Merge tag 'trace-printf-v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/trace...

[drm/drm-misc.git] / drivers / hwtracing / coresight / coresight-etb10.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (c) 2011-2012, The Linux Foundation. All rights reserved.
 *
 * Description: CoreSight Embedded Trace Buffer driver
 */

#include <linux/atomic.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
#include <linux/device.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/fs.h>
#include <linux/miscdevice.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/pm_runtime.h>
#include <linux/seq_file.h>
#include <linux/coresight.h>
#include <linux/amba/bus.h>
#include <linux/clk.h>
#include <linux/circ_buf.h>
#include <linux/mm.h>
#include <linux/perf_event.h>


#include "coresight-priv.h"
#include "coresight-etm-perf.h"

#define ETB_RAM_DEPTH_REG       0x004
#define ETB_STATUS_REG          0x00c
#define ETB_RAM_READ_DATA_REG   0x010
#define ETB_RAM_READ_POINTER    0x014
#define ETB_RAM_WRITE_POINTER   0x018
#define ETB_TRG                 0x01c
#define ETB_CTL_REG             0x020
#define ETB_RWD_REG             0x024
#define ETB_FFSR                0x300
#define ETB_FFCR                0x304
#define ETB_ITMISCOP0           0xee0
#define ETB_ITTRFLINACK         0xee4
#define ETB_ITTRFLIN            0xee8
#define ETB_ITATBDATA0          0xeeC
#define ETB_ITATBCTR2           0xef0
#define ETB_ITATBCTR1           0xef4
#define ETB_ITATBCTR0           0xef8

/* register description */
/* STS - 0x00C */
#define ETB_STATUS_RAM_FULL     BIT(0)
/* CTL - 0x020 */
#define ETB_CTL_CAPT_EN         BIT(0)
/* FFCR - 0x304 */
#define ETB_FFCR_EN_FTC         BIT(0)
#define ETB_FFCR_FON_MAN        BIT(6)
#define ETB_FFCR_STOP_FI        BIT(12)
#define ETB_FFCR_STOP_TRIGGER   BIT(13)

#define ETB_FFCR_BIT            6
#define ETB_FFSR_BIT            1
#define ETB_FRAME_SIZE_WORDS    4

DEFINE_CORESIGHT_DEVLIST(etb_devs, "etb");

/**
 * struct etb_drvdata - specifics associated to an ETB component
 * @base:       memory mapped base address for this component.
 * @atclk:      optional clock for the core parts of the ETB.
 * @csdev:      component vitals needed by the framework.
 * @miscdev:    specifics to handle "/dev/xyz.etb" entry.
 * @spinlock:   only one at a time pls.
 * @reading:    synchronise user space access to etb buffer.
 * @pid:        Process ID of the process being monitored by the session
 *              that is using this component.
 * @buf:        area of memory where ETB buffer content gets sent.
 * @buffer_depth: size of @buf.
 * @trigger_cntr: amount of words to store after a trigger.
 */
struct etb_drvdata {
        void __iomem            *base;
        struct clk              *atclk;
        struct coresight_device *csdev;
        struct miscdevice       miscdev;
        spinlock_t              spinlock;
        local_t                 reading;
        pid_t                   pid;
        u8                      *buf;
        u32                     buffer_depth;
        u32                     trigger_cntr;
};

static int etb_set_buffer(struct coresight_device *csdev,
                          struct perf_output_handle *handle);

static inline unsigned int etb_get_buffer_depth(struct etb_drvdata *drvdata)
{
        return readl_relaxed(drvdata->base + ETB_RAM_DEPTH_REG);
}

static void __etb_enable_hw(struct etb_drvdata *drvdata)
{
        int i;
        u32 depth;

        CS_UNLOCK(drvdata->base);

        depth = drvdata->buffer_depth;
        /* reset write RAM pointer address */
        writel_relaxed(0x0, drvdata->base + ETB_RAM_WRITE_POINTER);
        /* clear entire RAM buffer */
        for (i = 0; i < depth; i++)
                writel_relaxed(0x0, drvdata->base + ETB_RWD_REG);

