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Date:   Thu, 23 Jun 2022 15:33:25 +0000
From:   "Kubalewski, Arkadiusz" <arkadiusz.kubalewski@...el.com>
To:     Vadim Fedorenko <vfedorenko@...ek.ru>,
        Jakub Kicinski <kuba@...nel.org>
CC:     Vadim Fedorenko <vadfed@...com>, Aya Levin <ayal@...dia.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [RFC PATCH v1 1/3] dpll: Add DPLL framework base functions

Hi Vadim,

Great work!

Although, I've been thinking that you already forget about it, so I have
started development of something similar.


-----Original Message-----
From: Vadim Fedorenko <vfedorenko@...ek.ru> 
Sent: Thursday, June 23, 2022 2:57 AM
> 
> From: Vadim Fedorenko <vadfed@...com>
> 
> DPLL framework is used to represent and configure DPLL devices
> in systems. Each device that has DPLL and can configure sources
> and outputs can use this framework.
> 
> Signed-off-by: Vadim Fedorenko <vadfed@...com>
> ---
>  MAINTAINERS                 |   8 +
>  drivers/Kconfig             |   2 +
>  drivers/Makefile            |   1 +
>  drivers/dpll/Kconfig        |   7 +
>  drivers/dpll/Makefile       |   7 +
>  drivers/dpll/dpll_core.c    | 152 +++++++++++++
>  drivers/dpll/dpll_core.h    |  40 ++++
>  drivers/dpll/dpll_netlink.c | 437 ++++++++++++++++++++++++++++++++++++
>  drivers/dpll/dpll_netlink.h |   7 +
>  include/linux/dpll.h        |  25 +++
>  include/uapi/linux/dpll.h   |  77 +++++++
>  11 files changed, 763 insertions(+)
>  create mode 100644 drivers/dpll/Kconfig
>  create mode 100644 drivers/dpll/Makefile
>  create mode 100644 drivers/dpll/dpll_core.c
>  create mode 100644 drivers/dpll/dpll_core.h
>  create mode 100644 drivers/dpll/dpll_netlink.c
>  create mode 100644 drivers/dpll/dpll_netlink.h
>  create mode 100644 include/linux/dpll.h
>  create mode 100644 include/uapi/linux/dpll.h
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 05fcbea3e432..5532130baf36 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6122,6 +6122,14 @@ F:	Documentation/networking/device_drivers/ethernet/freescale/dpaa2/switch-drive
>  F:	drivers/net/ethernet/freescale/dpaa2/dpaa2-switch*
>  F:	drivers/net/ethernet/freescale/dpaa2/dpsw*
>  
> +DPLL CLOCK SUBSYSTEM
> +M:	Vadim Fedorenko <vadfed@...com>
> +L:	netdev@...r.kernel.org
> +S:	Maintained
> +F:	drivers/dpll/*
> +F:	include/net/dpll.h
> +F:	include/uapi/linux/dpll.h
> +
>  DPT_I2O SCSI RAID DRIVER
>  M:	Adaptec OEM Raid Solutions <aacraid@...rosemi.com>
>  L:	linux-scsi@...r.kernel.org
> diff --git a/drivers/Kconfig b/drivers/Kconfig
> index b6a172d32a7d..dcdc23116eb8 100644
> --- a/drivers/Kconfig
> +++ b/drivers/Kconfig
> @@ -241,4 +241,6 @@ source "drivers/peci/Kconfig"
>  
>  source "drivers/hte/Kconfig"
>  
> +source "drivers/dpll/Kconfig"
> +
>  endmenu
> diff --git a/drivers/Makefile b/drivers/Makefile
> index 9a30842b22c5..acc370a2cda6 100644
> --- a/drivers/Makefile
> +++ b/drivers/Makefile
> @@ -189,3 +189,4 @@ obj-$(CONFIG_COUNTER)		+= counter/
>  obj-$(CONFIG_MOST)		+= most/
>  obj-$(CONFIG_PECI)		+= peci/
>  obj-$(CONFIG_HTE)		+= hte/
> +obj-$(CONFIG_DPLL)		+= dpll/
> diff --git a/drivers/dpll/Kconfig b/drivers/dpll/Kconfig
> new file mode 100644
> index 000000000000..a4cae73f20d3
> --- /dev/null
> +++ b/drivers/dpll/Kconfig
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +#
> +# Generic DPLL drivers configuration
> +#
> +
> +config DPLL
> +  bool

for RFC help and default were ommited?

