[Skiboot] [PATCH RESEND v3 3/5] core/pci: Create the struct pci_device nodes automatically

[Oliver O'Halloran]

On Fri, Oct 25, 2019 at 5:03 AM Sergey Miroshnichenko
<s.miroshnichenko at yadro.com> wrote:
>
> Currently the struct pci_device nodes are created only during the bus
> rescan in skiboot (pci_scan_bus) initiated by an OS via OPAL. But these
> structures also could be created if reading the configuration space via
> OPAL reveals a new hotplugged device.

What happens on hot-remove? I'd rather not leave around pci_device's
with no corresponding physical device since that's just leaving a
land-mine for someone else to step on.

> This will allow using the standard platform-independent PCIe hotplug driver
> in Linux kernel ("pciehp") instead of requesting a Device Tree update.

Why *exactly* is this required?

My best guess is that we're relying on skiboot to re-initialise
topology after a reset, but if we want to get away from using pnv_php
then I think we would be better off handling that in the kernel.

> Signed-off-by: Sergey Miroshnichenko <s.miroshnichenko at yadro.com>
> ---
>  core/pci-opal.c | 23 +++++++++++++++++++----
>  1 file changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/core/pci-opal.c b/core/pci-opal.c
> index 828ce8a9..a3f1b71d 100644
> --- a/core/pci-opal.c
> +++ b/core/pci-opal.c
> @@ -14,13 +14,21 @@
>  #include <timebase.h>
>  #include <timer.h>
>
> +static struct pci_device *pci_create_dn(struct phb *phb, uint16_t bdfn)
> +{
> +       struct pci_device *parent = pci_find_parent_dev(phb, bdfn);
> +
> +       return pci_scan_one(phb, parent, bdfn);
> +}
> +
>  #define OPAL_PCICFG_ACCESS_READ(op, cb, type)  \
>  static int64_t opal_pci_config_##op(uint64_t phb_id,                   \
>                                     uint64_t bus_dev_func,              \
> -                                   uint64_t offset, type data)         \
> +                                   uint64_t offset, type *data)        \
>  {                                                                      \
>         struct phb *phb = pci_get_phb(phb_id);                          \
>         int64_t rc;                                                     \
> +       bool dev_found;                                                 \
>                                                                         \
>         if (!opal_addr_valid((void *)data))                             \
>                 return OPAL_PARAMETER;                                  \
> @@ -28,7 +36,14 @@ static int64_t opal_pci_config_##op(uint64_t phb_id,                 \
>         if (!phb)                                                       \
>                 return OPAL_PARAMETER;                                  \
>         phb_lock(phb);                                                  \
> +                                                                       \
> +       dev_found = pci_find_dev_safe(phb, bus_dev_func);               \
> +                                                                       \
>         rc = phb->ops->cfg_##cb(phb, bus_dev_func, offset, data);       \
> +                                                                       \
> +       if (!rc && !dev_found && *data != (type)0xffffffff)             \
> +               pci_create_dn(phb, bus_dev_func);                       \
> +                                                                       \
>         phb_unlock(phb);                                                \
>                                                                         \
>         return rc;                                                      \
> @@ -51,9 +66,9 @@ static int64_t opal_pci_config_##op(uint64_t phb_id,                  \
>         return rc;                                                      \
>  }
>
> -OPAL_PCICFG_ACCESS_READ(read_byte,             read8, uint8_t *)
> -OPAL_PCICFG_ACCESS_READ(read_half_word,                read16, uint16_t *)
> -OPAL_PCICFG_ACCESS_READ(read_word,             read32, uint32_t *)
> +OPAL_PCICFG_ACCESS_READ(read_byte,             read8, uint8_t)
> +OPAL_PCICFG_ACCESS_READ(read_half_word,                read16, uint16_t)
> +OPAL_PCICFG_ACCESS_READ(read_word,             read32, uint32_t)
>  OPAL_PCICFG_ACCESS_WRITE(write_byte,           write8, uint8_t)
>  OPAL_PCICFG_ACCESS_WRITE(write_half_word,      write16, uint16_t)
>  OPAL_PCICFG_ACCESS_WRITE(write_word,           write32, uint32_t)
> --
> 2.23.0
>