Re: [PATCH v5 3/6] staging: fpga manager: framework core

[Michal Simek]

Hi Alan,

first of all - there are these kernel-doc warnings.

Info(drivers/staging/fpga/fpga-mgr.c:37): Scanning doc for fpga_mgr_low_level_state
Warning(drivers/staging/fpga/fpga-mgr.c:43): No description found for return value of 'fpga_mgr_low_level_state'
Info(drivers/staging/fpga/fpga-mgr.c:51): Scanning doc for __fpga_mgr_reset
Warning(drivers/staging/fpga/fpga-mgr.c:55): No description found for return value of '__fpga_mgr_reset'
Info(drivers/staging/fpga/fpga-mgr.c:69): Scanning doc for fpga_mgr_reset
Warning(drivers/staging/fpga/fpga-mgr.c:73): No description found for return value of 'fpga_mgr_reset'
Info(drivers/staging/fpga/fpga-mgr.c:88): Scanning doc for __fpga_mgr_stage_init
Warning(drivers/staging/fpga/fpga-mgr.c:92): No description found for return value of '__fpga_mgr_stage_write_init'
Info(drivers/staging/fpga/fpga-mgr.c:108): Scanning doc for __fpga_mgr_stage_write
Warning(drivers/staging/fpga/fpga-mgr.c:115): No description found for return value of '__fpga_mgr_stage_write'
Info(drivers/staging/fpga/fpga-mgr.c:129): Scanning doc for __fpga_mgr_stage_complete
Warning(drivers/staging/fpga/fpga-mgr.c:133): No description found for return value of '__fpga_mgr_stage_write_complete'
Info(drivers/staging/fpga/fpga-mgr.c:151): Scanning doc for __fpga_mgr_write
Warning(drivers/staging/fpga/fpga-mgr.c:158): No description found for return value of '__fpga_mgr_write'
Info(drivers/staging/fpga/fpga-mgr.c:173): Scanning doc for fpga_mgr_write
Warning(drivers/staging/fpga/fpga-mgr.c:179): No description found for return value of 'fpga_mgr_write'
Info(drivers/staging/fpga/fpga-mgr.c:195): Scanning doc for fpga_mgr_firmware_write
Warning(drivers/staging/fpga/fpga-mgr.c:204): No description found for return value of 'fpga_mgr_firmware_write'
Info(drivers/staging/fpga/fpga-mgr.c:234): Scanning doc for fpga_mgr_name
Warning(drivers/staging/fpga/fpga-mgr.c:239): No description found for return value of 'fpga_mgr_name'
Info(drivers/staging/fpga/fpga-mgr.c:414): Scanning doc for fpga_mgr_register
Warning(drivers/staging/fpga/fpga-mgr.c:423): No description found for return value of 'fpga_mgr_register'
Info(drivers/staging/fpga/fpga-mgr.c:480): Scanning doc for fpga_mgr_remove
Warning(drivers/staging/fpga/fpga-mgr.c:484): No description found for parameter 'pdev'
Warning(drivers/staging/fpga/fpga-mgr.c:484): Excess function parameter 'dev' description in 'fpga_mgr_remove'


