[RFC][PATCH 1/2] cpufreq: intel_pstate: Expose global sysfs attributes upfront

[Rafael J. Wysocki]

From: Rafael J. Wysocki <rafael.j.wyso...@intel.com>

Expose the intel_pstate's global sysfs attributes before registering
the driver to prepare for the addition of an attribute that also will
have to work if the driver is not registered.

Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
---
 drivers/cpufreq/intel_pstate.c |   67 +++++++++++++++++++++++++++++++++++++++--
 1 file changed, 65 insertions(+), 2 deletions(-)

Index: linux-pm/drivers/cpufreq/intel_pstate.c
===================================================================
--- linux-pm.orig/drivers/cpufreq/intel_pstate.c
+++ linux-pm/drivers/cpufreq/intel_pstate.c
@@ -358,6 +358,8 @@ static struct pstate_funcs pstate_funcs
 static int hwp_active __read_mostly;
 static bool per_cpu_limits __read_mostly;
 
+static bool driver_registered __read_mostly;
+
 #ifdef CONFIG_ACPI
 static bool acpi_ppc;
 #endif
@@ -394,6 +396,7 @@ static struct perf_limits *limits = &per
 static struct perf_limits *limits = &powersave_limits;
 #endif
 
+static DEFINE_MUTEX(intel_pstate_driver_lock);
 static DEFINE_MUTEX(intel_pstate_limits_lock);
 
 #ifdef CONFIG_ACPI
@@ -1055,12 +1058,22 @@ static ssize_t show_turbo_pct(struct kob
        int total, no_turbo, turbo_pct;
        uint32_t turbo_fp;
 
+       mutex_lock(&intel_pstate_driver_lock);
+
+       if (!driver_registered) {
+               mutex_unlock(&intel_pstate_limits_lock);
+               return -EAGAIN;
+       }
+
        cpu = all_cpu_data[0];
 
        total = cpu->pstate.turbo_pstate - cpu->pstate.min_pstate + 1;
        no_turbo = cpu->pstate.max_pstate - cpu->pstate.min_pstate + 1;
        turbo_fp = div_fp(no_turbo, total);
        turbo_pct = 100 - fp_toint(mul_fp(turbo_fp, int_tofp(100)));
+
+       mutex_unlock(&intel_pstate_driver_lock);
+
        return sprintf(buf, "%u\n", turbo_pct);
 }
 
@@ -1070,8 +1083,18 @@ static ssize_t show_num_pstates(struct k
        struct cpudata *cpu;
        int total;
 
+       mutex_lock(&intel_pstate_driver_lock);
+
+       if (!driver_registered) {
+               mutex_unlock(&intel_pstate_limits_lock);
+               return -EAGAIN;
+       }
+
        cpu = all_cpu_data[0];
        total = cpu->pstate.turbo_pstate - cpu->pstate.min_pstate + 1;
+
+       mutex_unlock(&intel_pstate_driver_lock);
+
        return sprintf(buf, "%u\n", total);
 }
 
@@ -1080,12 +1103,21 @@ static ssize_t show_no_turbo(struct kobj
 {
        ssize_t ret;
 
+       mutex_lock(&intel_pstate_driver_lock);
+
+       if (!driver_registered) {
+               mutex_unlock(&intel_pstate_limits_lock);
+               return -EAGAIN;
+       }
+
        update_turbo_state();
        if (limits->turbo_disabled)
                ret = sprintf(buf, "%u\n", limits->turbo_disabled);
        else
                ret = sprintf(buf, "%u\n", limits->no_turbo);
 
+       mutex_unlock(&intel_pstate_driver_lock);
+
        return ret;
 }
 
@@ -1099,6 +1131,13 @@ static ssize_t store_no_turbo(struct kob
        if (ret != 1)
                return -EINVAL;
 
+       mutex_lock(&intel_pstate_driver_lock);
+
+       if (!driver_registered) {
+               mutex_unlock(&intel_pstate_driver_lock);
+               return -EAGAIN;
+       }
+
        mutex_lock(&intel_pstate_limits_lock);
 
        update_turbo_state();
@@ -1114,6 +1153,8 @@ static ssize_t store_no_turbo(struct kob
 
        intel_pstate_update_policies();
 
+       mutex_unlock(&intel_pstate_driver_lock);
+
        return count;
 }
 
@@ -1127,6 +1168,13 @@ static ssize_t store_max_perf_pct(struct
        if (ret != 1)
                return -EINVAL;
 
+       mutex_lock(&intel_pstate_driver_lock);
+
+       if (!driver_registered) {
+               mutex_unlock(&intel_pstate_driver_lock);
+               return -EAGAIN;
+       }
+
        mutex_lock(&intel_pstate_limits_lock);
 
        limits->max_sysfs_pct = clamp_t(int, input, 0 , 100);
@@ -1142,6 +1190,8 @@ static ssize_t store_max_perf_pct(struct
 
        intel_pstate_update_policies();
 
+       mutex_unlock(&intel_pstate_driver_lock);
+
        return count;
 }
 
@@ -1155,6 +1205,13 @@ static ssize_t store_min_perf_pct(struct
        if (ret != 1)
                return -EINVAL;
 
+       mutex_lock(&intel_pstate_driver_lock);
+
+       if (!driver_registered) {
+               mutex_unlock(&intel_pstate_driver_lock);
+               return -EAGAIN;
+       }
+
        mutex_lock(&intel_pstate_limits_lock);
 
        limits->min_sysfs_pct = clamp_t(int, input, 0 , 100);
@@ -1170,6 +1227,8 @@ static ssize_t store_min_perf_pct(struct
 
        intel_pstate_update_policies();
 
+       mutex_unlock(&intel_pstate_driver_lock);
+
        return count;
 }
 
@@ -2489,16 +2548,20 @@ hwp_cpu_matched:
 
        intel_pstate_request_control_from_smm();
 
+       intel_pstate_sysfs_expose_params();
+
        rc = cpufreq_register_driver(intel_pstate_driver);
        if (rc)
                goto out;
 
+       mutex_lock(&intel_pstate_driver_lock);
+       driver_registered = true;
+       mutex_unlock(&intel_pstate_driver_lock);
+
        if (intel_pstate_driver == &intel_pstate && !hwp_active &&
            pstate_funcs.get_target_pstate != get_target_pstate_use_cpu_load)
                intel_pstate_debug_expose_params();
 
-       intel_pstate_sysfs_expose_params();
-
        if (hwp_active)
                pr_info("HWP enabled\n");