diff --git a/boards/b-l072z-lrwan1/include/periph_conf.h b/boards/b-l072z-lrwan1/include/periph_conf.h
index 80d28470c4..dd988e14c4 100644
--- a/boards/b-l072z-lrwan1/include/periph_conf.h
+++ b/boards/b-l072z-lrwan1/include/periph_conf.h
@@ -109,7 +109,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
@@ -128,7 +128,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/b-l475e-iot01a/include/periph_conf.h b/boards/b-l475e-iot01a/include/periph_conf.h
index 6b129e041c..65c79b52d1 100644
--- a/boards/b-l475e-iot01a/include/periph_conf.h
+++ b/boards/b-l475e-iot01a/include/periph_conf.h
@@ -146,7 +146,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/firefly/include/periph_conf.h b/boards/firefly/include/periph_conf.h
index 56e984d7c2..23a35adaef 100644
--- a/boards/firefly/include/periph_conf.h
+++ b/boards/firefly/include/periph_conf.h
@@ -39,7 +39,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 1),
         .miso_pin = GPIO_PIN(PORT_B, 3),
         .sck_pin  = GPIO_PIN(PORT_B, 2),
-        .cs_pin   = GPIO_UNDEF
+        .cs_pin   = SPI_CS_UNDEF,
     },
     {
         .num      = 1,
diff --git a/boards/frdm-k22f/include/periph_conf.h b/boards/frdm-k22f/include/periph_conf.h
index 7e9ea7aa6e..a4f5908887 100644
--- a/boards/frdm-k22f/include/periph_conf.h
+++ b/boards/frdm-k22f/include/periph_conf.h
@@ -241,9 +241,9 @@ static const spi_conf_t spi_config[] = {
         .pin_cs   = {
             GPIO_PIN(PORT_C, 4),
             GPIO_PIN(PORT_D, 4),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI0_MASK
diff --git a/boards/frdm-k64f/include/periph_conf.h b/boards/frdm-k64f/include/periph_conf.h
index 3afa5c7e30..bc94d95423 100644
--- a/boards/frdm-k64f/include/periph_conf.h
+++ b/boards/frdm-k64f/include/periph_conf.h
@@ -237,10 +237,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_D, 1),
         .pin_cs   = {
             GPIO_PIN(PORT_D, 0),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI0_MASK
diff --git a/boards/frdm-kw41z/include/periph_conf.h b/boards/frdm-kw41z/include/periph_conf.h
index ed054ea0b6..2d1f26c32f 100644
--- a/boards/frdm-kw41z/include/periph_conf.h
+++ b/boards/frdm-kw41z/include/periph_conf.h
@@ -40,10 +40,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_C, 16),
         .pin_cs   = {
             GPIO_PIN(PORT_C, 19),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI0_MASK
@@ -55,10 +55,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_A, 18),
         .pin_cs   = {
             GPIO_PIN(PORT_A, 19),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI1_MASK
diff --git a/boards/im880b/include/periph_conf.h b/boards/im880b/include/periph_conf.h
index 778a5b273b..1bd1b771b0 100644
--- a/boards/im880b/include/periph_conf.h
+++ b/boards/im880b/include/periph_conf.h
@@ -84,7 +84,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/iotlab-a8-m3/include/periph_conf.h b/boards/iotlab-a8-m3/include/periph_conf.h
index 0b31b05493..8b7c6f469a 100644
--- a/boards/iotlab-a8-m3/include/periph_conf.h
+++ b/boards/iotlab-a8-m3/include/periph_conf.h
@@ -37,7 +37,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .rccmask  = RCC_APB1ENR_SPI2EN,
         .apbbus   = APB1
     }
