diff --git a/exosphere/src/car.c b/exosphere/src/car.c
index 689f2d888..a9e69e72b 100644
--- a/exosphere/src/car.c
+++ b/exosphere/src/car.c
@@ -34,19 +34,19 @@ void clk_enable(car_device_t dev) {
     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));
+    MAKE_CAR_REG(g_clk_reg_offsets[dev >> 5]) |= BIT(dev & 0x1F);
 }
 
 void clk_disable(car_device_t dev) {
-    MAKE_CAR_REG(g_clk_reg_offsets[dev >> 5] + 0x004) |= BIT((dev & 0x1F));
+    MAKE_CAR_REG(g_clk_reg_offsets[dev >> 5] + 0x004) |= BIT(dev & 0x1F);
 }
 
 void rst_enable(car_device_t dev) {
-    MAKE_CAR_REG(g_rst_reg_offsets[dev >> 5]) |= BIT((dev & 0x1F));
+    MAKE_CAR_REG(g_rst_reg_offsets[dev >> 5]) |= BIT(dev & 0x1F);
 }
 
 void rst_disable(car_device_t dev) {
-    MAKE_CAR_REG(g_rst_reg_offsets[dev >> 5] + 0x004) |= BIT((dev & 0x1F));
+    MAKE_CAR_REG(g_rst_reg_offsets[dev >> 5] + 0x004) |= BIT(dev & 0x1F);
 }
 
 
diff --git a/exosphere/src/fuse.c b/exosphere/src/fuse.c
index a88b13490..e3cf5ba74 100644
--- a/exosphere/src/fuse.c
+++ b/exosphere/src/fuse.c
@@ -5,6 +5,7 @@
 #include "utils.h"
 #include "timers.h"
 
+#include "masterkey.h"
 /* Prototypes for internal commands. */
 void fuse_make_regs_visible(void);
 
@@ -178,18 +179,23 @@ uint32_t fuse_get_dram_id(void) {
 
 /* Derive the Hardware Type using values in the shadow cache */
 uint32_t fuse_get_hardware_type(void) {
+    /* This function is very different between 4.x and < 4.x */
     uint32_t hardware_type = ((FUSE_CHIP_REGS->FUSE_RESERVED_ODM[4] >> 7) & 2) | ((FUSE_CHIP_REGS->FUSE_RESERVED_ODM[4] >> 2) & 1);
-    if (hardware_type) {
-        if (hardware_type == 1) {
+    
+    if (mkey_get_revision() >= MASTERKEY_REVISION_400_CURRENT) {
+        static const uint32_t types[] = {0,1,4,3};
+
+        hardware_type |= ((FUSE_CHIP_REGS->FUSE_RESERVED_ODM[4] >> 14) & 0x3C) - 1;
+        return hardware_type > 3 ? 4 : types[hardware_type];
+    } else {
+        if (hardware_type >= 1) {
+            return hardware_type > 2 ? 3 : hardware_type - 1; 
+        } else if ((FUSE_CHIP_REGS->FUSE_SPARE_BIT[9] & 1) == 0) {
             return 0;
+        } else {
+            return 3;
         }
-        if (hardware_type == 2) {
-            return 1;
-        }
-    } else if ((FUSE_CHIP_REGS->FUSE_SPARE_BIT[9] & 1) == 0) {
-        return 0;
     }
-    return 3;
 }
 
 /* Derive the Retail Type using values in the shadow cache */
diff --git a/exosphere/src/misc.h b/exosphere/src/misc.h
index de19c152b..08950aeb7 100644
--- a/exosphere/src/misc.h
+++ b/exosphere/src/misc.h
@@ -16,4 +16,7 @@
 #define APB_MISC_SECURE_REGS_APB_SLAVE_SECURITY_ENABLE_REG1_0 MAKE_MISC_REG(0x0C04)
 #define APB_MISC_SECURE_REGS_APB_SLAVE_SECURITY_ENABLE_REG2_0 MAKE_MISC_REG(0x0C08)
 
+#define PINMUX_AUX_GEN1_I2C_SCL_0 MAKE_MISC_REG(0x30BC)
+#define PINMUX_AUX_GEN1_I2C_SDA_0 MAKE_MISC_REG(0x30C0)
+
 #endif
diff --git a/exosphere/src/warmboot_main.c b/exosphere/src/warmboot_main.c
index d21b0cd9e..1b3a3ea72 100644
--- a/exosphere/src/warmboot_main.c
+++ b/exosphere/src/warmboot_main.c
@@ -10,6 +10,9 @@
 
 #include "se.h"
 #include "mc.h"
+#include "car.h"
+#include "i2c.h"
+#include "misc.h"
 #include "interrupt.h"
 
 void __attribute__((noreturn)) warmboot_main(void) {
@@ -42,7 +45,16 @@ void __attribute__((noreturn)) warmboot_main(void) {
         /* Make PMC (2.x+), MC (4.x+) registers secure-only */
         secure_additional_devices();
 
-        /* TODO: car+clkreset stuff, some other mmio (?) */
+        if (mkey_get_revision() < MASTERKEY_REVISION_400_CURRENT || configitem_get_hardware_type() == 0) {
+            /* Enable input to I2C1 */
+            PINMUX_AUX_GEN1_I2C_SCL_0 = 0x40;
+            PINMUX_AUX_GEN1_I2C_SDA_0 = 0x40;
+
+            clkrst_enable(CARDEVICE_I2C1);
+            i2c_init(0);
+            i2c_clear_ti_charger_bit_7();
+            clkrst_disable(CARDEVICE_I2C1);
+        }
 
         if (mkey_get_revision() >= MASTERKEY_REVISION_400_CURRENT) {
             setup_4x_mmio(); /* TODO */