linux-kernel - Re: [PATCH V2 3/9] PCI/portdrv: Add pcie_walk_rcec() to walk RCiEPs associated with RCEC

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Date:   Wed, 26 Aug 2020 09:20:09 -0700
From:   "Kuppuswamy, Sathyanarayanan" 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>
To:     Sean V Kelley <sean.v.kelley@...el.com>, bhelgaas@...gle.com,
        Jonathan.Cameron@...wei.com, rjw@...ysocki.net,
        ashok.raj@...el.com, tony.luck@...el.com
Cc:     linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        Qiuxu Zhuo <qiuxu.zhuo@...el.com>
Subject: Re: [PATCH V2 3/9] PCI/portdrv: Add pcie_walk_rcec() to walk RCiEPs
 associated with RCEC



On 8/4/20 12:40 PM, Sean V Kelley wrote:
> From: Qiuxu Zhuo <qiuxu.zhuo@...el.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.
I think its better if you merge the usage patch and API
(pcie_walk_rcec) patch together.

Did you not get unused function warning with this patch?
> 
> Co-developed-by: Sean V Kelley <sean.v.kelley@...el.com>
> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@...el.com>
> Signed-off-by: Sean V Kelley <sean.v.kelley@...el.com>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@...wei.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 5d4a400094fc..daa2dfa83a0b 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.
> + * @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; bnr++) {
> +		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 *);
>   
> 

-- 
Sathyanarayanan Kuppuswamy
Linux Kernel Developer