1 files changed, 290 insertions, 0 deletions
diff --git a/arch/powerpc/platforms/powernv/opal-async.c b/arch/powerpc/platforms/powernv/opal-async.c
new file mode 100644
index 000000000..c094fdf58
--- /dev/null
+++ b/arch/powerpc/platforms/powernv/opal-async.c
@@ -0,0 +1,290 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PowerNV OPAL asynchronous completion interfaces
+ *
+ * Copyright 2013-2017 IBM Corp.
+ */
+
+#undef DEBUG
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/semaphore.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/gfp.h>
+#include <linux/of.h>
+#include <asm/machdep.h>
+#include <asm/opal.h>
+
+enum opal_async_token_state {
+	ASYNC_TOKEN_UNALLOCATED = 0,
+	ASYNC_TOKEN_ALLOCATED,
+	ASYNC_TOKEN_DISPATCHED,
+	ASYNC_TOKEN_ABANDONED,
+	ASYNC_TOKEN_COMPLETED
+};
+
+struct opal_async_token {
+	enum opal_async_token_state state;
+	struct opal_msg response;
+};
+
+static DECLARE_WAIT_QUEUE_HEAD(opal_async_wait);
+static DEFINE_SPINLOCK(opal_async_comp_lock);
+static struct semaphore opal_async_sem;
+static unsigned int opal_max_async_tokens;
+static struct opal_async_token *opal_async_tokens;
+
+static int __opal_async_get_token(void)
+{
+	unsigned long flags;
+	int i, token = -EBUSY;
+
+	spin_lock_irqsave(&opal_async_comp_lock, flags);
+
+	for (i = 0; i < opal_max_async_tokens; i++) {
+		if (opal_async_tokens[i].state == ASYNC_TOKEN_UNALLOCATED) {
+			opal_async_tokens[i].state = ASYNC_TOKEN_ALLOCATED;
+			token = i;
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
+	return token;
+}
+
+/*
+ * Note: If the returned token is used in an opal call and opal returns
+ * OPAL_ASYNC_COMPLETION you MUST call one of opal_async_wait_response() or
+ * opal_async_wait_response_interruptible() at least once before calling another
+ * opal_async_* function
+ */
+int opal_async_get_token_interruptible(void)
+{
+	int token;
+
+	/* Wait until a token is available */
+	if (down_interruptible(&opal_async_sem))
+		return -ERESTARTSYS;
+
+	token = __opal_async_get_token();
+	if (token < 0)
+		up(&opal_async_sem);
+
+	return token;
+}
+EXPORT_SYMBOL_GPL(opal_async_get_token_interruptible);
+
+static int __opal_async_release_token(int token)
+{
+	unsigned long flags;
+	int rc;
+
+	if (token < 0 || token >= opal_max_async_tokens) {
+		pr_err("%s: Passed token is out of range, token %d\n",
+				__func__, token);
+		return -EINVAL;
+	}
+
+	spin_lock_irqsave(&opal_async_comp_lock, flags);
+	switch (opal_async_tokens[token].state) {
+	case ASYNC_TOKEN_COMPLETED:
+	case ASYNC_TOKEN_ALLOCATED:
+		opal_async_tokens[token].state = ASYNC_TOKEN_UNALLOCATED;
+		rc = 0;
+		break;
+	/*
+	 * DISPATCHED and ABANDONED tokens must wait for OPAL to respond.
+	 * Mark a DISPATCHED token as ABANDONED so that the response handling
+	 * code knows no one cares and that it can free it then.
+	 */
+	case ASYNC_TOKEN_DISPATCHED:
+		opal_async_tokens[token].state = ASYNC_TOKEN_ABANDONED;
+		fallthrough;
+	default:
+		rc = 1;
+	}
+	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
+
+	return rc;
+}
+
+int opal_async_release_token(int token)
+{
+	int ret;
+
+	ret = __opal_async_release_token(token);
+	if (!ret)
+		up(&opal_async_sem);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(opal_async_release_token);
+
+int opal_async_wait_response(uint64_t token, struct opal_msg *msg)
+{
+	if (token >= opal_max_async_tokens) {
+		pr_err("%s: Invalid token passed\n", __func__);
+		return -EINVAL;
+	}
+
+	if (!msg) {
+		pr_err("%s: Invalid message pointer passed\n", __func__);
+		return -EINVAL;
+	}
+
+	/*
+	 * There is no need to mark the token as dispatched, wait_event()
+	 * will block until the token completes.
+	 *
+	 * Wakeup the poller before we wait for events to speed things
+	 * up on platforms or simulators where the interrupts aren't
+	 * functional.