diff --git a/boards/iotlab-m3/include/periph_conf.h b/boards/iotlab-m3/include/periph_conf.h
index 791a09859d..6e6ed6b9b4 100644
--- a/boards/iotlab-m3/include/periph_conf.h
+++ b/boards/iotlab-m3/include/periph_conf.h
@@ -37,7 +37,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .rccmask  = RCC_APB2ENR_SPI1EN,
         .apbbus   = APB2,
 #ifdef MODULE_PERIPH_DMA
@@ -53,7 +53,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .rccmask  = RCC_APB1ENR_SPI2EN,
         .apbbus   = APB1,
 #ifdef MODULE_PERIPH_DMA
diff --git a/boards/limifrog-v1/include/periph_conf.h b/boards/limifrog-v1/include/periph_conf.h
index a3fdd27e8f..b492bf7bae 100644
--- a/boards/limifrog-v1/include/periph_conf.h
+++ b/boards/limifrog-v1/include/periph_conf.h
@@ -88,7 +88,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
@@ -101,7 +101,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF6,
         .miso_af  = GPIO_AF6,
         .sclk_af  = GPIO_AF6,
diff --git a/boards/lora-e5-dev/include/periph_conf.h b/boards/lora-e5-dev/include/periph_conf.h
index 35fd68360b..8c7e6c94c8 100644
--- a/boards/lora-e5-dev/include/periph_conf.h
+++ b/boards/lora-e5-dev/include/periph_conf.h
@@ -100,7 +100,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_UNDEF,
         .miso_pin = GPIO_UNDEF,
         .sclk_pin = GPIO_UNDEF,
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF_UNDEF,
         .miso_af  = GPIO_AF_UNDEF,
         .sclk_af  = GPIO_AF_UNDEF,
@@ -115,7 +115,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 10),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/lsn50/include/periph_conf.h b/boards/lsn50/include/periph_conf.h
index e6e6df7a17..7995000a7b 100644
--- a/boards/lsn50/include/periph_conf.h
+++ b/boards/lsn50/include/periph_conf.h
@@ -108,7 +108,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/maple-mini/include/periph_conf.h b/boards/maple-mini/include/periph_conf.h
index d642b103c6..2a4782829f 100644
--- a/boards/maple-mini/include/periph_conf.h
+++ b/boards/maple-mini/include/periph_conf.h
@@ -134,7 +134,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A,  7),
         .miso_pin = GPIO_PIN(PORT_A,  6),
         .sclk_pin = GPIO_PIN(PORT_A,  5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .rccmask  = RCC_APB2ENR_SPI1EN,
         .apbbus   = APB2
     },
@@ -143,7 +143,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .rccmask  = RCC_APB1ENR_SPI2EN,
         .apbbus   = APB1
     }
diff --git a/boards/mulle/include/periph_conf.h b/boards/mulle/include/periph_conf.h
index 303ddfd2c3..220ea1de7e 100644
--- a/boards/mulle/include/periph_conf.h
+++ b/boards/mulle/include/periph_conf.h
@@ -312,7 +312,7 @@ static const spi_conf_t spi_config[] = {
             GPIO_PIN(PORT_D, 4),
             GPIO_PIN(PORT_D, 5),
             GPIO_PIN(PORT_D, 6),
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI0_MASK
@@ -324,10 +324,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_E, 2),
         .pin_cs   = {
             GPIO_PIN(PORT_E, 4),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI1_MASK
diff --git a/boards/nucleo-f031k6/include/periph_conf.h b/boards/nucleo-f031k6/include/periph_conf.h
index 1bc732e4d4..725157ffca 100644
--- a/boards/nucleo-f031k6/include/periph_conf.h
