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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Intel(R) Trace Hub Memory Storage Unit
  *
  * Copyright (C) 2014-2015 Intel Corporation.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
 #include <linux/types.h>
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/uaccess.h>
 #include <linux/sizes.h>
 #include <linux/printk.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
 #include <linux/fs.h>
 #include <linux/io.h>
 #include <linux/workqueue.h>
 #include <linux/dma-mapping.h>
 
 #ifdef CONFIG_X86
 #include <asm/set_memory.h>
 #endif
 
 #include <linux/intel_th.h>
 #include "intel_th.h"
 #include "msu.h"
 
 #define msc_dev(x) (&(x)->thdev->dev)
 
 /*
  * Lockout state transitions:
  *   READY -> INUSE -+-> LOCKED -+-> READY -> etc.
  *                   \-----------/
  * WIN_READY:   window can be used by HW
  * WIN_INUSE:   window is in use
  * WIN_LOCKED:  window is filled up and is being processed by the buffer
  * handling code
  *
  * All state transitions happen automatically, except for the LOCKED->READY,
  * which needs to be signalled by the buffer code by calling
  * intel_th_msc_window_unlock().
  *
  * When the interrupt handler has to switch to the next window, it checks
  * whether it's READY, and if it is, it performs the switch and tracing
  * continues. If it's LOCKED, it stops the trace.
  */
 enum lockout_state {
     WIN_READY = 0,
     WIN_INUSE,
     WIN_LOCKED
 };
 
 /**
  * struct msc_window - multiblock mode window descriptor
  * @entry:  window list linkage (msc::win_list)
  * @pgoff:  page offset into the buffer that this window starts at
  * @lockout:    lockout state, see comment below
  * @lo_lock:    lockout state serialization
  * @nr_blocks:  number of blocks (pages) in this window
  * @nr_segs:    number of segments in this window (<= @nr_blocks)
  * @_sgt:   array of block descriptors
  * @sgt:    array of block descriptors
  */
 struct msc_window {
     struct list_head    entry;
     unsigned long       pgoff;
     enum lockout_state  lockout;
     spinlock_t      lo_lock;
     unsigned int        nr_blocks;
     unsigned int        nr_segs;
     struct msc      *msc;
     struct sg_table     _sgt;
     struct sg_table     *sgt;
 };
 
 /**
  * struct msc_iter - iterator for msc buffer
  * @entry:      msc::iter_list linkage
  * @msc:        pointer to the MSC device
  * @start_win:      oldest window
  * @win:        current window
  * @offset:     current logical offset into the buffer
  * @start_block:    oldest block in the window
  * @block:      block number in the window
  * @block_off:      offset into current block
  * @wrap_count:     block wrapping handling
  * @eof:        end of buffer reached
  */
 struct msc_iter {
     struct list_head    entry;
     struct msc      *msc;
     struct msc_window   *start_win;
     struct msc_window   *win;
     unsigned long       offset;
     struct scatterlist  *start_block;
     struct scatterlist  *block;
     unsigned int        block_off;
     unsigned int        wrap_count;
     unsigned int        eof;
 };
 
 /**
  * struct msc - MSC device representation
  * @reg_base:       register window base address
  * @thdev:      intel_th_device pointer
  * @mbuf:       MSU buffer, if assigned
  * @mbuf_priv       MSU buffer's private data, if @mbuf
  * @win_list:       list of windows in multiblock mode
  * @single_sgt:     single mode buffer
  * @cur_win:        current window
  * @nr_pages:       total number of pages allocated for this buffer
  * @single_sz:      amount of data in single mode
  * @single_wrap:    single mode wrap occurred
  * @base:       buffer's base pointer
  * @base_addr:      buffer's base address
  * @user_count:     number of users of the buffer
  * @mmap_count:     number of mappings
  * @buf_mutex:      mutex to serialize access to buffer-related bits
 
  * @enabled:        MSC is enabled
  * @wrap:       wrapping is enabled
  * @mode:       MSC operating mode
  * @burst_len:      write burst length
  * @index:      number of this MSC in the MSU
  */
 struct msc {
     void __iomem        *reg_base;
     void __iomem        *msu_base;
     struct intel_th_device  *thdev;
 
     const struct msu_buffer *mbuf;
     void            *mbuf_priv;
 
     struct work_struct  work;
     struct list_head    win_list;
     struct sg_table     single_sgt;
     struct msc_window   *cur_win;
     struct msc_window   *switch_on_unlock;
     unsigned long       nr_pages;
     unsigned long       single_sz;
     unsigned int        single_wrap : 1;
     void            *base;
     dma_addr_t      base_addr;
     u32         orig_addr;
     u32         orig_sz;
 
     /* <0: no buffer, 0: no users, >0: active users */
     atomic_t        user_count;
 
     atomic_t        mmap_count;
     struct mutex        buf_mutex;
 
     struct list_head    iter_list;
 
     bool            stop_on_full;
 
     /* config */
     unsigned int        enabled : 1,
                 wrap    : 1,
                 do_irq  : 1,
                 multi_is_broken : 1;
     unsigned int        mode;
     unsigned int        burst_len;
     unsigned int        index;
 };
 
 static LIST_HEAD(msu_buffer_list);
 static DEFINE_MUTEX(msu_buffer_mutex);
 
 /**
  * struct msu_buffer_entry - internal MSU buffer bookkeeping
  * @entry:  link to msu_buffer_list
  * @mbuf:   MSU buffer object
  * @owner:  module that provides this MSU buffer
  */
 struct msu_buffer_entry {
     struct list_head    entry;
     const struct msu_buffer *mbuf;
     struct module       *owner;
 };
 
 static struct msu_buffer_entry *__msu_buffer_entry_find(const char *name)
 {
     struct msu_buffer_entry *mbe;
 
     lockdep_assert_held(&msu_buffer_mutex);
 
     list_for_each_entry(mbe, &msu_buffer_list, entry) {
         if (!strcmp(mbe->mbuf->name, name))
             return mbe;
     }
 
     return NULL;
 }
 
 static const struct msu_buffer *
 msu_buffer_get(const char *name)
 {
     struct msu_buffer_entry *mbe;
 
     mutex_lock(&msu_buffer_mutex);
     mbe = __msu_buffer_entry_find(name);
     if (mbe && !try_module_get(mbe->owner))
         mbe = NULL;
     mutex_unlock(&msu_buffer_mutex);
 
     return mbe ? mbe->mbuf : NULL;
 }
 
 static void msu_buffer_put(const struct msu_buffer *mbuf)
 {
     struct msu_buffer_entry *mbe;
 
     mutex_lock(&msu_buffer_mutex);
     mbe = __msu_buffer_entry_find(mbuf->name);
     if (mbe)
         module_put(mbe->owner);
     mutex_unlock(&msu_buffer_mutex);
 }
 
 int intel_th_msu_buffer_register(const struct msu_buffer *mbuf,
                  struct module *owner)
 {
     struct msu_buffer_entry *mbe;
     int ret = 0;
 
     mbe = kzalloc(sizeof(*mbe), GFP_KERNEL);
     if (!mbe)
         return -ENOMEM;
 
     mutex_lock(&msu_buffer_mutex);
     if (__msu_buffer_entry_find(mbuf->name)) {
         ret = -EEXIST;
         kfree(mbe);
         goto unlock;
     }
 
     mbe->mbuf = mbuf;
     mbe->owner = owner;
     list_add_tail(&mbe->entry, &msu_buffer_list);
 unlock:
     mutex_unlock(&msu_buffer_mutex);
 
     return ret;
 }
 EXPORT_SYMBOL_GPL(intel_th_msu_buffer_register);
 
 void intel_th_msu_buffer_unregister(const struct msu_buffer *mbuf)
 {
     struct msu_buffer_entry *mbe;
 
     mutex_lock(&msu_buffer_mutex);
     mbe = __msu_buffer_entry_find(mbuf->name);
     if (mbe) {
         list_del(&mbe->entry);
         kfree(mbe);
     }
     mutex_unlock(&msu_buffer_mutex);
 }
 EXPORT_SYMBOL_GPL(intel_th_msu_buffer_unregister);
 
 static inline bool msc_block_is_empty(struct msc_block_desc *bdesc)
 {
     /* header hasn't been written */
     if (!bdesc->valid_dw)
         return true;
 
