Re: [PATCH v3 4/4] PCI: cadence: Use "dma-ranges" instead of "cdns,no-bar-match-nbits" property
From: Kishon Vijay Abraham I
Date: Thu May 21 2020 - 08:13:21 EST
Rob,
On 5/21/2020 9:00 AM, Kishon Vijay Abraham I wrote:
> Hi Rob,
>
> On 5/19/2020 10:41 PM, Rob Herring wrote:
>> On Fri, May 8, 2020 at 7:07 AM Kishon Vijay Abraham I <kishon@xxxxxx> wrote:
>>>
>>> Cadence PCIe core driver (host mode) uses "cdns,no-bar-match-nbits"
>>> property to configure the number of bits passed through from PCIe
>>> address to internal address in Inbound Address Translation register.
>>> This only used the NO MATCH BAR.
>>>
>>> However standard PCI dt-binding already defines "dma-ranges" to
>>> describe the address ranges accessible by PCIe controller. Add support
>>> in Cadence PCIe host driver to parse dma-ranges and configure the
>>> inbound regions for BAR0, BAR1 and NO MATCH BAR. Cadence IP specifies
>>> maximum size for BAR0 as 256GB, maximum size for BAR1 as 2 GB, so if
>>> the dma-ranges specifies a size larger than the maximum allowed, the
>>> driver will split and configure the BARs.
>>
>> Would be useful to know what your dma-ranges contains now.
>>
>>
>>> Legacy device tree binding compatibility is maintained by retaining
>>> support for "cdns,no-bar-match-nbits".
>>>
>>> Signed-off-by: Kishon Vijay Abraham I <kishon@xxxxxx>
>>> ---
>>> .../controller/cadence/pcie-cadence-host.c | 141 ++++++++++++++++--
>>> drivers/pci/controller/cadence/pcie-cadence.h | 17 ++-
>>> 2 files changed, 141 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
>>> index 6ecebb79057a..2485ecd8434d 100644
>>> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
>>> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
>>> @@ -11,6 +11,12 @@
>>>
>>> #include "pcie-cadence.h"
>>>
>>> +static u64 cdns_rp_bar_max_size[] = {
>>> + [RP_BAR0] = _ULL(128 * SZ_2G),
>>> + [RP_BAR1] = SZ_2G,
>>> + [RP_NO_BAR] = SZ_64T,
>>> +};
>>> +
>>> void __iomem *cdns_pci_map_bus(struct pci_bus *bus, unsigned int devfn,
>>> int where)
>>> {
>>> @@ -106,6 +112,117 @@ static int cdns_pcie_host_init_root_port(struct cdns_pcie_rc *rc)
>>> return 0;
>>> }
>>>
>>> +static void cdns_pcie_host_bar_ib_config(struct cdns_pcie_rc *rc,
>>> + enum cdns_pcie_rp_bar bar,
>>> + u64 cpu_addr, u32 aperture)
>>> +{
>>> + struct cdns_pcie *pcie = &rc->pcie;
>>> + u32 addr0, addr1;
>>> +
>>> + addr0 = CDNS_PCIE_AT_IB_RP_BAR_ADDR0_NBITS(aperture) |
>>> + (lower_32_bits(cpu_addr) & GENMASK(31, 8));
>>> + addr1 = upper_32_bits(cpu_addr);
>>> + cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_RP_BAR_ADDR0(bar), addr0);
>>> + cdns_pcie_writel(pcie, CDNS_PCIE_AT_IB_RP_BAR_ADDR1(bar), addr1);
>>> +}
>>> +
>>> +static int cdns_pcie_host_bar_config(struct cdns_pcie_rc *rc,
>>> + struct resource_entry *entry,
>>> + enum cdns_pcie_rp_bar *index)
>>> +{
>>> + u64 cpu_addr, pci_addr, size, winsize;
>>> + struct cdns_pcie *pcie = &rc->pcie;
>>> + struct device *dev = pcie->dev;
>>> + enum cdns_pcie_rp_bar bar;
>>> + unsigned long flags;
>>> + u32 aperture;
>>> + u32 value;
>>> +
>>> + cpu_addr = entry->res->start;
>>> + flags = entry->res->flags;
>>> + pci_addr = entry->res->start - entry->offset;
>>> + size = resource_size(entry->res);
>>> + bar = *index;
>>> +
>>> + if (entry->offset) {
>>> + dev_err(dev, "Cannot map PCI addr: %llx to CPU addr: %llx\n",
>>> + pci_addr, cpu_addr);
>>
>> Would be a bit more clear to say PCI addr must equal CPU addr.