        /* reset write RAM pointer address */
        writel_relaxed(0x0, drvdata->base + ETB_RAM_WRITE_POINTER);
        /* reset read RAM pointer address */
        writel_relaxed(0x0, drvdata->base + ETB_RAM_READ_POINTER);

        writel_relaxed(drvdata->trigger_cntr, drvdata->base + ETB_TRG);
        writel_relaxed(ETB_FFCR_EN_FTC | ETB_FFCR_STOP_TRIGGER,
                       drvdata->base + ETB_FFCR);
        /* ETB trace capture enable */
        writel_relaxed(ETB_CTL_CAPT_EN, drvdata->base + ETB_CTL_REG);

        CS_LOCK(drvdata->base);
}

static int etb_enable_hw(struct etb_drvdata *drvdata)
{
        int rc = coresight_claim_device(drvdata->csdev);

        if (rc)
                return rc;

        __etb_enable_hw(drvdata);
        return 0;
}

static int etb_enable_sysfs(struct coresight_device *csdev)
{
        int ret = 0;
        unsigned long flags;
        struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

        spin_lock_irqsave(&drvdata->spinlock, flags);

        /* Don't messup with perf sessions. */
        if (coresight_get_mode(csdev) == CS_MODE_PERF) {
                ret = -EBUSY;
                goto out;
        }

        if (coresight_get_mode(csdev) == CS_MODE_DISABLED) {
                ret = etb_enable_hw(drvdata);
                if (ret)
                        goto out;

                coresight_set_mode(csdev, CS_MODE_SYSFS);
        }

        csdev->refcnt++;
out:
        spin_unlock_irqrestore(&drvdata->spinlock, flags);
        return ret;
}

static int etb_enable_perf(struct coresight_device *csdev, void *data)
{
        int ret = 0;
        pid_t pid;
        unsigned long flags;
        struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
        struct perf_output_handle *handle = data;
        struct cs_buffers *buf = etm_perf_sink_config(handle);

        spin_lock_irqsave(&drvdata->spinlock, flags);

        /* No need to continue if the component is already in used by sysFS. */
        if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
                ret = -EBUSY;
                goto out;
        }

        /* Get a handle on the pid of the process to monitor */
        pid = buf->pid;

        if (drvdata->pid != -1 && drvdata->pid != pid) {
                ret = -EBUSY;
                goto out;
        }

        /*
         * No HW configuration is needed if the sink is already in
         * use for this session.
         */
        if (drvdata->pid == pid) {
                csdev->refcnt++;
                goto out;
        }

        /*
         * We don't have an internal state to clean up if we fail to setup
         * the perf buffer. So we can perform the step before we turn the
         * ETB on and leave without cleaning up.
         */
        ret = etb_set_buffer(csdev, handle);
        if (ret)
                goto out;

        ret = etb_enable_hw(drvdata);
        if (!ret) {
                /* Associate with monitored process. */
                drvdata->pid = pid;
                coresight_set_mode(drvdata->csdev, CS_MODE_PERF);
                csdev->refcnt++;
        }

out:
        spin_unlock_irqrestore(&drvdata->spinlock, flags);
        return ret;
}

static int etb_enable(struct coresight_device *csdev, enum cs_mode mode,
                      void *data)
{
        int ret;

        switch (mode) {
        case CS_MODE_SYSFS:
                ret = etb_enable_sysfs(csdev);
                break;
        case CS_MODE_PERF:
                ret = etb_enable_perf(csdev, data);
                break;
        default:
                ret = -EINVAL;
                break;
        }

        if (ret)
                return ret;

        dev_dbg(&csdev->dev, "ETB enabled\n");
        return 0;
}

static void __etb_disable_hw(struct etb_drvdata *drvdata)
{
        u32 ffcr;
        struct device *dev = &drvdata->csdev->dev;
        struct csdev_access *csa = &drvdata->csdev->access;