     /* valid_dw includes the header */
     if (!msc_data_sz(bdesc))
         return true;
 
     return false;
 }
 
 static inline struct scatterlist *msc_win_base_sg(struct msc_window *win)
 {
     return win->sgt->sgl;
 }
 
 static inline struct msc_block_desc *msc_win_base(struct msc_window *win)
 {
     return sg_virt(msc_win_base_sg(win));
 }
 
 static inline dma_addr_t msc_win_base_dma(struct msc_window *win)
 {
     return sg_dma_address(msc_win_base_sg(win));
 }
 
 static inline unsigned long
 msc_win_base_pfn(struct msc_window *win)
 {
     return PFN_DOWN(msc_win_base_dma(win));
 }
 
 /**
  * msc_is_last_win() - check if a window is the last one for a given MSC
  * @win:    window
  * Return:  true if @win is the last window in MSC's multiblock buffer
  */
 static inline bool msc_is_last_win(struct msc_window *win)
 {
     return win->entry.next == &win->msc->win_list;
 }
 
 /**
  * msc_next_window() - return next window in the multiblock buffer
  * @win:    current window
  *
  * Return:  window following the current one
  */
 static struct msc_window *msc_next_window(struct msc_window *win)
 {
     if (msc_is_last_win(win))
         return list_first_entry(&win->msc->win_list, struct msc_window,
                     entry);
 
     return list_next_entry(win, entry);
 }
 
 static size_t msc_win_total_sz(struct msc_window *win)
 {
     struct scatterlist *sg;
     unsigned int blk;
     size_t size = 0;
 
     for_each_sg(win->sgt->sgl, sg, win->nr_segs, blk) {
         struct msc_block_desc *bdesc = sg_virt(sg);
 
         if (msc_block_wrapped(bdesc))
             return (size_t)win->nr_blocks << PAGE_SHIFT;
 
         size += msc_total_sz(bdesc);
         if (msc_block_last_written(bdesc))
             break;
     }
 
     return size;
 }
 
 /**
  * msc_find_window() - find a window matching a given sg_table
  * @msc:    MSC device
  * @sgt:    SG table of the window
  * @nonempty:   skip over empty windows
  *
  * Return:  MSC window structure pointer or NULL if the window
  *      could not be found.
  */
 static struct msc_window *
 msc_find_window(struct msc *msc, struct sg_table *sgt, bool nonempty)
 {
     struct msc_window *win;
     unsigned int found = 0;
 
     if (list_empty(&msc->win_list))
         return NULL;
 
     /*
      * we might need a radix tree for this, depending on how
      * many windows a typical user would allocate; ideally it's
      * something like 2, in which case we're good
      */
     list_for_each_entry(win, &msc->win_list, entry) {
         if (win->sgt == sgt)
             found++;
 
         /* skip the empty ones */
         if (nonempty && msc_block_is_empty(msc_win_base(win)))
             continue;
 
         if (found)
             return win;
     }
 
     return NULL;
 }
 
 /**
  * msc_oldest_window() - locate the window with oldest data
  * @msc:    MSC device
  *
  * This should only be used in multiblock mode. Caller should hold the
  * msc::user_count reference.
  *
  * Return:  the oldest window with valid data
  */
 static struct msc_window *msc_oldest_window(struct msc *msc)
 {
     struct msc_window *win;
 
     if (list_empty(&msc->win_list))
         return NULL;
 
     win = msc_find_window(msc, msc_next_window(msc->cur_win)->sgt, true);
     if (win)
         return win;
 
     return list_first_entry(&msc->win_list, struct msc_window, entry);
 }
 
 /**
  * msc_win_oldest_sg() - locate the oldest block in a given window
  * @win:    window to look at
  *
  * Return:  index of the block with the oldest data
  */
 static struct scatterlist *msc_win_oldest_sg(struct msc_window *win)
 {
     unsigned int blk;
     struct scatterlist *sg;
     struct msc_block_desc *bdesc = msc_win_base(win);
 
     /* without wrapping, first block is the oldest */
     if (!msc_block_wrapped(bdesc))
         return msc_win_base_sg(win);
 
     /*
      * with wrapping, last written block contains both the newest and the
      * oldest data for this window.
      */
     for_each_sg(win->sgt->sgl, sg, win->nr_segs, blk) {
         struct msc_block_desc *bdesc = sg_virt(sg);
 
         if (msc_block_last_written(bdesc))
             return sg;
     }
 
     return msc_win_base_sg(win);
 }
 
 static struct msc_block_desc *msc_iter_bdesc(struct msc_iter *iter)
 {
     return sg_virt(iter->block);
 }
 
 static struct msc_iter *msc_iter_install(struct msc *msc)
 {
     struct msc_iter *iter;
 
     iter = kzalloc(sizeof(*iter), GFP_KERNEL);
     if (!iter)
         return ERR_PTR(-ENOMEM);
 
     mutex_lock(&msc->buf_mutex);
 
     /*
      * Reading and tracing are mutually exclusive; if msc is
      * enabled, open() will fail; otherwise existing readers
      * will prevent enabling the msc and the rest of fops don't
      * need to worry about it.
      */
     if (msc->enabled) {
         kfree(iter);
         iter = ERR_PTR(-EBUSY);
         goto unlock;
     }
 
     iter->msc = msc;
 
     list_add_tail(&iter->entry, &msc->iter_list);
 unlock:
     mutex_unlock(&msc->buf_mutex);
 
     return iter;
 }
 
 static void msc_iter_remove(struct msc_iter *iter, struct msc *msc)
 {
     mutex_lock(&msc->buf_mutex);
     list_del(&iter->entry);
     mutex_unlock(&msc->buf_mutex);
 
     kfree(iter);
 }
 
 static void msc_iter_block_start(struct msc_iter *iter)
 {
     if (iter->start_block)
         return;
 
     iter->start_block = msc_win_oldest_sg(iter->win);
     iter->block = iter->start_block;
     iter->wrap_count = 0;
 
     /*
      * start with the block with oldest data; if data has wrapped
      * in this window, it should be in this block
      */
     if (msc_block_wrapped(msc_iter_bdesc(iter)))
         iter->wrap_count = 2;
 
 }
 
 static int msc_iter_win_start(struct msc_iter *iter, struct msc *msc)
 {
     /* already started, nothing to do */
     if (iter->start_win)
         return 0;
 
     iter->start_win = msc_oldest_window(msc);
     if (!iter->start_win)
         return -EINVAL;
 
     iter->win = iter->start_win;
     iter->start_block = NULL;
 
     msc_iter_block_start(iter);
 
     return 0;
 }
 
 static int msc_iter_win_advance(struct msc_iter *iter)
 {
     iter->win = msc_next_window(iter->win);
     iter->start_block = NULL;
 
     if (iter->win == iter->start_win) {
         iter->eof++;
         return 1;
     }
 
     msc_iter_block_start(iter);
 
     return 0;
 }
 
 static int msc_iter_block_advance(struct msc_iter *iter)
 {
     iter->block_off = 0;
 
     /* wrapping */
     if (iter->wrap_count && iter->block == iter->start_block) {
         iter->wrap_count--;
         if (!iter->wrap_count)
             /* copied newest data from the wrapped block */
             return msc_iter_win_advance(iter);
     }
 
     /* no wrapping, check for last written block */
     if (!iter->wrap_count && msc_block_last_written(msc_iter_bdesc(iter)))
         /* copied newest data for the window */
         return msc_iter_win_advance(iter);
 
     /* block advance */
     if (sg_is_last(iter->block))
         iter->block = msc_win_base_sg(iter->win);
     else
         iter->block = sg_next(iter->block);
 
     /* no wrapping, sanity check in case there is no last written block */
     if (!iter->wrap_count && iter->block == iter->start_block)
         return msc_iter_win_advance(iter);
 
     return 0;
 }
 
 /**
  * msc_buffer_iterate() - go through multiblock buffer's data
  * @iter:   iterator structure
  * @size:   amount of data to scan
  * @data:   callback's private data
  * @fn:     iterator callback
  *
  * This will start at the window which will be written to next (containing
  * the oldest data) and work its way to the current window, calling @fn
  * for each chunk of data as it goes.
  *
  * Caller should have msc::user_count reference to make sure the buffer
  * doesn't disappear from under us.
  *
  * Return:  amount of data actually scanned.
  */
 static ssize_t
 msc_buffer_iterate(struct msc_iter *iter, size_t size, void *data,
            unsigned long (*fn)(void *, void *, size_t))
 {
     struct msc *msc = iter->msc;
     size_t len = size;
     unsigned int advance;
 
     if (iter->eof)
         return 0;
 
