diff --git a/src/sio/sio_82091aa.c b/src/sio/sio_82091aa.c
index 346d2d435..cbe89c682 100644
--- a/src/sio/sio_82091aa.c
+++ b/src/sio/sio_82091aa.c
@@ -209,9 +209,9 @@ i82091aa_write(uint16_t port, uint8_t val, void *priv)
 uint8_t
 i82091aa_read(uint16_t port, void *priv)
 {
-    i82091aa_t *dev = (i82091aa_t *) priv;
-    uint8_t     ret = 0xff;
-    uint8_t     index;
+    const i82091aa_t *dev = (i82091aa_t *) priv;
+    uint8_t           ret = 0xff;
+    uint8_t           index;
 
     index = (port & 1) ? 0 : 1;
 
diff --git a/src/sio/sio_acc3221.c b/src/sio/sio_acc3221.c
index 10250d602..275d9ae2e 100644
--- a/src/sio/sio_acc3221.c
+++ b/src/sio/sio_acc3221.c
@@ -416,7 +416,7 @@ acc3221_write(uint16_t addr, uint8_t val, void *priv)
 static uint8_t
 acc3221_read(uint16_t addr, void *priv)
 {
-    acc3221_t *dev = (acc3221_t *) priv;
+    const acc3221_t *dev = (acc3221_t *) priv;
 
     if (!(addr & 1))
         return dev->reg_idx;
diff --git a/src/sio/sio_ali5123.c b/src/sio/sio_ali5123.c
index 25fb1aa65..78c585c11 100644
--- a/src/sio/sio_ali5123.c
+++ b/src/sio/sio_ali5123.c
@@ -428,10 +428,10 @@ ali5123_write(uint16_t port, uint8_t val, void *priv)
 static uint8_t
 ali5123_read(uint16_t port, void *priv)
 {
-    ali5123_t *dev   = (ali5123_t *) priv;
-    uint8_t    index = (port & 1) ? 0 : 1;
-    uint8_t    ret   = 0xff;
-    uint8_t    cur_ld;
+    const ali5123_t *dev   = (ali5123_t *) priv;
+    uint8_t          index = (port & 1) ? 0 : 1;
+    uint8_t          ret   = 0xff;
+    uint8_t          cur_ld;
 
     if (dev->locked) {
         if (index)
diff --git a/src/sio/sio_detect.c b/src/sio/sio_detect.c
index 01c41224a..38faf3c2c 100644
--- a/src/sio/sio_detect.c
+++ b/src/sio/sio_detect.c
@@ -47,7 +47,7 @@ sio_detect_write(uint16_t port, uint8_t val, void *priv)
 static uint8_t
 sio_detect_read(uint16_t port, void *priv)
 {
-    sio_detect_t *dev = (sio_detect_t *) priv;
+    const sio_detect_t *dev = (sio_detect_t *) priv;
 
     pclog("sio_detect_read : port=%04x = %02X\n", port, dev->regs[port & 1]);
 
diff --git a/src/sio/sio_f82c710.c b/src/sio/sio_f82c710.c
index 07157dd0b..d4afb11da 100644
--- a/src/sio/sio_f82c710.c
+++ b/src/sio/sio_f82c710.c
@@ -228,8 +228,8 @@ f82c606_update_ports(upc_t *dev, int set)
 static uint8_t
 f82c710_config_read(uint16_t port, void *priv)
 {
-    upc_t  *dev  = (upc_t *) priv;
-    uint8_t temp = 0xff;
+    const upc_t  *dev  = (upc_t *) priv;
+    uint8_t       temp = 0xff;
 
     if (dev->configuration_mode) {
         if (port == dev->cri_addr) {
diff --git a/src/sio/sio_fdc37c669.c b/src/sio/sio_fdc37c669.c
index 3a1bcf5af..b2c8933c6 100644
--- a/src/sio/sio_fdc37c669.c
+++ b/src/sio/sio_fdc37c669.c
@@ -231,9 +231,9 @@ fdc37c669_write(uint16_t port, uint8_t val, void *priv)
 static uint8_t
 fdc37c669_read(uint16_t port, void *priv)
 {
-    fdc37c669_t *dev   = (fdc37c669_t *) priv;
-    uint8_t      index = (port & 1) ? 0 : 1;
-    uint8_t      ret   = 0xff;
+    const fdc37c669_t *dev   = (fdc37c669_t *) priv;
+    uint8_t            index = (port & 1) ? 0 : 1;
+    uint8_t            ret   = 0xff;
 
