C6X: process management

Original port to early 2.6 kernel using TI COFF toolchain.
Brought up to date by Mark Salter <msalter@redhat.com>

Signed-off-by: Aurelien Jacquiot <a-jacquiot@ti.com>
Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

2 files changed, 337 insertions, 0 deletions

diff --git a/arch/c6x/kernel/process.c b/arch/c6x/kernel/process.c
new file mode 100644
index 000000000000..aa65c879323b
--- /dev/null
+++ b/arch/c6x/kernel/process.c
@@ -0,0 +1,263 @@
+/*
+ *  Port on Texas Instruments TMS320C6x architecture
+ *
+ *  Copyright (C) 2004, 2006, 2009, 2010, 2011 Texas Instruments Incorporated
+ *  Author: Aurelien Jacquiot (aurelien.jacquiot@jaluna.com)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ *
+ */
+#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 <asm/syscalls.h>
+
+/* hooks for board specific support */
+void    (*c6x_restart)(void);
+void    (*c6x_halt)(void);
+
+extern asmlinkage void ret_from_fork(void);
+
+static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
+static struct sighand_struct init_sighand = INIT_SIGHAND(init_sighand);
+
+/*
+ * Initial thread structure.
+ */
+union thread_union init_thread_union __init_task_data = {
+        INIT_THREAD_INFO(init_task)
+};
+
+/*
+ * Initial task structure.
+ */
+struct task_struct init_task = INIT_TASK(init_task);
+EXPORT_SYMBOL(init_task);
+
+/*
+ * power off function, if any
+ */
+void (*pm_power_off)(void);
+EXPORT_SYMBOL(pm_power_off);
+
+static void c6x_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));
+}
+
+/*
+ * The idle loop for C64x
+ */
+void cpu_idle(void)
+{
+        /* endless idle loop with no priority at all */
+        while (1) {
+                tick_nohz_stop_sched_tick(1);
+                while (1) {
+                        local_irq_disable();
+                        if (need_resched()) {
+                                local_irq_enable();
+                                break;
+                        }
+                        c6x_idle(); /* enables local irqs */
+                }
+                tick_nohz_restart_sched_tick();
+
+                preempt_enable_no_resched();
+                schedule();
+                preempt_disable();
+        }
+}
+
+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();
+}
+
+static void kernel_thread_helper(int dummy, void *arg, int (*fn)(void *))
+{
+        do_exit(fn(arg));
+}
+
+/*
+ * Create a kernel thread
+ */
+int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags)
+{
+        struct pt_regs regs;
+
+        /*
+         * copy_thread sets a4 to zero (child return from fork)
+         * so we can't just set things up to directly return to
+         * fn.
+         */
+        memset(&regs, 0, sizeof(regs));
+        regs.b4 = (unsigned long) arg;
+        regs.a6 = (unsigned long) fn;
+        regs.pc = (unsigned long) kernel_thread_helper;
+        local_save_flags(regs.csr);
+        regs.csr |= 1;
+        regs.tsr = 5; /* Set GEE and GIE in TSR */
+
+        /* Ok, create the new process.. */
+        return do_fork(flags | CLONE_VM | CLONE_UNTRACED, -1, &regs,
+                       0, NULL, NULL);
+}
+EXPORT_SYMBOL(kernel_thread);
+
+void flush_thread(void)
+{
+}
+
+void exit_thread(void)
+{
+}
+
+SYSCALL_DEFINE1(c6x_clone, struct pt_regs *, regs)
+{
+        unsigned long clone_flags;
+        unsigned long newsp;
+
+        /* syscall puts clone_flags in A4 and usp in B4 */
+        clone_flags = regs->orig_a4;
+        if (regs->b4)
+                newsp = regs->b4;
+        else
+                newsp = regs->sp;
+
+        return do_fork(clone_flags, newsp, regs, 0, (int __user *)regs->a6,
+                       (int __user *)regs->b6);
+}
+
+/*
+ * 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;
+
+        set_fs(USER_DS);
