[patch 1/2] add support for generic actuator devices

[Jiri Pirko]

Introduce support for generic actuator devices. Each device is
identified by bus_name, dev_name and index. First two are derived
according to the bus and address of the parent device. For example
"usb/1-2/". The last one is defined by driver itself. That is for cases
where it has multiple actuator devices connected via single parent.

Each driver registers actuators one by one. For each instance, ops are
defined. Currently there are 3 ops supported:
-status - called by core to driver in order to get actual actuator status
-move - called to initiate the movement of an actuator
-stop - called to stop the movement if any

A generic Netlink interface is exposed to userspace. It allows to get
actuator status, dump all available actuator devices, iniatiate move and
stop of an actuator. Also the netlink interface is used to send events
to userspace in case driver notifies core about status change.

libactuator project is there to provide generic Netlink wrapper and
custom util to manipulate actuators:
https://git.kernel.org/pub/scm/linux/kernel/git/jpirko/libactuator.git/

Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxxx>
---
 MAINTAINERS                   |   7 +
 drivers/Kconfig               |   2 +
 drivers/Makefile              |   1 +
 drivers/actuator/Kconfig      |  15 ++
 drivers/actuator/Makefile     |   1 +
 drivers/actuator/actuator.c   | 410 ++++++++++++++++++++++++++++++++++++++++++
 include/linux/actuator.h      |  43 +++++
 include/uapi/linux/actuator.h |  74 ++++++++
 8 files changed, 553 insertions(+)
 create mode 100644 drivers/actuator/Kconfig
 create mode 100644 drivers/actuator/Makefile
 create mode 100644 drivers/actuator/actuator.c
 create mode 100644 include/linux/actuator.h
 create mode 100644 include/uapi/linux/actuator.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 1347726..029795a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5671,6 +5671,13 @@ W:	https://linuxtv.org
 S:	Maintained
 F:	drivers/media/radio/radio-gemtek*
 
+GENERIC ACTUATOR SUPPORT
+M:	Jiri Pirko <jiri@xxxxxxxxxxx>
+L:	linux-kernel@xxxxxxxxxxxxxxx
+S:	Maintained
+F:	drivers/actuator/
+F:	include/linux/actuator.h
+
 GENERIC GPIO I2C DRIVER
 M:	Haavard Skinnemoen <hskinnemoen@xxxxxxxxx>
 S:	Supported
diff --git a/drivers/Kconfig b/drivers/Kconfig
index 505c676..7617173 100644
--- a/drivers/Kconfig
+++ b/drivers/Kconfig
@@ -208,4 +208,6 @@ source "drivers/tee/Kconfig"
 
 source "drivers/mux/Kconfig"
 
