/*
   *  linux/arch/arm/vfp/vfpmodule.c
   *
   *  Copyright (C) 2004 ARM Limited.
   *  Written by Deep Blue Solutions Limited.
   *
   * 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/types.h>

  #include <linux/cpu.h>

  #include <linux/cpu_pm.h>

  #include <linux/kernel.h>

  #include <linux/notifier.h>

  #include <linux/signal.h>
  #include <linux/sched.h>

  #include <linux/smp.h>

  #include <linux/init.h>

  #include <asm/cputype.h>

  #include <asm/thread_notify.h>

  #include <asm/vfp.h>
  
  #include "vfpinstr.h"
  #include "vfp.h"
  
  /*
   * Our undef handlers (in entry.S)
   */
  void vfp_testing_entry(void);
  void vfp_support_entry(void);

  void vfp_null_entry(void);

  void (*vfp_vector)(void) = vfp_null_entry;

  
  /*

   * Dual-use variable.
   * Used in startup: set to non-zero if VFP checks fail
   * After startup, holds VFP architecture
   */
  unsigned int VFP_arch;
  
  /*

   * The pointer to the vfpstate structure of the thread which currently
   * owns the context held in the VFP hardware, or NULL if the hardware
   * context is invalid.

   *
   * For UP, this is sufficient to tell which thread owns the VFP context.
   * However, for SMP, we also need to check the CPU number stored in the
   * saved state too to catch migrations.

   */
  union vfp_state *vfp_current_hw_state[NR_CPUS];

  
  /*

   * Is 'thread's most up to date state stored in this CPUs hardware?
   * Must be called from non-preemptible context.

   */

  static bool vfp_state_in_hw(unsigned int cpu, struct thread_info *thread)
  {
  #ifdef CONFIG_SMP
  	if (thread->vfpstate.hard.cpu != cpu)
  		return false;
  #endif
  	return vfp_current_hw_state[cpu] == &thread->vfpstate;
  }
  
  /*
   * Force a reload of the VFP context from the thread structure.  We do
   * this by ensuring that access to the VFP hardware is disabled, and

   * clear vfp_current_hw_state.  Must be called from non-preemptible context.

   */
  static void vfp_force_reload(unsigned int cpu, struct thread_info *thread)
  {
  	if (vfp_state_in_hw(cpu, thread)) {
  		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
  		vfp_current_hw_state[cpu] = NULL;
  	}
  #ifdef CONFIG_SMP
  	thread->vfpstate.hard.cpu = NR_CPUS;
  #endif
  }

  /*
   * Per-thread VFP initialization.
   */
  static void vfp_thread_flush(struct thread_info *thread)
  {
  	union vfp_state *vfp = &thread->vfpstate;
  	unsigned int cpu;

  	/*
  	 * Disable VFP to ensure we initialize it first.  We must ensure

  	 * that the modification of vfp_current_hw_state[] and hardware
  	 * disable are done for the same CPU and without preemption.
  	 *
  	 * Do this first to ensure that preemption won't overwrite our
  	 * state saving should access to the VFP be enabled at this point.

  	 */
  	cpu = get_cpu();

  	if (vfp_current_hw_state[cpu] == vfp)
  		vfp_current_hw_state[cpu] = NULL;

  	fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
  	put_cpu();

  
  	memset(vfp, 0, sizeof(union vfp_state));
  
  	vfp->hard.fpexc = FPEXC_EN;
  	vfp->hard.fpscr = FPSCR_ROUND_NEAREST;
  #ifdef CONFIG_SMP
  	vfp->hard.cpu = NR_CPUS;
  #endif

  }

  static void vfp_thread_exit(struct thread_info *thread)

  {
  	/* release case: Per-thread VFP cleanup. */
  	union vfp_state *vfp = &thread->vfpstate;

  	unsigned int cpu = get_cpu();

  	if (vfp_current_hw_state[cpu] == vfp)
  		vfp_current_hw_state[cpu] = NULL;

  	put_cpu();

  }

  static void vfp_thread_copy(struct thread_info *thread)
  {
  	struct thread_info *parent = current_thread_info();
  
  	vfp_sync_hwstate(parent);
  	thread->vfpstate = parent->vfpstate;

  #ifdef CONFIG_SMP
  	thread->vfpstate.hard.cpu = NR_CPUS;
  #endif

  }

  /*
   * When this function is called with the following 'cmd's, the following
   * is true while this function is being run:
   *  THREAD_NOFTIFY_SWTICH:
   *   - the previously running thread will not be scheduled onto another CPU.
   *   - the next thread to be run (v) will not be running on another CPU.
   *   - thread->cpu is the local CPU number
   *   - not preemptible as we're called in the middle of a thread switch
   *  THREAD_NOTIFY_FLUSH:
   *   - the thread (v) will be running on the local CPU, so
   *	v === current_thread_info()
   *   - thread->cpu is the local CPU number at the time it is accessed,
   *	but may change at any time.
   *   - we could be preempted if tree preempt rcu is enabled, so
   *	it is unsafe to use thread->cpu.

