diff --git a/exosphere/lp0fw/src/car.c b/exosphere/lp0fw/src/car.c
new file mode 100644
index 000000000..bf0a5b780
--- /dev/null
+++ b/exosphere/lp0fw/src/car.c
@@ -0,0 +1,84 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+ 
+#include <stdint.h>
+
+#include "utils.h"
+#include "car.h"
+#include "timer.h"
+#include "lp0.h"
+
+static inline uint32_t get_special_clk_reg(CarDevice dev) {
+    switch (dev) {
+        case CARDEVICE_UARTA: return 0x178;
+        case CARDEVICE_UARTB: return 0x17C;
+        case CARDEVICE_I2C1: return 0x124;
+        case CARDEVICE_I2C5: return 0x128;
+        case CARDEVICE_ACTMON: return 0x3E8;
+        case CARDEVICE_BPMP: return 0;
+        default: reboot();
+    }
+} 
+
+static inline uint32_t get_special_clk_val(CarDevice dev) {
+    switch (dev) {
+        case CARDEVICE_UARTA: return 0;
+        case CARDEVICE_UARTB: return 0;
+        case CARDEVICE_I2C1: return (6 << 29);
+        case CARDEVICE_I2C5: return (6 << 29);
+        case CARDEVICE_ACTMON: return (6 << 29);
+        case CARDEVICE_BPMP: return 0;
+        default: reboot();
+    }
+}
+
+static uint32_t g_clk_reg_offsets[NUM_CAR_BANKS] = {0x010, 0x014, 0x018, 0x360, 0x364, 0x280, 0x298};
+static uint32_t g_rst_reg_offsets[NUM_CAR_BANKS] = {0x004, 0x008, 0x00C, 0x358, 0x35C, 0x28C, 0x2A4}; 
+
+void clk_enable(CarDevice dev) {
+    uint32_t special_reg;
+    if ((special_reg = get_special_clk_reg(dev))) {
+        MAKE_CAR_REG(special_reg) = get_special_clk_val(dev);
+    }
+    MAKE_CAR_REG(g_clk_reg_offsets[dev >> 5]) |= BIT(dev & 0x1F);
+}
+
+void clk_disable(CarDevice dev) {
+    MAKE_CAR_REG(g_clk_reg_offsets[dev >> 5]) &= ~(BIT(dev & 0x1F));
+}
+
+void rst_enable(CarDevice dev) {
+    MAKE_CAR_REG(g_rst_reg_offsets[dev >> 5]) |= BIT(dev & 0x1F);
+}
+
+void rst_disable(CarDevice dev) {
+    MAKE_CAR_REG(g_rst_reg_offsets[dev >> 5]) &= ~(BIT(dev & 0x1F));
+}
+
+void clkrst_enable(CarDevice dev) {
+    clk_enable(dev);
+    rst_disable(dev);
+}
+
+void clkrst_disable(CarDevice dev) {
+    rst_enable(dev);
+    clk_disable(dev);
+}
+
+void clkrst_reboot(CarDevice dev) {
+    clkrst_disable(dev);
+    clkrst_enable(dev);
+}
diff --git a/exosphere/lp0fw/src/car.h b/exosphere/lp0fw/src/car.h
new file mode 100644
index 000000000..c2596b848
--- /dev/null
+++ b/exosphere/lp0fw/src/car.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+ 
+#ifndef EXOSPHERE_WARMBOOT_BIN_CLOCK_AND_RESET_H
+#define EXOSPHERE_WARMBOOT_BIN_CLOCK_AND_RESET_H
+
+#include <stdint.h>
+
+#define CAR_BASE 0x60006000
+
+#define MAKE_CAR_REG(n) MAKE_REG32(CAR_BASE + n)
+
+#define CLK_RST_CONTROLLER_MISC_CLK_ENB_0 MAKE_CAR_REG(0x048)
+#define CLK_RST_CONTROLLER_RST_DEVICES_H_0 MAKE_CAR_REG(0x008)
+#define CLK_RST_CONTROLLER_LVL2_CLK_GATE_OVRD_0 MAKE_CAR_REG(0x3A4)
+#define CLK_RST_CONTROLLER_RST_CPUG_CMPLX_SET_0 MAKE_CAR_REG(0x450)
+#define CLK_RST_CONTROLLER_RST_CPUG_CMPLX_CLR_0 MAKE_CAR_REG(0x454)
+
+#define NUM_CAR_BANKS 7
+
+typedef enum {
