/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Copyright (C) 2001, 2002, 2003 Broadcom Corporation
 * Copyright (C) 2007 Ralf Baechle <ralf@linux-mips.org>
 * Copyright (C) 2007 MIPS Technologies, Inc.
 *    written by Ralf Baechle <ralf@linux-mips.org>
 */

#undef DEBUG

#include <linux/device.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/vmalloc.h>
#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <asm/io.h>
#include <asm/sibyte/sb1250.h>

#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
#include <asm/sibyte/bcm1480_regs.h>
#include <asm/sibyte/bcm1480_scd.h>
#include <asm/sibyte/bcm1480_int.h>
#elif defined(CONFIG_SIBYTE_SB1250) || defined(CONFIG_SIBYTE_BCM112X)
#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_scd.h>
#include <asm/sibyte/sb1250_int.h>
#else
#error invalid SiByte UART configuration
#endif

#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
#undef K_INT_TRACE_FREEZE
#define K_INT_TRACE_FREEZE K_BCM1480_INT_TRACE_FREEZE
#undef K_INT_PERF_CNT
#define K_INT_PERF_CNT K_BCM1480_INT_PERF_CNT
#endif

#include <linux/uaccess.h>

#define SBPROF_TB_MAJOR 240

typedef u64 tb_sample_t[6*256];

enum open_status {
        SB_CLOSED,
        SB_OPENING,
        SB_OPEN
};

struct sbprof_tb {
        wait_queue_head_t       tb_sync;
        wait_queue_head_t       tb_read;
        struct mutex            lock;
        enum open_status        open;
        tb_sample_t             *sbprof_tbbuf;
        int                     next_tb_sample;

        volatile int            tb_enable;
        volatile int            tb_armed;

};

static struct sbprof_tb sbp;

#define MAX_SAMPLE_BYTES (24*1024*1024)
#define MAX_TBSAMPLE_BYTES (12*1024*1024)

#define MAX_SAMPLES (MAX_SAMPLE_BYTES/sizeof(u_int32_t))
#define TB_SAMPLE_SIZE (sizeof(tb_sample_t))
#define MAX_TB_SAMPLES (MAX_TBSAMPLE_BYTES/TB_SAMPLE_SIZE)

/* ioctls */
#define SBPROF_ZBSTART          _IOW('s', 0, int)
#define SBPROF_ZBSTOP           _IOW('s', 1, int)
#define SBPROF_ZBWAITFULL       _IOW('s', 2, int)

/*
 * Routines for using 40-bit SCD cycle counter
 *
 * Client responsible for either handling interrupts or making sure
 * the cycles counter never saturates, e.g., by doing
 * zclk_timer_init(0) at least every 2^40 - 1 ZCLKs.
 */

/*
 * Configures SCD counter 0 to count ZCLKs starting from val;
 * Configures SCD counters1,2,3 to count nothing.
 * Must not be called while gathering ZBbus profiles.
 */

#define zclk_timer_init(val) \
  __asm__ __volatile__ (".set push;" \
                        ".set mips64;" \
                        "la   $8, 0xb00204c0;" /* SCD perf_cnt_cfg */ \
                        "sd   %0, 0x10($8);"   /* write val to counter0 */ \
                        "sd   %1, 0($8);"      /* config counter0 for zclks*/ \
                        ".set pop" \
                        : /* no outputs */ \
                                                     /* enable, counter0 */ \
                        : /* inputs */ "r"(val), "r" ((1ULL << 33) | 1ULL) \
                        : /* modifies */ "$8" )


/* Reads SCD counter 0 and puts result in value
   unsigned long long val; */
#define zclk_get(val) \
  __asm__ __volatile__ (".set push;" \
                        ".set mips64;" \
                        "la   $8, 0xb00204c0;" /* SCD perf_cnt_cfg */ \
                        "ld   %0, 0x10($8);"   /* write val to counter0 */ \
                        ".set pop" \
                        : /* outputs */ "=r"(val) \
                        : /* inputs */ \
                        : /* modifies */ "$8" )

#define DEVNAME "sb_tbprof"

#define TB_FULL (sbp.next_tb_sample == MAX_TB_SAMPLES)

