Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 1032 insertions, 0 deletions

diff --git a/drivers/video/fbdev/skeletonfb.c b/drivers/video/fbdev/skeletonfb.c
new file mode 100644
index 000000000..7e98850d9
--- /dev/null
+++ b/drivers/video/fbdev/skeletonfb.c
@@ -0,0 +1,1032 @@
+/*
+ * linux/drivers/video/skeletonfb.c -- Skeleton for a frame buffer device
+ *
+ *  Modified to new api Jan 2001 by James Simmons (jsimmons@transvirtual.com)
+ *
+ *  Created 28 Dec 1997 by Geert Uytterhoeven
+ *
+ *
+ *  I have started rewriting this driver as a example of the upcoming new API
+ *  The primary goal is to remove the console code from fbdev and place it
+ *  into fbcon.c. This reduces the code and makes writing a new fbdev driver
+ *  easy since the author doesn't need to worry about console internals. It
+ *  also allows the ability to run fbdev without a console/tty system on top
+ *  of it.
+ *
+ *  First the roles of struct fb_info and struct display have changed. Struct
+ *  display will go away. The way the new framebuffer console code will
+ *  work is that it will act to translate data about the tty/console in
+ *  struct vc_data to data in a device independent way in struct fb_info. Then
+ *  various functions in struct fb_ops will be called to store the device
+ *  dependent state in the par field in struct fb_info and to change the
+ *  hardware to that state. This allows a very clean separation of the fbdev
+ *  layer from the console layer. It also allows one to use fbdev on its own
+ *  which is a bounus for embedded devices. The reason this approach works is
+ *  for each framebuffer device when used as a tty/console device is allocated
+ *  a set of virtual terminals to it. Only one virtual terminal can be active
+ *  per framebuffer device. We already have all the data we need in struct
+ *  vc_data so why store a bunch of colormaps and other fbdev specific data
+ *  per virtual terminal.
+ *
+ *  As you can see doing this makes the con parameter pretty much useless
+ *  for struct fb_ops functions, as it should be. Also having struct
+ *  fb_var_screeninfo and other data in fb_info pretty much eliminates the
+ *  need for get_fix and get_var. Once all drivers use the fix, var, and cmap
+ *  fbcon can be written around these fields. This will also eliminate the
+ *  need to regenerate struct fb_var_screeninfo, struct fb_fix_screeninfo
+ *  struct fb_cmap every time get_var, get_fix, get_cmap functions are called
+ *  as many drivers do now.
+ *
+ *  This file is subject to the terms and conditions of the GNU General Public
+ *  License. See the file COPYING in the main directory of this archive for
+ *  more details.
+ */
+
+#include <linux/aperture.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/delay.h>
+#include <linux/fb.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+
+    /*
+     *  This is just simple sample code.
+     *
+     *  No warranty that it actually compiles.
+     *  Even less warranty that it actually works :-)
+     */
+
+/*
+ * Driver data
+ */
+static char *mode_option;
+
+/*
+ *  If your driver supports multiple boards, you should make the
+ *  below data types arrays, or allocate them dynamically (using kmalloc()).
+ */
+
+/*
+ * This structure defines the hardware state of the graphics card. Normally
+ * you place this in a header file in linux/include/video. This file usually
+ * also includes register information. That allows other driver subsystems
+ * and userland applications the ability to use the same header file to
+ * avoid duplicate work and easy porting of software.
+ */
+struct xxx_par;
+
+/*
+ * Here we define the default structs fb_fix_screeninfo and fb_var_screeninfo
+ * if we don't use modedb. If we do use modedb see xxxfb_init how to use it
+ * to get a fb_var_screeninfo. Otherwise define a default var as well.
+ */
+static const struct fb_fix_screeninfo xxxfb_fix = {
+	.id =		"FB's name",
+	.type =		FB_TYPE_PACKED_PIXELS,
+	.visual =	FB_VISUAL_PSEUDOCOLOR,
+	.xpanstep =	1,
+	.ypanstep =	1,
+	.ywrapstep =	1,
+	.accel =	FB_ACCEL_NONE,
+};
+
+    /*
+     * 	Modern graphical hardware not only supports pipelines but some
+     *  also support multiple monitors where each display can have
+     *  its own unique data. In this case each display could be
+     *  represented by a separate framebuffer device thus a separate
+     *  struct fb_info. Now the struct xxx_par represents the graphics
+     *  hardware state thus only one exist per card. In this case the
+     *  struct xxx_par for each graphics card would be shared between
+     *  every struct fb_info that represents a framebuffer on that card.