+	 */
+	opal_wake_poller();
+	wait_event(opal_async_wait, opal_async_tokens[token].state
+			== ASYNC_TOKEN_COMPLETED);
+	memcpy(msg, &opal_async_tokens[token].response, sizeof(*msg));
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(opal_async_wait_response);
+
+int opal_async_wait_response_interruptible(uint64_t token, struct opal_msg *msg)
+{
+	unsigned long flags;
+	int ret;
+
+	if (token >= opal_max_async_tokens) {
+		pr_err("%s: Invalid token passed\n", __func__);
+		return -EINVAL;
+	}
+
+	if (!msg) {
+		pr_err("%s: Invalid message pointer passed\n", __func__);
+		return -EINVAL;
+	}
+
+	/*
+	 * The first time this gets called we mark the token as DISPATCHED
+	 * so that if wait_event_interruptible() returns not zero and the
+	 * caller frees the token, we know not to actually free the token
+	 * until the response comes.
+	 *
+	 * Only change if the token is ALLOCATED - it may have been
+	 * completed even before the caller gets around to calling this
+	 * the first time.
+	 *
+	 * There is also a dirty great comment at the token allocation
+	 * function that if the opal call returns OPAL_ASYNC_COMPLETION to
+	 * the caller then the caller *must* call this or the not
+	 * interruptible version before doing anything else with the
+	 * token.
+	 */
+	if (opal_async_tokens[token].state == ASYNC_TOKEN_ALLOCATED) {
+		spin_lock_irqsave(&opal_async_comp_lock, flags);
+		if (opal_async_tokens[token].state == ASYNC_TOKEN_ALLOCATED)
+			opal_async_tokens[token].state = ASYNC_TOKEN_DISPATCHED;
+		spin_unlock_irqrestore(&opal_async_comp_lock, flags);
+	}
+
+	/*
+	 * Wakeup the poller before we wait for events to speed things
+	 * up on platforms or simulators where the interrupts aren't
+	 * functional.
+	 */
+	opal_wake_poller();
+	ret = wait_event_interruptible(opal_async_wait,
+			opal_async_tokens[token].state ==
+			ASYNC_TOKEN_COMPLETED);
+	if (!ret)
+		memcpy(msg, &opal_async_tokens[token].response, sizeof(*msg));
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(opal_async_wait_response_interruptible);
+
+/* Called from interrupt context */
+static int opal_async_comp_event(struct notifier_block *nb,
+		unsigned long msg_type, void *msg)
+{
+	struct opal_msg *comp_msg = msg;
+	enum opal_async_token_state state;
+	unsigned long flags;
+	uint64_t token;
+
+	if (msg_type != OPAL_MSG_ASYNC_COMP)
+		return 0;
+
+	token = be64_to_cpu(comp_msg->params[0]);
+	spin_lock_irqsave(&opal_async_comp_lock, flags);
+	state = opal_async_tokens[token].state;
+	opal_async_tokens[token].state = ASYNC_TOKEN_COMPLETED;
+	spin_unlock_irqrestore(&opal_async_comp_lock, flags);
+
+	if (state == ASYNC_TOKEN_ABANDONED) {
+		/* Free the token, no one else will */
+		opal_async_release_token(token);
+		return 0;
+	}
+	memcpy(&opal_async_tokens[token].response, comp_msg, sizeof(*comp_msg));
+	wake_up(&opal_async_wait);
+
+	return 0;
+}
+
+static struct notifier_block opal_async_comp_nb = {
+		.notifier_call	= opal_async_comp_event,
+		.next		= NULL,
+		.priority	= 0,
+};
+
+int __init opal_async_comp_init(void)
+{
+	struct device_node *opal_node;
+	const __be32 *async;
+	int err;
+
+	opal_node = of_find_node_by_path("/ibm,opal");
+	if (!opal_node) {
+		pr_err("%s: Opal node not found\n", __func__);
+		err = -ENOENT;
+		goto out;
+	}
+
+	async = of_get_property(opal_node, "opal-msg-async-num", NULL);
+	if (!async) {
+		pr_err("%s: %pOF has no opal-msg-async-num\n",
+				__func__, opal_node);
+		err = -ENOENT;
+		goto out_opal_node;
+	}
+
+	opal_max_async_tokens = be32_to_cpup(async);
+	opal_async_tokens = kcalloc(opal_max_async_tokens,
+			sizeof(*opal_async_tokens), GFP_KERNEL);
+	if (!opal_async_tokens) {
+		err = -ENOMEM;
+		goto out_opal_node;
+	}
+
+	err = opal_message_notifier_register(OPAL_MSG_ASYNC_COMP,
+			&opal_async_comp_nb);
+	if (err) {
+		pr_err("%s: Can't register OPAL event notifier (%d)\n",
+				__func__, err);
+		kfree(opal_async_tokens);
+		goto out_opal_node;
+	}
+
+	sema_init(&opal_async_sem, opal_max_async_tokens);
+
+out_opal_node:
+	of_node_put(opal_node);
+out:
+	return err;
+}