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>

1 files changed, 421 insertions, 0 deletions

diff --git a/net/wimax/op-msg.c b/net/wimax/op-msg.c
new file mode 100644
index 000000000000..cb3b4ad53683
--- /dev/null
+++ b/net/wimax/op-msg.c
@@ -0,0 +1,421 @@
+/*
+ * Linux WiMAX
+ * Generic messaging interface between userspace and driver/device
+ *
+ *
+ * Copyright (C) 2007-2008 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 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.
+ *
+ * See include/net/wimax.h
+ *
+ * GENERIC NETLINK ENCODING AND CAPACITY
+ *
+ * A destination "pipe name" is added to each message; it is up to the
+ * drivers to assign or use those names (if using them at all).
+ *
+ * Messages are encoded as a binary netlink attribute using nla_put()
+ * using type NLA_UNSPEC (as some versions of libnl still in
+ * deployment don't yet understand NLA_BINARY).
+ *
+ * The maximum capacity of this transport is PAGESIZE per message (so
+ * the actual payload will be bit smaller depending on the
+ * netlink/generic netlink attributes and headers).
+ *
+ * RECEPTION OF MESSAGES
+ *
+ * When a message is received from user space, it is passed verbatim
+ * to the driver calling wimax_dev->op_msg_from_user(). The return
+ * value from this function is passed back to user space as an ack
+ * over the generic netlink protocol.
+ *
+ * The stack doesn't do any processing or interpretation of these
+ * messages.
+ *
+ * SENDING MESSAGES
+ *
+ * Messages can be sent with wimax_msg().
+ *
+ * If the message delivery needs to happen on a different context to
+ * that of its creation, wimax_msg_alloc() can be used to get a
+ * pointer to the message that can be delivered later on with
+ * wimax_msg_send().
+ *
+ * ROADMAP
+ *
+ * wimax_gnl_doit_msg_from_user()    Process a message from user space
+ *   wimax_dev_get_by_genl_info()
+ *   wimax_dev->op_msg_from_user()   Delivery of message to the driver
+ *
+ * wimax_msg()                       Send a message to user space
+ *   wimax_msg_alloc()
+ *   wimax_msg_send()
+ */
+#include <linux/device.h>
+#include <net/genetlink.h>
+#include <linux/netdevice.h>
+#include <linux/wimax.h>
+#include <linux/security.h>
+#include "wimax-internal.h"
+
+
+#define D_SUBMODULE op_msg
+#include "debug-levels.h"
+
+
+/**
+ * wimax_msg_alloc - Create a new skb for sending a message to userspace
+ *
+ * @wimax_dev: WiMAX device descriptor
+ * @pipe_name: "named pipe" the message will be sent to
+ * @msg: pointer to the message data to send
+ * @size: size of the message to send (in bytes), including the header.
+ * @gfp_flags: flags for memory allocation.
+ *
+ * Returns: %0 if ok, negative errno code on error
+ *
+ * Description:
+ *
+ * Allocates an skb that will contain the message to send to user
+ * space over the messaging pipe and initializes it, copying the
+ * payload.
+ *
+ * Once this call is done, you can deliver it with
+ * wimax_msg_send().
+ *
+ * IMPORTANT:
+ *
+ * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
+ * wimax_msg_send() depends on skb->data being placed at the
+ * beginning of the user message.
+ */
+struct sk_buff *wimax_msg_alloc(struct wimax_dev *wimax_dev,
+                                const char *pipe_name,
+                                const void *msg, size_t size,
+                                gfp_t gfp_flags)
+{
+        int result;
+        struct device *dev = wimax_dev->net_dev->dev.parent;
+        size_t msg_size;
+        void *genl_msg;
+        struct sk_buff *skb;
+
+        msg_size = nla_total_size(size)
+                + nla_total_size(sizeof(u32))
+                + (pipe_name ? nla_total_size(strlen(pipe_name)) : 0);
+        result = -ENOMEM;
+        skb = genlmsg_new(msg_size, gfp_flags);
+        if (skb == NULL)
+                goto error_new;
+        genl_msg = genlmsg_put(skb, 0, 0, &wimax_gnl_family,
+                               0, WIMAX_GNL_OP_MSG_TO_USER);
+        if (genl_msg == NULL) {
+                dev_err(dev, "no memory to create generic netlink message\n");
+                goto error_genlmsg_put;
+        }
+        result = nla_put_u32(skb, WIMAX_GNL_MSG_IFIDX,
+                             wimax_dev->net_dev->ifindex);
+        if (result < 0) {
+                dev_err(dev, "no memory to add ifindex attribute\n");
+                goto error_nla_put;
+        }
+        if (pipe_name) {
+                result = nla_put_string(skb, WIMAX_GNL_MSG_PIPE_NAME,
+                                        pipe_name);
+                if (result < 0) {
+                        dev_err(dev, "no memory to add pipe_name attribute\n");
+                        goto error_nla_put;
+                }
+        }
+        result = nla_put(skb, WIMAX_GNL_MSG_DATA, size, msg);
+        if (result < 0) {
+                dev_err(dev, "no memory to add payload in attribute\n");
+                goto error_nla_put;
+        }
+        genlmsg_end(skb, genl_msg);
+        return skb;
+
+error_nla_put:
+error_genlmsg_put:
+error_new:
+        nlmsg_free(skb);
+        return ERR_PTR(result);
+
+}
+EXPORT_SYMBOL_GPL(wimax_msg_alloc);
+
+
+/**
+ * wimax_msg_data_len - Return a pointer and size of a message's payload
+ *
+ * @msg: Pointer to a message created with wimax_msg_alloc()
+ * @size: Pointer to where to store the message's size
+ *
+ * Returns the pointer to the message data.
