Re: [PATCH V3 XRT Alveo 06/18] fpga: xrt: platform driver infrastructure

Max Zhen
2021-03-08T20:36:57Z

Hi Tom,

On 2/25/21 1:59 PM, Tom Rix wrote:
> CAUTION: This message has originated from an External Source. Please use proper judgment and caution when opening attachments, clicking links, or responding to this email.
>
>
> On 2/17/21 10:40 PM, Lizhi Hou wrote:
>> infrastructure code providing APIs for managing leaf driver instance
>> groups, facilitating inter-leaf driver calls and root calls, managing leaf
>> driver device nodes.
>>
>> Signed-off-by: Sonal Santan<sonal.santan@xilinx.com>
>> Signed-off-by: Max Zhen<max.zhen@xilinx.com>
>> Signed-off-by: Lizhi Hou<lizhih@xilinx.com>
>> ---
>> drivers/fpga/xrt/include/events.h | 48 ++
>> drivers/fpga/xrt/include/subdev_id.h | 43 ++
>> drivers/fpga/xrt/include/xleaf.h | 276 +++++++++
>> drivers/fpga/xrt/lib/cdev.c | 231 +++++++
>> drivers/fpga/xrt/lib/subdev.c | 871 +++++++++++++++++++++++++++
>> drivers/fpga/xrt/lib/subdev_pool.h | 53 ++
>> drivers/fpga/xrt/lib/xroot.c | 598 ++++++++++++++++++
>> 7 files changed, 2120 insertions(+)
>> create mode 100644 drivers/fpga/xrt/include/events.h
>> create mode 100644 drivers/fpga/xrt/include/subdev_id.h
>> create mode 100644 drivers/fpga/xrt/include/xleaf.h
>> create mode 100644 drivers/fpga/xrt/lib/cdev.c
>> create mode 100644 drivers/fpga/xrt/lib/subdev.c
>> create mode 100644 drivers/fpga/xrt/lib/subdev_pool.h
>> create mode 100644 drivers/fpga/xrt/lib/xroot.c
>>
>> diff --git a/drivers/fpga/xrt/include/events.h b/drivers/fpga/xrt/include/events.h
>> new file mode 100644
>> index 000000000000..2a9aae8bceb4
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/include/events.h
>> @@ -0,0 +1,48 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Header file for Xilinx Runtime (XRT) driver
> general problem with generic, low information comments

This is removed.

>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + * Cheng Zhen<maxz@xilinx.com>
>> + */
>> +
>> +#ifndef _XRT_EVENTS_H_
>> +#define _XRT_EVENTS_H_
>> +
>> +#include <linux/platform_device.h>
> why is platform_device.h needed ?

It is not needed. Removed.

>> +#include "subdev_id.h"
>> +
>> +/*
>> + * Event notification.
>> + */
>> +enum xrt_events {
>> + XRT_EVENT_TEST = 0, /* for testing */
>> + /*
>> + * Events related to specific subdev
>> + * Callback arg: struct xrt_event_arg_subdev
>> + */
>> + XRT_EVENT_POST_CREATION,
>> + XRT_EVENT_PRE_REMOVAL,
>> + /*
>> + * Events related to change of the whole board
>> + * Callback arg: <none>
>> + */
>> + XRT_EVENT_PRE_HOT_RESET,
>> + XRT_EVENT_POST_HOT_RESET,
>> + XRT_EVENT_PRE_GATE_CLOSE,
>> + XRT_EVENT_POST_GATE_OPEN,
>> +};
>> +
>> +struct xrt_event_arg_subdev {
>> + enum xrt_subdev_id xevt_subdev_id;
>> + int xevt_subdev_instance;
>> +};
>> +
>> +struct xrt_event {
>> + enum xrt_events xe_evt;
>> + struct xrt_event_arg_subdev xe_subdev;
>> +};
>> +
>> +#endif /* _XRT_EVENTS_H_ */
>> diff --git a/drivers/fpga/xrt/include/subdev_id.h b/drivers/fpga/xrt/include/subdev_id.h
>> new file mode 100644
>> index 000000000000..6205a9f26196
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/include/subdev_id.h
>> @@ -0,0 +1,43 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Header file for Xilinx Runtime (XRT) driver
>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + * Cheng Zhen<maxz@xilinx.com>
>> + */
>> +
>> +#ifndef _XRT_SUBDEV_ID_H_
>> +#define _XRT_SUBDEV_ID_H_
>> +
>> +/*
>> + * Every subdev driver should have an ID for others to refer to it.
> driver has an ID

Sure.

>> + * There can be unlimited number of instances of a subdev driver. A
> unlimited? change to 'multiple'

Sure.

>> + * <subdev_id, subdev_instance> tuple should be a unique identification of
> tuple is a unique

Sure.

>> + * a specific instance of a subdev driver.
>> + * NOTE: PLEASE do not change the order of IDs. Sub devices in the same
>> + * group are initialized by this order.
> why does the order matter? the enums are all initialized

Right. Will remove this statement.

>> + */
>> +enum xrt_subdev_id {
>> + XRT_SUBDEV_GRP = 0,
>> + XRT_SUBDEV_VSEC = 1,
>> + XRT_SUBDEV_VSEC_GOLDEN = 2,
>> + XRT_SUBDEV_DEVCTL = 3,
>> + XRT_SUBDEV_AXIGATE = 4,
>> + XRT_SUBDEV_ICAP = 5,
>> + XRT_SUBDEV_TEST = 6,
>> + XRT_SUBDEV_MGMT_MAIN = 7,
>> + XRT_SUBDEV_QSPI = 8,
>> + XRT_SUBDEV_MAILBOX = 9,
>> + XRT_SUBDEV_CMC = 10,
>> + XRT_SUBDEV_CALIB = 11,
>> + XRT_SUBDEV_CLKFREQ = 12,
>> + XRT_SUBDEV_CLOCK = 13,
>> + XRT_SUBDEV_SRSR = 14,
>> + XRT_SUBDEV_UCS = 15,
>> + XRT_SUBDEV_NUM = 16, /* Total number of subdevs. */
>> + XRT_ROOT = -1, /* Special ID for root driver. */
>> +};
>> +
>> +#endif /* _XRT_SUBDEV_ID_H_ */
>> diff --git a/drivers/fpga/xrt/include/xleaf.h b/drivers/fpga/xrt/include/xleaf.h
>> new file mode 100644
>> index 000000000000..10215a75d474
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/include/xleaf.h
>> @@ -0,0 +1,276 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Header file for Xilinx Runtime (XRT) driver
>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + * Cheng Zhen<maxz@xilinx.com>
>> + * Sonal Santan<sonal.santan@xilinx.com>
>> + */
>> +
>> +#ifndef _XRT_XLEAF_H_
>> +#define _XRT_XLEAF_H_
>> +
>> +#include <linux/mod_devicetable.h>
> not needed

Removed.

>> +#include <linux/platform_device.h>
>> +#include <linux/fs.h>
>> +#include <linux/cdev.h>
>> +#include <linux/pci.h>
> not needed
>
> check if includes are actually needed.

Removed these headers. They are not needed. The rest are needed.

>> +#include <linux/libfdt_env.h>
>> +#include "libfdt.h"
>> +#include "subdev_id.h"
>> +#include "xroot.h"
>> +#include "events.h"
>> +
>> +/* All subdev drivers should use below common routines to print out msg. */
>> +#define DEV(pdev) (&(pdev)->dev)
>> +#define DEV_PDATA(pdev) \
>> + ((struct xrt_subdev_platdata *)dev_get_platdata(DEV(pdev)))
>> +#define DEV_DRVDATA(pdev) \
>> + ((struct xrt_subdev_drvdata *) \
>> + platform_get_device_id(pdev)->driver_data)
>> +#define FMT_PRT(prt_fn, pdev, fmt, args...) \
>> + ({typeof(pdev) (_pdev) = (pdev); \
>> + prt_fn(DEV(_pdev), "%s %s: " fmt, \
>> + DEV_PDATA(_pdev)->xsp_root_name, __func__, ##args); })
>> +#define xrt_err(pdev, fmt, args...) FMT_PRT(dev_err, pdev, fmt, ##args)
>> +#define xrt_warn(pdev, fmt, args...) FMT_PRT(dev_warn, pdev, fmt, ##args)
>> +#define xrt_info(pdev, fmt, args...) FMT_PRT(dev_info, pdev, fmt, ##args)
>> +#define xrt_dbg(pdev, fmt, args...) FMT_PRT(dev_dbg, pdev, fmt, ##args)
>> +
>> +/* Starting IOCTL for common IOCTLs implemented by all leaves. */
>> +#define XRT_XLEAF_COMMON_BASE 0
>> +/* Starting IOCTL for leaves' specific IOCTLs. */
>> +#define XRT_XLEAF_CUSTOM_BASE 64
>> +enum xrt_xleaf_common_ioctl_cmd {
>> + XRT_XLEAF_EVENT = XRT_XLEAF_COMMON_BASE,
>> +};
>> +
>> +/*
>> + * If populated by subdev driver, infra will handle the mechanics of
>> + * char device (un)registration.
>> + */
>> +enum xrt_subdev_file_mode {
>> + /* Infra create cdev, default file name */
>> + XRT_SUBDEV_FILE_DEFAULT = 0,
>> + /* Infra create cdev, need to encode inst num in file name */
>> + XRT_SUBDEV_FILE_MULTI_INST,
>> + /* No auto creation of cdev by infra, leaf handles it by itself */
>> + XRT_SUBDEV_FILE_NO_AUTO,
>> +};
>> +
>> +struct xrt_subdev_file_ops {
>> + const struct file_operations xsf_ops;
>> + dev_t xsf_dev_t;
>> + const char *xsf_dev_name;
>> + enum xrt_subdev_file_mode xsf_mode;
>> +};
>> +
>> +/*
>> + * Subdev driver callbacks populated by subdev driver.
>> + */
>> +struct xrt_subdev_drv_ops {
>> + /*
>> + * Per driver instance callback. The pdev points to the instance.
>> + * If defined these are called by other leaf drivers.
> If defined,

Sure.

>> + * Note that root driver may call into xsd_ioctl of a group driver.
>> + */
>> + int (*xsd_ioctl)(struct platform_device *pdev, u32 cmd, void *arg);
>> +};
>> +
>> +/*
>> + * Defined and populated by subdev driver, exported as driver_data in
>> + * struct platform_device_id.
>> + */
>> +struct xrt_subdev_drvdata {
>> + struct xrt_subdev_file_ops xsd_file_ops;
>> + struct xrt_subdev_drv_ops xsd_dev_ops;
>> +};
>> +
>> +/*
>> + * Partially initialized by the parent driver, then, passed in as subdev driver's
>> + * platform data when creating subdev driver instance by calling platform
>> + * device register API (platform_device_register_data() or the likes).
>> + *
>> + * Once device register API returns, platform driver framework makes a copy of
>> + * this buffer and maintains its life cycle. The content of the buffer is
>> + * completely owned by subdev driver.
>> + *
>> + * Thus, parent driver should be very careful when it touches this buffer
>> + * again once it's handed over to subdev driver. And the data structure
>> + * should not contain pointers pointing to buffers that is managed by
>> + * other or parent drivers since it could have been freed before platform
>> + * data buffer is freed by platform driver framework.
> This sounds complicated and risky, why have two copies ?

There is only one copy. The buffer used for registering the platform
device will be freed by parent.

>> + */
>> +struct xrt_subdev_platdata {
>> + /*
>> + * Per driver instance callback. The pdev points to the instance.
>> + * Should always be defined for subdev driver to get service from root.
>> + */
>> + xrt_subdev_root_cb_t xsp_root_cb;
>> + void *xsp_root_cb_arg;
>> +
>> + /* Something to associate w/ root for msg printing. */
>> + const char *xsp_root_name;
>> +
>> + /*
>> + * Char dev support for this subdev instance.
>> + * Initialized by subdev driver.
>> + */
>> + struct cdev xsp_cdev;
>> + struct device *xsp_sysdev;
>> + struct mutex xsp_devnode_lock; /* devnode lock */
>> + struct completion xsp_devnode_comp;
>> + int xsp_devnode_ref;
>> + bool xsp_devnode_online;
>> + bool xsp_devnode_excl;
>> +
>> + /*
>> + * Subdev driver specific init data. The buffer should be embedded
>> + * in this data structure buffer after dtb, so that it can be freed
>> + * together with platform data.
>> + */
>> + loff_t xsp_priv_off; /* Offset into this platform data buffer. */
>> + size_t xsp_priv_len;
>> +
>> + /*
>> + * Populated by parent driver to describe the device tree for
>> + * the subdev driver to handle. Should always be last one since it's
>> + * of variable length.
>> + */
>> + char xsp_dtb[sizeof(struct fdt_header)];
> could be xsp_dtb[1] and save including the fdt headers just to get a size that doesn't matter.