   *  THREAD_NOTIFY_EXIT
   *   - the thread (v) will be running on the local CPU, so
   *	v === current_thread_info()
   *   - thread->cpu is the local CPU number at the time it is accessed,
   *	but may change at any time.
   *   - we could be preempted if tree preempt rcu is enabled, so
   *	it is unsafe to use thread->cpu.

   */

  static int vfp_notifier(struct notifier_block *self, unsigned long cmd, void *v)

  {

  	struct thread_info *thread = v;

  	u32 fpexc;
  #ifdef CONFIG_SMP
  	unsigned int cpu;
  #endif

  	switch (cmd) {
  	case THREAD_NOTIFY_SWITCH:
  		fpexc = fmrx(FPEXC);

  
  #ifdef CONFIG_SMP

  		cpu = thread->cpu;

  		/*
  		 * On SMP, if VFP is enabled, save the old state in
  		 * case the thread migrates to a different CPU. The
  		 * restoring is done lazily.
  		 */

  		if ((fpexc & FPEXC_EN) && vfp_current_hw_state[cpu])

  			vfp_save_state(vfp_current_hw_state[cpu], fpexc);

  #endif

  		/*
  		 * Always disable VFP so we can lazily save/restore the
  		 * old state.
  		 */

  		fmxr(FPEXC, fpexc & ~FPEXC_EN);

  		break;

  	case THREAD_NOTIFY_FLUSH:

  		vfp_thread_flush(thread);

  		break;
  
  	case THREAD_NOTIFY_EXIT:

  		vfp_thread_exit(thread);

  		break;
  
  	case THREAD_NOTIFY_COPY:
  		vfp_thread_copy(thread);

  		break;
  	}

  	return NOTIFY_DONE;

  }

  static struct notifier_block vfp_notifier_block = {
  	.notifier_call	= vfp_notifier,
  };

  /*
   * Raise a SIGFPE for the current process.
   * sicode describes the signal being raised.
   */

  static void vfp_raise_sigfpe(unsigned int sicode, struct pt_regs *regs)

  {
  	siginfo_t info;
  
  	memset(&info, 0, sizeof(info));
  
  	info.si_signo = SIGFPE;
  	info.si_code = sicode;

  	info.si_addr = (void __user *)(instruction_pointer(regs) - 4);

  
  	/*
  	 * This is the same as NWFPE, because it's not clear what
  	 * this is used for
  	 */
  	current->thread.error_code = 0;
  	current->thread.trap_no = 6;

  	send_sig_info(SIGFPE, &info, current);

  }

  static void vfp_panic(char *reason, u32 inst)

  {
  	int i;
  
  	printk(KERN_ERR "VFP: Error: %s
  ", reason);
  	printk(KERN_ERR "VFP: EXC 0x%08x SCR 0x%08x INST 0x%08x
  ",

  		fmrx(FPEXC), fmrx(FPSCR), inst);

  	for (i = 0; i < 32; i += 2)
  		printk(KERN_ERR "VFP: s%2u: 0x%08x s%2u: 0x%08x
  ",
  		       i, vfp_get_float(i), i+1, vfp_get_float(i+1));
  }
  
  /*
   * Process bitmask of exception conditions.
   */
  static void vfp_raise_exceptions(u32 exceptions, u32 inst, u32 fpscr, struct pt_regs *regs)
  {
  	int si_code = 0;
  
  	pr_debug("VFP: raising exceptions %08x
  ", exceptions);

  	if (exceptions == VFP_EXCEPTION_ERROR) {

  		vfp_panic("unhandled bounce", inst);

  		vfp_raise_sigfpe(0, regs);
  		return;
  	}
  
  	/*

  	 * If any of the status flags are set, update the FPSCR.