     /* start with the oldest window */
     if (msc_iter_win_start(iter, msc))
         return 0;
 
     do {
         unsigned long data_bytes = msc_data_sz(msc_iter_bdesc(iter));
         void *src = (void *)msc_iter_bdesc(iter) + MSC_BDESC;
         size_t tocopy = data_bytes, copied = 0;
         size_t remaining = 0;
 
         advance = 1;
 
         /*
          * If block wrapping happened, we need to visit the last block
          * twice, because it contains both the oldest and the newest
          * data in this window.
          *
          * First time (wrap_count==2), in the very beginning, to collect
          * the oldest data, which is in the range
          * (data_bytes..DATA_IN_PAGE).
          *
          * Second time (wrap_count==1), it's just like any other block,
          * containing data in the range of [MSC_BDESC..data_bytes].
          */
         if (iter->block == iter->start_block && iter->wrap_count == 2) {
             tocopy = DATA_IN_PAGE - data_bytes;
             src += data_bytes;
         }
 
         if (!tocopy)
             goto next_block;
 
         tocopy -= iter->block_off;
         src += iter->block_off;
 
         if (len < tocopy) {
             tocopy = len;
             advance = 0;
         }
 
         remaining = fn(data, src, tocopy);
 
         if (remaining)
             advance = 0;
 
         copied = tocopy - remaining;
         len -= copied;
         iter->block_off += copied;
         iter->offset += copied;
 
         if (!advance)
             break;
 
 next_block:
         if (msc_iter_block_advance(iter))
             break;
 
     } while (len);
 
     return size - len;
 }
 
 /**
  * msc_buffer_clear_hw_header() - clear hw header for multiblock
  * @msc:    MSC device
  */
 static void msc_buffer_clear_hw_header(struct msc *msc)
 {
     struct msc_window *win;
     struct scatterlist *sg;
 
     list_for_each_entry(win, &msc->win_list, entry) {
         unsigned int blk;
 
         for_each_sg(win->sgt->sgl, sg, win->nr_segs, blk) {
             struct msc_block_desc *bdesc = sg_virt(sg);
 
             memset_startat(bdesc, 0, hw_tag);
         }
     }
 }
 
 static int intel_th_msu_init(struct msc *msc)
 {
     u32 mintctl, msusts;
 
     if (!msc->do_irq)
         return 0;
 
     if (!msc->mbuf)
         return 0;
 
     mintctl = ioread32(msc->msu_base + REG_MSU_MINTCTL);
     mintctl |= msc->index ? M1BLIE : M0BLIE;
     iowrite32(mintctl, msc->msu_base + REG_MSU_MINTCTL);
     if (mintctl != ioread32(msc->msu_base + REG_MSU_MINTCTL)) {
         dev_info(msc_dev(msc), "MINTCTL ignores writes: no usable interrupts\n");
         msc->do_irq = 0;
         return 0;
     }
 
     msusts = ioread32(msc->msu_base + REG_MSU_MSUSTS);
     iowrite32(msusts, msc->msu_base + REG_MSU_MSUSTS);
 
     return 0;
 }
 
 static void intel_th_msu_deinit(struct msc *msc)
 {
     u32 mintctl;
 
     if (!msc->do_irq)
         return;
 
     mintctl = ioread32(msc->msu_base + REG_MSU_MINTCTL);
     mintctl &= msc->index ? ~M1BLIE : ~M0BLIE;
     iowrite32(mintctl, msc->msu_base + REG_MSU_MINTCTL);
 }
 
 static int msc_win_set_lockout(struct msc_window *win,
                    enum lockout_state expect,
                    enum lockout_state new)
 {
     enum lockout_state old;
     unsigned long flags;
     int ret = 0;
 
     if (!win->msc->mbuf)
         return 0;
 
     spin_lock_irqsave(&win->lo_lock, flags);
     old = win->lockout;
 
     if (old != expect) {
         ret = -EINVAL;
         goto unlock;
     }
 
     win->lockout = new;
 
     if (old == expect && new == WIN_LOCKED)
         atomic_inc(&win->msc->user_count);
     else if (old == expect && old == WIN_LOCKED)
         atomic_dec(&win->msc->user_count);
 
 unlock:
     spin_unlock_irqrestore(&win->lo_lock, flags);
 
     if (ret) {
         if (expect == WIN_READY && old == WIN_LOCKED)
             return -EBUSY;
 
         /* from intel_th_msc_window_unlock(), don't warn if not locked */
         if (expect == WIN_LOCKED && old == new)
             return 0;
 
         dev_warn_ratelimited(msc_dev(win->msc),
                      "expected lockout state %d, got %d\n",
                      expect, old);
     }
 
     return ret;
 }
 /**
  * msc_configure() - set up MSC hardware
  * @msc:    the MSC device to configure
  *
  * Program storage mode, wrapping, burst length and trace buffer address
  * into a given MSC. Then, enable tracing and set msc::enabled.
  * The latter is serialized on msc::buf_mutex, so make sure to hold it.
  */
 static int msc_configure(struct msc *msc)
 {
     u32 reg;
 
     lockdep_assert_held(&msc->buf_mutex);
 
     if (msc->mode > MSC_MODE_MULTI)
         return -EINVAL;
 
     if (msc->mode == MSC_MODE_MULTI) {
         if (msc_win_set_lockout(msc->cur_win, WIN_READY, WIN_INUSE))
             return -EBUSY;
 
         msc_buffer_clear_hw_header(msc);
     }
 
     msc->orig_addr = ioread32(msc->reg_base + REG_MSU_MSC0BAR);
     msc->orig_sz   = ioread32(msc->reg_base + REG_MSU_MSC0SIZE);
 
     reg = msc->base_addr >> PAGE_SHIFT;
     iowrite32(reg, msc->reg_base + REG_MSU_MSC0BAR);
 
     if (msc->mode == MSC_MODE_SINGLE) {
         reg = msc->nr_pages;
         iowrite32(reg, msc->reg_base + REG_MSU_MSC0SIZE);
     }
 
     reg = ioread32(msc->reg_base + REG_MSU_MSC0CTL);
     reg &= ~(MSC_MODE | MSC_WRAPEN | MSC_EN | MSC_RD_HDR_OVRD);
 
     reg |= MSC_EN;
     reg |= msc->mode << __ffs(MSC_MODE);
     reg |= msc->burst_len << __ffs(MSC_LEN);
 
     if (msc->wrap)
         reg |= MSC_WRAPEN;
 
     iowrite32(reg, msc->reg_base + REG_MSU_MSC0CTL);
 
     intel_th_msu_init(msc);
 
     msc->thdev->output.multiblock = msc->mode == MSC_MODE_MULTI;
     intel_th_trace_enable(msc->thdev);
     msc->enabled = 1;
 
     if (msc->mbuf && msc->mbuf->activate)
         msc->mbuf->activate(msc->mbuf_priv);
 
     return 0;
 }
 
 /**
  * msc_disable() - disable MSC hardware
  * @msc:    MSC device to disable
  *
  * If @msc is enabled, disable tracing on the switch and then disable MSC
  * storage. Caller must hold msc::buf_mutex.
  */
 static void msc_disable(struct msc *msc)
 {
     struct msc_window *win = msc->cur_win;
     u32 reg;
 
     lockdep_assert_held(&msc->buf_mutex);
 
     if (msc->mode == MSC_MODE_MULTI)
         msc_win_set_lockout(win, WIN_INUSE, WIN_LOCKED);
 
     if (msc->mbuf && msc->mbuf->deactivate)
         msc->mbuf->deactivate(msc->mbuf_priv);
     intel_th_msu_deinit(msc);
     intel_th_trace_disable(msc->thdev);
 
     if (msc->mode == MSC_MODE_SINGLE) {
         reg = ioread32(msc->reg_base + REG_MSU_MSC0STS);
         msc->single_wrap = !!(reg & MSCSTS_WRAPSTAT);
 
