1 files changed, 86 insertions, 0 deletions
diff --git a/arch/arm/mach-ep93xx/crunch.c b/arch/arm/mach-ep93xx/crunch.c
new file mode 100644
index 000000000..757032d82
--- /dev/null
+++ b/arch/arm/mach-ep93xx/crunch.c
@@ -0,0 +1,86 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * arch/arm/kernel/crunch.c
+ * Cirrus MaverickCrunch context switching and handling
+ *
+ * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
+ */
+
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/init.h>
+#include <linux/io.h>
+
+#include <asm/thread_notify.h>
+
+#include "soc.h"
+
+struct crunch_state *crunch_owner;
+
+void crunch_task_release(struct thread_info *thread)
+{
+	local_irq_disable();
+	if (crunch_owner == &thread->crunchstate)
+		crunch_owner = NULL;
+	local_irq_enable();
+}
+
+static int crunch_enabled(u32 devcfg)
+{
+	return !!(devcfg & EP93XX_SYSCON_DEVCFG_CPENA);
+}
+
+static int crunch_do(struct notifier_block *self, unsigned long cmd, void *t)
+{
+	struct thread_info *thread = (struct thread_info *)t;
+	struct crunch_state *crunch_state;
+	u32 devcfg;
+
+	crunch_state = &thread->crunchstate;
+
+	switch (cmd) {
+	case THREAD_NOTIFY_FLUSH:
+		memset(crunch_state, 0, sizeof(*crunch_state));
+
+		/*
+		 * FALLTHROUGH: Ensure we don't try to overwrite our newly
+		 * initialised state information on the first fault.
+		 */
+		fallthrough;
+
+	case THREAD_NOTIFY_EXIT:
+		crunch_task_release(thread);
+		break;
+
+	case THREAD_NOTIFY_SWITCH:
+		devcfg = __raw_readl(EP93XX_SYSCON_DEVCFG);
+		if (crunch_enabled(devcfg) || crunch_owner == crunch_state) {
+			/*
+			 * We don't use ep93xx_syscon_swlocked_write() here
+			 * because we are on the context switch path and
+			 * preemption is already disabled.
+			 */
+			devcfg ^= EP93XX_SYSCON_DEVCFG_CPENA;
+			__raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
+			__raw_writel(devcfg, EP93XX_SYSCON_DEVCFG);
+		}
+		break;
+	}
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block crunch_notifier_block = {
+	.notifier_call	= crunch_do,
+};
+
+int __init crunch_init(void)
+{
+	thread_register_notifier(&crunch_notifier_block);
+	elf_hwcap |= HWCAP_CRUNCH;
+
+	return 0;
+}