flo: Use cpufreq limit driver to limit frequencies

Previously, the PowerHAL was using the standard scaling_[min|max]_freq
interfaces to limit CPU maximum and minimum frequencies during
low power mode in order to conserve power.

However, the CPU cores on flo lose their min/max frequencies on
every hotplug, rendering this interface useless. Switch to the
cpufreq_limit driver to fix this issue.

This switch also allows us to remove all the unneeded uevent code,
simplifying the code.

Change-Id: I478bcb745046dde0caf226e46fa1e875f7fafc2c

2 files changed, 10 insertions, 127 deletions

diff --git a/init.flo.rc b/init.flo.rc
index ac3fdbc..4a72ad6 100644
--- a/init.flo.rc
+++ b/init.flo.rc
@@ -116,6 +116,10 @@ on boot
     write /proc/sys/net/core/rmem_max  2097152
     write /proc/sys/net/core/wmem_max  2097152
 
+    # CPUFreq limit
+    chown system system /sys/kernel/cpufreq_limit/limited_max_freq
+    chown system system /sys/kernel/cpufreq_limit/limited_min_freq
+
 # msm specific files that need to be created on /data
 on post-fs-data
     chown system system /dev/wcnss_wlan
diff --git a/power/power_flo.c b/power/power_flo.c
index c4112af..dad9491 100644
--- a/power/power_flo.c
+++ b/power/power_flo.c
@@ -21,7 +21,6 @@
 #include <sys/un.h>
 #include <fcntl.h>
 #include <dlfcn.h>
-#include <cutils/uevent.h>
 #include <errno.h>
 #include <sys/poll.h>
 #include <pthread.h>
@@ -41,33 +40,17 @@
 #define MAX_LENGTH         50
 #define BOOST_SOCKET       "/dev/socket/pb"
 
-#define UEVENT_MSG_LEN 2048
-#define TOTAL_CPUS 4
-#define RETRY_TIME_CHANGING_FREQ 20
-#define SLEEP_USEC_BETWN_RETRY 200
 #define LOW_POWER_MAX_FREQ 1026000
 #define LOW_POWER_MIN_FREQ 384000
 #define NORMAL_MAX_FREQ 1512000
-#define UEVENT_STRING "online@/devices/system/cpu/"
+
+#define MAX_FREQ_LIMIT_PATH "/sys/kernel/cpufreq_limit/limited_max_freq"
+#define MIN_FREQ_LIMIT_PATH "/sys/kernel/cpufreq_limit/limited_min_freq"
 
 static int client_sockfd;
 static struct sockaddr_un client_addr;
 static int last_state = -1;
 
-static struct pollfd pfd;
-static char *cpu_path_min[] = {
-    "/sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq",
-    "/sys/devices/system/cpu/cpu1/cpufreq/scaling_min_freq",
-    "/sys/devices/system/cpu/cpu2/cpufreq/scaling_min_freq",
-    "/sys/devices/system/cpu/cpu3/cpufreq/scaling_min_freq",
-};
-static char *cpu_path_max[] = {
-    "/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq",
-    "/sys/devices/system/cpu/cpu1/cpufreq/scaling_max_freq",
-    "/sys/devices/system/cpu/cpu2/cpufreq/scaling_max_freq",
-    "/sys/devices/system/cpu/cpu3/cpufreq/scaling_max_freq",
-};
-static bool freq_set[TOTAL_CPUS];
 static bool low_power_mode = false;
 static pthread_mutex_t low_power_mode_lock = PTHREAD_MUTEX_INITIALIZER;
 
@@ -108,104 +91,10 @@ static int sysfs_write(const char *path, char *s)
     return 0;
 }
 