         reg = ioread32(msc->reg_base + REG_MSU_MSC0MWP);
         msc->single_sz = reg & ((msc->nr_pages << PAGE_SHIFT) - 1);
         dev_dbg(msc_dev(msc), "MSCnMWP: %08x/%08lx, wrap: %d\n",
             reg, msc->single_sz, msc->single_wrap);
     }
 
     reg = ioread32(msc->reg_base + REG_MSU_MSC0CTL);
     reg &= ~MSC_EN;
     iowrite32(reg, msc->reg_base + REG_MSU_MSC0CTL);
 
     if (msc->mbuf && msc->mbuf->ready)
         msc->mbuf->ready(msc->mbuf_priv, win->sgt,
                  msc_win_total_sz(win));
 
     msc->enabled = 0;
 
     iowrite32(msc->orig_addr, msc->reg_base + REG_MSU_MSC0BAR);
     iowrite32(msc->orig_sz, msc->reg_base + REG_MSU_MSC0SIZE);
 
     dev_dbg(msc_dev(msc), "MSCnNWSA: %08x\n",
         ioread32(msc->reg_base + REG_MSU_MSC0NWSA));
 
     reg = ioread32(msc->reg_base + REG_MSU_MSC0STS);
     dev_dbg(msc_dev(msc), "MSCnSTS: %08x\n", reg);
 
     reg = ioread32(msc->reg_base + REG_MSU_MSUSTS);
     reg &= msc->index ? MSUSTS_MSC1BLAST : MSUSTS_MSC0BLAST;
     iowrite32(reg, msc->reg_base + REG_MSU_MSUSTS);
 }
 
 static int intel_th_msc_activate(struct intel_th_device *thdev)
 {
     struct msc *msc = dev_get_drvdata(&thdev->dev);
     int ret = -EBUSY;
 
     if (!atomic_inc_unless_negative(&msc->user_count))
         return -ENODEV;
 
     mutex_lock(&msc->buf_mutex);
 
     /* if there are readers, refuse */
     if (list_empty(&msc->iter_list))
         ret = msc_configure(msc);
 
     mutex_unlock(&msc->buf_mutex);
 
     if (ret)
         atomic_dec(&msc->user_count);
 
     return ret;
 }
 
 static void intel_th_msc_deactivate(struct intel_th_device *thdev)
 {
     struct msc *msc = dev_get_drvdata(&thdev->dev);
 
     mutex_lock(&msc->buf_mutex);
     if (msc->enabled) {
         msc_disable(msc);
         atomic_dec(&msc->user_count);
     }
     mutex_unlock(&msc->buf_mutex);
 }
 
 /**
  * msc_buffer_contig_alloc() - allocate a contiguous buffer for SINGLE mode
  * @msc:    MSC device
  * @size:   allocation size in bytes
  *
  * This modifies msc::base, which requires msc::buf_mutex to serialize, so the
  * caller is expected to hold it.
  *
  * Return:  0 on success, -errno otherwise.
  */
 static int msc_buffer_contig_alloc(struct msc *msc, unsigned long size)
 {
     unsigned long nr_pages = size >> PAGE_SHIFT;
     unsigned int order = get_order(size);
     struct page *page;
     int ret;
 
     if (!size)
         return 0;
 
     ret = sg_alloc_table(&msc->single_sgt, 1, GFP_KERNEL);
     if (ret)
         goto err_out;
 
     ret = -ENOMEM;
     page = alloc_pages(GFP_KERNEL | __GFP_ZERO | GFP_DMA32, order);
     if (!page)
         goto err_free_sgt;
 
     split_page(page, order);
     sg_set_buf(msc->single_sgt.sgl, page_address(page), size);
 
     ret = dma_map_sg(msc_dev(msc)->parent->parent, msc->single_sgt.sgl, 1,
              DMA_FROM_DEVICE);
     if (ret < 0)
         goto err_free_pages;
 
     msc->nr_pages = nr_pages;
     msc->base = page_address(page);
     msc->base_addr = sg_dma_address(msc->single_sgt.sgl);
 
     return 0;
 
 err_free_pages:
     __free_pages(page, order);
 
 err_free_sgt:
     sg_free_table(&msc->single_sgt);
 
 err_out:
     return ret;
 }
 
 /**
  * msc_buffer_contig_free() - free a contiguous buffer
  * @msc:    MSC configured in SINGLE mode
  */
 static void msc_buffer_contig_free(struct msc *msc)
 {
     unsigned long off;
 
     dma_unmap_sg(msc_dev(msc)->parent->parent, msc->single_sgt.sgl,
              1, DMA_FROM_DEVICE);
     sg_free_table(&msc->single_sgt);
 
     for (off = 0; off < msc->nr_pages << PAGE_SHIFT; off += PAGE_SIZE) {
         struct page *page = virt_to_page(msc->base + off);
 
         page->mapping = NULL;
         __free_page(page);
     }
 
     msc->nr_pages = 0;
 }
 
 /**
  * msc_buffer_contig_get_page() - find a page at a given offset
  * @msc:    MSC configured in SINGLE mode
  * @pgoff:  page offset
  *
  * Return:  page, if @pgoff is within the range, NULL otherwise.
  */
 static struct page *msc_buffer_contig_get_page(struct msc *msc,
                            unsigned long pgoff)
 {
     if (pgoff >= msc->nr_pages)
         return NULL;
 
     return virt_to_page(msc->base + (pgoff << PAGE_SHIFT));
 }
 
 static int __msc_buffer_win_alloc(struct msc_window *win,
                   unsigned int nr_segs)
 {
     struct scatterlist *sg_ptr;
     void *block;
     int i, ret;
 
     ret = sg_alloc_table(win->sgt, nr_segs, GFP_KERNEL);
     if (ret)
         return -ENOMEM;
 
     for_each_sg(win->sgt->sgl, sg_ptr, nr_segs, i) {
         block = dma_alloc_coherent(msc_dev(win->msc)->parent->parent,
                       PAGE_SIZE, &sg_dma_address(sg_ptr),
                       GFP_KERNEL);
         if (!block)
             goto err_nomem;
 
         sg_set_buf(sg_ptr, block, PAGE_SIZE);
     }
 
     return nr_segs;
 
 err_nomem:
     for_each_sg(win->sgt->sgl, sg_ptr, i, ret)
         dma_free_coherent(msc_dev(win->msc)->parent->parent, PAGE_SIZE,
                   sg_virt(sg_ptr), sg_dma_address(sg_ptr));
 
     sg_free_table(win->sgt);
 
     return -ENOMEM;
 }
 
 #ifdef CONFIG_X86
 static void msc_buffer_set_uc(struct msc *msc)
 {
     struct scatterlist *sg_ptr;
     struct msc_window *win;
     int i;
 
     if (msc->mode == MSC_MODE_SINGLE) {
         set_memory_uc((unsigned long)msc->base, msc->nr_pages);
         return;
     }
 
     list_for_each_entry(win, &msc->win_list, entry) {
         for_each_sg(win->sgt->sgl, sg_ptr, win->nr_segs, i) {
             /* Set the page as uncached */
             set_memory_uc((unsigned long)sg_virt(sg_ptr),
                     PFN_DOWN(sg_ptr->length));
         }
     }
 }
 
 static void msc_buffer_set_wb(struct msc *msc)
 {
     struct scatterlist *sg_ptr;
     struct msc_window *win;
     int i;
 
     if (msc->mode == MSC_MODE_SINGLE) {
         set_memory_wb((unsigned long)msc->base, msc->nr_pages);
         return;
     }
 
     list_for_each_entry(win, &msc->win_list, entry) {
         for_each_sg(win->sgt->sgl, sg_ptr, win->nr_segs, i) {
             /* Reset the page to write-back */
             set_memory_wb((unsigned long)sg_virt(sg_ptr),
                     PFN_DOWN(sg_ptr->length));
         }
     }
 }
 #else /* !X86 */
 static inline void
 msc_buffer_set_uc(struct msc *msc) {}
 static inline void msc_buffer_set_wb(struct msc *msc) {}
 #endif /* CONFIG_X86 */
 
 static struct page *msc_sg_page(struct scatterlist *sg)
 {
     void *addr = sg_virt(sg);
 
     if (is_vmalloc_addr(addr))
         return vmalloc_to_page(addr);
 