     if (dev->locked) {
         if (index)
diff --git a/src/sio/sio_fdc37c67x.c b/src/sio/sio_fdc37c67x.c
index 3cfa5a38d..871f3b1c8 100644
--- a/src/sio/sio_fdc37c67x.c
+++ b/src/sio/sio_fdc37c67x.c
@@ -71,7 +71,7 @@ make_port(fdc37c67x_t *dev, uint8_t ld)
 static uint8_t
 fdc37c67x_auxio_read(UNUSED(uint16_t port), void *priv)
 {
-    fdc37c67x_t *dev = (fdc37c67x_t *) priv;
+    const fdc37c67x_t *dev = (fdc37c67x_t *) priv;
 
     return dev->auxio_reg;
 }
@@ -87,8 +87,8 @@ fdc37c67x_auxio_write(UNUSED(uint16_t port), uint8_t val, void *priv)
 static uint8_t
 fdc37c67x_gpio_read(uint16_t port, void *priv)
 {
-    fdc37c67x_t *dev = (fdc37c67x_t *) priv;
-    uint8_t      ret = 0xff;
+    const fdc37c67x_t *dev = (fdc37c67x_t *) priv;
+    uint8_t            ret = 0xff;
 
     ret = dev->gpio_regs[port & 1];
 
@@ -316,6 +316,7 @@ fdc37c67x_write(uint16_t port, uint8_t val, void *priv)
             case 0x26:
             case 0x27:
                 fdc37c67x_sio_handler(dev);
+                break;
 
             default:
                 break;
diff --git a/src/sio/sio_fdc37c6xx.c b/src/sio/sio_fdc37c6xx.c
index 24bb6bb09..23fcd2fb3 100644
--- a/src/sio/sio_fdc37c6xx.c
+++ b/src/sio/sio_fdc37c6xx.c
@@ -228,8 +228,8 @@ fdc37c6xx_write(uint16_t port, uint8_t val, void *priv)
 static uint8_t
 fdc37c6xx_read(uint16_t port, void *priv)
 {
-    fdc37c6xx_t *dev = (fdc37c6xx_t *) priv;
-    uint8_t      ret = 0xff;
+    const fdc37c6xx_t *dev = (fdc37c6xx_t *) priv;
+    uint8_t            ret = 0xff;
 
     if (dev->tries == 2) {
         if (port == 0x3f1)
diff --git a/src/sio/sio_fdc37c93x.c b/src/sio/sio_fdc37c93x.c
index 0330297fb..4acbfeff5 100644
--- a/src/sio/sio_fdc37c93x.c
+++ b/src/sio/sio_fdc37c93x.c
@@ -93,7 +93,7 @@ make_port_sec(fdc37c93x_t *dev, uint8_t ld)
 static uint8_t
 fdc37c93x_auxio_read(UNUSED(uint16_t port), void *priv)
 {
-    fdc37c93x_t *dev = (fdc37c93x_t *) priv;
+    const fdc37c93x_t *dev = (fdc37c93x_t *) priv;
 
     return dev->auxio_reg;
 }
@@ -109,8 +109,8 @@ fdc37c93x_auxio_write(UNUSED(uint16_t port), uint8_t val, void *priv)
 static uint8_t
 fdc37c93x_gpio_read(uint16_t port, void *priv)
 {
-    fdc37c93x_t *dev = (fdc37c93x_t *) priv;
-    uint8_t      ret = 0xff;
+    const fdc37c93x_t *dev = (fdc37c93x_t *) priv;
+    uint8_t            ret = 0xff;
 
     ret = dev->gpio_regs[port & 1];
 