On 12/17/2014 05:54 PM, atull@xxxxxxxxxxxxxxxxxxxxx wrote:
> From: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> 
> Supports standard ops for low level FPGA drivers.
> Various manufacturors' FPGAs can be supported by adding low
> level drivers.  Each driver needs to register its ops
> using fpga_mgr_register().
> 
> Exports methods of doing operations to program  FPGAs. These
> should be sufficient for individual drivers to request FPGA
> programming directly if desired.
> 
> Adds a sysfs interface.  The sysfs interface can be compiled out
> where desired in production builds.
> 
> Resume is supported by calling low level driver's resume
> function, then reloading the firmware image.
> 
> The following are exported as GPL:
> * fpga_mgr_reset
>    Reset the FGPA.
> 
> * fpga_mgr_write
>    Write a image (in buffer) to the FPGA.
> 
> * fpga_mgr_firmware_write
>    Request firmware by file name and write it to the FPGA.
> 
> * fpga_mgr_name
>    Get name of FPGA manager.
> 
> * fpga_mgr_state
>    Get a state of framework as a string.
> 
> * fpga_mgr_register and fpga_mgr_remove
>    Register/unregister low level fpga manager driver.
> 
> The following sysfs files are created:
> * /sys/class/fpga_manager/<fpga>/name
>   Name of low level driver.
> 
> * /sys/class/fpga_manager/<fpga>/firmware
>   Name of FPGA image file to load using firmware class.
>   $ echo image.rbf > /sys/class/fpga_manager/<fpga>/firmware
> 
>   read: read back name of image file previous loaded
>   $ cat /sys/class/fpga_manager/<fpga>/firmware
> 
> * /sys/class/fpga_manager/<fpga>/reset
>   reset the FPGA
>   $ echo 1 > /sys/class/fpga_manager/<fpga>/reset
> 
> * /sys/class/fpga_manager/<fpga>/state
>   State of fpga framework state machine
> 
> Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> ---
> v2: s/mangager/manager/
>     check for invalid request_nr
>     add fpga reset interface
>     rework the state code
>     remove FPGA_MGR_FAIL flag
>     add _ERR states to fpga manager states enum
>     low level state op now returns a state enum value
>     initialize framework state from driver state op
>     remove unused fpga read stuff
>     merge sysfs.c into fpga-mgr.c
>     move suspend/resume from bus.c to fpga-mgr.c
> 
> v3: Add struct device to fpga_manager (not as a pointer)
>     Add to_fpga_manager
>     Don't get irq in fpga-mgr.c (let low level driver do it)
>     remove from struct fpga_manager: nr, np, parent
>     get rid of fpga_mgr_get_new_minor()
>     simplify fpga_manager_register:
>       reorder parameters
>       use dev instead of pdev
>     get rid of code that used to make more sense when this
>       was a char driver, don't alloc_chrdev_region
>     use a mutex instead of flags
> 
> v4: Move to drivers/staging
> 
> v5: Make some things be static