     return sg_page(sg);
 }
 
 /**
  * msc_buffer_win_alloc() - alloc a window for a multiblock mode
  * @msc:    MSC device
  * @nr_blocks:  number of pages in this window
  *
  * This modifies msc::win_list and msc::base, which requires msc::buf_mutex
  * to serialize, so the caller is expected to hold it.
  *
  * Return:  0 on success, -errno otherwise.
  */
 static int msc_buffer_win_alloc(struct msc *msc, unsigned int nr_blocks)
 {
     struct msc_window *win;
     int ret = -ENOMEM;
 
     if (!nr_blocks)
         return 0;
 
     win = kzalloc(sizeof(*win), GFP_KERNEL);
     if (!win)
         return -ENOMEM;
 
     win->msc = msc;
     win->sgt = &win->_sgt;
     win->lockout = WIN_READY;
     spin_lock_init(&win->lo_lock);
 
     if (!list_empty(&msc->win_list)) {
         struct msc_window *prev = list_last_entry(&msc->win_list,
                               struct msc_window,
                               entry);
 
         win->pgoff = prev->pgoff + prev->nr_blocks;
     }
 
     if (msc->mbuf && msc->mbuf->alloc_window)
         ret = msc->mbuf->alloc_window(msc->mbuf_priv, &win->sgt,
                           nr_blocks << PAGE_SHIFT);
     else
         ret = __msc_buffer_win_alloc(win, nr_blocks);
 
     if (ret <= 0)
         goto err_nomem;
 
     win->nr_segs = ret;
     win->nr_blocks = nr_blocks;
 
     if (list_empty(&msc->win_list)) {
         msc->base = msc_win_base(win);
         msc->base_addr = msc_win_base_dma(win);
         msc->cur_win = win;
     }
 
     list_add_tail(&win->entry, &msc->win_list);
     msc->nr_pages += nr_blocks;
 
     return 0;
 
 err_nomem:
     kfree(win);
 
     return ret;
 }
 
 static void __msc_buffer_win_free(struct msc *msc, struct msc_window *win)
 {
     struct scatterlist *sg;
     int i;
 
     for_each_sg(win->sgt->sgl, sg, win->nr_segs, i) {
         struct page *page = msc_sg_page(sg);
 
         page->mapping = NULL;
         dma_free_coherent(msc_dev(win->msc)->parent->parent, PAGE_SIZE,
                   sg_virt(sg), sg_dma_address(sg));
     }
     sg_free_table(win->sgt);
 }
 
 /**
  * msc_buffer_win_free() - free a window from MSC's window list
  * @msc:    MSC device
  * @win:    window to free
  *
  * This modifies msc::win_list and msc::base, which requires msc::buf_mutex
  * to serialize, so the caller is expected to hold it.
  */
 static void msc_buffer_win_free(struct msc *msc, struct msc_window *win)
 {
     msc->nr_pages -= win->nr_blocks;
 
     list_del(&win->entry);
     if (list_empty(&msc->win_list)) {
         msc->base = NULL;
         msc->base_addr = 0;
     }
 
     if (msc->mbuf && msc->mbuf->free_window)
         msc->mbuf->free_window(msc->mbuf_priv, win->sgt);
     else
         __msc_buffer_win_free(msc, win);
 
     kfree(win);
 }
 
 /**
  * msc_buffer_relink() - set up block descriptors for multiblock mode
  * @msc:    MSC device
  *
  * This traverses msc::win_list, which requires msc::buf_mutex to serialize,
  * so the caller is expected to hold it.
  */
 static void msc_buffer_relink(struct msc *msc)
 {
     struct msc_window *win, *next_win;
 
     /* call with msc::mutex locked */
     list_for_each_entry(win, &msc->win_list, entry) {
         struct scatterlist *sg;
         unsigned int blk;
         u32 sw_tag = 0;
 
         /*
          * Last window's next_win should point to the first window
          * and MSC_SW_TAG_LASTWIN should be set.
          */
         if (msc_is_last_win(win)) {
             sw_tag |= MSC_SW_TAG_LASTWIN;
             next_win = list_first_entry(&msc->win_list,
                             struct msc_window, entry);
         } else {
             next_win = list_next_entry(win, entry);
         }
 
         for_each_sg(win->sgt->sgl, sg, win->nr_segs, blk) {
             struct msc_block_desc *bdesc = sg_virt(sg);
 
             memset(bdesc, 0, sizeof(*bdesc));
 
             bdesc->next_win = msc_win_base_pfn(next_win);
 
             /*
              * Similarly to last window, last block should point
              * to the first one.
              */
             if (blk == win->nr_segs - 1) {
                 sw_tag |= MSC_SW_TAG_LASTBLK;
                 bdesc->next_blk = msc_win_base_pfn(win);
             } else {
                 dma_addr_t addr = sg_dma_address(sg_next(sg));
 
                 bdesc->next_blk = PFN_DOWN(addr);
             }
 
             bdesc->sw_tag = sw_tag;
             bdesc->block_sz = sg->length / 64;
         }
     }
 
     /*
      * Make the above writes globally visible before tracing is
      * enabled to make sure hardware sees them coherently.
      */
     wmb();
 }
 
 static void msc_buffer_multi_free(struct msc *msc)
 {
     struct msc_window *win, *iter;
 
     list_for_each_entry_safe(win, iter, &msc->win_list, entry)
         msc_buffer_win_free(msc, win);
 }
 
 static int msc_buffer_multi_alloc(struct msc *msc, unsigned long *nr_pages,
                   unsigned int nr_wins)
 {
     int ret, i;
 
     for (i = 0; i < nr_wins; i++) {
         ret = msc_buffer_win_alloc(msc, nr_pages[i]);
         if (ret) {
             msc_buffer_multi_free(msc);
             return ret;
         }
     }
 
     msc_buffer_relink(msc);
 
     return 0;
 }
 
 /**
  * msc_buffer_free() - free buffers for MSC
  * @msc:    MSC device
  *
  * Free MSC's storage buffers.
  *
  * This modifies msc::win_list and msc::base, which requires msc::buf_mutex to
  * serialize, so the caller is expected to hold it.
  */
 static void msc_buffer_free(struct msc *msc)
 {
     msc_buffer_set_wb(msc);
 
     if (msc->mode == MSC_MODE_SINGLE)
         msc_buffer_contig_free(msc);
     else if (msc->mode == MSC_MODE_MULTI)
         msc_buffer_multi_free(msc);
 }
 
 /**
  * msc_buffer_alloc() - allocate a buffer for MSC
  * @msc:    MSC device
  * @size:   allocation size in bytes
  *
  * Allocate a storage buffer for MSC, depending on the msc::mode, it will be
  * either done via msc_buffer_contig_alloc() for SINGLE operation mode or
  * msc_buffer_win_alloc() for multiblock operation. The latter allocates one
  * window per invocation, so in multiblock mode this can be called multiple
  * times for the same MSC to allocate multiple windows.
  *
  * This modifies msc::win_list and msc::base, which requires msc::buf_mutex
  * to serialize, so the caller is expected to hold it.
  *
  * Return:  0 on success, -errno otherwise.
  */
 static int msc_buffer_alloc(struct msc *msc, unsigned long *nr_pages,
                 unsigned int nr_wins)
 {
     int ret;
 
     /* -1: buffer not allocated */
     if (atomic_read(&msc->user_count) != -1)
         return -EBUSY;
 
     if (msc->mode == MSC_MODE_SINGLE) {
         if (nr_wins != 1)
             return -EINVAL;
 
         ret = msc_buffer_contig_alloc(msc, nr_pages[0] << PAGE_SHIFT);
     } else if (msc->mode == MSC_MODE_MULTI) {
         ret = msc_buffer_multi_alloc(msc, nr_pages, nr_wins);
     } else {
         ret = -EINVAL;
     }
 
     if (!ret) {
         msc_buffer_set_uc(msc);
 
         /* allocation should be visible before the counter goes to 0 */
         smp_mb__before_atomic();
 
         if (WARN_ON_ONCE(atomic_cmpxchg(&msc->user_count, -1, 0) != -1))
             return -EINVAL;
     }
 
     return ret;
 }
 
 /**
  * msc_buffer_unlocked_free_unless_used() - free a buffer unless it's in use
  * @msc:    MSC device
  *
  * This will free MSC buffer unless it is in use or there is no allocated
  * buffer.
  * Caller needs to hold msc::buf_mutex.
  *
  * Return:  0 on successful deallocation or if there was no buffer to
  *      deallocate, -EBUSY if there are active users.
  */
 static int msc_buffer_unlocked_free_unless_used(struct msc *msc)
 {
     int count, ret = 0;
 
     count = atomic_cmpxchg(&msc->user_count, 0, -1);
 
