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From:   Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
To:     linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Cc:     huntbag@linux.vnet.ibm.com, npiggin@gmail.com,
        benh@kernel.crashing.org, mpe@ellerman.id.au,
        ego@linux.vnet.ibm.com,
        Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
Subject: [RFC PATCH v2 1/3] cpuidle/powernv: Add support for states with ibm,cpuidle-state-v1
Date:   Thu, 11 Oct 2018 18:52:35 +0530
In-Reply-To: <20181011132237.14604-1-akshay.adiga@linux.vnet.ibm.com>
References: <20181011132237.14604-1-akshay.adiga@linux.vnet.ibm.com>
Message-Id: <20181011132237.14604-2-akshay.adiga@linux.vnet.ibm.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

This patch adds support for new device-tree format for idle state
description.

Previously if a older kernel runs on a newer firmware, it may enable
all available states irrespective of its capability of handling it.
New device tree format adds a compatible flag, so that only kernel
which has the capability to handle the version of stop state will enable
it.

Older kernel will still see stop0 and stop0_lite in older format and we
will depricate it after some time.

1) Idea is to bump up the version in firmware if we find a bug or
regression in stop states. A fix will be provided in linux which would
now know about the bumped up version of stop states, where as kernel
without fixes would ignore the states.

2) Slowly deprecate cpuidle /cpuhotplug threshold which is hard-coded
into cpuidle-powernv driver. Instead use compatible strings to indicate
if idle state is suitable for cpuidle and hotplug.

New idle state device tree format :
       power-mgt {
            ...
         ibm,enabled-stop-levels = <0xec000000>;
         ibm,cpu-idle-state-psscr-mask = <0x0 0x3003ff 0x0 0x3003ff>;
         ibm,cpu-idle-state-latencies-ns = <0x3e8 0x7d0>;
         ibm,cpu-idle-state-psscr = <0x0 0x330 0x0 0x300330>;
         ibm,cpu-idle-state-flags = <0x100000 0x101000>;
         ibm,cpu-idle-state-residency-ns = <0x2710 0x4e20>;
         ibm,idle-states {
                     stop4 {
                         flags = <0x207000>;
                         compatible = "ibm,state-v1",
                                      "opal-supported";
                         type = "cpuidle";
                         psscr-mask = <0x0 0x3003ff>;
                         handle = <0x102>;
                         latency-ns = <0x186a0>;
                         residency-ns = <0x989680>;
                         psscr = <0x0 0x300374>;
                  };
                    ...
                    stop11 {
                     ...
                         compatible = "ibm,state-v1",
                                      "opal-supported";
                         type = "cpuoffline";
                         ...
                  };
             };
type strings :
"cpuidle" : indicates it should be used by cpuidle-driver
"cpuoffline" : indicates it should be used by hotplug driver

compatible strings :
"ibm,state-v1" : kernel checks if it knows about this version
"opal-supported" : indicates kernel can fall back to use opal
		   for stop-transitions

Signed-off-by: Akshay Adiga <akshay.adiga@linux.vnet.ibm.com>
---

Changes from v1 :
 - Code is rebased on Nick Piggin's v4 patch "powerpc/64s: reimplement book3s
   idle code in C"
 - Moved "cpuidle" and "cpuoffline" as seperate property called
   "type"
 

 arch/powerpc/include/asm/cpuidle.h    |   9 ++
 arch/powerpc/platforms/powernv/idle.c | 132 +++++++++++++++++++++++++-
 drivers/cpuidle/cpuidle-powernv.c     |  31 ++++--
 3 files changed, 160 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/include/asm/cpuidle.h b/arch/powerpc/include/asm/cpuidle.h
index 9844b3ded187..e920a15e797f 100644
--- a/arch/powerpc/include/asm/cpuidle.h
+++ b/arch/powerpc/include/asm/cpuidle.h
@@ -70,14 +70,23 @@
 
 #ifndef __ASSEMBLY__
 
+enum idle_state_type_t {
+	CPUIDLE_TYPE,
+	CPUOFFLINE_TYPE
+};
+
+#define POWERNV_THRESHOLD_LATENCY_NS 200000
+#define PNV_VER_NAME_LEN    32
 #define PNV_IDLE_NAME_LEN    16
 struct pnv_idle_states_t {
 	char name[PNV_IDLE_NAME_LEN];
+	char version[PNV_VER_NAME_LEN];
 	u32 latency_ns;
 	u32 residency_ns;
 	u64 psscr_val;
 	u64 psscr_mask;
 	u32 flags;
+	enum idle_state_type_t type;
 	bool valid;
 };
 
diff --git a/arch/powerpc/platforms/powernv/idle.c b/arch/powerpc/platforms/powernv/idle.c
index 96186af9e953..755918402591 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -54,6 +54,20 @@ static bool default_stop_found;
 static u64 pnv_first_tb_loss_level = MAX_STOP_STATE + 1;
 static u64 pnv_first_hv_loss_level = MAX_STOP_STATE + 1;
 
