Add cxl_decoder_recommit() to restore one HDM decoder that the driver holds as committed but hardware no longer reports Committed, rewriting the cached settings and committing it again.
Restoring the decoders below a reset Port means reprogramming each one along the path to every affected endpoint. cxl_decoder_recommit() does that for a single decoder, so it will be reused later for the full path. Signed-off-by: Fabio M. De Francesco <[email protected]> --- drivers/cxl/core/core.h | 1 + drivers/cxl/core/hdm.c | 71 +++++++++++++++++++++++++++++++++++++++++ 2 files changed, 72 insertions(+) diff --git a/drivers/cxl/core/core.h b/drivers/cxl/core/core.h index 4dc324f019ab..6d536fe7b446 100644 --- a/drivers/cxl/core/core.h +++ b/drivers/cxl/core/core.h @@ -215,6 +215,7 @@ int cxl_hdm_decode_init(struct cxl_dev_state *cxlds, struct cxl_hdm *cxlhdm, struct cxl_endpoint_dvsec_info *info); void cxl_enable_hdm(struct cxl_hdm *cxlhdm, u32 global_ctrl); int cxl_set_mem_enable(struct cxl_dev_state *cxlds, u16 val); +int cxl_decoder_recommit(struct cxl_decoder *cxld, u32 ctrl); int cxl_port_get_possible_dports(struct cxl_port *port); #ifdef CONFIG_CXL_FEATURES diff --git a/drivers/cxl/core/hdm.c b/drivers/cxl/core/hdm.c index 0c80b76a5f9b..d55d764895f8 100644 --- a/drivers/cxl/core/hdm.c +++ b/drivers/cxl/core/hdm.c @@ -849,6 +849,77 @@ static int cxl_decoder_commit(struct cxl_decoder *cxld) return 0; } +/** + * cxl_decoder_recommit - reprogram @cxld's HDM decoder registers and commit + * @cxld: decoder to reprogram from its cached settings + * @ctrl: CXL HDM Decoder n Control value to restore under the cached settings + * + * A reset of an upstream link clears the HDM decoder registers of every + * component below it, dropping Committed while the driver still holds the + * settings that were in effect. Restore those settings and commit. + * + * setup_hw_decoder() rewrites only Interleave Granularity, Interleave Ways and + * Target Range Type, so the rest of the control register would come from a read + * of the reset defaults. Per CXL r4.0 sec 8.2.4.20.7 Table 8-123 that register + * also holds BI, UIO, Upstream Interleave Granularity, Upstream Interleave Ways + * and Lock On Commit, none of which the driver models, and sec 8.2.4.20.12 makes + * device operation undefined if a device that requires BI is committed without + * it. Write @ctrl first so those fields are in place, with Commit masked off + * until setup_hw_decoder() has written the range. + * + * A decoder that hardware still reports Committed kept its programming across + * the reset and needs no work. A decoder with no ->commit is driven through the + * DVSEC ranges or is a passthrough decoder, and has no registers to program. + * + * Section 8.2.4.20.13 requires the traffic targeting @cxld to be quiesced while + * it is reprogrammed, which the caller owns. @cxld decodes nothing until the + * commit completes. + * + * Return: 0 on success or if @cxld needs no reprogramming, negative errno if the + * commit times out or if the hardware reports a commit error. + */ +int cxl_decoder_recommit(struct cxl_decoder *cxld, u32 ctrl) +{ + struct cxl_port *port = to_cxl_port(cxld->dev.parent); + struct cxl_hdm *cxlhdm = dev_get_drvdata(&port->dev); + void __iomem *hdm = cxlhdm->regs.hdm_decoder; + u32 hw_ctrl; + int rc; + + if ((cxld->flags & CXL_DECODER_F_ENABLE) == 0) + return 0; + + if (!cxld->commit) + return 0; + + hw_ctrl = readl(hdm + CXL_HDM_DECODER0_CTRL_OFFSET(cxld->id)); + if (FIELD_GET(CXL_HDM_DECODER0_CTRL_COMMITTED, hw_ctrl)) { + dev_dbg(&cxld->dev, "%s: still committed, no reprogram needed\n", + __func__); + return 0; + } + + writel(ctrl & ~(CXL_HDM_DECODER0_CTRL_COMMIT | + CXL_HDM_DECODER0_CTRL_COMMITTED | + CXL_HDM_DECODER0_CTRL_COMMIT_ERROR), + hdm + CXL_HDM_DECODER0_CTRL_OFFSET(cxld->id)); + + scoped_guard(rwsem_read, &cxl_rwsem.dpa) + setup_hw_decoder(cxld, hdm); + + rc = cxld_await_commit(hdm, cxld->id); + if (rc) { + dev_warn(&cxld->dev, "%s: failed to commit decoder: %d\n", + __func__, rc); + return rc; + } + + dev_dbg(&cxld->dev, "%s: reprogrammed HPA %#llx-%#llx\n", + __func__, cxld->hpa_range.start, cxld->hpa_range.end); + + return 0; +} + static int commit_reap(struct device *dev, void *data) { struct cxl_port *port = to_cxl_port(dev->parent); -- 2.55.0
