atsam: Add support for SAM E70

Signed-off-by: Alex Maclean <monkeh@monkeh.net>

src/atsam/Kconfig

@@ -9,7 +9,7 @@ config ATSAM_SELECT
     select HAVE_GPIO_ADC
     select HAVE_GPIO_I2C
     select HAVE_GPIO_SPI
-    select HAVE_GPIO_HARD_PWM
+    select HAVE_GPIO_HARD_PWM if !MACH_SAME70
     select HAVE_GPIO_BITBANGING
     select HAVE_STRICT_TIMING
     select HAVE_CHIPID
@@ -33,6 +33,9 @@ choice
     config MACH_SAM4E8E
         bool "SAM4e8e (Duet Wifi/Eth)"
         select MACH_SAM4E
+    config MACH_SAME70Q20B
+        bool "SAME70Q20B (Duet 3 6HC)"
+        select MACH_SAME70
 endchoice
 
 config MACH_SAM3X
@@ -45,6 +48,8 @@ config MACH_SAM4S
 config MACH_SAM4E
     bool
     select MACH_SAM4
+config MACH_SAME70
+    bool
 
 config MCU
     string
@@ -52,15 +57,17 @@ config MCU
     default "sam3x8c" if MACH_SAM3X8C
     default "sam4s8c" if MACH_SAM4S8C
     default "sam4e8e" if MACH_SAM4E8E
+    default "same70q20b" if MACH_SAME70Q20B
 
 config CLOCK_FREQ
     int
     default 84000000 if MACH_SAM3X
     default 120000000 if MACH_SAM4
+    default 300000000 if MACH_SAME70
 
 config FLASH_START
     hex
-    default 0x400000 if MACH_SAM4
+    default 0x400000 if MACH_SAM4 || MACH_SAME70
     default 0x80000
 
 config FLASH_SIZE
@@ -69,12 +76,14 @@ config FLASH_SIZE
 
 config RAM_START
     hex
+    default 0x20400000 if MACH_SAME70
     default 0x20000000
 
 config RAM_SIZE
     hex
     default 0x18000 if MACH_SAM3X
     default 0x20000 if MACH_SAM4
+    default 0x40000 if MACH_SAME70
 
 config STACK_SIZE
     int