>     Kconfig: add 'if FPGA'
>     Makefile: s/fpga-mgr-core.o/fpga-mgr.o/
>     clean up includes
>     use enum fpga_mgr_states instead of int
>     static const char *state_str
>     use DEVICE_ATTR_RO/RW/WO and ATTRIBUTE_GROUPS
>     return -EINVAL instead of BUG_ON
>     move ida_simple_get after kzalloc
>     clean up fpga_mgr_remove
>     fpga-mgr.h: remove '#if IS_ENABLED(CONFIG_FPGA)'
>     add kernel-doc documentation
>     Move header to new include/linux/fpga folder
>     static const struct fpga_mgr_ops
>     dev_info msg simplified
> ---
>  drivers/staging/Kconfig         |    2 +
>  drivers/staging/Makefile        |    1 +
>  drivers/staging/fpga/Kconfig    |   24 ++
>  drivers/staging/fpga/Makefile   |   10 +
>  drivers/staging/fpga/fpga-mgr.c |  523 +++++++++++++++++++++++++++++++++++++++
>  include/linux/fpga/fpga-mgr.h   |  124 ++++++++++
>  6 files changed, 684 insertions(+)
>  create mode 100644 drivers/staging/fpga/Kconfig
>  create mode 100644 drivers/staging/fpga/Makefile
>  create mode 100644 drivers/staging/fpga/fpga-mgr.c
>  create mode 100644 include/linux/fpga/fpga-mgr.h
> 
> diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
> index 4690ae9..4338a4c 100644
> --- a/drivers/staging/Kconfig
> +++ b/drivers/staging/Kconfig
> @@ -108,4 +108,6 @@ source "drivers/staging/skein/Kconfig"
>  
>  source "drivers/staging/unisys/Kconfig"
>  
> +source "drivers/staging/fpga/Kconfig"
> +
>  endif # STAGING
> diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
> index c780a0e..43654a2 100644
> --- a/drivers/staging/Makefile
> +++ b/drivers/staging/Makefile
> @@ -46,3 +46,4 @@ obj-$(CONFIG_MTD_SPINAND_MT29F)	+= mt29f_spinand/
>  obj-$(CONFIG_GS_FPGABOOT)	+= gs_fpgaboot/
>  obj-$(CONFIG_CRYPTO_SKEIN)	+= skein/
>  obj-$(CONFIG_UNISYSSPAR)	+= unisys/
> +obj-$(CONFIG_FPGA)		+= fpga/
> diff --git a/drivers/staging/fpga/Kconfig b/drivers/staging/fpga/Kconfig
> new file mode 100644
> index 0000000..89ebafc
> --- /dev/null
> +++ b/drivers/staging/fpga/Kconfig
> @@ -0,0 +1,24 @@
> +#
> +# FPGA framework configuration
> +#
> +
> +menu "FPGA devices"
> +
> +config FPGA
> +	tristate "FPGA Framework"
> +	help
> +	  Say Y here if you want support for configuring FPGAs from the
> +	  kernel.  The FPGA framework adds a FPGA manager class and FPGA
> +	  manager drivers.
> +
> +if FPGA
> +
> +config FPGA_MGR_SYSFS
> +	bool "FPGA Manager SysFS Interface"
> +	depends on SYSFS
> +	help
> +	  FPGA Manager SysFS interface.
> +
> +endif # FPGA
> +
> +endmenu
> diff --git a/drivers/staging/fpga/Makefile b/drivers/staging/fpga/Makefile
> new file mode 100644
> index 0000000..ff6c677
> --- /dev/null
> +++ b/drivers/staging/fpga/Makefile
> @@ -0,0 +1,10 @@
> +#
> +# Makefile for the fpga framework and fpga manager drivers.
> +#
> +
> +fpga-mgr-core-y += fpga-mgr.o