     /* > 0: buffer is allocated and has users */
     if (count > 0)
         ret = -EBUSY;
     /* 0: buffer is allocated, no users */
     else if (!count)
         msc_buffer_free(msc);
     /* < 0: no buffer, nothing to do */
 
     return ret;
 }
 
 /**
  * msc_buffer_free_unless_used() - free a buffer unless it's in use
  * @msc:    MSC device
  *
  * This is a locked version of msc_buffer_unlocked_free_unless_used().
  */
 static int msc_buffer_free_unless_used(struct msc *msc)
 {
     int ret;
 
     mutex_lock(&msc->buf_mutex);
     ret = msc_buffer_unlocked_free_unless_used(msc);
     mutex_unlock(&msc->buf_mutex);
 
     return ret;
 }
 
 /**
  * msc_buffer_get_page() - get MSC buffer page at a given offset
  * @msc:    MSC device
  * @pgoff:  page offset into the storage buffer
  *
  * This traverses msc::win_list, so holding msc::buf_mutex is expected from
  * the caller.
  *
  * Return:  page if @pgoff corresponds to a valid buffer page or NULL.
  */
 static struct page *msc_buffer_get_page(struct msc *msc, unsigned long pgoff)
 {
     struct msc_window *win;
     struct scatterlist *sg;
     unsigned int blk;
 
     if (msc->mode == MSC_MODE_SINGLE)
         return msc_buffer_contig_get_page(msc, pgoff);
 
     list_for_each_entry(win, &msc->win_list, entry)
         if (pgoff >= win->pgoff && pgoff < win->pgoff + win->nr_blocks)
             goto found;
 
     return NULL;
 
 found:
     pgoff -= win->pgoff;
 
     for_each_sg(win->sgt->sgl, sg, win->nr_segs, blk) {
         struct page *page = msc_sg_page(sg);
         size_t pgsz = PFN_DOWN(sg->length);
 
         if (pgoff < pgsz)
             return page + pgoff;
 
         pgoff -= pgsz;
     }
 
     return NULL;
 }
 
 /**
  * struct msc_win_to_user_struct - data for copy_to_user() callback
  * @buf:    userspace buffer to copy data to
  * @offset: running offset
  */
 struct msc_win_to_user_struct {
     char __user *buf;
     unsigned long   offset;
 };
 
 /**
  * msc_win_to_user() - iterator for msc_buffer_iterate() to copy data to user
  * @data:   callback's private data
  * @src:    source buffer
  * @len:    amount of data to copy from the source buffer
  */
 static unsigned long msc_win_to_user(void *data, void *src, size_t len)
 {
     struct msc_win_to_user_struct *u = data;
     unsigned long ret;
 
     ret = copy_to_user(u->buf + u->offset, src, len);
     u->offset += len - ret;
 
     return ret;
 }
 
 
 /*
  * file operations' callbacks
  */
 
 static int intel_th_msc_open(struct inode *inode, struct file *file)
 {
     struct intel_th_device *thdev = file->private_data;
     struct msc *msc = dev_get_drvdata(&thdev->dev);
     struct msc_iter *iter;
 
     if (!capable(CAP_SYS_RAWIO))
         return -EPERM;
 
     iter = msc_iter_install(msc);
     if (IS_ERR(iter))
         return PTR_ERR(iter);
 
     file->private_data = iter;
 
     return nonseekable_open(inode, file);
 }
 
 static int intel_th_msc_release(struct inode *inode, struct file *file)
 {
     struct msc_iter *iter = file->private_data;
     struct msc *msc = iter->msc;
 
     msc_iter_remove(iter, msc);
 
     return 0;
 }
 
 static ssize_t
 msc_single_to_user(struct msc *msc, char __user *buf, loff_t off, size_t len)
 {
     unsigned long size = msc->nr_pages << PAGE_SHIFT, rem = len;
     unsigned long start = off, tocopy = 0;
 
     if (msc->single_wrap) {
         start += msc->single_sz;
         if (start < size) {
             tocopy = min(rem, size - start);
             if (copy_to_user(buf, msc->base + start, tocopy))
                 return -EFAULT;
 
             buf += tocopy;
             rem -= tocopy;
             start += tocopy;
         }
 
         start &= size - 1;
         if (rem) {
             tocopy = min(rem, msc->single_sz - start);
             if (copy_to_user(buf, msc->base + start, tocopy))
                 return -EFAULT;
 
             rem -= tocopy;
         }
 
         return len - rem;
     }
 
     if (copy_to_user(buf, msc->base + start, rem))
         return -EFAULT;
 
     return len;
 }
 
 static ssize_t intel_th_msc_read(struct file *file, char __user *buf,
                  size_t len, loff_t *ppos)
 {
     struct msc_iter *iter = file->private_data;
     struct msc *msc = iter->msc;
     size_t size;
     loff_t off = *ppos;
     ssize_t ret = 0;
 
     if (!atomic_inc_unless_negative(&msc->user_count))
         return 0;
 
     if (msc->mode == MSC_MODE_SINGLE && !msc->single_wrap)
         size = msc->single_sz;
     else
         size = msc->nr_pages << PAGE_SHIFT;
 
     if (!size)
         goto put_count;
 
     if (off >= size)
         goto put_count;
 
     if (off + len >= size)
         len = size - off;
 
     if (msc->mode == MSC_MODE_SINGLE) {
         ret = msc_single_to_user(msc, buf, off, len);
         if (ret >= 0)
             *ppos += ret;
     } else if (msc->mode == MSC_MODE_MULTI) {
         struct msc_win_to_user_struct u = {
             .buf    = buf,
             .offset = 0,
         };
 
         ret = msc_buffer_iterate(iter, len, &u, msc_win_to_user);
         if (ret >= 0)
             *ppos = iter->offset;
     } else {
         ret = -EINVAL;
     }
 
 put_count:
     atomic_dec(&msc->user_count);
 
     return ret;
 }
 
 /*
  * vm operations callbacks (vm_ops)
  */
 
 static void msc_mmap_open(struct vm_area_struct *vma)
 {
     struct msc_iter *iter = vma->vm_file->private_data;
     struct msc *msc = iter->msc;
 
     atomic_inc(&msc->mmap_count);
 }
 
 static void msc_mmap_close(struct vm_area_struct *vma)
 {
     struct msc_iter *iter = vma->vm_file->private_data;
     struct msc *msc = iter->msc;
     unsigned long pg;
 
     if (!atomic_dec_and_mutex_lock(&msc->mmap_count, &msc->buf_mutex))
         return;
 
     /* drop page _refcounts */
     for (pg = 0; pg < msc->nr_pages; pg++) {
         struct page *page = msc_buffer_get_page(msc, pg);
 
         if (WARN_ON_ONCE(!page))
             continue;
 
         if (page->mapping)
             page->mapping = NULL;
     }
 
     /* last mapping -- drop user_count */
     atomic_dec(&msc->user_count);
     mutex_unlock(&msc->buf_mutex);
 }
 
 static vm_fault_t msc_mmap_fault(struct vm_fault *vmf)
 {
     struct msc_iter *iter = vmf->vma->vm_file->private_data;
     struct msc *msc = iter->msc;
 
     vmf->page = msc_buffer_get_page(msc, vmf->pgoff);
     if (!vmf->page)
         return VM_FAULT_SIGBUS;
 
     get_page(vmf->page);
     vmf->page->mapping = vmf->vma->vm_file->f_mapping;
     vmf->page->index = vmf->pgoff;
 
     return 0;
 }
 
 static const struct vm_operations_struct msc_mmap_ops = {
     .open   = msc_mmap_open,
     .close  = msc_mmap_close,
     .fault  = msc_mmap_fault,
 };
 
 static int intel_th_msc_mmap(struct file *file, struct vm_area_struct *vma)
 {
     unsigned long size = vma->vm_end - vma->vm_start;
     struct msc_iter *iter = vma->vm_file->private_data;
     struct msc *msc = iter->msc;
     int ret = -EINVAL;
 
     if (!size || offset_in_page(size))
         return -EINVAL;
 
     if (vma->vm_pgoff)
         return -EINVAL;
 
