[PATCH v4 02/18] fpga: mgr: API change to replace fpga load functions with single function

[Alan Tull <atull@kernel.org>]

fpga-mgr has three methods for programming FPGAs, depending on
whether the image is in a scatter gather list, a contiguous
buffer, or a firmware file. This makes it difficult to write
upper layers as the caller has to assume whether the FPGA image
is in a sg table, as a single buffer, or a firmware file.
This commit moves these parameters to struct fpga_image_info
and adds a single function for programming fpgas.

New functions:
* fpga_mgr_load - given fpga manager and struct fpga_image_info,
   program the fpga.

* fpga_image_info_alloc - alloc a struct fpga_image_info.

* fpga_image_info_free - free a struct fpga_image_info.

These three functions are unexported:
* fpga_mgr_buf_load_sg
* fpga_mgr_buf_load
* fpga_mgr_firmware_load

Also use devm_kstrdup to copy firmware_name so we aren't making
assumptions about where it comes from when allocing/freeing the
struct fpga_image_info.

API documentation has been updated and a new document for
FPGA region has been added.

Signed-off-by: Alan Tull <atull@kernel.org>
---
v2: add fpga_image_info_alloc/free
    update copyright and author email
v3: fix bisectibility
v4: fix return value of fpga_image_info_alloc()
    save device in struct fpga_image_info
    remove device param from fpga_image_info_free()
    squash in the documentation patch minus stuff about locking
    which is included in the next patch
---
 Documentation/fpga/fpga-mgr.txt    | 119 ++++++++++++++++---------------------
 Documentation/fpga/fpga-region.txt |  95 +++++++++++++++++++++++++++++
 Documentation/fpga/overview.txt    |  23 +++++++
 drivers/fpga/fpga-mgr.c            |  68 +++++++++++++++++----
 drivers/fpga/fpga-region.c         |  43 +++++++++-----
 include/linux/fpga/fpga-mgr.h      |  24 +++++---
 6 files changed, 270 insertions(+), 102 deletions(-)
 create mode 100644 Documentation/fpga/fpga-region.txt
 create mode 100644 Documentation/fpga/overview.txt

diff --git a/Documentation/fpga/fpga-mgr.txt b/Documentation/fpga/fpga-mgr.txt
index 78f197f..6ebc714 100644
--- a/Documentation/fpga/fpga-mgr.txt
+++ b/Documentation/fpga/fpga-mgr.txt
@@ -11,61 +11,53 @@ hidden away in a low level driver which registers a set of ops with the core.
 The FPGA image data itself is very manufacturer specific, but for our purposes
 it's just binary data.  The FPGA manager core won't parse it.
 
+The FPGA image to be programmed can be in a scatter gather list, a single
+contiguous buffer, or a firmware file.  Because allocating contiguous kernel
+memory for the buffer should be avoided, users are encouraged to use a scatter
+gather list instead if possible.
+
+The particulars for programming the image are presented in a structure (struct
+fpga_image_info).  This struct contains parameters such as pointers to the
+FPGA image as well as image-specific particulars such as whether the image was
+built for full or partial reconfiguration.
 
 API Functions:
 ==============
 
-To program the FPGA from a file or from a buffer:
--------------------------------------------------
-
-	int fpga_mgr_buf_load(struct fpga_manager *mgr,
-			      struct fpga_image_info *info,
-		              const char *buf, size_t count);
-
-Load the FPGA from an image which exists as a contiguous buffer in
-memory. Allocating contiguous kernel memory for the buffer should be avoided,
-users are encouraged to use the _sg interface instead of this.
-
-        int fpga_mgr_buf_load_sg(struct fpga_manager *mgr,
-				 struct fpga_image_info *info,
-				 struct sg_table *sgt);
+To program the FPGA:
+--------------------
 
-Load the FPGA from an image from non-contiguous in memory. Callers can
-construct a sg_table using alloc_page backed memory.
+	int fpga_mgr_load(struct fpga_manager *mgr,
+			  struct fpga_image_info *info);
 
-	int fpga_mgr_firmware_load(struct fpga_manager *mgr,
-				   struct fpga_image_info *info,
-		                   const char *image_name);
-
-Load the FPGA from an image which exists as a file.  The image file must be on
-the firmware search path (see the firmware class documentation).  If successful,
+Load the FPGA from an image which is indicated in the info.  If successful,
 the FPGA ends up in operating mode.  Return 0 on success or a negative error
 code.
 
