The PMU can monitor traffic of certain target Root Port or downstream
target Endpoint. User can specify the target filter by the "port" or
"bdf" option respectively. The PMU can only monitor the Root Port or
Endpoint on the same PCIe core so the value of "port" or "bdf" should
be valid and will be checked by the driver.

Currently at least and only one of "port" and "bdf" option must be set.
If "port" filter is not set or is set explicitly to zero (default),
driver will regard the user specifies a "bdf" option since "port" option
is a bitmask of the target Root Ports and zero is not a valid
value.

If user not explicitly set "port" or "bdf" filter, the driver uses "bdf"
default value (zero) to set target filter, but driver will skip the
check of bdf=0, although it's a valid value (meaning 0000:000:00.0).
Then the user just gets zero.

Therefore, we need to check if both "port" and "bdf" are invalid, then
return failure and report warning.

Testing:
before the patch:
                   0      hisi_pcie0_core1/rx_mrd_flux/
                   0      hisi_pcie0_core1/rx_mrd_flux,port=0/
              24,124      hisi_pcie0_core1/rx_mrd_flux,port=1/
                   0      hisi_pcie0_core1/rx_mrd_flux,bdf=0/
                   0      hisi_pcie0_core1/rx_mrd_flux,port=0x800/
     <not supported>      hisi_pcie0_core1/rx_mrd_flux,bdf=1/
              24,132      hisi_pcie0_core1/rx_mrd_flux,bdf=0x1700/
     <not supported>      hisi_pcie0_core1/rx_mrd_flux,port=0x0,bdf=0x0/
     <not supported>      hisi_pcie0_core1/rx_mrd_flux,port=0x0,bdf=0x1/
              24,138      hisi_pcie0_core1/rx_mrd_flux,port=0x0,bdf=0x1700/
              24,126      hisi_pcie0_core1/rx_mrd_flux,port=0x1,bdf=0x0/

after the patch:
     <not supported>      hisi_pcie0_core1/rx_mrd_flux/
     <not supported>      hisi_pcie0_core1/rx_mrd_flux,port=0/
              24,153      hisi_pcie0_core1/rx_mrd_flux,port=1/
                   0      hisi_pcie0_core1/rx_mrd_flux,port=0x800/
     <not supported>      hisi_pcie0_core1/rx_mrd_flux,bdf=0/
     <not supported>      hisi_pcie0_core1/rx_mrd_flux,bdf=1/
              24,117      hisi_pcie0_core1/rx_mrd_flux,bdf=0x1700/
     <not supported>      hisi_pcie0_core1/rx_mrd_flux,port=0x0,bdf=0x0/
     <not supported>      hisi_pcie0_core1/rx_mrd_flux,port=0x0,bdf=0x1/
              24,120      hisi_pcie0_core1/rx_mrd_flux,port=0x0,bdf=0x1700/
              24,123      hisi_pcie0_core1/rx_mrd_flux,port=0x1,bdf=0x0/
Signed-off-by: Junhao He <hejunhao3@huawei.com>
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/20240223103359.18669-6-yangyicong@huawei.comSigned-off-by: Will Deacon <will@kernel.org>