Messages in this thread | | | Date | Mon, 24 Oct 2022 14:24:54 -0700 | From | Dan Williams <> | Subject | Re: [PATCH v2 06/12] cxl/acpi: Extract component registers of restricted hosts from RCRB |
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Robert Richter wrote: > On 20.10.22 22:17:07, Dan Williams wrote: > > Robert Richter wrote: > > > A downstream port must be connected to a component register block. > > > For restricted hosts the base address is determined from the RCRB. The > > > RCRB is provided by the host's CEDT CHBS entry. Rework CEDT parser to > > > get the RCRB and add code to extract the component register block from > > > it. > > > > > > RCRB's BAR[0..1] point to the component block containing CXL subsystem > > > component registers. MEMBAR extraction follows the PCI base spec here, > > > esp. 64 bit extraction and memory range alignment (6.0, 7.5.1.2.1). > > > > > > Note: Right now the component register block is used for HDM decoder > > > capability only which is optional for RCDs. If unsupported by the RCD, > > > the HDM init will fail. It is future work to bypass it in this case. > > > > > > Signed-off-by: Terry Bowman <terry.bowman@amd.com> > > > Signed-off-by: Robert Richter <rrichter@amd.com> > > > --- > > > drivers/cxl/acpi.c | 79 ++++++++++++++++++++++++++++++++++++++++------ > > > 1 file changed, 69 insertions(+), 10 deletions(-) > > > > > > diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c > > > index fb9f72813067..a92d5d7b7a92 100644 > > > --- a/drivers/cxl/acpi.c > > > +++ b/drivers/cxl/acpi.c > > > @@ -9,6 +9,8 @@ > > > #include "cxlpci.h" > > > #include "cxl.h" > > > > > > +#define CXL_RCRB_SIZE SZ_8K > > > + > > > static unsigned long cfmws_to_decoder_flags(int restrictions) > > > { > > > unsigned long flags = CXL_DECODER_F_ENABLE; > > > @@ -229,27 +231,82 @@ static int add_host_bridge_uport(struct device *match, void *arg) > > > struct cxl_chbs_context { > > > struct device *dev; > > > unsigned long long uid; > > > - resource_size_t chbcr; > > > + struct acpi_cedt_chbs chbs; > > > }; > > > > > > -static int cxl_get_chbcr(union acpi_subtable_headers *header, void *arg, > > > - const unsigned long end) > > > +static int cxl_get_chbs(union acpi_subtable_headers *header, void *arg, > > > + const unsigned long end) > > > { > > > struct cxl_chbs_context *ctx = arg; > > > struct acpi_cedt_chbs *chbs; > > > > > > - if (ctx->chbcr) > > > + if (ctx->chbs.base) > > > return 0; > > > > > > chbs = (struct acpi_cedt_chbs *) header; > > > > > > if (ctx->uid != chbs->uid) > > > return 0; > > > - ctx->chbcr = chbs->base; > > > + ctx->chbs = *chbs; > > > > > > return 0; > > > } > > > > > > +static resource_size_t cxl_get_chbcr(struct cxl_chbs_context *ctx) > > > +{ > > > > The core logic of this looks good, but this wants to be shared with the > > upstream port component register discovery. > > > > Full disclosure I am reconciling these patches with an attempt that Dave > > Jiang made at this topic. Since your series hit the list first I will > > let it take the lead, but then fill it in with comments and learnings > > from Dave's effort. > > > > So in this case Dave moved this into the drivers/cxl/core/regs.c with a > > function signature like: > > > > enum cxl_rcrb { > > CXL_RCRB_DOWNSTREAM, > > CXL_RCRB_UPSTREAM, > > }; > > > > resource_size_t cxl_rcrb_to_component(struct device *dev, > > resource_size_t rcrb_base, int len, > > enum cxl_rcrb which); > > > > ...where @which alternates when called by cxl_acpi for the downstream > > case, or cxl_mem for the upstream case. > > Ok, I see where to go here. Could you point me to Dave's postings you > are referring to? I checked linux-cxl and could not find anything > related to RCRB or that changes regs.c.
He was in the middle of tidying them when you posted your series, but I think it would not hurt to push them to a git tree so you can grab the bits and pieces you want.
Dave?
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