Gpio to gpout clock handle (#2561)

* add gpio_to_gpout_clock_handle to encapsulate GPIO->gpout mapping

* oops; wrong parenthesis placement

Author: kilograham

src/rp2_common/hardware_clocks/clocks.c

@@ -243,21 +243,8 @@ void clocks_enable_resus(resus_callback_t resus_callback) {
 }
 
 void clock_gpio_init_int_frac16(uint gpio, uint src, uint32_t div_int, uint16_t div_frac16) {
-    // Bit messy but it's as much code to loop through a lookup
-    // table. The sources for each gpout generators are the same
-    // so just call with the sources from GP0
-    uint gpclk = 0;
-    if      (gpio == 21) gpclk = clk_gpout0;
-    else if (gpio == 23) gpclk = clk_gpout1;
-    else if (gpio == 24) gpclk = clk_gpout2;
-    else if (gpio == 25) gpclk = clk_gpout3;
-#if !PICO_RP2040
-    else if (gpio == 13) gpclk = clk_gpout0;
-    else if (gpio == 15) gpclk = clk_gpout1;
-#endif
-    else {
-        invalid_params_if(HARDWARE_CLOCKS, true);
-    }
+    // note this includes an invalid_params_if before defaulting to clk_gpout0
+    uint gpclk = gpio_to_gpout_clock_handle(gpio, clk_gpout0);
 
     invalid_params_if(HARDWARE_CLOCKS, div_int >> REG_FIELD_WIDTH(CLOCKS_CLK_GPOUT0_DIV_INT));
     // Set up the gpclk generator

src/rp2_common/hardware_clocks/include/hardware/clocks.h

@@ -577,6 +577,42 @@ static inline bool set_sys_clock_khz(uint32_t freq_khz, bool required) {
     return false;
 }
 
+#define GPIO_TO_GPOUT_CLOCK_HANDLE_RP2040(gpio, default_clk_handle) \
+    ((gpio) == 21 ? clk_gpout0 :                        \
+        ((gpio) == 23 ? clk_gpout1 :                    \
+            ((gpio) == 24 ? clk_gpout2 :                \
+                ((gpio) == 25 ? clk_gpout3 :            \
+                    (default_clk_handle)))))
+
+#define GPIO_TO_GPOUT_CLOCK_HANDLE_RP2350(gpio, default_clk_handle) \
+    ((gpio) == 13 ? clk_gpout0 :                        \
+        ((gpio) == 15 ? clk_gpout1 :                    \
+            (GPIO_TO_GPOUT_CLOCK_HANDLE_RP2040(gpio, default_clk_handle))))
+
+/**
+ * \def GPIO_TO_GPOUT_CLOCK_HANDLE(gpio, default_clk_handle)
+ * \ingroup hardware_clocks
+ * \hideinitializer
+ * \brief Returns the GPOUT clock number associated with a particular GPIO if there is one, or default_clk_handle otherwise
+ *
+ * Note this macro is intended to resolve at compile time, and does no parameter checking
+ */
+#ifndef GPIO_TO_GPOUT_CLOCK_HANDLE
+#if PICO_RP2040
+#define GPIO_TO_GPOUT_CLOCK_HANDLE GPIO_TO_GPOUT_CLOCK_HANDLE_RP2040
+#else
+#define GPIO_TO_GPOUT_CLOCK_HANDLE GPIO_TO_GPOUT_CLOCK_HANDLE_RP2350
+#endif
+#endif
+    
+/**
+ * \brief return the associated GPOUT clock for a given GPIO if any
+ * \ingroup hardware_clocks
+ * \return the GPOUT clock number associated with a particular GPIO or default_clk_handle otherwise
+ */
+static inline clock_handle_t gpio_to_gpout_clock_handle(uint gpio, clock_handle_t default_clk_handle) {
+    return GPIO_TO_GPOUT_CLOCK_HANDLE(gpio, ({invalid_params_if(HARDWARE_CLOCKS, true); default_clk_handle;}));
+}
 #ifdef __cplusplus
 }
 #endif