        CS_UNLOCK(drvdata->base);

        ffcr = readl_relaxed(drvdata->base + ETB_FFCR);
        /* stop formatter when a stop has completed */
        ffcr |= ETB_FFCR_STOP_FI;
        writel_relaxed(ffcr, drvdata->base + ETB_FFCR);
        /* manually generate a flush of the system */
        ffcr |= ETB_FFCR_FON_MAN;
        writel_relaxed(ffcr, drvdata->base + ETB_FFCR);

        if (coresight_timeout(csa, ETB_FFCR, ETB_FFCR_BIT, 0)) {
                dev_err(dev,
                "timeout while waiting for completion of Manual Flush\n");
        }

        /* disable trace capture */
        writel_relaxed(0x0, drvdata->base + ETB_CTL_REG);

        if (coresight_timeout(csa, ETB_FFSR, ETB_FFSR_BIT, 1)) {
                dev_err(dev,
                        "timeout while waiting for Formatter to Stop\n");
        }

        CS_LOCK(drvdata->base);
}

static void etb_dump_hw(struct etb_drvdata *drvdata)
{
        bool lost = false;
        int i;
        u8 *buf_ptr;
        u32 read_data, depth;
        u32 read_ptr, write_ptr;
        u32 frame_off, frame_endoff;
        struct device *dev = &drvdata->csdev->dev;

        CS_UNLOCK(drvdata->base);

        read_ptr = readl_relaxed(drvdata->base + ETB_RAM_READ_POINTER);
        write_ptr = readl_relaxed(drvdata->base + ETB_RAM_WRITE_POINTER);

        frame_off = write_ptr % ETB_FRAME_SIZE_WORDS;
        frame_endoff = ETB_FRAME_SIZE_WORDS - frame_off;
        if (frame_off) {
                dev_err(dev,
                        "write_ptr: %lu not aligned to formatter frame size\n",
                        (unsigned long)write_ptr);
                dev_err(dev, "frameoff: %lu, frame_endoff: %lu\n",
                        (unsigned long)frame_off, (unsigned long)frame_endoff);
                write_ptr += frame_endoff;
        }

        if ((readl_relaxed(drvdata->base + ETB_STATUS_REG)
                      & ETB_STATUS_RAM_FULL) == 0) {
                writel_relaxed(0x0, drvdata->base + ETB_RAM_READ_POINTER);
        } else {
                writel_relaxed(write_ptr, drvdata->base + ETB_RAM_READ_POINTER);
                lost = true;
        }

        depth = drvdata->buffer_depth;
        buf_ptr = drvdata->buf;
        for (i = 0; i < depth; i++) {
                read_data = readl_relaxed(drvdata->base +
                                          ETB_RAM_READ_DATA_REG);
                *(u32 *)buf_ptr = read_data;
                buf_ptr += 4;
        }

        if (lost)
                coresight_insert_barrier_packet(drvdata->buf);

        if (frame_off) {
                buf_ptr -= (frame_endoff * 4);
                for (i = 0; i < frame_endoff; i++) {
                        *buf_ptr++ = 0x0;
                        *buf_ptr++ = 0x0;
                        *buf_ptr++ = 0x0;
                        *buf_ptr++ = 0x0;
                }
        }

        writel_relaxed(read_ptr, drvdata->base + ETB_RAM_READ_POINTER);

        CS_LOCK(drvdata->base);
}

static void etb_disable_hw(struct etb_drvdata *drvdata)
{
        __etb_disable_hw(drvdata);
        etb_dump_hw(drvdata);
        coresight_disclaim_device(drvdata->csdev);
}

static int etb_disable(struct coresight_device *csdev)
{
        struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);
        unsigned long flags;

        spin_lock_irqsave(&drvdata->spinlock, flags);

        csdev->refcnt--;
        if (csdev->refcnt) {
                spin_unlock_irqrestore(&drvdata->spinlock, flags);
                return -EBUSY;
        }