+++ b/boards/nucleo-f031k6/include/periph_conf.h
@@ -100,7 +100,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/nucleo-f042k6/include/periph_conf.h b/boards/nucleo-f042k6/include/periph_conf.h
index 5d2c69a0ec..d63db22037 100644
--- a/boards/nucleo-f042k6/include/periph_conf.h
+++ b/boards/nucleo-f042k6/include/periph_conf.h
@@ -110,7 +110,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/nucleo-f103rb/include/periph_conf.h b/boards/nucleo-f103rb/include/periph_conf.h
index c5db89ef2c..665fd38d93 100644
--- a/boards/nucleo-f103rb/include/periph_conf.h
+++ b/boards/nucleo-f103rb/include/periph_conf.h
@@ -154,7 +154,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .rccmask  = RCC_APB2ENR_SPI1EN,
         .apbbus   = APB2
     },
@@ -163,7 +163,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .rccmask  = RCC_APB1ENR_SPI2EN,
         .apbbus   = APB1
     }
diff --git a/boards/nucleo-f303k8/include/periph_conf.h b/boards/nucleo-f303k8/include/periph_conf.h
index 7022048783..dc8eca27cd 100644
--- a/boards/nucleo-f303k8/include/periph_conf.h
+++ b/boards/nucleo-f303k8/include/periph_conf.h
@@ -148,7 +148,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-f303re/include/periph_conf.h b/boards/nucleo-f303re/include/periph_conf.h
index 2519800bc9..3a8c5e956d 100644
--- a/boards/nucleo-f303re/include/periph_conf.h
+++ b/boards/nucleo-f303re/include/periph_conf.h
@@ -161,7 +161,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_C, 12),
         .miso_pin = GPIO_PIN(PORT_C, 11),
         .sclk_pin = GPIO_PIN(PORT_C, 10),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF6,
         .miso_af  = GPIO_AF6,
         .sclk_af  = GPIO_AF6,
diff --git a/boards/nucleo-f303ze/include/periph_conf.h b/boards/nucleo-f303ze/include/periph_conf.h
index 0b36610fe5..1109a35248 100644
--- a/boards/nucleo-f303ze/include/periph_conf.h
+++ b/boards/nucleo-f303ze/include/periph_conf.h
@@ -158,7 +158,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-f446ze/include/periph_conf.h b/boards/nucleo-f446ze/include/periph_conf.h
index c970b4cf51..d9db59adc1 100644
--- a/boards/nucleo-f446ze/include/periph_conf.h
+++ b/boards/nucleo-f446ze/include/periph_conf.h
@@ -150,7 +150,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-f746zg/include/periph_conf.h b/boards/nucleo-f746zg/include/periph_conf.h
index fa37b626f9..134c10a42d 100644
--- a/boards/nucleo-f746zg/include/periph_conf.h
+++ b/boards/nucleo-f746zg/include/periph_conf.h
@@ -175,7 +175,7 @@ static const spi_conf_t spi_config[] = {
 #endif
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
@@ -194,7 +194,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_E, 6),
         .miso_pin = GPIO_PIN(PORT_E, 5),
         .sclk_pin = GPIO_PIN(PORT_E, 2),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-f767zi/include/periph_conf.h b/boards/nucleo-f767zi/include/periph_conf.h
index c7625abae4..fad6af755c 100644
--- a/boards/nucleo-f767zi/include/periph_conf.h
+++ b/boards/nucleo-f767zi/include/periph_conf.h
@@ -135,7 +135,7 @@ static const spi_conf_t spi_config[] = {
 #endif
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
@@ -148,7 +148,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_E, 6),
         .miso_pin = GPIO_PIN(PORT_E, 5),
