x86/platform/intel/iosf_mbi: Add a mutex for P-Unit access
One some systems the P-Unit accesses the PMIC to change various voltages
through the same bus as other kernel drivers use for e.g. battery
monitoring.
If a driver sends requests to the P-Unit which require the P-Unit to access
the PMIC bus while another driver is also accessing the PMIC bus various
bad things happen.
This commit adds a mutex to protect the P-Unit against simultaneous
accesses and 2 functions to lock / unlock this mutex.
Note on these systems the i2c-bus driver will request a sempahore from the
P-Unit for exclusive access to the PMIC bus when i2c drivers are accessing
it, but this does not appear to be sufficient, we still need to avoid
making certain P-Unit requests during the access window to avoid problems.
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>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20170210102802.20898-2-hdegoede@redhat.com
diff --git a/arch/x86/platform/intel/iosf_mbi.c b/arch/x86/platform/intel/iosf_mbi.c
index edf2c54..ed24fa9f 100644
--- a/arch/x86/platform/intel/iosf_mbi.c
+++ b/arch/x86/platform/intel/iosf_mbi.c
@@ -34,6 +34,7 @@
static struct pci_dev *mbi_pdev;
static DEFINE_SPINLOCK(iosf_mbi_lock);
+static DEFINE_MUTEX(iosf_mbi_punit_mutex);
static inline u32 iosf_mbi_form_mcr(u8 op, u8 port, u8 offset)
{
@@ -190,6 +191,18 @@ bool iosf_mbi_available(void)
}
EXPORT_SYMBOL(iosf_mbi_available);
+void iosf_mbi_punit_acquire(void)
+{
+ mutex_lock(&iosf_mbi_punit_mutex);
+}
+EXPORT_SYMBOL(iosf_mbi_punit_acquire);
+
+void iosf_mbi_punit_release(void)
+{
+ mutex_unlock(&iosf_mbi_punit_mutex);
+}
+EXPORT_SYMBOL(iosf_mbi_punit_release);
+
#ifdef CONFIG_IOSF_MBI_DEBUG
static u32 dbg_mdr;
static u32 dbg_mcr;