+     *  This allows when one display changes it video resolution (info->var)
+     *  the other displays know instantly. Each display can always be
+     *  aware of the entire hardware state that affects it because they share
+     *  the same xxx_par struct. The other side of the coin is multiple
+     *  graphics cards that pass data around until it is finally displayed
+     *  on one monitor. Such examples are the voodoo 1 cards and high end
+     *  NUMA graphics servers. For this case we have a bunch of pars, each
+     *  one that represents a graphics state, that belong to one struct
+     *  fb_info. Their you would want to have *par point to a array of device
+     *  states and have each struct fb_ops function deal with all those
+     *  states. I hope this covers every possible hardware design. If not
+     *  feel free to send your ideas at jsimmons@users.sf.net
+     */
+
+    /*
+     *  If your driver supports multiple boards or it supports multiple
+     *  framebuffers, you should make these arrays, or allocate them
+     *  dynamically using framebuffer_alloc() and free them with
+     *  framebuffer_release().
+     */
+static struct fb_info info;
+
+    /*
+     * Each one represents the state of the hardware. Most hardware have
+     * just one hardware state. These here represent the default state(s).
+     */
+static struct xxx_par __initdata current_par;
+
+/**
+ *	xxxfb_open - Optional function. Called when the framebuffer is
+ *		     first accessed.
+ *	@info: frame buffer structure that represents a single frame buffer
+ *	@user: tell us if the userland (value=1) or the console is accessing
+ *	       the framebuffer.
+ *
+ *	This function is the first function called in the framebuffer api.
+ *	Usually you don't need to provide this function. The case where it
+ *	is used is to change from a text mode hardware state to a graphics
+ * 	mode state.
+ *
+ *	Returns negative errno on error, or zero on success.
+ */
+static int xxxfb_open(struct fb_info *info, int user)
+{
+    return 0;
+}
+
+/**
+ *	xxxfb_release - Optional function. Called when the framebuffer
+ *			device is closed.
+ *	@info: frame buffer structure that represents a single frame buffer
+ *	@user: tell us if the userland (value=1) or the console is accessing
+ *	       the framebuffer.
+ *
+ *	Thus function is called when we close /dev/fb or the framebuffer
+ *	console system is released. Usually you don't need this function.
+ *	The case where it is usually used is to go from a graphics state
+ *	to a text mode state.
+ *
+ *	Returns negative errno on error, or zero on success.
+ */
+static int xxxfb_release(struct fb_info *info, int user)
+{
+    return 0;
+}
+
+/**
+ *      xxxfb_check_var - Optional function. Validates a var passed in.
+ *      @var: frame buffer variable screen structure
+ *      @info: frame buffer structure that represents a single frame buffer
+ *
+ *	Checks to see if the hardware supports the state requested by
+ *	var passed in. This function does not alter the hardware state!!!
+ *	This means the data stored in struct fb_info and struct xxx_par do
+ *      not change. This includes the var inside of struct fb_info.
+ *	Do NOT change these. This function can be called on its own if we
+ *	intent to only test a mode and not actually set it. The stuff in
+ *	modedb.c is a example of this. If the var passed in is slightly
+ *	off by what the hardware can support then we alter the var PASSED in
+ *	to what we can do.
+ *
+ *      For values that are off, this function must round them _up_ to the
+ *      next value that is supported by the hardware.  If the value is
+ *      greater than the highest value supported by the hardware, then this
+ *      function must return -EINVAL.
+ *
+ *      Exception to the above rule:  Some drivers have a fixed mode, ie,
+ *      the hardware is already set at boot up, and cannot be changed.  In
+ *      this case, it is more acceptable that this function just return
+ *      a copy of the currently working var (info->var). Better is to not
+ *      implement this function, as the upper layer will do the copying
+ *      of the current var for you.
+ *
+ *      Note:  This is the only function where the contents of var can be
+ *      freely adjusted after the driver has been registered. If you find
+ *      that you have code outside of this function that alters the content
+ *      of var, then you are doing something wrong.  Note also that the
+ *      contents of info->var must be left untouched at all times after
+ *      driver registration.
+ *
+ *	Returns negative errno on error, or zero on success.
+ */
+static int xxxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
+{
+    /* ... */
+    return 0;
+}
+
+/**
+ *      xxxfb_set_par - Optional function. Alters the hardware state.
+ *      @info: frame buffer structure that represents a single frame buffer
+ *
+ *	Using the fb_var_screeninfo in fb_info we set the resolution of the
+ *	this particular framebuffer. This function alters the par AND the
+ *	fb_fix_screeninfo stored in fb_info. It doesn't not alter var in
+ *	fb_info since we are using that data. This means we depend on the
+ *	data in var inside fb_info to be supported by the hardware.
+ *
+ *      This function is also used to recover/restore the hardware to a
+ *      known working state.
+ *
+ *	xxxfb_check_var is always called before xxxfb_set_par to ensure that
+ *      the contents of var is always valid.
+ *
+ *	Again if you can't change the resolution you don't need this function.
+ *
+ *      However, even if your hardware does not support mode changing,
+ *      a set_par might be needed to at least initialize the hardware to
+ *      a known working state, especially if it came back from another
+ *      process that also modifies the same hardware, such as X.