         .sclk_pin = GPIO_PIN(PORT_E, 2),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-l011k4/include/periph_conf.h b/boards/nucleo-l011k4/include/periph_conf.h
index 27282c674e..daee04d74f 100644
--- a/boards/nucleo-l011k4/include/periph_conf.h
+++ b/boards/nucleo-l011k4/include/periph_conf.h
@@ -68,7 +68,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/nucleo-l031k6/include/periph_conf.h b/boards/nucleo-l031k6/include/periph_conf.h
index e5b4f563bc..cbab34377b 100644
--- a/boards/nucleo-l031k6/include/periph_conf.h
+++ b/boards/nucleo-l031k6/include/periph_conf.h
@@ -90,7 +90,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/nucleo-l053r8/include/periph_conf.h b/boards/nucleo-l053r8/include/periph_conf.h
index a9fced3ce3..a9cbce20f7 100644
--- a/boards/nucleo-l053r8/include/periph_conf.h
+++ b/boards/nucleo-l053r8/include/periph_conf.h
@@ -102,7 +102,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/nucleo-l073rz/include/periph_conf.h b/boards/nucleo-l073rz/include/periph_conf.h
index 54adcabf02..da052fa06e 100644
--- a/boards/nucleo-l073rz/include/periph_conf.h
+++ b/boards/nucleo-l073rz/include/periph_conf.h
@@ -120,7 +120,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/nucleo-l152re/include/periph_conf.h b/boards/nucleo-l152re/include/periph_conf.h
index 10d3b8fc37..a76be9c581 100644
--- a/boards/nucleo-l152re/include/periph_conf.h
+++ b/boards/nucleo-l152re/include/periph_conf.h
@@ -143,7 +143,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-l412kb/include/periph_conf.h b/boards/nucleo-l412kb/include/periph_conf.h
index 9657369c72..1323e43a42 100644
--- a/boards/nucleo-l412kb/include/periph_conf.h
+++ b/boards/nucleo-l412kb/include/periph_conf.h
@@ -105,7 +105,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-l432kc/include/periph_conf.h b/boards/nucleo-l432kc/include/periph_conf.h
index 9b8c31022d..40fd526183 100644
--- a/boards/nucleo-l432kc/include/periph_conf.h
+++ b/boards/nucleo-l432kc/include/periph_conf.h
@@ -103,7 +103,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-l433rc/include/periph_conf.h b/boards/nucleo-l433rc/include/periph_conf.h
index 6f818daf75..9afa75259d 100644
--- a/boards/nucleo-l433rc/include/periph_conf.h
+++ b/boards/nucleo-l433rc/include/periph_conf.h
@@ -104,7 +104,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-l452re/include/periph_conf.h b/boards/nucleo-l452re/include/periph_conf.h
index b290c0c483..d653623143 100644
--- a/boards/nucleo-l452re/include/periph_conf.h
+++ b/boards/nucleo-l452re/include/periph_conf.h
@@ -107,7 +107,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-l476rg/include/periph_conf.h b/boards/nucleo-l476rg/include/periph_conf.h
index bfc304eaa2..72ffa469ca 100644
--- a/boards/nucleo-l476rg/include/periph_conf.h
+++ b/boards/nucleo-l476rg/include/periph_conf.h
@@ -187,7 +187,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-l496zg/include/periph_conf.h b/boards/nucleo-l496zg/include/periph_conf.h
index 819775158e..600725936a 100644
--- a/boards/nucleo-l496zg/include/periph_conf.h
+++ b/boards/nucleo-l496zg/include/periph_conf.h
@@ -143,7 +143,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-l4r5zi/include/periph_conf.h b/boards/nucleo-l4r5zi/include/periph_conf.h
