[v4,6/7] cxl: Add emulation when HDM decoders are not committed

Commit Message

Dave Jiang Feb. 8, 2023, 7:21 p.m. UTC

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 <[e-mail]>
Signed-off-by: Dave Jiang <[e-mail]>
---

v4:
- Remove ->emulate_decoders (Dan)
- Removed previous patch to just delete in this patch. (Dan)
---
 drivers/cxl/core/hdm.c |   29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

Patch

diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c
index a49543f22dca..39e02f28b6a6 100644
--- 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);