+        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, struct pt_regs *regs)
+{
+        struct pt_regs *childregs;
+
+        childregs = task_pt_regs(p);
+
+        *childregs = *regs;
+        childregs->a4 = 0;
+
+        if (usp == -1)
+                /* case of  __kernel_thread: we return to supervisor space */
+                childregs->sp = (unsigned long)(childregs + 1);
+        else
+                /* Otherwise use the given stack */
+                childregs->sp = usp;
+
+        /* Set usp/ksp */
+        p->thread.usp = childregs->sp;
+        /* switch_to uses stack to save/restore 14 callee-saved regs */
+        thread_saved_ksp(p) = (unsigned long)childregs - 8;
+        p->thread.pc = (unsigned int) ret_from_fork;
+        p->thread.wchan = (unsigned long) ret_from_fork;
+#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;
+}
+
+/*
+ * c6x_execve() executes a new program.
+ */
+SYSCALL_DEFINE4(c6x_execve, const char __user *, name,
+                const char __user *const __user *, argv,
+                const char __user *const __user *, envp,
+                struct pt_regs *, regs)
+{
+        int error;
+        char *filename;
+
+        filename = getname(name);
+        error = PTR_ERR(filename);
+        if (IS_ERR(filename))
+                goto out;
+
+        error = do_execve(filename, argv, envp, regs);
+        putname(filename);
+out:
+        return error;
+}
+
+unsigned long get_wchan(struct task_struct *p)
+{
+        return p->thread.wchan;
+}
diff --git a/arch/c6x/kernel/switch_to.S b/arch/c6x/kernel/switch_to.S
new file mode 100644
index 000000000000..09177ed0fa5c
--- /dev/null
+++ b/arch/c6x/kernel/switch_to.S
@@ -0,0 +1,74 @@
+/*
+ *  Copyright (C) 2011 Texas Instruments Incorporated
+ *  Author: Mark Salter (msalter@redhat.com)
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License version 2 as
+ *  published by the Free Software Foundation.
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm-offsets.h>
+
+#define SP      B15
+
+        /*
+         * void __switch_to(struct thread_info *prev,
+         *                  struct thread_info *next,
+         *                  struct task_struct *tsk) ;
+         */
+ENTRY(__switch_to)
+        LDDW    .D2T2   *+B4(THREAD_B15_14),B7:B6
+ ||     MV      .L2X    A4,B5   ; prev
+ ||     MV      .L1X    B4,A5   ; next
+ ||     MVC     .S2     RILC,B1
+
+        STW     .D2T2   B3,*+B5(THREAD_PC)
+ ||     STDW    .D1T1   A13:A12,*+A4(THREAD_A13_12)
+ ||     MVC     .S2     ILC,B0
+
+        LDW     .D2T2   *+B4(THREAD_PC),B3
+ ||     LDDW    .D1T1   *+A5(THREAD_A13_12),A13:A12
+
+        STDW    .D1T1   A11:A10,*+A4(THREAD_A11_10)
+ ||     STDW    .D2T2   B1:B0,*+B5(THREAD_RICL_ICL)
+#ifndef __DSBT__
+ ||     MVKL    .S2     current_ksp,B1
+#endif
+
+        STDW    .D2T2   B15:B14,*+B5(THREAD_B15_14)
+ ||     STDW    .D1T1   A15:A14,*+A4(THREAD_A15_14)
+#ifndef __DSBT__
+ ||     MVKH    .S2     current_ksp,B1
+#endif
+
+        ;; Switch to next SP
+        MV      .S2     B7,SP
+#ifdef __DSBT__
+ ||     STW     .D2T2   B7,*+B14(current_ksp)
+#else
+ ||     STW     .D2T2   B7,*B1
+ ||     MV      .L2     B6,B14
+#endif
+ ||     LDDW    .D1T1   *+A5(THREAD_RICL_ICL),A1:A0
+
+        STDW    .D2T2   B11:B10,*+B5(THREAD_B11_10)
+ ||     LDDW    .D1T1   *+A5(THREAD_A15_14),A15:A14
+
+        STDW    .D2T2   B13:B12,*+B5(THREAD_B13_12)
+ ||     LDDW    .D1T1   *+A5(THREAD_A11_10),A11:A10
+
+        B       .S2     B3              ; return in next E1
+ ||     LDDW    .D2T2   *+B4(THREAD_B13_12),B13:B12
+
+        LDDW    .D2T2   *+B4(THREAD_B11_10),B11:B10
+        NOP
+
+        MV      .L2X    A0,B0
+ ||     MV      .S1     A6,A4
+
+        MVC     .S2     B0,ILC
+ ||     MV      .L2X    A1,B1
+
+        MVC     .S2     B1,RILC
+ENDPROC(__switch_to)