remove this line - it is unused.

> +
> +# Core FPGA Manager Framework
> +obj-$(CONFIG_FPGA)			+= fpga-mgr.o
> +
> +# FPGA Manager Drivers
> diff --git a/drivers/staging/fpga/fpga-mgr.c b/drivers/staging/fpga/fpga-mgr.c
> new file mode 100644
> index 0000000..671b114
> --- /dev/null
> +++ b/drivers/staging/fpga/fpga-mgr.c
> @@ -0,0 +1,523 @@
> +/*
> + * FPGA Manager Core
> + *
> + *  Copyright (C) 2013-2014 Altera Corporation
> + *
> + * With code from the mailing list:
> + * Copyright (C) 2013 Xilinx, Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope 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.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +#include <linux/delay.h>
> +#include <linux/firmware.h>
> +#include <linux/fpga/fpga-mgr.h>
> +#include <linux/idr.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/pm.h>
> +#include <linux/slab.h>
> +
> +static DEFINE_MUTEX(fpga_mgr_mutex);
> +static DEFINE_IDA(fpga_mgr_ida);
> +static struct class *fpga_mgr_class;
> +
> +static LIST_HEAD(fpga_manager_list);
> +
> +/**
> + * fpga_mgr_low_level_state - get FPGA state from low level driver
> + * @mgr: fpga manager
> + *
> + * This will be used to initialize framework state
> + */
> +static enum fpga_mgr_states fpga_mgr_low_level_state(struct fpga_manager *mgr)
> +{
> +	if (!mgr || !mgr->mops || !mgr->mops->state)
> +		return FPGA_MGR_STATE_UNKNOWN;
> +
> +	return mgr->mops->state(mgr);
> +}
> +
> +/**
> + * __fpga_mgr_reset - unlocked version of fpga_mgr_reset
> + * @mgr: fpga manager
> + */
> +static int __fpga_mgr_reset(struct fpga_manager *mgr)
> +{
> +	int ret;
> +
> +	if (!mgr->mops->reset)
> +		return -EINVAL;
> +
> +	ret = mgr->mops->reset(mgr);
> +
> +	mgr->state = fpga_mgr_low_level_state(mgr);
> +
> +	return ret;
> +}
> +
> +/**
> + * fpga_mgr_reset - reset the fpga
> + * @mgr: fpga manager
> + */
> +int fpga_mgr_reset(struct fpga_manager *mgr)
> +{
> +	int ret;
> +
> +	if (!mutex_trylock(&mgr->lock))
> +		return -EBUSY;
> +
> +	ret = __fpga_mgr_reset(mgr);
> +
> +	mutex_unlock(&mgr->lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(fpga_mgr_reset);
> +
> +/**
> + * __fpga_mgr_stage_init - prepare fpga for configuration
> + * @mgr: fpga manager
> + */
> +static int __fpga_mgr_stage_write_init(struct fpga_manager *mgr)
> +{
> +	int ret;
> +
> +	if (mgr->mops->write_init) {
> +		mgr->state = FPGA_MGR_STATE_WRITE_INIT;
> +		ret = mgr->mops->write_init(mgr);
> +		if (ret) {
> +			mgr->state = FPGA_MGR_STATE_WRITE_INIT_ERR;
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * __fpga_mgr_stage_write - write buffer to fpga
> + * @mgr: fpga manager
> + * @buf: buffer contain fpga image
> + * @count: byte count of buf
> + */
> +static int __fpga_mgr_stage_write(struct fpga_manager *mgr, const char *buf,
> +				  size_t count)
> +{
> +	int ret;
> +
> +	mgr->state = FPGA_MGR_STATE_WRITE;
> +	ret = mgr->mops->write(mgr, buf, count);
> +	if (ret) {
> +		mgr->state = FPGA_MGR_STATE_WRITE_ERR;
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