index 2758e68376..2f0fb4c89f 100644
--- a/boards/nucleo-l4r5zi/include/periph_conf.h
+++ b/boards/nucleo-l4r5zi/include/periph_conf.h
@@ -104,7 +104,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nucleo-wl55jc/include/periph_conf.h b/boards/nucleo-wl55jc/include/periph_conf.h
index 2d6551ca52..89156bd782 100644
--- a/boards/nucleo-wl55jc/include/periph_conf.h
+++ b/boards/nucleo-wl55jc/include/periph_conf.h
@@ -89,7 +89,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_UNDEF,
         .miso_pin = GPIO_UNDEF,
         .sclk_pin = GPIO_UNDEF,
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF_UNDEF,
         .miso_af  = GPIO_AF_UNDEF,
         .sclk_af  = GPIO_AF_UNDEF,
@@ -104,7 +104,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/nz32-sc151/include/periph_conf.h b/boards/nz32-sc151/include/periph_conf.h
index 86a5abf280..d8a2b1a69d 100644
--- a/boards/nz32-sc151/include/periph_conf.h
+++ b/boards/nz32-sc151/include/periph_conf.h
@@ -101,7 +101,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
@@ -114,7 +114,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
@@ -127,7 +127,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_C, 12),
         .miso_pin = GPIO_PIN(PORT_C, 11),
         .sclk_pin = GPIO_PIN(PORT_C, 10),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF6,
         .miso_af  = GPIO_AF6,
         .sclk_af  = GPIO_AF6,
diff --git a/boards/openlabs-kw41z-mini/include/periph_conf.h b/boards/openlabs-kw41z-mini/include/periph_conf.h
index 3278c172bf..80df305cff 100644
--- a/boards/openlabs-kw41z-mini/include/periph_conf.h
+++ b/boards/openlabs-kw41z-mini/include/periph_conf.h
@@ -315,10 +315,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_C, 16),
         .pin_cs   = {
             GPIO_PIN(PORT_C, 19),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
         },
         .pcr      = (gpio_pcr_t)(GPIO_AF_2 | GPIO_IN_PU),
         .simmask  = SIM_SCGC6_SPI0_MASK
diff --git a/boards/p-l496g-cell02/include/periph_conf.h b/boards/p-l496g-cell02/include/periph_conf.h
index 6036d97ec5..d02b48b945 100644
--- a/boards/p-l496g-cell02/include/periph_conf.h
+++ b/boards/p-l496g-cell02/include/periph_conf.h
@@ -135,7 +135,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/p-nucleo-wb55/include/periph_conf.h b/boards/p-nucleo-wb55/include/periph_conf.h
index 18129271c4..aa71095987 100644
--- a/boards/p-nucleo-wb55/include/periph_conf.h
+++ b/boards/p-nucleo-wb55/include/periph_conf.h
@@ -91,7 +91,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/pba-d-01-kw2x/include/periph_conf.h b/boards/pba-d-01-kw2x/include/periph_conf.h
index 1466491b40..0bf510be48 100644
--- a/boards/pba-d-01-kw2x/include/periph_conf.h
+++ b/boards/pba-d-01-kw2x/include/periph_conf.h
@@ -223,10 +223,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_C, 5),
         .pin_cs   = {
             GPIO_PIN(PORT_C, 4),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI0_MASK
@@ -238,10 +238,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_B, 11),
         .pin_cs   = {
             GPIO_PIN(PORT_B, 10),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI1_MASK
diff --git a/boards/phynode-kw41z/include/periph_conf.h b/boards/phynode-kw41z/include/periph_conf.h
