wimax: basic API: kernel/user messaging, rfkill and reset

Implements the three basic operations provided by the stack's control
interface to WiMAX devices:

- Messaging channel between user space and driver/device

  This implements a direct communication channel between user space
  and the driver/device, by which free form messages can be sent back
  and forth.

  This is intended for device-specific features, vendor quirks, etc.

- RF-kill framework integration

  Provide most of the RF-Kill integration for WiMAX drivers so that
  all device drivers have to do is after wimax_dev_add() is call
  wimax_report_rfkill_{hw,sw}() to update initial state and then every
  time it changes.

  Provides wimax_rfkill() for the kernel to call to set software
  RF-Kill status and/or query current hardware and software switch
  status.

  Exports wimax_rfkill() over generic netlink to user space.

- Reset a WiMAX device

  Provides wimax_reset() for the kernel to reset a wimax device as
  needed and exports it over generic netlink to user space.

This API is clearly limited, as it still provides no way to do the
basic scan, connect and disconnect in a hardware independent way.  The
WiMAX case is more complex than WiFi due to the way networks are
discovered and provisioned.

The next developments are to add the basic operations so they can be
offerent by different drivers. However, we'd like to get more vendors
to jump in and provide feedback of how the user/kernel API/abstraction
layer should be.

The user space code for the i2400m, as of now, uses the messaging
channel, but that will change as the API evolves.
Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/wimax/op-reset.c

+/*
+ * Linux WiMAX
+ * Implement and export a method for resetting a WiMAX device
+ *
+ *
+ * Copyright (C) 2008 Intel Corporation <linux-wimax@intel.com>
+ * Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA.
+ *
+ *
+ * This implements a simple synchronous call to reset a WiMAX device.
+ *
+ * Resets aim at being warm, keeping the device handles active;
+ * however, when that fails, it falls back to a cold reset (that will
+ * disconnect and reconnect the device).
+ */
+
+#include <net/wimax.h>
+#include <net/genetlink.h>
+#include <linux/wimax.h>
+#include <linux/security.h>
+#include "wimax-internal.h"
+
+#define D_SUBMODULE op_reset
+#include "debug-levels.h"
+
+
+/**
+ * wimax_reset - Reset a WiMAX device
+ *
+ * @wimax_dev: WiMAX device descriptor
+ *
+ * Returns:
+ *
+ * %0 if ok and a warm reset was done (the device still exists in
+ * the system).
+ *
+ * -%ENODEV if a cold/bus reset had to be done (device has
+ * disconnected and reconnected, so current handle is not valid
+ * any more).
+ *
+ * -%EINVAL if the device is not even registered.
+ *
+ * Any other negative error code shall be considered as
+ * non-recoverable.
+ *
+ * Description:
+ *
+ * Called when wanting to reset the device for any reason. Device is
+ * taken back to power on status.
+ *
+ * This call blocks; on succesful return, the device has completed the
+ * reset process and is ready to operate.
+ */
+int wimax_reset(struct wimax_dev *wimax_dev)
+{
+	int result = -EINVAL;
+	struct device *dev = wimax_dev_to_dev(wimax_dev);
+	enum wimax_st state;
+
+	might_sleep();
+	d_fnstart(3, dev, "(wimax_dev %p)\n", wimax_dev);
+	mutex_lock(&wimax_dev->mutex);
+	dev_hold(wimax_dev->net_dev);
+	state = wimax_dev->state;
+	mutex_unlock(&wimax_dev->mutex);
+
+	if (state >= WIMAX_ST_DOWN) {
+		mutex_lock(&wimax_dev->mutex_reset);
+		result = wimax_dev->op_reset(wimax_dev);
+		mutex_unlock(&wimax_dev->mutex_reset);
+	}
+	dev_put(wimax_dev->net_dev);
+
+	d_fnend(3, dev, "(wimax_dev %p) = %d\n", wimax_dev, result);
+	return result;
+}
+EXPORT_SYMBOL(wimax_reset);
+
+
+static const
+struct nla_policy wimax_gnl_reset_policy[WIMAX_GNL_ATTR_MAX + 1] = {
+	[WIMAX_GNL_RESET_IFIDX] = {
+		.type = NLA_U32,
+	},
+};
+
+
+/*
+ * Exporting to user space over generic netlink
+ *
+ * Parse the reset command from user space, return error code.
+ *
+ * No attributes.
+ */
+static
+int wimax_gnl_doit_reset(struct sk_buff *skb, struct genl_info *info)
+{
+	int result, ifindex;
+	struct wimax_dev *wimax_dev;
+	struct device *dev;
+
+	d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
+	result = -ENODEV;
+	if (info->attrs[WIMAX_GNL_RESET_IFIDX] == NULL) {
+		printk(KERN_ERR "WIMAX_GNL_OP_RFKILL: can't find IFIDX "
+			"attribute\n");
+		goto error_no_wimax_dev;
+	}
+	ifindex = nla_get_u32(info->attrs[WIMAX_GNL_RESET_IFIDX]);
+	wimax_dev = wimax_dev_get_by_genl_info(info, ifindex);
+	if (wimax_dev == NULL)
+		goto error_no_wimax_dev;
+	dev = wimax_dev_to_dev(wimax_dev);
+	/* Execute the operation and send the result back to user space */
+	result = wimax_reset(wimax_dev);
+	dev_put(wimax_dev->net_dev);
+error_no_wimax_dev:
+	d_fnend(3, NULL, "(skb %p info %p) = %d\n", skb, info, result);
+	return result;
+}
+
+
+struct genl_ops wimax_gnl_reset = {
+	.cmd = WIMAX_GNL_OP_RESET,
+	.flags = GENL_ADMIN_PERM,
+	.policy = wimax_gnl_reset_policy,
+	.doit = wimax_gnl_doit_reset,
+	.dumpit = NULL,
+};