> diff --git a/drivers/dpll/Makefile b/drivers/dpll/Makefile
> new file mode 100644
> index 000000000000..0748c80097e4
> --- /dev/null
> +++ b/drivers/dpll/Makefile
> @@ -0,0 +1,7 @@
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Makefile for DPLL drivers.
> +#
> +
> +obj-$(CONFIG_DPLL)          += dpll_sys.o
> +dpll_sys-y                  += dpll_core.o dpll_netlink.o
> diff --git a/drivers/dpll/dpll_core.c b/drivers/dpll/dpll_core.c
> new file mode 100644
> index 000000000000..e34767e723cf
> --- /dev/null
> +++ b/drivers/dpll/dpll_core.c
> @@ -0,0 +1,152 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + *  dpll_core.c - Generic DPLL Management class support.
> + *
> + *  Copyright (c) 2021 Meta Platforms, Inc. and affiliates
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +
> +#include "dpll_core.h"
> +
> +static DEFINE_MUTEX(dpll_device_xa_lock);
> +static DEFINE_XARRAY_FLAGS(dpll_device_xa, XA_FLAGS_ALLOC);
> +#define DPLL_REGISTERED XA_MARK_1
> +
> +#define ASSERT_DPLL_REGISTERED(d)                                           \
> +	WARN_ON_ONCE(!xa_get_mark(&dpll_device_xa, (d)->id, DPLL_REGISTERED))
> +#define ASSERT_DPLL_NOT_REGISTERED(d)                                      \
> +	WARN_ON_ONCE(xa_get_mark(&dpll_device_xa, (d)->id, DPLL_REGISTERED))
> +
> +
> +int for_each_dpll_device(int id, int (*cb)(struct dpll_device *, void *), void *data)
> +{
> +	struct dpll_device *dpll;
> +	unsigned long index;
> +	int ret = 0;
> +
> +	mutex_lock(&dpll_device_xa_lock);
> +	xa_for_each_start(&dpll_device_xa, index, dpll, id) {
> +		if (!xa_get_mark(&dpll_device_xa, index, DPLL_REGISTERED))
> +			continue;
> +		ret = cb(dpll, data);
> +		if (ret)
> +			break;
> +	}
> +	mutex_unlock(&dpll_device_xa_lock);
> +
> +	return ret;
> +}
> +
> +struct dpll_device *dpll_device_get_by_id(int id)
> +{
> +	struct dpll_device *dpll = NULL;
> +
> +	if (xa_get_mark(&dpll_device_xa, id, DPLL_REGISTERED))
> +		dpll = xa_load(&dpll_device_xa, id);
> +	return dpll;
> +}
> +
> +void *dpll_priv(struct dpll_device *dpll)
> +{
> +	return dpll->priv;
> +}
> +EXPORT_SYMBOL_GPL(dpll_priv);
> +
> +static void dpll_device_release(struct device *dev)
> +{
> +	struct dpll_device *dpll;
> +
> +	dpll = to_dpll_device(dev);
> +
> +	dpll_device_unregister(dpll);
> +
> +	mutex_destroy(&dpll->lock);
> +	kfree(dpll);
> +}
> +
> +static struct class dpll_class = {
> +	.name = "dpll",
> +	.dev_release = dpll_device_release,
> +};
> +
> +struct dpll_device *dpll_device_alloc(struct dpll_device_ops *ops, int sources_count,
> +					 int outputs_count, void *priv)
> +{
> +	struct dpll_device *dpll;
> +	int ret;
> +
> +	dpll = kzalloc(sizeof(*dpll), GFP_KERNEL);
> +	if (!dpll)
> +		return ERR_PTR(-ENOMEM);
> +
> +	mutex_init(&dpll->lock);
> +	dpll->ops = ops;
> +	dpll->dev.class = &dpll_class;
> +	dpll->sources_count = sources_count;
> +	dpll->outputs_count = outputs_count;
> +
> +	mutex_lock(&dpll_device_xa_lock);
> +	ret = xa_alloc(&dpll_device_xa, &dpll->id, dpll, xa_limit_16b, GFP_KERNEL);
> +	if (ret)
> +		goto error;
> +	dev_set_name(&dpll->dev, "dpll%d", dpll->id);
> +	mutex_unlock(&dpll_device_xa_lock);
> +	dpll->priv = priv;
> +
> +	return dpll;
> +
> +error:
> +	mutex_unlock(&dpll_device_xa_lock);
> +	kfree(dpll);
> +	return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(dpll_device_alloc);
> +
> +void dpll_device_register(struct dpll_device *dpll)
> +{
> +	ASSERT_DPLL_NOT_REGISTERED(dpll);
> +
> +	mutex_lock(&dpll_device_xa_lock);
> +	xa_set_mark(&dpll_device_xa, dpll->id, DPLL_REGISTERED);
> +	dpll_notify_device_create(dpll->id, dev_name(&dpll->dev));
> +	mutex_unlock(&dpll_device_xa_lock);
> +}
> +EXPORT_SYMBOL_GPL(dpll_device_register);
> +
> +void dpll_device_unregister(struct dpll_device *dpll)
> +{
> +	ASSERT_DPLL_REGISTERED(dpll);
> +
> +	mutex_lock(&dpll_device_xa_lock);
> +	xa_erase(&dpll_device_xa, dpll->id);
> +	mutex_unlock(&dpll_device_xa_lock);
> +}
> +EXPORT_SYMBOL_GPL(dpll_device_unregister);
> +
> +static int __init dpll_init(void)
> +{
> +	int ret;
> +
> +	ret = dpll_netlink_init();
> +	if (ret)
> +		goto error;
> +
> +	ret = class_register(&dpll_class);
> +	if (ret)
> +		goto unregister_netlink;
> +
> +	return 0;
> +
> +unregister_netlink:
> +	dpll_netlink_finish();
> +error:
> +	mutex_destroy(&dpll_device_xa_lock);
> +	return ret;
> +}
> +subsys_initcall(dpll_init);
> diff --git a/drivers/dpll/dpll_core.h b/drivers/dpll/dpll_core.h
> new file mode 100644
> index 000000000000..5ad3224d5caf
> --- /dev/null
> +++ b/drivers/dpll/dpll_core.h
> @@ -0,0 +1,40 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + *  Copyright (c) 2021 Meta Platforms, Inc. and affiliates
> + */
> +
> +#ifndef __DPLL_CORE_H__
> +#define __DPLL_CORE_H__
> +
> +#include <linux/dpll.h>
> +
> +#include "dpll_netlink.h"
> +
> +/**