@@ -257,8 +257,8 @@ fdc37c93x_gpio_handler(fdc37c93x_t *dev)
 static uint8_t
 fdc37c93x_access_bus_read(uint16_t port, void *priv)
 {
-    access_bus_t *dev = (access_bus_t *) priv;
-    uint8_t       ret = 0xff;
+    const access_bus_t *dev = (access_bus_t *) priv;
+    uint8_t             ret = 0xff;
 
     switch (port & 3) {
         case 0:
diff --git a/src/sio/sio_fdc37m60x.c b/src/sio/sio_fdc37m60x.c
index 190e65453..38a163538 100644
--- a/src/sio/sio_fdc37m60x.c
+++ b/src/sio/sio_fdc37m60x.c
@@ -163,8 +163,8 @@ fdc37m60x_write(uint16_t addr, uint8_t val, void *priv)
 static uint8_t
 fdc37m60x_read(uint16_t addr, void *priv)
 {
-    fdc37m60x_t *dev = (fdc37m60x_t *) priv;
-    uint8_t      ret = 0xff;
+    const fdc37m60x_t *dev = (fdc37m60x_t *) priv;
+    uint8_t            ret = 0xff;
 
     if (addr & 1)
         ret = (INDEX >= 0x30) ? dev->device_regs[CURRENT_LOGICAL_DEVICE][INDEX] : dev->regs[INDEX];
diff --git a/src/sio/sio_it8661f.c b/src/sio/sio_it8661f.c
index 5e5ccb655..5367ffedf 100644
--- a/src/sio/sio_it8661f.c
+++ b/src/sio/sio_it8661f.c
@@ -272,7 +272,7 @@ it8661f_write(uint16_t addr, uint8_t val, void *priv)
 static uint8_t
 it8661f_read(uint16_t addr, void *priv)
 {
-    it8661f_t *dev = (it8661f_t *) priv;
+    const it8661f_t *dev = (it8661f_t *) priv;
 
     it8661_log("IT8661F:\n", addr, dev->regs[dev->index]);
     return (addr == 0xa79) ? dev->regs[dev->index] : 0xff;
diff --git a/src/sio/sio_pc87306.c b/src/sio/sio_pc87306.c
index 63ab1777c..f725e11fc 100644
--- a/src/sio/sio_pc87306.c
+++ b/src/sio/sio_pc87306.c
@@ -57,7 +57,7 @@ pc87306_gpio_write(uint16_t port, uint8_t val, void *priv)
 uint8_t
 pc87306_gpio_read(uint16_t port, void *priv)
 {
-    pc87306_t *dev = (pc87306_t *) priv;
+    const pc87306_t *dev = (pc87306_t *) priv;
 
     return dev->gpio[port & 1];
 }
diff --git a/src/sio/sio_pc87307.c b/src/sio/sio_pc87307.c
index e66467d62..63e19c03d 100644
--- a/src/sio/sio_pc87307.c
+++ b/src/sio/sio_pc87307.c
@@ -67,11 +67,11 @@ pc87307_gpio_write(uint16_t port, uint8_t val, void *priv)
 uint8_t
 pc87307_gpio_read(uint16_t port, void *priv)
 {
-    pc87307_t *dev  = (pc87307_t *) priv;
-    uint8_t    pins = 0xff;
-    uint8_t    bank = ((port & 0xfffc) == dev->gpio_base2);
-    uint8_t    mask;
-    uint8_t    ret  = dev->gpio[bank][port & 0x0003];
+    const pc87307_t *dev  = (pc87307_t *) priv;
+    uint8_t          pins = 0xff;
+    uint8_t          bank = ((port & 0xfffc) == dev->gpio_base2);
+    uint8_t          mask;
+    uint8_t          ret  = dev->gpio[bank][port & 0x0003];
 
     switch (port & 0x0003) {
         case 0x0000:
@@ -139,7 +139,7 @@ pc87307_pm_write(uint16_t port, uint8_t val, void *priv)
 uint8_t
 pc87307_pm_read(uint16_t port, void *priv)
 {
-    pc87307_t *dev = (pc87307_t *) priv;
+    const pc87307_t *dev = (pc87307_t *) priv;
 
     if (port & 1)
         return dev->pm[dev->pm_idx];
@@ -456,9 +456,9 @@ pc87307_write(uint16_t port, uint8_t val, void *priv)
 uint8_t
 pc87307_read(uint16_t port, void *priv)
 {
-    pc87307_t *dev = (pc87307_t *) priv;
-    uint8_t    ret = 0xff;
-    uint8_t    index;
+    const pc87307_t *dev = (pc87307_t *) priv;
+    uint8_t          ret = 0xff;
+    uint8_t          index;
 