-A FPGA design contained in a FPGA image file will likely have particulars that
-affect how the image is programmed to the FPGA.  These are contained in struct
-fpga_image_info.  Currently the only such particular is a single flag bit
-indicating whether the image is for full or partial reconfiguration.
+To allocate or free a struct fpga_image_info:
+---------------------------------------------
+
+	struct fpga_image_info *fpga_image_info_alloc(struct device *dev);
+
+	void fpga_image_info_free(struct fpga_image_info *info);
 
 To get/put a reference to a FPGA manager:
 -----------------------------------------
 
 	struct fpga_manager *of_fpga_mgr_get(struct device_node *node);
 	struct fpga_manager *fpga_mgr_get(struct device *dev);
-
-Given a DT node or device, get an exclusive reference to a FPGA manager.
-
 	void fpga_mgr_put(struct fpga_manager *mgr);
 
-Release the reference.
+Given a DT node or device, get an exclusive reference to a FPGA manager.
+fpga_mgr_put releases the reference.
 
 
 To register or unregister the low level FPGA-specific driver:
 -------------------------------------------------------------
 
 	int fpga_mgr_register(struct device *dev, const char *name,
-		              const struct fpga_manager_ops *mops,
-		              void *priv);
+			      const struct fpga_manager_ops *mops,
+			      void *priv);
 
 	void fpga_mgr_unregister(struct device *dev);
 
@@ -78,59 +70,50 @@ How to write an image buffer to a supported FPGA
 /* Include to get the API */
 #include <linux/fpga/fpga-mgr.h>
 
-/* device node that specifies the FPGA manager to use */
-struct device_node *mgr_node = ...
-
-/* FPGA image is in this buffer.  count is size of the buffer. */
-char *buf = ...
-int count = ...
+struct fpga_manager *mgr;
+struct fpga_image_info *info;
+int ret;
 
 /* struct with information about the FPGA image to program. */
-struct fpga_image_info info;
+info = fpga_image_info_alloc(dev);
 
 /* flags indicates whether to do full or partial reconfiguration */
-info.flags = 0;
-
-int ret;
+info->flags = FPGA_MGR_PARTIAL_RECONFIG;
 
-/* Get exclusive control of FPGA manager */
-struct fpga_manager *mgr = of_fpga_mgr_get(mgr_node);
+/*
+ * At this point, indicate where the image is. This is pseudo-code; you're
+ * going to use one of these three.
+ */
+if (image is in a scatter gather table) {
 
-/* Load the buffer to the FPGA */
-ret = fpga_mgr_buf_load(mgr, &info, buf, count);
-
-/* Release the FPGA manager */
-fpga_mgr_put(mgr);
+	info->sgt = [your scatter gather table]
 
+} else if (image is in a buffer) {
 
-How to write an image file to a supported FPGA
-==============================================
-/* Include to get the API */
-#include <linux/fpga/fpga-mgr.h>
+	info->buf = [your image buffer]
+	info->count = [image buffer size]
 
-/* device node that specifies the FPGA manager to use */
-struct device_node *mgr_node = ...
+} else if (image is in a firmware file) {
 
-/* FPGA image is in this file which is in the firmware search path */
-const char *path = "fpga-image-9.rbf"
+	info->firmware_name = devm_kstrdup(dev, firmware_name, GFP_KERNEL);
 
-/* struct with information about the FPGA image to program. */
-struct fpga_image_info info;
-
-/* flags indicates whether to do full or partial reconfiguration */
-info.flags = 0;
-
-int ret;
+}
 
-/* Get exclusive control of FPGA manager */
-struct fpga_manager *mgr = of_fpga_mgr_get(mgr_node);
+/*
+ * Get a reference to FPGA manager.  This example uses the  device node of the
+ * manager.  You could use fpga_mgr_get() instead if you have the device instead
+ * of the device node.
+ */
+mgr = of_fpga_mgr_get(mgr_node);
 