     /* grab user_count once per mmap; drop in msc_mmap_close() */
     if (!atomic_inc_unless_negative(&msc->user_count))
         return -EINVAL;
 
     if (msc->mode != MSC_MODE_SINGLE &&
         msc->mode != MSC_MODE_MULTI)
         goto out;
 
     if (size >> PAGE_SHIFT != msc->nr_pages)
         goto out;
 
     atomic_set(&msc->mmap_count, 1);
     ret = 0;
 
 out:
     if (ret)
         atomic_dec(&msc->user_count);
 
     vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
     vma->vm_flags |= VM_DONTEXPAND | VM_DONTCOPY;
     vma->vm_ops = &msc_mmap_ops;
     return ret;
 }
 
 static const struct file_operations intel_th_msc_fops = {
     .open       = intel_th_msc_open,
     .release    = intel_th_msc_release,
     .read       = intel_th_msc_read,
     .mmap       = intel_th_msc_mmap,
     .llseek     = no_llseek,
     .owner      = THIS_MODULE,
 };
 
 static void intel_th_msc_wait_empty(struct intel_th_device *thdev)
 {
     struct msc *msc = dev_get_drvdata(&thdev->dev);
     unsigned long count;
     u32 reg;
 
     for (reg = 0, count = MSC_PLE_WAITLOOP_DEPTH;
          count && !(reg & MSCSTS_PLE); count--) {
         reg = __raw_readl(msc->reg_base + REG_MSU_MSC0STS);
         cpu_relax();
     }
 
     if (!count)
         dev_dbg(msc_dev(msc), "timeout waiting for MSC0 PLE\n");
 }
 
 static int intel_th_msc_init(struct msc *msc)
 {
     atomic_set(&msc->user_count, -1);
 
     msc->mode = msc->multi_is_broken ? MSC_MODE_SINGLE : MSC_MODE_MULTI;
     mutex_init(&msc->buf_mutex);
     INIT_LIST_HEAD(&msc->win_list);
     INIT_LIST_HEAD(&msc->iter_list);
 
     msc->burst_len =
         (ioread32(msc->reg_base + REG_MSU_MSC0CTL) & MSC_LEN) >>
         __ffs(MSC_LEN);
 
     return 0;
 }
 
 static int msc_win_switch(struct msc *msc)
 {
     struct msc_window *first;
 
     if (list_empty(&msc->win_list))
         return -EINVAL;
 
     first = list_first_entry(&msc->win_list, struct msc_window, entry);
 
     if (msc_is_last_win(msc->cur_win))
         msc->cur_win = first;
     else
         msc->cur_win = list_next_entry(msc->cur_win, entry);
 
     msc->base = msc_win_base(msc->cur_win);
     msc->base_addr = msc_win_base_dma(msc->cur_win);
 
     intel_th_trace_switch(msc->thdev);
 
     return 0;
 }
 
 /**
  * intel_th_msc_window_unlock - put the window back in rotation
  * @dev:    MSC device to which this relates
  * @sgt:    buffer's sg_table for the window, does nothing if NULL
  */
 void intel_th_msc_window_unlock(struct device *dev, struct sg_table *sgt)
 {
     struct msc *msc = dev_get_drvdata(dev);
     struct msc_window *win;
 
     if (!sgt)
         return;
 
     win = msc_find_window(msc, sgt, false);
     if (!win)
         return;
 
     msc_win_set_lockout(win, WIN_LOCKED, WIN_READY);
     if (msc->switch_on_unlock == win) {
         msc->switch_on_unlock = NULL;
         msc_win_switch(msc);
     }
 }
 EXPORT_SYMBOL_GPL(intel_th_msc_window_unlock);
 
 static void msc_work(struct work_struct *work)
 {
     struct msc *msc = container_of(work, struct msc, work);
 
     intel_th_msc_deactivate(msc->thdev);
 }
 
 static irqreturn_t intel_th_msc_interrupt(struct intel_th_device *thdev)
 {
     struct msc *msc = dev_get_drvdata(&thdev->dev);
     u32 msusts = ioread32(msc->msu_base + REG_MSU_MSUSTS);
     u32 mask = msc->index ? MSUSTS_MSC1BLAST : MSUSTS_MSC0BLAST;
     struct msc_window *win, *next_win;
 
     if (!msc->do_irq || !msc->mbuf)
         return IRQ_NONE;
 
     msusts &= mask;
 
     if (!msusts)
         return msc->enabled ? IRQ_HANDLED : IRQ_NONE;
 
     iowrite32(msusts, msc->msu_base + REG_MSU_MSUSTS);
 
     if (!msc->enabled)
         return IRQ_NONE;
 
     /* grab the window before we do the switch */
     win = msc->cur_win;
     if (!win)
         return IRQ_HANDLED;
     next_win = msc_next_window(win);
     if (!next_win)
         return IRQ_HANDLED;
 
     /* next window: if READY, proceed, if LOCKED, stop the trace */
     if (msc_win_set_lockout(next_win, WIN_READY, WIN_INUSE)) {
         if (msc->stop_on_full)
             schedule_work(&msc->work);
         else
             msc->switch_on_unlock = next_win;
 
         return IRQ_HANDLED;
     }
 
     /* current window: INUSE -> LOCKED */
     msc_win_set_lockout(win, WIN_INUSE, WIN_LOCKED);
 
     msc_win_switch(msc);
 
     if (msc->mbuf && msc->mbuf->ready)
         msc->mbuf->ready(msc->mbuf_priv, win->sgt,
                  msc_win_total_sz(win));
 
     return IRQ_HANDLED;
 }
 
 static const char * const msc_mode[] = {
     [MSC_MODE_SINGLE]   = "single",
     [MSC_MODE_MULTI]    = "multi",
     [MSC_MODE_EXI]      = "ExI",
     [MSC_MODE_DEBUG]    = "debug",
 };
 
 static ssize_t
 wrap_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
     struct msc *msc = dev_get_drvdata(dev);
 
     return scnprintf(buf, PAGE_SIZE, "%d\n", msc->wrap);
 }
 
 static ssize_t
 wrap_store(struct device *dev, struct device_attribute *attr, const char *buf,
        size_t size)
 {
     struct msc *msc = dev_get_drvdata(dev);
     unsigned long val;
     int ret;
 
     ret = kstrtoul(buf, 10, &val);
     if (ret)
         return ret;
 
     msc->wrap = !!val;
 
     return size;
 }
 
 static DEVICE_ATTR_RW(wrap);
 
 static void msc_buffer_unassign(struct msc *msc)
 {
     lockdep_assert_held(&msc->buf_mutex);
 
     if (!msc->mbuf)
         return;
 
     msc->mbuf->unassign(msc->mbuf_priv);
     msu_buffer_put(msc->mbuf);
     msc->mbuf_priv = NULL;
     msc->mbuf = NULL;
 }
 
 static ssize_t
 mode_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
     struct msc *msc = dev_get_drvdata(dev);
     const char *mode = msc_mode[msc->mode];
     ssize_t ret;
 
     mutex_lock(&msc->buf_mutex);
     if (msc->mbuf)
         mode = msc->mbuf->name;
     ret = scnprintf(buf, PAGE_SIZE, "%s\n", mode);
     mutex_unlock(&msc->buf_mutex);
 
     return ret;
 }
 
 static ssize_t
 mode_store(struct device *dev, struct device_attribute *attr, const char *buf,
        size_t size)
 {
     const struct msu_buffer *mbuf = NULL;
     struct msc *msc = dev_get_drvdata(dev);
     size_t len = size;
     char *cp, *mode;
     int i, ret;
 
     if (!capable(CAP_SYS_RAWIO))
         return -EPERM;
 
     cp = memchr(buf, '\n', len);
     if (cp)
         len = cp - buf;
 
     mode = kstrndup(buf, len, GFP_KERNEL);
     if (!mode)
         return -ENOMEM;
 
     i = match_string(msc_mode, ARRAY_SIZE(msc_mode), mode);
     if (i >= 0) {
         kfree(mode);
         goto found;
     }
 
     /* Buffer sinks only work with a usable IRQ */
     if (!msc->do_irq) {
         kfree(mode);
         return -EINVAL;
     }
 
     mbuf = msu_buffer_get(mode);
     kfree(mode);
     if (mbuf)
         goto found;
 
     return -EINVAL;
 
 found:
     if (i == MSC_MODE_MULTI && msc->multi_is_broken)
         return -EOPNOTSUPP;
 
     mutex_lock(&msc->buf_mutex);
     ret = 0;
 
