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rp2/rp2_pio: Validate state machine frequency in constructor.

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Fixes issue #7025.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George 2021-03-15 16:42:58 +11:00
parent 42035e5ede
commit 2c9af1c1d7
1 changed files with 16 additions and 5 deletions
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21
ports/rp2/rp2_pio.c
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@ -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]);