> + * struct dpll_device - structure for a DPLL device
> + * @id:		unique id number for each edvice
> + * @dev:	&struct device for this dpll device
> + * @sources_count:	amount of input sources this dpll_device supports
> + * @outputs_count:	amount of outputs this dpll_device supports
> + * @ops:	operations this &dpll_device supports
> + * @lock:	mutex to serialize operations
> + * @priv:	pointer to private information of owner
> + */
> +struct dpll_device {
> +	int id;
> +	struct device dev;
> +	int sources_count;
> +	int outputs_count;
> +	struct dpll_device_ops *ops;
> +	struct mutex lock;
> +	void *priv;
> +};
> +
> +#define to_dpll_device(_dev) \
> +	container_of(_dev, struct dpll_device, dev)
> +
> +int for_each_dpll_device(int id, int (*cb)(struct dpll_device *, void *),
> +			  void *data);
> +struct dpll_device *dpll_device_get_by_id(int id);
> +void dpll_device_unregister(struct dpll_device *dpll);
> +#endif
> diff --git a/drivers/dpll/dpll_netlink.c b/drivers/dpll/dpll_netlink.c
> new file mode 100644
> index 000000000000..0bbdaa6dde8e
> --- /dev/null
> +++ b/drivers/dpll/dpll_netlink.c
> @@ -0,0 +1,437 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Generic netlink for DPLL management framework
> + *
> + * Copyright (c) 2021 Meta Platforms, Inc. and affiliates
> + *
> + */
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <net/genetlink.h>
> +#include "dpll_core.h"
> +
> +#include <uapi/linux/dpll.h>
> +
> +static const struct genl_multicast_group dpll_genl_mcgrps[] = {
> +	{ .name = DPLL_CONFIG_DEVICE_GROUP_NAME, },
> +	{ .name = DPLL_CONFIG_SOURCE_GROUP_NAME, },
> +	{ .name = DPLL_CONFIG_OUTPUT_GROUP_NAME, },
> +	{ .name = DPLL_MONITOR_GROUP_NAME,  },
> +};
> +
> +static const struct nla_policy dpll_genl_get_policy[] = {
> +	[DPLLA_DEVICE_ID]	= { .type = NLA_U32 },
> +	[DPLLA_DEVICE_NAME]	= { .type = NLA_STRING,
> +				    .len = DPLL_NAME_LENGTH },
> +	[DPLLA_FLAGS]		= { .type = NLA_U32 },
> +};
> +
> +static const struct nla_policy dpll_genl_set_source_policy[] = {
> +	[DPLLA_DEVICE_ID]	= { .type = NLA_U32 },
> +	[DPLLA_SOURCE_ID]	= { .type = NLA_U32 },
> +	[DPLLA_SOURCE_TYPE]	= { .type = NLA_U32 },
> +};
> +
> +static const struct nla_policy dpll_genl_set_output_policy[] = {
> +	[DPLLA_DEVICE_ID]	= { .type = NLA_U32 },
> +	[DPLLA_OUTPUT_ID]	= { .type = NLA_U32 },
> +	[DPLLA_OUTPUT_TYPE]	= { .type = NLA_U32 },
> +};
> +
> +struct param {
> +	struct netlink_callback *cb;
> +	struct dpll_device *dpll;
> +	struct nlattr **attrs;
> +	struct sk_buff *msg;
> +	int dpll_id;
> +	int dpll_source_id;
> +	int dpll_source_type;
> +	int dpll_output_id;
> +	int dpll_output_type;
> +};
> +
> +struct dpll_dump_ctx {
> +	struct dpll_device *dev;
> +	int flags;
> +	int pos_idx;
> +	int pos_src_idx;
> +	int pos_out_idx;
> +};
> +
> +typedef int (*cb_t)(struct param *);
> +
> +static struct genl_family dpll_gnl_family;
> +
> +static struct dpll_dump_ctx *dpll_dump_context(struct netlink_callback *cb)
> +{
> +	return (struct dpll_dump_ctx *)cb->ctx;
> +}
> +
> +static int __dpll_cmd_device_dump_one(struct dpll_device *dpll,
> +					   struct sk_buff *msg)
> +{
> +	if (nla_put_u32(msg, DPLLA_DEVICE_ID, dpll->id))
> +		return -EMSGSIZE;
> +
> +	if (nla_put_string(msg, DPLLA_DEVICE_NAME, dev_name(&dpll->dev)))
> +		return -EMSGSIZE;
> +
> +	return 0;
> +}
> +
> +static int __dpll_cmd_dump_sources(struct dpll_device *dpll,
> +					   struct sk_buff *msg)
> +{
> +	struct nlattr *src_attr;
> +	int i, ret = 0, type;
> +
> +	for (i = 0; i < dpll->sources_count; i++) {
> +		src_attr = nla_nest_start(msg, DPLLA_SOURCE);
> +		if (!src_attr) {
> +			ret = -EMSGSIZE;
> +			break;
> +		}
> +		type = dpll->ops->get_source_type(dpll, i);
> +		if (nla_put_u32(msg, DPLLA_SOURCE_ID, i) ||
> +		    nla_put_u32(msg, DPLLA_SOURCE_TYPE, type)) {
> +			nla_nest_cancel(msg, src_attr);
> +			ret = -EMSGSIZE;
> +			break;
> +		}
> +		nla_nest_end(msg, src_attr);
> +	}
> +
> +	return ret;
> +}
> +
> +static int __dpll_cmd_dump_outputs(struct dpll_device *dpll,
> +					   struct sk_buff *msg)
> +{
> +	struct nlattr *out_attr;
> +	int i, ret = 0, type;
> +
> +	for (i = 0; i < dpll->outputs_count; i++) {
> +		out_attr = nla_nest_start(msg, DPLLA_OUTPUT);
> +		if (!out_attr) {
> +			ret = -EMSGSIZE;
> +			break;
> +		}
> +		type = dpll->ops->get_source_type(dpll, i);
> +		if (nla_put_u32(msg, DPLLA_OUTPUT_ID, i) ||
> +		    nla_put_u32(msg, DPLLA_OUTPUT_TYPE, type)) {
> +			nla_nest_cancel(msg, out_attr);
> +			ret = -EMSGSIZE;
> +			break;
> +		}
> +		nla_nest_end(msg, out_attr);
> +	}
> +
> +	return ret;
> +}
> +
> +static int __dpll_cmd_dump_status(struct dpll_device *dpll,
> +					   struct sk_buff *msg)
> +{
> +	int ret;
> +
> +	if (!dpll->ops->get_status && !dpll->ops->get_temp && !dpll->ops->get_lock_status)
> +		return 0;