        /* Complain if we (somehow) got out of sync */
        WARN_ON_ONCE(coresight_get_mode(csdev) == CS_MODE_DISABLED);
        etb_disable_hw(drvdata);
        /* Dissociate from monitored process. */
        drvdata->pid = -1;
        coresight_set_mode(csdev, CS_MODE_DISABLED);
        spin_unlock_irqrestore(&drvdata->spinlock, flags);

        dev_dbg(&csdev->dev, "ETB disabled\n");
        return 0;
}

static void *etb_alloc_buffer(struct coresight_device *csdev,
                              struct perf_event *event, void **pages,
                              int nr_pages, bool overwrite)
{
        int node;
        struct cs_buffers *buf;

        node = (event->cpu == -1) ? NUMA_NO_NODE : cpu_to_node(event->cpu);

        buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
        if (!buf)
                return NULL;

        buf->pid = task_pid_nr(event->owner);
        buf->snapshot = overwrite;
        buf->nr_pages = nr_pages;
        buf->data_pages = pages;

        return buf;
}

static void etb_free_buffer(void *config)
{
        struct cs_buffers *buf = config;

        kfree(buf);
}

static int etb_set_buffer(struct coresight_device *csdev,
                          struct perf_output_handle *handle)
{
        int ret = 0;
        unsigned long head;
        struct cs_buffers *buf = etm_perf_sink_config(handle);

        if (!buf)
                return -EINVAL;

        /* wrap head around to the amount of space we have */
        head = handle->head & ((buf->nr_pages << PAGE_SHIFT) - 1);

        /* find the page to write to */
        buf->cur = head / PAGE_SIZE;

        /* and offset within that page */
        buf->offset = head % PAGE_SIZE;

        local_set(&buf->data_size, 0);

        return ret;
}

static unsigned long etb_update_buffer(struct coresight_device *csdev,
                              struct perf_output_handle *handle,
                              void *sink_config)
{
        bool lost = false;
        int i, cur;
        u8 *buf_ptr;
        const u32 *barrier;
        u32 read_ptr, write_ptr, capacity;
        u32 status, read_data;
        unsigned long offset, to_read = 0, flags;
        struct cs_buffers *buf = sink_config;
        struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

        if (!buf)
                return 0;

        capacity = drvdata->buffer_depth * ETB_FRAME_SIZE_WORDS;

        spin_lock_irqsave(&drvdata->spinlock, flags);

        /* Don't do anything if another tracer is using this sink */
        if (csdev->refcnt != 1)
                goto out;

        __etb_disable_hw(drvdata);
        CS_UNLOCK(drvdata->base);

        /* unit is in words, not bytes */
        read_ptr = readl_relaxed(drvdata->base + ETB_RAM_READ_POINTER);
        write_ptr = readl_relaxed(drvdata->base + ETB_RAM_WRITE_POINTER);

        /*
         * Entries should be aligned to the frame size.  If they are not
         * go back to the last alignment point to give decoding tools a
         * chance to fix things.
         */
        if (write_ptr % ETB_FRAME_SIZE_WORDS) {
                dev_err(&csdev->dev,
                        "write_ptr: %lu not aligned to formatter frame size\n",
                        (unsigned long)write_ptr);

                write_ptr &= ~(ETB_FRAME_SIZE_WORDS - 1);
                lost = true;
        }

        /*
         * Get a hold of the status register and see if a wrap around
         * has occurred.  If so adjust things accordingly.  Otherwise
         * start at the beginning and go until the write pointer has
         * been reached.
         */
        status = readl_relaxed(drvdata->base + ETB_STATUS_REG);
        if (status & ETB_STATUS_RAM_FULL) {
                lost = true;
                to_read = capacity;
                read_ptr = write_ptr;
        } else {
                to_read = CIRC_CNT(write_ptr, read_ptr, drvdata->buffer_depth);
                to_read *= ETB_FRAME_SIZE_WORDS;
        }

