include: Move ascii85 functions from i915 to linux/ascii85.h

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.

v4: Make the return value const char * as suggested by Chris Wilson
v3: Fix error_puts -> err_puts pointed out by the 01.org bot
v2: Update API to be cleaner for the caller as suggested by Chris Wilson

Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>

2 files changed, 42 insertions, 30 deletions

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 8c81cf3aa182..f7f2aa71d8d9 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_gpu_error.h"
 #include "i915_drv.h"
@@ -517,35 +518,12 @@ 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)
@@ -567,12 +545,8 @@ static void print_error_obj(struct drm_i915_error_state_buf *m,
                         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++)
+                        err_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 000000000000..4cc40201273e
--- /dev/null
+++ b/include/linux/ascii85.h
@@ -0,0 +1,38 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright (c) 2008 Intel Corporation
+ * Copyright (c) 2018 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 const 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