Sure. Will change the code and remove the included headers.

>> +};
>> +
>> +/*
>> + * this struct define the endpoints belong to the same subdevice
>> + */
>> +struct xrt_subdev_ep_names {
>> + const char *ep_name;
>> + const char *regmap_name;
>> +};
>> +
>> +struct xrt_subdev_endpoints {
>> + struct xrt_subdev_ep_names *xse_names;
>> + /* minimum number of endpoints to support the subdevice */
>> + u32 xse_min_ep;
> see earlier comment about needed a null entry and checking for it.
>
> a 'size' element would be better here.

See my reply to your earlier comment. Can't change here.

>> +};
>> +
>> +struct subdev_match_arg {
>> + enum xrt_subdev_id id;
>> + int instance;
>> +};
>> +
>> +bool xleaf_has_endpoint(struct platform_device *pdev, const char *endpoint_name);
>> +struct platform_device *xleaf_get_leaf(struct platform_device *pdev,
>> + xrt_subdev_match_t cb, void *arg);
>> +
>> +static inline bool subdev_match(enum xrt_subdev_id id, struct platform_device *pdev, void *arg)
>> +{
>> + const struct subdev_match_arg *a = (struct subdev_match_arg *)arg;
>> + bool ret = (id == a->id && (pdev->id == a->instance || PLATFORM_DEVID_NONE == a->instance));
> This statement is too complicated, turn this into an if-else

Sure.

>> +
>> + return ret;
>> +}
>> +
>> +static inline bool xrt_subdev_match_epname(enum xrt_subdev_id id,
>> + struct platform_device *pdev, void *arg)
>> +{
>> + return xleaf_has_endpoint(pdev, arg);
> This function is used only once.
>
> Just inline the function to the caller and remove this function.

This function is used by being passed as a function pointer to another
function. I can't inline it.

>> +}
>> +
>> +static inline struct platform_device *
>> +xleaf_get_leaf_by_id(struct platform_device *pdev,
>> + enum xrt_subdev_id id, int instance)
>> +{
>> + struct subdev_match_arg arg = { id, instance };
>> +
>> + return xleaf_get_leaf(pdev, subdev_match, &arg);
>> +}
>> +
>> +static inline struct platform_device *
>> +xleaf_get_leaf_by_epname(struct platform_device *pdev, const char *name)
>> +{
>> + return xleaf_get_leaf(pdev, xrt_subdev_match_epname, (void *)name);
>> +}
>> +
>> +static inline int xleaf_ioctl(struct platform_device *tgt, u32 cmd, void *arg)
>> +{
>> + struct xrt_subdev_drvdata *drvdata = DEV_DRVDATA(tgt);
>> +
>> + return (*drvdata->xsd_dev_ops.xsd_ioctl)(tgt, cmd, arg);
>> +}
>> +
>> +int xleaf_put_leaf(struct platform_device *pdev,
>> + struct platform_device *leaf);
>> +int xleaf_create_group(struct platform_device *pdev, char *dtb);
>> +int xleaf_destroy_group(struct platform_device *pdev, int instance);
>> +int xleaf_wait_for_group_bringup(struct platform_device *pdev);
>> +void xleaf_hot_reset(struct platform_device *pdev);
>> +int xleaf_broadcast_event(struct platform_device *pdev,
>> + enum xrt_events evt, bool async);
>> +void xleaf_get_barres(struct platform_device *pdev,
>> + struct resource **res, uint bar_idx);
>> +void xleaf_get_root_id(struct platform_device *pdev,
>> + unsigned short *vendor, unsigned short *device,
>> + unsigned short *subvendor, unsigned short *subdevice);
>> +struct device *xleaf_register_hwmon(struct platform_device *pdev,
>> + const char *name, void *drvdata,
>> + const struct attribute_group **grps);
>> +void xleaf_unregister_hwmon(struct platform_device *pdev, struct device *hwmon);
> could better organize these decl's alphabetically.

Sure.

> Also not intermix inlines and decls.

These decls are used in inlines, so can't reorder.

>> +
>> +/*
>> + * Character device helper APIs for use by leaf drivers
>> + */
>> +static inline bool xleaf_devnode_enabled(struct xrt_subdev_drvdata *drvdata)
>> +{
>> + return drvdata && drvdata->xsd_file_ops.xsf_ops.open;
>> +}
>> +
>> +int xleaf_devnode_create(struct platform_device *pdev,
>> + const char *file_name, const char *inst_name);
>> +int xleaf_devnode_destroy(struct platform_device *pdev);
>> +
>> +struct platform_device *xleaf_devnode_open_excl(struct inode *inode);
>> +struct platform_device *xleaf_devnode_open(struct inode *inode);
>> +void xleaf_devnode_close(struct inode *inode);
>> +
>> +/* Helpers. */
>> +static inline void xrt_memcpy_fromio(void *buf, void __iomem *iomem, u32 size)
>> +{
> Replace with mmio_insl/outsl

No, I can't call mmio_insl/outsl here or even
ioread32_rep()/iowrite32_rep(). These function will not increase port
address inside the loop. But, the implementation we need is like
memcpy() - both src and dst will be increased during the loop.

>> + int i;
>> +
>> + WARN_ON(size & 0x3);
>> + for (i = 0; i < size / 4; i++)
>> + ((u32 *)buf)[i] = ioread32((char *)(iomem) + sizeof(u32) * i);
>> +}
>> +
>> +static inline void xrt_memcpy_toio(void __iomem *iomem, void *buf, u32 size)
>> +{
>> + int i;
>> +
>> + WARN_ON(size & 0x3);
>> + for (i = 0; i < size / 4; i++)
>> + iowrite32(((u32 *)buf)[i], ((char *)(iomem) + sizeof(u32) * i));
>> +}
>> +
>> +int xleaf_register_driver(enum xrt_subdev_id id, struct platform_driver *drv,
>> + struct xrt_subdev_endpoints *eps);
>> +void xleaf_unregister_driver(enum xrt_subdev_id id);
>> +
>> +/* Module's init/fini routines for leaf driver in xrt-lib module */
>> +void group_leaf_init_fini(bool init);
>> +void vsec_leaf_init_fini(bool init);
>> +void vsec_golden_leaf_init_fini(bool init);
>> +void devctl_leaf_init_fini(bool init);
>> +void axigate_leaf_init_fini(bool init);
>> +void icap_leaf_init_fini(bool init);
>> +void calib_leaf_init_fini(bool init);
>> +void qspi_leaf_init_fini(bool init);
>> +void mailbox_leaf_init_fini(bool init);
>> +void cmc_leaf_init_fini(bool init);
>> +void clkfreq_leaf_init_fini(bool init);
>> +void clock_leaf_init_fini(bool init);
>> +void ucs_leaf_init_fini(bool init);
> Shouldn't these be in the specific leaf drv ?

If the leaf drivers are standalone .ko, yes. But these are for leaf
drivers inside xrt-lib.ko, so we need them here to be called inside
xrt-lib.ko's __init/__fini routine.

>> +
>> +#endif /* _XRT_LEAF_H_ */
>> diff --git a/drivers/fpga/xrt/lib/cdev.c b/drivers/fpga/xrt/lib/cdev.c
>> new file mode 100644
>> index 000000000000..7f104ab3d527
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/lib/cdev.c
>> @@ -0,0 +1,231 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Xilinx Alveo FPGA device node helper functions.
>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + * Cheng Zhen<maxz@xilinx.com>
>> + */
>> +
>> +#include "xleaf.h"
>> +
>> +extern struct class *xrt_class;
>> +
>> +#define XRT_CDEV_DIR "xfpga"
> 'xfpga' is not very unique, maybe 'xrt' ?

This is to make sure it's compatible with XRT's user space utilities,
which also works with other version of drivers (they all use xfpga).

>> +#define INODE2PDATA(inode) \
>> + container_of((inode)->i_cdev, struct xrt_subdev_platdata, xsp_cdev)
>> +#define INODE2PDEV(inode) \
>> + to_platform_device(kobj_to_dev((inode)->i_cdev->kobj.parent))
>> +#define CDEV_NAME(sysdev) (strchr((sysdev)->kobj.name, '!') + 1)
>> +
>> +/* Allow it to be accessed from cdev. */
>> +static void xleaf_devnode_allowed(struct platform_device *pdev)
>> +{
>> + struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
>> +
>> + /* Allow new opens. */
>> + mutex_lock(&pdata->xsp_devnode_lock);
>> + pdata->xsp_devnode_online = true;
>> + mutex_unlock(&pdata->xsp_devnode_lock);
>> +}
>> +
>> +/* Turn off access from cdev and wait for all existing user to go away. */
>> +static int xleaf_devnode_disallowed(struct platform_device *pdev)
>> +{
>> + int ret = 0;
>> + struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
>> +
>> + mutex_lock(&pdata->xsp_devnode_lock);
>> +
>> + /* Prevent new opens. */
>> + pdata->xsp_devnode_online = false;
>> + /* Wait for existing user to close. */
>> + while (!ret && pdata->xsp_devnode_ref) {
>> + int rc;
>> +
>> + mutex_unlock(&pdata->xsp_devnode_lock);
>> + rc = wait_for_completion_killable(&pdata->xsp_devnode_comp);
>> + mutex_lock(&pdata->xsp_devnode_lock);
>> +
>> + if (rc == -ERESTARTSYS) {
>> + /* Restore online state. */
>> + pdata->xsp_devnode_online = true;
>> + xrt_err(pdev, "%s is in use, ref=%d",
>> + CDEV_NAME(pdata->xsp_sysdev),
>> + pdata->xsp_devnode_ref);
>> + ret = -EBUSY;
>> + }
>> + }
>> +
>> + mutex_unlock(&pdata->xsp_devnode_lock);
>> +
>> + return ret;
>> +}
>> +
>> +static struct platform_device *
>> +__xleaf_devnode_open(struct inode *inode, bool excl)
>> +{
>> + struct xrt_subdev_platdata *pdata = INODE2PDATA(inode);
>> + struct platform_device *pdev = INODE2PDEV(inode);
>> + bool opened = false;
>> +
>> + mutex_lock(&pdata->xsp_devnode_lock);
>> +
>> + if (pdata->xsp_devnode_online) {
>> + if (excl && pdata->xsp_devnode_ref) {
>> + xrt_err(pdev, "%s has already been opened exclusively",
>> + CDEV_NAME(pdata->xsp_sysdev));
>> + } else if (!excl && pdata->xsp_devnode_excl) {
>> + xrt_err(pdev, "%s has been opened exclusively",
>> + CDEV_NAME(pdata->xsp_sysdev));
>> + } else {
>> + pdata->xsp_devnode_ref++;
>> + pdata->xsp_devnode_excl = excl;
>> + opened = true;
>> + xrt_info(pdev, "opened %s, ref=%d",
>> + CDEV_NAME(pdata->xsp_sysdev),
>> + pdata->xsp_devnode_ref);
>> + }
>> + } else {
>> + xrt_err(pdev, "%s is offline", CDEV_NAME(pdata->xsp_sysdev));
>> + }
>> +
>> + mutex_unlock(&pdata->xsp_devnode_lock);
>> +
>> + pdev = opened ? pdev : NULL;
>> + return pdev;
>> +}
>> +
>> +struct platform_device *
>> +xleaf_devnode_open_excl(struct inode *inode)
>> +{
>> + return __xleaf_devnode_open(inode, true);
>> +}
>> +
>> +struct platform_device *
>> +xleaf_devnode_open(struct inode *inode)
>> +{
>> + return __xleaf_devnode_open(inode, false);
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_devnode_open);
> generally
>
> exported systems should have their decl's in include/linux/fpga/
>
> These are in drivers/fpga/xrt/include/xleaf.h

But, our exported symbols are only meant to be used inside our drivers
(between two KOs: xmgmt.ko and xrt-lib.ko). They should not be included
and used by other parts of Linux.

> as exported, they should have a better than average prefix.
>
> maybe 'xrt_fpga_'

Since they are really private symbols (exported only because we have two
KOs), I prefer the existing pre-fix so that it is consistent with other
functions in our driver. They should not be used by other codes than our
own driver.