+ */
+const void *wimax_msg_data_len(struct sk_buff *msg, size_t *size)
+{
+        struct nlmsghdr *nlh = (void *) msg->head;
+        struct nlattr *nla;
+
+        nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
+                              WIMAX_GNL_MSG_DATA);
+        if (nla == NULL) {
+                printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
+                return NULL;
+        }
+        *size = nla_len(nla);
+        return nla_data(nla);
+}
+EXPORT_SYMBOL_GPL(wimax_msg_data_len);
+
+
+/**
+ * wimax_msg_data - Return a pointer to a message's payload
+ *
+ * @msg: Pointer to a message created with wimax_msg_alloc()
+ */
+const void *wimax_msg_data(struct sk_buff *msg)
+{
+        struct nlmsghdr *nlh = (void *) msg->head;
+        struct nlattr *nla;
+
+        nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
+                              WIMAX_GNL_MSG_DATA);
+        if (nla == NULL) {
+                printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
+                return NULL;
+        }
+        return nla_data(nla);
+}
+EXPORT_SYMBOL_GPL(wimax_msg_data);
+
+
+/**
+ * wimax_msg_len - Return a message's payload length
+ *
+ * @msg: Pointer to a message created with wimax_msg_alloc()
+ */
+ssize_t wimax_msg_len(struct sk_buff *msg)
+{
+        struct nlmsghdr *nlh = (void *) msg->head;
+        struct nlattr *nla;
+
+        nla = nlmsg_find_attr(nlh, sizeof(struct genlmsghdr),
+                              WIMAX_GNL_MSG_DATA);
+        if (nla == NULL) {
+                printk(KERN_ERR "Cannot find attribute WIMAX_GNL_MSG_DATA\n");
+                return -EINVAL;
+        }
+        return nla_len(nla);
+}
+EXPORT_SYMBOL_GPL(wimax_msg_len);
+
+
+/**
+ * wimax_msg_send - Send a pre-allocated message to user space
+ *
+ * @wimax_dev: WiMAX device descriptor
+ *
+ * @skb: &struct sk_buff returned by wimax_msg_alloc(). Note the
+ *     ownership of @skb is transferred to this function.
+ *
+ * Returns: 0 if ok, < 0 errno code on error
+ *
+ * Description:
+ *
+ * Sends a free-form message that was preallocated with
+ * wimax_msg_alloc() and filled up.
+ *
+ * Assumes that once you pass an skb to this function for sending, it
+ * owns it and will release it when done (on success).
+ *
+ * IMPORTANT:
+ *
+ * Don't use skb_push()/skb_pull()/skb_reserve() on the skb, as
+ * wimax_msg_send() depends on skb->data being placed at the
+ * beginning of the user message.
+ */
+int wimax_msg_send(struct wimax_dev *wimax_dev, struct sk_buff *skb)
+{
+        int result;
+        struct device *dev = wimax_dev->net_dev->dev.parent;
+        void *msg = skb->data;
+        size_t size = skb->len;
+        might_sleep();
+
+        d_printf(1, dev, "CTX: wimax msg, %zu bytes\n", size);
+        d_dump(2, dev, msg, size);
+        result = genlmsg_multicast(skb, 0, wimax_gnl_mcg.id, GFP_KERNEL);
+        d_printf(1, dev, "CTX: genl multicast result %d\n", result);
+        if (result == -ESRCH)   /* Nobody connected, ignore it */
+                result = 0;     /* btw, the skb is freed already */
+        return result;
+}
+EXPORT_SYMBOL_GPL(wimax_msg_send);
+
+
+/**
+ * wimax_msg - Send a message to user space
+ *
+ * @wimax_dev: WiMAX device descriptor (properly referenced)
+ * @pipe_name: "named pipe" the message will be sent to
+ * @buf: pointer to the message to send.
+ * @size: size of the buffer pointed to by @buf (in bytes).
+ * @gfp_flags: flags for memory allocation.
+ *
+ * Returns: %0 if ok, negative errno code on error.
+ *
+ * Description:
+ *
+ * Sends a free-form message to user space on the device @wimax_dev.