> +/**
> + * __fpga_mgr_stage_complete - after writing, place fpga in operating state
> + * @mgr: fpga manager
> + */
> +static int __fpga_mgr_stage_write_complete(struct fpga_manager *mgr)
> +{
> +	int ret;
> +
> +	if (mgr->mops->write_complete) {
> +		mgr->state = FPGA_MGR_STATE_WRITE_COMPLETE;
> +		ret = mgr->mops->write_complete(mgr);
> +		if (ret) {
> +			mgr->state = FPGA_MGR_STATE_WRITE_COMPLETE_ERR;
> +			return ret;
> +		}
> +	}
> +
> +	mgr->state = fpga_mgr_low_level_state(mgr);
> +
> +	return 0;
> +}
> +
> +/**
> + * __fpga_mgr_write - whole fpga image write cycle
> + * @mgr: fpga manager
> + * @buf: buffer contain fpga image
> + * @count: byte count of buf
> + */
> +static int __fpga_mgr_write(struct fpga_manager *mgr, const char *buf,
> +			    size_t count)
> +{
> +	int ret;
> +
> +	ret = __fpga_mgr_stage_write_init(mgr);
> +	if (ret)
> +		return ret;
> +
> +	ret = __fpga_mgr_stage_write(mgr, buf, count);
> +	if (ret)
> +		return ret;
> +
> +	return __fpga_mgr_stage_write_complete(mgr);
> +}
> +
> +/**
> + * fpga_mgr_write - do complete fpga image write cycle
> + * @mgr: fpga manager
> + * @buf: buffer contain fpga image
> + * @count: byte count of buf
> + */
> +int fpga_mgr_write(struct fpga_manager *mgr, const char *buf, size_t count)
> +{
> +	int ret;
> +
> +	if (!mutex_trylock(&mgr->lock))
> +		return -EBUSY;
> +
> +	dev_info(&mgr->dev, "writing buffer to %s\n", mgr->name);
> +
> +	ret = __fpga_mgr_write(mgr, buf, count);
> +	mutex_unlock(&mgr->lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(fpga_mgr_write);
> +
> +/**
> + * fpga_mgr_firmware_write - request firmware and write to fpga
> + * @mgr: fpga manager
> + * @image_name: name of image file on the firmware search path
> + *
> + * Grab lock, request firmware, and write out to the FPGA.
> + * Update the state before each step to provide info on what step
> + * failed if there is a failure.
> + */
> +int fpga_mgr_firmware_write(struct fpga_manager *mgr, const char *image_name)
> +{
> +	const struct firmware *fw;
> +	int ret;
> +
> +	if (!mutex_trylock(&mgr->lock))
> +		return -EBUSY;
> +
> +	dev_info(&mgr->dev, "writing %s to %s\n", image_name, mgr->name);
> +
> +	mgr->state = FPGA_MGR_STATE_FIRMWARE_REQ;
> +	ret = request_firmware(&fw, image_name, &mgr->dev);
> +	if (ret) {
> +		mgr->state = FPGA_MGR_STATE_FIRMWARE_REQ_ERR;
> +		goto fw_wr_exit;
> +	}
> +
> +	ret = __fpga_mgr_write(mgr, fw->data, fw->size);
> +	if (ret)
> +		goto fw_wr_exit;
> +
> +	strcpy(mgr->image_name, image_name);
> +
> +fw_wr_exit:
> +	mutex_unlock(&mgr->lock);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(fpga_mgr_firmware_write);
> +
> +/**
> + * fpga_mgr_name - returns the fpga manager name
> + * @mgr: fpga manager
> + * @buf: buffer to receive the name
> + */
> +int fpga_mgr_name(struct fpga_manager *mgr, char *buf)
> +{
> +	if (!mgr)
> +		return -ENODEV;
> +
> +	return sprintf(buf, "%s\n", mgr->name);
> +}
> +EXPORT_SYMBOL_GPL(fpga_mgr_name);
> +
> +#if IS_ENABLED(CONFIG_FPGA_MGR_SYSFS)