index 9b4cbb037d..808f0623a6 100644
--- a/boards/phynode-kw41z/include/periph_conf.h
+++ b/boards/phynode-kw41z/include/periph_conf.h
@@ -42,10 +42,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_A, 18),
         .pin_cs   = {
             GPIO_PIN(PORT_A, 19),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI1_MASK
diff --git a/boards/remote-pa/include/periph_conf.h b/boards/remote-pa/include/periph_conf.h
index 8fd0e54014..f352349840 100644
--- a/boards/remote-pa/include/periph_conf.h
+++ b/boards/remote-pa/include/periph_conf.h
@@ -65,7 +65,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(2, 7),
         .miso_pin = GPIO_PIN(0, 4),
         .sck_pin  = GPIO_PIN(1 ,5),
-        .cs_pin   = GPIO_UNDEF
+        .cs_pin   = SPI_CS_UNDEF,
     }
 };
 
diff --git a/boards/spark-core/include/periph_conf.h b/boards/spark-core/include/periph_conf.h
index c697802656..5e14320191 100644
--- a/boards/spark-core/include/periph_conf.h
+++ b/boards/spark-core/include/periph_conf.h
@@ -83,7 +83,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 17),
         .miso_pin = GPIO_PIN(PORT_B, 16),
         .sclk_pin = GPIO_PIN(PORT_B, 15),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .rccmask  = RCC_APB2ENR_SPI1EN,
         .apbbus   = APB2
     }
diff --git a/boards/stm32f0discovery/include/periph_conf.h b/boards/stm32f0discovery/include/periph_conf.h
index 5560dc6bcf..80ed7af6fb 100644
--- a/boards/stm32f0discovery/include/periph_conf.h
+++ b/boards/stm32f0discovery/include/periph_conf.h
@@ -112,7 +112,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
@@ -125,7 +125,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_B, 13),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/stm32f3discovery/include/periph_conf.h b/boards/stm32f3discovery/include/periph_conf.h
index 8c480da712..ea7f7d9ccf 100644
--- a/boards/stm32f3discovery/include/periph_conf.h
+++ b/boards/stm32f3discovery/include/periph_conf.h
@@ -145,7 +145,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_A, 7),
         .miso_pin = GPIO_PIN(PORT_A, 6),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/stm32f723e-disco/include/periph_conf.h b/boards/stm32f723e-disco/include/periph_conf.h
index 035112f29c..3e7f4dabbe 100644
--- a/boards/stm32f723e-disco/include/periph_conf.h
+++ b/boards/stm32f723e-disco/include/periph_conf.h
@@ -173,7 +173,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_A, 5),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/stm32f746g-disco/include/periph_conf.h b/boards/stm32f746g-disco/include/periph_conf.h
index 026f06dbfd..6664a527fd 100644
--- a/boards/stm32f746g-disco/include/periph_conf.h
+++ b/boards/stm32f746g-disco/include/periph_conf.h
@@ -128,7 +128,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 15),
         .miso_pin = GPIO_PIN(PORT_B, 14),
         .sclk_pin = GPIO_PIN(PORT_I, 1),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF5,
         .miso_af  = GPIO_AF5,
         .sclk_af  = GPIO_AF5,
diff --git a/boards/stm32l0538-disco/include/periph_conf.h b/boards/stm32l0538-disco/include/periph_conf.h
index d71c85b863..f1eb325511 100644
--- a/boards/stm32l0538-disco/include/periph_conf.h