/*
 * Support for ZBbus sampling using the trace buffer
 *
 * We use the SCD performance counter interrupt, caused by a Zclk counter
 * overflow, to trigger the start of tracing.
 *
 * We set the trace buffer to sample everything and freeze on
 * overflow.
 *
 * We map the interrupt for trace_buffer_freeze to handle it on CPU 0.
 *
 */

static u64 tb_period;

static void arm_tb(void)
{
        u64 scdperfcnt;
        u64 next = (1ULL << 40) - tb_period;
        u64 tb_options = M_SCD_TRACE_CFG_FREEZE_FULL;

        /*
         * Generate an SCD_PERFCNT interrupt in TB_PERIOD Zclks to
         * trigger start of trace.  XXX vary sampling period
         */
        __raw_writeq(0, IOADDR(A_SCD_PERF_CNT_1));
        scdperfcnt = __raw_readq(IOADDR(A_SCD_PERF_CNT_CFG));

        /*
         * Unfortunately, in Pass 2 we must clear all counters to knock down
         * a previous interrupt request.  This means that bus profiling
         * requires ALL of the SCD perf counters.
         */
#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
        __raw_writeq((scdperfcnt & ~M_SPC_CFG_SRC1) |
                                                /* keep counters 0,2,3,4,5,6,7 as is */
                     V_SPC_CFG_SRC1(1),         /* counter 1 counts cycles */
                     IOADDR(A_BCM1480_SCD_PERF_CNT_CFG0));
        __raw_writeq(
                     M_SPC_CFG_ENABLE |         /* enable counting */
                     M_SPC_CFG_CLEAR |          /* clear all counters */
                     V_SPC_CFG_SRC1(1),         /* counter 1 counts cycles */
                     IOADDR(A_BCM1480_SCD_PERF_CNT_CFG1));
#else
        __raw_writeq((scdperfcnt & ~M_SPC_CFG_SRC1) |
                                                /* keep counters 0,2,3 as is */
                     M_SPC_CFG_ENABLE |         /* enable counting */
                     M_SPC_CFG_CLEAR |          /* clear all counters */
                     V_SPC_CFG_SRC1(1),         /* counter 1 counts cycles */
                     IOADDR(A_SCD_PERF_CNT_CFG));
#endif
        __raw_writeq(next, IOADDR(A_SCD_PERF_CNT_1));
        /* Reset the trace buffer */
        __raw_writeq(M_SCD_TRACE_CFG_RESET, IOADDR(A_SCD_TRACE_CFG));
#if 0 && defined(M_SCD_TRACE_CFG_FORCECNT)
        /* XXXKW may want to expose control to the data-collector */
        tb_options |= M_SCD_TRACE_CFG_FORCECNT;
#endif
        __raw_writeq(tb_options, IOADDR(A_SCD_TRACE_CFG));
        sbp.tb_armed = 1;
}

static irqreturn_t sbprof_tb_intr(int irq, void *dev_id)
{
        int i;

        pr_debug(DEVNAME ": tb_intr\n");

        if (sbp.next_tb_sample < MAX_TB_SAMPLES) {
                /* XXX should use XKPHYS to make writes bypass L2 */
                u64 *p = sbp.sbprof_tbbuf[sbp.next_tb_sample++];
                /* Read out trace */
                __raw_writeq(M_SCD_TRACE_CFG_START_READ,
                             IOADDR(A_SCD_TRACE_CFG));
                __asm__ __volatile__ ("sync" : : : "memory");
                /* Loop runs backwards because bundles are read out in reverse order */
                for (i = 256 * 6; i > 0; i -= 6) {
                        /* Subscripts decrease to put bundle in the order */
                        /*   t0 lo, t0 hi, t1 lo, t1 hi, t2 lo, t2 hi */
                        p[i - 1] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
                        /* read t2 hi */
                        p[i - 2] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
                        /* read t2 lo */
                        p[i - 3] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
                        /* read t1 hi */
                        p[i - 4] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
                        /* read t1 lo */
                        p[i - 5] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
                        /* read t0 hi */
                        p[i - 6] = __raw_readq(IOADDR(A_SCD_TRACE_READ));
                        /* read t0 lo */
                }
                if (!sbp.tb_enable) {
                        pr_debug(DEVNAME ": tb_intr shutdown\n");
                        __raw_writeq(M_SCD_TRACE_CFG_RESET,
                                     IOADDR(A_SCD_TRACE_CFG));
                        sbp.tb_armed = 0;
                        wake_up_interruptible(&sbp.tb_sync);
                } else {
                        /* knock down current interrupt and get another one later */
                        arm_tb();
                }
        } else {
                /* No more trace buffer samples */
                pr_debug(DEVNAME ": tb_intr full\n");
                __raw_writeq(M_SCD_TRACE_CFG_RESET, IOADDR(A_SCD_TRACE_CFG));
                sbp.tb_armed = 0;
                if (!sbp.tb_enable)
                        wake_up_interruptible(&sbp.tb_sync);
                wake_up_interruptible(&sbp.tb_read);
        }
        return IRQ_HANDLED;
}