        /*
         * Make sure we don't overwrite data that hasn't been consumed yet.
         * It is entirely possible that the HW buffer has more data than the
         * ring buffer can currently handle.  If so adjust the start address
         * to take only the last traces.
         *
         * In snapshot mode we are looking to get the latest traces only and as
         * such, we don't care about not overwriting data that hasn't been
         * processed by user space.
         */
        if (!buf->snapshot && to_read > handle->size) {
                u32 mask = ~(ETB_FRAME_SIZE_WORDS - 1);

                /* The new read pointer must be frame size aligned */
                to_read = handle->size & mask;
                /*
                 * Move the RAM read pointer up, keeping in mind that
                 * everything is in frame size units.
                 */
                read_ptr = (write_ptr + drvdata->buffer_depth) -
                                        to_read / ETB_FRAME_SIZE_WORDS;
                /* Wrap around if need be*/
                if (read_ptr > (drvdata->buffer_depth - 1))
                        read_ptr -= drvdata->buffer_depth;
                /* let the decoder know we've skipped ahead */
                lost = true;
        }

        /*
         * Don't set the TRUNCATED flag in snapshot mode because 1) the
         * captured buffer is expected to be truncated and 2) a full buffer
         * prevents the event from being re-enabled by the perf core,
         * resulting in stale data being send to user space.
         */
        if (!buf->snapshot && lost)
                perf_aux_output_flag(handle, PERF_AUX_FLAG_TRUNCATED);

        /* finally tell HW where we want to start reading from */
        writel_relaxed(read_ptr, drvdata->base + ETB_RAM_READ_POINTER);

        cur = buf->cur;
        offset = buf->offset;
        barrier = coresight_barrier_pkt;

        for (i = 0; i < to_read; i += 4) {
                buf_ptr = buf->data_pages[cur] + offset;
                read_data = readl_relaxed(drvdata->base +
                                          ETB_RAM_READ_DATA_REG);
                if (lost && i < CORESIGHT_BARRIER_PKT_SIZE) {
                        read_data = *barrier;
                        barrier++;
                }

                *(u32 *)buf_ptr = read_data;
                buf_ptr += 4;

                offset += 4;
                if (offset >= PAGE_SIZE) {
                        offset = 0;
                        cur++;
                        /* wrap around at the end of the buffer */
                        cur &= buf->nr_pages - 1;
                }
        }

        /* reset ETB buffer for next run */
        writel_relaxed(0x0, drvdata->base + ETB_RAM_READ_POINTER);
        writel_relaxed(0x0, drvdata->base + ETB_RAM_WRITE_POINTER);

        /*
         * In snapshot mode we simply increment the head by the number of byte
         * that were written.  User space will figure out how many bytes to get
         * from the AUX buffer based on the position of the head.
         */
        if (buf->snapshot)
                handle->head += to_read;

        __etb_enable_hw(drvdata);
        CS_LOCK(drvdata->base);
out:
        spin_unlock_irqrestore(&drvdata->spinlock, flags);

        return to_read;
}

static const struct coresight_ops_sink etb_sink_ops = {
        .enable         = etb_enable,
        .disable        = etb_disable,
        .alloc_buffer   = etb_alloc_buffer,
        .free_buffer    = etb_free_buffer,
        .update_buffer  = etb_update_buffer,
};

static const struct coresight_ops etb_cs_ops = {
        .sink_ops       = &etb_sink_ops,
};

static void etb_dump(struct etb_drvdata *drvdata)
{
        unsigned long flags;

        spin_lock_irqsave(&drvdata->spinlock, flags);
        if (coresight_get_mode(drvdata->csdev) == CS_MODE_SYSFS) {
                __etb_disable_hw(drvdata);
                etb_dump_hw(drvdata);
                __etb_enable_hw(drvdata);
        }
        spin_unlock_irqrestore(&drvdata->spinlock, flags);

        dev_dbg(&drvdata->csdev->dev, "ETB dumped\n");
}

static int etb_open(struct inode *inode, struct file *file)
{
        struct etb_drvdata *drvdata = container_of(file->private_data,
                                                   struct etb_drvdata, miscdev);