+++ b/boards/stm32l0538-disco/include/periph_conf.h
@@ -79,7 +79,7 @@ static const spi_conf_t spi_config[] = {
         .mosi_pin = GPIO_PIN(PORT_B, 5),
         .miso_pin = GPIO_PIN(PORT_B, 4),
         .sclk_pin = GPIO_PIN(PORT_B, 3),
-        .cs_pin   = GPIO_UNDEF,
+        .cs_pin   = SPI_CS_UNDEF,
         .mosi_af  = GPIO_AF0,
         .miso_af  = GPIO_AF0,
         .sclk_af  = GPIO_AF0,
diff --git a/boards/usb-kw41z/include/periph_conf.h b/boards/usb-kw41z/include/periph_conf.h
index c607b38394..46b09271e6 100644
--- a/boards/usb-kw41z/include/periph_conf.h
+++ b/boards/usb-kw41z/include/periph_conf.h
@@ -39,10 +39,10 @@ static const spi_conf_t spi_config[] = {
         .pin_clk  = GPIO_PIN(PORT_A, 18),
         .pin_cs   = {
             GPIO_PIN(PORT_A, 19),
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF,
-            GPIO_UNDEF
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
+            SPI_CS_UNDEF,
         },
         .pcr      = GPIO_AF_2,
         .simmask  = SIM_SCGC6_SPI1_MASK
diff --git a/cpu/cc2538/include/periph_cpu.h b/cpu/cc2538/include/periph_cpu.h
index dc33a056b0..b0254c6f2f 100644
--- a/cpu/cc2538/include/periph_cpu.h
+++ b/cpu/cc2538/include/periph_cpu.h
@@ -220,6 +220,21 @@ typedef enum {
 #define UART_TXBUF_SIZE    (64)
 #endif
 
+/**
+ * @brief   Define value for unused CS line
+ */
+#define SPI_CS_UNDEF        (GPIO_UNDEF)
+
+#ifndef DOXYGEN
+/**
+ * @brief   Overwrite the default spi_cs_t type definition
+ * @{
+ */
+#define HAVE_SPI_CS_T
+typedef uint32_t spi_cs_t;
+/** @} */
+#endif
+
 /**
  * @name   Override SPI mode settings
  * @{
@@ -282,7 +297,7 @@ typedef struct {
     gpio_t mosi_pin;        /**< pin used for MOSI */
     gpio_t miso_pin;        /**< pin used for MISO */
     gpio_t sck_pin;         /**< pin used for SCK */
-    gpio_t cs_pin;          /**< pin used for CS */
+    spi_cs_t cs_pin;        /**< pin used for CS */
 } spi_conf_t;
 /** @} */
 
diff --git a/cpu/kinetis/include/periph_cpu.h b/cpu/kinetis/include/periph_cpu.h
index 6cec6d6c23..5c17ab1824 100644
--- a/cpu/kinetis/include/periph_cpu.h
+++ b/cpu/kinetis/include/periph_cpu.h
@@ -115,6 +115,21 @@ typedef uint16_t gpio_t;
  */
 #define SPI_HWCS_NUMOF      (5)
 
+/**
+ * @brief   Define value for unused CS line
+ */
+#define SPI_CS_UNDEF        (GPIO_UNDEF)
+
+#ifndef DOXYGEN
+/**
+ * @brief   Overwrite the default spi_cs_t type definition
+ * @{
+ */
+#define HAVE_SPI_CS_T
+typedef uint32_t spi_cs_t;
+/** @} */
+#endif
+
 /**
  * @name    This CPU makes use of the following shared SPI functions
  * @{
@@ -454,7 +469,7 @@ typedef struct {
     gpio_t pin_miso;                    /**< MISO pin used */
     gpio_t pin_mosi;                    /**< MOSI pin used */
     gpio_t pin_clk;                     /**< CLK pin used */
-    gpio_t pin_cs[SPI_HWCS_NUMOF];      /**< pins used for HW cs lines */
+    spi_cs_t pin_cs[SPI_HWCS_NUMOF];    /**< pins used for HW cs lines */
 #ifdef KINETIS_HAVE_PCR
     gpio_pcr_t pcr;                     /**< alternate pin function values */
 #endif /* KINETIS_HAVE_PCR */
diff --git a/cpu/kinetis/periph/spi.c b/cpu/kinetis/periph/spi.c
index 52da320b2f..193277f01d 100644
--- a/cpu/kinetis/periph/spi.c
+++ b/cpu/kinetis/periph/spi.c