+source "drivers/actuator/Kconfig"
+
 endmenu
diff --git a/drivers/Makefile b/drivers/Makefile
index dfdcda0..35e0e55 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -182,3 +182,4 @@ obj-$(CONFIG_FPGA)		+= fpga/
 obj-$(CONFIG_FSI)		+= fsi/
 obj-$(CONFIG_TEE)		+= tee/
 obj-$(CONFIG_MULTIPLEXER)	+= mux/
+obj-$(CONFIG_ACTUATOR)		+= actuator/
diff --git a/drivers/actuator/Kconfig b/drivers/actuator/Kconfig
new file mode 100644
index 0000000..6deac93
--- /dev/null
+++ b/drivers/actuator/Kconfig
@@ -0,0 +1,15 @@
+menuconfig ACTUATOR
+	tristate "Generic actuator support"
+	depends on NET
+	---help---
+	  This provides a support for generic actuator devices. For example
+	  all sorts of linear and rotary actuators.
+
+	  If you want this support, you should say Y here.
+
+	  This support can also be built as a module.  If so, the module
+	  will be called actuator.
+
+if ACTUATOR
+
+endif
diff --git a/drivers/actuator/Makefile b/drivers/actuator/Makefile
new file mode 100644
index 0000000..c45af36
--- /dev/null
+++ b/drivers/actuator/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_ACTUATOR)		+= actuator.o
diff --git a/drivers/actuator/actuator.c b/drivers/actuator/actuator.c
new file mode 100644
index 0000000..ce8a587
--- /dev/null
+++ b/drivers/actuator/actuator.c
@@ -0,0 +1,410 @@
+/*
+ * drivers/actuator/actuator.c - Generic actuator support
+ * Copyright (c) 2016-2017 Jiri Pirko <jiri@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/list.h>
+#include <linux/mutex.h>
+#include <linux/types.h>
+#include <net/genetlink.h>
+#include <net/netlink.h>
+#include <uapi/linux/actuator.h>
+#include <linux/actuator.h>
+
+static LIST_HEAD(actuator_list);
+static DEFINE_MUTEX(actuator_mutex);
+
+struct actuator {
+	struct list_head list;
+	struct device *dev;
+	unsigned int index;
+	const struct actuator_ops *aco;
+	unsigned long priv[0];
+};
+
+void *actuator_priv(struct actuator *act)
+{
+	return act->priv;
+}
+EXPORT_SYMBOL_GPL(actuator_priv);
+
+static struct genl_family actuator_nl_family;
+
+enum actuator_multicast_groups {
+	ACTUATOR_MCGRP_CONFIG,
+};
+
+static const struct genl_multicast_group actuator_nl_mcgrps[] = {
+	[ACTUATOR_MCGRP_CONFIG] = { .name = ACTUATOR_GENL_MCGRP_CONFIG_NAME },
+};
+
+static int actuator_nl_put_handle(struct sk_buff *msg, struct actuator *act)
+{
+	if (nla_put_string(msg, ACTUATOR_ATTR_BUS_NAME, act->dev->bus->name))
+		return -EMSGSIZE;
+	if (nla_put_string(msg, ACTUATOR_ATTR_DEV_NAME, dev_name(act->dev)))
+		return -EMSGSIZE;
+	if (nla_put_u32(msg, ACTUATOR_ATTR_INDEX, act->index))
+		return -EMSGSIZE;
+	return 0;
+}
+
+static int actuator_nl_fill(struct sk_buff *msg, struct actuator *act,
+			    enum actuator_command cmd,
+			    struct actuator_status *status, bool fill_status,
+			    u32 portid, u32 seq, int flags)
+{
+	void *hdr;
+
+	if (!status && fill_status) {
+		struct actuator_status tmp_status;
+		int err;
+
+		err = act->aco->status(act, &tmp_status);
+		if (err)
+			return err;
+		status = &tmp_status;
+	}
+
+	hdr = genlmsg_put(msg, portid, seq, &actuator_nl_family, flags, cmd);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (actuator_nl_put_handle(msg, act))
+		goto nla_put_failure;
+	if (nla_put_string(msg, ACTUATOR_ATTR_DRIVER_NAME,
+			   act->aco->driver_name))
+		goto nla_put_failure;
+	if (nla_put_u8(msg, ACTUATOR_ATTR_TYPE, act->aco->type))
+		goto nla_put_failure;
+	if (nla_put_u8(msg, ACTUATOR_ATTR_UNITS, act->aco->units))
+		goto nla_put_failure;
+	if (fill_status) {
+		if (nla_put_u32(msg, ACTUATOR_ATTR_VALUE, status->value))
+			goto nla_put_failure;
+		if (nla_put_u8(msg, ACTUATOR_ATTR_MOVE_STATE,