        if (local_cmpxchg(&drvdata->reading, 0, 1))
                return -EBUSY;

        dev_dbg(&drvdata->csdev->dev, "%s: successfully opened\n", __func__);
        return 0;
}

static ssize_t etb_read(struct file *file, char __user *data,
                                size_t len, loff_t *ppos)
{
        u32 depth;
        struct etb_drvdata *drvdata = container_of(file->private_data,
                                                   struct etb_drvdata, miscdev);
        struct device *dev = &drvdata->csdev->dev;

        etb_dump(drvdata);

        depth = drvdata->buffer_depth;
        if (*ppos + len > depth * 4)
                len = depth * 4 - *ppos;

        if (copy_to_user(data, drvdata->buf + *ppos, len)) {
                dev_dbg(dev,
                        "%s: copy_to_user failed\n", __func__);
                return -EFAULT;
        }

        *ppos += len;

        dev_dbg(dev, "%s: %zu bytes copied, %d bytes left\n",
                __func__, len, (int)(depth * 4 - *ppos));
        return len;
}

static int etb_release(struct inode *inode, struct file *file)
{
        struct etb_drvdata *drvdata = container_of(file->private_data,
                                                   struct etb_drvdata, miscdev);
        local_set(&drvdata->reading, 0);

        dev_dbg(&drvdata->csdev->dev, "%s: released\n", __func__);
        return 0;
}

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

static struct attribute *coresight_etb_mgmt_attrs[] = {
        coresight_simple_reg32(rdp, ETB_RAM_DEPTH_REG),
        coresight_simple_reg32(sts, ETB_STATUS_REG),
        coresight_simple_reg32(rrp, ETB_RAM_READ_POINTER),
        coresight_simple_reg32(rwp, ETB_RAM_WRITE_POINTER),
        coresight_simple_reg32(trg, ETB_TRG),
        coresight_simple_reg32(ctl, ETB_CTL_REG),
        coresight_simple_reg32(ffsr, ETB_FFSR),
        coresight_simple_reg32(ffcr, ETB_FFCR),
        NULL,
};

static ssize_t trigger_cntr_show(struct device *dev,
                            struct device_attribute *attr, char *buf)
{
        struct etb_drvdata *drvdata = dev_get_drvdata(dev->parent);
        unsigned long val = drvdata->trigger_cntr;

        return sprintf(buf, "%#lx\n", val);
}

static ssize_t trigger_cntr_store(struct device *dev,
                             struct device_attribute *attr,
                             const char *buf, size_t size)
{
        int ret;
        unsigned long val;
        struct etb_drvdata *drvdata = dev_get_drvdata(dev->parent);

        ret = kstrtoul(buf, 16, &val);
        if (ret)
                return ret;

        drvdata->trigger_cntr = val;
        return size;
}
static DEVICE_ATTR_RW(trigger_cntr);

static struct attribute *coresight_etb_attrs[] = {
        &dev_attr_trigger_cntr.attr,
        NULL,
};

static const struct attribute_group coresight_etb_group = {
        .attrs = coresight_etb_attrs,
};

static const struct attribute_group coresight_etb_mgmt_group = {
        .attrs = coresight_etb_mgmt_attrs,
        .name = "mgmt",
};

static const struct attribute_group *coresight_etb_groups[] = {
        &coresight_etb_group,
        &coresight_etb_mgmt_group,
        NULL,
};

static int etb_probe(struct amba_device *adev, const struct amba_id *id)
{
        int ret;
        void __iomem *base;
        struct device *dev = &adev->dev;
        struct coresight_platform_data *pdata = NULL;
        struct etb_drvdata *drvdata;
        struct resource *res = &adev->res;
        struct coresight_desc desc = { 0 };

        desc.name = coresight_alloc_device_name(&etb_devs, dev);
        if (!desc.name)
                return -ENOMEM;

        drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
        if (!drvdata)
                return -ENOMEM;

        drvdata->atclk = devm_clk_get(&adev->dev, "atclk"); /* optional */
        if (!IS_ERR(drvdata->atclk)) {
                ret = clk_prepare_enable(drvdata->atclk);
                if (ret)
                        return ret;
        }
        dev_set_drvdata(dev, drvdata);