>> +
>> +void xleaf_devnode_close(struct inode *inode)
>> +{
>> + struct xrt_subdev_platdata *pdata = INODE2PDATA(inode);
>> + struct platform_device *pdev = INODE2PDEV(inode);
>> + bool notify = false;
>> +
>> + mutex_lock(&pdata->xsp_devnode_lock);
>> +
>> + pdata->xsp_devnode_ref--;
> check before dec ? or at least warn if ref is already 0

Will add a warning here.

>> + if (pdata->xsp_devnode_ref == 0) {
>> + pdata->xsp_devnode_excl = false;
>> + notify = true;
>> + }
>> + if (notify) {
>> + xrt_info(pdev, "closed %s, ref=%d",
>> + CDEV_NAME(pdata->xsp_sysdev), pdata->xsp_devnode_ref);
>> + } else {
>> + xrt_info(pdev, "closed %s, notifying waiter",
>> + CDEV_NAME(pdata->xsp_sysdev));
>> + }
>> +
>> + mutex_unlock(&pdata->xsp_devnode_lock);
>> +
>> + if (notify)
>> + complete(&pdata->xsp_devnode_comp);
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_devnode_close);
>> +
>> +static inline enum xrt_subdev_file_mode
>> +devnode_mode(struct xrt_subdev_drvdata *drvdata)
>> +{
>> + return drvdata->xsd_file_ops.xsf_mode;
>> +}
>> +
>> +int xleaf_devnode_create(struct platform_device *pdev, const char *file_name,
>> + const char *inst_name)
>> +{
>> + struct xrt_subdev_drvdata *drvdata = DEV_DRVDATA(pdev);
>> + struct xrt_subdev_file_ops *fops = &drvdata->xsd_file_ops;
>> + struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
>> + struct cdev *cdevp;
>> + struct device *sysdev;
>> + int ret = 0;
>> + char fname[256];
> will a /dev/xfpga* created for ever leaf device ?
>
> do they all really need /dev/ support ?

No, most of them do not need one. The device node is only created for
some of them.

>> +
>> + mutex_init(&pdata->xsp_devnode_lock);
>> + init_completion(&pdata->xsp_devnode_comp);
>> +
>> + cdevp = &DEV_PDATA(pdev)->xsp_cdev;
> no cdev_alloc ?

We did a cdev_init() here as below. Does it not work?

>> + cdev_init(cdevp, &fops->xsf_ops);
>> + cdevp->owner = fops->xsf_ops.owner;
>> + cdevp->dev = MKDEV(MAJOR(fops->xsf_dev_t), pdev->id);
>> +
>> + /*
>> + * Set pdev as parent of cdev so that when pdev (and its platform
>> + * data) will not be freed when cdev is not freed.
>> + */
>> + cdev_set_parent(cdevp, &DEV(pdev)->kobj);
>> +
>> + ret = cdev_add(cdevp, cdevp->dev, 1);
>> + if (ret) {
>> + xrt_err(pdev, "failed to add cdev: %d", ret);
>> + goto failed;
>> + }
>> + if (!file_name)
>> + file_name = pdev->name;
>> + if (!inst_name) {
>> + if (devnode_mode(drvdata) == XRT_SUBDEV_FILE_MULTI_INST) {
>> + snprintf(fname, sizeof(fname), "%s/%s/%s.%u",
>> + XRT_CDEV_DIR, DEV_PDATA(pdev)->xsp_root_name,
>> + file_name, pdev->id);
>> + } else {
>> + snprintf(fname, sizeof(fname), "%s/%s/%s",
>> + XRT_CDEV_DIR, DEV_PDATA(pdev)->xsp_root_name,
>> + file_name);
>> + }
>> + } else {
>> + snprintf(fname, sizeof(fname), "%s/%s/%s.%s", XRT_CDEV_DIR,
>> + DEV_PDATA(pdev)->xsp_root_name, file_name, inst_name);
>> + }
>> + sysdev = device_create(xrt_class, NULL, cdevp->dev, NULL, "%s", fname);
>> + if (IS_ERR(sysdev)) {
>> + ret = PTR_ERR(sysdev);
>> + xrt_err(pdev, "failed to create device node: %d", ret);
>> + goto failed;
> this calls device_destroy, but the create call failed, so is this needed ?

Will fix.

>> + }
>> + pdata->xsp_sysdev = sysdev;
>> +
>> + xleaf_devnode_allowed(pdev);
>> +
>> + xrt_info(pdev, "created (%d, %d): /dev/%s",
>> + MAJOR(cdevp->dev), pdev->id, fname);
>> + return 0;
>> +
>> +failed:
>> + device_destroy(xrt_class, cdevp->dev);
>> + cdev_del(cdevp);
>> + cdevp->owner = NULL;
>> + return ret;
>> +}
>> +
>> +int xleaf_devnode_destroy(struct platform_device *pdev)
>> +{
>> + struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
>> + struct cdev *cdevp = &pdata->xsp_cdev;
>> + dev_t dev = cdevp->dev;
>> + int rc;
>> +
>> + rc = xleaf_devnode_disallowed(pdev);
>> + if (rc)
>> + return rc;
> This return is not checked by xrt_subdev_destroy

I will add a check and warning in xrt_subdev_destroy().

>> +
>> + xrt_info(pdev, "removed (%d, %d): /dev/%s/%s", MAJOR(dev), MINOR(dev),
>> + XRT_CDEV_DIR, CDEV_NAME(pdata->xsp_sysdev));
>> + device_destroy(xrt_class, cdevp->dev);
>> + pdata->xsp_sysdev = NULL;
>> + cdev_del(cdevp);
>> + return 0;
>> +}
>> diff --git a/drivers/fpga/xrt/lib/subdev.c b/drivers/fpga/xrt/lib/subdev.c
>> new file mode 100644
>> index 000000000000..73552c549bdb
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/lib/subdev.c
>> @@ -0,0 +1,871 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Xilinx Alveo FPGA device helper functions
>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + * Cheng Zhen<maxz@xilinx.com>
>> + */
>> +
>> +#include <linux/platform_device.h>
>> +#include <linux/pci.h>
>> +#include <linux/vmalloc.h>
>> +#include "xleaf.h"
>> +#include "subdev_pool.h"
>> +#include "main.h"
>> +#include "metadata.h"
>> +
>> +#define DEV_IS_PCI(dev) ((dev)->bus == &pci_bus_type)
>> +static inline struct device *find_root(struct platform_device *pdev)
>> +{
>> + struct device *d = DEV(pdev);
>> +
>> + while (!DEV_IS_PCI(d))
>> + d = d->parent;
> Shouldn't the root have no parent ?
>
> Could then check if d->parent == NULL instead of bus type

The root is a PCIE device driver whose struct device is managed by PCIE
driver framework. I don't think I can assume d->parent is NULL, right?

>> + return d;
>> +}
>> +
>> +/*
>> + * It represents a holder of a subdev. One holder can repeatedly hold a subdev
>> + * as long as there is a unhold corresponding to a hold.
>> + */
>> +struct xrt_subdev_holder {
>> + struct list_head xsh_holder_list;
>> + struct device *xsh_holder;
>> + int xsh_count;
>> + struct kref xsh_kref;
> general, i see this in struct xrt_subdev
>
> guessing 'xsh' is xrt subdev holder.
>
> why is this prefix needed for the elements ? consider removing it.

It's good to have unique element name so that it's easier to grep the
reference in the code. I'd like to keep them.

>> +};
>> +
>> +/*
>> + * It represents a specific instance of platform driver for a subdev, which
>> + * provides services to its clients (another subdev driver or root driver).
>> + */
>> +struct xrt_subdev {
>> + struct list_head xs_dev_list;
>> + struct list_head xs_holder_list;
>> + enum xrt_subdev_id xs_id; /* type of subdev */
>> + struct platform_device *xs_pdev; /* a particular subdev inst */
>> + struct completion xs_holder_comp;
>> +};
>> +
>> +static struct xrt_subdev *xrt_subdev_alloc(void)
>> +{
>> + struct xrt_subdev *sdev = vzalloc(sizeof(*sdev));
> similar kzalloc as another patch.

Sure.

>> +
>> + if (!sdev)
>> + return NULL;
>> +
>> + INIT_LIST_HEAD(&sdev->xs_dev_list);
>> + INIT_LIST_HEAD(&sdev->xs_holder_list);
>> + init_completion(&sdev->xs_holder_comp);
>> + return sdev;
>> +}
>> +
>> +static void xrt_subdev_free(struct xrt_subdev *sdev)
>> +{
>> + vfree(sdev);
>> +}
>> +
>> +int xrt_subdev_root_request(struct platform_device *self, u32 cmd, void *arg)
>> +{
>> + struct device *dev = DEV(self);
>> + struct xrt_subdev_platdata *pdata = DEV_PDATA(self);
>> +
>> + return (*pdata->xsp_root_cb)(dev->parent, pdata->xsp_root_cb_arg, cmd, arg);
> xrt_subdev_create does not check if pcb is valid. is a null is passed in, it will crash.
>
> there should at least be a warn or -INVALID returned there

This should not happen. I will add a warning here.

>> +}
>> +
>> +/*
>> + * Subdev common sysfs nodes.
>> + */
>> +static ssize_t holders_show(struct device *dev, struct device_attribute *attr, char *buf)
>> +{
>> + ssize_t len;
>> + struct platform_device *pdev = to_platform_device(dev);
>> + struct xrt_root_ioctl_get_holders holders = { pdev, buf, 1024 };
> is 1024 a guess ?

Yes, something big enough.

>> +
>> + len = xrt_subdev_root_request(pdev, XRT_ROOT_GET_LEAF_HOLDERS, &holders);
> take a closer look at xrt_subdev_get_holders() it stops after it goes past len.

Yes, this is for debug only, so it's OK to truncate the holder list here.

>> + if (len >= holders.xpigh_holder_buf_len)
>> + return len;
>> + buf[len] = '\n';
>> + return len + 1;
>> +}
>> +static DEVICE_ATTR_RO(holders);
>> +
>> +static struct attribute *xrt_subdev_attrs[] = {
>> + &dev_attr_holders.attr,
>> + NULL,
>> +};
>> +
>> +static ssize_t metadata_output(struct file *filp, struct kobject *kobj,
>> + struct bin_attribute *attr, char *buf, loff_t off, size_t count)
>> +{
>> + struct device *dev = kobj_to_dev(kobj);
>> + struct platform_device *pdev = to_platform_device(dev);
>> + struct xrt_subdev_platdata *pdata = DEV_PDATA(pdev);
>> + unsigned char *blob;
>> + unsigned long size;
>> + ssize_t ret = 0;
>> +
>> + blob = pdata->xsp_dtb;
>> + size = xrt_md_size(dev, blob);
>> + if (size == XRT_MD_INVALID_LENGTH) {
>> + ret = -EINVAL;
>> + goto failed;
>> + }
>> +
>> + if (off >= size)
>> + goto failed;
> silently failed because ret = 0 ?

It's fine. This is just for debugging.

>> +
>> + if (off + count > size)
>> + count = size - off;
> truncating is ok ?

Yes, this is just for debugging.

>> + memcpy(buf, blob + off, count);
>> +
>> + ret = count;
>> +failed:
>> + return ret;
>> +}
>> +
>> +static struct bin_attribute meta_data_attr = {
>> + .attr = {
>> + .name = "metadata",
>> + .mode = 0400
>> + },
>> + .read = metadata_output,
>> + .size = 0
>> +};
>> +
>> +static struct bin_attribute *xrt_subdev_bin_attrs[] = {
>> + &meta_data_attr,
> is giving the average user access to the meta data a good idea ?
>
> this seems like a developer only need.

Yes, this is for developer only. We do not want to give normal user
access to it. Hence we set .mode to 0400.

>> + NULL,
>> +};
>> +
>> +static const struct attribute_group xrt_subdev_attrgroup = {
>> + .attrs = xrt_subdev_attrs,
>> + .bin_attrs = xrt_subdev_bin_attrs,
>> +};
>> +
>> +/*
>> + * Given the device metadata, parse it to get IO ranges and construct
>> + * resource array.
>> + */
>> +static int
>> +xrt_subdev_getres(struct device *parent, enum xrt_subdev_id id,
>> + char *dtb, struct resource **res, int *res_num)
>> +{
>> + struct xrt_subdev_platdata *pdata;
>> + struct resource *pci_res = NULL;
>> + const u64 *bar_range;
>> + const u32 *bar_idx;
>> + char *ep_name = NULL, *regmap = NULL;
>> + uint bar;
>> + int count1 = 0, count2 = 0, ret;
>> +
>> + if (!dtb)
>> + return -EINVAL;
>> +
>> + pdata = DEV_PDATA(to_platform_device(parent));
>> +
>> + /* go through metadata and count endpoints in it */
>> + for (xrt_md_get_next_endpoint(parent, dtb, NULL, NULL, &ep_name, &regmap); ep_name;
> Ugly.
>
> Can you preprocess the dtb into a list of end points ?