what if dpll doesn't support one of those commands?

> +
> +	if (dpll->ops->get_status) {
> +		ret = dpll->ops->get_status(dpll);
> +		if (nla_put_u32(msg, DPLLA_STATUS, ret))
> +			return -EMSGSIZE;
> +	}
> +
> +	if (dpll->ops->get_temp) {
> +		ret = dpll->ops->get_status(dpll);
> +		if (nla_put_u32(msg, DPLLA_TEMP, ret))
> +			return -EMSGSIZE;
> +	}

shouldn't be get_temp(dpll)?

> +
> +	if (dpll->ops->get_lock_status) {
> +		ret = dpll->ops->get_lock_status(dpll);
> +		if (nla_put_u32(msg, DPLLA_LOCK_STATUS, ret))
> +			return -EMSGSIZE;
> +	}
> +
> +	return 0;
> +}
> +
> +static int dpll_device_dump_one(struct dpll_device *dev, struct sk_buff *msg, int flags)
> +{
> +	struct nlattr *hdr;
> +	int ret;
> +
> +	hdr = nla_nest_start(msg, DPLLA_DEVICE);
> +	if (!hdr)
> +		return -EMSGSIZE;
> +
> +	mutex_lock(&dev->lock);
> +	ret = __dpll_cmd_device_dump_one(dev, msg);
> +	if (ret)
> +		goto out_cancel_nest;
> +
> +	if (flags & DPLL_FLAG_SOURCES && dev->ops->get_source_type) {
> +		ret = __dpll_cmd_dump_sources(dev, msg);
> +		if (ret)
> +			goto out_cancel_nest;
> +	}
> +
> +	if (flags & DPLL_FLAG_OUTPUTS && dev->ops->get_output_type) {
> +		ret = __dpll_cmd_dump_outputs(dev, msg);
> +		if (ret)
> +			goto out_cancel_nest;
> +	}
> +
> +	if (flags & DPLL_FLAG_STATUS) {
> +		ret = __dpll_cmd_dump_status(dev, msg);
> +		if (ret)
> +			goto out_cancel_nest;
> +	}
> +
> +	mutex_unlock(&dev->lock);
> +	nla_nest_end(msg, hdr);
> +
> +	return 0;
> +
> +out_cancel_nest:
> +	mutex_unlock(&dev->lock);
> +	nla_nest_cancel(msg, hdr);
> +
> +	return ret;
> +}
> +
> +static int dpll_genl_cmd_set_source(struct param *p)
> +{
> +	const struct genl_dumpit_info *info = genl_dumpit_info(p->cb);
> +	struct dpll_device *dpll = p->dpll;
> +	int ret = 0, src_id, type;
> +
> +	if (!info->attrs[DPLLA_SOURCE_ID] ||
> +	    !info->attrs[DPLLA_SOURCE_TYPE])
> +		return -EINVAL;
> +
> +	if (!dpll->ops->set_source_type)
> +		return -EOPNOTSUPP;
> +
> +	src_id = nla_get_u32(info->attrs[DPLLA_SOURCE_ID]);
> +	type = nla_get_u32(info->attrs[DPLLA_SOURCE_TYPE]);
> +
> +	mutex_lock(&dpll->lock);
> +	ret = dpll->ops->set_source_type(dpll, src_id, type);
> +	mutex_unlock(&dpll->lock);
> +
> +	return ret;
> +}
> +
> +static int dpll_genl_cmd_set_output(struct param *p)
> +{
> +	const struct genl_dumpit_info *info = genl_dumpit_info(p->cb);
> +	struct dpll_device *dpll = p->dpll;
> +	int ret = 0, out_id, type;
> +
> +	if (!info->attrs[DPLLA_OUTPUT_ID] ||
> +	    !info->attrs[DPLLA_OUTPUT_TYPE])
> +		return -EINVAL;
> +
> +	if (!dpll->ops->set_output_type)
> +		return -EOPNOTSUPP;
> +
> +	out_id = nla_get_u32(info->attrs[DPLLA_OUTPUT_ID]);
> +	type = nla_get_u32(info->attrs[DPLLA_OUTPUT_TYPE]);
> +
> +	mutex_lock(&dpll->lock);
> +	ret = dpll->ops->set_source_type(dpll, out_id, type);
> +	mutex_unlock(&dpll->lock);
> +
> +	return ret;
> +}
> +
> +static int dpll_device_loop_cb(struct dpll_device *dpll, void *data)
> +{
> +	struct dpll_dump_ctx *ctx;
> +	struct param *p = (struct param *)data;
> +
> +	ctx = dpll_dump_context(p->cb);
> +
> +	ctx->pos_idx = dpll->id;
> +
> +	return dpll_device_dump_one(dpll, p->msg, ctx->flags);
> +}
> +
> +static int dpll_cmd_device_dump(struct param *p)
> +{
> +	struct dpll_dump_ctx *ctx = dpll_dump_context(p->cb);
> +
> +	return for_each_dpll_device(ctx->pos_idx, dpll_device_loop_cb, p);
> +}
> +
> +static int dpll_genl_cmd_device_get_id(struct param *p)
