scsi: ufs-qcom: add print suppressing debugfs mechanism

Provide a mechanism for the userspace to suppress specific
debug prints via debugfs. This is useful in order to avoid
cases where too much printing would cause watchdog timers
to expire.

Change-Id: I2500b7621b631e260d98595ed8cfe7d5a496dc10
Signed-off-by: Dov Levenglick <dovl@codeaurora.org>

drivers/scsi/ufs/Makefile

@@ -5,4 +5,4 @@ obj-$(CONFIG_SCSI_UFSHCD) += ufshcd.o ufs_quirks.o
 obj-$(CONFIG_SCSI_UFSHCD_PCI) += ufshcd-pci.o
 obj-$(CONFIG_SCSI_UFSHCD_PLATFORM) += ufshcd-pltfrm.o
 obj-$(CONFIG_SCSI_UFS_TEST) += ufs_test.o
-obj-$(CONFIG_DEBUG_FS) += debugfs.o
+obj-$(CONFIG_DEBUG_FS) += debugfs.o qcom-debugfs.o

drivers/scsi/ufs/debugfs.c

@@ -1,4 +1,4 @@
-/* Copyright (c) 2013-2014, The Linux Foundation. All rights reserved.
+/* Copyright (c) 2013-2015, The Linux Foundation. All rights reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 and
@@ -1065,6 +1065,9 @@ void ufsdbg_add_debugfs(struct ufs_hba *hba)
 
 	ufsdbg_setup_fault_injection(hba);
 
+	if (hba->vops && hba->vops->add_debugfs)
+		hba->vops->add_debugfs(hba, hba->debugfs_files.debugfs_root);
+
 	return;
 
 err:
@@ -1076,6 +1079,8 @@ err_no_root:
 
 void ufsdbg_remove_debugfs(struct ufs_hba *hba)
 {
+	if (hba->vops && hba->vops->remove_debugfs)
+		hba->vops->remove_debugfs(hba);
 	debugfs_remove_recursive(hba->debugfs_files.debugfs_root);
 	kfree(hba->ufs_stats.tag_stats);
 

drivers/scsi/ufs/qcom-debugfs.c

@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2015, Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/debugfs.h>
+#include <linux/scsi/ufs/ufs-qcom.h>
+#include "qcom-debugfs.h"
+
+static void ufs_qcom_dbg_remove_debugfs(struct ufs_qcom_host *host);
+
+static int ufs_qcom_dbg_print_en_read(void *data, u64 *attr_val)
+{
+	struct ufs_qcom_host *host = data;
+
+	if (!host)
+		return -EINVAL;
+
+	*attr_val = (u64)host->dbg_print_en;
+	return 0;
+}
+
+static int ufs_qcom_dbg_print_en_set(void *data, u64 attr_id)
+{
+	struct ufs_qcom_host *host = data;
+
+	if (!host)
+		return -EINVAL;
+
+	if (attr_id & ~UFS_QCOM_DBG_PRINT_ALL)
+		return -EINVAL;
+
+	host->dbg_print_en = (u32)attr_id;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(ufs_qcom_dbg_print_en_ops,
+			ufs_qcom_dbg_print_en_read,
+			ufs_qcom_dbg_print_en_set,
+			"%llu\n");
+
+
+void ufs_qcom_dbg_add_debugfs(struct ufs_hba *hba, struct dentry *root)
+{
+	struct ufs_qcom_host *host;
+
+	if (!hba || !hba->priv) {
+		pr_err("%s: NULL host, exiting\n", __func__);
+		return;
+	}
+
+	host = hba->priv;
+	host->debugfs_files.debugfs_root = debugfs_create_dir("qcom", root);
+	if (IS_ERR(host->debugfs_files.debugfs_root))
+		/* Don't complain -- debugfs just isn't enabled */
+		goto err_no_root;
+	if (!host->debugfs_files.debugfs_root) {
+		/*
+		 * Complain -- debugfs is enabled, but it failed to
+		 * create the directory
+		 */
+		dev_err(host->hba->dev,
+			"%s: NULL debugfs root directory, exiting", __func__);
+		goto err_no_root;
+	}
+
+	host->debugfs_files.dbg_print_en =
+		debugfs_create_file("dbg_print_en", S_IRUSR | S_IWUSR,
+				    host->debugfs_files.debugfs_root, host,
+				    &ufs_qcom_dbg_print_en_ops);
+	if (!host->debugfs_files.dbg_print_en) {
+		dev_err(host->hba->dev,
+			"%s: failed to create dbg_print_en debugfs entry\n",
+			__func__);
+		goto err;
+	}
+	return;
+
+err:
+	ufs_qcom_dbg_remove_debugfs(host);
+err_no_root:
+	dev_err(host->hba->dev, "%s: failed to initialize debugfs\n", __func__);
+}
+
+static void ufs_qcom_dbg_remove_debugfs(struct ufs_qcom_host *host)
+{
+	debugfs_remove_recursive(host->debugfs_files.debugfs_root);
+	host->debugfs_files.debugfs_root = NULL;
+}

drivers/scsi/ufs/qcom-debugfs.h

@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2015, Linux Foundation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef QCOM_DEBUGFS_H_
+#define QCOM_DEBUGFS_H_
+
+#include <linux/scsi/ufs/ufshcd.h>
+
+#ifdef CONFIG_DEBUG_FS
+void ufs_qcom_dbg_add_debugfs(struct ufs_hba *hba, struct dentry *root);
+#endif
+
+#endif /* End of Header */

drivers/scsi/ufs/ufs-qcom.c

@@ -34,6 +34,9 @@
 #include "ufs-qcom.h"
 #include "ufshci.h"
 #include "ufs-qcom-ice.h"
+#include "qcom-debugfs.h"
+
+#define DEFAULT_UFS_QCOM_DBG_PRINT_EN	UFS_QCOM_DBG_PRINT_REGS_EN
 
 static struct ufs_qcom_host *ufs_qcom_hosts[MAX_UFS_QCOM_HOSTS];
 