Not sure I follow? But you still need to iterate the list even if you
preprocess it, right? Not sure which part is ugly?

>> + xrt_md_get_next_endpoint(parent, dtb, ep_name, regmap, &ep_name, &regmap)) {
>> + ret = xrt_md_get_prop(parent, dtb, ep_name, regmap,
>> + XRT_MD_PROP_IO_OFFSET, (const void **)&bar_range, NULL);
>> + if (!ret)
>> + count1++;
>> + }
>> + if (!count1)
>> + return 0;
>> +
>> + /* allocate resource array for all endpoints been found in metadata */
>> + *res = vzalloc(sizeof(**res) * count1);
>> +
>> + /* go through all endpoints again and get IO range for each endpoint */
>> + for (xrt_md_get_next_endpoint(parent, dtb, NULL, NULL, &ep_name, &regmap); ep_name;
>> + xrt_md_get_next_endpoint(parent, dtb, ep_name, regmap, &ep_name, &regmap)) {
>> + ret = xrt_md_get_prop(parent, dtb, ep_name, regmap,
>> + XRT_MD_PROP_IO_OFFSET, (const void **)&bar_range, NULL);
>> + if (ret)
>> + continue;
>> + xrt_md_get_prop(parent, dtb, ep_name, regmap,
>> + XRT_MD_PROP_BAR_IDX, (const void **)&bar_idx, NULL);
> bar can fail, but bar idx can not.
>
> should add an assert here

When there is no bar idx, we use default value 0. So, bar idx can also fail.

>> + bar = bar_idx ? be32_to_cpu(*bar_idx) : 0;
>> + xleaf_get_barres(to_platform_device(parent), &pci_res, bar);
>> + (*res)[count2].start = pci_res->start +
>> + be64_to_cpu(bar_range[0]);
>> + (*res)[count2].end = pci_res->start +
>> + be64_to_cpu(bar_range[0]) +
>> + be64_to_cpu(bar_range[1]) - 1;
>> + (*res)[count2].flags = IORESOURCE_MEM;
> any irqs need handling?

Currently, we do not have irqs to handle.

>> + /* check if there is conflicted resource */
>> + ret = request_resource(pci_res, *res + count2);
>> + if (ret) {
>> + dev_err(parent, "Conflict resource %pR\n", *res + count2);
>> + vfree(*res);
>> + *res_num = 0;
>> + *res = NULL;
>> + return ret;
>> + }
>> + release_resource(*res + count2);
>> +
>> + (*res)[count2].parent = pci_res;
>> +
>> + xrt_md_find_endpoint(parent, pdata->xsp_dtb, ep_name,
>> + regmap, &(*res)[count2].name);
>> +
>> + count2++;
>> + }
>> +
>> + WARN_ON(count1 != count2);
>> + *res_num = count2;
>> +
>> + return 0;
>> +}
>> +
>> +static inline enum xrt_subdev_file_mode
>> +xleaf_devnode_mode(struct xrt_subdev_drvdata *drvdata)
>> +{
>> + return drvdata->xsd_file_ops.xsf_mode;
>> +}
>> +
>> +static bool xrt_subdev_cdev_auto_creation(struct platform_device *pdev)
>> +{
>> + struct xrt_subdev_drvdata *drvdata = DEV_DRVDATA(pdev);
>> +
>> + if (!drvdata)
>> + return false;
>> +
>> + return xleaf_devnode_enabled(drvdata) &&
>> + (xleaf_devnode_mode(drvdata) == XRT_SUBDEV_FILE_DEFAULT ||
>> + (xleaf_devnode_mode(drvdata) == XRT_SUBDEV_FILE_MULTI_INST));
> This is complicated to check, split into checking the call and then checking its side effects.

Sure.

>> +}
>> +
>> +static struct xrt_subdev *
>> +xrt_subdev_create(struct device *parent, enum xrt_subdev_id id,
>> + xrt_subdev_root_cb_t pcb, void *pcb_arg, char *dtb)
>> +{
>> + struct xrt_subdev *sdev = NULL;
>> + struct platform_device *pdev = NULL;
>> + struct xrt_subdev_platdata *pdata = NULL;
>> + unsigned long dtb_len = 0;
>> + size_t pdata_sz;
>> + int inst = PLATFORM_DEVID_NONE;
>> + struct resource *res = NULL;
>> + int res_num = 0;
>> +
>> + sdev = xrt_subdev_alloc();
>> + if (!sdev) {
>> + dev_err(parent, "failed to alloc subdev for ID %d", id);
>> + goto fail;
>> + }
>> + sdev->xs_id = id;
>> +
>> + if (dtb) {
>> + xrt_md_pack(parent, dtb);
>> + dtb_len = xrt_md_size(parent, dtb);
>> + if (dtb_len == XRT_MD_INVALID_LENGTH) {
>> + dev_err(parent, "invalid metadata len %ld", dtb_len);
>> + goto fail;
>> + }
>> + }
>> + pdata_sz = sizeof(struct xrt_subdev_platdata) + dtb_len - 1;
> -1 ?
>
> if dtb_len == 0, pdata_sz be too small.

Will fix.

>> +
>> + /* Prepare platform data passed to subdev. */
>> + pdata = vzalloc(pdata_sz);
>> + if (!pdata)
>> + goto fail;
>> +
>> + pdata->xsp_root_cb = pcb;
>> + pdata->xsp_root_cb_arg = pcb_arg;
>> + memcpy(pdata->xsp_dtb, dtb, dtb_len);
>> + if (id == XRT_SUBDEV_GRP) {
>> + /* Group can only be created by root driver. */
>> + pdata->xsp_root_name = dev_name(parent);
>> + } else {
>> + struct platform_device *grp = to_platform_device(parent);
>> + /* Leaf can only be created by group driver. */
>> + WARN_ON(strcmp(xrt_drv_name(XRT_SUBDEV_GRP), platform_get_device_id(grp)->name));
>> + pdata->xsp_root_name = DEV_PDATA(grp)->xsp_root_name;
>> + }
>> +
>> + /* Obtain dev instance number. */
>> + inst = xrt_drv_get_instance(id);
>> + if (inst < 0) {
>> + dev_err(parent, "failed to obtain instance: %d", inst);
>> + goto fail;
>> + }
>> +
>> + /* Create subdev. */
>> + if (id == XRT_SUBDEV_GRP) {
>> + pdev = platform_device_register_data(parent, xrt_drv_name(XRT_SUBDEV_GRP),
>> + inst, pdata, pdata_sz);
>> + } else {
>> + int rc = xrt_subdev_getres(parent, id, dtb, &res, &res_num);
>> +
>> + if (rc) {
>> + dev_err(parent, "failed to get resource for %s.%d: %d",
>> + xrt_drv_name(id), inst, rc);
>> + goto fail;
>> + }
>> + pdev = platform_device_register_resndata(parent, xrt_drv_name(id),
>> + inst, res, res_num, pdata, pdata_sz);
>> + vfree(res);
>> + }
> a small optimization
>
> platform_device_register_data is a wrapper to platform_device_register_resndata.
>
> with initial values for res, res_num, just one call need to be made.

Sure.

>> + if (IS_ERR(pdev)) {
>> + dev_err(parent, "failed to create subdev for %s inst %d: %ld",
>> + xrt_drv_name(id), inst, PTR_ERR(pdev));
>> + goto fail;
>> + }
>> + sdev->xs_pdev = pdev;
>> +
>> + if (device_attach(DEV(pdev)) != 1) {
>> + xrt_err(pdev, "failed to attach");
>> + goto fail;
>> + }
>> +
>> + if (sysfs_create_group(&DEV(pdev)->kobj, &xrt_subdev_attrgroup))
>> + xrt_err(pdev, "failed to create sysfs group");
> no failure ?

Not treated as fatal, so just issue a error message.

>> +
>> + /*
>> + * Create sysfs sym link under root for leaves
>> + * under random groups for easy access to them.
>> + */
>> + if (id != XRT_SUBDEV_GRP) {
>> + if (sysfs_create_link(&find_root(pdev)->kobj,
>> + &DEV(pdev)->kobj, dev_name(DEV(pdev)))) {
>> + xrt_err(pdev, "failed to create sysfs link");
>> + }
>> + }
>> +
>> + /* All done, ready to handle req thru cdev. */
>> + if (xrt_subdev_cdev_auto_creation(pdev))
>> + xleaf_devnode_create(pdev, DEV_DRVDATA(pdev)->xsd_file_ops.xsf_dev_name, NULL);
>> +
>> + vfree(pdata);
>> + return sdev;
>> +
>> +fail:
> Instead of adding checks in the error handling block, add more specific labels and gotos.
>
> I think i have noticed this before, so apply this advice generally.

It seems that it's easier to do the check than adding a whole bunch of
labels, so that you can just jump to the same label for error handling
without worrying about jumping to the wrong label? And it is also
possible that some of the error handling may have been done in the
middle of the function, so you don't need to redo it in the end. But
adding labels only works for incremental error handlings.

>> + vfree(pdata);
>> + if (sdev && !IS_ERR_OR_NULL(sdev->xs_pdev))
>> + platform_device_unregister(sdev->xs_pdev);
>> + if (inst >= 0)
>> + xrt_drv_put_instance(id, inst);
>> + xrt_subdev_free(sdev);
>> + return NULL;
>> +}
>> +
>> +static void xrt_subdev_destroy(struct xrt_subdev *sdev)
>> +{
>> + struct platform_device *pdev = sdev->xs_pdev;
>> + int inst = pdev->id;
>> + struct device *dev = DEV(pdev);
>> +
>> + /* Take down the device node */
>> + if (xrt_subdev_cdev_auto_creation(pdev))
>> + xleaf_devnode_destroy(pdev);
>> + if (sdev->xs_id != XRT_SUBDEV_GRP)
>> + sysfs_remove_link(&find_root(pdev)->kobj, dev_name(dev));
>> + sysfs_remove_group(&dev->kobj, &xrt_subdev_attrgroup);
>> + platform_device_unregister(pdev);
>> + xrt_drv_put_instance(sdev->xs_id, inst);
>> + xrt_subdev_free(sdev);
>> +}
>> +
>> +struct platform_device *
>> +xleaf_get_leaf(struct platform_device *pdev, xrt_subdev_match_t match_cb, void *match_arg)
>> +{
>> + int rc;
>> + struct xrt_root_ioctl_get_leaf get_leaf = {
>> + pdev, match_cb, match_arg, };
>> +
>> + rc = xrt_subdev_root_request(pdev, XRT_ROOT_GET_LEAF, &get_leaf);
>> + if (rc)
>> + return NULL;
>> + return get_leaf.xpigl_leaf;
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_get_leaf);
>> +
>> +bool xleaf_has_endpoint(struct platform_device *pdev, const char *endpoint_name)
>> +{
>> + struct resource *res;
>> + int i;
> whitespace

Sure.

>> +
>> + for (i = 0, res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + res;
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, ++i)) {
> Do not inc i inside the call, do it at the bottom of the loop

Sure.

>> + if (!strncmp(res->name, endpoint_name, strlen(res->name) + 1))
> shouldn't you also check the strlen matches ?

We compare strlen + 1, so the null terminate will be compared, too.

>> + return true;
>> + }
>> +
>> + return false;
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_has_endpoint);
>> +
>> +int xleaf_put_leaf(struct platform_device *pdev, struct platform_device *leaf)
>> +{
>> + struct xrt_root_ioctl_put_leaf put_leaf = { pdev, leaf };
>> +
>> + return xrt_subdev_root_request(pdev, XRT_ROOT_PUT_LEAF, &put_leaf);
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_put_leaf);
>> +
>> +int xleaf_create_group(struct platform_device *pdev, char *dtb)
>> +{
>> + return xrt_subdev_root_request(pdev, XRT_ROOT_CREATE_GROUP, dtb);
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_create_group);
>> +
>> +int xleaf_destroy_group(struct platform_device *pdev, int instance)
>> +{
>> + return xrt_subdev_root_request(pdev, XRT_ROOT_REMOVE_GROUP, (void *)(uintptr_t)instance);
> Instead of these clunky casts, why not make the type of the args void *
>
> and leave it to the handler to cast.
>
> this would unify the signature of these functions somewhat.

