etm.c

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/*
 * linux/arch/arm/kernel/etm.c
 *
 * Driver for ARM's Embedded Trace Macrocell and Embedded Trace Buffer.
 *
 * Copyright (C) 2009 Nokia Corporation.
 * Alexander Shishkin
 *
 * 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/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/sysrq.h>
#include <linux/device.h>
#include <linux/clk.h>
#include <linux/amba/bus.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
#include <linux/miscdevice.h>
#include <linux/vmalloc.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <asm/hardware/coresight.h>
#include <asm/sections.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alexander Shishkin");

/*
 * ETM tracer state
 */
struct tracectx {
    unsigned int    etb_bufsz;
    void __iomem    *etb_regs;
    void __iomem    *etm_regs;
    unsigned long   flags;
    int     ncmppairs;
    int     etm_portsz;
    struct device   *dev;
    struct clk  *emu_clk;
    struct mutex    mutex;
};

static struct tracectx tracer;

static inline bool trace_isrunning(struct tracectx *t)
{
    return !!(t->flags & TRACER_RUNNING);
}

static int etm_setup_address_range(struct tracectx *t, int n,
        unsigned long start, unsigned long end, int exclude, int data)
{
    u32 flags = ETMAAT_ARM | ETMAAT_IGNCONTEXTID | ETMAAT_NSONLY | \
            ETMAAT_NOVALCMP;

    if (n < 1 || n > t->ncmppairs)
        return -EINVAL;

    /* comparators and ranges are numbered starting with 1 as opposed
     * to bits in a word */
    n--;

    if (data)
        flags |= ETMAAT_DLOADSTORE;
    else
        flags |= ETMAAT_IEXEC;

    /* first comparator for the range */
    etm_writel(t, flags, ETMR_COMP_ACC_TYPE(n * 2));
    etm_writel(t, start, ETMR_COMP_VAL(n * 2));

    /* second comparator is right next to it */
    etm_writel(t, flags, ETMR_COMP_ACC_TYPE(n * 2 + 1));
    etm_writel(t, end, ETMR_COMP_VAL(n * 2 + 1));

    flags = exclude ? ETMTE_INCLEXCL : 0;
    etm_writel(t, flags | (1 << n), ETMR_TRACEENCTRL);

    return 0;
}

static int trace_start(struct tracectx *t)
{
    u32 v;
    unsigned long timeout = TRACER_TIMEOUT;

    etb_unlock(t);

    etb_writel(t, 0, ETBR_FORMATTERCTRL);
    etb_writel(t, 1, ETBR_CTRL);

    etb_lock(t);

    /* configure etm */
    v = ETMCTRL_OPTS | ETMCTRL_PROGRAM | ETMCTRL_PORTSIZE(t->etm_portsz);

    if (t->flags & TRACER_CYCLE_ACC)
        v |= ETMCTRL_CYCLEACCURATE;

    etm_unlock(t);

    etm_writel(t, v, ETMR_CTRL);

    while (!(etm_readl(t, ETMR_CTRL) & ETMCTRL_PROGRAM) && --timeout)
        ;
    if (!timeout) {
        dev_dbg(t->dev, "Waiting for progbit to assert timed out\n");
        etm_lock(t);
        return -EFAULT;
    }

    etm_setup_address_range(t, 1, (unsigned long)_stext,
            (unsigned long)_etext, 0, 0);
    etm_writel(t, 0, ETMR_TRACEENCTRL2);
    etm_writel(t, 0, ETMR_TRACESSCTRL);
    etm_writel(t, 0x6f, ETMR_TRACEENEVT);

    v &= ~ETMCTRL_PROGRAM;
    v |= ETMCTRL_PORTSEL;

    etm_writel(t, v, ETMR_CTRL);

    timeout = TRACER_TIMEOUT;
    while (etm_readl(t, ETMR_CTRL) & ETMCTRL_PROGRAM && --timeout)
        ;
    if (!timeout) {
        dev_dbg(t->dev, "Waiting for progbit to deassert timed out\n");
        etm_lock(t);
        return -EFAULT;
    }

    etm_lock(t);

    t->flags |= TRACER_RUNNING;

    return 0;
}

static int trace_stop(struct tracectx *t)
{
    unsigned long timeout = TRACER_TIMEOUT;

    etm_unlock(t);

    etm_writel(t, 0x440, ETMR_CTRL);
    while (!(etm_readl(t, ETMR_CTRL) & ETMCTRL_PROGRAM) && --timeout)
        ;
    if (!timeout) {
        dev_dbg(t->dev, "Waiting for progbit to assert timed out\n");
        etm_lock(t);
        return -EFAULT;
    }

    etm_lock(t);

    etb_unlock(t);
    etb_writel(t, ETBFF_MANUAL_FLUSH, ETBR_FORMATTERCTRL);