+			       status->move_state))
+			goto nla_put_failure;
+	}
+
+	genlmsg_end(msg, hdr);
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+static void actuator_notify(struct actuator *act, enum actuator_command cmd,
+			    struct actuator_status *status, bool fill_status)
+{
+	struct sk_buff *msg;
+	int err;
+
+	WARN_ON(cmd != ACTUATOR_CMD_GET &&
+		cmd != ACTUATOR_CMD_NEW &&
+		cmd != ACTUATOR_CMD_DEL);
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg) {
+		dev_err(act->dev, "Failed to allocate actuator notification message\n");
+		return;
+	}
+
+	err = actuator_nl_fill(msg, act, cmd, status, fill_status, 0, 0, 0);
+	if (err) {
+		dev_err(act->dev, "Failed to fill-up actuator notification message\n");
+		nlmsg_free(msg);
+		return;
+	}
+
+	genlmsg_multicast(&actuator_nl_family, msg, 0,
+			  ACTUATOR_MCGRP_CONFIG, GFP_KERNEL);
+}
+
+/**
+ *	actuator_notify_status - Send actuator notifications
+ *
+ *	@act: actuator
+ *	@status: status
+ *
+ *	Called by the driver to notify about async status change.
+ */
+void actuator_notify_status(struct actuator *act,
+			    struct actuator_status *status)
+{
+	actuator_notify(act, ACTUATOR_CMD_GET, status, true);
+}
+EXPORT_SYMBOL_GPL(actuator_notify_status);
+
+static void actuator_notify_new(struct actuator *act)
+{
+	actuator_notify(act, ACTUATOR_CMD_NEW, NULL, true);
+}
+
+static void actuator_notify_del(struct actuator *act)
+{
+	actuator_notify(act, ACTUATOR_CMD_DEL, NULL, false);
+}
+
+static int actuator_nl_cmd_get_doit(struct sk_buff *skb, struct genl_info *info)
+{
+	struct actuator *act = info->user_ptr[0];
+	struct sk_buff *msg;
+	int err;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return -ENOMEM;
+
+	err = actuator_nl_fill(msg, act, ACTUATOR_CMD_GET, NULL, true,
+			       info->snd_portid, info->snd_seq, 0);
+	if (err) {
+		nlmsg_free(msg);
+		return err;
+	}
+
+	return genlmsg_reply(msg, info);
+}
+
+static int actuator_nl_cmd_get_dumpit(struct sk_buff *msg,
+				      struct netlink_callback *cb)
+{
+	struct actuator *act;
+	int start = cb->args[0];
+	int idx = 0;
+	int err;
+
+	mutex_lock(&actuator_mutex);
+	list_for_each_entry(act, &actuator_list, list) {
+		if (idx < start) {
+			idx++;
+			continue;
+		}
+		err = actuator_nl_fill(msg, act, ACTUATOR_CMD_GET, NULL, true,
+				       NETLINK_CB(cb->skb).portid,
+				       cb->nlh->nlmsg_seq, NLM_F_MULTI);
+		if (err)
+			goto out;
+		idx++;
+	}
+out:
+	mutex_unlock(&actuator_mutex);
+
+	cb->args[0] = idx;
+	return msg->len;
+}
+
+static int actuator_nl_cmd_move_doit(struct sk_buff *skb,
+				     struct genl_info *info)
+{
+	struct actuator *act = info->user_ptr[0];
+	u32 value;
+
+	if (!info->attrs[ACTUATOR_ATTR_VALUE])
+		return -EINVAL;
+
+	value = nla_get_u32(info->attrs[ACTUATOR_ATTR_VALUE]);
+	if (act->aco->move)
+		return act->aco->move(act, value);
+	return -EOPNOTSUPP;
+}
+
+static int actuator_nl_cmd_stop_doit(struct sk_buff *skb,
+				     struct genl_info *info)
+{
+	struct actuator *act = info->user_ptr[0];
+
+	if (act->aco->stop)
+		return act->aco->stop(act);
+	return -EOPNOTSUPP;
+}
+
+static struct actuator *actuator_get_from_attrs(struct net *net,
+						struct nlattr **attrs)
+{
+	struct actuator *act;
+	char *busname;
+	char *devname;
+	u32 index;
+
+	if (!attrs[ACTUATOR_ATTR_BUS_NAME] ||
+	    !attrs[ACTUATOR_ATTR_DEV_NAME] ||
+	    !attrs[ACTUATOR_ATTR_INDEX])
+		return ERR_PTR(-EINVAL);
+
+	busname = nla_data(attrs[ACTUATOR_ATTR_BUS_NAME]);
+	devname = nla_data(attrs[ACTUATOR_ATTR_DEV_NAME]);
+	index = nla_get_u32(attrs[ACTUATOR_ATTR_INDEX]);
+
+	list_for_each_entry(act, &actuator_list, list) {
