cxl/hdm: Add emulation when HDM decoders are not committed

For the case where DVSEC range register(s) are active and HDM decoders are
not committed, use RR to provide emulation. A first pass is done to note
whether any decoders are committed. If there are no committed endpoint
decoders, then DVSEC ranges will be used for emulation.

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/167640369536.935665.611974113442400127.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index a49543f22dcac445ec26670247f0ee6318200e5e..39e02f28b6a6f7245ef69b53ce2ae7b056d0ce5c 100644 (file)
--- a/drivers/cxl/core/hdm.c
+++ b/drivers/cxl/core/hdm.c
@@ -730,6 +730,32 @@ static int cxl_setup_hdm_decoder_from_dvsec(struct cxl_port *port,
        return 0;
 }
 
+static bool should_emulate_decoders(struct cxl_port *port)
+{
+       struct cxl_hdm *cxlhdm = dev_get_drvdata(&port->dev);
+       void __iomem *hdm = cxlhdm->regs.hdm_decoder;
+       u32 ctrl;
+       int i;
+
+       if (!is_cxl_endpoint(cxlhdm->port))
+               return false;
+
+       if (!hdm)
+               return true;
+
+       /*
+        * If any decoders are committed already, there should not be any
+        * emulated DVSEC decoders.
+        */
+       for (i = 0; i < cxlhdm->decoder_count; i++) {
+               ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(i));
+               if (FIELD_GET(CXL_HDM_DECODER0_CTRL_COMMITTED, ctrl))
+                       return false;
+       }
+
+       return true;
+}
+
 static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
                            int *target_map, void __iomem *hdm, int which,
                            u64 *dpa_base, struct cxl_endpoint_dvsec_info *info)
@@ -745,6 +771,9 @@ static int init_hdm_decoder(struct cxl_port *port, struct cxl_decoder *cxld,
                unsigned char target_id[8];
        } target_list;
 
+       if (should_emulate_decoders(port))
+               return cxl_setup_hdm_decoder_from_dvsec(port, cxld, which, info);
+
        if (is_endpoint_decoder(&cxld->dev))
                cxled = to_cxl_endpoint_decoder(&cxld->dev);