The type of arg for xrt_subdev_root_request() is already void *. But I
can't just pass instance as a int to the void *, so have to cast here.

>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_destroy_group);
>> +
>> +int xleaf_wait_for_group_bringup(struct platform_device *pdev)
>> +{
>> + return xrt_subdev_root_request(pdev, XRT_ROOT_WAIT_GROUP_BRINGUP, NULL);
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_wait_for_group_bringup);
>> +
>> +static ssize_t
>> +xrt_subdev_get_holders(struct xrt_subdev *sdev, char *buf, size_t len)
>> +{
>> + const struct list_head *ptr;
>> + struct xrt_subdev_holder *h;
>> + ssize_t n = 0;
>> +
>> + list_for_each(ptr, &sdev->xs_holder_list) {
>> + h = list_entry(ptr, struct xrt_subdev_holder, xsh_holder_list);
>> + n += snprintf(buf + n, len - n, "%s:%d ",
>> + dev_name(h->xsh_holder), kref_read(&h->xsh_kref));
>> + if (n >= (len - 1))
> This is the overrun i mentioned above.

Truncation is fine.

>> + break;
>> + }
>> + return n;
>> +}
>> +
>> +void xrt_subdev_pool_init(struct device *dev, struct xrt_subdev_pool *spool)
>> +{
>> + INIT_LIST_HEAD(&spool->xsp_dev_list);
>> + spool->xsp_owner = dev;
>> + mutex_init(&spool->xsp_lock);
>> + spool->xsp_closing = false;
>> +}
>> +
>> +static void xrt_subdev_free_holder(struct xrt_subdev_holder *holder)
>> +{
>> + list_del(&holder->xsh_holder_list);
>> + vfree(holder);
>> +}
>> +
>> +static void xrt_subdev_pool_wait_for_holders(struct xrt_subdev_pool *spool, struct xrt_subdev *sdev)
>> +{
>> + const struct list_head *ptr, *next;
>> + char holders[128];
>> + struct xrt_subdev_holder *holder;
>> + struct mutex *lk = &spool->xsp_lock;
>> +
>> + WARN_ON(!mutex_is_locked(lk));
>> +
>> + while (!list_empty(&sdev->xs_holder_list)) {
>> + int rc;
>> +
>> + /* It's most likely a bug if we ever enters this loop. */
>> + xrt_subdev_get_holders(sdev, holders, sizeof(holders));
> will overrun, error not reported.

It's ok, just for debugging.

>> + xrt_err(sdev->xs_pdev, "awaits holders: %s", holders);
>> + mutex_unlock(lk);
>> + rc = wait_for_completion_killable(&sdev->xs_holder_comp);
>> + mutex_lock(lk);
>> + if (rc == -ERESTARTSYS) {
>> + xrt_err(sdev->xs_pdev, "give up on waiting for holders, clean up now");
>> + list_for_each_safe(ptr, next, &sdev->xs_holder_list) {
>> + holder = list_entry(ptr, struct xrt_subdev_holder, xsh_holder_list);
>> + xrt_subdev_free_holder(holder);
>> + }
>> + }
>> + }
>> +}
>> +
>> +void xrt_subdev_pool_fini(struct xrt_subdev_pool *spool)
>> +{
>> + struct list_head *dl = &spool->xsp_dev_list;
>> + struct mutex *lk = &spool->xsp_lock;
>> +
>> + mutex_lock(lk);
>> +
> i am wondering about the locking here.
>
> xsp_closing is only set to true in this function.
>
> the unlocking then relocking in the loop is strange, why do you need to do this ?

Right, I don't need to hold the lock while going through the list and
destroy each subdev. Setting xsp_closing to true will prevent others
from messing up with the list already. I will fix this.

>> + if (spool->xsp_closing) {
>> + mutex_unlock(lk);
>> + return;
>> + }
>> +
>> + spool->xsp_closing = true;
>> + /* Remove subdev in the reverse order of added. */
>> + while (!list_empty(dl)) {
>> + struct xrt_subdev *sdev = list_first_entry(dl, struct xrt_subdev, xs_dev_list);
>> +
>> + xrt_subdev_pool_wait_for_holders(spool, sdev);
>> + list_del(&sdev->xs_dev_list);
>> + mutex_unlock(lk);
>> + xrt_subdev_destroy(sdev);
>> + mutex_lock(lk);
>> + }
>> +
>> + mutex_unlock(lk);
>> +}
>> +
>> +static struct xrt_subdev_holder *xrt_subdev_find_holder(struct xrt_subdev *sdev,
>> + struct device *holder_dev)
>> +{
>> + struct list_head *hl = &sdev->xs_holder_list;
>> + struct xrt_subdev_holder *holder;
>> + const struct list_head *ptr;
>> +
>> + list_for_each(ptr, hl) {
>> + holder = list_entry(ptr, struct xrt_subdev_holder, xsh_holder_list);
>> + if (holder->xsh_holder == holder_dev)
>> + return holder;
>> + }
>> + return NULL;
>> +}
>> +
>> +static int xrt_subdev_hold(struct xrt_subdev *sdev, struct device *holder_dev)
>> +{
>> + struct xrt_subdev_holder *holder = xrt_subdev_find_holder(sdev, holder_dev);
>> + struct list_head *hl = &sdev->xs_holder_list;
>> +
>> + if (!holder) {
>> + holder = vzalloc(sizeof(*holder));
>> + if (!holder)
>> + return -ENOMEM;
>> + holder->xsh_holder = holder_dev;
>> + kref_init(&holder->xsh_kref);
>> + list_add_tail(&holder->xsh_holder_list, hl);
>> + } else {
>> + kref_get(&holder->xsh_kref);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static void xrt_subdev_free_holder_kref(struct kref *kref)
>> +{
>> + struct xrt_subdev_holder *holder = container_of(kref, struct xrt_subdev_holder, xsh_kref);
>> +
>> + xrt_subdev_free_holder(holder);
>> +}
>> +
>> +static int
>> +xrt_subdev_release(struct xrt_subdev *sdev, struct device *holder_dev)
>> +{
>> + struct xrt_subdev_holder *holder = xrt_subdev_find_holder(sdev, holder_dev);
>> + struct list_head *hl = &sdev->xs_holder_list;
>> +
>> + if (!holder) {
>> + dev_err(holder_dev, "can't release, %s did not hold %s",
>> + dev_name(holder_dev), dev_name(DEV(sdev->xs_pdev)));
>> + return -EINVAL;
>> + }
>> + kref_put(&holder->xsh_kref, xrt_subdev_free_holder_kref);
>> +
>> + /* kref_put above may remove holder from list. */
>> + if (list_empty(hl))
>> + complete(&sdev->xs_holder_comp);
>> + return 0;
>> +}
>> +
>> +int xrt_subdev_pool_add(struct xrt_subdev_pool *spool, enum xrt_subdev_id id,
>> + xrt_subdev_root_cb_t pcb, void *pcb_arg, char *dtb)
>> +{
>> + struct mutex *lk = &spool->xsp_lock;
>> + struct list_head *dl = &spool->xsp_dev_list;
>> + struct xrt_subdev *sdev;
>> + int ret = 0;
>> +
>> + sdev = xrt_subdev_create(spool->xsp_owner, id, pcb, pcb_arg, dtb);
>> + if (sdev) {
>> + mutex_lock(lk);
>> + if (spool->xsp_closing) {
>> + /* No new subdev when pool is going away. */
>> + xrt_err(sdev->xs_pdev, "pool is closing");
>> + ret = -ENODEV;
>> + } else {
>> + list_add(&sdev->xs_dev_list, dl);
>> + }
>> + mutex_unlock(lk);
>> + if (ret)
>> + xrt_subdev_destroy(sdev);
>> + } else {
>> + ret = -EINVAL;
>> + }
>> +
>> + ret = ret ? ret : sdev->xs_pdev->id;
>> + return ret;
>> +}
>> +
>> +int xrt_subdev_pool_del(struct xrt_subdev_pool *spool, enum xrt_subdev_id id, int instance)
>> +{
>> + const struct list_head *ptr;
>> + struct mutex *lk = &spool->xsp_lock;
>> + struct list_head *dl = &spool->xsp_dev_list;
>> + struct xrt_subdev *sdev;
>> + int ret = -ENOENT;
>> +
>> + mutex_lock(lk);
>> + list_for_each(ptr, dl) {
>> + sdev = list_entry(ptr, struct xrt_subdev, xs_dev_list);
>> + if (sdev->xs_id != id || sdev->xs_pdev->id != instance)
>> + continue;
>> + xrt_subdev_pool_wait_for_holders(spool, sdev);
>> + list_del(&sdev->xs_dev_list);
>> + ret = 0;
>> + break;
>> + }
>> + mutex_unlock(lk);
>> + if (ret)
>> + return ret;
>> +
>> + xrt_subdev_destroy(sdev);
>> + return 0;
>> +}
>> +
>> +static int xrt_subdev_pool_get_impl(struct xrt_subdev_pool *spool, xrt_subdev_match_t match,
>> + void *arg, struct device *holder_dev, struct xrt_subdev **sdevp)
>> +{
>> + const struct list_head *ptr;
>> + struct mutex *lk = &spool->xsp_lock;
>> + struct list_head *dl = &spool->xsp_dev_list;
>> + struct xrt_subdev *sdev = NULL;
>> + int ret = -ENOENT;
>> +
>> + mutex_lock(lk);
>> +
>> + if (match == XRT_SUBDEV_MATCH_PREV) {
>> + struct platform_device *pdev = (struct platform_device *)arg;
>> + struct xrt_subdev *d = NULL;
>> +
>> + if (!pdev) {
>> + sdev = list_empty(dl) ? NULL :
>> + list_last_entry(dl, struct xrt_subdev, xs_dev_list);
>> + } else {
>> + list_for_each(ptr, dl) {
>> + d = list_entry(ptr, struct xrt_subdev, xs_dev_list);
>> + if (d->xs_pdev != pdev)
>> + continue;
>> + if (!list_is_first(ptr, dl))
>> + sdev = list_prev_entry(d, xs_dev_list);
>> + break;
>> + }
>> + }
>> + } else if (match == XRT_SUBDEV_MATCH_NEXT) {
>> + struct platform_device *pdev = (struct platform_device *)arg;
>> + struct xrt_subdev *d = NULL;
>> +
>> + if (!pdev) {
>> + sdev = list_first_entry_or_null(dl, struct xrt_subdev, xs_dev_list);
>> + } else {
>> + list_for_each(ptr, dl) {
>> + d = list_entry(ptr, struct xrt_subdev, xs_dev_list);
>> + if (d->xs_pdev != pdev)
>> + continue;
>> + if (!list_is_last(ptr, dl))
>> + sdev = list_next_entry(d, xs_dev_list);
>> + break;
>> + }
>> + }
>> + } else {
>> + list_for_each(ptr, dl) {
>> + struct xrt_subdev *d = NULL;
>> +
>> + d = list_entry(ptr, struct xrt_subdev, xs_dev_list);
>> + if (d && !match(d->xs_id, d->xs_pdev, arg))
>> + continue;
>> + sdev = d;
>> + break;
>> + }
>> + }
> 3 similar blocks of code
>
> This looks like it could be refactored into this else case and minor changes for match_next/prev

Will refactor and keep only one list_for_each() loop.

>> +
>> + if (sdev)
>> + ret = xrt_subdev_hold(sdev, holder_dev);
>> +
>> + mutex_unlock(lk);
>> +
>> + if (!ret)
>> + *sdevp = sdev;
>> + return ret;
>> +}
>> +
>> +int xrt_subdev_pool_get(struct xrt_subdev_pool *spool, xrt_subdev_match_t match, void *arg,
>> + struct device *holder_dev, struct platform_device **pdevp)
>> +{
>> + int rc;
>> + struct xrt_subdev *sdev;
>> +
>> + rc = xrt_subdev_pool_get_impl(spool, match, arg, holder_dev, &sdev);
>> + if (rc) {
>> + if (rc != -ENOENT)
>> + dev_err(holder_dev, "failed to hold device: %d", rc);
>> + return rc;
>> + }
>> +
>> + if (!DEV_IS_PCI(holder_dev)) {
> ! root_dev()

Will add root_dev().