    timeout = TRACER_TIMEOUT;
    while (etb_readl(t, ETBR_FORMATTERCTRL) &
            ETBFF_MANUAL_FLUSH && --timeout)
        ;
    if (!timeout) {
        dev_dbg(t->dev, "Waiting for formatter flush to commence "
                "timed out\n");
        etb_lock(t);
        return -EFAULT;
    }

    etb_writel(t, 0, ETBR_CTRL);

    etb_lock(t);

    t->flags &= ~TRACER_RUNNING;

    return 0;
}

static int etb_getdatalen(struct tracectx *t)
{
    u32 v;
    int rp, wp;

    v = etb_readl(t, ETBR_STATUS);

    if (v & 1)
        return t->etb_bufsz;

    rp = etb_readl(t, ETBR_READADDR);
    wp = etb_readl(t, ETBR_WRITEADDR);

    if (rp > wp) {
        etb_writel(t, 0, ETBR_READADDR);
        etb_writel(t, 0, ETBR_WRITEADDR);

        return 0;
    }

    return wp - rp;
}

/* sysrq+v will always stop the running trace and leave it at that */
static void etm_dump(void)
{
    struct tracectx *t = &tracer;
    u32 first = 0;
    int length;

    if (!t->etb_regs) {
        printk(KERN_INFO "No tracing hardware found\n");
        return;
    }

    if (trace_isrunning(t))
        trace_stop(t);

    etb_unlock(t);

    length = etb_getdatalen(t);

    if (length == t->etb_bufsz)
        first = etb_readl(t, ETBR_WRITEADDR);

    etb_writel(t, first, ETBR_READADDR);

    printk(KERN_INFO "Trace buffer contents length: %d\n", length);
    printk(KERN_INFO "--- ETB buffer begin ---\n");
    for (; length; length--)
        printk("%08x", cpu_to_be32(etb_readl(t, ETBR_READMEM)));
    printk(KERN_INFO "\n--- ETB buffer end ---\n");

    /* deassert the overflow bit */
    etb_writel(t, 1, ETBR_CTRL);
    etb_writel(t, 0, ETBR_CTRL);

    etb_writel(t, 0, ETBR_TRIGGERCOUNT);
    etb_writel(t, 0, ETBR_READADDR);
    etb_writel(t, 0, ETBR_WRITEADDR);

    etb_lock(t);
}

static void sysrq_etm_dump(int key)
{
    dev_dbg(tracer.dev, "Dumping ETB buffer\n");
    etm_dump();
}

static struct sysrq_key_op sysrq_etm_op = {
    .handler = sysrq_etm_dump,
    .help_msg = "ETM buffer dump",
    .action_msg = "etm",
};

static int etb_open(struct inode *inode, struct file *file)
{
    if (!tracer.etb_regs)
        return -ENODEV;

    file->private_data = &tracer;

    return nonseekable_open(inode, file);
}

static ssize_t etb_read(struct file *file, char __user *data,
        size_t len, loff_t *ppos)
{
    int total, i;
    long length;
    struct tracectx *t = file->private_data;
    u32 first = 0;
    u32 *buf;

    mutex_lock(&t->mutex);

    if (trace_isrunning(t)) {
        length = 0;
        goto out;
    }

    etb_unlock(t);

    total = etb_getdatalen(t);
    if (total == t->etb_bufsz)
        first = etb_readl(t, ETBR_WRITEADDR);

    etb_writel(t, first, ETBR_READADDR);

    length = min(total * 4, (int)len);
    buf = vmalloc(length);

    dev_dbg(t->dev, "ETB buffer length: %d\n", total);
    dev_dbg(t->dev, "ETB status reg: %x\n", etb_readl(t, ETBR_STATUS));
    for (i = 0; i < length / 4; i++)
        buf[i] = etb_readl(t, ETBR_READMEM);

    /* the only way to deassert overflow bit in ETB status is this */
    etb_writel(t, 1, ETBR_CTRL);
    etb_writel(t, 0, ETBR_CTRL);

    etb_writel(t, 0, ETBR_WRITEADDR);
    etb_writel(t, 0, ETBR_READADDR);
    etb_writel(t, 0, ETBR_TRIGGERCOUNT);

    etb_lock(t);

    length -= copy_to_user(data, buf, length);
    vfree(buf);

out:
    mutex_unlock(&t->mutex);

    return length;
}

static int etb_release(struct inode *inode, struct file *file)
{
    /* there's nothing to do here, actually */
    return 0;
}

static const struct file_operations etb_fops = {
    .owner = THIS_MODULE,
    .read = etb_read,
    .open = etb_open,
    .release = etb_release,
    .llseek = no_llseek,
};