-/* Get the firmware image (path) and load it to the FPGA */
-ret = fpga_mgr_firmware_load(mgr, &info, path);
+/* Load the buffer to the FPGA */
+ret = fpga_mgr_buf_load(mgr, &info, buf, count);
 
 /* Release the FPGA manager */
 fpga_mgr_put(mgr);
 
+/* Deallocate the image info if you're done with it */
+fpga_image_info_free(info);
 
 How to support a new FPGA device
 ================================
diff --git a/Documentation/fpga/fpga-region.txt b/Documentation/fpga/fpga-region.txt
new file mode 100644
index 0000000..139a02b
--- /dev/null
+++ b/Documentation/fpga/fpga-region.txt
@@ -0,0 +1,95 @@
+FPGA Regions
+
+Alan Tull 2017
+
+CONTENTS
+ - Introduction
+ - The FPGA region API
+ - Usage example
+
+Introduction
+============
+
+This document is meant to be an brief overview of the FPGA region API usage.  A
+more conceptual look at regions can be found in [1].
+
+For the purposes of this API document, let's just say that a region associates
+an FPGA Manager and a bridge (or bridges) with a reprogrammable region of an
+FPGA or the whole FPGA.  The API provides a way to register a region and to
+program a region.
+
+Currently the only layer above fpga-region.c in the kernel is the Device Tree
+support (of-fpga-region.c) described in [1].  The DT support layer uses regions
+to program the FPGA and then DT to handle enumeration.  The common region code
+is intended to be used by other schemes that have other ways of accomplishing
+enumeration after programming.
+
+An fpga-region can be set up to know the following things:
+* which FPGA manager to use to do the programming
+* which bridges to disable before programming and enable afterwards.
+
+Additional info needed to program the FPGA image is passed in the struct
+fpga_image_info [2] including:
+* pointers to the image as either a scatter-gather buffer, a contiguous
+  buffer, or the name of firmware file
+* flags indicating specifics such as whether the image if for partial
+  reconfiguration.
+
+===================
+The FPGA region API
+===================
+
+To register or unregister a region:
+-----------------------------------
+
+	int fpga_region_register(struct device *dev,
+				 struct fpga_region *region);
+	int fpga_region_unregister(struct fpga_region *region);
+
+An example of usage can be seen in the probe function of [3]
+
+To program an FPGA:
+-------------------
+	int fpga_region_program_fpga(struct fpga_region *region);
+
+This function operates on info passed in the fpga_image_info
+(region->info).
+
+This function will attempt to:
+ * lock the region's mutex
+ * lock the region's FPGA manager
+ * build a list of FPGA bridges if a method has been specified to do so
+ * disable the bridges
+ * program the FPGA
+ * re-enable the bridges
+ * release the locks
+
+=============
+Usage example
+=============
+
+First, allocate the info struct:
+
+	info = fpga_image_info_alloc(dev);
+	if (!info)
+		return -ENOMEM;
+
+Set flags as needed, i.e.
+
+	info->flags |= FPGA_MGR_PARTIAL_RECONFIG;
+
+Point to your FPGA image, such as:
+
+	info->sgt = &sgt;
+
+Add info to region and do the programming:
+
+	region->info = info;
+	ret = fpga_region_program_fpga(region);
+
+Then enumerate whatever hardware has appeared in the FPGA.
+
+--
+[1] ../devicetree/bindings/fpga/fpga-region.txt
+[2] ./fpga-mgr.txt
+[3] ../../drivers/fpga/of-fpga-region.c
diff --git a/Documentation/fpga/overview.txt b/Documentation/fpga/overview.txt
new file mode 100644
index 0000000..0f1236e
--- /dev/null
+++ b/Documentation/fpga/overview.txt
@@ -0,0 +1,23 @@
+Linux kernel FPGA support
+
+Alan Tull 2017
+
+The main point of this project has been to separate the out the upper layers
+that know when to reprogram a FPGA from the lower layers that know how to
+reprogram a specific FPGA device.  The intention is to make this manufacturer
+agnostic, understanding that of course the FPGA images are very device specific
+themselves.
+
+The framework in the kernel includes:
+* low level FPGA manager drivers that know how to program a specific device
+* the fpga-mgr framework they are registered with
+* low level FPGA bridge drivers for hard/soft bridges which are intended to
+  be disable during FPGA programming
+* the fpga-bridge framework they are registered with
+* the fpga-region framework which associates and controls managers and bridges
+  as reconfigurable regions
+* the of-fpga-region support for reprogramming FPGAs when device tree overlays
+  are applied.
+
+I would encourage you the user to add code that creates FPGA regions rather
+that trying to control managers and bridges separately.
diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index 188ffef..a8dd549 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -2,6 +2,7 @@
  * FPGA Manager Core
  *
  *  Copyright (C) 2013-2015 Altera Corporation
+ *  Copyright (C) 2017 Intel Corporation
  *
  * With code from the mailing list:
  * Copyright (C) 2013 Xilinx, Inc.
@@ -31,6 +32,40 @@
 static DEFINE_IDA(fpga_mgr_ida);
 static struct class *fpga_mgr_class;
 
