diff options
Diffstat (limited to 'drivers/pwm/pwm-omap-dmtimer.c')
| -rw-r--r-- | drivers/pwm/pwm-omap-dmtimer.c | 34 |
1 files changed, 30 insertions, 4 deletions
diff --git a/drivers/pwm/pwm-omap-dmtimer.c b/drivers/pwm/pwm-omap-dmtimer.c index 0083e75d950f..54641e45f45b 100644 --- a/drivers/pwm/pwm-omap-dmtimer.c +++ b/drivers/pwm/pwm-omap-dmtimer.c @@ -119,15 +119,13 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, fclk = omap->pdata->get_fclk(omap->dm_timer); if (!fclk) { dev_err(chip->dev, "invalid pmtimer fclk\n"); - mutex_unlock(&omap->mutex); - return -EINVAL; + goto err_einval; } clk_rate = clk_get_rate(fclk); if (!clk_rate) { dev_err(chip->dev, "invalid pmtimer fclk rate\n"); - mutex_unlock(&omap->mutex); - return -EINVAL; + goto err_einval; } dev_dbg(chip->dev, "clk rate: %luHz\n", clk_rate); @@ -142,6 +140,8 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, * The non-active time is the remainder: (DM_TIMER_MAX-match_value) * clock cycles. * + * NOTE: It is required that: load_value <= match_value < DM_TIMER_MAX + * * References: * OMAP4430/60/70 TRM sections 22.2.4.10 and 22.2.4.11 * AM335x Sitara TRM sections 20.1.3.5 and 20.1.3.6 @@ -149,6 +149,27 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, period_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, period_ns); duty_cycles = pwm_omap_dmtimer_get_clock_cycles(clk_rate, duty_ns); + if (period_cycles < 2) { + dev_info(chip->dev, + "period %d ns too short for clock rate %lu Hz\n", + period_ns, clk_rate); + goto err_einval; + } + + if (duty_cycles < 1) { + dev_dbg(chip->dev, + "duty cycle %d ns is too short for clock rate %lu Hz\n", + duty_ns, clk_rate); + dev_dbg(chip->dev, "using minimum of 1 clock cycle\n"); + duty_cycles = 1; + } else if (duty_cycles >= period_cycles) { + dev_dbg(chip->dev, + "duty cycle %d ns is too long for period %d ns at clock rate %lu Hz\n", + duty_ns, period_ns, clk_rate); + dev_dbg(chip->dev, "using maximum of 1 clock cycle less than period\n"); + duty_cycles = period_cycles - 1; + } + load_value = (DM_TIMER_MAX - period_cycles) + 1; match_value = load_value + duty_cycles - 1; @@ -179,6 +200,11 @@ static int pwm_omap_dmtimer_config(struct pwm_chip *chip, mutex_unlock(&omap->mutex); return 0; + +err_einval: + mutex_unlock(&omap->mutex); + + return -EINVAL; } static int pwm_omap_dmtimer_set_polarity(struct pwm_chip *chip, |