scsi: ufs-qcom: add sys-fs entries for PM QoS control

Add sys-fs entries to allow user space control PM QoS
latency parameters and enable/disable PM QoS voting.

The entries are added under:
/sys/bus/platform/devices/624000.ufshc/624000.ufshc:ufs_variant/

pm_qos_enable:
write 0 to disable PM QoS, 1 to enable.
Example: "echo 1 > pm_qos_enable"

pm_qos_latency_us:
write the desired value for each cpu group, separated by a comma.
Example: "echo 10,20 > pm_qos_latency_us"

Change-Id: I9797a1e62c4867ab831b4f18cbb1e0ca9834247b
Signed-off-by: Gilad Broner <gbroner@codeaurora.org>
Signed-off-by: Krishna Konda <kkonda@codeaurora.org>
[venkatg@codeaurora.org: resolved trivial merge conflicts]
Signed-off-by: Venkat Gopalakrishnan <venkatg@codeaurora.org>

drivers/scsi/ufs/ufs-qcom.c

@@ -58,8 +58,6 @@ static int ufs_qcom_update_sec_cfg(struct ufs_hba *hba, bool restore_sec_cfg);
 static void ufs_qcom_get_default_testbus_cfg(struct ufs_qcom_host *host);
 static int ufs_qcom_set_dme_vs_core_clk_ctrl_clear_div(struct ufs_hba *hba,
 						       u32 clk_cycles);
-static int ufs_qcom_pm_qos_init(struct ufs_qcom_host *host);
-static void ufs_qcom_pm_qos_remove(struct ufs_qcom_host *host);
 static void ufs_qcom_pm_qos_suspend(struct ufs_qcom_host *host);
 
 static void ufs_qcom_dump_regs(struct ufs_hba *hba, int offset, int len,
@@ -1410,9 +1408,122 @@ static void ufs_qcom_pm_qos_unvote_work(struct work_struct *work)
 		group->latency_us, UFS_QCOM_PM_QOS_UNVOTE_TIMEOUT_US);
 }
 
+static ssize_t ufs_qcom_pm_qos_enable_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev->parent);
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", host->pm_qos.is_enabled);
+}
+
+static ssize_t ufs_qcom_pm_qos_enable_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev->parent);
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+	unsigned long value;
+	unsigned long flags;
+	bool enable;
+	int i;
+
+	if (kstrtoul(buf, 0, &value))
+		return -EINVAL;
+
+	enable = !!value;
+
+	/*
+	 * Must take the spinlock and save irqs before changing the enabled
+	 * flag in order to keep correctness of PM QoS release.
+	 */
+	spin_lock_irqsave(hba->host->host_lock, flags);
+	if (enable == host->pm_qos.is_enabled) {
+		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		return count;
+	}
+	host->pm_qos.is_enabled = enable;
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
+
+	if (!enable)
+		for (i = 0; i < host->pm_qos.num_groups; i++) {
+			cancel_work_sync(&host->pm_qos.groups[i].vote_work);
+			cancel_work_sync(&host->pm_qos.groups[i].unvote_work);
+			spin_lock_irqsave(hba->host->host_lock, flags);
+			host->pm_qos.groups[i].state = PM_QOS_UNVOTED;
+			host->pm_qos.groups[i].active_reqs = 0;
+			spin_unlock_irqrestore(hba->host->host_lock, flags);
+			pm_qos_update_request(&host->pm_qos.groups[i].req,
+				PM_QOS_DEFAULT_VALUE);
+		}
+
+	return count;
+}
+
+static ssize_t ufs_qcom_pm_qos_latency_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev->parent);
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+	int ret;
+	int i;
+	int offset = 0;
+
+	for (i = 0; i < host->pm_qos.num_groups; i++) {
+		ret = snprintf(&buf[offset], PAGE_SIZE,
+			"cpu group #%d(mask=0x%lx): %d\n", i,
+			host->pm_qos.groups[i].mask.bits[0],
+			host->pm_qos.groups[i].latency_us);
+		if (ret > 0)
+			offset += ret;
+		else
+			break;
+	}
+
+	return offset;
+}
+
+static ssize_t ufs_qcom_pm_qos_latency_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t count)
+{
+	struct ufs_hba *hba = dev_get_drvdata(dev->parent);
+	struct ufs_qcom_host *host = ufshcd_get_variant(hba);
+	unsigned long value;
+	unsigned long flags;
+	char *strbuf;
+	char *strbuf_copy;
+	char *token;
+	int i;
+	int ret;
+
+	/* reserve one byte for null termination */
+	strbuf = kmalloc(count + 1, GFP_KERNEL);
+	if (!strbuf)
+		return -ENOMEM;
+	strbuf_copy = strbuf;
+	strlcpy(strbuf, buf, count + 1);
+
+	for (i = 0; i < host->pm_qos.num_groups; i++) {
+		token = strsep(&strbuf, ",");
+		if (!token)
+			break;
+
+		ret = kstrtoul(token, 0, &value);
+		if (ret)
+			break;
+
+		spin_lock_irqsave(hba->host->host_lock, flags);
+		host->pm_qos.groups[i].latency_us = value;
+		spin_unlock_irqrestore(hba->host->host_lock, flags);
+	}
+
+	kfree(strbuf_copy);
+	return count;
+}
+
 static int ufs_qcom_pm_qos_init(struct ufs_qcom_host *host)
 {
 	struct device_node *node = host->hba->dev->of_node;
+	struct device_attribute *attr;
 	int ret = 0;
 	int num_groups;
 	int num_values;
@@ -1510,6 +1621,26 @@ static int ufs_qcom_pm_qos_init(struct ufs_qcom_host *host)
 		pm_qos_add_request(&host->pm_qos.groups[i].req,
 			PM_QOS_CPU_DMA_LATENCY, PM_QOS_DEFAULT_VALUE);
 
