add PICO_USE_FASTEST_SUPPORTED_CLOCK, and support vreg setting and SYS_CLOCK_MHZ=200 for rp2040

[kilograham]

Also adds vreg_get_voltage()

[P33M]

IMO SYS_CLK_VREG_VOLTAGE_MIN is misnamed - it's a frequency scaling operating point, not a minimum. If you're not wanting to boost clk_sys then the "minimum" shouldn't be applied, as it just wastes power. Such OPPs are usually referred to as turbo/boost settings.

[lurch]

There are a couple of small tweaks needed to stop tools/extract_configs.py getting upset...

diff --git a/src/rp2040/hardware_regs/include/hardware/platform_defs.h b/src/rp2040/hardware_regs/include/hardware/platform_defs.h
index e1d368e..9566e1f 100644
--- a/src/rp2040/hardware_regs/include/hardware/platform_defs.h
+++ b/src/rp2040/hardware_regs/include/hardware/platform_defs.h
@@ -69,6 +69,9 @@
 #define SYS_CLK_HZ ((SYS_CLK_MHZ) * _u(1000000))
 #else
 // PICO_CONFIG: PICO_USE_FASTEST_SUPPORTED_CLOCK, Use the fastest officially supported clock by default, type=bool, default=0, group=hardware_base
+#ifndef PICO_USE_FASTEST_SUPPORTED_CLOCK
+#define PICO_USE_FASTEST_SUPPORTED_CLOCK 0
+#endif
 #if PICO_USE_FASTEST_SUPPORTED_CLOCK
 #define SYS_CLK_HZ _u(200000000)
 #else
diff --git a/src/rp2_common/hardware_clocks/include/hardware/clocks.h b/src/rp2_common/hardware_clocks/include/hardware/clocks.h
index 217bb7d..1a598cf 100644
--- a/src/rp2_common/hardware_clocks/include/hardware/clocks.h
+++ b/src/rp2_common/hardware_clocks/include/hardware/clocks.h
@@ -225,6 +225,10 @@ extern "C" {
 #ifndef PLL_SYS_POSTDIV2
 #define PLL_SYS_POSTDIV2                    1
 #endif
+#else
+#ifndef SYS_CLK_VREG_VOLTAGE_AUTO_ADJUST
+#define SYS_CLK_VREG_VOLTAGE_AUTO_ADJUST 0
+#endif
 #endif // PICO_RP2040 && SYS_CLK_KHZ == 200000 && XOSC_KHZ == 12000 && PLL_COMMON_REFDIV == 1
 
 #if !defined(PLL_SYS_VCO_FREQ_HZ) || !defined(PLL_SYS_POSTDIV1) || !defined(PLL_SYS_POSTDIV2)

[kilograham]

IMO SYS_CLK_VREG_VOLTAGE_MIN is misnamed - it's a frequency scaling operating point, not a minimum. If you're not wanting to boost clk_sys then the "minimum" shouldn't be applied, as it just wastes power. Such OPPs are usually referred to as turbo/boost settings.

It is the minimum voltage for the requested sys_clock; i.e. its value is dependent on the sys clock you choose, and the clock setup will increase the current voltage if it is less than this