-static int uevent_event()
-{
-    char msg[UEVENT_MSG_LEN];
-    char *cp;
-    int n, cpu, ret, retry = RETRY_TIME_CHANGING_FREQ;
-
-    n = recv(pfd.fd, msg, UEVENT_MSG_LEN, MSG_DONTWAIT);
-    if (n <= 0) {
-        return -1;
-    }
-    if (n >= UEVENT_MSG_LEN) {   /* overflow -- discard */
-        return -1;
-    }
-
-    cp = msg;
-
-    if (strstr(cp, UEVENT_STRING)) {
-        n = strlen(cp);
-        errno = 0;
-        cpu = strtol(cp + n - 1, NULL, 10);
-
-        if (errno == EINVAL || errno == ERANGE || cpu < 0 || cpu >= TOTAL_CPUS) {
-            return -1;
-        }
-
-        pthread_mutex_lock(&low_power_mode_lock);
-        if (low_power_mode && !freq_set[cpu]) {
-            while (retry) {
-                sysfs_write(cpu_path_min[cpu], LOW_POWER_MIN_FREQ);
-                ret = sysfs_write(cpu_path_max[cpu], LOW_POWER_MAX_FREQ);
-                if (!ret) {
-                    freq_set[cpu] = true;
-                    break;
-                }
-                usleep(SLEEP_USEC_BETWN_RETRY);
-                retry--;
-           }
-        } else if (!low_power_mode && freq_set[cpu]) {
-             while (retry) {
-                  ret = sysfs_write(cpu_path_max[cpu], NORMAL_MAX_FREQ);
-                  if (!ret) {
-                      freq_set[cpu] = false;
-                      break;
-                  }
-                  usleep(SLEEP_USEC_BETWN_RETRY);
-                  retry--;
-             }
-        }
-        pthread_mutex_unlock(&low_power_mode_lock);
-    }
-    return 0;
-}
-
-void *thread_uevent(__attribute__((unused)) void *x)
-{
-    while (1) {
-        int nevents, ret;
-
-        nevents = poll(&pfd, 1, -1);
-
-        if (nevents == -1) {
-            if (errno == EINTR)
-                continue;
-            ALOGE("powerhal: thread_uevent: poll_wait failed\n");
-            break;
-        }
-        ret = uevent_event();
-        if (ret < 0)
-            ALOGE("Error processing the uevent event");
-    }
-    return NULL;
-}
-
-static void uevent_init()
-{
-    struct sockaddr_nl client;
-    pthread_t tid;
-    pfd.fd = socket(PF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
-
-    if (pfd.fd < 0) {
-        ALOGE("%s: failed to open: %s", __func__, strerror(errno));
-        return;
-    }
-    memset(&client, 0, sizeof(struct sockaddr_nl));
-    pthread_create(&tid, NULL, thread_uevent, NULL);
-    client.nl_family = AF_NETLINK;
-    client.nl_pid = tid;
-    client.nl_groups = -1;
-    pfd.events = POLLIN;
-    bind(pfd.fd, (void *)&client, sizeof(struct sockaddr_nl));
-    return;
-}
-
 static void power_init(__attribute__((unused)) struct power_module *module)
 {
     ALOGI("%s", __func__);
     socket_init();
-    uevent_init();
 }
 
 static void sync_thread(int off)
@@ -346,21 +235,11 @@ static void power_hint( __attribute__((unused)) struct power_module *module,
             pthread_mutex_lock(&low_power_mode_lock);
             if (data) {
                 low_power_mode = true;
-                for (cpu = 0; cpu < TOTAL_CPUS; cpu++) {
-                    sysfs_write(cpu_path_min[cpu], LOW_POWER_MIN_FREQ);
-                    ret = sysfs_write(cpu_path_max[cpu], LOW_POWER_MAX_FREQ);
-                    if (!ret) {
-                        freq_set[cpu] = true;
-                    }
-                }
+                sysfs_write(MIN_FREQ_LIMIT_PATH, LOW_POWER_MIN_FREQ);
+                sysfs_write(MAX_FREQ_LIMIT_PATH, LOW_POWER_MAX_FREQ);
             } else {
                 low_power_mode = false;
-                for (cpu = 0; cpu < TOTAL_CPUS; cpu++) {
-                    ret = sysfs_write(cpu_path_max[cpu], NORMAL_MAX_FREQ);
-                    if (!ret) {
-                        freq_set[cpu] = false;
-                    }
-                }
+                sysfs_write(MAX_FREQ_LIMIT_PATH, NORMAL_MAX_FREQ);
             }
             pthread_mutex_unlock(&low_power_mode_lock);
             break;