/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2004, 2005 by Ralf Baechle
 * Copyright (C) 2005 by MIPS Technologies, Inc.
 */
#include <linux/oprofile.h>
#include <linux/interrupt.h>
#include <linux/smp.h>

#include "op_impl.h"

#define M_PERFCTL_EXL			(1UL    <<  0)
#define M_PERFCTL_KERNEL		(1UL    <<  1)
#define M_PERFCTL_SUPERVISOR		(1UL    <<  2)
#define M_PERFCTL_USER			(1UL    <<  3)
#define M_PERFCTL_INTERRUPT_ENABLE	(1UL    <<  4)
#define M_PERFCTL_EVENT(event)		((event) << 5)
#define M_PERFCTL_WIDE			(1UL    << 30)
#define M_PERFCTL_MORE			(1UL    << 31)

#define M_COUNTER_OVERFLOW		(1UL    << 31)

struct op_mips_model op_model_mipsxx;

static struct mipsxx_register_config {
	unsigned int control[4];
	unsigned int counter[4];
} reg;

/* Compute all of the registers in preparation for enabling profiling.  */

static void mipsxx_reg_setup(struct op_counter_config *ctr)
{
	unsigned int counters = op_model_mipsxx.num_counters;
	int i;

	/* Compute the performance counter control word.  */
	/* For now count kernel and user mode */
	for (i = 0; i < counters; i++) {
		reg.control[i] = 0;
		reg.counter[i] = 0;

		if (!ctr[i].enabled)
			continue;

		reg.control[i] = M_PERFCTL_EVENT(ctr[i].event) |
		                 M_PERFCTL_INTERRUPT_ENABLE;
		if (ctr[i].kernel)
			reg.control[i] |= M_PERFCTL_KERNEL;
		if (ctr[i].user)
			reg.control[i] |= M_PERFCTL_USER;
		if (ctr[i].exl)
			reg.control[i] |= M_PERFCTL_EXL;
		reg.counter[i] = 0x80000000 - ctr[i].count;
	}
}

/* Program all of the registers in preparation for enabling profiling.  */

static void mipsxx_cpu_setup (void *args)
{
	unsigned int counters = op_model_mipsxx.num_counters;

	switch (counters) {
	case 4:
		write_c0_perfctrl3(0);
		write_c0_perfcntr3(reg.counter[3]);
	case 3:
		write_c0_perfctrl2(0);
		write_c0_perfcntr2(reg.counter[2]);
	case 2:
		write_c0_perfctrl1(0);
		write_c0_perfcntr1(reg.counter[1]);
	case 1:
		write_c0_perfctrl0(0);
		write_c0_perfcntr0(reg.counter[0]);
	}
}

/* Start all counters on current CPU */
static void mipsxx_cpu_start(void *args)
{
	unsigned int counters = op_model_mipsxx.num_counters;

	switch (counters) {
	case 4:
		write_c0_perfctrl3(reg.control[3]);
	case 3:
		write_c0_perfctrl2(reg.control[2]);
	case 2:
		write_c0_perfctrl1(reg.control[1]);
	case 1:
		write_c0_perfctrl0(reg.control[0]);
	}
}

/* Stop all counters on current CPU */
static void mipsxx_cpu_stop(void *args)
{
	unsigned int counters = op_model_mipsxx.num_counters;

	switch (counters) {
	case 4:
		write_c0_perfctrl3(0);
	case 3:
		write_c0_perfctrl2(0);
	case 2:
		write_c0_perfctrl1(0);
	case 1:
		write_c0_perfctrl0(0);
	}
}

static void mipsxx_perfcount_handler(struct pt_regs *regs)
{
	unsigned int counters = op_model_mipsxx.num_counters;
	unsigned int control;
	unsigned int counter;

	switch (counters) {
#define HANDLE_COUNTER(n)						\
	case n + 1:							\
		control = read_c0_perfctrl ## n();			\
		counter = read_c0_perfcntr ## n();			\
		if ((control & M_PERFCTL_INTERRUPT_ENABLE) &&		\
		    (counter & M_COUNTER_OVERFLOW)) {			\
			oprofile_add_sample(regs, n);			\
			write_c0_perfcntr ## n(reg.counter[n]);		\
		}
	HANDLE_COUNTER(3)
	HANDLE_COUNTER(2)
	HANDLE_COUNTER(1)
	HANDLE_COUNTER(0)
	}
}

#define M_CONFIG1_PC	(1 << 4)

static inline int n_counters(void)
{
	if (!(read_c0_config1() & M_CONFIG1_PC))
		return 0;
	if (!(read_c0_perfctrl0() & M_PERFCTL_MORE))
		return 1;
	if (!(read_c0_perfctrl1() & M_PERFCTL_MORE))
		return 2;
	if (!(read_c0_perfctrl2() & M_PERFCTL_MORE))
		return 3;

	return 4;
}

static inline void reset_counters(int counters)
{
	switch (counters) {
	case 4:
		write_c0_perfctrl3(0);
		write_c0_perfcntr3(0);
	case 3:
		write_c0_perfctrl2(0);
		write_c0_perfcntr2(0);
	case 2:
		write_c0_perfctrl1(0);
		write_c0_perfcntr1(0);
	case 1:
		write_c0_perfctrl0(0);
		write_c0_perfcntr0(0);
	}
}

static int __init mipsxx_init(void)
{
	int counters;

	counters = n_counters();
	if (counters == 0)
		return -ENODEV;

	reset_counters(counters);

	op_model_mipsxx.num_counters = counters;
	switch (current_cpu_data.cputype) {
	case CPU_24K:
		op_model_mipsxx.cpu_type = "mips/24K";
		break;

	default:
		printk(KERN_ERR "Profiling unsupported for this CPU\n");

		return -ENODEV;
	}

	perf_irq = mipsxx_perfcount_handler;

	return 0;
}

static void mipsxx_exit(void)
{
	reset_counters(op_model_mipsxx.num_counters);

	perf_irq = null_perf_irq;
}

struct op_mips_model op_model_mipsxx = {
	.reg_setup	= mipsxx_reg_setup,
	.cpu_setup	= mipsxx_cpu_setup,
	.init		= mipsxx_init,
	.exit		= mipsxx_exit,
	.cpu_start	= mipsxx_cpu_start,
	.cpu_stop	= mipsxx_cpu_stop,
};