[PATCH 2/2] fpga: add FPGA manager debugfs

[Alan Tull <atull@kernel.org>]

From: Alan Tull <atull@opensource.altera.com>

Implement DebugFS for the FPGA Manager Framework for
debugging and developmental use.

Enabled by CONFIG_FPGA_MGR_DEBUG_FS

Each FPGA gets its own directory such as
 <debugfs>/fpga_manager/fpga0 and three files:

 * [RW] flags          = flags as defined in fpga-mgr.h
 * [RW] firmware_name  = write/read back name of FPGA image
                         firmware file to program
 * [WO] image          = write-only file for directly writing
                         fpga image w/o firmware layer
 * [RW] config_complete_timeout_us = maximum for the FPGA to
                         go to the operating state after
			 programming

The debugfs is implemented in a separate fpga_mgr_debugfs.c
file, but the FPGA manager core is still built as one
module.  Note the name change from fpga-mgr.ko to fpga_mgr.ko.

Signed-off-by: Alan Tull <atull@kernel.org>
Signed-off-by: Matthew Gerlach <matthew.gerlach@linux.intel.com>
---
 drivers/fpga/Kconfig            |   7 ++
 drivers/fpga/Makefile           |   4 +-
 drivers/fpga/fpga-mgr-debugfs.c | 221 ++++++++++++++++++++++++++++++++++++++++
 drivers/fpga/fpga-mgr-debugfs.h |  22 ++++
 drivers/fpga/fpga-mgr.c         |   8 ++
 include/linux/fpga/fpga-mgr.h   |   3 +
 6 files changed, 264 insertions(+), 1 deletion(-)
 create mode 100644 drivers/fpga/fpga-mgr-debugfs.c
 create mode 100644 drivers/fpga/fpga-mgr-debugfs.h

diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
index 1ebcef4..600924d 100644
--- a/drivers/fpga/Kconfig
+++ b/drivers/fpga/Kconfig
@@ -9,6 +9,13 @@ menuconfig FPGA
 	  kernel.  The FPGA framework adds a FPGA manager class and FPGA
 	  manager drivers.
 
+config FPGA_MGR_DEBUG_FS
+       bool "FPGA Manager DebugFS"
+       depends on FPGA && DEBUG_FS
+       help
+         Say Y here if you want to expose a DebugFS interface for the
+	 FPGA Manager Framework.
+
 if FPGA
 
 config FPGA_MGR_SOCFPGA
diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
index 7a2d73b..62910cc 100644
--- a/drivers/fpga/Makefile
+++ b/drivers/fpga/Makefile
@@ -4,7 +4,9 @@
 #
 
 # Core FPGA Manager Framework
-obj-$(CONFIG_FPGA)			+= fpga-mgr.o
+obj-$(CONFIG_FPGA)			+= fpga_mgr.o
+fpga_mgr-y				:= fpga-mgr.o
+fpga_mgr-$(CONFIG_FPGA_MGR_DEBUG_FS)	+= fpga-mgr-debugfs.o
 