  	 * Comparison instructions always return at least one of
  	 * these flags set.
  	 */

  	if (exceptions & (FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V))
  		fpscr &= ~(FPSCR_N|FPSCR_Z|FPSCR_C|FPSCR_V);

  	fpscr |= exceptions;
  
  	fmxr(FPSCR, fpscr);
  
  #define RAISE(stat,en,sig)				\
  	if (exceptions & stat && fpscr & en)		\
  		si_code = sig;
  
  	/*
  	 * These are arranged in priority order, least to highest.
  	 */

  	RAISE(FPSCR_DZC, FPSCR_DZE, FPE_FLTDIV);

  	RAISE(FPSCR_IXC, FPSCR_IXE, FPE_FLTRES);
  	RAISE(FPSCR_UFC, FPSCR_UFE, FPE_FLTUND);
  	RAISE(FPSCR_OFC, FPSCR_OFE, FPE_FLTOVF);
  	RAISE(FPSCR_IOC, FPSCR_IOE, FPE_FLTINV);
  
  	if (si_code)
  		vfp_raise_sigfpe(si_code, regs);
  }
  
  /*
   * Emulate a VFP instruction.
   */
  static u32 vfp_emulate_instruction(u32 inst, u32 fpscr, struct pt_regs *regs)
  {

  	u32 exceptions = VFP_EXCEPTION_ERROR;

  
  	pr_debug("VFP: emulate: INST=0x%08x SCR=0x%08x
  ", inst, fpscr);
  
  	if (INST_CPRTDO(inst)) {
  		if (!INST_CPRT(inst)) {
  			/*
  			 * CPDO
  			 */
  			if (vfp_single(inst)) {
  				exceptions = vfp_single_cpdo(inst, fpscr);
  			} else {
  				exceptions = vfp_double_cpdo(inst, fpscr);
  			}
  		} else {
  			/*
  			 * A CPRT instruction can not appear in FPINST2, nor
  			 * can it cause an exception.  Therefore, we do not
  			 * have to emulate it.
  			 */
  		}
  	} else {
  		/*
  		 * A CPDT instruction can not appear in FPINST2, nor can
  		 * it cause an exception.  Therefore, we do not have to
  		 * emulate it.
  		 */
  	}

  	return exceptions & ~VFP_NAN_FLAG;

  }
  
  /*
   * Package up a bounce condition.
   */

  void VFP_bounce(u32 trigger, u32 fpexc, struct pt_regs *regs)

  {

  	u32 fpscr, orig_fpscr, fpsid, exceptions;

  
  	pr_debug("VFP: bounce: trigger %08x fpexc %08x
  ", trigger, fpexc);
  
  	/*

  	 * At this point, FPEXC can have the following configuration:
  	 *
  	 *  EX DEX IXE
  	 *  0   1   x   - synchronous exception
  	 *  1   x   0   - asynchronous exception
  	 *  1   x   1   - sychronous on VFP subarch 1 and asynchronous on later
  	 *  0   0   1   - synchronous on VFP9 (non-standard subarch 1
  	 *                implementation), undefined otherwise
  	 *
  	 * Clear various bits and enable access to the VFP so we can
  	 * handle the bounce.

  	 */

  	fmxr(FPEXC, fpexc & ~(FPEXC_EX|FPEXC_DEX|FPEXC_FP2V|FPEXC_VV|FPEXC_TRAP_MASK));

  	fpsid = fmrx(FPSID);

  	orig_fpscr = fpscr = fmrx(FPSCR);
  
  	/*

  	 * Check for the special VFP subarch 1 and FPSCR.IXE bit case

  	 */

  	if ((fpsid & FPSID_ARCH_MASK) == (1 << FPSID_ARCH_BIT)
  	    && (fpscr & FPSCR_IXE)) {
  		/*
  		 * Synchronous exception, emulate the trigger instruction
  		 */

  		goto emulate;
  	}

  	if (fpexc & FPEXC_EX) {

  #ifndef CONFIG_CPU_FEROCEON

  		/*
  		 * Asynchronous exception. The instruction is read from FPINST
  		 * and the interrupted instruction has to be restarted.
  		 */
  		trigger = fmrx(FPINST);
  		regs->ARM_pc -= 4;

  #endif

  	} else if (!(fpexc & FPEXC_DEX)) {
  		/*
  		 * Illegal combination of bits. It can be caused by an
  		 * unallocated VFP instruction but with FPSCR.IXE set and not
  		 * on VFP subarch 1.
  		 */
  		 vfp_raise_exceptions(VFP_EXCEPTION_ERROR, trigger, fpscr, regs);

  		goto exit;

  	}

  
  	/*

  	 * Modify fpscr to indicate the number of iterations remaining.
  	 * If FPEXC.EX is 0, FPEXC.DEX is 1 and the FPEXC.VV bit indicates
  	 * whether FPEXC.VECITR or FPSCR.LEN is used.

