Re: [PATCH V4 06/16] PCI: dwc: Add ext config space capability search API

Vidya Sagar
2019-04-24T03:12:30Z

On 4/24/2019 2:05 AM, Bjorn Helgaas wrote:
> On Tue, Apr 23, 2019 at 01:57:20PM +0530, Vidya Sagar wrote:
>> Add extended configuration space capability search API using struct dw_pcie *
>> pointer
>>
>> Signed-off-by: Vidya Sagar <vidyas@nvidia.com>
>> Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
>> ---
>> Changes from [v3]:
>> * None
>>
>> Changes from [v2]:
>> * None
>>
>> Changes from [v1]:
>> * This is a new patch in v2 series
>>
>> drivers/pci/controller/dwc/pcie-designware.c | 41 ++++++++++++++++++++
>> drivers/pci/controller/dwc/pcie-designware.h | 1 +
>> 2 files changed, 42 insertions(+)
>>
>> diff --git a/drivers/pci/controller/dwc/pcie-designware.c b/drivers/pci/controller/dwc/pcie-designware.c
>> index 6a98135244d6..ecf5fe8842f6 100644
>> --- a/drivers/pci/controller/dwc/pcie-designware.c
>> +++ b/drivers/pci/controller/dwc/pcie-designware.c
>> @@ -53,6 +53,47 @@ u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap)
>> return __dw_pcie_find_next_cap(pci, next_cap_ptr, cap);
>> }
>>
>
> Please make sure there's a comment here about why
> pci_find_ext_capability() can't be used (a comment covering both this
> and pci_find_capability() is fine, if the reason is the same).
Reason is same that standard pci_find_ext_capability() uses 'struct pci_dev *dev' pointer
and can only be used post enumeration whereas APIs being added here use 'struct dw_pcie *pci'
and can be used before link up also.
I'll add a comment in the other patch where I'm moving these APIs from pcie-designware-ep.c file
to pcie-designware.c file.

>
>> +static int dw_pcie_find_next_ext_capability(struct dw_pcie *pci, int start,
>> + int cap)
>> +{
>> + u32 header;
>> + int ttl;
>> + int pos = PCI_CFG_SPACE_SIZE;
>> +
>> + /* minimum 8 bytes per capability */
>> + ttl = (PCI_CFG_SPACE_EXP_SIZE - PCI_CFG_SPACE_SIZE) / 8;
>> +
>> + if (start)
>> + pos = start;
>> +
>> + header = dw_pcie_readl_dbi(pci, pos);
>> + /*
>> + * If we have no capabilities, this is indicated by cap ID,
>> + * cap version and next pointer all being 0.
>> + */
>> + if (header == 0)
>> + return 0;
>> +
>> + while (ttl-- > 0) {
>> + if (PCI_EXT_CAP_ID(header) == cap && pos != start)
>> + return pos;
>> +
>> + pos = PCI_EXT_CAP_NEXT(header);
>> + if (pos < PCI_CFG_SPACE_SIZE)
>> + break;
>> +
>> + header = dw_pcie_readl_dbi(pci, pos);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +int dw_pcie_find_ext_capability(struct dw_pcie *pci, int cap)
>> +{
>> + return dw_pcie_find_next_ext_capability(pci, 0, cap);
>> +}
>> +EXPORT_SYMBOL_GPL(dw_pcie_find_ext_capability);
>> +
>> int dw_pcie_read(void __iomem *addr, int size, u32 *val)
>> {
>> if (!IS_ALIGNED((uintptr_t)addr, size)) {
>> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
>> index 35160b4ce929..67307842e003 100644
>> --- a/drivers/pci/controller/dwc/pcie-designware.h
>> +++ b/drivers/pci/controller/dwc/pcie-designware.h
>> @@ -249,6 +249,7 @@ struct dw_pcie {
>> container_of((endpoint), struct dw_pcie, ep)
>>
>> u8 dw_pcie_find_capability(struct dw_pcie *pci, u8 cap);
>> +int dw_pcie_find_ext_capability(struct dw_pcie *pci, int cap);
>>
>> int dw_pcie_read(void __iomem *addr, int size, u32 *val);
>> int dw_pcie_write(void __iomem *addr, int size, u32 val);
>> --
>> 2.17.1
>>