@@ -1268,6 +1271,8 @@ static int ufs_qcom_init(struct ufs_hba *hba)
 	if (hba->dev->id < MAX_UFS_QCOM_HOSTS)
 		ufs_qcom_hosts[hba->dev->id] = host;
 
+	host->dbg_print_en |= DEFAULT_UFS_QCOM_DBG_PRINT_EN;
+
 	goto out;
 
 out_disable_phy:
@@ -1371,6 +1376,10 @@ out:
 static void ufs_qcom_print_hw_debug_reg_all(struct ufs_hba *hba)
 {
 	u32 reg;
+	struct ufs_qcom_host *host = hba->priv;
+
+	if (!(host->dbg_print_en & UFS_QCOM_DBG_PRINT_REGS_EN))
+		return;
 
 	ufs_qcom_dump_regs(hba, UFS_UFS_DBG_RD_REG_OCSC, 44,
 			"UFS_UFS_DBG_RD_REG_OCSC ");
@@ -1406,8 +1415,8 @@ static void ufs_qcom_print_hw_debug_reg_all(struct ufs_hba *hba)
 
 static void ufs_qcom_dump_dbg_regs(struct ufs_hba *hba)
 {
-	ufs_qcom_dump_regs(hba, REG_UFS_SYS1CLK_1US, 5,
-			"REG_UFS_SYS1CLK_1US ");
+	ufs_qcom_dump_regs(hba, REG_UFS_SYS1CLK_1US, 16,
+			"HCI Vendor Specific Registers ");
 
 	ufs_qcom_print_hw_debug_reg_all(hba);
 }
@@ -1437,6 +1446,9 @@ const struct ufs_hba_variant_ops ufs_hba_qcom_vops = {
 	.crypto_engine_get_err	= ufs_qcom_crypto_engine_get_err,
 	.crypto_engine_reset_err = ufs_qcom_crypto_engine_reset_err,
 	.dbg_register_dump	= ufs_qcom_dump_dbg_regs,
+#ifdef CONFIG_DEBUG_FS
+	.add_debugfs		= ufs_qcom_dbg_add_debugfs,
+#endif
 };
 
 /**

include/linux/scsi/ufs/ufs-qcom.h

@@ -15,6 +15,7 @@
 #define UFS_QCOM_H_
 
 #include <linux/phy/phy.h>
+#include <linux/scsi/ufs/ufshcd.h>
 
 #define MAX_UFS_QCOM_HOSTS	1
 #define MAX_U32                 (~(u32)0)
@@ -120,6 +121,11 @@ struct ufs_qcom_phy_vreg {
 	bool enabled;
 };
 
+/* QCOM UFS debug print bit mask */
+#define UFS_QCOM_DBG_PRINT_REGS_EN	BIT(0)
+
+#define UFS_QCOM_DBG_PRINT_ALL	UFS_QCOM_DBG_PRINT_REGS_EN
+
 static inline void
 ufs_qcom_get_controller_revision(struct ufs_hba *hba,
 				 u8 *major, u16 *minor, u16 *step)
@@ -189,6 +195,13 @@ struct ufs_hw_version {
 	u8 major;
 };
 
+#ifdef CONFIG_DEBUG_FS
+struct qcom_debugfs_files {
+	struct dentry *debugfs_root;
+	struct dentry *dbg_print_en;
+};
+#endif
+
 struct ufs_qcom_host {
 	/*
 	 * Set this capability if host controller supports the QUniPro mode
@@ -213,6 +226,11 @@ struct ufs_qcom_host {
 	void __iomem *dev_ref_clk_ctrl_mmio;
 	bool is_dev_ref_clk_enabled;
 	struct ufs_hw_version hw_ver;
+#ifdef CONFIG_DEBUG_FS
+	struct qcom_debugfs_files debugfs_files;
+#endif
+	/* Bitmask for enabling debug prints */
+	u32 dbg_print_en;
 };
 
 #define ufs_qcom_is_link_off(hba) ufshcd_is_link_off(hba)

include/linux/scsi/ufs/ufshcd.h

@@ -312,6 +312,8 @@ struct ufs_pwr_mode_info {
  * @crypto_engine_reset_err: resets the saved error status of
  *                         the cryptographic engine
  * @dbg_register_dump: used to dump controller debug information
+ * @add_debugfs: used to add debugfs entries
+ * @remove_debugfs: used to remove debugfs entries
  */
 struct ufs_hba_variant_ops {
 	const char *name;
@@ -340,6 +342,10 @@ struct ufs_hba_variant_ops {
 	int	(*crypto_engine_get_err)(struct ufs_hba *);
 	void	(*crypto_engine_reset_err)(struct ufs_hba *);
 	void	(*dbg_register_dump)(struct ufs_hba *hba);
+#ifdef CONFIG_DEBUG_FS
+	void	(*add_debugfs)(struct ufs_hba *hba, struct dentry *root);
+	void	(*remove_debugfs)(struct ufs_hba *hba);
+#endif
 };
 
 /* clock gating state  */