+struct fpga_image_info *fpga_image_info_alloc(struct device *dev)
+{
+	struct fpga_image_info *info;
+
+	get_device(dev);
+
+	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+	if (!info) {
+		put_device(dev);
+		return NULL;
+	}
+
+	info->dev = dev;
+
+	return info;
+}
+EXPORT_SYMBOL_GPL(fpga_image_info_alloc);
+
+void fpga_image_info_free(struct fpga_image_info *info)
+{
+	struct device *dev;
+
+	if (!info)
+		return;
+
+	dev = info->dev;
+	if (info->firmware_name)
+		devm_kfree(dev, info->firmware_name);
+
+	devm_kfree(dev, info);
+	put_device(dev);
+}
+EXPORT_SYMBOL_GPL(fpga_image_info_free);
+
 /*
  * Call the low level driver's write_init function.  This will do the
  * device-specific things to get the FPGA into the state where it is ready to
@@ -137,8 +172,9 @@ static int fpga_mgr_write_complete(struct fpga_manager *mgr,
  *
  * Return: 0 on success, negative error code otherwise.
  */
-int fpga_mgr_buf_load_sg(struct fpga_manager *mgr, struct fpga_image_info *info,
-			 struct sg_table *sgt)
+static int fpga_mgr_buf_load_sg(struct fpga_manager *mgr,
+				struct fpga_image_info *info,
+				struct sg_table *sgt)
 {
 	int ret;
 
@@ -170,7 +206,6 @@ int fpga_mgr_buf_load_sg(struct fpga_manager *mgr, struct fpga_image_info *info,
 
 	return fpga_mgr_write_complete(mgr, info);
 }
-EXPORT_SYMBOL_GPL(fpga_mgr_buf_load_sg);
 
 static int fpga_mgr_buf_load_mapped(struct fpga_manager *mgr,
 				    struct fpga_image_info *info,
@@ -210,8 +245,9 @@ static int fpga_mgr_buf_load_mapped(struct fpga_manager *mgr,
  *
  * Return: 0 on success, negative error code otherwise.
  */
-int fpga_mgr_buf_load(struct fpga_manager *mgr, struct fpga_image_info *info,
-		      const char *buf, size_t count)
+static int fpga_mgr_buf_load(struct fpga_manager *mgr,
+			     struct fpga_image_info *info,
+			     const char *buf, size_t count)
 {
 	struct page **pages;
 	struct sg_table sgt;
@@ -266,7 +302,6 @@ int fpga_mgr_buf_load(struct fpga_manager *mgr, struct fpga_image_info *info,
 
 	return rc;
 }
-EXPORT_SYMBOL_GPL(fpga_mgr_buf_load);
 
