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authorRafael J. Wysocki <rjw@sisk.pl>2011-08-25 15:34:01 +0200
committerRafael J. Wysocki <rjw@sisk.pl>2011-08-25 15:34:01 +0200
commitef27bed1870dbd5fd363ff5ec51eebd5a695e277 (patch)
treeef563bb07f259386fbe2477ec9a01e7ead011bcc /drivers/base/power/common.c
parent5c095a0e0d600d5a5a4207eaadabd18db46395ce (diff)
PM: Reference counting of power.subsys_data
Since the power.subsys_data device field will be used by multiple filesystems, introduce a reference counting mechanism for it to avoid freeing it prematurely or changing its value at a wrong time. Make the PM clocks management code that currently is the only user of power.subsys_data use the new reference counting. Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Diffstat (limited to 'drivers/base/power/common.c')
-rw-r--r--drivers/base/power/common.c87
1 files changed, 87 insertions, 0 deletions
diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
new file mode 100644
index 00000000000..d398cf029b3
--- /dev/null
+++ b/drivers/base/power/common.c
@@ -0,0 +1,87 @@
+/*
+ * drivers/base/power/common.c - Common device power management code.
+ *
+ * Copyright (C) 2011 Rafael J. Wysocki <rjw@sisk.pl>, Renesas Electronics Corp.
+ *
+ * This file is released under the GPLv2.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/pm_runtime.h>
+
+/**
+ * dev_pm_get_subsys_data - Create or refcount power.subsys_data for device.
+ * @dev: Device to handle.
+ *
+ * If power.subsys_data is NULL, point it to a new object, otherwise increment
+ * its reference counter. Return 1 if a new object has been created, otherwise
+ * return 0 or error code.
+ */
+int dev_pm_get_subsys_data(struct device *dev)
+{
+ struct pm_subsys_data *psd;
+ int ret = 0;
+
+ psd = kzalloc(sizeof(*psd), GFP_KERNEL);
+ if (!psd)
+ return -ENOMEM;
+
+ spin_lock_irq(&dev->power.lock);
+
+ if (dev->power.subsys_data) {
+ dev->power.subsys_data->refcount++;
+ } else {
+ spin_lock_init(&psd->lock);
+ psd->refcount = 1;
+ dev->power.subsys_data = psd;
+ pm_clk_init(dev);
+ psd = NULL;
+ ret = 1;
+ }
+
+ spin_unlock_irq(&dev->power.lock);
+
+ /* kfree() verifies that its argument is nonzero. */
+ kfree(psd);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_get_subsys_data);
+
+/**
+ * dev_pm_put_subsys_data - Drop reference to power.subsys_data.
+ * @dev: Device to handle.
+ *
+ * If the reference counter of power.subsys_data is zero after dropping the
+ * reference, power.subsys_data is removed. Return 1 if that happens or 0
+ * otherwise.
+ */
+int dev_pm_put_subsys_data(struct device *dev)
+{
+ struct pm_subsys_data *psd;
+ int ret = 0;
+
+ spin_lock_irq(&dev->power.lock);
+
+ psd = dev_to_psd(dev);
+ if (!psd) {
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (--psd->refcount == 0) {
+ dev->power.subsys_data = NULL;
+ kfree(psd);
+ ret = 1;
+ }
+
+ out:
+ spin_unlock_irq(&dev->power.lock);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(dev_pm_put_subsys_data);