Once a PWM Capture has been initiated, the capture call enables a rising edge detection IRQ, then waits. Once each of the 3 phase changes have been recorded the thread then wakes. The remaining part of the call carries out the relevant calculations and passes back a formatted string to the caller. Signed-off-by: Lee Jones <lee.jones@xxxxxxxxxx> --- drivers/pwm/pwm-sti.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c index 4686ba0..fcc80eb 100644 --- a/drivers/pwm/pwm-sti.c +++ b/drivers/pwm/pwm-sti.c @@ -24,6 +24,8 @@ #include <linux/time.h> #include <linux/wait.h> +#define SECS_TO_NANOSECS(x) ((x) * 1000 * 1000 * 1000) + #define PWM_OUT_VAL(x) (0x00 + (4 * (x))) /* Device's Duty Cycle register */ #define PWM_CPT_VAL(x) (0x10 + (4 * (x))) /* Capture value */ #define PWM_CPT_EDGE(x) (0x30 + (4 * (x))) /* Edge to capture on */ @@ -305,7 +307,88 @@ static void sti_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm) clear_bit(pwm->hwpwm, &pc->configured); } +static int sti_pwm_capture(struct pwm_chip *chip, struct pwm_device *pwm, + struct pwm_capture *result, unsigned long timeout) +{ + struct sti_pwm_chip *pc = to_sti_pwmchip(chip); + struct sti_pwm_compat_data *cdata = pc->cdata; + struct sti_cpt_ddata *ddata = pwm_get_chip_data(pwm); + struct device *dev = pc->dev; + unsigned int effective_ticks; + unsigned long long high, low; + int ret; + + if (pwm->hwpwm > cdata->cpt_num_devs - 1) { + dev_err(dev, "Device %d is not valid\n", pwm->hwpwm); + return -EINVAL; + } + + mutex_lock(&ddata->lock); + + /* Prepare capture measurement */ + ddata->index = 0; + regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_RISING); + regmap_field_write(pc->pwm_cpt_int_en, BIT(pwm->hwpwm)); + + /* Enable capture */ + ret = regmap_field_write(pc->pwm_cpt_en, 1); + if (ret) { + dev_err(dev, "failed to enable PWM capture %d\n", pwm->hwpwm); + goto out; + } + + ret = wait_event_interruptible_timeout(ddata->wait, + ddata->index > 1, + msecs_to_jiffies(timeout)); + + regmap_write(pc->regmap, PWM_CPT_EDGE(pwm->hwpwm), CPT_EDGE_DISABLED); + + if (ret == -ERESTARTSYS) + goto out; + + switch (ddata->index) { + case 0: + case 1: + /* + * Getting here could mean : + * - input signal is constant of less than 1Hz + * - there is no input signal at all + * + * In such case the frequency is rounded down to 0 + */ + + result->period = 0; + result->duty_cycle = 0; + + break; + case 2: + /* We have everying we need */ + high = ddata->snapshot[1] - ddata->snapshot[0]; + low = ddata->snapshot[2] - ddata->snapshot[1]; + + effective_ticks = clk_get_rate(pc->cpt_clk); + + result->period = SECS_TO_NANOSECS(high + low); + result->period /= effective_ticks; + + result->duty_cycle = SECS_TO_NANOSECS(high); + result->duty_cycle /= effective_ticks; + + break; + default: + dev_err(dev, "Internal error\n"); + } + +out: + /* Disable capture */ + regmap_field_write(pc->pwm_cpt_en, 0); + + mutex_unlock(&ddata->lock); + return ret; +} + static const struct pwm_ops sti_pwm_ops = { + .capture = sti_pwm_capture, .config = sti_pwm_config, .enable = sti_pwm_enable, .disable = sti_pwm_disable, @@ -418,6 +501,11 @@ static int sti_pwm_probe_dt(struct sti_pwm_chip *pc) if (IS_ERR(pc->pwm_out_en)) return PTR_ERR(pc->pwm_out_en); + pc->pwm_cpt_en = devm_regmap_field_alloc(dev, pc->regmap, + reg_fields[PWM_CPT_EN]); + if (IS_ERR(pc->pwm_cpt_en)) + return PTR_ERR(pc->pwm_cpt_en); + pc->pwm_cpt_int_en = devm_regmap_field_alloc(dev, pc->regmap, reg_fields[PWM_CPT_INT_EN]); if (IS_ERR(pc->pwm_cpt_int_en)) -- 2.9.0 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html