w1: add touch block command

Writes and returns sampled data back to userspace.
Signed-off-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/w1/w1.h

@@ -210,6 +210,7 @@ u8 w1_read_8(struct w1_master *);
 int w1_reset_bus(struct w1_master *);
 u8 w1_calc_crc8(u8 *, int);
 void w1_write_block(struct w1_master *, const u8 *, int);
+void w1_touch_block(struct w1_master *, u8 *, int);
 u8 w1_read_block(struct w1_master *, u8 *, int);
 int w1_reset_select_slave(struct w1_slave *sl);
 void w1_next_pullup(struct w1_master *, int);

drivers/w1/w1_io.c

@@ -238,7 +238,6 @@ EXPORT_SYMBOL_GPL(w1_read_8);
  * @param dev     the master device
  * @param buf     pointer to the data to write
  * @param len     the number of bytes to write
- * @return        the byte read
  */
 void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
 {
@@ -255,6 +254,31 @@ void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
 }
 EXPORT_SYMBOL_GPL(w1_write_block);
 
+/**
+ * Touches a series of bytes.
+ *
+ * @param dev     the master device
+ * @param buf     pointer to the data to write
+ * @param len     the number of bytes to write
+ */
+void w1_touch_block(struct w1_master *dev, u8 *buf, int len)
+{
+	int i, j;
+	u8 tmp;
+
+	for (i = 0; i < len; ++i) {
+		tmp = 0;
+		for (j = 0; j < 8; ++j) {
+			if (j == 7)
+				w1_pre_write(dev);
+			tmp |= w1_touch_bit(dev, (buf[i] >> j) & 0x1) << j;
+		}
+
+		buf[i] = tmp;
+	}
+}
+EXPORT_SYMBOL_GPL(w1_touch_block);
+
 /**
  * Reads a series of bytes.
  *

drivers/w1/w1_netlink.c

@@ -108,6 +108,10 @@ static int w1_process_command_slave(struct w1_slave *sl, struct cn_msg *msg,
 		cmd->cmd, cmd->len);
 
 	switch (cmd->cmd) {
+		case W1_CMD_TOUCH:
+			w1_touch_block(sl->master, cmd->data, cmd->len);
+			w1_send_read_reply(sl, msg, hdr, cmd);
+			break;
 		case W1_CMD_READ:
 			w1_read_block(sl->master, cmd->data, cmd->len);
 			w1_send_read_reply(sl, msg, hdr, cmd);
@@ -208,9 +212,6 @@ static void w1_cn_callback(void *data)
 			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) {
@@ -227,6 +228,10 @@ static void w1_cn_callback(void *data)
 			goto out_cont;
 		}
 
+		err = 0;
+		if (!mlen)
+			goto out_cont;
+
 		mutex_lock(&dev->mutex);
 
 		if (sl && w1_reset_select_slave(sl)) {

drivers/w1/w1_netlink.h

@@ -56,6 +56,7 @@ struct w1_netlink_msg
 #define W1_CMD_WRITE		0x1
 #define W1_CMD_SEARCH		0x2
 #define W1_CMD_ALARM_SEARCH	0x3
+#define W1_CMD_TOUCH		0x4
 
 struct w1_netlink_cmd
 {