1 files changed, 151 insertions, 0 deletions
diff --git a/arch/c6x/kernel/process.c b/arch/c6x/kernel/process.c
new file mode 100644
index 000000000..9f4fd6a40
--- /dev/null
+++ b/arch/c6x/kernel/process.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  Port on Texas Instruments TMS320C6x architecture
+ *
+ *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
+ *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+ */
+#include <linux/module.h>
+#include <linux/unistd.h>
+#include <linux/ptrace.h>
+#include <linux/init_task.h>
+#include <linux/tick.h>
+#include <linux/mqueue.h>
+#include <linux/syscalls.h>
+#include <linux/reboot.h>
+#include <linux/sched/task.h>
+#include <linux/sched/task_stack.h>
+
+#include <asm/syscalls.h>
+
+/* hooks for board specific support */
+void	(*c6x_restart)(void);
+void	(*c6x_halt)(void);
+
+extern asmlinkage void ret_from_fork(void);
+extern asmlinkage void ret_from_kernel_thread(void);
+
+/*
+ * power off function, if any
+ */
+void (*pm_power_off)(void);
+EXPORT_SYMBOL(pm_power_off);
+
+void arch_cpu_idle(void)
+{
+	unsigned long tmp;
+
+	/*
+	 * Put local_irq_enable and idle in same execute packet
+	 * to make them atomic and avoid race to idle with
+	 * interrupts enabled.
+	 */
+	asm volatile ("   mvc .s2 CSR,%0\n"
+		      "   or  .d2 1,%0,%0\n"
+		      "   mvc .s2 %0,CSR\n"
+		      "|| idle\n"
+		      : "=b"(tmp));
+}
+
+static void halt_loop(void)
+{
+	printk(KERN_EMERG "System Halted, OK to turn off power\n");
+	local_irq_disable();
+	while (1)
+		asm volatile("idle\n");
+}
+
+void machine_restart(char *__unused)
+{
+	if (c6x_restart)
+		c6x_restart();
+	halt_loop();
+}
+
+void machine_halt(void)
+{
+	if (c6x_halt)
+		c6x_halt();
+	halt_loop();
+}
+
+void machine_power_off(void)
+{
+	if (pm_power_off)
+		pm_power_off();
+	halt_loop();
+}
+
+void flush_thread(void)
+{
+}
+
+/*
+ * Do necessary setup to start up a newly executed thread.
+ */
+void start_thread(struct pt_regs *regs, unsigned int pc, unsigned long usp)
+{
+	/*
+	 * The binfmt loader will setup a "full" stack, but the C6X
+	 * operates an "empty" stack. So we adjust the usp so that
+	 * argc doesn't get destroyed if an interrupt is taken before
+	 * it is read from the stack.
+	 *
+	 * NB: Library startup code needs to match this.
+	 */
+	usp -= 8;
+
+	regs->pc  = pc;
+	regs->sp  = usp;
+	regs->tsr |= 0x40; /* set user mode */
+	current->thread.usp = usp;
+}
+
+/*
+ * Copy a new thread context in its stack.
+ */
+int copy_thread(unsigned long clone_flags, unsigned long usp,
+		unsigned long ustk_size, struct task_struct *p,
+		unsigned long tls)
+{
+	struct pt_regs *childregs;
+
+	childregs = task_pt_regs(p);
+
+	if (unlikely(p->flags & PF_KTHREAD)) {
+		/* case of  __kernel_thread: we return to supervisor space */
+		memset(childregs, 0, sizeof(struct pt_regs));
+		childregs->sp = (unsigned long)(childregs + 1);
+		p->thread.pc = (unsigned long) ret_from_kernel_thread;
+		childregs->a0 = usp;		/* function */
+		childregs->a1 = ustk_size;	/* argument */
+	} else {
+		/* Otherwise use the given stack */
+		*childregs = *current_pt_regs();
+		if (usp)
+			childregs->sp = usp;
+		p->thread.pc = (unsigned long) ret_from_fork;
+	}
+
+	/* Set usp/ksp */
+	p->thread.usp = childregs->sp;
+	thread_saved_ksp(p) = (unsigned long)childregs - 8;
+	p->thread.wchan	= p->thread.pc;
+#ifdef __DSBT__
+	{
+		unsigned long dp;
+
+		asm volatile ("mv .S2 b14,%0\n" : "=b"(dp));
+
+		thread_saved_dp(p) = dp;
+		if (usp == -1)
+			childregs->dp = dp;
+	}
+#endif
+	return 0;
+}
+
+unsigned long get_wchan(struct task_struct *p)
+{
+	return p->thread.wchan;
+}