static irqreturn_t sbprof_pc_intr(int irq, void *dev_id)
{
        printk(DEVNAME ": unexpected pc_intr");
        return IRQ_NONE;
}

/*
 * Requires: Already called zclk_timer_init with a value that won't
 *           saturate 40 bits.  No subsequent use of SCD performance counters
 *           or trace buffer.
 */

static int sbprof_zbprof_start(struct file *filp)
{
        u64 scdperfcnt;
        int err;

        if (xchg(&sbp.tb_enable, 1))
                return -EBUSY;

        pr_debug(DEVNAME ": starting\n");

        sbp.next_tb_sample = 0;
        filp->f_pos = 0;

        err = request_irq(K_INT_TRACE_FREEZE, sbprof_tb_intr, 0,
                          DEVNAME " trace freeze", &sbp);
        if (err)
                return -EBUSY;

        /* Make sure there isn't a perf-cnt interrupt waiting */
        scdperfcnt = __raw_readq(IOADDR(A_SCD_PERF_CNT_CFG));
        /* Disable and clear counters, override SRC_1 */
        __raw_writeq((scdperfcnt & ~(M_SPC_CFG_SRC1 | M_SPC_CFG_ENABLE)) |
                     M_SPC_CFG_ENABLE | M_SPC_CFG_CLEAR | V_SPC_CFG_SRC1(1),
                     IOADDR(A_SCD_PERF_CNT_CFG));

        /*
         * We grab this interrupt to prevent others from trying to use
         * it, even though we don't want to service the interrupts
         * (they only feed into the trace-on-interrupt mechanism)
         */
        if (request_irq(K_INT_PERF_CNT, sbprof_pc_intr, 0, DEVNAME " scd perfcnt", &sbp)) {
                free_irq(K_INT_TRACE_FREEZE, &sbp);
                return -EBUSY;
        }

        /*
         * I need the core to mask these, but the interrupt mapper to
         *  pass them through.  I am exploiting my knowledge that
         *  cp0_status masks out IP[5]. krw
         */
#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
        __raw_writeq(K_BCM1480_INT_MAP_I3,
                     IOADDR(A_BCM1480_IMR_REGISTER(0, R_BCM1480_IMR_INTERRUPT_MAP_BASE_L) +
                            ((K_BCM1480_INT_PERF_CNT & 0x3f) << 3)));
#else
        __raw_writeq(K_INT_MAP_I3,
                     IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_MAP_BASE) +
                            (K_INT_PERF_CNT << 3)));
#endif

        /* Initialize address traps */
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_0));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_1));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_2));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_UP_3));

        __raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_0));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_1));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_2));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_DOWN_3));

        __raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_0));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_1));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_2));
        __raw_writeq(0, IOADDR(A_ADDR_TRAP_CFG_3));

        /* Initialize Trace Event 0-7 */
        /*                              when interrupt  */
        __raw_writeq(M_SCD_TREVT_INTERRUPT, IOADDR(A_SCD_TRACE_EVENT_0));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_1));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_2));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_3));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_4));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_5));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_6));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_EVENT_7));