+ *
+ *      If this is the case, a combination such as the following should work:
+ *
+ *      static int xxxfb_check_var(struct fb_var_screeninfo *var,
+ *                                struct fb_info *info)
+ *      {
+ *              *var = info->var;
+ *              return 0;
+ *      }
+ *
+ *      static int xxxfb_set_par(struct fb_info *info)
+ *      {
+ *              init your hardware here
+ *      }
+ *
+ *	Returns negative errno on error, or zero on success.
+ */
+static int xxxfb_set_par(struct fb_info *info)
+{
+    struct xxx_par *par = info->par;
+    /* ... */
+    return 0;
+}
+
+/**
+ *  	xxxfb_setcolreg - Optional function. Sets a color register.
+ *      @regno: Which register in the CLUT we are programming
+ *      @red: The red value which can be up to 16 bits wide
+ *	@green: The green value which can be up to 16 bits wide
+ *	@blue:  The blue value which can be up to 16 bits wide.
+ *	@transp: If supported, the alpha value which can be up to 16 bits wide.
+ *      @info: frame buffer info structure
+ *
+ *  	Set a single color register. The values supplied have a 16 bit
+ *  	magnitude which needs to be scaled in this function for the hardware.
+ *	Things to take into consideration are how many color registers, if
+ *	any, are supported with the current color visual. With truecolor mode
+ *	no color palettes are supported. Here a pseudo palette is created
+ *	which we store the value in pseudo_palette in struct fb_info. For
+ *	pseudocolor mode we have a limited color palette. To deal with this
+ *	we can program what color is displayed for a particular pixel value.
+ *	DirectColor is similar in that we can program each color field. If
+ *	we have a static colormap we don't need to implement this function.
+ *
+ *	Returns negative errno on error, or zero on success.
+ */
+static int xxxfb_setcolreg(unsigned regno, unsigned red, unsigned green,
+			   unsigned blue, unsigned transp,
+			   struct fb_info *info)
+{
+    if (regno >= 256)  /* no. of hw registers */
+       return -EINVAL;
+    /*
+     * Program hardware... do anything you want with transp
+     */
+
+    /* grayscale works only partially under directcolor */
+    if (info->var.grayscale) {
+       /* grayscale = 0.30*R + 0.59*G + 0.11*B */
+       red = green = blue = (red * 77 + green * 151 + blue * 28) >> 8;
+    }
+
+    /* Directcolor:
+     *   var->{color}.offset contains start of bitfield
+     *   var->{color}.length contains length of bitfield
+     *   {hardwarespecific} contains width of DAC
+     *   pseudo_palette[X] is programmed to (X << red.offset) |
+     *                                      (X << green.offset) |
+     *                                      (X << blue.offset)
+     *   RAMDAC[X] is programmed to (red, green, blue)
+     *   color depth = SUM(var->{color}.length)
+     *
+     * Pseudocolor:
+     *    var->{color}.offset is 0 unless the palette index takes less than
+     *                        bits_per_pixel bits and is stored in the upper
+     *                        bits of the pixel value
+     *    var->{color}.length is set so that 1 << length is the number of
+     *                        available palette entries
+     *    pseudo_palette is not used
+     *    RAMDAC[X] is programmed to (red, green, blue)
+     *    color depth = var->{color}.length
+     *
+     * Static pseudocolor:
+     *    same as Pseudocolor, but the RAMDAC is not programmed (read-only)
+     *
+     * Mono01/Mono10:
+     *    Has only 2 values, black on white or white on black (fg on bg),
+     *    var->{color}.offset is 0
+     *    white = (1 << var->{color}.length) - 1, black = 0
+     *    pseudo_palette is not used
+     *    RAMDAC does not exist
+     *    color depth is always 2
+     *
+     * Truecolor:
+     *    does not use RAMDAC (usually has 3 of them).
+     *    var->{color}.offset contains start of bitfield
+     *    var->{color}.length contains length of bitfield
+     *    pseudo_palette is programmed to (red << red.offset) |
+     *                                    (green << green.offset) |
+     *                                    (blue << blue.offset) |
+     *                                    (transp << transp.offset)
+     *    RAMDAC does not exist
+     *    color depth = SUM(var->{color}.length})
+     *
+     *  The color depth is used by fbcon for choosing the logo and also
+     *  for color palette transformation if color depth < 4
+     *
+     *  As can be seen from the above, the field bits_per_pixel is _NOT_
+     *  a criteria for describing the color visual.
+     *
+     *  A common mistake is assuming that bits_per_pixel <= 8 is pseudocolor,
+     *  and higher than that, true/directcolor.  This is incorrect, one needs
+     *  to look at the fix->visual.
+     *
+     *  Another common mistake is using bits_per_pixel to calculate the color
+     *  depth.  The bits_per_pixel field does not directly translate to color
+     *  depth. You have to compute for the color depth (using the color
+     *  bitfields) and fix->visual as seen above.
+     */
+
+    /*
+     * This is the point where the color is converted to something that
+     * is acceptable by the hardware.
