[PATCH v5 05/18] 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 and warn user
redundant setting, like "cpufreq=hwp;hwp;xen"

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
---
 xen/drivers/cpufreq/cpufreq.c | 57 ++++++++++++++++++++++++++++++-----
 1 file changed, 49 insertions(+), 8 deletions(-)

diff --git a/xen/drivers/cpufreq/cpufreq.c b/xen/drivers/cpufreq/cpufreq.c
index d6b6c844d8..d1b51c8dd0 100644
--- a/xen/drivers/cpufreq/cpufreq.c
+++ b/xen/drivers/cpufreq/cpufreq.c
@@ -69,8 +69,55 @@ enum cpufreq_xen_opt __initdata cpufreq_xen_opts[2] = { 
CPUFREQ_xen,
                                                         CPUFREQ_none };
 unsigned int __initdata cpufreq_xen_cnt = 1;
 
+static const char __initconst cpufreq_opts_str[][5] = {
+    [CPUFREQ_none] = "none",
+    [CPUFREQ_xen] = "xen",
+    [CPUFREQ_hwp] = "hwp",
+};
+
 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) )
+    {
+        printk(XENLOG_WARNING "Duplicate cpufreq driver option: %s\n",
+               cpufreq_opts_str[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:
+        ret = -EINVAL;
+        break;
+    }
+
+    return ret;
+}
+
 static int __init cf_check setup_cpufreq_option(const char *str)
 {
     const char *arg = strpbrk(str, ",:;");
@@ -114,20 +161,14 @@ 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;
+            ret = handle_cpufreq_cmdline(CPUFREQ_xen);
             if ( 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;
+            ret = handle_cpufreq_cmdline(CPUFREQ_hwp);
             if ( arg[0] && arg[1] )
                 ret = hwp_cmdline_parse(arg + 1, end);
         }
-- 
2.34.1