+ *
+ * NOTES:
+ *
+ * Once the @skb is given to this function, who will own it and will
+ * release it when done (unless it returns error).
+ */
+int wimax_msg(struct wimax_dev *wimax_dev, const char *pipe_name,
+              const void *buf, size_t size, gfp_t gfp_flags)
+{
+        int result = -ENOMEM;
+        struct sk_buff *skb;
+
+        skb = wimax_msg_alloc(wimax_dev, pipe_name, buf, size, gfp_flags);
+        if (skb == NULL)
+                goto error_msg_new;
+        result = wimax_msg_send(wimax_dev, skb);
+error_msg_new:
+        return result;
+}
+EXPORT_SYMBOL_GPL(wimax_msg);
+
+
+static const
+struct nla_policy wimax_gnl_msg_policy[WIMAX_GNL_ATTR_MAX + 1] = {
+        [WIMAX_GNL_MSG_IFIDX] = {
+                .type = NLA_U32,
+        },
+        [WIMAX_GNL_MSG_DATA] = {
+                .type = NLA_UNSPEC,     /* libnl doesn't grok BINARY yet */
+        },
+};
+
+
+/*
+ * Relays a message from user space to the driver
+ *
+ * The skb is passed to the driver-specific function with the netlink
+ * and generic netlink headers already stripped.
+ *
+ * This call will block while handling/relaying the message.
+ */
+static
+int wimax_gnl_doit_msg_from_user(struct sk_buff *skb, struct genl_info *info)
+{
+        int result, ifindex;
+        struct wimax_dev *wimax_dev;
+        struct device *dev;
+        struct nlmsghdr *nlh = info->nlhdr;
+        char *pipe_name;
+        void *msg_buf;
+        size_t msg_len;
+
+        might_sleep();
+        d_fnstart(3, NULL, "(skb %p info %p)\n", skb, info);
+        result = -ENODEV;
+        if (info->attrs[WIMAX_GNL_MSG_IFIDX] == NULL) {
+                printk(KERN_ERR "WIMAX_GNL_MSG_FROM_USER: can't find IFIDX "
+                       "attribute\n");
+                goto error_no_wimax_dev;
+        }
+        ifindex = nla_get_u32(info->attrs[WIMAX_GNL_MSG_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);
+
+        /* Unpack arguments */
+        result = -EINVAL;
+        if (info->attrs[WIMAX_GNL_MSG_DATA] == NULL) {
+                dev_err(dev, "WIMAX_GNL_MSG_FROM_USER: can't find MSG_DATA "
+                        "attribute\n");
+                goto error_no_data;
+        }
+        msg_buf = nla_data(info->attrs[WIMAX_GNL_MSG_DATA]);
+        msg_len = nla_len(info->attrs[WIMAX_GNL_MSG_DATA]);
+
+        if (info->attrs[WIMAX_GNL_MSG_PIPE_NAME] == NULL)
+                pipe_name = NULL;
+        else {
+                struct nlattr *attr = info->attrs[WIMAX_GNL_MSG_PIPE_NAME];
+                size_t attr_len = nla_len(attr);
+                /* libnl-1.1 does not yet support NLA_NUL_STRING */
+                result = -ENOMEM;
+                pipe_name = kstrndup(nla_data(attr), attr_len + 1, GFP_KERNEL);
+                if (pipe_name == NULL)
+                        goto error_alloc;
+                pipe_name[attr_len] = 0;
+        }
+        mutex_lock(&wimax_dev->mutex);
+        result = wimax_dev_is_ready(wimax_dev);
+        if (result < 0)
+                goto error_not_ready;
+        result = -ENOSYS;
+        if (wimax_dev->op_msg_from_user == NULL)
+                goto error_noop;
+
+        d_printf(1, dev,
+                 "CRX: nlmsghdr len %u type %u flags 0x%04x seq 0x%x pid %u\n",
+                 nlh->nlmsg_len, nlh->nlmsg_type, nlh->nlmsg_flags,
+                 nlh->nlmsg_seq, nlh->nlmsg_pid);
+        d_printf(1, dev, "CRX: wimax message %zu bytes\n", msg_len);
+        d_dump(2, dev, msg_buf, msg_len);
+
+        result = wimax_dev->op_msg_from_user(wimax_dev, pipe_name,
+                                             msg_buf, msg_len, info);
+error_noop:
+error_not_ready:
+        mutex_unlock(&wimax_dev->mutex);
+error_alloc:
+        kfree(pipe_name);
+error_no_data:
+        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;
+}
+
+
+/*
+ * Generic Netlink glue
+ */
+
+struct genl_ops wimax_gnl_msg_from_user = {
+        .cmd = WIMAX_GNL_OP_MSG_FROM_USER,
+        .flags = GENL_ADMIN_PERM,
+        .policy = wimax_gnl_msg_policy,
+        .doit = wimax_gnl_doit_msg_from_user,
+        .dumpit = NULL,
+};
+