> +{
> +	struct dpll_device *dpll = p->dpll;
> +	int flags = 0;
> +
> +	if (p->attrs[DPLLA_FLAGS])
> +		flags = nla_get_u32(p->attrs[DPLLA_FLAGS]);
> +
> +	return dpll_device_dump_one(dpll, p->msg, flags);
> +}
> +
> +static cb_t cmd_doit_cb[] = {
> +	[DPLL_CMD_DEVICE_GET]		= dpll_genl_cmd_device_get_id,
> +	[DPLL_CMD_SET_SOURCE_TYPE]	= dpll_genl_cmd_set_source,
> +	[DPLL_CMD_SET_OUTPUT_TYPE]	= dpll_genl_cmd_set_output,
> +};
> +
> +static cb_t cmd_dump_cb[] = {
> +	[DPLL_CMD_DEVICE_GET]		= dpll_cmd_device_dump,
> +};
> +
> +static int dpll_genl_cmd_start(struct netlink_callback *cb)
> +{
> +	const struct genl_dumpit_info *info = genl_dumpit_info(cb);
> +	struct dpll_dump_ctx *ctx = dpll_dump_context(cb);
> +
> +	ctx->dev = NULL;
> +	if (info->attrs[DPLLA_FLAGS])
> +		ctx->flags = nla_get_u32(info->attrs[DPLLA_FLAGS]);
> +	else
> +		ctx->flags = 0;
> +	ctx->pos_idx = 0;
> +	ctx->pos_src_idx = 0;
> +	ctx->pos_out_idx = 0;
> +	return 0;
> +}
> +
> +static int dpll_genl_cmd_dumpit(struct sk_buff *skb,
> +				   struct netlink_callback *cb)
> +{
> +	struct param p = { .cb = cb, .msg = skb };
> +	const struct genl_dumpit_info *info = genl_dumpit_info(cb);
> +	int cmd = info->op.cmd;
> +	int ret;
> +	void *hdr;
> +
> +	hdr = genlmsg_put(skb, 0, 0, &dpll_gnl_family, 0, cmd);
> +	if (!hdr)
> +		return -EMSGSIZE;
> +
> +	ret = cmd_dump_cb[cmd](&p);
> +	if (ret)
> +		goto out_cancel_msg;
> +
> +	genlmsg_end(skb, hdr);
> +
> +	return 0;
> +
> +out_cancel_msg:
> +	genlmsg_cancel(skb, hdr);
> +
> +	return ret;
> +}
> +
> +static int dpll_genl_cmd_doit(struct sk_buff *skb,
> +				 struct genl_info *info)
> +{
> +	struct param p = { .attrs = info->attrs, .dpll = info->user_ptr[0] };
> +	int cmd = info->genlhdr->cmd;
> +	struct sk_buff *msg;
> +	void *hdr;
> +	int ret;
> +
> +	msg = genlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
> +	if (!msg)
> +		return -ENOMEM;
> +	p.msg = msg;
> +
> +	hdr = genlmsg_put_reply(msg, info, &dpll_gnl_family, 0, cmd);
> +	if (!hdr) {
> +		ret = -EMSGSIZE;
> +		goto out_free_msg;
> +	}
> +
> +	ret = cmd_doit_cb[cmd](&p);
> +	if (ret)
> +		goto out_cancel_msg;
> +
> +	genlmsg_end(msg, hdr);
> +
> +	return genlmsg_reply(msg, info);
> +
> +out_cancel_msg:
> +	genlmsg_cancel(msg, hdr);
> +out_free_msg:
> +	nlmsg_free(msg);
> +
> +	return ret;
> +}
> +
> +static int dpll_pre_doit(const struct genl_ops *ops, struct sk_buff *skb,
> +						 struct genl_info *info)
> +{
> +	struct dpll_device *dpll;
> +	int id;
> +
> +	if (!info->attrs[DPLLA_DEVICE_ID])
> +		return -EINVAL;
> +	id = nla_get_u32(info->attrs[DPLLA_DEVICE_ID]);
> +
> +	dpll = dpll_device_get_by_id(id);
> +	if (!dpll)
> +		return -ENODEV;
> +	info->user_ptr[0] = dpll;
> +
> +	return 0;
> +}
> +
> +static const struct genl_ops dpll_genl_ops[] = {
> +	{
> +		.cmd	= DPLL_CMD_DEVICE_GET,
> +		.start	= dpll_genl_cmd_start,
> +		.dumpit	= dpll_genl_cmd_dumpit,
> +		.doit	= dpll_genl_cmd_doit,
> +		.policy	= dpll_genl_get_policy,
> +		.maxattr = ARRAY_SIZE(dpll_genl_get_policy) - 1,
> +	},
> +	{
> +		.cmd	= DPLL_CMD_SET_SOURCE_TYPE,
> +		.flags	= GENL_UNS_ADMIN_PERM,
> +		.doit	= dpll_genl_cmd_doit,
> +		.policy	= dpll_genl_set_source_policy,
> +		.maxattr = ARRAY_SIZE(dpll_genl_set_source_policy) - 1,
> +	},
> +	{
> +		.cmd	= DPLL_CMD_SET_OUTPUT_TYPE,
> +		.flags	= GENL_UNS_ADMIN_PERM,
> +		.doit	= dpll_genl_cmd_doit,