+    CARDEVICE_UARTA = 6,
+    CARDEVICE_UARTB = 7,
+    CARDEVICE_I2C1 = 12,
+    CARDEVICE_I2C5 = 47,
+    CARDEVICE_ACTMON = 119,
+    CARDEVICE_BPMP = 1
+} CarDevice;
+
+void clk_enable(CarDevice dev);
+void clk_disable(CarDevice dev);
+void rst_enable(CarDevice dev);
+void rst_disable(CarDevice dev);
+
+void clkrst_enable(CarDevice dev);
+void clkrst_disable(CarDevice dev);
+
+void clkrst_reboot(CarDevice dev);
+
+#endif
diff --git a/exosphere/lp0fw/src/fuse.c b/exosphere/lp0fw/src/fuse.c
new file mode 100644
index 000000000..84a64cfa6
--- /dev/null
+++ b/exosphere/lp0fw/src/fuse.c
@@ -0,0 +1,71 @@
+/*
+ * Copyright (c) 2018 Atmosphère-NX
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+ 
+#include <stdint.h>
+
+#include "utils.h"
+#include "fuse.h"
+#include "car.h"
+#include "pmc.h"
+
+#define NUM_FUSE_BYPASS_ENTRIES 0
+
+bool fuse_check_downgrade_status(void) {
+    /* We aren't going to implement anti-downgrade. */
+    return false;
+}
+
+static fuse_bypass_data_t g_fuse_bypass_entries[NUM_FUSE_BYPASS_ENTRIES] = {
+    /* No entries here. */
+};
+
+void fuse_configure_fuse_bypass(void) {
+    /* Enable fuses in CAR? This seems to affect fuse data visibility. */
+    CLK_RST_CONTROLLER_MISC_CLK_ENB_0 |= 0x10000000;
+    
+    /* Configure bypass/override, only if programming is allowed.  */
+    if (!(FUSE_REGS->FUSE_DIS_PGM & 1)) {
+        /* Enable write access. */
+        FUSE_REGS->FUSE_WRITE_ACCESS = (FUSE_REGS->FUSE_WRITE_ACCESS & ~0x1) | 0x10000;
+        /* Enable fuse bypass config. */
+        FUSE_REGS->FUSE_FUSEBYPASS = 1;
+        
+        /* Override fuses. */
+        for (size_t i = 0; i < NUM_FUSE_BYPASS_ENTRIES; i++) {
+            MAKE_FUSE_REG(g_fuse_bypass_entries[i].offset) = g_fuse_bypass_entries[i].value;
+        }
+        
+        /* Disable fuse write access. */
+        FUSE_REGS->FUSE_WRITE_ACCESS |= 1;
+        
+        /* Enable fuse bypass config. */
+        /* I think this is a bug, and Nintendo meant to write 0 here? */
+        FUSE_REGS->FUSE_FUSEBYPASS = 1;
+        
+        /* This...clears the disable programming bit(?). */
+        /* I have no idea why this happens. What? */
+        /* This is probably also either a bug or does nothing. */
+        /* Is this bit even clearable? */
+        FUSE_REGS->FUSE_DIS_PGM &= 0xFFFFFFFE;
+        
+        /* Restore saved private key disable bit. */
+        FUSE_REGS->FUSE_PRIVATEKEYDISABLE |= (APBDEV_PMC_SECURE_SCRATCH21_0 & 0x10);
+        
+        /* Lock private key disable secure scratch. */
+        APBDEV_PMC_SEC_DISABLE2_0 |= 0x4000000;
+    }
+    
+}
diff --git a/exosphere/lp0fw/src/fuse.h b/exosphere/lp0fw/src/fuse.h
index b07e8b9d5..39706bd89 100644
--- a/exosphere/lp0fw/src/fuse.h
+++ b/exosphere/lp0fw/src/fuse.h
@@ -186,4 +186,15 @@ typedef struct {
 #define FUSE_REGS       ((volatile fuse_registers_t *)(0x7000F800))
 #define FUSE_CHIP_REGS  ((volatile fuse_chip_registers_t *)(0x7000F900))
 
