
> {}
> };
>

Any reason why this is added in this patch instead of [3/7] (PCI: New
Primary to Sideband (P2SB) bridge support library)?

--
Jean Delvare
SUSE L3 Support