> +		.policy	= dpll_genl_set_output_policy,
> +		.maxattr = ARRAY_SIZE(dpll_genl_set_output_policy) - 1,
> +	},
> +};
> +
> +static struct genl_family dpll_gnl_family __ro_after_init = {
> +	.hdrsize	= 0,
> +	.name		= DPLL_FAMILY_NAME,
> +	.version	= DPLL_VERSION,
> +	.ops		= dpll_genl_ops,
> +	.n_ops		= ARRAY_SIZE(dpll_genl_ops),
> +	.mcgrps		= dpll_genl_mcgrps,
> +	.n_mcgrps	= ARRAY_SIZE(dpll_genl_mcgrps),
> +	.pre_doit	= dpll_pre_doit,
> +};
> +
> +int __init dpll_netlink_init(void)
> +{
> +	return genl_register_family(&dpll_gnl_family);
> +}
> +
> +void dpll_netlink_finish(void)
> +{
> +	genl_unregister_family(&dpll_gnl_family);
> +}
> +
> +void __exit dpll_netlink_fini(void)
> +{
> +	dpll_netlink_finish();
> +}
> diff --git a/drivers/dpll/dpll_netlink.h b/drivers/dpll/dpll_netlink.h
> new file mode 100644
> index 000000000000..e2d100f59dd6
> --- /dev/null
> +++ b/drivers/dpll/dpll_netlink.h
> @@ -0,0 +1,7 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + *  Copyright (c) 2021 Meta Platforms, Inc. and affiliates
> + */
> +
> +int __init dpll_netlink_init(void);
> +void dpll_netlink_finish(void);
> diff --git a/include/linux/dpll.h b/include/linux/dpll.h
> new file mode 100644
> index 000000000000..9051337bcf9e
> --- /dev/null
> +++ b/include/linux/dpll.h
> @@ -0,0 +1,25 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + *  Copyright (c) 2021 Meta Platforms, Inc. and affiliates
> + */
> +
> +#ifndef __DPLL_H__
> +#define __DPLL_H__
> +
> +struct dpll_device;
> +
> +struct dpll_device_ops {
> +	int (*get_status)(struct dpll_device *dpll);
> +	int (*get_temp)(struct dpll_device *dpll);
> +	int (*get_lock_status)(struct dpll_device *dpll);
> +	int (*get_source_type)(struct dpll_device *dpll, int id);
> +	int (*get_output_type)(struct dpll_device *dpll, int id);
> +	int (*set_source_type)(struct dpll_device *dpll, int id, int val);
> +	int (*set_output_type)(struct dpll_device *dpll, int id, int val);
> +};
> +
> +struct dpll_device *dpll_device_alloc(struct dpll_device_ops *ops, int sources_count,
> +					 int outputs_count, void *priv);
> +void dpll_device_register(struct dpll_device *dpll);
> +void *dpll_priv(struct dpll_device *dpll);
> +#endif
> diff --git a/include/uapi/linux/dpll.h b/include/uapi/linux/dpll.h
> new file mode 100644
> index 000000000000..8c00f52736ee
> --- /dev/null
> +++ b/include/uapi/linux/dpll.h
> @@ -0,0 +1,77 @@
> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
> +#ifndef _UAPI_LINUX_DPLL_H
> +#define _UAPI_LINUX_DPLL_H
> +
> +#define DPLL_NAME_LENGTH	20
> +
> +/* Adding event notification support elements */
> +#define DPLL_FAMILY_NAME		"dpll"
> +#define DPLL_VERSION			0x01
> +#define DPLL_CONFIG_DEVICE_GROUP_NAME  "config"
> +#define DPLL_CONFIG_SOURCE_GROUP_NAME  "source"
> +#define DPLL_CONFIG_OUTPUT_GROUP_NAME  "output"
> +#define DPLL_MONITOR_GROUP_NAME        "monitor"
> +
> +#define DPLL_FLAG_SOURCES	1
> +#define DPLL_FLAG_OUTPUTS	2
> +#define DPLL_FLAG_STATUS	4
> +
> +/* Attributes of dpll_genl_family */
> +enum dpll_genl_get_attr {
> +	DPLLA_UNSPEC,
> +	DPLLA_DEVICE,
> +	DPLLA_DEVICE_ID,
> +	DPLLA_DEVICE_NAME,
> +	DPLLA_SOURCE,
> +	DPLLA_SOURCE_ID,
> +	DPLLA_SOURCE_TYPE,
> +	DPLLA_OUTPUT,
> +	DPLLA_OUTPUT_ID,
> +	DPLLA_OUTPUT_TYPE,
> +	DPLLA_STATUS,
> +	DPLLA_TEMP,
> +	DPLLA_LOCK_STATUS,
> +	DPLLA_FLAGS,
> +
> +	__DPLLA_MAX,
> +};
> +#define DPLLA_GET_MAX (__DPLLA_MAX - 1)