  	 */

  	if (fpexc & (FPEXC_EX | FPEXC_VV)) {

  		u32 len;
  
  		len = fpexc + (1 << FPEXC_LENGTH_BIT);
  
  		fpscr &= ~FPSCR_LENGTH_MASK;
  		fpscr |= (len & FPEXC_LENGTH_MASK) << (FPSCR_LENGTH_BIT - FPEXC_LENGTH_BIT);
  	}
  
  	/*
  	 * Handle the first FP instruction.  We used to take note of the
  	 * FPEXC bounce reason, but this appears to be unreliable.
  	 * Emulate the bounced instruction instead.
  	 */

  	exceptions = vfp_emulate_instruction(trigger, fpscr, regs);

  	if (exceptions)

  		vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);

  
  	/*

  	 * If there isn't a second FP instruction, exit now. Note that
  	 * the FPEXC.FP2V bit is valid only if FPEXC.EX is 1.

  	 */

  	if (fpexc ^ (FPEXC_EX | FPEXC_FP2V))

  		goto exit;

  
  	/*
  	 * The barrier() here prevents fpinst2 being read
  	 * before the condition above.
  	 */
  	barrier();
  	trigger = fmrx(FPINST2);

  
   emulate:

  	exceptions = vfp_emulate_instruction(trigger, orig_fpscr, regs);

  	if (exceptions)
  		vfp_raise_exceptions(exceptions, trigger, orig_fpscr, regs);

   exit:
  	preempt_enable();

  }

  static void vfp_enable(void *unused)
  {
  	u32 access = get_copro_access();
  
  	/*
  	 * Enable full access to VFP (cp10 and cp11)
  	 */
  	set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11));
  }

  #ifdef CONFIG_CPU_PM

  static int vfp_pm_suspend(void)

  {
  	struct thread_info *ti = current_thread_info();
  	u32 fpexc = fmrx(FPEXC);
  
  	/* if vfp is on, then save state for resumption */
  	if (fpexc & FPEXC_EN) {
  		printk(KERN_DEBUG "%s: saving vfp state
  ", __func__);
  		vfp_save_state(&ti->vfpstate, fpexc);
  
  		/* disable, just in case */
  		fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);
  	}
  
  	/* clear any information we had about last context state */

  	memset(vfp_current_hw_state, 0, sizeof(vfp_current_hw_state));

  
  	return 0;
  }

  static void vfp_pm_resume(void)

  {
  	/* ensure we have access to the vfp */
  	vfp_enable(NULL);
  
  	/* and disable it to ensure the next usage restores the state */
  	fmxr(FPEXC, fmrx(FPEXC) & ~FPEXC_EN);

  }

  static int vfp_cpu_pm_notifier(struct notifier_block *self, unsigned long cmd,
  	void *v)
  {
  	switch (cmd) {
  	case CPU_PM_ENTER:
  		vfp_pm_suspend();
  		break;
  	case CPU_PM_ENTER_FAILED:
  	case CPU_PM_EXIT:
  		vfp_pm_resume();
  		break;
  	}
  	return NOTIFY_OK;
  }
  
  static struct notifier_block vfp_cpu_pm_notifier_block = {
  	.notifier_call = vfp_cpu_pm_notifier,

  };

  static void vfp_pm_init(void)
  {

  	cpu_pm_register_notifier(&vfp_cpu_pm_notifier_block);

  }

  #else
  static inline void vfp_pm_init(void) { }

  #endif /* CONFIG_CPU_PM */

  /*
   * Ensure that the VFP state stored in 'thread->vfpstate' is up to date
   * with the hardware state.
   */

  void vfp_sync_hwstate(struct thread_info *thread)

  {
  	unsigned int cpu = get_cpu();

  	if (vfp_state_in_hw(cpu, thread)) {

  		u32 fpexc = fmrx(FPEXC);

  		/*
  		 * Save the last VFP state on this CPU.
  		 */
  		fmxr(FPEXC, fpexc | FPEXC_EN);
  		vfp_save_state(&thread->vfpstate, fpexc | FPEXC_EN);

  		fmxr(FPEXC, fpexc);
  	}

  	put_cpu();
  }

  /* Ensure that the thread reloads the hardware VFP state on the next use. */

  void vfp_flush_hwstate(struct thread_info *thread)
  {
  	unsigned int cpu = get_cpu();

  	vfp_force_reload(cpu, thread);

  	put_cpu();
  }

  /*
   * VFP hardware can lose all context when a CPU goes offline.