+     */
+#define CNVT_TOHW(val,width) ((((val)<<(width))+0x7FFF-(val))>>16)
+    red = CNVT_TOHW(red, info->var.red.length);
+    green = CNVT_TOHW(green, info->var.green.length);
+    blue = CNVT_TOHW(blue, info->var.blue.length);
+    transp = CNVT_TOHW(transp, info->var.transp.length);
+#undef CNVT_TOHW
+    /*
+     * This is the point where the function feeds the color to the hardware
+     * palette after converting the colors to something acceptable by
+     * the hardware. Note, only FB_VISUAL_DIRECTCOLOR and
+     * FB_VISUAL_PSEUDOCOLOR visuals need to write to the hardware palette.
+     * If you have code that writes to the hardware CLUT, and it's not
+     * any of the above visuals, then you are doing something wrong.
+     */
+    if (info->fix.visual == FB_VISUAL_DIRECTCOLOR ||
+	info->fix.visual == FB_VISUAL_TRUECOLOR)
+	    write_{red|green|blue|transp}_to_clut();
+
+    /* This is the point were you need to fill up the contents of
+     * info->pseudo_palette. This structure is used _only_ by fbcon, thus
+     * it only contains 16 entries to match the number of colors supported
+     * by the console. The pseudo_palette is used only if the visual is
+     * in directcolor or truecolor mode.  With other visuals, the
+     * pseudo_palette is not used. (This might change in the future.)
+     *
+     * The contents of the pseudo_palette is in raw pixel format.  Ie, each
+     * entry can be written directly to the framebuffer without any conversion.
+     * The pseudo_palette is (void *).  However, if using the generic
+     * drawing functions (cfb_imageblit, cfb_fillrect), the pseudo_palette
+     * must be casted to (u32 *) _regardless_ of the bits per pixel. If the
+     * driver is using its own drawing functions, then it can use whatever
+     * size it wants.
+     */
+    if (info->fix.visual == FB_VISUAL_TRUECOLOR ||
+	info->fix.visual == FB_VISUAL_DIRECTCOLOR) {
+	    u32 v;
+
+	    if (regno >= 16)
+		    return -EINVAL;
+
+	    v = (red << info->var.red.offset) |
+		    (green << info->var.green.offset) |
+		    (blue << info->var.blue.offset) |
+		    (transp << info->var.transp.offset);
+
+	    ((u32*)(info->pseudo_palette))[regno] = v;
+    }
+
+    /* ... */
+    return 0;
+}
+
+/**
+ *      xxxfb_pan_display - NOT a required function. Pans the display.
+ *      @var: frame buffer variable screen structure
+ *      @info: frame buffer structure that represents a single frame buffer
+ *
+ *	Pan (or wrap, depending on the `vmode' field) the display using the
+ *  	`xoffset' and `yoffset' fields of the `var' structure.
+ *  	If the values don't fit, return -EINVAL.
+ *
+ *      Returns negative errno on error, or zero on success.
+ */
+static int xxxfb_pan_display(struct fb_var_screeninfo *var,
+			     struct fb_info *info)
+{
+    /*
+     * If your hardware does not support panning, _do_ _not_ implement this
+     * function. Creating a dummy function will just confuse user apps.
+     */
+
+    /*
+     * Note that even if this function is fully functional, a setting of
+     * 0 in both xpanstep and ypanstep means that this function will never
+     * get called.
+     */
+
+    /* ... */
+    return 0;
+}
+
+/**
+ *      xxxfb_blank - NOT a required function. Blanks the display.
+ *      @blank_mode: the blank mode we want.
+ *      @info: frame buffer structure that represents a single frame buffer
+ *
+ *      Blank the screen if blank_mode != FB_BLANK_UNBLANK, else unblank.
+ *      Return 0 if blanking succeeded, != 0 if un-/blanking failed due to
+ *      e.g. a video mode which doesn't support it.
+ *
+ *      Implements VESA suspend and powerdown modes on hardware that supports
+ *      disabling hsync/vsync:
+ *
+ *      FB_BLANK_NORMAL = display is blanked, syncs are on.
+ *      FB_BLANK_HSYNC_SUSPEND = hsync off
+ *      FB_BLANK_VSYNC_SUSPEND = vsync off
+ *      FB_BLANK_POWERDOWN =  hsync and vsync off
+ *
+ *      If implementing this function, at least support FB_BLANK_UNBLANK.
+ *      Return !0 for any modes that are unimplemented.
+ *
+ */
+static int xxxfb_blank(int blank_mode, struct fb_info *info)
+{
+    /* ... */
+    return 0;
+}
+
+/* ------------ Accelerated Functions --------------------- */
+
+/*
+ * We provide our own functions if we have hardware acceleration
+ * or non packed pixel format layouts. If we have no hardware
+ * acceleration, we can use a generic unaccelerated function. If using
+ * a pack pixel format just use the functions in cfb_*.c. Each file
+ * has one of the three different accel functions we support.
+ */
+
+/**
+ *      xxxfb_fillrect - REQUIRED function. Can use generic routines if
+ *		 	 non acclerated hardware and packed pixel based.
+ *			 Draws a rectangle on the screen.