     /* Same buffer: do nothing */
     if (mbuf && mbuf == msc->mbuf) {
         /* put the extra reference we just got */
         msu_buffer_put(mbuf);
         goto unlock;
     }
 
     ret = msc_buffer_unlocked_free_unless_used(msc);
     if (ret)
         goto unlock;
 
     if (mbuf) {
         void *mbuf_priv = mbuf->assign(dev, &i);
 
         if (!mbuf_priv) {
             ret = -ENOMEM;
             goto unlock;
         }
 
         msc_buffer_unassign(msc);
         msc->mbuf_priv = mbuf_priv;
         msc->mbuf = mbuf;
     } else {
         msc_buffer_unassign(msc);
     }
 
     msc->mode = i;
 
 unlock:
     if (ret && mbuf)
         msu_buffer_put(mbuf);
     mutex_unlock(&msc->buf_mutex);
 
     return ret ? ret : size;
 }
 
 static DEVICE_ATTR_RW(mode);
 
 static ssize_t
 nr_pages_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
     struct msc *msc = dev_get_drvdata(dev);
     struct msc_window *win;
     size_t count = 0;
 
     mutex_lock(&msc->buf_mutex);
 
     if (msc->mode == MSC_MODE_SINGLE)
         count = scnprintf(buf, PAGE_SIZE, "%ld\n", msc->nr_pages);
     else if (msc->mode == MSC_MODE_MULTI) {
         list_for_each_entry(win, &msc->win_list, entry) {
             count += scnprintf(buf + count, PAGE_SIZE - count,
                        "%d%c", win->nr_blocks,
                        msc_is_last_win(win) ? '\n' : ',');
         }
     } else {
         count = scnprintf(buf, PAGE_SIZE, "unsupported\n");
     }
 
     mutex_unlock(&msc->buf_mutex);
 
     return count;
 }
 
 static ssize_t
 nr_pages_store(struct device *dev, struct device_attribute *attr,
            const char *buf, size_t size)
 {
     struct msc *msc = dev_get_drvdata(dev);
     unsigned long val, *win = NULL, *rewin;
     size_t len = size;
     const char *p = buf;
     char *end, *s;
     int ret, nr_wins = 0;
 
     if (!capable(CAP_SYS_RAWIO))
         return -EPERM;
 
     ret = msc_buffer_free_unless_used(msc);
     if (ret)
         return ret;
 
     /* scan the comma-separated list of allocation sizes */
     end = memchr(buf, '\n', len);
     if (end)
         len = end - buf;
 
     do {
         end = memchr(p, ',', len);
         s = kstrndup(p, end ? end - p : len, GFP_KERNEL);
         if (!s) {
             ret = -ENOMEM;
             goto free_win;
         }
 
         ret = kstrtoul(s, 10, &val);
         kfree(s);
 
         if (ret || !val)
             goto free_win;
 
         if (nr_wins && msc->mode == MSC_MODE_SINGLE) {
             ret = -EINVAL;
             goto free_win;
         }
 
         nr_wins++;
         rewin = krealloc_array(win, nr_wins, sizeof(*win), GFP_KERNEL);
         if (!rewin) {
             kfree(win);
             return -ENOMEM;
         }
 
         win = rewin;
         win[nr_wins - 1] = val;
 
         if (!end)
             break;
 
         /* consume the number and the following comma, hence +1 */
         len -= end - p + 1;
         p = end + 1;
     } while (len);
 
     mutex_lock(&msc->buf_mutex);
     ret = msc_buffer_alloc(msc, win, nr_wins);
     mutex_unlock(&msc->buf_mutex);
 
 free_win:
     kfree(win);
 
     return ret ? ret : size;
 }
 
 static DEVICE_ATTR_RW(nr_pages);
 
 static ssize_t
 win_switch_store(struct device *dev, struct device_attribute *attr,
          const char *buf, size_t size)
 {
     struct msc *msc = dev_get_drvdata(dev);
     unsigned long val;
     int ret;
 
     ret = kstrtoul(buf, 10, &val);
     if (ret)
         return ret;
 
     if (val != 1)
         return -EINVAL;
 
     ret = -EINVAL;
     mutex_lock(&msc->buf_mutex);
     /*
      * Window switch can only happen in the "multi" mode.
      * If a external buffer is engaged, they have the full
      * control over window switching.
      */
     if (msc->mode == MSC_MODE_MULTI && !msc->mbuf)
         ret = msc_win_switch(msc);
     mutex_unlock(&msc->buf_mutex);
 
     return ret ? ret : size;
 }
 
 static DEVICE_ATTR_WO(win_switch);
 
 static ssize_t stop_on_full_show(struct device *dev,
                  struct device_attribute *attr, char *buf)
 {
     struct msc *msc = dev_get_drvdata(dev);
 
     return sprintf(buf, "%d\n", msc->stop_on_full);
 }
 
 static ssize_t stop_on_full_store(struct device *dev,
                   struct device_attribute *attr,
                   const char *buf, size_t size)
 {
     struct msc *msc = dev_get_drvdata(dev);
     int ret;
 
     ret = kstrtobool(buf, &msc->stop_on_full);
     if (ret)
         return ret;
 
     return size;
 }
 
 static DEVICE_ATTR_RW(stop_on_full);
 
 static struct attribute *msc_output_attrs[] = {
     &dev_attr_wrap.attr,
     &dev_attr_mode.attr,
     &dev_attr_nr_pages.attr,
     &dev_attr_win_switch.attr,
     &dev_attr_stop_on_full.attr,
     NULL,
 };
 
 static const struct attribute_group msc_output_group = {
     .attrs  = msc_output_attrs,
 };
 
 static int intel_th_msc_probe(struct intel_th_device *thdev)
 {
     struct device *dev = &thdev->dev;
     struct resource *res;
     struct msc *msc;
     void __iomem *base;
     int err;
 
     res = intel_th_device_get_resource(thdev, IORESOURCE_MEM, 0);
     if (!res)
         return -ENODEV;
 
     base = devm_ioremap(dev, res->start, resource_size(res));
     if (!base)
         return -ENOMEM;
 
     msc = devm_kzalloc(dev, sizeof(*msc), GFP_KERNEL);
     if (!msc)
         return -ENOMEM;
 
     res = intel_th_device_get_resource(thdev, IORESOURCE_IRQ, 1);
     if (!res)
         msc->do_irq = 1;
 
     if (INTEL_TH_CAP(to_intel_th(thdev), multi_is_broken))
         msc->multi_is_broken = 1;
 
     msc->index = thdev->id;
 
     msc->thdev = thdev;
     msc->reg_base = base + msc->index * 0x100;
     msc->msu_base = base;
 
     INIT_WORK(&msc->work, msc_work);
     err = intel_th_msc_init(msc);
     if (err)
         return err;
 
     dev_set_drvdata(dev, msc);
 
     return 0;
 }
 
 static void intel_th_msc_remove(struct intel_th_device *thdev)
 {
     struct msc *msc = dev_get_drvdata(&thdev->dev);
     int ret;
 
     intel_th_msc_deactivate(thdev);
 
     /*
      * Buffers should not be used at this point except if the
      * output character device is still open and the parent
      * device gets detached from its bus, which is a FIXME.
      */
     ret = msc_buffer_free_unless_used(msc);
     WARN_ON_ONCE(ret);
 }
 
 static struct intel_th_driver intel_th_msc_driver = {
     .probe  = intel_th_msc_probe,
     .remove = intel_th_msc_remove,
     .irq        = intel_th_msc_interrupt,
     .wait_empty = intel_th_msc_wait_empty,
     .activate   = intel_th_msc_activate,
     .deactivate = intel_th_msc_deactivate,
     .fops   = &intel_th_msc_fops,
     .attr_group = &msc_output_group,
     .driver = {
         .name   = "msc",
         .owner  = THIS_MODULE,
     },
 };
 
 module_driver(intel_th_msc_driver,
           intel_th_driver_register,
           intel_th_driver_unregister);
 
 MODULE_LICENSE("GPL v2");
 MODULE_DESCRIPTION("Intel(R) Trace Hub Memory Storage Unit driver");
 MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");

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