 /**
  * fpga_mgr_firmware_load - request firmware and load to fpga
@@ -282,9 +317,9 @@ EXPORT_SYMBOL_GPL(fpga_mgr_buf_load);
  *
  * Return: 0 on success, negative error code otherwise.
  */
-int fpga_mgr_firmware_load(struct fpga_manager *mgr,
-			   struct fpga_image_info *info,
-			   const char *image_name)
+static int fpga_mgr_firmware_load(struct fpga_manager *mgr,
+				  struct fpga_image_info *info,
+				  const char *image_name)
 {
 	struct device *dev = &mgr->dev;
 	const struct firmware *fw;
@@ -307,7 +342,18 @@ int fpga_mgr_firmware_load(struct fpga_manager *mgr,
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(fpga_mgr_firmware_load);
+
+int fpga_mgr_load(struct fpga_manager *mgr, struct fpga_image_info *info)
+{
+	if (info->sgt)
+		return fpga_mgr_buf_load_sg(mgr, info, info->sgt);
+	if (info->buf && info->count)
+		return fpga_mgr_buf_load(mgr, info, info->buf, info->count);
+	if (info->firmware_name)
+		return fpga_mgr_firmware_load(mgr, info, info->firmware_name);
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(fpga_mgr_load);
 
 static const char * const state_str[] = {
 	[FPGA_MGR_STATE_UNKNOWN] =		"unknown",
@@ -578,7 +624,7 @@ static void __exit fpga_mgr_class_exit(void)
 	ida_destroy(&fpga_mgr_ida);
 }
 
-MODULE_AUTHOR("Alan Tull <atull@opensource.altera.com>");
+MODULE_AUTHOR("Alan Tull <atull@kernel.org>");
 MODULE_DESCRIPTION("FPGA manager framework");
 MODULE_LICENSE("GPL v2");
 
diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
index 91755562..120c496 100644
--- a/drivers/fpga/fpga-region.c
+++ b/drivers/fpga/fpga-region.c
@@ -226,14 +226,11 @@ static int fpga_region_get_bridges(struct fpga_region *region,
 /**
  * fpga_region_program_fpga - program FPGA
  * @region: FPGA region
- * @firmware_name: name of FPGA image firmware file
  * @overlay: device node of the overlay
- * Program an FPGA using information in the device tree.
- * Function assumes that there is a firmware-name property.
+ * Program an FPGA using information in the region's fpga image info.
  * Return 0 for success or negative error code.
  */
 static int fpga_region_program_fpga(struct fpga_region *region,
-				    const char *firmware_name,
 				    struct device_node *overlay)
 {
 	struct fpga_manager *mgr;
@@ -264,7 +261,7 @@ static int fpga_region_program_fpga(struct fpga_region *region,
 		goto err_put_br;
 	}
 
-	ret = fpga_mgr_firmware_load(mgr, region->info, firmware_name);
+	ret = fpga_mgr_load(mgr, region->info);
 	if (ret) {
 		pr_err("failed to load fpga image\n");
 		goto err_put_br;
@@ -357,16 +354,15 @@ static int child_regions_with_firmware(struct device_node *overlay)
 static int fpga_region_notify_pre_apply(struct fpga_region *region,
 					struct of_overlay_notify_data *nd)
 {
-	const char *firmware_name = NULL;
+	struct device *dev = &region->dev;
 	struct fpga_image_info *info;
+	const char *firmware_name;
 	int ret;
 
-	info = devm_kzalloc(&region->dev, sizeof(*info), GFP_KERNEL);
+	info = fpga_image_info_alloc(dev);
 	if (!info)
 		return -ENOMEM;
 
-	region->info = info;
-
 	/* Reject overlay if child FPGA Regions have firmware-name property */
 	ret = child_regions_with_firmware(nd->overlay);
 	if (ret)
@@ -382,7 +378,13 @@ static int fpga_region_notify_pre_apply(struct fpga_region *region,
 	if (of_property_read_bool(nd->overlay, "encrypted-fpga-config"))
 		info->flags |= FPGA_MGR_ENCRYPTED_BITSTREAM;
 
-	of_property_read_string(nd->overlay, "firmware-name", &firmware_name);
+	if (!of_property_read_string(nd->overlay, "firmware-name",
+				     &firmware_name)) {
+		info->firmware_name = devm_kstrdup(dev, firmware_name,
+						   GFP_KERNEL);
+		if (!info->firmware_name)
+			return -ENOMEM;
+	}
 
 	of_property_read_u32(nd->overlay, "region-unfreeze-timeout-us",
 			     &info->enable_timeout_us);
@@ -394,22 +396,33 @@ static int fpga_region_notify_pre_apply(struct fpga_region *region,
 			     &info->config_complete_timeout_us);
 
