Re: [RFC PATCH 3/9] PCI/portdrv: Add pcie_walk_rcec() to walk RCiEPs associated with RCEC

Jonathan Cameron
2020-07-27T10:50:59Z

On Fri, 24 Jul 2020 10:22:17 -0700
Sean V Kelley <sean.v.kelley@intel.com> wrote:

> From: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
>
> When an RCEC device signals error(s) to a CPU core, the CPU core
> needs to walk all the RCiEPs associated with that RCEC to check
> errors. So add the function pcie_walk_rcec() to walk all RCiEPs
> associated with the RCEC device.
>
> Co-developed-by: Sean V Kelley <sean.v.kelley@intel.com>
> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
> Signed-off-by: Sean V Kelley <sean.v.kelley@intel.com>

A few trivial points inline. With those tidied up.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
> drivers/pci/pcie/portdrv.h | 2 +
> drivers/pci/pcie/portdrv_core.c | 82 +++++++++++++++++++++++++++++++++
> 2 files changed, 84 insertions(+)
>
> diff --git a/drivers/pci/pcie/portdrv.h b/drivers/pci/pcie/portdrv.h
> index af7cf237432a..c11d5ecbad76 100644
> --- a/drivers/pci/pcie/portdrv.h
> +++ b/drivers/pci/pcie/portdrv.h
> @@ -116,6 +116,8 @@ void pcie_port_service_unregister(struct pcie_port_service_driver *new);
>
> extern struct bus_type pcie_port_bus_type;
> int pcie_port_device_register(struct pci_dev *dev);
> +void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
> + void *userdata);
> #ifdef CONFIG_PM
> int pcie_port_device_suspend(struct device *dev);
> int pcie_port_device_resume_noirq(struct device *dev);
> diff --git a/drivers/pci/pcie/portdrv_core.c b/drivers/pci/pcie/portdrv_core.c
> index 50a9522ab07d..bdcbb34764c2 100644
> --- a/drivers/pci/pcie/portdrv_core.c
> +++ b/drivers/pci/pcie/portdrv_core.c
> @@ -14,6 +14,7 @@
> #include <linux/pm_runtime.h>
> #include <linux/string.h>
> #include <linux/slab.h>
> +#include <linux/bitops.h>
> #include <linux/aer.h>
>
> #include "../pci.h"
> @@ -365,6 +366,87 @@ int pcie_port_device_register(struct pci_dev *dev)
> return status;
> }
>
> +static int pcie_walk_rciep_devfn(struct pci_bus *pbus, int (*cb)(struct pci_dev *, void *),
> + void *userdata, unsigned long bitmap)
> +{
> + unsigned int dev, fn;
> + struct pci_dev *pdev;
> + int retval;
> +
> + for_each_set_bit(dev, &bitmap, 32) {
> + for (fn = 0; fn < 8; fn++) {
> + pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn));
> +
> + if (!pdev || pci_pcie_type(pdev) != PCI_EXP_TYPE_RC_END)
> + continue;
> +
> + retval = cb(pdev, userdata);
> + if (retval)
> + return retval;
> + }
> + }
> +
> + return 0;
> +}
> +
> +/** pcie_walk_rcec - Walk RCiEP devices associating with RCEC and call callback.

/**
* pcie...

> + * @rcec RCEC whose RCiEP devices should be walked.
> + * @cb Callback to be called for each RCiEP device found.
> + * @userdata Arbitrary pointer to be passed to callback.
> + *
> + * Walk the given RCEC. Call the provided callback on each RCiEP device found.
> + *
> + * We check the return of @cb each time. If it returns anything
> + * other than 0, we break out.
> + *
> + */
> +void pcie_walk_rcec(struct pci_dev *rcec, int (*cb)(struct pci_dev *, void *),
> + void *userdata)
> +{
> + u32 pos, bitmap, hdr, busn;
> + u8 ver, nextbusn, lastbusn;
> + struct pci_bus *pbus;
> + unsigned int bnr;
> +
> + pos = pci_find_ext_capability(rcec, PCI_EXT_CAP_ID_RCEC);
> + if (!pos)
> + return;
> +
> + pbus = pci_find_bus(pci_domain_nr(rcec->bus), rcec->bus->number);
> + if (!pbus)
> + return;
> +
> + pci_read_config_dword(rcec, pos + PCI_RCEC_RCIEP_BITMAP, &bitmap);
> +
> + /* Find RCiEP devices on the same bus as the RCEC */
> + if (pcie_walk_rciep_devfn(pbus, cb, userdata, (unsigned long)bitmap))
> + return;
> +
> + /* Check whether RCEC BUSN register is present */
> + pci_read_config_dword(rcec, pos, &hdr);
> + ver = PCI_EXT_CAP_VER(hdr);
> + if (ver < PCI_RCEC_BUSN_REG_VER)
> + return;
> +
> + pci_read_config_dword(rcec, pos + PCI_RCEC_BUSN, &busn);
> + nextbusn = PCI_RCEC_BUSN_NEXT(busn);
> + lastbusn = PCI_RCEC_BUSN_LAST(busn);
> +
> + /* All RCiEP devices are on the same bus as the RCEC */
> + if (nextbusn == 0xff && lastbusn == 0x00)
> + return;
> +
> + for (bnr = nextbusn; bnr < (lastbusn + 1); bnr++) {

Why not bnr <= lastbusn? Seems more intuitive way of making it clear the
range is inclusive.

> + pbus = pci_find_bus(pci_domain_nr(rcec->bus), bnr);
> + if (!pbus)
> + continue;
> +
> + /* Find RCiEP devices on the given bus */
> + if (pcie_walk_rciep_devfn(pbus, cb, userdata, 0xffffffff))
> + return;
> + }
> +}
> +
> #ifdef CONFIG_PM
> typedef int (*pcie_pm_callback_t)(struct pcie_device *);
>