+		if (strcmp(act->dev->bus->name, busname) == 0 &&
+		    strcmp(dev_name(act->dev), devname) == 0 &&
+		    act->index == index)
+			return act;
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+
+static struct actuator *actuator_get_from_info(struct genl_info *info)
+{
+	return actuator_get_from_attrs(genl_info_net(info), info->attrs);
+}
+
+static int actuator_nl_pre_doit(const struct genl_ops *ops,
+				struct sk_buff *skb, struct genl_info *info)
+{
+	struct actuator *act;
+
+	mutex_lock(&actuator_mutex);
+	act = actuator_get_from_info(info);
+	if (IS_ERR(act)) {
+		mutex_unlock(&actuator_mutex);
+		return PTR_ERR(act);
+	}
+	info->user_ptr[0] = act;
+	return 0;
+}
+
+static void actuator_nl_post_doit(const struct genl_ops *ops,
+				  struct sk_buff *skb, struct genl_info *info)
+{
+	mutex_unlock(&actuator_mutex);
+}
+
+static const struct nla_policy actuator_nl_policy[ACTUATOR_ATTR_MAX + 1] = {
+	[ACTUATOR_ATTR_BUS_NAME] = { .type = NLA_NUL_STRING },
+	[ACTUATOR_ATTR_DEV_NAME] = { .type = NLA_NUL_STRING },
+	[ACTUATOR_ATTR_INDEX] = { .type = NLA_U32 },
+	[ACTUATOR_ATTR_VALUE] = { .type = NLA_U32 },
+};
+
+static const struct genl_ops actuator_nl_ops[] = {
+	{
+		.cmd = ACTUATOR_CMD_GET,
+		.doit = actuator_nl_cmd_get_doit,
+		.dumpit = actuator_nl_cmd_get_dumpit,
+		.policy = actuator_nl_policy,
+		/* can be retrieved by unprivileged users */
+	},
+	{
+		.cmd = ACTUATOR_CMD_MOVE,
+		.doit = actuator_nl_cmd_move_doit,
+		.policy = actuator_nl_policy,
+		.flags = GENL_ADMIN_PERM,
+	},
+	{
+		.cmd = ACTUATOR_CMD_STOP,
+		.doit = actuator_nl_cmd_stop_doit,
+		.policy = actuator_nl_policy,
+		.flags = GENL_ADMIN_PERM,
+	},
+};
+
+static struct genl_family actuator_nl_family __ro_after_init = {
+	.name		= ACTUATOR_GENL_NAME,
+	.version	= ACTUATOR_GENL_VERSION,
+	.maxattr	= ACTUATOR_ATTR_MAX,
+	.pre_doit	= actuator_nl_pre_doit,
+	.post_doit	= actuator_nl_post_doit,
+	.module		= THIS_MODULE,
+	.ops		= actuator_nl_ops,
+	.n_ops		= ARRAY_SIZE(actuator_nl_ops),
+	.mcgrps		= actuator_nl_mcgrps,
+	.n_mcgrps	= ARRAY_SIZE(actuator_nl_mcgrps),
+};
+
+/**
+ *	actuator_alloc - Allocate new actuator instance resources
+ *
+ *	@aco: actuator instance ops
+ *
+ *	Allocate new actuator instance resources.
+ */
+struct actuator *actuator_alloc(const struct actuator_ops *aco)
+{
+	struct actuator *act;
+
+	WARN_ON(!aco->status || !aco->driver_name ||
+		aco->type == ACTUATOR_TYPE_UNSPEC ||
+		aco->units == ACTUATOR_UNITS_UNSPEC);
+	act = kzalloc(sizeof(struct actuator) + aco->priv_size, GFP_KERNEL);
+	if (!act)
+		return NULL;
+	act->aco = aco;
+	return act;
+}
+EXPORT_SYMBOL_GPL(actuator_alloc);
+
+/**
+ *	actuator_free - Free actuator instance resources
+ *
+ *	@act: actuator
+ */
+void actuator_free(struct actuator *act)
+{
+	kfree(act);
+}
+EXPORT_SYMBOL_GPL(actuator_free);
+
+/**
+ *	actuator_register - Register actuator instance
+ *
+ *	@act: actuator
+ *	@dev: parent device
+ *	@index: index within the parent device
+ */
+int actuator_register(struct actuator *act, struct device *dev,
+		      unsigned int index)
+{
+	act->dev = dev;
+	act->index = index;
+	mutex_lock(&actuator_mutex);
+	list_add_tail(&act->list, &actuator_list);
+	mutex_unlock(&actuator_mutex);
+	actuator_notify_new(act);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(actuator_register);
+
+/**
+ *	actuator_unregister - Unregister actuator instance
+ *
+ *	@act: actuator
+ */
+void actuator_unregister(struct actuator *act)
+{
+	mutex_lock(&actuator_mutex);
+	list_del(&act->list);
+	mutex_unlock(&actuator_mutex);
+	actuator_notify_del(act);
+}
+EXPORT_SYMBOL_GPL(actuator_unregister);
+