     index = (port & 1) ? 0 : 1;
 
diff --git a/src/sio/sio_pc87309.c b/src/sio/sio_pc87309.c
index edd1fb0b8..d10cb3e0b 100644
--- a/src/sio/sio_pc87309.c
+++ b/src/sio/sio_pc87309.c
@@ -77,7 +77,7 @@ pc87309_pm_write(uint16_t port, uint8_t val, void *priv)
 uint8_t
 pc87309_pm_read(uint16_t port, void *priv)
 {
-    pc87309_t *dev = (pc87309_t *) priv;
+    const pc87309_t *dev = (pc87309_t *) priv;
 
     if (port & 1)
         return dev->pm[dev->pm_idx];
@@ -351,9 +351,9 @@ pc87309_write(uint16_t port, uint8_t val, void *priv)
 uint8_t
 pc87309_read(uint16_t port, void *priv)
 {
-    pc87309_t *dev = (pc87309_t *) priv;
-    uint8_t    ret = 0xff;
-    uint8_t    index;
+    const pc87309_t *dev = (pc87309_t *) priv;
+    uint8_t          ret = 0xff;
+    uint8_t          index;
 
     index = (port & 1) ? 0 : 1;
 
diff --git a/src/sio/sio_pc87311.c b/src/sio/sio_pc87311.c
index 143712692..9740753d1 100644
--- a/src/sio/sio_pc87311.c
+++ b/src/sio/sio_pc87311.c
@@ -122,7 +122,7 @@ pc87311_write(uint16_t addr, uint8_t val, void *priv)
 static uint8_t
 pc87311_read(UNUSED(uint16_t addr), void *priv)
 {
-    pc87311_t *dev = (pc87311_t *) priv;
+    const pc87311_t *dev = (pc87311_t *) priv;
 
     return dev->regs[dev->index];
 }
diff --git a/src/sio/sio_prime3b.c b/src/sio/sio_prime3b.c
index 32be854c7..c93630516 100644
--- a/src/sio/sio_prime3b.c
+++ b/src/sio/sio_prime3b.c
@@ -143,7 +143,7 @@ prime3b_write(uint16_t addr, uint8_t val, void *priv)
 static uint8_t
 prime3b_read(UNUSED(uint16_t addr), void *priv)
 {
-    prime3b_t *dev = (prime3b_t *) priv;
+    const prime3b_t *dev = (prime3b_t *) priv;
 
     return dev->regs[dev->index];
 }
diff --git a/src/sio/sio_prime3c.c b/src/sio/sio_prime3c.c
index 160f23aab..b19f861bf 100644
--- a/src/sio/sio_prime3c.c
+++ b/src/sio/sio_prime3c.c
@@ -207,7 +207,7 @@ prime3c_write(uint16_t addr, uint8_t val, void *priv)
 static uint8_t
 prime3c_read(UNUSED(uint16_t addr), void *priv)
 {
-    prime3c_t *dev = (prime3c_t *) priv;
+    const prime3c_t *dev = (prime3c_t *) priv;
 
     return dev->regs[dev->index];
 }
diff --git a/src/sio/sio_um8669f.c b/src/sio/sio_um8669f.c
index 7ddb143af..2643e76f7 100644
--- a/src/sio/sio_um8669f.c
+++ b/src/sio/sio_um8669f.c
@@ -187,6 +187,7 @@ um8669f_pnp_config_changed(uint8_t ld, isapnp_device_config_t *config, void *pri
                 um8669f_log("UM8669F: Game port disabled\n");
                 gameport_remap(dev->gameport, 0);
             }
+            break;
 
         default:
             break;
@@ -223,8 +224,8 @@ um8669f_write(uint16_t port, uint8_t val, void *priv)
 uint8_t
 um8669f_read(uint16_t port, void *priv)
 {
-    um8669f_t *dev = (um8669f_t *) priv;
-    uint8_t    ret = 0xff;
+    const um8669f_t *dev = (um8669f_t *) priv;
+    uint8_t          ret = 0xff;
 
     if (!dev->locked) {
         if (port == 0x108)