[PATCH v7 05/13] xen/cpufreq: refactor cmdline "cpufreq=xxx"

[Penny Zheng <Penny.Zheng@xxxxxxx>]

A helper function handle_cpufreq_cmdline() is introduced to tidy different
handling pathes.
We also add a new helper cpufreq_opts_contain() to ignore redundant setting,
like "cpufreq=hwp;hwp;xen"
As only slot 0 of cpufreq_xen_opts[] needs explicit initializing with
non-zero CPUFREQ_xen, dropping full array initializer could avoid touching
initializer every time it grows

Signed-off-by: Penny Zheng <Penny.Zheng@xxxxxxx>
---
v2 -> v3:
- new commit
---
v3 -> v4:
- add one single helper to do the tidy work
- ignore and warn user redundant setting
---
v4 -> v5:
- make "cpufreq_opts_str" static and the string literals end up in
  .init.rodata.
- use "CPUFREQ_xxx" as array slot index
- blank line between non-fall-through case blocks
---
v5 -> v6:
- change to "while ( count-- )"
- remove unnecessary warning
- add an assertion to ensure not overruning the array
- add ASSERT_UNREACHABLE()
- check ret of handle_cpufreq_cmdline() and error out
---
v6 -> v7:
- remove overrun assertion as we already have check in setup_cpufreq_option()
- drop full array initializer
---
 xen/drivers/cpufreq/cpufreq.c | 55 +++++++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 12 deletions(-)

diff --git a/xen/drivers/cpufreq/cpufreq.c b/xen/drivers/cpufreq/cpufreq.c
index efba141418..de17e53708 100644
--- a/xen/drivers/cpufreq/cpufreq.c
+++ b/xen/drivers/cpufreq/cpufreq.c
@@ -64,12 +64,49 @@ LIST_HEAD_READ_MOSTLY(cpufreq_governor_list);
 /* set xen as default cpufreq */
 enum cpufreq_controller cpufreq_controller = FREQCTL_xen;
 
-enum cpufreq_xen_opt __initdata cpufreq_xen_opts[2] = { CPUFREQ_xen,
-                                                        CPUFREQ_none };
+enum cpufreq_xen_opt __initdata cpufreq_xen_opts[2] = { CPUFREQ_xen };
 unsigned int __initdata cpufreq_xen_cnt = 1;
 
 static int __init cpufreq_cmdline_parse(const char *s, const char *e);
 
+static bool __init cpufreq_opts_contain(enum cpufreq_xen_opt option)
+{
+    unsigned int count = cpufreq_xen_cnt;
+
+    while ( count-- )
+    {
+        if ( cpufreq_xen_opts[count] == option )
+            return true;
+    }
+
+    return false;
+}
+
+static int __init handle_cpufreq_cmdline(enum cpufreq_xen_opt option)
+{
+    int ret = 0;
+
+    if ( cpufreq_opts_contain(option) )
+        return 0;
+
+    cpufreq_controller = FREQCTL_xen;
+    cpufreq_xen_opts[cpufreq_xen_cnt++] = option;
+    switch ( option )
+    {
+    case CPUFREQ_hwp:
+    case CPUFREQ_xen:
+        xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
+        break;
+
+    default:
+        ASSERT_UNREACHABLE();
+        ret = -EINVAL;
+        break;
+    }
+
+    return ret;
+}
+
 static int __init cf_check setup_cpufreq_option(const char *str)
 {
     const char *arg = strpbrk(str, ",:;");
@@ -113,21 +150,15 @@ static int __init cf_check setup_cpufreq_option(const 
char *str)
 
         if ( choice > 0 || !cmdline_strcmp(str, "xen") )
         {
-            xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
-            cpufreq_controller = FREQCTL_xen;
-            cpufreq_xen_opts[cpufreq_xen_cnt++] = CPUFREQ_xen;
-            ret = 0;
-            if ( arg[0] && arg[1] )
+            ret = handle_cpufreq_cmdline(CPUFREQ_xen);
+            if ( !ret && arg[0] && arg[1] )
                 ret = cpufreq_cmdline_parse(arg + 1, end);
         }
         else if ( IS_ENABLED(CONFIG_INTEL) && choice < 0 &&
                   !cmdline_strcmp(str, "hwp") )
         {
-            xen_processor_pmbits |= XEN_PROCESSOR_PM_PX;
-            cpufreq_controller = FREQCTL_xen;
-            cpufreq_xen_opts[cpufreq_xen_cnt++] = CPUFREQ_hwp;
-            ret = 0;
-            if ( arg[0] && arg[1] )
+            ret = handle_cpufreq_cmdline(CPUFREQ_hwp);
+            if ( !ret && arg[0] && arg[1] )
                 ret = hwp_cmdline_parse(arg + 1, end);
         }
         else
-- 
2.34.1