I think "_get_/_GET_" in above names is outdated?

> +
> +/* DPLL signal types used as source or as output */
> +enum dpll_genl_signal_type {
> +	DPLL_TYPE_EXT_1PPS,
> +	DPLL_TYPE_EXT_10MHZ,
> +	DPLL_TYPE_SYNCE_ETH_PORT,
> +	DPLL_TYPE_INT_OSCILLATOR,
> +	DPLL_TYPE_GNSS,
> +
> +	__DPLL_TYPE_MAX,
> +};
> +#define DPLL_TYPE_MAX (__DPLL_TYPE_MAX - 1)
> +
> +/* Events of dpll_genl_family */
> +enum dpll_genl_event {
> +	DPLL_EVENT_UNSPEC,
> +	DPLL_EVENT_DEVICE_CREATE,		/* DPLL device creation */
> +	DPLL_EVENT_DEVICE_DELETE,		/* DPLL device deletion */
> +	DPLL_EVENT_STATUS_LOCKED,		/* DPLL device locked to source */
> +	DPLL_EVENT_STATUS_UNLOCKED,	/* DPLL device freerun */
> +	DPLL_EVENT_SOURCE_CHANGE,		/* DPLL device source changed */
> +	DPLL_EVENT_OUTPUT_CHANGE,		/* DPLL device output changed */
> +
> +	__DPLL_EVENT_MAX,
> +};
> +#define DPLL_EVENT_MAX (__DPLL_EVENT_MAX - 1)
> +
> +/* Commands supported by the dpll_genl_family */
> +enum dpll_genl_cmd {
> +	DPLL_CMD_UNSPEC,
> +	DPLL_CMD_DEVICE_GET,	/* List of DPLL devices id */
> +	DPLL_CMD_SET_SOURCE_TYPE,	/* Set the DPLL device source type */
> +	DPLL_CMD_SET_OUTPUT_TYPE,	/* Get the DPLL device output type */