   * As we will be running in SMP mode with CPU hotplug, we will save the
   * hardware state at every thread switch.  We clear our held state when
   * a CPU has been killed, indicating that the VFP hardware doesn't contain
   * a threads VFP state.  When a CPU starts up, we re-enable access to the
   * VFP hardware.

   *
   * Both CPU_DYING and CPU_STARTING are called on the CPU which
   * is being offlined/onlined.
   */
  static int vfp_hotplug(struct notifier_block *b, unsigned long action,
  	void *hcpu)
  {
  	if (action == CPU_DYING || action == CPU_DYING_FROZEN) {

  		vfp_force_reload((long)hcpu, current_thread_info());

  	} else if (action == CPU_STARTING || action == CPU_STARTING_FROZEN)
  		vfp_enable(NULL);
  	return NOTIFY_OK;
  }

  /*
   * VFP support code initialisation.
   */
  static int __init vfp_init(void)
  {
  	unsigned int vfpsid;

  	unsigned int cpu_arch = cpu_architecture();

  	if (cpu_arch >= CPU_ARCH_ARMv6)
  		vfp_enable(NULL);

  
  	/*
  	 * First check that there is a VFP that we can use.
  	 * The handler is already setup to just log calls, so
  	 * we just need to read the VFPSID register.
  	 */

  	vfp_vector = vfp_testing_entry;

  	barrier();

  	vfpsid = fmrx(FPSID);

  	barrier();

  	vfp_vector = vfp_null_entry;

  
  	printk(KERN_INFO "VFP support v0.3: ");

  	if (VFP_arch)

  		printk("not present
  ");

  	else if (vfpsid & FPSID_NODOUBLE) {

  		printk("no double precision support
  ");
  	} else {

  		hotcpu_notifier(vfp_hotplug, 0);

  		smp_call_function(vfp_enable, NULL, 1);

  		VFP_arch = (vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT;  /* Extract the architecture version */
  		printk("implementor %02x architecture %d part %02x variant %x rev %x
  ",
  			(vfpsid & FPSID_IMPLEMENTER_MASK) >> FPSID_IMPLEMENTER_BIT,
  			(vfpsid & FPSID_ARCH_MASK) >> FPSID_ARCH_BIT,
  			(vfpsid & FPSID_PART_MASK) >> FPSID_PART_BIT,
  			(vfpsid & FPSID_VARIANT_MASK) >> FPSID_VARIANT_BIT,
  			(vfpsid & FPSID_REV_MASK) >> FPSID_REV_BIT);

  		vfp_vector = vfp_support_entry;

  
  		thread_register_notifier(&vfp_notifier_block);

  		vfp_pm_init();

  
  		/*
  		 * We detected VFP, and the support code is
  		 * in place; report VFP support to userspace.
  		 */
  		elf_hwcap |= HWCAP_VFP;

  #ifdef CONFIG_VFPv3

  		if (VFP_arch >= 2) {

  			elf_hwcap |= HWCAP_VFPv3;
  
  			/*
  			 * Check for VFPv3 D16. CPUs in this configuration
  			 * only have 16 x 64bit registers.
  			 */
  			if (((fmrx(MVFR0) & MVFR0_A_SIMD_MASK)) == 1)
  				elf_hwcap |= HWCAP_VFPv3D16;
  		}
  #endif

  		/*
  		 * Check for the presence of the Advanced SIMD
  		 * load/store instructions, integer and single

  		 * precision floating point operations. Only check
  		 * for NEON if the hardware has the MVFR registers.

  		 */

  		if ((read_cpuid_id() & 0x000f0000) == 0x000f0000) {

  #ifdef CONFIG_NEON

  			if ((fmrx(MVFR1) & 0x000fff00) == 0x00011100)
  				elf_hwcap |= HWCAP_NEON;

  #endif

  			if ((fmrx(MVFR1) & 0xf0000000) == 0x10000000)
  				elf_hwcap |= HWCAP_VFPv4;
  		}

  	}
  	return 0;
  }
  
  late_initcall(vfp_init);