[PATCH] w1: Userspace communication protocol over connector.

There are three types of messages between w1 core and userspace:
1. Events. They are generated each time new master or slave device found
	either due to automatic or requested search.
2. Userspace commands. Includes read/write and search/alarm search comamnds.
3. Replies to userspace commands.

From: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 185 insertions, 30 deletions

diff --git a/drivers/w1/w1_netlink.c b/drivers/w1/w1_netlink.c
index 328645da7972..d48f3acdb8a2 100644
--- a/drivers/w1/w1_netlink.c
+++ b/drivers/w1/w1_netlink.c
@@ -21,6 +21,7 @@
 
 #include <linux/skbuff.h>
 #include <linux/netlink.h>
+#include <linux/connector.h>
 
 #include "w1.h"
 #include "w1_log.h"
@@ -29,50 +30,204 @@
 #ifndef NETLINK_DISABLED
 void w1_netlink_send(struct w1_master *dev, struct w1_netlink_msg *msg)
 {
-        unsigned int size;
-        struct sk_buff *skb;
-        struct w1_netlink_msg *data;
-        struct nlmsghdr *nlh;
+        char buf[sizeof(struct cn_msg) + sizeof(struct w1_netlink_msg)];
+        struct cn_msg *m = (struct cn_msg *)buf;
+        struct w1_netlink_msg *w = (struct w1_netlink_msg *)(m+1);
 
-        if (!dev->nls)
-                return;
+        memset(buf, 0, sizeof(buf));
 
-        size = NLMSG_SPACE(sizeof(struct w1_netlink_msg));
+        m->id.idx = CN_W1_IDX;
+        m->id.val = CN_W1_VAL;
 
-        skb = alloc_skb(size, GFP_ATOMIC);
-        if (!skb) {
-                dev_err(&dev->dev, "skb_alloc() failed.\n");
-                return;
-        }
+        m->seq = dev->seq++;
+        m->len = sizeof(struct w1_netlink_msg);
 
-        nlh = NLMSG_PUT(skb, 0, dev->seq++, NLMSG_DONE, size - sizeof(*nlh));
+        memcpy(w, msg, sizeof(struct w1_netlink_msg));
 
-        data = (struct w1_netlink_msg *)NLMSG_DATA(nlh);
+        cn_netlink_send(m, 0, GFP_KERNEL);
+}
 
-        memcpy(data, msg, sizeof(struct w1_netlink_msg));
+static int w1_process_command_master(struct w1_master *dev, struct cn_msg *msg,
+                struct w1_netlink_msg *hdr, struct w1_netlink_cmd *cmd)
+{
+        dev_dbg(&dev->dev, "%s: %s: cmd=%02x, len=%u.\n",
+                __func__, dev->name, cmd->cmd, cmd->len);
 
-        NETLINK_CB(skb).dst_group = dev->groups;
-        netlink_broadcast(dev->nls, skb, 0, dev->groups, GFP_ATOMIC);
+        if (cmd->cmd != W1_CMD_SEARCH && cmd->cmd != W1_CMD_ALARM_SEARCH)
+                return -EINVAL;
 
-nlmsg_failure:
-        return;
+        w1_search_process(dev, (cmd->cmd == W1_CMD_ALARM_SEARCH)?W1_ALARM_SEARCH:W1_SEARCH);
+        return 0;
 }
 
-int dev_init_netlink(struct w1_master *dev)
+static int w1_send_read_reply(struct w1_slave *sl, struct cn_msg *msg,
+                struct w1_netlink_msg *hdr, struct w1_netlink_cmd *cmd)
 {
-        dev->nls = netlink_kernel_create(NETLINK_W1, 1, NULL, THIS_MODULE);
-        if (!dev->nls) {
-                printk(KERN_ERR "Failed to create new netlink socket(%u) for w1 master %s.\n",
-                        NETLINK_W1, dev->dev.bus_id);
+        void *data;
+        struct w1_netlink_msg *h;
+        struct w1_netlink_cmd *c;
+        struct cn_msg *cm;
+        int err;
+
+        data = kzalloc(sizeof(struct cn_msg) +
+                        sizeof(struct w1_netlink_msg) +
+                        sizeof(struct w1_netlink_cmd) +
+                        cmd->len, GFP_KERNEL);
+        if (!data)
+                return -ENOMEM;
+
+        cm = (struct cn_msg *)(data);
+        h = (struct w1_netlink_msg *)(cm + 1);
+        c = (struct w1_netlink_cmd *)(h + 1);
+
+        memcpy(cm, msg, sizeof(struct cn_msg));
+        memcpy(h, hdr, sizeof(struct w1_netlink_msg));
+        memcpy(c, cmd, sizeof(struct w1_netlink_cmd));
+
+        cm->ack = msg->seq+1;
+        cm->len = sizeof(struct w1_netlink_msg) + sizeof(struct w1_netlink_cmd) + cmd->len;
+
+        h->len = sizeof(struct w1_netlink_cmd) + cmd->len;
+
+        memcpy(c->data, cmd->data, c->len);
+
+        err = cn_netlink_send(cm, 0, GFP_KERNEL);
+
+        kfree(data);
+
+        return err;
+}
+
+static int w1_process_command_slave(struct w1_slave *sl, struct cn_msg *msg,
+                struct w1_netlink_msg *hdr, struct w1_netlink_cmd *cmd)
+{
+        int err = 0;
+
+        dev_dbg(&sl->master->dev, "%s: %02x.%012llx.%02x: cmd=%02x, len=%u.\n",
+                __func__, sl->reg_num.family, (unsigned long long)sl->reg_num.id, sl->reg_num.crc,
+                cmd->cmd, cmd->len);
+
+        switch (cmd->cmd) {
+                case W1_CMD_READ:
+                        w1_read_block(sl->master, cmd->data, cmd->len);
+                        w1_send_read_reply(sl, msg, hdr, cmd);
+                        break;
+                case W1_CMD_WRITE:
+                        w1_write_block(sl->master, cmd->data, cmd->len);
+                        break;
+                case W1_CMD_SEARCH:
+                case W1_CMD_ALARM_SEARCH:
+                        w1_search_process(sl->master,
+                                        (cmd->cmd == W1_CMD_ALARM_SEARCH)?W1_ALARM_SEARCH:W1_SEARCH);
+                        break;
+                default:
+                        err = -1;
+                        break;
         }
 