>> + xrt_dbg(to_platform_device(holder_dev), "%s <<==== %s",
>> + dev_name(holder_dev), dev_name(DEV(sdev->xs_pdev)));
>> + }
>> +
>> + *pdevp = sdev->xs_pdev;
>> + return 0;
>> +}
>> +
>> +static int xrt_subdev_pool_put_impl(struct xrt_subdev_pool *spool, struct platform_device *pdev,
>> + struct device *holder_dev)
>> +{
>> + const struct list_head *ptr;
>> + struct mutex *lk = &spool->xsp_lock;
>> + struct list_head *dl = &spool->xsp_dev_list;
>> + struct xrt_subdev *sdev;
>> + int ret = -ENOENT;
>> +
>> + mutex_lock(lk);
>> + list_for_each(ptr, dl) {
>> + sdev = list_entry(ptr, struct xrt_subdev, xs_dev_list);
>> + if (sdev->xs_pdev != pdev)
>> + continue;
> Could this and similar looping be avoided by storing sdev in pdev ?

Not sure which field in struct platform_device can sdev pointer be saved?

>> + ret = xrt_subdev_release(sdev, holder_dev);
>> + break;
>> + }
>> + mutex_unlock(lk);
>> +
>> + return ret;
>> +}
>> +
>> +int xrt_subdev_pool_put(struct xrt_subdev_pool *spool, struct platform_device *pdev,
>> + struct device *holder_dev)
>> +{
>> + int ret = xrt_subdev_pool_put_impl(spool, pdev, holder_dev);
>> +
>> + if (ret)
>> + return ret;
>> +
>> + if (!DEV_IS_PCI(holder_dev)) {
> ! root_dev() or similar.
>
> If you really need to use DEV_IS_PCI, do it only once so when you need to change something you don not have to find all the calls to DEV_IS_PCI.

Will add root_dev() function.

>> + xrt_dbg(to_platform_device(holder_dev), "%s <<==X== %s",
>> + dev_name(holder_dev), dev_name(DEV(pdev)));
>> + }
>> + return 0;
>> +}
>> +
>> +void xrt_subdev_pool_trigger_event(struct xrt_subdev_pool *spool, enum xrt_events e)
>> +{
>> + struct platform_device *tgt = NULL;
>> + struct xrt_subdev *sdev = NULL;
>> + struct xrt_event evt;
>> +
>> + while (!xrt_subdev_pool_get_impl(spool, XRT_SUBDEV_MATCH_NEXT,
>> + tgt, spool->xsp_owner, &sdev)) {
>> + tgt = sdev->xs_pdev;
>> + evt.xe_evt = e;
>> + evt.xe_subdev.xevt_subdev_id = sdev->xs_id;
>> + evt.xe_subdev.xevt_subdev_instance = tgt->id;
>> + xrt_subdev_root_request(tgt, XRT_ROOT_EVENT, &evt);
>> + xrt_subdev_pool_put_impl(spool, tgt, spool->xsp_owner);
>> + }
>> +}
>> +
>> +void xrt_subdev_pool_handle_event(struct xrt_subdev_pool *spool, struct xrt_event *evt)
>> +{
>> + struct platform_device *tgt = NULL;
>> + struct xrt_subdev *sdev = NULL;
>> +
>> + while (!xrt_subdev_pool_get_impl(spool, XRT_SUBDEV_MATCH_NEXT,
>> + tgt, spool->xsp_owner, &sdev)) {
>> + tgt = sdev->xs_pdev;
>> + xleaf_ioctl(tgt, XRT_XLEAF_EVENT, evt);
>> + xrt_subdev_pool_put_impl(spool, tgt, spool->xsp_owner);
>> + }
>> +}
>> +
>> +ssize_t xrt_subdev_pool_get_holders(struct xrt_subdev_pool *spool,
>> + struct platform_device *pdev, char *buf, size_t len)
>> +{
>> + const struct list_head *ptr;
>> + struct mutex *lk = &spool->xsp_lock;
>> + struct list_head *dl = &spool->xsp_dev_list;
>> + struct xrt_subdev *sdev;
>> + ssize_t ret = 0;
>> +
>> + mutex_lock(lk);
>> + list_for_each(ptr, dl) {
>> + sdev = list_entry(ptr, struct xrt_subdev, xs_dev_list);
>> + if (sdev->xs_pdev != pdev)
>> + continue;
>> + ret = xrt_subdev_get_holders(sdev, buf, len);
>> + break;
>> + }
>> + mutex_unlock(lk);
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(xrt_subdev_pool_get_holders);
>> +
>> +int xleaf_broadcast_event(struct platform_device *pdev, enum xrt_events evt, bool async)
>> +{
>> + struct xrt_event e = { evt, };
>> + u32 cmd = async ? XRT_ROOT_EVENT_ASYNC : XRT_ROOT_EVENT;
>> +
>> + WARN_ON(evt == XRT_EVENT_POST_CREATION || evt == XRT_EVENT_PRE_REMOVAL);
>> + return xrt_subdev_root_request(pdev, cmd, &e);
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_broadcast_event);
>> +
>> +void xleaf_hot_reset(struct platform_device *pdev)
>> +{
>> + xrt_subdev_root_request(pdev, XRT_ROOT_HOT_RESET, NULL);
>> +}
>> +EXPORT_SYMBOL_GPL(xleaf_hot_reset);
>> +
>> +void xleaf_get_barres(struct platform_device *pdev, struct resource **res, uint bar_idx)
>> +{
>> + struct xrt_root_ioctl_get_res arg = { 0 };
>> +
>> + if (bar_idx > PCI_STD_RESOURCE_END) {
>> + xrt_err(pdev, "Invalid bar idx %d", bar_idx);
>> + *res = NULL;
>> + return;
>> + }
>> +
>> + xrt_subdev_root_request(pdev, XRT_ROOT_GET_RESOURCE, &arg);
>> +
>> + *res = &arg.xpigr_res[bar_idx];
> is this correct ?
>
> do all res need to be found to return a single one ?

It does not seem to hurt to do so, if the code is simpler. Do you see a
bug here?

>> +}
>> +
>> +void xleaf_get_root_id(struct platform_device *pdev, unsigned short *vendor, unsigned short *device,
>> + unsigned short *subvendor, unsigned short *subdevice)
>> +{
>> + struct xrt_root_ioctl_get_id id = { 0 };
>> +
>> + xrt_subdev_root_request(pdev, XRT_ROOT_GET_ID, (void *)&id);
>> + if (vendor)
>> + *vendor = id.xpigi_vendor_id;
>> + if (device)
>> + *device = id.xpigi_device_id;
>> + if (subvendor)
>> + *subvendor = id.xpigi_sub_vendor_id;
>> + if (subdevice)
>> + *subdevice = id.xpigi_sub_device_id;
> not setting anything because user passed in all nulls would make this function a noop.

Will add a warning, if all pointers passed in are NULL.

>> +}
>> +
>> +struct device *xleaf_register_hwmon(struct platform_device *pdev, const char *name, void *drvdata,
>> + const struct attribute_group **grps)
>> +{
>> + struct xrt_root_ioctl_hwmon hm = { true, name, drvdata, grps, };
>> +
>> + xrt_subdev_root_request(pdev, XRT_ROOT_HWMON, (void *)&hm);
>> + return hm.xpih_hwmon_dev;
>> +}
>> +
>> +void xleaf_unregister_hwmon(struct platform_device *pdev, struct device *hwmon)
>> +{
>> + struct xrt_root_ioctl_hwmon hm = { false, };
>> +
>> + hm.xpih_hwmon_dev = hwmon;
>> + xrt_subdev_root_request(pdev, XRT_ROOT_HWMON, (void *)&hm);
>> +}
>> diff --git a/drivers/fpga/xrt/lib/subdev_pool.h b/drivers/fpga/xrt/lib/subdev_pool.h
>> new file mode 100644
>> index 000000000000..50a8490e0e41
> apologies for delay, was busy.
>
> If it seems like i forgot a train of thought, i did.
>
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/lib/subdev_pool.h
>> @@ -0,0 +1,53 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Header file for Xilinx Runtime (XRT) driver
>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + * Cheng Zhen<maxz@xilinx.com>
>> + */
>> +
>> +#ifndef _XRT_SUBDEV_POOL_H_
>> +#define _XRT_SUBDEV_POOL_H_
>> +
>> +#include "xroot.h"
>> +
>> +/*
>> + * It manages a list of xrt_subdevs for root and group drivers.
> 'It' does not have a lot of context, better would be
>
> The xrt_subdev_pool struct ..

Sure.

>> + */
>> +struct xrt_subdev_pool {
>> + struct list_head xsp_dev_list;
>> + struct device *xsp_owner;
>> + struct mutex xsp_lock; /* pool lock */
> Header files should be self contained, a quick look at xroot.h makes me suspicious that device and mutex decls assume the includer has added their headers before this one

Will add these two headers here.

>> + bool xsp_closing;
> If you thing additional state will be needed, you could change this to a bitfield. sizewise with compiler padding i don't think the size would change.

Will consider using a bit flag in the future when more state is needed.

>> +};
>> +
>> +/*
>> + * Subdev pool API for root and group drivers only.
> 'API' makes me think these should go in include/linux/fpga
>
> Do/will these functions get called outside of the drivers/fpga ?

No, these are internal functions. Will change "API" to "helper functions".

>> + */
>> +void xrt_subdev_pool_init(struct device *dev,
>> + struct xrt_subdev_pool *spool);
>> +void xrt_subdev_pool_fini(struct xrt_subdev_pool *spool);
>> +int xrt_subdev_pool_get(struct xrt_subdev_pool *spool,
>> + xrt_subdev_match_t match,
>> + void *arg, struct device *holder_dev,
>> + struct platform_device **pdevp);
>> +int xrt_subdev_pool_put(struct xrt_subdev_pool *spool,
>> + struct platform_device *pdev,
>> + struct device *holder_dev);
>> +int xrt_subdev_pool_add(struct xrt_subdev_pool *spool,
>> + enum xrt_subdev_id id, xrt_subdev_root_cb_t pcb,
>> + void *pcb_arg, char *dtb);
>> +int xrt_subdev_pool_del(struct xrt_subdev_pool *spool,
>> + enum xrt_subdev_id id, int instance);
>> +ssize_t xrt_subdev_pool_get_holders(struct xrt_subdev_pool *spool,
>> + struct platform_device *pdev,
>> + char *buf, size_t len);
>> +
>> +void xrt_subdev_pool_trigger_event(struct xrt_subdev_pool *spool,
>> + enum xrt_events evt);
>> +void xrt_subdev_pool_handle_event(struct xrt_subdev_pool *spool,
>> + struct xrt_event *evt);
>> +
>> +#endif /* _XRT_SUBDEV_POOL_H_ */
>> diff --git a/drivers/fpga/xrt/lib/xroot.c b/drivers/fpga/xrt/lib/xroot.c
>> new file mode 100644
>> index 000000000000..3dc7b0243277
>> --- /dev/null
>> +++ b/drivers/fpga/xrt/lib/xroot.c
>> @@ -0,0 +1,598 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Xilinx Alveo FPGA Root Functions
>> + *
>> + * Copyright (C) 2020-2021 Xilinx, Inc.
>> + *
>> + * Authors:
>> + * Cheng Zhen<maxz@xilinx.com>
>> + */
>> +
>> +#include <linux/module.h>
>> +#include <linux/pci.h>
>> +#include <linux/hwmon.h>
>> +#include "xroot.h"
>> +#include "subdev_pool.h"
>> +#include "group.h"
>> +#include "metadata.h"
>> +
>> +#define XROOT_PDEV(xr) ((xr)->pdev)
>> +#define XROOT_DEV(xr) (&(XROOT_PDEV(xr)->dev))
>> +#define xroot_err(xr, fmt, args...) \
>> + dev_err(XROOT_DEV(xr), "%s: " fmt, __func__, ##args)
>> +#define xroot_warn(xr, fmt, args...) \
>> + dev_warn(XROOT_DEV(xr), "%s: " fmt, __func__, ##args)
>> +#define xroot_info(xr, fmt, args...) \
>> + dev_info(XROOT_DEV(xr), "%s: " fmt, __func__, ##args)
>> +#define xroot_dbg(xr, fmt, args...) \
>> + dev_dbg(XROOT_DEV(xr), "%s: " fmt, __func__, ##args)
>> +
>> +#define XRT_VSEC_ID 0x20
> Is this the best place to define some pci magic ?
>
> It looks like the xroot is combination of the root of the device tree and the pci setup for the board.
>
> Can the pci-ness be split and the root mostly handling how the subtrees are organized ?

Root driver is a PCIE device driver by design, so it makes sense to
define pci specific stuff here. It manages the set of group drivers by
calling into above pool API. So, the code has already been split.