>>
>>> + return -EINVAL;
>>> + }
>>> +
>>> + value = cdns_pcie_readl(pcie, CDNS_PCIE_LM_RC_BAR_CFG);
>>> + while (size > 0) {
>>> + if (bar > RP_NO_BAR) {
>>> + dev_err(dev, "Failed to map inbound regions!\n");
>>> + return -EINVAL;
>>> + }
>>> +
>>> + winsize = size;
>>> + if (size > cdns_rp_bar_max_size[bar])
>>> + winsize = cdns_rp_bar_max_size[bar];
>>> +
>>> + aperture = ilog2(winsize);
>>> +
>>> + cdns_pcie_host_bar_ib_config(rc, bar, cpu_addr, aperture);
>>> +
>>> + if (bar == RP_NO_BAR)
>>> + break;
>>> +
>>> + if (winsize + cpu_addr >= SZ_4G) {
>>> + if (!(flags & IORESOURCE_PREFETCH))
>>> + value |= LM_RC_BAR_CFG_CTRL_MEM_64BITS(bar);
>>> + value |= LM_RC_BAR_CFG_CTRL_PREF_MEM_64BITS(bar);
>>> + } else {
>>> + if (!(flags & IORESOURCE_PREFETCH))
>>> + value |= LM_RC_BAR_CFG_CTRL_MEM_32BITS(bar);
>>> + value |= LM_RC_BAR_CFG_CTRL_PREF_MEM_32BITS(bar);
>>> + }
>>> +
>>> + value |= LM_RC_BAR_CFG_APERTURE(bar, aperture);
>>> +
>>> + size -= winsize;
>>> + cpu_addr += winsize;
>>> + bar++;
>>> + }
>>> + cdns_pcie_writel(pcie, CDNS_PCIE_LM_RC_BAR_CFG, value);
>>> + *index = bar;
>>> +
>>> + return 0;
>>> +}
>>> +
>>> +static int cdns_pcie_host_map_dma_ranges(struct cdns_pcie_rc *rc)
>>> +{
>>> + enum cdns_pcie_rp_bar bar = RP_BAR0;
>>> + struct cdns_pcie *pcie = &rc->pcie;
>>> + struct device *dev = pcie->dev;
>>> + struct device_node *np = dev->of_node;
>>> + struct pci_host_bridge *bridge;
>>> + struct resource_entry *entry;
>>> + u32 no_bar_nbits = 32;
>>> + int err;
>>> +
>>> + bridge = pci_host_bridge_from_priv(rc);
>>> + if (!bridge)
>>> + return -ENOMEM;
>>> +
>>> + if (list_empty(&bridge->dma_ranges)) {
>>> + of_property_read_u32(np, "cdns,no-bar-match-nbits",
>>> + &no_bar_nbits);
>>> + cdns_pcie_host_bar_ib_config(rc, RP_NO_BAR, 0x0, no_bar_nbits);
>>> + return 0;
>>> + }
>>> +
>>> + resource_list_for_each_entry(entry, &bridge->dma_ranges) {
>>> + err = cdns_pcie_host_bar_config(rc, entry, &bar);
>>
>> Seems like this should have some better logic to pick which BAR to
>> use. Something like find the biggest region and then find the smallest
>> BAR that it fits in. Then get the next biggest...
>
> Okay, I'll change this something like for each region, find the smallest BAR
> that it fits in and if there is no BAR big enough to hold the region, split the
> region to see if can be fitted using multiple BARs. I don't see the purpose of
> finding the biggest region first since at all times we'll only use the smallest
> BAR to fit.
Nevermind, I realized finding the biggest region is useful. I have sent a patch
adding support for that.
Thanks
Kishon