Subject: [PATCH 14/16] drivers/fsi: Add master unscan

From: [email-masked] (Chris Bostic)
Date: Tue, 6 Dec 2016 18:14:35 -0600

From: Chris Bostic <[email-masked]>

Allow a master to undo a previous scan.  Should a master scan a bus
twice it will need to ensure it doesn't double register any
previously detected device.

Signed-off-by: Chris Bostic <[email-masked]>
---
 drivers/fsi/fsi-core.c   | 36 +++++++++++++++++++++++++++++++++++-
 drivers/fsi/fsi-master.h |  2 ++
 include/linux/fsi.h      |  1 +
 3 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/drivers/fsi/fsi-core.c b/drivers/fsi/fsi-core.c
index a28434b..8ccfe50 100644
--- a/drivers/fsi/fsi-core.c
+++ b/drivers/fsi/fsi-core.c
@@ -41,6 +41,8 @@
 static atomic_t master_idx = ATOMIC_INIT(-1);
 
 struct fsi_slave {
+	struct list_head	list_link;	/* Master's list of slaves */
+	struct list_head	my_engines;
 	struct device		dev;
 	struct fsi_master	*master;
 	int			link;
@@ -196,6 +198,8 @@ static int fsi_slave_scan(struct fsi_slave *slave)
 	uint32_t conf;
 	int rc, i;
 
+	INIT_LIST_HEAD(&slave->my_engines);
+
 	/*
 	 * scan engines
 	 *
@@ -264,7 +268,9 @@ static int fsi_slave_scan(struct fsi_slave *slave)
 			if (rc) {
 				dev_warn(&slave->dev, "add failed: %d\n", rc);
 				put_device(&dev->dev);
+				continue;
 			}
+			list_add(&dev->link, &slave->my_engines);
 		}
 
 		engine_addr += slots * engine_page_size;
@@ -357,7 +363,7 @@ static int fsi_slave_init(struct fsi_master *master,
 		put_device(&slave->dev);
 		return rc;
 	}
-
+	list_add(&slave->list_link, &master->my_slaves);
 	fsi_slave_scan(slave);
 	return 0;
 }
@@ -388,6 +394,11 @@ static int fsi_master_scan(struct fsi_master *master)
 	int link, slave_id, rc;
 	uint32_t smode;
 
+	if (!master->slave_list) {
+		INIT_LIST_HEAD(&master->my_slaves);
+		master->slave_list = true;
+	}
+
 	for (link = 0; link < master->n_links; link++) {
 		rc = fsi_master_link_enable(master, link);
 		if (rc) {
@@ -423,9 +434,31 @@ static int fsi_master_scan(struct fsi_master *master)
 	return 0;
 }
 
+static void fsi_master_unscan(struct fsi_master *master)
+{
+	struct fsi_slave *slave, *slave_tmp;
+	struct fsi_device *fsi_dev, *fsi_dev_tmp;
+
+	if (!master->slave_list)
+		return;
+
+	list_for_each_entry_safe(slave, slave_tmp, &master->my_slaves,
+							list_link) {
+		list_del(&slave->list_link);
+		list_for_each_entry_safe(fsi_dev, fsi_dev_tmp,
+					&slave->my_engines, link) {
+			list_del(&fsi_dev->link);
+			put_device(&fsi_dev->dev);
+		}
+		device_unregister(&slave->dev);
+	}
+	master->slave_list = false;
+}
+
 int fsi_master_register(struct fsi_master *master)
 {
 	master->idx = atomic_inc_return(&master_idx);
+	master->slave_list = false;
 	get_device(master->dev);
 	fsi_master_scan(master);
 	return 0;
@@ -434,6 +467,7 @@ int fsi_master_register(struct fsi_master *master)
 
 void fsi_master_unregister(struct fsi_master *master)
 {
+	fsi_master_unscan(master);
 	put_device(master->dev);
 }
 EXPORT_SYMBOL_GPL(fsi_master_unregister);
diff --git a/drivers/fsi/fsi-master.h b/drivers/fsi/fsi-master.h
index 56aad0e..454af2b 100644
--- a/drivers/fsi/fsi-master.h
+++ b/drivers/fsi/fsi-master.h
@@ -20,6 +20,8 @@
 #include <linux/device.h>
 
 struct fsi_master {
+	struct list_head my_slaves;
+	bool		slave_list;
 	struct device	*dev;
 	int		idx;
 	int		n_links;
diff --git a/include/linux/fsi.h b/include/linux/fsi.h
index 66bce48..924502b 100644
--- a/include/linux/fsi.h
+++ b/include/linux/fsi.h
@@ -18,6 +18,7 @@
 #include <linux/device.h>
 
 struct fsi_device {
+	struct list_head	link;	/* for slave's list */
 	struct device		dev;
 	u8			engine_type;
 	u8			version;
-- 
1.8.2.2