"Get" in comment description looks like a typo.
I am getting bit confused with the name and comments.
For me, first look says: it is selection of a type of a source.
But in the code I can see it selects a source id and a type.
Type of source originates in HW design, why would the one want to "set" it?
I can imagine a HW design where a single source or output would allow to choose
where the signal originates/goes, some kind of extra selector layer for a
source/output, but was that the intention?
If so, shouldn't the user get some bitmap/list of modes available for each
source/output?

The user shall get some extra information about the source/output. Right now
there can be multiple sources/outputs of the same type, but not really possible
to find out their purpose. I.e. a dpll equipped with four source of 
DPLL_TYPE_EXT_1PPS type.

This implementation looks like designed for a "forced reference lock" mode
where the user must explicitly select one source. But a multi source/output
DPLL could be running in different modes. I believe most important is automatic
mode, where it tries to lock to a user-configured source priority list.
However, there is also freerun mode, where dpll isn't even trying to lock to
anything, or NCO - Numerically Controlled Oscillator mode. 
It would be great to have ability to select DPLL modes, but also to be able to
configure priorities, read failure status, configure extra "features" (i.e.
Embedded Sync, EEC modes, Fast Lock).

The sources and outputs can also have some extra features or capabilities, like:
- enable Embedded Sync
- add phase delay
- configure frequency (user might need to use source/output with different
  frequency then 1 PPS or 10MHz)

Generally, for simple DPLL designs this interface could do the job (although,
I still think user needs more information about the sources/outputs), but for
more complex ones, there should be something different, which takes care of my
comments regarding extra configuration needed.

Thanks,
Arkadiusz

> +
> +	__DPLL_CMD_MAX,
> +};
> +#define DPLL_CMD_MAX (__DPLL_CMD_MAX - 1)
> +
> +#endif /* _UAPI_LINUX_DPLL_H */
> -- 
> 2.27.0
> 
>

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