+ *
+ *      @info: frame buffer structure that represents a single frame buffer
+ *	@region: The structure representing the rectangular region we
+ *		 wish to draw to.
+ *
+ *	This drawing operation places/removes a retangle on the screen
+ *	depending on the rastering operation with the value of color which
+ *	is in the current color depth format.
+ */
+void xxxfb_fillrect(struct fb_info *p, const struct fb_fillrect *region)
+{
+/*	Meaning of struct fb_fillrect
+ *
+ *	@dx: The x and y corrdinates of the upper left hand corner of the
+ *	@dy: area we want to draw to.
+ *	@width: How wide the rectangle is we want to draw.
+ *	@height: How tall the rectangle is we want to draw.
+ *	@color:	The color to fill in the rectangle with.
+ *	@rop: The raster operation. We can draw the rectangle with a COPY
+ *	      of XOR which provides erasing effect.
+ */
+}
+
+/**
+ *      xxxfb_copyarea - REQUIRED function. Can use generic routines if
+ *                       non acclerated hardware and packed pixel based.
+ *                       Copies one area of the screen to another area.
+ *
+ *      @info: frame buffer structure that represents a single frame buffer
+ *      @area: Structure providing the data to copy the framebuffer contents
+ *	       from one region to another.
+ *
+ *      This drawing operation copies a rectangular area from one area of the
+ *	screen to another area.
+ */
+void xxxfb_copyarea(struct fb_info *p, const struct fb_copyarea *area)
+{
+/*
+ *      @dx: The x and y coordinates of the upper left hand corner of the
+ *	@dy: destination area on the screen.
+ *      @width: How wide the rectangle is we want to copy.
+ *      @height: How tall the rectangle is we want to copy.
+ *      @sx: The x and y coordinates of the upper left hand corner of the
+ *      @sy: source area on the screen.
+ */
+}
+
+
+/**
+ *      xxxfb_imageblit - REQUIRED function. Can use generic routines if
+ *                        non acclerated hardware and packed pixel based.
+ *                        Copies a image from system memory to the screen.
+ *
+ *      @info: frame buffer structure that represents a single frame buffer
+ *	@image:	structure defining the image.
+ *
+ *      This drawing operation draws a image on the screen. It can be a
+ *	mono image (needed for font handling) or a color image (needed for
+ *	tux).
+ */
+void xxxfb_imageblit(struct fb_info *p, const struct fb_image *image)
+{
+/*
+ *      @dx: The x and y coordinates of the upper left hand corner of the
+ *	@dy: destination area to place the image on the screen.
+ *      @width: How wide the image is we want to copy.
+ *      @height: How tall the image is we want to copy.
+ *      @fg_color: For mono bitmap images this is color data for
+ *      @bg_color: the foreground and background of the image to
+ *		   write directly to the frmaebuffer.
+ *	@depth:	How many bits represent a single pixel for this image.
+ *	@data: The actual data used to construct the image on the display.
+ *	@cmap: The colormap used for color images.
+ */
+
+/*
+ * The generic function, cfb_imageblit, expects that the bitmap scanlines are
+ * padded to the next byte.  Most hardware accelerators may require padding to
+ * the next u16 or the next u32.  If that is the case, the driver can specify
+ * this by setting info->pixmap.scan_align = 2 or 4.  See a more
+ * comprehensive description of the pixmap below.
+ */
+}
+
+/**
+ *	xxxfb_cursor - 	OPTIONAL. If your hardware lacks support
+ *			for a cursor, leave this field NULL.
+ *
+ *      @info: frame buffer structure that represents a single frame buffer
+ *	@cursor: structure defining the cursor to draw.
+ *
+ *      This operation is used to set or alter the properities of the
+ *	cursor.
+ *
+ *	Returns negative errno on error, or zero on success.
+ */
+int xxxfb_cursor(struct fb_info *info, struct fb_cursor *cursor)
+{
+/*
+ *      @set: 	Which fields we are altering in struct fb_cursor
+ *	@enable: Disable or enable the cursor
+ *      @rop: 	The bit operation we want to do.
+ *      @mask:  This is the cursor mask bitmap.
+ *      @dest:  A image of the area we are going to display the cursor.
+ *		Used internally by the driver.
+ *      @hot:	The hot spot.
+ *	@image:	The actual data for the cursor image.
+ *
+ *      NOTES ON FLAGS (cursor->set):
+ *
+ *      FB_CUR_SETIMAGE - the cursor image has changed (cursor->image.data)
+ *      FB_CUR_SETPOS   - the cursor position has changed (cursor->image.dx|dy)
+ *      FB_CUR_SETHOT   - the cursor hot spot has changed (cursor->hot.dx|dy)
+ *      FB_CUR_SETCMAP  - the cursor colors has changed (cursor->fg_color|bg_color)
+ *      FB_CUR_SETSHAPE - the cursor bitmask has changed (cursor->mask)
+ *      FB_CUR_SETSIZE  - the cursor size has changed (cursor->width|height)
+ *      FB_CUR_SETALL   - everything has changed
+ *
+ *      NOTES ON ROPs (cursor->rop, Raster Operation)
+ *
+ *      ROP_XOR         - cursor->image.data XOR cursor->mask
+ *      ROP_COPY        - curosr->image.data AND cursor->mask
+ *
+ *      OTHER NOTES:
+ *
+ *      - fbcon only supports a 2-color cursor (cursor->image.depth = 1)
+ *      - The fb_cursor structure, @cursor, _will_ always contain valid
+ *        fields, whether any particular bitfields in cursor->set is set
+ *        or not.
