On Fri, Apr 12, 2019 at 04:07:49PM +0530, Kishon Vijay Abraham I wrote: > Hi Lorenzo, > > On 11/04/19 9:02 PM, Lorenzo Pieralisi wrote: > > On Mon, Mar 25, 2019 at 03:09:39PM +0530, Kishon Vijay Abraham I wrote: > >> Modify pci_epf_alloc_space API to take alignment size as argument in > >> order to argument in order to allocate aligned buffers to be mapped to > >> BARs. > >> > >> Add 'align' parameter to epc_features which can be used by platform > >> drivers to specifiy the BAR allocation alignment requirements and use > >> this while invoking pci_epf_alloc_space. > >> > >> This is mainly required for Synopsys Designware PCIe core which masks > >> the lower bits based on the BAR size (See "I/O and MEM Match Modes" > >> section in DesignWare Cores PCI Express Controller Databook version > >> 4.90a). > > > > Hi Kishon, > > > > isn't this a generic PCI BAR requirement rather than a Designware > > specific one ? > > > > The patch is fine I just would like to understand the statement above. > > The address that is allocated using pci_epf_alloc_space would be directly > written to the target address of the Inbound address translation unit. > Designware IP has a configuration parameter (CX_ATU_MIN_REGION_SIZE [1]) which > has 64KB as default value and the lower 16 bits of the Base, Limit and Target > registers of the Inbound ATU are fixed to zero. So if the programmed memory > address is not aligned to 64 KB boundary there will be memory corruption. > > PCI spec has restrictions on the minimum memory address range requested by BAR > as 128 Bytes and the size to be a power of 2, however it doesn't have any > restriction on the local endpoint memory addresses that are mapped to BAR. That > is an endpoint controller restriction. > > [1] -> http://www.ti.com/lit/ug/spruid7c/spruid7c.pdf That's much clearer, it should go into the commit log, I will try to update it myself and notify you when I push it out. Lorenzo > Thanks > Kishon > > > Thanks, > > Lorenzo > > > >> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx> > >> --- > >> drivers/pci/endpoint/functions/pci-epf-test.c | 5 +++-- > >> drivers/pci/endpoint/pci-epf-core.c | 10 ++++++++-- > >> include/linux/pci-epc.h | 2 ++ > >> include/linux/pci-epf.h | 3 ++- > >> 4 files changed, 15 insertions(+), 5 deletions(-) > >> > >> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c > >> index d0b91da49bf4..c0786ca74312 100644 > >> --- a/drivers/pci/endpoint/functions/pci-epf-test.c > >> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c > >> @@ -438,7 +438,7 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf) > >> epc_features = epf_test->epc_features; > >> > >> base = pci_epf_alloc_space(epf, sizeof(struct pci_epf_test_reg), > >> - test_reg_bar); > >> + test_reg_bar, epc_features->align); > >> if (!base) { > >> dev_err(dev, "Failed to allocated register space\n"); > >> return -ENOMEM; > >> @@ -453,7 +453,8 @@ static int pci_epf_test_alloc_space(struct pci_epf *epf) > >> if (!!(epc_features->reserved_bar & (1 << bar))) > >> continue; > >> > >> - base = pci_epf_alloc_space(epf, bar_size[bar], bar); > >> + base = pci_epf_alloc_space(epf, bar_size[bar], bar, > >> + epc_features->align); > >> if (!base) > >> dev_err(dev, "Failed to allocate space for BAR%d\n", > >> bar); > >> diff --git a/drivers/pci/endpoint/pci-epf-core.c b/drivers/pci/endpoint/pci-epf-core.c > >> index 8bfdcd291196..fb1306de8f40 100644 > >> --- a/drivers/pci/endpoint/pci-epf-core.c > >> +++ b/drivers/pci/endpoint/pci-epf-core.c > >> @@ -109,10 +109,12 @@ EXPORT_SYMBOL_GPL(pci_epf_free_space); > >> * pci_epf_alloc_space() - allocate memory for the PCI EPF register space > >> * @size: the size of the memory that has to be allocated > >> * @bar: the BAR number corresponding to the allocated register space > >> + * @align: alignment size for the allocation region > >> * > >> * Invoke to allocate memory for the PCI EPF register space. > >> */ > >> -void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar) > >> +void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, > >> + size_t align) > >> { > >> void *space; > >> struct device *dev = epf->epc->dev.parent; > >> @@ -120,7 +122,11 @@ void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar) > >> > >> if (size < 128) > >> size = 128; > >> - size = roundup_pow_of_two(size); > >> + > >> + if (align) > >> + size = ALIGN(size, align); > >> + else > >> + size = roundup_pow_of_two(size); > >> > >> space = dma_alloc_coherent(dev, size, &phys_addr, GFP_KERNEL); > >> if (!space) { > >> diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h > >> index c3ffa3917f88..f641badc2c61 100644 > >> --- a/include/linux/pci-epc.h > >> +++ b/include/linux/pci-epc.h > >> @@ -109,6 +109,7 @@ struct pci_epc { > >> * @reserved_bar: bitmap to indicate reserved BAR unavailable to function driver > >> * @bar_fixed_64bit: bitmap to indicate fixed 64bit BARs > >> * @bar_fixed_size: Array specifying the size supported by each BAR > >> + * @align: alignment size required for BAR buffer allocation > >> */ > >> struct pci_epc_features { > >> unsigned int linkup_notifier : 1; > >> @@ -117,6 +118,7 @@ struct pci_epc_features { > >> u8 reserved_bar; > >> u8 bar_fixed_64bit; > >> u64 bar_fixed_size[BAR_5 + 1]; > >> + size_t align; > >> }; > >> > >> #define to_pci_epc(device) container_of((device), struct pci_epc, dev) > >> diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h > >> index ec02f58758c8..2d6f07556682 100644 > >> --- a/include/linux/pci-epf.h > >> +++ b/include/linux/pci-epf.h > >> @@ -149,7 +149,8 @@ void pci_epf_destroy(struct pci_epf *epf); > >> int __pci_epf_register_driver(struct pci_epf_driver *driver, > >> struct module *owner); > >> void pci_epf_unregister_driver(struct pci_epf_driver *driver); > >> -void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar); > >> +void *pci_epf_alloc_space(struct pci_epf *epf, size_t size, enum pci_barno bar, > >> + size_t align); > >> void pci_epf_free_space(struct pci_epf *epf, void *addr, enum pci_barno bar); > >> int pci_epf_bind(struct pci_epf *epf); > >> void pci_epf_unbind(struct pci_epf *epf); > >> -- > >> 2.17.1 > >>
