path: root/nvmepatch3-V4.patch

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index b92a7f767bfc..a143c72c3d0d 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -56,6 +56,11 @@ EXPORT_SYMBOL_GPL(nvme_max_retries);
 static int nvme_char_major;
 module_param(nvme_char_major, int, 0);
 
+static unsigned long default_ps_max_latency_us = 25000;
+module_param(default_ps_max_latency_us, ulong, 0644);
+MODULE_PARM_DESC(ps_max_latency_us,
+		 "default max power saving latency; overridden per device in sysfs");
+
 static LIST_HEAD(nvme_ctrl_list);
 static DEFINE_SPINLOCK(dev_list_lock);
 
@@ -1205,6 +1210,98 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl,
 	blk_queue_write_cache(q, vwc, vwc);
 }
 
+static void nvme_configure_apst(struct nvme_ctrl *ctrl)
+{
+	/*
+	 * APST (Autonomous Power State Transition) lets us program a
+	 * table of power state transitions that the controller will
+	 * perform automatically.  We configure it with a simple
+	 * heuristic: we are willing to spend at most 2% of the time
+	 * transitioning between power states.  Therefore, when running
+	 * in any given state, we will enter the next lower-power
+	 * non-operational state after waiting 100 * (enlat + exlat)
+	 * microseconds, as long as that state's total latency is under
+	 * the requested maximum latency.
+	 *
+	 * We will not autonomously enter any non-operational state for
+	 * which the total latency exceeds ps_max_latency_us.  Users
+	 * can set ps_max_latency_us to zero to turn off APST.
+	 */
+
+	unsigned apste;
+	struct nvme_feat_auto_pst *table;
+	int ret;
+
+	if (!ctrl->apsta)
+		return;	/* APST isn't supported. */
+
+	if (ctrl->npss > 31) {
+		dev_warn(ctrl->device, "NPSS is invalid; not using APST\n");
+		return;
+	}
+
+	table = kzalloc(sizeof(*table), GFP_KERNEL);
+	if (!table)
+		return;
+
+	if (ctrl->ps_max_latency_us == 0) {
+		/* Turn off APST. */
+		apste = 0;
+	} else {
+		__le64 target = cpu_to_le64(0);
+		int state;
+
+		/*
+		 * Walk through all states from lowest- to highest-power.
+		 * According to the spec, lower-numbered states use more
+		 * power.  NPSS, despite the name, is the index of the
+		 * lowest-power state, not the number of states.
+		 */
+		for (state = (int)ctrl->npss; state >= 0; state--) {
+			u64 total_latency_us, transition_ms;
+
+			if (target)
+				table->entries[state] = target;
+
+			/*
+			 * Is this state a useful non-operational state for
+			 * higher-power states to autonomously transition to?
+			 */
+			if (!(ctrl->psd[state].flags & 2))
+				continue;  /* It's an operational state. */
+
+			total_latency_us =
+				(u64)cpu_to_le32(ctrl->psd[state].entry_lat) +
+				+ cpu_to_le32(ctrl->psd[state].exit_lat);
+			if (total_latency_us > ctrl->ps_max_latency_us)
+				continue;
+
+			/*
+			 * This state is good.  Use it as the APST idle
+			 * target for higher power states.
+			 */
+			transition_ms = total_latency_us + 19;
+			do_div(transition_ms, 20);
+			if (transition_ms >= (1 << 24))
+				transition_ms = (1 << 24);
+
+			target = cpu_to_le64((state << 3) |
+					     (transition_ms << 8));
+		}
+
+		apste = 1;
+	}
+
+	ret = nvme_set_features(ctrl, NVME_FEAT_AUTO_PST, apste,
+				table, sizeof(*table), NULL);
+	if (ret)
+		dev_err(ctrl->device, "failed to set APST feature (%d)\n", ret);
+
+	kfree(table);
+}
+
+static struct attribute_group nvme_dev_dynamic_attrs_group;
+
 /*
  * Initialize the cached copies of the Identify data and various controller
  * register in our nvme_ctrl structure.  This should be called as soon as
@@ -1271,6 +1368,10 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 	ctrl->sgls = le32_to_cpu(id->sgls);
 	ctrl->kas = le16_to_cpu(id->kas);
 