+ */
+}
+
+/**
+ *	xxxfb_sync - NOT a required function. Normally the accel engine
+ *		     for a graphics card take a specific amount of time.
+ *		     Often we have to wait for the accelerator to finish
+ *		     its operation before we can write to the framebuffer
+ *		     so we can have consistent display output.
+ *
+ *      @info: frame buffer structure that represents a single frame buffer
+ *
+ *      If the driver has implemented its own hardware-based drawing function,
+ *      implementing this function is highly recommended.
+ */
+int xxxfb_sync(struct fb_info *info)
+{
+	return 0;
+}
+
+    /*
+     *  Frame buffer operations
+     */
+
+static const struct fb_ops xxxfb_ops = {
+	.owner		= THIS_MODULE,
+	.fb_open	= xxxfb_open,
+	.fb_read	= xxxfb_read,
+	.fb_write	= xxxfb_write,
+	.fb_release	= xxxfb_release,
+	.fb_check_var	= xxxfb_check_var,
+	.fb_set_par	= xxxfb_set_par,
+	.fb_setcolreg	= xxxfb_setcolreg,
+	.fb_blank	= xxxfb_blank,
+	.fb_pan_display	= xxxfb_pan_display,
+	.fb_fillrect	= xxxfb_fillrect, 	/* Needed !!! */
+	.fb_copyarea	= xxxfb_copyarea,	/* Needed !!! */
+	.fb_imageblit	= xxxfb_imageblit,	/* Needed !!! */
+	.fb_cursor	= xxxfb_cursor,		/* Optional !!! */
+	.fb_sync	= xxxfb_sync,
+	.fb_ioctl	= xxxfb_ioctl,
+	.fb_mmap	= xxxfb_mmap,
+};
+
+/* ------------------------------------------------------------------------- */
+
+    /*
+     *  Initialization
+     */
+
+/* static int __init xxfb_probe (struct platform_device *pdev) -- for platform devs */
+static int xxxfb_probe(struct pci_dev *dev, const struct pci_device_id *ent)
+{
+    struct fb_info *info;
+    struct xxx_par *par;
+    struct device *device = &dev->dev; /* or &pdev->dev */
+    int cmap_len, retval;
+
+    /*
+     * Remove firmware-based drivers that create resource conflicts.
+     */
+    retval = aperture_remove_conflicting_pci_devices(pdev, "xxxfb");
+    if (retval)
+	    return retval;
+
+    /*
+     * Dynamically allocate info and par
+     */
+    info = framebuffer_alloc(sizeof(struct xxx_par), device);
+
+    if (!info) {
+	    /* goto error path */
+    }
+
+    par = info->par;
+
+    /*
+     * Here we set the screen_base to the virtual memory address
+     * for the framebuffer. Usually we obtain the resource address
+     * from the bus layer and then translate it to virtual memory
+     * space via ioremap. Consult ioport.h.
+     */
+    info->screen_base = framebuffer_virtual_memory;
+    info->fbops = &xxxfb_ops;
+    info->fix = xxxfb_fix;
+    info->pseudo_palette = pseudo_palette; /* The pseudopalette is an
+					    * 16-member array
+					    */
+    /*
+     * Set up flags to indicate what sort of acceleration your
+     * driver can provide (pan/wrap/copyarea/etc.) and whether it
+     * is a module -- see FBINFO_* in include/linux/fb.h
+     *
+     * If your hardware can support any of the hardware accelerated functions
+     * fbcon performance will improve if info->flags is set properly.
+     *
+     * FBINFO_HWACCEL_COPYAREA - hardware moves
+     * FBINFO_HWACCEL_FILLRECT - hardware fills
+     * FBINFO_HWACCEL_IMAGEBLIT - hardware mono->color expansion
+     * FBINFO_HWACCEL_YPAN - hardware can pan display in y-axis
+     * FBINFO_HWACCEL_YWRAP - hardware can wrap display in y-axis
+     * FBINFO_HWACCEL_DISABLED - supports hardware accels, but disabled
+     * FBINFO_READS_FAST - if set, prefer moves over mono->color expansion
+     * FBINFO_MISC_TILEBLITTING - hardware can do tile blits
+     *
+     * NOTE: These are for fbcon use only.