+
+static int parse_dt_v1(struct device_node *np);
+struct stop_version_t {
+	const char name[PNV_VER_NAME_LEN];
+	int (*parser_fn)(struct device_node *np);
+};
+struct stop_version_t known_versions[] = {
+		{
+			.name =  "ibm,state-v1",
+			.parser_fn = parse_dt_v1,
+		}
+	};
+const int nr_known_versions = 1;
+
 /*
  * psscr value and mask of the deepest stop idle state.
  * Used when a cpu is offlined.
@@ -1195,6 +1209,77 @@ static void __init pnv_probe_idle_states(void)
 		supported_cpuidle_states |= pnv_idle_states[i].flags;
 }
 
+static int parse_dt_v1(struct device_node *dt_node)
+{
+	const char *temp_str;
+	int rc;
+	int i = nr_pnv_idle_states;
+
+	if (!dt_node) {
+		pr_err("Invalid device_node\n");
+		return -EINVAL;
+	}
+
+	rc = of_property_read_string(dt_node, "name", &temp_str);
+	if (rc) {
+		pr_err("error reading names rc= %d\n", rc);
+		return -EINVAL;
+	}
+	strncpy(pnv_idle_states[i].name, temp_str, PNV_IDLE_NAME_LEN);
+	rc = of_property_read_u32(dt_node, "residency-ns",
+				  &pnv_idle_states[i].residency_ns);
+	if (rc) {
+		pr_err("error reading residency rc= %d\n", rc);
+		return -EINVAL;
+	}
+	rc = of_property_read_u32(dt_node, "latency-ns",
+				  &pnv_idle_states[i].latency_ns);
+	if (rc) {
+		pr_err("error reading latency rc= %d\n", rc);
+		return -EINVAL;
+	}
+	rc = of_property_read_u32(dt_node, "flags",
+				  &pnv_idle_states[i].flags);
+	if (rc) {
+		pr_err("error reading flags rc= %d\n", rc);
+		return -EINVAL;
+	}
+
+	/* We are not expecting power8 device-tree in this format */
+	rc = of_property_read_u64(dt_node, "psscr-mask",
+				  &pnv_idle_states[i].psscr_mask);
+	if (rc) {
+		pr_err("error reading psscr-mask rc= %d\n", rc);
+		return -EINVAL;
+	}
+	rc = of_property_read_u64(dt_node, "psscr",
+				  &pnv_idle_states[i].psscr_val);
+	if (rc) {
+		pr_err("error reading psscr rc= %d\n", rc);
+		return -EINVAL;
+	}
+
+	/*
+	 * TODO : save the version strings in data structure
+	 */
+	rc = of_property_read_string(dt_node, "type", &temp_str);
+	pr_info("type = %s\n", temp_str);
+	if (rc) {
+		pr_err("error reading type rc= %d\n", rc);
+		return -EINVAL;
+	}
+	if (strcmp(temp_str, "cpuidle") == 0)
+		pnv_idle_states[i].type = CPUIDLE_TYPE;
+	else if (strcmp(temp_str, "cpuoffline") == 0)
+		pnv_idle_states[i].type = CPUOFFLINE_TYPE;
+	else {
+		pr_err("Invalid type skipping %s\n",
+					pnv_idle_states[i].name);
+		return -EINVAL;
+	}
+	return 0;
+
+}
 /*
  * This function parses device-tree and populates all the information
  * into pnv_idle_states structure. It also sets up nr_pnv_idle_states
@@ -1203,8 +1288,9 @@ static void __init pnv_probe_idle_states(void)
 
 static int pnv_parse_cpuidle_dt(void)
 {
-	struct device_node *np;
+	struct device_node *np, *np1, *dt_node;
 	int nr_idle_states, i;
+	int additional_states = 0;
 	int rc = 0;
 	u32 *temp_u32;
 	u64 *temp_u64;
@@ -1218,8 +1304,14 @@ static int pnv_parse_cpuidle_dt(void)
 	nr_idle_states = of_property_count_u32_elems(np,
 						"ibm,cpu-idle-state-flags");
 
