[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 328645d..d48f3ac 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