        /* Initialize Trace Sequence 0-7 */
        /*                                   Start on event 0 (interrupt) */
        __raw_writeq(V_SCD_TRSEQ_FUNC_START | 0x0fff,
                     IOADDR(A_SCD_TRACE_SEQUENCE_0));
        /*                        dsamp when d used | asamp when a used */
        __raw_writeq(M_SCD_TRSEQ_ASAMPLE | M_SCD_TRSEQ_DSAMPLE |
                     K_SCD_TRSEQ_TRIGGER_ALL,
                     IOADDR(A_SCD_TRACE_SEQUENCE_1));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_2));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_3));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_4));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_5));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_6));
        __raw_writeq(0, IOADDR(A_SCD_TRACE_SEQUENCE_7));

        /* Now indicate the PERF_CNT interrupt as a trace-relevant interrupt */
#if defined(CONFIG_SIBYTE_BCM1x55) || defined(CONFIG_SIBYTE_BCM1x80)
        __raw_writeq(1ULL << (K_BCM1480_INT_PERF_CNT & 0x3f),
                     IOADDR(A_BCM1480_IMR_REGISTER(0, R_BCM1480_IMR_INTERRUPT_TRACE_L)));
#else
        __raw_writeq(1ULL << K_INT_PERF_CNT,
                     IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_TRACE)));
#endif
        arm_tb();

        pr_debug(DEVNAME ": done starting\n");

        return 0;
}

static int sbprof_zbprof_stop(void)
{
        int err = 0;

        pr_debug(DEVNAME ": stopping\n");

        if (sbp.tb_enable) {
                /*
                 * XXXKW there is a window here where the intr handler may run,
                 * see the disable, and do the wake_up before this sleep
                 * happens.
                 */
                pr_debug(DEVNAME ": wait for disarm\n");
                err = wait_event_interruptible(sbp.tb_sync, !sbp.tb_armed);
                pr_debug(DEVNAME ": disarm complete, stat %d\n", err);

                if (err)
                        return err;

                sbp.tb_enable = 0;
                free_irq(K_INT_TRACE_FREEZE, &sbp);
                free_irq(K_INT_PERF_CNT, &sbp);
        }

        pr_debug(DEVNAME ": done stopping\n");

        return err;
}

static int sbprof_tb_open(struct inode *inode, struct file *filp)
{
        int minor;

        minor = iminor(inode);
        if (minor != 0)
                return -ENODEV;

        if (xchg(&sbp.open, SB_OPENING) != SB_CLOSED)
                return -EBUSY;

        memset(&sbp, 0, sizeof(struct sbprof_tb));
        sbp.sbprof_tbbuf = vzalloc(MAX_TBSAMPLE_BYTES);
        if (!sbp.sbprof_tbbuf) {
                sbp.open = SB_CLOSED;
                wmb();
                return -ENOMEM;
        }

        init_waitqueue_head(&sbp.tb_sync);
        init_waitqueue_head(&sbp.tb_read);
        mutex_init(&sbp.lock);

        sbp.open = SB_OPEN;
        wmb();

        return 0;
}

static int sbprof_tb_release(struct inode *inode, struct file *filp)
{
        int minor;

        minor = iminor(inode);
        if (minor != 0 || sbp.open != SB_CLOSED)
                return -ENODEV;

        mutex_lock(&sbp.lock);

        if (sbp.tb_armed || sbp.tb_enable)
                sbprof_zbprof_stop();

        vfree(sbp.sbprof_tbbuf);
        sbp.open = SB_CLOSED;
        wmb();

        mutex_unlock(&sbp.lock);

        return 0;
}

static ssize_t sbprof_tb_read(struct file *filp, char *buf,
                              size_t size, loff_t *offp)
{
        int cur_sample, sample_off, cur_count, sample_left;
        char *src;
        int   count   =  0;
        char *dest    =  buf;
        long  cur_off = *offp;

        if (!access_ok(VERIFY_WRITE, buf, size))
                return -EFAULT;

        mutex_lock(&sbp.lock);

        count = 0;
        cur_sample = cur_off / TB_SAMPLE_SIZE;
        sample_off = cur_off % TB_SAMPLE_SIZE;
        sample_left = TB_SAMPLE_SIZE - sample_off;

