X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=drivers%2Fw1%2Fw1_io.c;h=8e8b64cfafb69a417bded8e6f3f745ca3a7e44a1;hb=56aa53391059e3730a304da4dd96b7b123b9fb75;hp=3ebe9726a9e55471ae9383fe262fc61de2727200;hpb=ae6e59caefd8d4097ccb096c95df95ec7e52fe88;p=mirror_ubuntu-eoan-kernel.git

diff --git a/drivers/w1/w1_io.c b/drivers/w1/w1_io.c
index 3ebe9726a9e5..8e8b64cfafb6 100644
--- a/drivers/w1/w1_io.c
+++ b/drivers/w1/w1_io.c
@@ -389,6 +389,32 @@ int w1_reset_select_slave(struct w1_slave *sl)
 }
 EXPORT_SYMBOL_GPL(w1_reset_select_slave);
 
+/**
+ * When the workflow with a slave amongst many requires several
+ * successive commands a reset between each, this function is similar
+ * to doing a reset then a match ROM for the last matched ROM. The
+ * advantage being that the matched ROM step is skipped in favor of the
+ * resume command. The slave must support the command of course.
+ *
+ * If the bus has only one slave, traditionnaly the match ROM is skipped
+ * and a "SKIP ROM" is done for efficiency. On multi-slave busses, this
+ * doesn't work of course, but the resume command is the next best thing.
+ *
+ * The w1 master lock must be held.
+ *
+ * @param dev     the master device
+ */
+int w1_reset_resume_command(struct w1_master *dev)
+{
+	if (w1_reset_bus(dev))
+		return -1;
+
+	/* This will make only the last matched slave perform a skip ROM. */
+	w1_write_8(dev, W1_RESUME_CMD);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(w1_reset_resume_command);
+
 /**
  * Put out a strong pull-up of the specified duration after the next write
  * operation.  Not all hardware supports strong pullups.  Hardware that