-	pnv_idle_states = kcalloc(nr_idle_states, sizeof(*pnv_idle_states),
-				  GFP_KERNEL);
+	np1 = of_find_node_by_path("/ibm,opal/power-mgt/ibm,idle-states");
+	if (np1) {
+		for_each_child_of_node(np1, dt_node)
+			additional_states++;
+	}
+	pr_info("states in new format : %d\n", additional_states);
+	pnv_idle_states = kcalloc(nr_idle_states + additional_states,
+				  sizeof(*pnv_idle_states), GFP_KERNEL);
 	temp_u32 = kcalloc(nr_idle_states, sizeof(u32),  GFP_KERNEL);
 	temp_u64 = kcalloc(nr_idle_states, sizeof(u64),  GFP_KERNEL);
 	temp_string = kcalloc(nr_idle_states, sizeof(char *),  GFP_KERNEL);
@@ -1298,8 +1390,40 @@ static int pnv_parse_cpuidle_dt(void)
 	for (i = 0; i < nr_idle_states; i++)
 		strlcpy(pnv_idle_states[i].name, temp_string[i],
 			PNV_IDLE_NAME_LEN);
+
+	/* Mark states as CPUIDLE_TYPE /CPUOFFLINE for older version*/
+	for (i = 0; i < nr_idle_states; i++) {
+		if (pnv_idle_states[i].latency_ns > POWERNV_THRESHOLD_LATENCY_NS)
+			pnv_idle_states[i].type  = CPUOFFLINE_TYPE;
+		else
+			pnv_idle_states[i].type  = CPUIDLE_TYPE;
+	}
 	nr_pnv_idle_states = nr_idle_states;
-	rc = 0;
+	/* Parsing node-based idle states device-tree format */
+	if (!np1) {
+		pr_info("dt does not contain ibm,idle_states");
+		goto out;
+	}
+	/* Parse each child node with appropriate parser_fn */
+	for_each_child_of_node(np1, dt_node) {
+		bool found_known_version = false;
+		/* we don't have state falling back to opal*/
+		for (i = 0; i < nr_known_versions ; i++) {
+			if (of_device_is_compatible(dt_node, known_versions[i].name)) {
+				rc = known_versions[i].parser_fn(dt_node);
+				if (rc) {
+					pr_err("%s could not parse\n", known_versions[i].name);
+					continue;
+				}
+				found_known_version = true;
+			}
+		}
+		if (!found_known_version) {
+			pr_info("Unsupported state, skipping all further state\n");
+			goto out;
+		}
+		nr_pnv_idle_states++;
+	}
 out:
 	kfree(temp_u32);
 	kfree(temp_u64);
diff --git a/drivers/cpuidle/cpuidle-powernv.c b/drivers/cpuidle/cpuidle-powernv.c
index 84b1ebe212b3..a15514ebd1c3 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -26,7 +26,6 @@
  * Expose only those Hardware idle states via the cpuidle framework
  * that have latency value below POWERNV_THRESHOLD_LATENCY_NS.
  */
-#define POWERNV_THRESHOLD_LATENCY_NS 200000
 
 static struct cpuidle_driver powernv_idle_driver = {
 	.name             = "powernv_idle",
@@ -265,7 +264,7 @@ extern u32 pnv_get_supported_cpuidle_states(void);
 static int powernv_add_idle_states(void)
 {
 	int nr_idle_states = 1; /* Snooze */
-	int dt_idle_states;
+	int dt_idle_states = 0;
 	u32 has_stop_states = 0;
 	int i;
 	u32 supported_flags = pnv_get_supported_cpuidle_states();
@@ -277,14 +276,19 @@ static int powernv_add_idle_states(void)
 		goto out;
 	}
 
-	/* TODO: Count only states which are eligible for cpuidle */
-	dt_idle_states = nr_pnv_idle_states;
+	/* Count only cpuidle states*/
+	for (i = 0; i < nr_pnv_idle_states; i++) {
+		if (pnv_idle_states[i].type == CPUIDLE_TYPE)
+			dt_idle_states++;
+	}
+	pr_info("idle states in dt = %d , states with idle flag = %d",
+					nr_pnv_idle_states, dt_idle_states);
 
 	/*
 	 * Since snooze is used as first idle state, max idle states allowed is
 	 * CPUIDLE_STATE_MAX -1
 	 */
-	if (nr_pnv_idle_states > CPUIDLE_STATE_MAX - 1) {
+	if (dt_idle_states > CPUIDLE_STATE_MAX - 1) {
 		pr_warn("cpuidle-powernv: discovered idle states more than allowed");
 		dt_idle_states = CPUIDLE_STATE_MAX - 1;
 	}
@@ -305,8 +309,15 @@ static int powernv_add_idle_states(void)
 		 * Skip the platform idle state whose flag isn't in
 		 * the supported_cpuidle_states flag mask.
 		 */
-		if ((state->flags & supported_flags) != state->flags)
+		if ((state->flags & supported_flags) != state->flags) {
+			pr_warn("State %d does not have supported flag\n", i);
+			continue;
+		}
+		if (state->type != CPUIDLE_TYPE) {
+			pr_info("State %d is not idletype, it of %d type\n", i,
+								state->type);
 			continue;
+		}
 		/*
 		 * If an idle state has exit latency beyond
 		 * POWERNV_THRESHOLD_LATENCY_NS then don't use it
@@ -321,8 +332,10 @@ static int powernv_add_idle_states(void)
 		exit_latency = DIV_ROUND_UP(state->latency_ns, 1000);
 		target_residency = DIV_ROUND_UP(state->residency_ns, 1000);
 
-		if (has_stop_states && !(state->valid))
+		if (has_stop_states && !(state->valid)) {
+			pr_warn("State %d is invalid\n", i);
 				continue;
+		}
 
 		if (state->flags & OPAL_PM_TIMEBASE_STOP)
 			stops_timebase = true;
@@ -360,8 +373,10 @@ static int powernv_add_idle_states(void)
 					  state->psscr_mask);
 		}
 #endif
-		else
+		else {
+			pr_warn("cpuidle-powernv : could not add state\n");
 			continue;
+		}
 		nr_idle_states++;
 	}
 out:
-- 
2.17.1