        while (size && (cur_sample < sbp.next_tb_sample)) {
                int err;

                cur_count = size < sample_left ? size : sample_left;
                src = (char *)(((long)sbp.sbprof_tbbuf[cur_sample])+sample_off);
                err = __copy_to_user(dest, src, cur_count);
                if (err) {
                        *offp = cur_off + cur_count - err;
                        mutex_unlock(&sbp.lock);
                        return err;
                }
                pr_debug(DEVNAME ": read from sample %d, %d bytes\n",
                         cur_sample, cur_count);
                size -= cur_count;
                sample_left -= cur_count;
                if (!sample_left) {
                        cur_sample++;
                        sample_off = 0;
                        sample_left = TB_SAMPLE_SIZE;
                } else {
                        sample_off += cur_count;
                }
                cur_off += cur_count;
                dest += cur_count;
                count += cur_count;
        }
        *offp = cur_off;
        mutex_unlock(&sbp.lock);

        return count;
}

static long sbprof_tb_ioctl(struct file *filp,
                            unsigned int command,
                            unsigned long arg)
{
        int err = 0;

        switch (command) {
        case SBPROF_ZBSTART:
                mutex_lock(&sbp.lock);
                err = sbprof_zbprof_start(filp);
                mutex_unlock(&sbp.lock);
                break;

        case SBPROF_ZBSTOP:
                mutex_lock(&sbp.lock);
                err = sbprof_zbprof_stop();
                mutex_unlock(&sbp.lock);
                break;

        case SBPROF_ZBWAITFULL: {
                err = wait_event_interruptible(sbp.tb_read, TB_FULL);
                if (err)
                        break;

                err = put_user(TB_FULL, (int *) arg);
                break;
        }

        default:
                err = -EINVAL;
                break;
        }

        return err;
}

static const struct file_operations sbprof_tb_fops = {
        .owner          = THIS_MODULE,
        .open           = sbprof_tb_open,
        .release        = sbprof_tb_release,
        .read           = sbprof_tb_read,
        .unlocked_ioctl = sbprof_tb_ioctl,
        .compat_ioctl   = sbprof_tb_ioctl,
        .mmap           = NULL,
        .llseek         = default_llseek,
};

static struct class *tb_class;
static struct device *tb_dev;

static int __init sbprof_tb_init(void)
{
        struct device *dev;
        struct class *tbc;
        int err;

        if (register_chrdev(SBPROF_TB_MAJOR, DEVNAME, &sbprof_tb_fops)) {
                printk(KERN_WARNING DEVNAME ": initialization failed (dev %d)\n",
                       SBPROF_TB_MAJOR);
                return -EIO;
        }

        tbc = class_create(THIS_MODULE, "sb_tracebuffer");
        if (IS_ERR(tbc)) {
                err = PTR_ERR(tbc);
                goto out_chrdev;
        }

        tb_class = tbc;

        dev = device_create(tbc, NULL, MKDEV(SBPROF_TB_MAJOR, 0), NULL, "tb");
        if (IS_ERR(dev)) {
                err = PTR_ERR(dev);
                goto out_class;
        }
        tb_dev = dev;

        sbp.open = SB_CLOSED;
        wmb();
        tb_period = zbbus_mhz * 10000LL;
        pr_info(DEVNAME ": initialized - tb_period = %lld\n",
                (long long) tb_period);
        return 0;

out_class:
        class_destroy(tb_class);
out_chrdev:
        unregister_chrdev(SBPROF_TB_MAJOR, DEVNAME);

        return err;
}

static void __exit sbprof_tb_cleanup(void)
{
        device_destroy(tb_class, MKDEV(SBPROF_TB_MAJOR, 0));
        unregister_chrdev(SBPROF_TB_MAJOR, DEVNAME);
        class_destroy(tb_class);
}

module_init(sbprof_tb_init);
module_exit(sbprof_tb_cleanup);

MODULE_ALIAS_CHARDEV_MAJOR(SBPROF_TB_MAJOR);
MODULE_AUTHOR("Ralf Baechle <ralf@linux-mips.org>");
MODULE_LICENSE("GPL");