The i915 DRM driver very cleverly used ascii85 encoding for their
GPU state file. Move the encode functions to a general header file to
support other drivers that might be interested in the same
functionality.

[v2 - Update the API to be cleaner for the caller suggested by
Chris Wilson]

Signed-off-by: Jordan Crouse <jcro...@codeaurora.org>
---
 drivers/gpu/drm/i915/i915_gpu_error.c | 38 ++++++----------------------------
 include/linux/ascii85.h               | 39 +++++++++++++++++++++++++++++++++++
 2 files changed, 45 insertions(+), 32 deletions(-)
 create mode 100644 include/linux/ascii85.h

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c 
b/drivers/gpu/drm/i915/i915_gpu_error.c
index 9440593..8bc72c7 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -31,6 +31,7 @@
 #include <linux/stop_machine.h>
 #include <linux/zlib.h>
 #include <drm/drm_print.h>
+#include <linux/ascii85.h>
 
 #include "i915_drv.h"
 
@@ -502,35 +503,12 @@ void i915_error_printf(struct drm_i915_error_state_buf 
*e, const char *f, ...)
        va_end(args);
 }
 
-static int
-ascii85_encode_len(int len)
-{
-       return DIV_ROUND_UP(len, 4);
-}
-
-static bool
-ascii85_encode(u32 in, char *out)
-{
-       int i;
-
-       if (in == 0)
-               return false;
-
-       out[5] = '\0';
-       for (i = 5; i--; ) {
-               out[i] = '!' + in % 85;
-               in /= 85;
-       }
-
-       return true;
-}
-
 static void print_error_obj(struct drm_i915_error_state_buf *m,
                            struct intel_engine_cs *engine,
                            const char *name,
                            struct drm_i915_error_object *obj)
 {
-       char out[6];
+       char out[ASCII85_BUFSZ];
        int page;
 
        if (!obj)
@@ -545,19 +523,15 @@ static void print_error_obj(struct 
drm_i915_error_state_buf *m,
 
        err_compression_marker(m);
        for (page = 0; page < obj->page_count; page++) {
-               int i, len;
+               int i;
+               long len = PAGE_SIZE;
 
-               len = PAGE_SIZE;
                if (page == obj->page_count - 1)
                        len -= obj->unused;
                len = ascii85_encode_len(len);
 
-               for (i = 0; i < len; i++) {
-                       if (ascii85_encode(obj->pages[page][i], out))
-                               err_puts(m, out);
-                       else
-                               err_puts(m, "z");
-               }
+               for (i = 0; i < len; i++)
+                       error_puts(m, ascii85_encode(obj->pages[page][i], out));
        }
        err_puts(m, "\n");
 }
diff --git a/include/linux/ascii85.h b/include/linux/ascii85.h
new file mode 100644
index 0000000..322bbed
--- /dev/null
+++ b/include/linux/ascii85.h
@@ -0,0 +1,39 @@
+
+/*
+ * SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (c) 2008 Intel Corporation
+ * Copyright (c) The Linux Foundation. All rights reserved.
+ */
+
+#ifndef _ASCII85_H_
+#define _ASCII85_H_
+
+#include <linux/kernel.h>
+
+#define ASCII85_BUFSZ 6
+
+static inline long
+ascii85_encode_len(long len)
+{
+       return DIV_ROUND_UP(len, 4);
+}
+
+static inline char *
+ascii85_encode(u32 in, char *out)
+{
+       int i;
+
+       if (in == 0)
+               return "z";
+
+       out[5] = '\0';
+       for (i = 5; i--; ) {
+               out[i] = '!' + in % 85;
+               in /= 85;
+       }
+
+       return out;
+}
+
+#endif
-- 
1.9.1

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