drivers: tegra: Disallow cluster switch if fuse set

Prevent any cluster switches if the disable slow cluster fuse is set.
Not doing so will hang the system.

Bug 1648455

Change-Id: Icb57ff63693a1f15b7e4a84c617cc7fe1c595747
Signed-off-by: Sai Gurrappadi <sgurrappadi@nvidia.com>
Reviewed-on: http://git-master/r/752805
GVS: Gerrit_Virtual_Submit
Tested-by: Hayden Du <haydend@nvidia.com>
Reviewed-by: Sivaram Nair <sivaramn@nvidia.com>
Reviewed-by: Hayden Du <haydend@nvidia.com>

diff --git a/drivers/platform/tegra/cluster-control.c b/drivers/platform/tegra/cluster-control.c
index a722d15578c9f0390a5d27916bfb14b3632aeab2..7dbe48bc5bb490ef40b48250cf14ab713c90b789 100644 (file)
--- a/drivers/platform/tegra/cluster-control.c
+++ b/drivers/platform/tegra/cluster-control.c
@@ -23,6 +23,7 @@
 #include <linux/notifier.h>
 #include <linux/stop_machine.h>
 #include <linux/tegra_cluster_control.h>
+#include <linux/tegra-fuse.h>
 #include <soc/tegra/tegra_bpmp.h>
 #include <asm/psci.h>
 #include <asm/smp_plat.h>
@@ -38,6 +39,9 @@
 #define PSCI_RET_EINVAL                 -2
 #define PSCI_RET_EPERM                  -3
 
+#define SKU_DIRECT_CONFIG              0x1f4
+#define DISABLE_SLOW_CLUSTER_BIT       5
+
 static DEFINE_MUTEX(cluster_switch_lock);
 static unsigned long pg_core_arg, pg_cluster_arg;
 
@@ -55,6 +59,8 @@ static struct psci_power_state cluster_pg __initdata = {
 
 static DEFINE_PER_CPU(struct cpu_stop_work, shutdown_core_work);
 
+static u32 slow_cluster_disabled = 1;
+
 static int shutdown_core(void *info)
 {
        uintptr_t target_cluster = (uintptr_t)info;
@@ -169,9 +175,12 @@ static void switch_cluster(enum cluster val)
 int tegra_cluster_control(unsigned int us, unsigned int flags)
 {
        int cluster_flag = flags & TEGRA_POWER_CLUSTER_MASK;
+       enum cluster current_cluster = is_lp_cluster();
+
+       /* HW has disabled the slow cluster. Can't be using it...*/
+       BUG_ON(slow_cluster_disabled && current_cluster);
 
        if (cluster_flag == TEGRA_POWER_CLUSTER_G) {
-               enum cluster current_cluster = is_lp_cluster();
                trace_nvcpu_clusterswitch(NVPOWER_CPU_CLUSTER_START,
                                          current_cluster,
                                          FAST_CLUSTER);
@@ -180,7 +189,9 @@ int tegra_cluster_control(unsigned int us, unsigned int flags)
                                          current_cluster,
                                          FAST_CLUSTER);
        } else if (cluster_flag == TEGRA_POWER_CLUSTER_LP) {
-               enum cluster current_cluster = is_lp_cluster();
+               if (slow_cluster_disabled)
+                       return -EINVAL;
+
                trace_nvcpu_clusterswitch(NVPOWER_CPU_CLUSTER_START,
                                          current_cluster,
                                          SLOW_CLUSTER);
@@ -193,13 +204,42 @@ int tegra_cluster_control(unsigned int us, unsigned int flags)
        return 0;
 }
 
+#ifdef CONFIG_DEBUG_FS
+static int slow_cluster_enabled_get(void *data, u64 *val)
+{
+       *val = !slow_cluster_disabled;
+       return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(slow_cluster_enabled_ops, slow_cluster_enabled_get,
+                       NULL, "%llu\n");
+
+static void setup_debugfs(void)
+{
+       struct dentry *rootdir;
+
+       rootdir = debugfs_create_dir("tegra_cluster", NULL);
+       if (rootdir)
+               debugfs_create_file("slow_cluster_enabled", S_IRUGO,
+                               rootdir, NULL, &slow_cluster_enabled_ops);
+}
+#else
+static void setup_debugfs(void) {}
+#endif
+
 static int __init tegra210_cluster_control_init(void)
 {
        pg_core_arg = psci_power_state_pack(core_pg);
        pg_cluster_arg = psci_power_state_pack(cluster_pg);
 
-       pr_info("Tegra210 cluster control initialized\n");
+       slow_cluster_disabled = tegra_fuse_readl(SKU_DIRECT_CONFIG);
+       slow_cluster_disabled >>= DISABLE_SLOW_CLUSTER_BIT;
+       slow_cluster_disabled &= 0x1;
+
+       setup_debugfs();
 
+       pr_info("Tegra210 cluster control initialized. LP disabled=%d\n",
+                       slow_cluster_disabled);
        return 0;
 }