 	/* If FPGA was externally programmed, don't specify firmware */
-	if ((info->flags & FPGA_MGR_EXTERNAL_CONFIG) && firmware_name) {
+	if ((info->flags & FPGA_MGR_EXTERNAL_CONFIG) && info->firmware_name) {
 		pr_err("error: specified firmware and external-fpga-config");
+		fpga_image_info_free(info);
 		return -EINVAL;
 	}
 
 	/* FPGA is already configured externally.  We're done. */
-	if (info->flags & FPGA_MGR_EXTERNAL_CONFIG)
+	if (info->flags & FPGA_MGR_EXTERNAL_CONFIG) {
+		fpga_image_info_free(info);
 		return 0;
+	}
 
 	/* If we got this far, we should be programming the FPGA */
-	if (!firmware_name) {
+	if (!info->firmware_name) {
 		pr_err("should specify firmware-name or external-fpga-config\n");
+		fpga_image_info_free(info);
 		return -EINVAL;
 	}
 
-	return fpga_region_program_fpga(region, firmware_name, nd->overlay);
+	region->info = info;
+	ret = fpga_region_program_fpga(region, nd->overlay);
+	if (ret) {
+		fpga_image_info_free(info);
+		region->info = NULL;
+	}
+
+	return ret;
 }
 
 /**
@@ -426,7 +439,7 @@ static void fpga_region_notify_post_remove(struct fpga_region *region,
 {
 	fpga_bridges_disable(&region->bridge_list);
 	fpga_bridges_put(&region->bridge_list);
-	devm_kfree(&region->dev, region->info);
+	fpga_image_info_free(region->info);
 	region->info = NULL;
 }
 
diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
index bfa14bc..be371e6 100644
--- a/include/linux/fpga/fpga-mgr.h
+++ b/include/linux/fpga/fpga-mgr.h
@@ -1,7 +1,8 @@
 /*
  * FPGA Framework
  *
- *  Copyright (C) 2013-2015 Altera Corporation
+ *  Copyright (C) 2013-2016 Altera Corporation
+ *  Copyright (C) 2017 Intel Corporation
  *
  * This program is free software; you can redistribute it and/or modify it
  * under the terms and conditions of the GNU General Public License,
@@ -83,12 +84,22 @@ enum fpga_mgr_states {
  * @disable_timeout_us: maximum time to disable traffic through bridge (uSec)
  * @config_complete_timeout_us: maximum time for FPGA to switch to operating
  *	   status in the write_complete op.
+ * @firmware_name: name of FPGA image firmware file
+ * @sgt: scatter/gather table containing FPGA image
+ * @buf: contiguous buffer containing FPGA image
+ * @count: size of buf
+ * @dev: device that owns this
  */
 struct fpga_image_info {
 	u32 flags;
 	u32 enable_timeout_us;
 	u32 disable_timeout_us;
 	u32 config_complete_timeout_us;
+	char *firmware_name;
+	struct sg_table *sgt;
+	const char *buf;
+	size_t count;
+	struct device *dev;
 };
 
 /**
@@ -138,14 +149,11 @@ struct fpga_manager {
 
 #define to_fpga_manager(d) container_of(d, struct fpga_manager, dev)
 
-int fpga_mgr_buf_load(struct fpga_manager *mgr, struct fpga_image_info *info,
-		      const char *buf, size_t count);
-int fpga_mgr_buf_load_sg(struct fpga_manager *mgr, struct fpga_image_info *info,
-			 struct sg_table *sgt);
+struct fpga_image_info *fpga_image_info_alloc(struct device *dev);
 
-int fpga_mgr_firmware_load(struct fpga_manager *mgr,
-			   struct fpga_image_info *info,
-			   const char *image_name);
+void fpga_image_info_free(struct fpga_image_info *info);
+
+int fpga_mgr_load(struct fpga_manager *mgr, struct fpga_image_info *info);
 
 struct fpga_manager *of_fpga_mgr_get(struct device_node *node);
 
-- 
2.7.4