const struct pwm_state *state)
{
struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
- struct clk *clk = pwm_get_chip_data(pwm),
- *parent_clk = clk_get_parent(clk);
- unsigned long rate, period, duty;
- unsigned long long tmp;
- unsigned int prescaler = 0;
+ unsigned long long tmp = 0xffffull * NSEC_PER_SEC;
+ struct clk *clk = pwm_get_chip_data(pwm);
+ unsigned long period, duty;
uint16_t ctrl;
+ long rate;
int err;
- rate = clk_get_rate(parent_clk);
- tmp = (unsigned long long)rate * state->period;
- do_div(tmp, 1000000000);
- period = tmp;
+ /*
+ * Limit the clock to a maximum rate that still gives us a period value
+ * which fits in 16 bits.
+ */
+ do_div(tmp, state->period);
- while (period > 0xffff && prescaler < 6) {
- period >>= 2;
- rate >>= 2;
- ++prescaler;
+ /*
+ * /!\ IMPORTANT NOTE:
+ * -------------------
+ * This code relies on the fact that clk_round_rate() will always round
+ * down, which is not a valid assumption given by the clk API, but only
+ * happens to be true with the clk drivers used for Ingenic SoCs.
+ *
+ * Right now, there is no alternative as the clk API does not have a
+ * round-down function (and won't have one for a while), but if it ever
+ * comes to light, a round-down function should be used instead.
+ */
+ rate = clk_round_rate(clk, tmp);
+ if (rate < 0) {
+ dev_err(chip->dev, "Unable to round rate: %ld", rate);
+ return rate;
}
- if (prescaler == 6)
- return -EINVAL;
+ /* Calculate period value */
+ tmp = (unsigned long long)rate * state->period;
+ do_div(tmp, NSEC_PER_SEC);
+ period = (unsigned long)tmp;
+ /* Calculate duty value */
tmp = (unsigned long long)period * state->duty_cycle;
do_div(tmp, state->period);
duty = period - tmp;