+#define MAKE_FUSE_REG(n) MAKE_REG32(0x7000F800 + n)
+
+typedef struct {
+    uint32_t offset;
+    uint32_t value;
+} fuse_bypass_data_t;
+
+bool fuse_check_downgrade_status(void);
+
+void fuse_configure_fuse_bypass(void);
+
 #endif
diff --git a/exosphere/lp0fw/src/lp0.c b/exosphere/lp0fw/src/lp0.c
index fd6525a41..dcb68aa4d 100644
--- a/exosphere/lp0fw/src/lp0.c
+++ b/exosphere/lp0fw/src/lp0.c
@@ -19,6 +19,7 @@
 #include "mc.h"
 #include "pmc.h"
 #include "misc.h"
+#include "fuse.h"
 #include "timer.h"
 
 void reboot(void) {
@@ -30,19 +31,40 @@ void reboot(void) {
 }
 
 void lp0_entry_main(warmboot_metadata_t *meta) {
+    const uint32_t target_firmware = meta->target_firmware;
     /* Before doing anything else, ensure some sanity. */
-    if (meta->magic != WARMBOOT_MAGIC || meta->target_firmware > ATMOSPHERE_TARGET_FIRMWARE_MAX) {
+    if (meta->magic != WARMBOOT_MAGIC || target_firmware > ATMOSPHERE_TARGET_FIRMWARE_MAX) {
         reboot();
     }
     
     /* [4.0.0+] First thing warmboot does is disable BPMP access to memory. */
-    if (meta->target_firmware >= ATMOSPHERE_TARGET_FIRMWARE_400)  {
+    if (target_firmware >= ATMOSPHERE_TARGET_FIRMWARE_400)  {
         disable_bpmp_access_to_dram();
     }
     
     /* Configure debugging depending on FUSE_PRODUCTION_MODE */
     configure_device_dbg_settings();
     
+    /* Check for downgrade. */
+    /* NOTE: We implemented this as "return false" */
+    if (fuse_check_downgrade_status()) {
+        reboot();
+    }
+    
+    if (target_firmware >= ATMOSPHERE_TARGET_FIRMWARE_300) {
+        /* Nintendo's firmware checks APBDEV_PMC_SECURE_SCRATCH32_0 against a per-warmboot binary value here. */
+        /* We won't bother with that. */
+        if (false /* APBDEV_PMC_SECURE_SCRATCH32_0 == WARMBOOT_MAGIC_NUMBER */) {
+            reboot();
+        }
+    }
+    
+    /* TODO: Check that we're running at the correct physical address. */
+    
+    /* Setup fuses, disable bypass. */
+    fuse_configure_fuse_bypass();
+    
+    
     /* TODO: stuff */
 
     while (true) { /* TODO: Halt BPMP */ }
diff --git a/exosphere/lp0fw/src/lp0.h b/exosphere/lp0fw/src/lp0.h
index 90cdb6850..04787f0ed 100644
--- a/exosphere/lp0fw/src/lp0.h
+++ b/exosphere/lp0fw/src/lp0.h
@@ -30,6 +30,6 @@ typedef struct {
 
 void lp0_entry_main(warmboot_metadata_t *meta);
 
-void reboot(void);
+void __attribute__((noreturn)) reboot(void);
 
 #endif
diff --git a/exosphere/lp0fw/src/misc.h b/exosphere/lp0fw/src/misc.h
index 6d34e075f..4c94002c2 100644
--- a/exosphere/lp0fw/src/misc.h
+++ b/exosphere/lp0fw/src/misc.h
@@ -19,6 +19,8 @@
 
 #include <stdint.h>
 
+#include "utils.h"
+
 #define MISC_BASE  (0x70000000)
 
 #define MAKE_MISC_REG(n) MAKE_REG32(MISC_BASE + n)
diff --git a/exosphere/lp0fw/src/pmc.h b/exosphere/lp0fw/src/pmc.h
index 9025fbd33..982caf444 100644
--- a/exosphere/lp0fw/src/pmc.h
+++ b/exosphere/lp0fw/src/pmc.h
@@ -38,8 +38,12 @@
 #define APBDEV_PMC_SCRATCH18_0       MAKE_PMC_REG(0x098)
 
 #define APBDEV_PMC_STICKY_BITS_0     MAKE_PMC_REG(0x2C0)
+#define APBDEV_PMC_SEC_DISABLE2_0    MAKE_PMC_REG(0x2C4)
 #define APBDEV_PMC_WEAK_BIAS_0       MAKE_PMC_REG(0x2C8)
 
+#define APBDEV_PMC_SECURE_SCRATCH21_0 MAKE_PMC_REG(0x334)
+#define APBDEV_PMC_SECURE_SCRATCH32_0 MAKE_PMC_REG(0x360)
+
 #define APBDEV_PMC_IO_DPD3_REQ_0     MAKE_PMC_REG(0x45C)
 #define APBDEV_PMC_IO_DPD3_STATUS_0  MAKE_PMC_REG(0x460)