[PATCH v8 4/6] remoteproc: pru: Make sysfs entries read-only for PRU client driven boots

[MD Danish Anwar]

From: Suman Anna <s-anna@xxxxxx>

The PRU remoteproc driver is not configured for 'auto-boot' by default,
and allows to be booted either by in-kernel PRU client drivers or by
userspace using the generic remoteproc sysfs interfaces. The sysfs
interfaces should not be permitted to change the remoteproc firmwares
or states when a PRU is being managed by an in-kernel client driver.
Use the newly introduced remoteproc generic 'sysfs_read_only' flag to
provide these restrictions by setting and clearing it appropriately
during the PRU acquire and release steps.

Co-developed-by: Suman Anna <s-anna@xxxxxx>
Co-developed-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>
Co-developed-by: Puranjay Mohan <p-mohan@xxxxxx>
Signed-off-by: MD Danish Anwar <danishanwar@xxxxxx>
---
 drivers/remoteproc/pru_rproc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/remoteproc/pru_rproc.c b/drivers/remoteproc/pru_rproc.c
index 7d4ed39b3772..bca7550d79d2 100644
--- a/drivers/remoteproc/pru_rproc.c
+++ b/drivers/remoteproc/pru_rproc.c
@@ -228,6 +228,7 @@ struct rproc *pru_rproc_get(struct device_node *np, int index,
 	}
 
 	pru->client_np = np;
+	rproc->sysfs_read_only = true;
 
 	mutex_unlock(&pru->lock);
 
@@ -266,6 +267,7 @@ void pru_rproc_put(struct rproc *rproc)
 	}
 
 	pru->client_np = NULL;
+	rproc->sysfs_read_only = false;
 	mutex_unlock(&pru->lock);
 
 	rproc_put(rproc);
-- 
2.25.1