update previous fix as 1.0 < clkdiv < 2.0 IS supported on RP2350 (raspberrypi#2255)

* update previous fix as 1.0 < clkdiv < 2.0 IS supported on RP2350

Author: kilograham

src/rp2_common/hardware_clocks/clocks.c

@@ -101,12 +101,22 @@ bool clock_configure(clock_handle_t clock, uint32_t src, uint32_t auxsrc, uint32
     if (freq > src_freq)
         return false;
 
-    uint32_t div = (uint32_t)((((uint64_t) src_freq) << CLOCKS_CLK_GPOUT0_DIV_INT_LSB) / freq);
-    // only clock divider of 1, or  >= 2 are supported
-    if (div < (2u << CLOCKS_CLK_GPOUT0_DIV_INT_LSB)) {
-        div = (1u << CLOCKS_CLK_GPOUT0_DIV_INT_LSB);
+    uint64_t div64 =((((uint64_t) src_freq) << CLOCKS_CLK_GPOUT0_DIV_INT_LSB) / freq);
+    uint32_t div, actual_freq;
+    if (div64 >> 32) {
+        // set div to 0 for maximum clock divider
+        div = 0;
+        actual_freq = src_freq >> (32 - CLOCKS_CLK_GPOUT0_DIV_INT_LSB);
+    } else {
+        div = div64;
+#if PICO_RP2040
+        // on RP2040 only clock divider of 1, or  >= 2 are supported
+        if (div < (2u << CLOCKS_CLK_GPOUT0_DIV_INT_LSB)) {
+            div = (1u << CLOCKS_CLK_GPOUT0_DIV_INT_LSB);
+        }
+#endif
+        actual_freq = (uint32_t) ((((uint64_t) src_freq) << CLOCKS_CLK_GPOUT0_DIV_INT_LSB) / div);
     }
-    uint32_t actual_freq = (uint32_t) ((((uint64_t) src_freq) << CLOCKS_CLK_GPOUT0_DIV_INT_LSB) / div);
 
     clock_configure_internal(clock, src, auxsrc, actual_freq, div);
     // Store the configured frequency

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

@@ -269,16 +269,22 @@ typedef clock_num_t clock_handle_t;
  * frequency to be specified, and will set the clock divider to achieve the exact or higher frequency
  * achievable, with the maximum being the src_freq.
  *
- * Note: That the clock hardware only support divisors of exactly 1 or 2.0->65535.0
+ * \if rp2350_specific
+ * Note: The RP2350 clock hardware supports divisors from 1.0->65536.0 in steps of 1/65536
  *
- * See the tables in the description for details on the possible values for clock sources.
+ * \endif
+ * \if rp2040_specific
+ * Note: The RP2040 clock hardware only supports divisors of exactly 1.0 or 2.0->16777216.0 in steps of 1/256
+ * \endif
  *
+ * See the tables in the description for details on the possible values for clock sources.
  *
  * \param clock The clock to configure
  * \param src The main clock source, can be 0.
  * \param auxsrc The auxiliary clock source, which depends on which clock is being set. Can be 0
  * \param src_freq Frequency of the input clock source
  * \param freq Requested frequency
+ * \return true if the clock is updated, false if freq > src_freq
  */
 bool clock_configure(clock_handle_t clock, uint32_t src, uint32_t auxsrc, uint32_t src_freq, uint32_t freq);