+	ctrl->npss = id->npss;
+	ctrl->apsta = id->apsta;
+	memcpy(ctrl->psd, id->psd, sizeof(ctrl->psd));
+
 	if (ctrl->ops->is_fabrics) {
 		ctrl->icdoff = le16_to_cpu(id->icdoff);
 		ctrl->ioccsz = le32_to_cpu(id->ioccsz);
@@ -1294,6 +1395,10 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 	}
 
 	kfree(id);
+
+	nvme_configure_apst(ctrl);
+
+	sysfs_update_group(&ctrl->device->kobj, &nvme_dev_dynamic_attrs_group);
 	return ret;
 }
 EXPORT_SYMBOL_GPL(nvme_init_identify);
@@ -1564,6 +1669,41 @@ static ssize_t nvme_sysfs_show_address(struct device *dev,
 }
 static DEVICE_ATTR(address, S_IRUGO, nvme_sysfs_show_address, NULL);
 
+static ssize_t nvme_sysfs_show_ps_max_latency_us(
+	struct device *dev,
+	struct device_attribute *attr,
+	char *buf)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%llu\n", ctrl->ps_max_latency_us);
+}
+
+static ssize_t nvme_sysfs_store_ps_max_latency_us(
+	struct device *dev,
+	struct device_attribute *attr,
+	const char *buf, size_t size)
+{
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+	int ret;
+	u64 val;
+
+	ret = kstrtoull(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	if (ctrl->ps_max_latency_us != val) {
+		ctrl->ps_max_latency_us = val;
+		nvme_configure_apst(ctrl);
+	}
+
+	return size;
+}
+
+static DEVICE_ATTR(ps_max_latency_us, 0644,
+		   nvme_sysfs_show_ps_max_latency_us,
+		   nvme_sysfs_store_ps_max_latency_us);
+
 static struct attribute *nvme_dev_attrs[] = {
 	&dev_attr_reset_controller.attr,
 	&dev_attr_rescan_controller.attr,
@@ -1605,8 +1745,33 @@ static struct attribute_group nvme_dev_attrs_group = {
 	.is_visible	= nvme_dev_attrs_are_visible,
 };
 
+static struct attribute *nvme_dev_dynamic_attrs[] = {
+	&dev_attr_ps_max_latency_us.attr,
+	NULL
+};
+
+static umode_t nvme_dev_dynamic_attrs_are_visible(struct kobject *kobj,
+		struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct nvme_ctrl *ctrl = dev_get_drvdata(dev);
+
+	if (a == &dev_attr_ps_max_latency_us.attr) {
+		if (!ctrl->apsta)
+			return 0;
+	}
+
+	return a->mode;
+}
+
+static struct attribute_group nvme_dev_dynamic_attrs_group = {
+	.attrs		= nvme_dev_dynamic_attrs,
+	.is_visible	= nvme_dev_dynamic_attrs_are_visible,
+};
+
 static const struct attribute_group *nvme_dev_attr_groups[] = {
 	&nvme_dev_attrs_group,
+	&nvme_dev_dynamic_attrs_group,
 	NULL,
 };
 
@@ -1991,6 +2156,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev,
 	ctrl->quirks = quirks;
 	INIT_WORK(&ctrl->scan_work, nvme_scan_work);
 	INIT_WORK(&ctrl->async_event_work, nvme_async_event_work);
+	ctrl->ps_max_latency_us = default_ps_max_latency_us;
 
 	ret = nvme_set_instance(ctrl);
 	if (ret)
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index c2151761ec5f..16d51006afc0 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -129,13 +129,19 @@ struct nvme_ctrl {
 	u32 vs;
 	u32 sgls;
 	u16 kas;
+	u8 npss;
+	u8 apsta;
 	unsigned int kato;
 	bool subsystem;
 	unsigned long quirks;
+	struct nvme_id_power_state psd[32];
 	struct work_struct scan_work;
 	struct work_struct async_event_work;
 	struct delayed_work ka_work;
 
+	/* Power saving configuration */
+	u64 ps_max_latency_us;
+
 	/* Fabrics only */
 	u16 sqsize;
 	u32 ioccsz;
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index d8b37bab2887..a76237dac4b0 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -543,6 +543,12 @@ struct nvme_dsm_range {
 	__le64			slba;
 };
 
+/* Features */
+
+struct nvme_feat_auto_pst {
+	__le64 entries[32];
+};
+
 /* Admin commands */
 
 enum nvme_admin_opcode {
-- 
2.7.4