static struct miscdevice etb_miscdev = {
    .name = "tracebuf",
    .minor = 0,
    .fops = &etb_fops,
};

static int __devinit etb_probe(struct amba_device *dev, const struct amba_id *id)
{
    struct tracectx *t = &tracer;
    int ret = 0;

    ret = amba_request_regions(dev, NULL);
    if (ret)
        goto out;

    t->etb_regs = ioremap_nocache(dev->res.start, resource_size(&dev->res));
    if (!t->etb_regs) {
        ret = -ENOMEM;
        goto out_release;
    }

    amba_set_drvdata(dev, t);

    etb_miscdev.parent = &dev->dev;

    ret = misc_register(&etb_miscdev);
    if (ret)
        goto out_unmap;

    t->emu_clk = clk_get(&dev->dev, "emu_src_ck");
    if (IS_ERR(t->emu_clk)) {
        dev_dbg(&dev->dev, "Failed to obtain emu_src_ck.\n");
        return -EFAULT;
    }

    clk_enable(t->emu_clk);

    etb_unlock(t);
    t->etb_bufsz = etb_readl(t, ETBR_DEPTH);
    dev_dbg(&dev->dev, "Size: %x\n", t->etb_bufsz);

    /* make sure trace capture is disabled */
    etb_writel(t, 0, ETBR_CTRL);
    etb_writel(t, 0x1000, ETBR_FORMATTERCTRL);
    etb_lock(t);

    dev_dbg(&dev->dev, "ETB AMBA driver initialized.\n");

out:
    return ret;

out_unmap:
    amba_set_drvdata(dev, NULL);
    iounmap(t->etb_regs);

out_release:
    amba_release_regions(dev);

    return ret;
}

static int etb_remove(struct amba_device *dev)
{
    struct tracectx *t = amba_get_drvdata(dev);

    amba_set_drvdata(dev, NULL);

    iounmap(t->etb_regs);
    t->etb_regs = NULL;

    clk_disable(t->emu_clk);
    clk_put(t->emu_clk);

    amba_release_regions(dev);

    return 0;
}

static struct amba_id etb_ids[] = {
    {
        .id = 0x0003b907,
        .mask   = 0x0007ffff,
    },
    { 0, 0 },
};

static struct amba_driver etb_driver = {
    .drv        = {
        .name   = "etb",
        .owner  = THIS_MODULE,
    },
    .probe      = etb_probe,
    .remove     = etb_remove,
    .id_table   = etb_ids,
};

/* use a sysfs file "trace_running" to start/stop tracing */
static ssize_t trace_running_show(struct kobject *kobj,
                  struct kobj_attribute *attr,
                  char *buf)
{
    return sprintf(buf, "%x\n", trace_isrunning(&tracer));
}

static ssize_t trace_running_store(struct kobject *kobj,
                   struct kobj_attribute *attr,
                   const char *buf, size_t n)
{
    unsigned int value;
    int ret;

    if (sscanf(buf, "%u", &value) != 1)
        return -EINVAL;

    mutex_lock(&tracer.mutex);
    ret = value ? trace_start(&tracer) : trace_stop(&tracer);
    mutex_unlock(&tracer.mutex);

    return ret ? : n;
}

static struct kobj_attribute trace_running_attr =
    __ATTR(trace_running, 0644, trace_running_show, trace_running_store);

static ssize_t trace_info_show(struct kobject *kobj,
                  struct kobj_attribute *attr,
                  char *buf)
{
    u32 etb_wa, etb_ra, etb_st, etb_fc, etm_ctrl, etm_st;
    int datalen;

    etb_unlock(&tracer);
    datalen = etb_getdatalen(&tracer);
    etb_wa = etb_readl(&tracer, ETBR_WRITEADDR);
    etb_ra = etb_readl(&tracer, ETBR_READADDR);
    etb_st = etb_readl(&tracer, ETBR_STATUS);
    etb_fc = etb_readl(&tracer, ETBR_FORMATTERCTRL);
    etb_lock(&tracer);

    etm_unlock(&tracer);
    etm_ctrl = etm_readl(&tracer, ETMR_CTRL);
    etm_st = etm_readl(&tracer, ETMR_STATUS);
    etm_lock(&tracer);

    return sprintf(buf, "Trace buffer len: %d\nComparator pairs: %d\n"
            "ETBR_WRITEADDR:\t%08x\n"
            "ETBR_READADDR:\t%08x\n"
            "ETBR_STATUS:\t%08x\n"
            "ETBR_FORMATTERCTRL:\t%08x\n"
            "ETMR_CTRL:\t%08x\n"
            "ETMR_STATUS:\t%08x\n",
            datalen,
            tracer.ncmppairs,
            etb_wa,
            etb_ra,
            etb_st,
            etb_fc,
            etm_ctrl,
            etm_st
            );
}