+	/* PM QoS latency sys-fs attribute */
+	attr = &host->pm_qos.latency_attr;
+	attr->show = ufs_qcom_pm_qos_latency_show;
+	attr->store = ufs_qcom_pm_qos_latency_store;
+	sysfs_attr_init(&attr->attr);
+	attr->attr.name = "pm_qos_latency_us";
+	attr->attr.mode = S_IRUGO | S_IWUSR;
+	if (device_create_file(host->hba->var->dev, attr))
+		dev_dbg(host->hba->dev, "Failed to create sysfs for pm_qos_latency_us\n");
+
+	/* PM QoS enable sys-fs attribute */
+	attr = &host->pm_qos.enable_attr;
+	attr->show = ufs_qcom_pm_qos_enable_show;
+	attr->store = ufs_qcom_pm_qos_enable_store;
+	sysfs_attr_init(&attr->attr);
+	attr->attr.name = "pm_qos_enable";
+	attr->attr.mode = S_IRUGO | S_IWUSR;
+	if (device_create_file(host->hba->var->dev, attr))
+		dev_dbg(host->hba->dev, "Failed to create sysfs for pm_qos enable\n");
+
 	host->pm_qos.is_enabled = true;
 
 	return 0;

drivers/scsi/ufs/ufs-qcom.h

@@ -283,6 +283,8 @@ struct ufs_qcom_pm_qos_cpu_group {
 /**
  * struct ufs_qcom_pm_qos - data related to PM QoS voting logic
  * @groups: PM QoS cpu group state array
+ * @enable_attr: sysfs attribute to enable/disable PM QoS voting logic
+ * @latency_attr: sysfs attribute to set latency value
  * @workq: single threaded workqueue to run PM QoS voting/unvoting
  * @num_clusters: number of clusters defined
  * @default_cpu: cpu to use for voting for request not specifying a cpu
@@ -290,6 +292,8 @@ struct ufs_qcom_pm_qos_cpu_group {
  */
 struct ufs_qcom_pm_qos {
 	struct ufs_qcom_pm_qos_cpu_group *groups;
+	struct device_attribute enable_attr;
+	struct device_attribute latency_attr;
 	struct workqueue_struct *workq;
 	int num_groups;
 	int default_cpu;

drivers/scsi/ufs/ufshcd.h

@@ -369,6 +369,7 @@ struct ufs_hba_pm_qos_variant_ops {
  * @name: variant name
  */
 struct ufs_hba_variant {
+	struct device				*dev;
 	const char				*name;
 	struct ufs_hba_variant_ops		*vops;
 	struct ufs_hba_crypto_variant_ops	*crypto_vops;