remove this line

> +static const char * const state_str[] = {
> +	[FPGA_MGR_STATE_UNKNOWN] =		"unknown",
> +	[FPGA_MGR_STATE_POWER_OFF] =		"power_off",
> +	[FPGA_MGR_STATE_POWER_UP] =		"power_up",
> +	[FPGA_MGR_STATE_RESET] =		"reset",
> +
> +	/* write sequence */
> +	[FPGA_MGR_STATE_FIRMWARE_REQ] =		"firmware_request",
> +	[FPGA_MGR_STATE_FIRMWARE_REQ_ERR] =	"firmware_request_err",
> +	[FPGA_MGR_STATE_WRITE_INIT] =		"write_init",
> +	[FPGA_MGR_STATE_WRITE_INIT_ERR] =	"write_init_err",
> +	[FPGA_MGR_STATE_WRITE] =		"write",
> +	[FPGA_MGR_STATE_WRITE_ERR] =		"write_err",
> +	[FPGA_MGR_STATE_WRITE_COMPLETE] =	"write_complete",
> +	[FPGA_MGR_STATE_WRITE_COMPLETE_ERR] =	"write_complete_err",
> +
> +	[FPGA_MGR_STATE_OPERATING] =		"operating",
> +};
> +
> +/*
> + * class attributes
> + */
> +static ssize_t name_show(struct device *dev,
> +			 struct device_attribute *attr, char *buf)
> +{
> +	struct fpga_manager *mgr = to_fpga_manager(dev);
> +
> +	return fpga_mgr_name(mgr, buf);
> +}
> +
> +static ssize_t state_show(struct device *dev,
> +			  struct device_attribute *attr, char *buf)
> +{
> +	struct fpga_manager *mgr = to_fpga_manager(dev);
> +
> +	return sprintf(buf, "%s\n", state_str[mgr->state]);
> +}
> +
> +static ssize_t firmware_show(struct device *dev,
> +			     struct device_attribute *attr, char *buf)
> +{
> +	struct fpga_manager *mgr = to_fpga_manager(dev);
> +
> +	return sprintf(buf, "%s\n", mgr->image_name);
> +}
> +
> +static ssize_t firmware_store(struct device *dev,
> +			      struct device_attribute *attr,
> +			      const char *buf, size_t count)
> +{
> +	struct fpga_manager *mgr = to_fpga_manager(dev);
> +	unsigned int len;
> +	char image_name[NAME_MAX];
> +	int ret;
> +
> +	/* lose terminating \n */
> +	strcpy(image_name, buf);
> +	len = strlen(image_name);
> +	if (image_name[len - 1] == '\n')
> +		image_name[len - 1] = 0;
> +
> +	ret = fpga_mgr_firmware_write(mgr, image_name);
> +	if (ret)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static ssize_t reset_store(struct device *dev,
> +			   struct device_attribute *attr,
> +			   const char *buf, size_t count)
> +{
> +	struct fpga_manager *mgr = to_fpga_manager(dev);
> +	unsigned long val;
> +	int ret;
> +
> +	ret = kstrtoul(buf, 0, &val);
> +	if (ret)
> +		return ret;
> +
> +	if (val == 1) {
> +		ret = fpga_mgr_reset(mgr);
> +		if (ret)
> +			return ret;
> +	} else {
> +		return -EINVAL;
> +	}
> +
> +	return count;
> +}
> +
> +static DEVICE_ATTR_RO(name);
> +static DEVICE_ATTR_RO(state);
> +static DEVICE_ATTR_RW(firmware);
> +static DEVICE_ATTR_WO(reset);
> +
> +static struct attribute *fpga_mgr_attrs[] = {
> +	&dev_attr_name.attr,
> +	&dev_attr_state.attr,
> +	&dev_attr_firmware.attr,
> +	&dev_attr_reset.attr,
> +	NULL,
> +};
> +ATTRIBUTE_GROUPS(fpga_mgr);
> +#else
> +#define fpga_mgr_groups NULL
> +#endif /* CONFIG_FPGA_MGR_SYSFS */

remove these 3 lines and look below.