>> +
>> +#define XROOT_GRP_FIRST (-1)
>> +#define XROOT_GRP_LAST (-2)
>> +
>> +static int xroot_root_cb(struct device *, void *, u32, void *);
>> +
>> +struct xroot_evt {
>> + struct list_head list;
>> + struct xrt_event evt;
>> + struct completion comp;
>> + bool async;
>> +};
>> +
>> +struct xroot_events {
>> + struct mutex evt_lock; /* event lock */
>> + struct list_head evt_list;
>> + struct work_struct evt_work;
>> +};
>> +
>> +struct xroot_grps {
>> + struct xrt_subdev_pool pool;
>> + struct work_struct bringup_work;
>> + atomic_t bringup_pending;
>> + atomic_t bringup_failed;
> combine with bitfield

These two are counters, not bit flags.

>> + struct completion bringup_comp;
>> +};
>> +
>> +struct xroot {
>> + struct pci_dev *pdev;
>> + struct xroot_events events;
>> + struct xroot_grps grps;
>> + struct xroot_pf_cb pf_cb;
> expand pf_cb, maybe 'physical_function_callback' ?

Sure.

>> +};
>> +
>> +struct xroot_grp_match_arg {
>> + enum xrt_subdev_id id;
>> + int instance;
>> +};
>> +
>> +static bool xroot_grp_match(enum xrt_subdev_id id,
>> + struct platform_device *pdev, void *arg)
>> +{
>> + struct xroot_grp_match_arg *a = (struct xroot_grp_match_arg *)arg;
>> + return id == a->id && pdev->id == a->instance;
> scanning the code i expected to see ... && pdev->instance == a->instance
>
> pdev->id == a->instance looks like a bug, a change to pdev->id element name to pdev->instance or in needed of a comment.

pdev is of struct platform_device type, so we can't change. I will add a
comment.

>> +}
>> +
>> +static int xroot_get_group(struct xroot *xr, int instance,
>> + struct platform_device **grpp)
>> +{
>> + int rc = 0;
>> + struct xrt_subdev_pool *grps = &xr->grps.pool;
>> + struct device *dev = DEV(xr->pdev);
>> + struct xroot_grp_match_arg arg = { XRT_SUBDEV_GRP, instance };
>> +
>> + if (instance == XROOT_GRP_LAST) {
>> + rc = xrt_subdev_pool_get(grps, XRT_SUBDEV_MATCH_NEXT,
>> + *grpp, dev, grpp);
>> + } else if (instance == XROOT_GRP_FIRST) {
>> + rc = xrt_subdev_pool_get(grps, XRT_SUBDEV_MATCH_PREV,
>> + *grpp, dev, grpp);
> For consistency, maybe the suffix of ...MATCH_NEXT/PREV should be changed to LAST/FIRST

It is only for finding last and first when the referring device passed
in is NULL. Otherwise, it is next and prev. So, can't really change here.

>> + } else {
>> + rc = xrt_subdev_pool_get(grps, xroot_grp_match,
>> + &arg, dev, grpp);
>> + }
>> +
>> + if (rc && rc != -ENOENT)
>> + xroot_err(xr, "failed to hold group %d: %d", instance, rc);
>> + return rc;
>> +}
>> +
>> +static void xroot_put_group(struct xroot *xr, struct platform_device *grp)
>> +{
>> + int inst = grp->id;
>> + int rc = xrt_subdev_pool_put(&xr->grps.pool, grp, DEV(xr->pdev));
>> +
>> + if (rc)
>> + xroot_err(xr, "failed to release group %d: %d", inst, rc);
>> +}
>> +
>> +static int xroot_trigger_event(struct xroot *xr,
>> + struct xrt_event *e, bool async)
>> +{
>> + struct xroot_evt *enew = vzalloc(sizeof(*enew));
>> +
>> + if (!enew)
>> + return -ENOMEM;
>> +
>> + enew->evt = *e;
>> + enew->async = async;
>> + init_completion(&enew->comp);
>> +
>> + mutex_lock(&xr->events.evt_lock);
>> + list_add(&enew->list, &xr->events.evt_list);
>> + mutex_unlock(&xr->events.evt_lock);
>> +
>> + schedule_work(&xr->events.evt_work);
>> +
>> + if (async)
>> + return 0;
>> +
>> + wait_for_completion(&enew->comp);
>> + vfree(enew);
>> + return 0;
>> +}
>> +
>> +static void
>> +xroot_group_trigger_event(struct xroot *xr, int inst, enum xrt_events e)
>> +{
>> + int ret;
>> + struct platform_device *pdev = NULL;
>> + struct xrt_event evt = { 0 };
>> +
>> + WARN_ON(inst < 0);
>> + /* Only triggers subdev specific events. */
>> + if (e != XRT_EVENT_POST_CREATION && e != XRT_EVENT_PRE_REMOVAL) {
>> + xroot_err(xr, "invalid event %d", e);
>> + return;
>> + }
>> +
>> + ret = xroot_get_group(xr, inst, &pdev);
>> + if (ret)
>> + return;
>> +
>> + /* Triggers event for children, first. */
>> + (void)xleaf_ioctl(pdev, XRT_GROUP_TRIGGER_EVENT, (void *)(uintptr_t)e);
> These voids are not needed, but maybe error checking is.

It is OK for this to fail. The driver handler will issue error or
warning message. I'll remove the voids.

>> +
>> + /* Triggers event for itself. */
>> + evt.xe_evt = e;
>> + evt.xe_subdev.xevt_subdev_id = XRT_SUBDEV_GRP;
>> + evt.xe_subdev.xevt_subdev_instance = inst;
>> + (void)xroot_trigger_event(xr, &evt, false);
>> +
>> + (void)xroot_put_group(xr, pdev);
>> +}
>> +
>> +int xroot_create_group(void *root, char *dtb)
>> +{
>> + struct xroot *xr = (struct xroot *)root;
>> + int ret;
>> +
>> + atomic_inc(&xr->grps.bringup_pending);
> could this state and the error be moved to xrt_sbudev_pool_add where locking happens so atomics are not needed ?

This is marked so that xrt_subdev_pool_add can be called later on it.
So, can't be moved.

>> + ret = xrt_subdev_pool_add(&xr->grps.pool, XRT_SUBDEV_GRP,
>> + xroot_root_cb, xr, dtb);
>> + if (ret >= 0) {
>> + schedule_work(&xr->grps.bringup_work);
>> + } else {
>> + atomic_dec(&xr->grps.bringup_pending);
>> + atomic_inc(&xr->grps.bringup_failed);
>> + xroot_err(xr, "failed to create group: %d", ret);
>> + }
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(xroot_create_group);
>> +
>> +static int xroot_destroy_single_group(struct xroot *xr, int instance)
>> +{
> A better name would be 'xroot_destroy_group'

"group" and "groups" look too close. I'd like to have a 'single' here to
make the code less confusing.

>> + struct platform_device *pdev = NULL;
>> + int ret;
>> +
>> + WARN_ON(instance < 0);
>> + ret = xroot_get_group(xr, instance, &pdev);
>> + if (ret)
>> + return ret;
>> +
>> + xroot_group_trigger_event(xr, instance, XRT_EVENT_PRE_REMOVAL);
>> +
>> + /* Now tear down all children in this group. */
>> + ret = xleaf_ioctl(pdev, XRT_GROUP_FINI_CHILDREN, NULL);
>> + (void)xroot_put_group(xr, pdev);
>> + if (!ret) {
>> + ret = xrt_subdev_pool_del(&xr->grps.pool, XRT_SUBDEV_GRP,
>> + instance);
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static int xroot_destroy_group(struct xroot *xr, int instance)
> A better name would be 'xroot_destroy_groups'

Please see my above comment.

>> +{
>> + struct platform_device *target = NULL;
>> + struct platform_device *deps = NULL;
>> + int ret;
>> +
>> + WARN_ON(instance < 0);
>> + /*
>> + * Make sure target group exists and can't go away before
>> + * we remove it's dependents
>> + */
>> + ret = xroot_get_group(xr, instance, &target);
>> + if (ret)
>> + return ret;
>> +
>> + /*
>> + * Remove all groups depend on target one.
>> + * Assuming subdevs in higher group ID can depend on ones in
>> + * lower ID groups, we remove them in the reservse order.
>> + */
>> + while (xroot_get_group(xr, XROOT_GRP_LAST, &deps) != -ENOENT) {
>> + int inst = deps->id;
>> +
>> + xroot_put_group(xr, deps);
>> + if (instance == inst)
>> + break;
> breaking in the middle does not seem correct.
>
> please add a comment

Will add a comment.

>> + (void)xroot_destroy_single_group(xr, inst);
>> + deps = NULL;
>> + }
>> +
>> + /* Now we can remove the target group. */
>> + xroot_put_group(xr, target);
>> + return xroot_destroy_single_group(xr, instance);
>> +}
>> +
>> +static int xroot_lookup_group(struct xroot *xr,
>> + struct xrt_root_ioctl_lookup_group *arg)
>> +{
>> + int rc = -ENOENT;
>> + struct platform_device *grp = NULL;
>> +
>> + while (rc < 0 && xroot_get_group(xr, XROOT_GRP_LAST, &grp) != -ENOENT) {
>> + if (arg->xpilp_match_cb(XRT_SUBDEV_GRP, grp,
>> + arg->xpilp_match_arg)) {
>> + rc = grp->id;
>> + }
>> + xroot_put_group(xr, grp);
>> + }
>> + return rc;
>> +}
>> +
>> +static void xroot_event_work(struct work_struct *work)
>> +{
>> + struct xroot_evt *tmp;
>> + struct xroot *xr = container_of(work, struct xroot, events.evt_work);
>> +
>> + mutex_lock(&xr->events.evt_lock);
>> + while (!list_empty(&xr->events.evt_list)) {
>> + tmp = list_first_entry(&xr->events.evt_list,
>> + struct xroot_evt, list);
>> + list_del(&tmp->list);
>> + mutex_unlock(&xr->events.evt_lock);
> why is unlocking necessary ?

It'd be better to release the lock when you call into other code module
to avoid any potential deadlock.

>> +
>> + (void)xrt_subdev_pool_handle_event(&xr->grps.pool, &tmp->evt);
>> +
>> + if (tmp->async)
>> + vfree(tmp);
>> + else
>> + complete(&tmp->comp);
>> +
>> + mutex_lock(&xr->events.evt_lock);
>> + }
>> + mutex_unlock(&xr->events.evt_lock);
>> +}
>> +
>> +static void xroot_event_init(struct xroot *xr)
>> +{
>> + INIT_LIST_HEAD(&xr->events.evt_list);
>> + mutex_init(&xr->events.evt_lock);
>> + INIT_WORK(&xr->events.evt_work, xroot_event_work);
>> +}
>> +
>> +static void xroot_event_fini(struct xroot *xr)
>> +{
>> + flush_scheduled_work();
>> + WARN_ON(!list_empty(&xr->events.evt_list));
>> +}
>> +
>> +static int xroot_get_leaf(struct xroot *xr, struct xrt_root_ioctl_get_leaf *arg)
>> +{
>> + int rc = -ENOENT;
>> + struct platform_device *grp = NULL;
>> +
>> + while (rc && xroot_get_group(xr, XROOT_GRP_LAST, &grp) != -ENOENT) {
> while (rc) ?
>
> while we see an error on xleaf_ioctl, keep going ?
>
> Seems like would rather have !rc

The root is trying to call into each group to find a leaf instance. If
xleaf_call returns error, it means that it can't find it. So, we
continue with next group.

> similar below in put_leaf

See my comment above.

>> + rc = xleaf_ioctl(grp, XRT_GROUP_GET_LEAF, arg);
>> + xroot_put_group(xr, grp);
>> + }
>> + return rc;
>> +}
>> +
>> +static int xroot_put_leaf(struct xroot *xr, struct xrt_root_ioctl_put_leaf *arg)
>> +{
>> + int rc = -ENOENT;
>> + struct platform_device *grp = NULL;
>> +
>> + while (rc && xroot_get_group(xr, XROOT_GRP_LAST, &grp) != -ENOENT) {
>> + rc = xleaf_ioctl(grp, XRT_GROUP_PUT_LEAF, arg);
>> + xroot_put_group(xr, grp);
>> + }
>> + return rc;
>> +}
>> +
>> +static int xroot_root_cb(struct device *dev, void *parg, u32 cmd, void *arg)
>> +{
>> + struct xroot *xr = (struct xroot *)parg;
>> + int rc = 0;
>> +
>> + switch (cmd) {
>> + /* Leaf actions. */
>> + case XRT_ROOT_GET_LEAF: {
>> + struct xrt_root_ioctl_get_leaf *getleaf =
>> + (struct xrt_root_ioctl_get_leaf *)arg;
>> + rc = xroot_get_leaf(xr, getleaf);
>> + break;
>> + }
>> + case XRT_ROOT_PUT_LEAF: {
>> + struct xrt_root_ioctl_put_leaf *putleaf =
>> + (struct xrt_root_ioctl_put_leaf *)arg;
>> + rc = xroot_put_leaf(xr, putleaf);
>> + break;
>> + }
> looking at these two cases without any changes to arg but a cast, i think these and the next pass the void * onto the function and have the function manage the cast.

