[PATCH v4 09/12] i2c: designware-baytrail: Acquire P-Unit access on bus acquire

[Hans de Goede <hdegoede@redhat.com>]

Acquire P-Unit access to stop others from accessing the P-Unit while the
PMIC i2c bus is in use. This is necessary because accessing the P-Unit
from the kernel may result in the P-Unit trying to access the PMIC i2c
bus, which results in a hang when it happens while we own the PMIC i2c
bus semaphore.

BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=155241
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: tagorereddy <tagore.chandan@gmail.com>
Acked-by: Wolfram Sang <wsa@the-dreams.de>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
Changes in v2:
-Spelling: P-Unit, PMIC
-Adjust for iosf_mbi_punit_lock/_unlock to _acquire/_release rename
---
 drivers/i2c/busses/i2c-designware-baytrail.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-baytrail.c b/drivers/i2c/busses/i2c-designware-baytrail.c
index 3effc9a..7eddc3b 100644
--- a/drivers/i2c/busses/i2c-designware-baytrail.c
+++ b/drivers/i2c/busses/i2c-designware-baytrail.c
@@ -62,6 +62,8 @@ static void reset_semaphore(struct dw_i2c_dev *dev)
 		dev_err(dev->dev, "iosf failed to reset punit semaphore during write\n");
 
 	pm_qos_update_request(&dev->pm_qos, PM_QOS_DEFAULT_VALUE);
+
+	iosf_mbi_punit_release();
 }
 
 static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
@@ -79,6 +81,8 @@ static int baytrail_i2c_acquire(struct dw_i2c_dev *dev)
 	if (!dev->release_lock)
 		return 0;
 
+	iosf_mbi_punit_acquire();
+
 	/*
 	 * Disallow the CPU to enter C6 or C7 state, entering these states
 	 * requires the punit to talk to the pmic and if this happens while
-- 
2.9.3