+     */
+    info->flags = 0;
+
+/********************* This stage is optional ******************************/
+     /*
+     * The struct pixmap is a scratch pad for the drawing functions. This
+     * is where the monochrome bitmap is constructed by the higher layers
+     * and then passed to the accelerator.  For drivers that uses
+     * cfb_imageblit, you can skip this part.  For those that have a more
+     * rigorous requirement, this stage is needed
+     */
+
+    /* PIXMAP_SIZE should be small enough to optimize drawing, but not
+     * large enough that memory is wasted.  A safe size is
+     * (max_xres * max_font_height/8). max_xres is driver dependent,
+     * max_font_height is 32.
+     */
+    info->pixmap.addr = kmalloc(PIXMAP_SIZE, GFP_KERNEL);
+    if (!info->pixmap.addr) {
+	    /* goto error */
+    }
+
+    info->pixmap.size = PIXMAP_SIZE;
+
+    /*
+     * FB_PIXMAP_SYSTEM - memory is in system ram
+     * FB_PIXMAP_IO     - memory is iomapped
+     * FB_PIXMAP_SYNC   - if set, will call fb_sync() per access to pixmap,
+     *                    usually if FB_PIXMAP_IO is set.
+     *
+     * Currently, FB_PIXMAP_IO is unimplemented.
+     */
+    info->pixmap.flags = FB_PIXMAP_SYSTEM;
+
+    /*
+     * scan_align is the number of padding for each scanline.  It is in bytes.
+     * Thus for accelerators that need padding to the next u32, put 4 here.
+     */
+    info->pixmap.scan_align = 4;
+
+    /*
+     * buf_align is the amount to be padded for the buffer. For example,
+     * the i810fb needs a scan_align of 2 but expects it to be fed with
+     * dwords, so a buf_align = 4 is required.
+     */
+    info->pixmap.buf_align = 4;
+
+    /* access_align is how many bits can be accessed from the framebuffer
+     * ie. some epson cards allow 16-bit access only.  Most drivers will
+     * be safe with u32 here.
+     *
+     * NOTE: This field is currently unused.
+     */
+    info->pixmap.access_align = 32;
+/***************************** End optional stage ***************************/
+
+    /*
+     * This should give a reasonable default video mode. The following is
+     * done when we can set a video mode.
+     */
+    if (!mode_option)
+	mode_option = "640x480@60";
+
+    retval = fb_find_mode(&info->var, info, mode_option, NULL, 0, NULL, 8);
+
+    if (!retval || retval == 4)
+	return -EINVAL;
+
+    /* This has to be done! */
+    if (fb_alloc_cmap(&info->cmap, cmap_len, 0))
+	return -ENOMEM;
+
+    /*
+     * The following is done in the case of having hardware with a static
+     * mode. If we are setting the mode ourselves we don't call this.
+     */
+    info->var = xxxfb_var;
+
+    /*
+     * For drivers that can...
+     */
+    xxxfb_check_var(&info->var, info);
+
+    /*
+     * Does a call to fb_set_par() before register_framebuffer needed?  This
+     * will depend on you and the hardware.  If you are sure that your driver
+     * is the only device in the system, a call to fb_set_par() is safe.
+     *
+     * Hardware in x86 systems has a VGA core.  Calling set_par() at this
+     * point will corrupt the VGA console, so it might be safer to skip a
+     * call to set_par here and just allow fbcon to do it for you.
+     */
+    /* xxxfb_set_par(info); */
+
+    if (register_framebuffer(info) < 0) {
+	fb_dealloc_cmap(&info->cmap);
+	return -EINVAL;
+    }
+    fb_info(info, "%s frame buffer device\n", info->fix.id);
+    pci_set_drvdata(dev, info); /* or platform_set_drvdata(pdev, info) */
+    return 0;
+}
+
+    /*
+     *  Cleanup
+     */
+/* static void xxxfb_remove(struct platform_device *pdev) */
+static void xxxfb_remove(struct pci_dev *dev)
+{
+	struct fb_info *info = pci_get_drvdata(dev);
+	/* or platform_get_drvdata(pdev); */
+
+	if (info) {
+		unregister_framebuffer(info);
+		fb_dealloc_cmap(&info->cmap);
+		/* ... */
+		framebuffer_release(info);
+	}
+}
+
+#ifdef CONFIG_PCI
+#ifdef CONFIG_PM
+/**
+ *	xxxfb_suspend - Optional but recommended function. Suspend the device.
+ *	@dev: PCI device
+ *	@msg: the suspend event code.
+ *
+ *      See Documentation/driver-api/pm/devices.rst for more information
+ */
+static int xxxfb_suspend(struct device *dev)
+{
+	struct fb_info *info = dev_get_drvdata(dev);
+	struct xxxfb_par *par = info->par;
+
+	/* suspend here */
+	return 0;
+}
+
+/**
+ *	xxxfb_resume - Optional but recommended function. Resume the device.
