linux-kernel - [PATCH 4/4] parport: daisy: use new parport device model

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Date:   Wed, 16 Oct 2019 15:45:40 +0100
From:   Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, Michal Kubecek <mkubecek@...e.cz>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH 4/4] parport: daisy: use new parport device model

Modify parport daisy driver to use the new parallel port device model.

Last attempt was '1aec4211204d ("parport: daisy: use new parport device
model")' which failed as daisy was also trying to load the low level
driver and that resulted in a deadlock.

Cc: Michal Kubecek <mkubecek@...e.cz>
Cc: Steven Rostedt (VMware) <rostedt@...dmis.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@...il.com>
---

Steven, Michal,
Can you please test this series in your test environment and verify that
I am not breaking anything this time.

 drivers/parport/daisy.c | 40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/parport/daisy.c b/drivers/parport/daisy.c
index 5484a46dafda..95b5c3363582 100644
--- a/drivers/parport/daisy.c
+++ b/drivers/parport/daisy.c
@@ -45,6 +45,7 @@ static struct daisydev {
 static DEFINE_SPINLOCK(topology_lock);
 
 static int numdevs;
+static bool daisy_init_done;
 
 /* Forward-declaration of lower-level functions. */
 static int mux_present(struct parport *port);
@@ -87,6 +88,24 @@ static struct parport *clone_parport(struct parport *real, int muxport)
 	return extra;
 }
 
+static int daisy_drv_probe(struct pardevice *par_dev)
+{
+	struct device_driver *drv = par_dev->dev.driver;
+
+	if (strcmp(drv->name, "daisy_drv"))
+		return -ENODEV;
+	if (strcmp(par_dev->name, daisy_dev_name))
+		return -ENODEV;
+
+	return 0;
+}
+
+static struct parport_driver daisy_driver = {
+	.name = "daisy_drv",
+	.probe = daisy_drv_probe,
+	.devmodel = true,
+};
+
 /* Discover the IEEE1284.3 topology on a port -- muxes and daisy chains.
  * Return value is number of devices actually detected. */
 int parport_daisy_init(struct parport *port)
@@ -98,6 +117,23 @@ int parport_daisy_init(struct parport *port)
 	int i;
 	int last_try = 0;
 
+	if (!daisy_init_done) {
+		/*
+		 * flag should be marked true first as
+		 * parport_register_driver() might try to load the low
+		 * level driver which will lead to announcing new ports
+		 * and which will again come back here at
+		 * parport_daisy_init()
+		 */
+		daisy_init_done = true;
+		i = parport_register_driver(&daisy_driver);
+		if (i) {
+			pr_err("daisy registration failed\n");
+			daisy_init_done = false;
+			return i;
+		}
+	}
+
 again:
 	/* Because this is called before any other devices exist,
 	 * we don't have to claim exclusive access.  */
@@ -213,10 +249,12 @@ void parport_daisy_fini(struct parport *port)
 struct pardevice *parport_open(int devnum, const char *name)
 {
 	struct daisydev *p = topology;
+	struct pardev_cb par_cb;
 	struct parport *port;
 	struct pardevice *dev;
 	int daisy;
 
+	memset(&par_cb, 0, sizeof(par_cb));
 	spin_lock(&topology_lock);
 	while (p && p->devnum != devnum)
 		p = p->next;
@@ -230,7 +268,7 @@ struct pardevice *parport_open(int devnum, const char *name)
 	port = parport_get_port(p->port);
 	spin_unlock(&topology_lock);
 
-	dev = parport_register_device(port, name, NULL, NULL, NULL, 0, NULL);
+	dev = parport_register_dev_model(port, name, &par_cb, devnum);
 	parport_put_port(port);
 	if (!dev)
 		return NULL;
-- 
2.11.0