@@ -30,6 +30,7 @@
 
 #include "cpu.h"
 #include "mutex.h"
+#include "periph/gpio.h"
 #include "periph/spi.h"
 
 #define ENABLE_DEBUG        0
@@ -135,8 +136,7 @@ int spi_init_cs(spi_t bus, spi_cs_t cs)
         gpio_init((gpio_t)cs, GPIO_OUT);
     }
     else {
-        if ((cs >= SPI_HWCS_NUMOF) ||
-            (spi_config[bus].pin_cs[cs] == GPIO_UNDEF)) {
+        if ((cs >= SPI_HWCS_NUMOF) || !gpio_is_valid(spi_config[bus].pin_cs[cs])) {
             return SPI_NOCS;
         }
         gpio_init_port(spi_config[bus].pin_cs[cs], spi_config[bus].pcr);
diff --git a/cpu/stm32/include/periph/cpu_spi.h b/cpu/stm32/include/periph/cpu_spi.h
index b3155a202e..2ead5233e0 100644
--- a/cpu/stm32/include/periph/cpu_spi.h
+++ b/cpu/stm32/include/periph/cpu_spi.h
@@ -48,6 +48,21 @@ extern "C" {
  */
 #define SPI_HWCS(x)         (SPI_HWCS_MASK | x)
 
+/**
+ * @brief   Define value for unused CS line
+ */
+#define SPI_CS_UNDEF        (GPIO_UNDEF)
+
+#ifndef DOXYGEN
+/**
+ * @brief   Overwrite the default spi_cs_t type definition
+ * @{
+ */
+#define HAVE_SPI_CS_T
+typedef uint32_t spi_cs_t;
+/** @} */
+#endif
+
 /**
  * @brief   Use the shared SPI functions
  * @{
@@ -87,7 +102,7 @@ typedef struct {
     gpio_t mosi_pin;        /**< MOSI pin */
     gpio_t miso_pin;        /**< MISO pin */
     gpio_t sclk_pin;        /**< SCLK pin */
-    gpio_t cs_pin;          /**< HWCS pin, set to GPIO_UNDEF if not mapped */
+    spi_cs_t cs_pin;        /**< HWCS pin, set to SPI_CS_UNDEF if not mapped */
 #ifndef CPU_FAM_STM32F1
     gpio_af_t mosi_af;      /**< MOSI pin alternate function */
     gpio_af_t miso_af;      /**< MISO pin alternate function */
diff --git a/cpu/stm32/periph/spi.c b/cpu/stm32/periph/spi.c
index 856257e97c..cd8fcc82a8 100644
--- a/cpu/stm32/periph/spi.c
+++ b/cpu/stm32/periph/spi.c
@@ -31,6 +31,7 @@
 #include "bitarithm.h"
 #include "cpu.h"
 #include "mutex.h"
+#include "periph/gpio.h"
 #include "periph/spi.h"
 #include "pm_layered.h"
 
@@ -166,13 +167,13 @@ int spi_init_cs(spi_t bus, spi_cs_t cs)
     if (bus >= SPI_NUMOF) {
         return SPI_NODEV;
     }
-    if (cs == SPI_CS_UNDEF ||
+    if (!gpio_is_valid(cs) ||
         (((cs & SPI_HWCS_MASK) == SPI_HWCS_MASK) && (cs & ~(SPI_HWCS_MASK)))) {
         return SPI_NOCS;
     }
 
     if (cs == SPI_HWCS_MASK) {
-        if (spi_config[bus].cs_pin == GPIO_UNDEF) {
+        if (!gpio_is_valid(spi_config[bus].cs_pin)) {
             return SPI_NOCS;
         }
 #ifdef CPU_FAM_STM32F1
@@ -393,7 +394,7 @@ void spi_transfer_bytes(spi_t bus, spi_cs_t cs, bool cont,
 
     /* active the given chip select line */
     dev(bus)->CR1 |= (SPI_CR1_SPE);     /* this pulls the HW CS line low */
-    if ((cs != SPI_HWCS_MASK) && (cs != SPI_CS_UNDEF)) {
+    if ((cs != SPI_HWCS_MASK) && gpio_is_valid(cs)) {
         gpio_clear((gpio_t)cs);
     }
 
@@ -409,7 +410,7 @@ void spi_transfer_bytes(spi_t bus, spi_cs_t cs, bool cont,
 #endif
 
     /* release the chip select if not specified differently */
-    if ((!cont) && (cs != SPI_CS_UNDEF)) {
+    if ((!cont) && gpio_is_valid(cs)) {
         dev(bus)->CR1 &= ~(SPI_CR1_SPE);    /* pull HW CS line high */
         if (cs != SPI_HWCS_MASK) {
             gpio_set((gpio_t)cs);