 # FPGA Manager Drivers
 obj-$(CONFIG_FPGA_MGR_ALTERA_CVP)	+= altera-cvp.o
diff --git a/drivers/fpga/fpga-mgr-debugfs.c b/drivers/fpga/fpga-mgr-debugfs.c
new file mode 100644
index 0000000..f2fdf58
--- /dev/null
+++ b/drivers/fpga/fpga-mgr-debugfs.c
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * FPGA Manager DebugFS
+ *
+ *  Copyright (C) 2016-2018 Intel Corporation.  All rights reserved.
+ */
+#include <linux/debugfs.h>
+#include <linux/fpga/fpga-mgr.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+static struct dentry *fpga_mgr_debugfs_root;
+
+struct fpga_mgr_debugfs {
+	struct dentry *debugfs_dir;
+	struct fpga_image_info *info;
+};
+
+static ssize_t fpga_mgr_firmware_write_file(struct file *file,
+					    const char __user *user_buf,
+					    size_t count, loff_t *ppos)
+{
+	struct fpga_manager *mgr = file->private_data;
+	struct fpga_mgr_debugfs *debugfs = mgr->debugfs;
+	struct device *dev = &mgr->dev;
+	char *buf;
+	int ret;
+
+	ret = fpga_mgr_lock(mgr);
+	if (ret) {
+		dev_err(dev, "FPGA manager is busy\n");
+		return -EBUSY;
+	}
+
+	buf = devm_kzalloc(dev, count, GFP_KERNEL);
+	if (!buf) {
+		fpga_mgr_unlock(mgr);
+		return -ENOMEM;
+	}
+
+	if (copy_from_user(buf, user_buf, count)) {
+		fpga_mgr_unlock(mgr);
+		devm_kfree(dev, buf);
+		return -EFAULT;
+	}
+
+	buf[count] = 0;
+	if (buf[count - 1] == '\n')
+		buf[count - 1] = 0;
+
+	/* Release previous firmware name (if any). Save current one. */
+	if (debugfs->info->firmware_name)
+		devm_kfree(dev, debugfs->info->firmware_name);
+	debugfs->info->firmware_name = buf;
+
+	ret = fpga_mgr_load(mgr, debugfs->info);
+	if (ret)
+		dev_err(dev, "fpga_mgr_load returned with value %d\n", ret);
+
+	fpga_mgr_unlock(mgr);
+
+	return count;
+}
+
+static ssize_t fpga_mgr_firmware_read_file(struct file *file,
+					   char __user *user_buf,
+					   size_t count, loff_t *ppos)
+{
+	struct fpga_manager *mgr = file->private_data;
+	struct fpga_mgr_debugfs *debugfs = mgr->debugfs;
+	char *buf;
+	int ret;
+
+	if (!debugfs->info->firmware_name)
+		return 0;
+
+	buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = snprintf(buf, PAGE_SIZE, "%s\n", debugfs->info->firmware_name);
+	if (ret < 0) {
+		kfree(buf);
+		return ret;
+	}
+
+	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
+	kfree(buf);
+
+	return ret;
+}
+
+static const struct file_operations fpga_mgr_firmware_fops = {
+	.open = simple_open,
+	.read = fpga_mgr_firmware_read_file,
+	.write = fpga_mgr_firmware_write_file,
+	.llseek = default_llseek,
+};
+
+static ssize_t fpga_mgr_image_write_file(struct file *file,
+					 const char __user *user_buf,
+					 size_t count, loff_t *ppos)
+{
+	struct fpga_manager *mgr = file->private_data;
+	struct fpga_mgr_debugfs *debugfs = mgr->debugfs;
+	struct device *dev = &mgr->dev;
+	char *buf;
+	int ret;
+
+	dev_info(dev, "writing %zu bytes to %s\n", count, mgr->name);
+
+	ret = fpga_mgr_lock(mgr);
+	if (ret) {
+		dev_err(dev, "FPGA manager is busy\n");
+		return -EBUSY;
+	}
+
+	buf = kzalloc(count, GFP_KERNEL);
+	if (!buf) {
+		fpga_mgr_unlock(mgr);
+		return -ENOMEM;
+	}
+
+	if (copy_from_user(buf, user_buf, count)) {
+		fpga_mgr_unlock(mgr);
+		kfree(buf);
+		return -EFAULT;
+	}
+
+	/* If firmware interface was previously used, forget it. */
+	if (debugfs->info->firmware_name)
+		devm_kfree(dev, debugfs->info->firmware_name);
+	debugfs->info->firmware_name = NULL;
+
+	debugfs->info->buf = buf;
+	debugfs->info->count = count;
+
+	ret = fpga_mgr_load(mgr, debugfs->info);
+	if (ret)
+		dev_err(dev, "fpga_mgr_load returned with value %d\n", ret);
+
+	fpga_mgr_unlock(mgr);
+
+	debugfs->info->buf = NULL;
+	debugfs->info->count = 0;
+
+	kfree(buf);
+
+	return count;
+}
+
+static const struct file_operations fpga_mgr_image_fops = {
+	.open = simple_open,
+	.write = fpga_mgr_image_write_file,
+	.llseek = default_llseek,
+};
+
+void fpga_mgr_debugfs_add(struct fpga_manager *mgr)
+{
+	struct device *dev = &mgr->dev;
+	struct fpga_mgr_debugfs *debugfs;
+	struct fpga_image_info *info;
+
+	if (!fpga_mgr_debugfs_root)
+		return;
+
+	debugfs = kzalloc(sizeof(*debugfs), GFP_KERNEL);
+	if (!debugfs)
+		return;
+
+	info = fpga_image_info_alloc(dev);
+	if (!info) {
+		kfree(debugfs);
+		return;
+	}
+	debugfs->info = info;
+
+	debugfs->debugfs_dir = debugfs_create_dir(dev_name(dev),
+						  fpga_mgr_debugfs_root);
+
+	debugfs_create_file("firmware_name", 0600, debugfs->debugfs_dir, mgr,
+			    &fpga_mgr_firmware_fops);
+
+	debugfs_create_file("image", 0200, debugfs->debugfs_dir, mgr,
+			    &fpga_mgr_image_fops);
+
+	debugfs_create_u32("flags", 0600, debugfs->debugfs_dir, &info->flags);
+
+	debugfs_create_u32("config_complete_timeout_us", 0600,
+			   debugfs->debugfs_dir,
+			   &info->config_complete_timeout_us);
+
+	mgr->debugfs = debugfs;
+}
+
+void fpga_mgr_debugfs_remove(struct fpga_manager *mgr)
+{
+	struct fpga_mgr_debugfs *debugfs = mgr->debugfs;
+
+	if (!fpga_mgr_debugfs_root)
+		return;
+
+	debugfs_remove_recursive(debugfs->debugfs_dir);
+
+	/* this function also frees debugfs->info->firmware_name */
+	fpga_image_info_free(debugfs->info);
+
+	kfree(debugfs);
+}
+
+void fpga_mgr_debugfs_init(void)
+{
+	fpga_mgr_debugfs_root = debugfs_create_dir("fpga_manager", NULL);
+	if (!fpga_mgr_debugfs_root)
+		pr_warn("fpga_mgr: Failed to create debugfs root\n");
+}
+
+void fpga_mgr_debugfs_uninit(void)
+{
+	debugfs_remove_recursive(fpga_mgr_debugfs_root);
+}
diff --git a/drivers/fpga/fpga-mgr-debugfs.h b/drivers/fpga/fpga-mgr-debugfs.h
new file mode 100644
index 0000000..17cd3eb
--- /dev/null
+++ b/drivers/fpga/fpga-mgr-debugfs.h
@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#ifndef _LINUX_FPGA_MGR_DEBUGFS_H
+#define _LINUX_FPGA_MGR_DEBUGFS_H
+
+#if IS_ENABLED(CONFIG_FPGA_MGR_DEBUG_FS)
+
+void fpga_mgr_debugfs_add(struct fpga_manager *mgr);
+void fpga_mgr_debugfs_remove(struct fpga_manager *mgr);
+void fpga_mgr_debugfs_init(void);
+void fpga_mgr_debugfs_uninit(void);
+
+#else
+
+void fpga_mgr_debugfs_add(struct fpga_manager *mgr) {}
+void fpga_mgr_debugfs_remove(struct fpga_manager *mgr) {}
+void fpga_mgr_debugfs_init(void) {}
+void fpga_mgr_debugfs_uninit(void) {}
+
+#endif /* CONFIG_FPGA_MGR_DEBUG_FS */
+
+#endif /*_LINUX_FPGA_MGR_DEBUGFS_H */
diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index c8684bc..66eb6f6 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -17,6 +17,7 @@
 #include <linux/slab.h>
 #include <linux/scatterlist.h>
 #include <linux/highmem.h>
+#include "fpga-mgr-debugfs.h"
 