+ *	@dev: PCI device
+ *
+ *      See Documentation/driver-api/pm/devices.rst for more information
+ */
+static int xxxfb_resume(struct device *dev)
+{
+	struct fb_info *info = dev_get_drvdata(dev);
+	struct xxxfb_par *par = info->par;
+
+	/* resume here */
+	return 0;
+}
+#else
+#define xxxfb_suspend NULL
+#define xxxfb_resume NULL
+#endif /* CONFIG_PM */
+
+static const struct pci_device_id xxxfb_id_table[] = {
+	{ PCI_VENDOR_ID_XXX, PCI_DEVICE_ID_XXX,
+	  PCI_ANY_ID, PCI_ANY_ID, PCI_BASE_CLASS_DISPLAY << 16,
+	  PCI_CLASS_MASK, 0 },
+	{ 0, }
+};
+
+static SIMPLE_DEV_PM_OPS(xxxfb_pm_ops, xxxfb_suspend, xxxfb_resume);
+
+/* For PCI drivers */
+static struct pci_driver xxxfb_driver = {
+	.name =		"xxxfb",
+	.id_table =	xxxfb_id_table,
+	.probe =	xxxfb_probe,
+	.remove =	xxxfb_remove,
+	.driver.pm =	xxxfb_pm_ops, /* optional but recommended */
+};
+
+MODULE_DEVICE_TABLE(pci, xxxfb_id_table);
+
+static int __init xxxfb_init(void)
+{
+	/*
+	 *  For kernel boot options (in 'video=xxxfb:<options>' format)
+	 */
+#ifndef MODULE
+	char *option = NULL;
+
+	if (fb_get_options("xxxfb", &option))
+		return -ENODEV;
+	xxxfb_setup(option);
+#endif
+
+	return pci_register_driver(&xxxfb_driver);
+}
+
+static void __exit xxxfb_exit(void)
+{
+	pci_unregister_driver(&xxxfb_driver);
+}
+#else /* non PCI, platform drivers */
+#include <linux/platform_device.h>
+/* for platform devices */
+
+#ifdef CONFIG_PM
+/**
+ *	xxxfb_suspend - Optional but recommended function. Suspend the device.
+ *	@dev: platform device
+ *	@msg: the suspend event code.
+ *
+ *      See Documentation/driver-api/pm/devices.rst for more information
+ */
+static int xxxfb_suspend(struct platform_device *dev, pm_message_t msg)
+{
+	struct fb_info *info = platform_get_drvdata(dev);
+	struct xxxfb_par *par = info->par;
+
+	/* suspend here */
+	return 0;
+}
+
+/**
+ *	xxxfb_resume - Optional but recommended function. Resume the device.
+ *	@dev: platform device
+ *
+ *      See Documentation/driver-api/pm/devices.rst for more information
+ */
+static int xxxfb_resume(struct platform_dev *dev)
+{
+	struct fb_info *info = platform_get_drvdata(dev);
+	struct xxxfb_par *par = info->par;
+
+	/* resume here */
+	return 0;
+}
+#else
+#define xxxfb_suspend NULL
+#define xxxfb_resume NULL
+#endif /* CONFIG_PM */
+
+static struct platform_device_driver xxxfb_driver = {
+	.probe = xxxfb_probe,
+	.remove = xxxfb_remove,
+	.suspend = xxxfb_suspend, /* optional but recommended */
+	.resume = xxxfb_resume,   /* optional but recommended */
+	.driver = {
+		.name = "xxxfb",
+	},
+};
+
+static struct platform_device *xxxfb_device;
+
+#ifndef MODULE
+    /*
+     *  Setup
+     */
+
+/*
+ * Only necessary if your driver takes special options,
+ * otherwise we fall back on the generic fb_setup().
+ */
+static int __init xxxfb_setup(char *options)
+{
+    /* Parse user specified options (`video=xxxfb:') */
+}
+#endif /* MODULE */
+
+static int __init xxxfb_init(void)
+{
+	int ret;
+	/*
+	 *  For kernel boot options (in 'video=xxxfb:<options>' format)
+	 */
+#ifndef MODULE
+	char *option = NULL;
+#endif
+
+	if (fb_modesetting_disabled("xxxfb"))
+		return -ENODEV;
+
+#ifndef MODULE
+	if (fb_get_options("xxxfb", &option))
+		return -ENODEV;
+	xxxfb_setup(option);
+#endif
+	ret = platform_driver_register(&xxxfb_driver);
+
+	if (!ret) {
+		xxxfb_device = platform_device_register_simple("xxxfb", 0,
+								NULL, 0);
+
+		if (IS_ERR(xxxfb_device)) {
+			platform_driver_unregister(&xxxfb_driver);
+			ret = PTR_ERR(xxxfb_device);
+		}
+	}
+
+	return ret;
+}
+
+static void __exit xxxfb_exit(void)
+{
+	platform_device_unregister(xxxfb_device);
+	platform_driver_unregister(&xxxfb_driver);
+}
+#endif /* CONFIG_PCI */
+
+/* ------------------------------------------------------------------------- */
+
+
+    /*
+     *  Modularization
+     */
+
+module_init(xxxfb_init);
+module_exit(xxxfb_exit);
+
+MODULE_LICENSE("GPL");