static struct kobj_attribute trace_info_attr =
    __ATTR(trace_info, 0444, trace_info_show, NULL);

static ssize_t trace_mode_show(struct kobject *kobj,
                  struct kobj_attribute *attr,
                  char *buf)
{
    return sprintf(buf, "%d %d\n",
            !!(tracer.flags & TRACER_CYCLE_ACC),
            tracer.etm_portsz);
}

static ssize_t trace_mode_store(struct kobject *kobj,
                   struct kobj_attribute *attr,
                   const char *buf, size_t n)
{
    unsigned int cycacc, portsz;

    if (sscanf(buf, "%u %u", &cycacc, &portsz) != 2)
        return -EINVAL;

    mutex_lock(&tracer.mutex);
    if (cycacc)
        tracer.flags |= TRACER_CYCLE_ACC;
    else
        tracer.flags &= ~TRACER_CYCLE_ACC;

    tracer.etm_portsz = portsz & 0x0f;
    mutex_unlock(&tracer.mutex);

    return n;
}

static struct kobj_attribute trace_mode_attr =
    __ATTR(trace_mode, 0644, trace_mode_show, trace_mode_store);

static int __devinit etm_probe(struct amba_device *dev, const struct amba_id *id)
{
    struct tracectx *t = &tracer;
    int ret = 0;

    if (t->etm_regs) {
        dev_dbg(&dev->dev, "ETM already initialized\n");
        ret = -EBUSY;
        goto out;
    }

    ret = amba_request_regions(dev, NULL);
    if (ret)
        goto out;

    t->etm_regs = ioremap_nocache(dev->res.start, resource_size(&dev->res));
    if (!t->etm_regs) {
        ret = -ENOMEM;
        goto out_release;
    }

    amba_set_drvdata(dev, t);

    mutex_init(&t->mutex);
    t->dev = &dev->dev;
    t->flags = TRACER_CYCLE_ACC;
    t->etm_portsz = 1;

    etm_unlock(t);
    (void)etm_readl(t, ETMMR_PDSR);
    /* dummy first read */
    (void)etm_readl(&tracer, ETMMR_OSSRR);

    t->ncmppairs = etm_readl(t, ETMR_CONFCODE) & 0xf;
    etm_writel(t, 0x440, ETMR_CTRL);
    etm_lock(t);

    ret = sysfs_create_file(&dev->dev.kobj,
            &trace_running_attr.attr);
    if (ret)
        goto out_unmap;

    /* failing to create any of these two is not fatal */
    ret = sysfs_create_file(&dev->dev.kobj, &trace_info_attr.attr);
    if (ret)
        dev_dbg(&dev->dev, "Failed to create trace_info in sysfs\n");

    ret = sysfs_create_file(&dev->dev.kobj, &trace_mode_attr.attr);
    if (ret)
        dev_dbg(&dev->dev, "Failed to create trace_mode in sysfs\n");

    dev_dbg(t->dev, "ETM AMBA driver initialized.\n");

out:
    return ret;

out_unmap:
    amba_set_drvdata(dev, NULL);
    iounmap(t->etm_regs);

out_release:
    amba_release_regions(dev);

    return ret;
}

static int etm_remove(struct amba_device *dev)
{
    struct tracectx *t = amba_get_drvdata(dev);

    amba_set_drvdata(dev, NULL);

    iounmap(t->etm_regs);
    t->etm_regs = NULL;

    amba_release_regions(dev);

    sysfs_remove_file(&dev->dev.kobj, &trace_running_attr.attr);
    sysfs_remove_file(&dev->dev.kobj, &trace_info_attr.attr);
    sysfs_remove_file(&dev->dev.kobj, &trace_mode_attr.attr);

    return 0;
}

static struct amba_id etm_ids[] = {
    {
        .id = 0x0003b921,
        .mask   = 0x0007ffff,
    },
    { 0, 0 },
};

static struct amba_driver etm_driver = {
    .drv        = {
        .name   = "etm",
        .owner  = THIS_MODULE,
    },
    .probe      = etm_probe,
    .remove     = etm_remove,
    .id_table   = etm_ids,
};

static int __init etm_init(void)
{
    int retval;

    retval = amba_driver_register(&etb_driver);
    if (retval) {
        printk(KERN_ERR "Failed to register etb\n");
        return retval;
    }

    retval = amba_driver_register(&etm_driver);
    if (retval) {
        amba_driver_unregister(&etb_driver);
        printk(KERN_ERR "Failed to probe etm\n");
        return retval;
    }

    /* not being able to install this handler is not fatal */
    (void)register_sysrq_key('v', &sysrq_etm_op);

    return 0;
}

device_initcall(etm_init);