 static DEFINE_IDA(fpga_mgr_ida);
 static struct class *fpga_mgr_class;
@@ -698,6 +699,8 @@ int fpga_mgr_register(struct fpga_manager *mgr)
 	if (ret)
 		goto error_device;
 
+	fpga_mgr_debugfs_add(mgr);
+
 	dev_info(&mgr->dev, "%s registered\n", mgr->name);
 
 	return 0;
@@ -722,6 +725,8 @@ void fpga_mgr_unregister(struct fpga_manager *mgr)
 {
 	dev_info(&mgr->dev, "%s %s\n", __func__, mgr->name);
 
+	fpga_mgr_debugfs_remove(mgr);
+
 	/*
 	 * If the low level driver provides a method for putting fpga into
 	 * a desired state upon unregister, do it.
@@ -748,11 +753,14 @@ static int __init fpga_mgr_class_init(void)
 	fpga_mgr_class->dev_groups = fpga_mgr_groups;
 	fpga_mgr_class->dev_release = fpga_mgr_dev_release;
 
+	fpga_mgr_debugfs_init();
+
 	return 0;
 }
 
 static void __exit fpga_mgr_class_exit(void)
 {
+	fpga_mgr_debugfs_uninit();
 	class_destroy(fpga_mgr_class);
 	ida_destroy(&fpga_mgr_ida);
 }
diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
index 777c502..e8f2159 100644
--- a/include/linux/fpga/fpga-mgr.h
+++ b/include/linux/fpga/fpga-mgr.h
@@ -170,6 +170,9 @@ struct fpga_manager {
 	struct fpga_compat_id *compat_id;
 	const struct fpga_manager_ops *mops;
 	void *priv;
+#if IS_ENABLED(CONFIG_FPGA_MGR_DEBUG_FS)
+	void *debugfs;
+#endif
 };
 
 #define to_fpga_manager(d) container_of(d, struct fpga_manager, dev)
-- 
2.7.4