The functions are not only called inside xroot_root_cb(), so it does not
make sense to force other callers to pass a void *.

>> + case XRT_ROOT_GET_LEAF_HOLDERS: {
>> + struct xrt_root_ioctl_get_holders *holders =
>> + (struct xrt_root_ioctl_get_holders *)arg;
>> + rc = xrt_subdev_pool_get_holders(&xr->grps.pool,
>> + holders->xpigh_pdev,
>> + holders->xpigh_holder_buf,
>> + holders->xpigh_holder_buf_len);
>> + break;
>> + }
>> +
>> + /* Group actions. */
>> + case XRT_ROOT_CREATE_GROUP:
>> + rc = xroot_create_group(xr, (char *)arg);
>> + break;
>> + case XRT_ROOT_REMOVE_GROUP:
>> + rc = xroot_destroy_group(xr, (int)(uintptr_t)arg);
>> + break;
>> + case XRT_ROOT_LOOKUP_GROUP: {
>> + struct xrt_root_ioctl_lookup_group *getgrp =
>> + (struct xrt_root_ioctl_lookup_group *)arg;
>> + rc = xroot_lookup_group(xr, getgrp);
>> + break;
>> + }
>> + case XRT_ROOT_WAIT_GROUP_BRINGUP:
>> + rc = xroot_wait_for_bringup(xr) ? 0 : -EINVAL;
>> + break;
>> +
>> + /* Event actions. */
>> + case XRT_ROOT_EVENT:
>> + case XRT_ROOT_EVENT_ASYNC: {
>> + bool async = (cmd == XRT_ROOT_EVENT_ASYNC);
>> + struct xrt_event *evt = (struct xrt_event *)arg;
>> +
>> + rc = xroot_trigger_event(xr, evt, async);
>> + break;
>> + }
>> +
>> + /* Device info. */
>> + case XRT_ROOT_GET_RESOURCE: {
>> + struct xrt_root_ioctl_get_res *res =
>> + (struct xrt_root_ioctl_get_res *)arg;
>> + res->xpigr_res = xr->pdev->resource;
>> + break;
>> + }
>> + case XRT_ROOT_GET_ID: {
>> + struct xrt_root_ioctl_get_id *id =
>> + (struct xrt_root_ioctl_get_id *)arg;
>> +
>> + id->xpigi_vendor_id = xr->pdev->vendor;
>> + id->xpigi_device_id = xr->pdev->device;
>> + id->xpigi_sub_vendor_id = xr->pdev->subsystem_vendor;
>> + id->xpigi_sub_device_id = xr->pdev->subsystem_device;
>> + break;
>> + }
>> +
>> + /* MISC generic PCIE driver functions. */
> misc functions may need a need some place else.
>
> Is there a way to extend the cmd with some additional layer of abstraction ?

Not sure why there is a need to do so? It is misc, but also PCIE related
services. They just can't be grouped with others, but does not really
mean there is need for another layer?

>> + case XRT_ROOT_HOT_RESET: {
>> + xr->pf_cb.xpc_hot_reset(xr->pdev);
>> + break;
>> + }
>> + case XRT_ROOT_HWMON: {
>> + struct xrt_root_ioctl_hwmon *hwmon =
>> + (struct xrt_root_ioctl_hwmon *)arg;
>> +
>> + if (hwmon->xpih_register) {
>> + hwmon->xpih_hwmon_dev =
>> + hwmon_device_register_with_info(DEV(xr->pdev),
>> + hwmon->xpih_name,
>> + hwmon->xpih_drvdata,
>> + NULL,
>> + hwmon->xpih_groups);
>> + } else {
>> + (void)hwmon_device_unregister(hwmon->xpih_hwmon_dev);
>> + }
>> + break;
>> + }
>> +
>> + default:
>> + xroot_err(xr, "unknown IOCTL cmd %d", cmd);
>> + rc = -EINVAL;
>> + break;
>> + }
>> +
>> + return rc;
>> +}
>> +
>> +static void xroot_bringup_group_work(struct work_struct *work)
>> +{
>> + struct platform_device *pdev = NULL;
>> + struct xroot *xr = container_of(work, struct xroot, grps.bringup_work);
>> +
>> + while (xroot_get_group(xr, XROOT_GRP_FIRST, &pdev) != -ENOENT) {
>> + int r, i;
>> +
>> + i = pdev->id;
>> + r = xleaf_ioctl(pdev, XRT_GROUP_INIT_CHILDREN, NULL);
>> + (void)xroot_put_group(xr, pdev);
>> + if (r == -EEXIST)
>> + continue; /* Already brough up, nothing to do. */
>> + if (r)
>> + atomic_inc(&xr->grps.bringup_failed);
>> +
>> + xroot_group_trigger_event(xr, i, XRT_EVENT_POST_CREATION);
>> +
>> + if (atomic_dec_and_test(&xr->grps.bringup_pending))
>> + complete(&xr->grps.bringup_comp);
>> + }
>> +}
>> +
>> +static void xroot_grps_init(struct xroot *xr)
> Consistency in terms is needed. In the last few lines i see
>
> group, grp, grps, my vote is for group(s)

Will use group(s) in struct and function names. Will use grp(s) in
variable names.

>> +{
>> + xrt_subdev_pool_init(DEV(xr->pdev), &xr->grps.pool);
>> + INIT_WORK(&xr->grps.bringup_work, xroot_bringup_group_work);
>> + atomic_set(&xr->grps.bringup_pending, 0);
>> + atomic_set(&xr->grps.bringup_failed, 0);
>> + init_completion(&xr->grps.bringup_comp);
>> +}
>> +
>> +static void xroot_grps_fini(struct xroot *xr)
>> +{
>> + flush_scheduled_work();
>> + xrt_subdev_pool_fini(&xr->grps.pool);
>> +}
>> +
>> +int xroot_add_vsec_node(void *root, char *dtb)
>> +{
> This is the pci part i think needs to move to its own file.

Please see my comment above.

>> + struct xroot *xr = (struct xroot *)root;
>> + struct device *dev = DEV(xr->pdev);
>> + struct xrt_md_endpoint ep = { 0 };
>> + int cap = 0, ret = 0;
>> + u32 off_low, off_high, vsec_bar, header;
>> + u64 vsec_off;
>> +
>> + while ((cap = pci_find_next_ext_capability(xr->pdev, cap,
>> + PCI_EXT_CAP_ID_VNDR))) {
>> + pci_read_config_dword(xr->pdev, cap + PCI_VNDR_HEADER, &header);
>> + if (PCI_VNDR_HEADER_ID(header) == XRT_VSEC_ID)
>> + break;
>> + }
>> + if (!cap) {
>> + xroot_info(xr, "No Vendor Specific Capability.");
>> + return -ENOENT;
>> + }
>> +
>> + if (pci_read_config_dword(xr->pdev, cap + 8, &off_low) ||
>> + pci_read_config_dword(xr->pdev, cap + 12, &off_high)) {
>> + xroot_err(xr, "pci_read vendor specific failed.");
>> + return -EINVAL;
>> + }
>> +
>> + ep.ep_name = XRT_MD_NODE_VSEC;
>> + ret = xrt_md_add_endpoint(dev, dtb, &ep);
>> + if (ret) {
>> + xroot_err(xr, "add vsec metadata failed, ret %d", ret);
>> + goto failed;
>> + }
>> +
>> + vsec_bar = cpu_to_be32(off_low & 0xf);
>> + ret = xrt_md_set_prop(dev, dtb, XRT_MD_NODE_VSEC, NULL,
>> + XRT_MD_PROP_BAR_IDX, &vsec_bar, sizeof(vsec_bar));
>> + if (ret) {
>> + xroot_err(xr, "add vsec bar idx failed, ret %d", ret);
>> + goto failed;
>> + }
>> +
>> + vsec_off = cpu_to_be64(((u64)off_high << 32) | (off_low & ~0xfU));
>> + ret = xrt_md_set_prop(dev, dtb, XRT_MD_NODE_VSEC, NULL,
>> + XRT_MD_PROP_OFFSET, &vsec_off, sizeof(vsec_off));
>> + if (ret) {
>> + xroot_err(xr, "add vsec offset failed, ret %d", ret);
>> + goto failed;
>> + }
>> +
>> +failed:
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(xroot_add_vsec_node);
>> +
>> +int xroot_add_simple_node(void *root, char *dtb, const char *endpoint)
>> +{
>> + struct xroot *xr = (struct xroot *)root;
>> + struct device *dev = DEV(xr->pdev);
>> + struct xrt_md_endpoint ep = { 0 };
>> + int ret = 0;
>> +
>> + ep.ep_name = endpoint;
>> + ret = xrt_md_add_endpoint(dev, dtb, &ep);
>> + if (ret)
>> + xroot_err(xr, "add %s failed, ret %d", endpoint, ret);
>> +
>> + return ret;
>> +}
>> +EXPORT_SYMBOL_GPL(xroot_add_simple_node);
>> +
>> +bool xroot_wait_for_bringup(void *root)
>> +{
>> + struct xroot *xr = (struct xroot *)root;
>> +
>> + wait_for_completion(&xr->grps.bringup_comp);
>> + return atomic_xchg(&xr->grps.bringup_failed, 0) == 0;
> Is there going to a race in intialization ?

There should not be. I'll change it to atomic_read()

>> +}
>> +EXPORT_SYMBOL_GPL(xroot_wait_for_bringup);
>> +
>> +int xroot_probe(struct pci_dev *pdev, struct xroot_pf_cb *cb, void **root)
>> +{
>> + struct device *dev = DEV(pdev);
>> + struct xroot *xr = NULL;
>> +
>> + dev_info(dev, "%s: probing...", __func__);
>> +
>> + xr = devm_kzalloc(dev, sizeof(*xr), GFP_KERNEL);
>> + if (!xr)
>> + return -ENOMEM;
>> +
>> + xr->pdev = pdev;
>> + xr->pf_cb = *cb;
>> + xroot_grps_init(xr);
>> + xroot_event_init(xr);
>> +
>> + *root = xr;
>> + return 0;
>> +}
>> +EXPORT_SYMBOL_GPL(xroot_probe);
>> +
>> +void xroot_remove(void *root)
>> +{
>> + struct xroot *xr = (struct xroot *)root;
>> + struct platform_device *grp = NULL;
>> +
>> + xroot_info(xr, "leaving...");
>> +
>> + if (xroot_get_group(xr, XROOT_GRP_FIRST, &grp) == 0) {
>> + int instance = grp->id;
> another instance = id, the variable and element names should be consistent.
>
> earlier (id, instance) is used to uniquely determine a node. if that is so then using the names should be kept seperate.

grp is also of struct platform_device, so we can't change. But, really
grp->id is the instance.

>> +
>> + xroot_put_group(xr, grp);
>> + (void)xroot_destroy_group(xr, instance);
>> + }
>> +
>> + xroot_event_fini(xr);
>> + xroot_grps_fini(xr);
>> +}
>> +EXPORT_SYMBOL_GPL(xroot_remove);
>> +
>> +void xroot_broadcast(void *root, enum xrt_events evt)
>> +{
>> + struct xroot *xr = (struct xroot *)root;
>> + struct xrt_event e = { 0 };
>> +
>> + /* Root pf driver only broadcasts below two events. */
>> + if (evt != XRT_EVENT_POST_CREATION && evt != XRT_EVENT_PRE_REMOVAL) {
>> + xroot_info(xr, "invalid event %d", evt);
>> + return;
>> + }
>> +
>> + e.xe_evt = evt;
>> + e.xe_subdev.xevt_subdev_id = XRT_ROOT;
>> + e.xe_subdev.xevt_subdev_instance = 0;
> see..
>
> id =
>
> instance =

->id is part of the platform_device framework, we can't change.

Thanks,

Max

> Tom
>
>> + (void)xroot_trigger_event(xr, &e, false);
>> +}
>> +EXPORT_SYMBOL_GPL(xroot_broadcast);