rp2/rp2_pio: Validate state machine frequency in constructor.
Fixes issue
@@ -462,13 +462,24 @@ STATIC mp_obj_t rp2_state_machine_init_helper(const rp2_state_machine_obj_t *sel
}
// Compute the clock divider.
- float div;
+ uint16_t clkdiv_int;
+ uint8_t clkdiv_frac;
if (args[ARG_freq].u_int < 0) {
- div = 1;
+ // Default: run at CPU frequency.
+ clkdiv_int = 1;
+ clkdiv_frac = 0;
} else if (args[ARG_freq].u_int == 0) {
- div = 0;
+ // Special case of 0: set clkdiv to 0.
+ clkdiv_int = 0;
+ clkdiv_frac = 0;
} else {
- div = (float)clock_get_hz(clk_sys) / (float)args[ARG_freq].u_int;
+ // Frequency given in Hz, compute clkdiv from it.
+ uint64_t div = (uint64_t)clock_get_hz(clk_sys) * 256ULL / (uint64_t)args[ARG_freq].u_int;
+ if (!(div >= 1 * 256 && div <= 65536 * 256)) {
+ mp_raise_ValueError(MP_ERROR_TEXT("freq out of range"));
+ }
+ clkdiv_int = div / 256;
+ clkdiv_frac = div & 0xff;
}
// Disable and reset the state machine.
@@ -476,7 +487,7 @@ STATIC mp_obj_t rp2_state_machine_init_helper(const rp2_state_machine_obj_t *sel
// Build the state machine config.
pio_sm_config config = pio_get_default_sm_config();
- sm_config_set_clkdiv(&config, div);
+ sm_config_set_clkdiv_int_frac(&config, clkdiv_int, clkdiv_frac);
config.execctrl = mp_obj_get_int_truncated(prog[PROG_EXECCTRL]);
config.shiftctrl = mp_obj_get_int_truncated(prog[PROG_SHIFTCTRL]);