        /* validity for the resource is already checked by the AMBA core */
        base = devm_ioremap_resource(dev, res);
        if (IS_ERR(base))
                return PTR_ERR(base);

        drvdata->base = base;
        desc.access = CSDEV_ACCESS_IOMEM(base);

        spin_lock_init(&drvdata->spinlock);

        drvdata->buffer_depth = etb_get_buffer_depth(drvdata);

        if (drvdata->buffer_depth & 0x80000000)
                return -EINVAL;

        drvdata->buf = devm_kcalloc(dev,
                                    drvdata->buffer_depth, 4, GFP_KERNEL);
        if (!drvdata->buf)
                return -ENOMEM;

        /* This device is not associated with a session */
        drvdata->pid = -1;

        pdata = coresight_get_platform_data(dev);
        if (IS_ERR(pdata))
                return PTR_ERR(pdata);
        adev->dev.platform_data = pdata;

        desc.type = CORESIGHT_DEV_TYPE_SINK;
        desc.subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;
        desc.ops = &etb_cs_ops;
        desc.pdata = pdata;
        desc.dev = dev;
        desc.groups = coresight_etb_groups;
        drvdata->csdev = coresight_register(&desc);
        if (IS_ERR(drvdata->csdev))
                return PTR_ERR(drvdata->csdev);

        drvdata->miscdev.name = desc.name;
        drvdata->miscdev.minor = MISC_DYNAMIC_MINOR;
        drvdata->miscdev.fops = &etb_fops;
        ret = misc_register(&drvdata->miscdev);
        if (ret)
                goto err_misc_register;

        pm_runtime_put(&adev->dev);
        return 0;

err_misc_register:
        coresight_unregister(drvdata->csdev);
        return ret;
}

static void etb_remove(struct amba_device *adev)
{
        struct etb_drvdata *drvdata = dev_get_drvdata(&adev->dev);

        /*
         * Since misc_open() holds a refcount on the f_ops, which is
         * etb fops in this case, device is there until last file
         * handler to this device is closed.
         */
        misc_deregister(&drvdata->miscdev);
        coresight_unregister(drvdata->csdev);
}

#ifdef CONFIG_PM
static int etb_runtime_suspend(struct device *dev)
{
        struct etb_drvdata *drvdata = dev_get_drvdata(dev);

        if (drvdata && !IS_ERR(drvdata->atclk))
                clk_disable_unprepare(drvdata->atclk);

        return 0;
}

static int etb_runtime_resume(struct device *dev)
{
        struct etb_drvdata *drvdata = dev_get_drvdata(dev);

        if (drvdata && !IS_ERR(drvdata->atclk))
                clk_prepare_enable(drvdata->atclk);

        return 0;
}
#endif

static const struct dev_pm_ops etb_dev_pm_ops = {
        SET_RUNTIME_PM_OPS(etb_runtime_suspend, etb_runtime_resume, NULL)
};

static const struct amba_id etb_ids[] = {
        {
                .id     = 0x000bb907,
                .mask   = 0x000fffff,
        },
        { 0, 0, NULL },
};

MODULE_DEVICE_TABLE(amba, etb_ids);

static struct amba_driver etb_driver = {
        .drv = {
                .name   = "coresight-etb10",
                .pm     = &etb_dev_pm_ops,
                .suppress_bind_attrs = true,

        },
        .probe          = etb_probe,
        .remove         = etb_remove,
        .id_table       = etb_ids,
};

module_amba_driver(etb_driver);

MODULE_AUTHOR("Pratik Patel <pratikp@codeaurora.org>");
MODULE_AUTHOR("Mathieu Poirier <mathieu.poirier@linaro.org>");
MODULE_DESCRIPTION("Arm CoreSight Embedded Trace Buffer driver");
MODULE_LICENSE("GPL v2");