> +
> +static int fpga_mgr_suspend(struct device *dev)
> +{
> +	struct fpga_manager *mgr = to_fpga_manager(dev);
> +
> +	if (!mgr)
> +		return -ENODEV;
> +
> +	if (mgr->mops->suspend)
> +		return mgr->mops->suspend(mgr);
> +
> +	return 0;
> +}
> +
> +static int fpga_mgr_resume(struct device *dev)
> +{
> +	struct fpga_manager *mgr = to_fpga_manager(dev);
> +	int ret = 0;
> +
> +	if (!mgr)
> +		return -ENODEV;
> +
> +	if (mgr->mops->resume) {
> +		ret = mgr->mops->resume(mgr);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	if (strlen(mgr->image_name) != 0)
> +		fpga_mgr_firmware_write(mgr, mgr->image_name);
> +
> +	return 0;
> +}
> +
> +static const struct dev_pm_ops fpga_mgr_dev_pm_ops = {
> +	.suspend	= fpga_mgr_suspend,
> +	.resume		= fpga_mgr_resume,
> +};
> +
> +static void fpga_mgr_dev_release(struct device *dev)
> +{
> +	struct fpga_manager *mgr = to_fpga_manager(dev);
> +
> +	dev_dbg(dev, "releasing '%s'\n", mgr->name);
> +
> +	if (mgr->mops->fpga_remove)
> +		mgr->mops->fpga_remove(mgr);
> +
> +	mgr->mops = NULL;
> +
> +	mutex_lock(&fpga_mgr_mutex);
> +	list_del(&mgr->list);
> +	mutex_unlock(&fpga_mgr_mutex);
> +
> +	ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
> +	kfree(mgr);
> +}
> +
> +/**
> + * fpga_mgr_register - register a low level fpga manager driver
> + * @dev: fpga manager device
> + * @name: fpga manager name
> + * @mops: pointer to structure of fpga manager ops
> + * @priv: fpga manager private data
> + */
> +int fpga_mgr_register(struct device *dev, const char *name,
> +		      const struct fpga_manager_ops *mops,
> +		      void *priv)
> +{
> +	struct fpga_manager *mgr;
> +	int id, ret;
> +
> +	if (!mops || !name || !strlen(name))
> +		return -EINVAL;
> +
> +	mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
> +	if (!mgr)
> +		return -ENOMEM;
> +
> +	id = ida_simple_get(&fpga_mgr_ida, 0, 0, GFP_KERNEL);
> +	if (id < 0)
> +		return id;
> +
> +	mutex_init(&mgr->lock);
> +
> +	mgr->name = name;
> +	mgr->mops = mops;
> +	mgr->priv = priv;
> +
> +	/*
> +	 * Initialize framework state by requesting low level driver read state
> +	 * from device.  FPGA may be in reset mode or may have been programmed
> +	 * by bootloader or EEPROM.
> +	 */
> +	mgr->state = fpga_mgr_low_level_state(mgr);
> +
> +	INIT_LIST_HEAD(&mgr->list);
> +	mutex_lock(&fpga_mgr_mutex);
> +	list_add(&mgr->list, &fpga_manager_list);
> +	mutex_unlock(&fpga_mgr_mutex);
> +
> +	device_initialize(&mgr->dev);
> +	mgr->dev.class = fpga_mgr_class;
> +	mgr->dev.parent = dev;
> +	mgr->dev.of_node = dev->of_node;
> +	mgr->dev.release = fpga_mgr_dev_release;
> +	mgr->dev.id = id;
> +	dev_set_name(&mgr->dev, "%d", id);
> +	ret = device_add(&mgr->dev);
> +	if (ret)
> +		goto error_device;
> +
> +	dev_info(&mgr->dev, "%s registered\n", mgr->name);
> +
> +	return 0;
> +
> +error_device:
> +	ida_simple_remove(&fpga_mgr_ida, id);
> +	kfree(mgr);
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(fpga_mgr_register);
> +
> +/**
> + * fpga_mgr_remove - remove a low level fpga manager driver
> + * @dev: fpga manager device
> + */
> +void fpga_mgr_remove(struct platform_device *pdev)
> +{
> +	struct list_head *tmp;
> +	struct fpga_manager *mgr = NULL;
> +
> +	list_for_each(tmp, &fpga_manager_list) {
> +		mgr = list_entry(tmp, struct fpga_manager, list);
> +		if (mgr->dev.parent == &pdev->dev) {
> +			device_unregister(&mgr->dev);
> +			break;
> +		}
> +	}
> +}
> +EXPORT_SYMBOL_GPL(fpga_mgr_remove);
> +
> +static int __init fpga_mgr_dev_init(void)
> +{
> +	pr_info("FPGA Manager framework driver\n");
> +
> +	fpga_mgr_class = class_create(THIS_MODULE, "fpga_manager");
> +	if (IS_ERR(fpga_mgr_class))
> +		return PTR_ERR(fpga_mgr_class);
> +
> +	fpga_mgr_class->dev_groups = fpga_mgr_groups;


Write this here.
       if (IS_ENABLED(CONFIG_FPGA_MGR_SYSFS)) {
             fpga_mgr_class->dev_groups = fpga_mgr_groups;
       }

I have tested it and it is working just fine. You can compile this
driver with SYSFS=n
The whole code is built and config option just export it.
I think it is better than having #if there.

Greg: Is there any problem with this solution?

BTW: I have pushed my branch to zero day testing system to get better coverage

Thanks,
Michal


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