+static int __init actuator_init(void)
+{
+	return genl_register_family(&actuator_nl_family);
+}
+
+static void __exit actuator_exit(void)
+{
+	genl_unregister_family(&actuator_nl_family);
+}
+
+module_init(actuator_init);
+module_exit(actuator_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Jiri Pirko <jiri@xxxxxxxxxxx>");
+MODULE_DESCRIPTION("Generic actuator support");
+MODULE_ALIAS_GENL_FAMILY(ACTUATOR_GENL_NAME);
diff --git a/include/linux/actuator.h b/include/linux/actuator.h
new file mode 100644
index 0000000..4086885
--- /dev/null
+++ b/include/linux/actuator.h
@@ -0,0 +1,43 @@
+/*
+ * include/linux/actuator.h - Generic actuator support
+ * Copyright (c) 2016-2017 Jiri Pirko <jiri@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef _ACTUATOR_H_
+#define _ACTUATOR_H_
+
+#include <linux/types.h>
+#include <uapi/linux/actuator.h>
+
+struct actuator;
+
+struct actuator_status {
+	u32 value;
+	enum actuator_move_state move_state;
+};
+
+struct actuator_ops {
+	size_t priv_size;
+	const char *driver_name;
+	enum actuator_type type;
+	enum actuator_units units;
+	int (*status)(struct actuator *act, struct actuator_status *status);
+	int (*move)(struct actuator *act, u32 value);
+	int (*stop)(struct actuator *act);
+};
+
+void actuator_notify_status(struct actuator *act,
+			    struct actuator_status *status);
+void *actuator_priv(struct actuator *act);
+struct actuator *actuator_alloc(const struct actuator_ops *aco);
+void actuator_free(struct actuator *act);
+int actuator_register(struct actuator *act, struct device *dev,
+		      unsigned int index);
+void actuator_unregister(struct actuator *act);
+
+#endif
diff --git a/include/uapi/linux/actuator.h b/include/uapi/linux/actuator.h
new file mode 100644
index 0000000..4e2d958
--- /dev/null
+++ b/include/uapi/linux/actuator.h
@@ -0,0 +1,74 @@
+/*
+ * include/uapi/linux/actuator.h - Generic actuator support
+ * Copyright (c) 2017 Jiri Pirko <jiri@xxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#ifndef _UAPI_LINUX_ACTUATOR_H_
+#define _UAPI_LINUX_ACTUATOR_H_
+
+#define ACTUATOR_GENL_NAME "actuator"
+#define ACTUATOR_GENL_VERSION 0x1
+#define ACTUATOR_GENL_MCGRP_CONFIG_NAME "config"
+
+enum actuator_command {
+	/* don't change the order or add anything between, this is ABI! */
+	ACTUATOR_CMD_UNSPEC,
+
+	ACTUATOR_CMD_GET,		/* can dump */
+	ACTUATOR_CMD_NEW,
+	ACTUATOR_CMD_DEL,
+
+	ACTUATOR_CMD_MOVE,
+	ACTUATOR_CMD_STOP,
+
+	/* add new commands above here */
+	__ACTUATOR_CMD_MAX,
+	ACTUATOR_CMD_MAX = __ACTUATOR_CMD_MAX - 1
+};
+
+enum actuator_type {
+	ACTUATOR_TYPE_UNSPEC,
+	ACTUATOR_TYPE_LINEAR,
+};
+
+enum actuator_units {
+	ACTUATOR_UNITS_UNSPEC,
+	ACTUATOR_UNITS_UM, /* micrometres */
+};
+
+enum actuator_move_state {
+	ACTUATOR_MOVE_STATE_UNSPEC,
+	ACTUATOR_MOVE_STATE_STOPPED,
+	ACTUATOR_MOVE_STATE_POSITIVE,
+	ACTUATOR_MOVE_STATE_NEGATIVE,
+};
+
+enum actuator_attr {
+	/* don't change the order or add anything between, this is ABI! */
+	ACTUATOR_ATTR_UNSPEC,
+
+	/* bus name + dev name + index together are a handle
+	 * for actuator entity
+	 */
+	ACTUATOR_ATTR_BUS_NAME,		/* string */
+	ACTUATOR_ATTR_DEV_NAME,		/* string */
+	ACTUATOR_ATTR_INDEX,		/* u32 */
+
+	ACTUATOR_ATTR_DRIVER_NAME,	/* string */
+	ACTUATOR_ATTR_TYPE,		/* u8, enum actuator_type */
+	ACTUATOR_ATTR_UNITS,		/* u8, enum actuator_units */
+	ACTUATOR_ATTR_VALUE,		/* u32, in units */
+	ACTUATOR_ATTR_MOVE_STATE,	/* u8, enum actuator_move_state */
+
+	/* add new attributes above here, update the policy in actuator.c */
+
+	__ACTUATOR_ATTR_MAX,
+	ACTUATOR_ATTR_MAX = __ACTUATOR_ATTR_MAX - 1
+};
+
+#endif /* _UAPI_LINUX_ACTUATOR_H_ */
-- 
2.9.3