dm: Add Hardware Spinlock class

This is uclass for Hardware Spinlocks.
It implements two mandatory operations: lock and unlock
and one optional relax operation.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Patrice Chotard <patrice.chotard@st.com>

1 files changed, 140 insertions, 0 deletions

diff --git a/include/hwspinlock.h b/include/hwspinlock.h
new file mode 100644
index 0000000..99389c1
--- /dev/null
+++ b/include/hwspinlock.h
@@ -0,0 +1,140 @@
+/* SPDX-License-Identifier: GPL-2.0+ OR BSD-3-Clause */
+/*
+ * Copyright (C) 2018, STMicroelectronics - All Rights Reserved
+ */
+
+#ifndef _HWSPINLOCK_H_
+#define _HWSPINLOCK_H_
+
+/**
+ * Implement a hwspinlock uclass.
+ * Hardware spinlocks are used to perform hardware protection of
+ * critical sections and synchronisation between multiprocessors.
+ */
+
+struct udevice;
+
+/**
+ * struct hwspinlock - A handle to (allowing control of) a single hardware
+ * spinlock.
+ *
+ * @dev: The device which implements the hardware spinlock.
+ * @id: The hardware spinlock ID within the provider.
+ */
+struct hwspinlock {
+	struct udevice *dev;
+	unsigned long id;
+};
+
+#if CONFIG_IS_ENABLED(DM_HWSPINLOCK)
+
+/**
+ * hwspinlock_get_by_index - Get a hardware spinlock by integer index
+ *
+ * This looks up and request a hardware spinlock. The index is relative to the
+ * client device; each device is assumed to have n hardware spinlock associated
+ * with it somehow, and this function finds and requests one of them.
+ *
+ * @dev:	The client device.
+ * @index:	The index of the hardware spinlock to request, within the
+ *		client's list of hardware spinlock.
+ * @hws:	A pointer to a hardware spinlock struct to initialize.
+ * @return 0 if OK, or a negative error code.
+ */
+int hwspinlock_get_by_index(struct udevice *dev,
+			    int index, struct hwspinlock *hws);
+
+/**
+ * Lock the hardware spinlock
+ *
+ * @hws:	A hardware spinlock struct that previously requested by
+ *		hwspinlock_get_by_index
+ * @timeout:	Timeout value in msecs
+ * @return: 0 if OK, -ETIMEDOUT if timeout, -ve on other errors
+ */
+int hwspinlock_lock_timeout(struct hwspinlock *hws, unsigned int timeout);
+
+/**
+ * Unlock the hardware spinlock
+ *
+ * @hws:	A hardware spinlock struct that previously requested by
+ *		hwspinlock_get_by_index
+ * @return: 0 if OK, -ve on error
+ */
+int hwspinlock_unlock(struct hwspinlock *hws);
+
+#else
+
+static inline int hwspinlock_get_by_index(struct udevice *dev,
+					  int index,
+					  struct hwspinlock *hws)
+{
+	return -ENOSYS;
+}
+
+static inline int hwspinlock_lock_timeout(struct hwspinlock *hws,
+					  int timeout)
+{
+	return -ENOSYS;
+}
+
+static inline int hwspinlock_unlock(struct hwspinlock *hws)
+{
+	return -ENOSYS;
+}
+
+#endif /* CONFIG_DM_HWSPINLOCK */
+
+struct ofnode_phandle_args;
+
+/**
+ * struct hwspinlock_ops - Driver model hwspinlock operations
+ *
+ * The uclass interface is implemented by all hwspinlock devices which use
+ * driver model.
+ */
+struct hwspinlock_ops {
+	/**
+	 * of_xlate - Translate a client's device-tree (OF) hardware specifier.
+	 *
+	 * The hardware core calls this function as the first step in
+	 * implementing a client's hwspinlock_get_by_*() call.
+	 *
+	 * @hws:	The hardware spinlock struct to hold the translation
+	 *			result.
+	 * @args:	The hardware spinlock specifier values from device tree.
+	 * @return 0 if OK, or a negative error code.
+	 */
+	int (*of_xlate)(struct hwspinlock *hws,
+			struct ofnode_phandle_args *args);
+
+	/**
+	 * Lock the hardware spinlock
+	 *
+	 * @dev:	hwspinlock Device
+	 * @index:	index of the lock to be used
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*lock)(struct udevice *dev, int index);
+
+	/**
+	 * Unlock the hardware spinlock
+	 *
+	 * @dev:	hwspinlock Device
+	 * @index:	index of the lock to be unlocked
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*unlock)(struct udevice *dev, int index);
+
+	/**
+	 * Relax - optional
+	 *       Platform-specific relax method, called by hwspinlock core
+	 *       while spinning on a lock, between two successive call to
+	 *       lock
+	 *
+	 * @dev:	hwspinlock Device
+	 */
+	void (*relax)(struct udevice *dev);
+};
+
+#endif /* _HWSPINLOCK_H_ */