[Skiboot] [RFC PATCH 3/5] hdat: parse and export STOP levels

[Oliver O'Halloran]

ISAv3 added the STOP instruction to act as a front end to the various
power saving modes. The exact function of the stop instruction is
implementation dependent and the firmware must advertise which "stop
levels" are supported.

This patch adds the required HDAT parsing and exports the
"ibm,enabled-stop-levels" devicetree node for use inside of skiboot.

Signed-off-by: Oliver O'Halloran <oohall at gmail.com>
---
 hdata/spira.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/hdata/spira.c b/hdata/spira.c
index e4e6b2d5830c..ed918a376adf 100644
--- a/hdata/spira.c
+++ b/hdata/spira.c
@@ -1049,6 +1049,62 @@ static void hostservices_parse(void)
 	hservices_from_hdat(dt_blob, size);
 }
 
+static void add_stop_levels(void)
+{
+	struct spira_ntuple *t = &spira.ntuples.proc_chip;
+	struct HDIF_common_hdr *hdif;
+	u32 stop_levels = ~0;
+	bool valid = false;
+	int i;
+
+	if (proc_gen < proc_gen_p9)
+		return;
+
+	/*
+	 * OPAL only exports a single set of flags to indicate the supported
+	 * STOP modes while the HDAT descibes the support top levels *per chip*
+	 * We parse the list of chips to find a common set of STOP levels to
+	 * export.
+	 */
+	for_each_ntuple_idx(t, hdif, i, SPPCRD_HDIF_SIG) {
+		const struct sppcrd_chip_info *cinfo =
+			HDIF_get_idata(hdif, SPPCRD_IDATA_CHIP_INFO, NULL);
+		u32 ve, chip_levels;
+
+		if (!cinfo)
+			continue;
+
+		/*
+		 * If the HDAT is too old contain the support STOP level then
+		 * assume we have none.
+		 */
+		if (be16_to_cpu(hdif->version) < 0x20) {
+			stop_levels = 0;
+			break;
+		}
+
+		ve = be32_to_cpu(cinfo->verif_exist_flags) & CPU_ID_VERIFY_MASK;
+		ve >>= CPU_ID_VERIFY_SHIFT;
+		if (ve == CHIP_VERIFY_NOT_INSTALLED ||
+		    ve == CHIP_VERIFY_UNUSABLE)
+			continue;
+
+		chip_levels = be32_to_cpu(cinfo->stop_levels);
+
+		prlog(PR_INSANE, "CHIP[%x] supported STOP mask 0x%.8x\n",
+			be32_to_cpu(cinfo->proc_chip_id), chip_levels);
+
+		stop_levels &= chip_levels;
+		valid = true;
+	}
+
+	if (!valid)
+		stop_levels = 0;
+
+	dt_add_property_cells(dt_new_check(opal_node, "power-mgt"),
+		"ibm,enabled-stop-levels", stop_levels);
+}
+
 /*
  * Legacy SPIRA is being deprecated and we have new SPIRA-H/S structures.
  * But on older system (p7?) we will continue to get legacy SPIRA.
@@ -1151,6 +1207,8 @@ int parse_hdat(bool is_opal, uint32_t master_cpu)
 	/* Parse System Attention Indicator inforamtion */
 	slca_dt_add_sai_node();
 
+	add_stop_levels();
+
 	prlog(PR_INFO, "Parsing HDAT...done\n");
 
 	return 0;
-- 
2.5.5