-        return 0;
+        return err;
+}
+
+static void w1_cn_callback(void *data)
+{
+        struct cn_msg *msg = data;
+        struct w1_netlink_msg *m = (struct w1_netlink_msg *)(msg + 1);
+        struct w1_netlink_cmd *cmd;
+        struct w1_slave *sl;
+        struct w1_master *dev;
+        int err = 0;
+
+        while (msg->len && !err) {
+                struct w1_reg_num id;
+                u16 mlen = m->len;
+                u8 *cmd_data = m->data;
+
+                dev = NULL;
+                sl = NULL;
+
+                memcpy(&id, m->id.id, sizeof(id));
+#if 0
+                printk("%s: %02x.%012llx.%02x: type=%02x, len=%u.\n",
+                                __func__, id.family, (unsigned long long)id.id, id.crc, m->type, m->len);
+#endif
+                if (m->len + sizeof(struct w1_netlink_msg) > msg->len) {
+                        err = -E2BIG;
+                        break;
+                }
+
+                if (!mlen)
+                        goto out_cont;
+
+                if (m->type == W1_MASTER_CMD) {
+                        dev = w1_search_master_id(m->id.mst.id);
+                } else if (m->type == W1_SLAVE_CMD) {
+                        sl = w1_search_slave(&id);
+                        if (sl)
+                                dev = sl->master;
+                }
+
+                if (!dev) {
+                        err = -ENODEV;
+                        goto out_cont;
+                }
+
+                down(&dev->mutex);
+
+                if (sl && w1_reset_select_slave(sl)) {
+                        err = -ENODEV;
+                        goto out_up;
+                }
+
+                while (mlen) {
+                        cmd = (struct w1_netlink_cmd *)cmd_data;
+
+                        if (cmd->len + sizeof(struct w1_netlink_cmd) > mlen) {
+                                err = -E2BIG;
+                                break;
+                        }
+
+                        if (sl)
+                                w1_process_command_slave(sl, msg, m, cmd);
+                        else
+                                w1_process_command_master(dev, msg, m, cmd);
+
+                        cmd_data += cmd->len + sizeof(struct w1_netlink_cmd);
+                        mlen -= cmd->len + sizeof(struct w1_netlink_cmd);
+                }
+out_up:
+                atomic_dec(&dev->refcnt);
+                if (sl)
+                        atomic_dec(&sl->refcnt);
+                up(&dev->mutex);
+out_cont:
+                msg->len -= sizeof(struct w1_netlink_msg) + m->len;
+                m = (struct w1_netlink_msg *)(((u8 *)m) + sizeof(struct w1_netlink_msg) + m->len);
+
+                /*
+                 * Let's allow requests for nonexisting devices.
+                 */
+                if (err == -ENODEV)
+                        err = 0;
+        }
+#if 0
+        if (err) {
+                printk("%s: malformed message. Dropping.\n", __func__);
+        }
+#endif
 }
 
-void dev_fini_netlink(struct w1_master *dev)
+int w1_init_netlink(void)
 {
-        if (dev->nls && dev->nls->sk_socket)
-                sock_release(dev->nls->sk_socket);
+        struct cb_id w1_id = {.idx = CN_W1_IDX, .val = CN_W1_VAL};
+
+        return cn_add_callback(&w1_id, "w1", &w1_cn_callback);
+}
+
+void w1_fini_netlink(void)
+{
+        struct cb_id w1_id = {.idx = CN_W1_IDX, .val = CN_W1_VAL};
+
+        cn_del_callback(&w1_id);
 }
 #else
 #warning Netlink support is disabled. Please compile with NET support enabled.
@@ -81,12 +236,12 @@ void w1_netlink_send(struct w1_master *dev, struct w1_netlink_msg *msg)
 {
 }
 
-int dev_init_netlink(struct w1_master *dev)
+int w1_init_netlink(void)
 {
         return 0;
 }
 
-void dev_fini_netlink(struct w1_master *dev)
+void w1_fini_netlink(void)
 {
 }
 #endif