[RESEND 09/11] pwm: sti: Add PWM Capture call-back

Lee Jones
2016-03-02T15:34:30Z

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@linaro.org>
---
drivers/pwm/pwm-sti.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 72 insertions(+)

diff --git a/drivers/pwm/pwm-sti.c b/drivers/pwm/pwm-sti.c
index 82a69e4..8de9b4a 100644
--- a/drivers/pwm/pwm-sti.c
+++ b/drivers/pwm/pwm-sti.c
@@ -309,7 +309,79 @@ 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,
+ int channel, char *buf)
+{
+ struct sti_pwm_chip *pc = to_sti_pwmchip(chip);
+ struct sti_pwm_compat_data *cdata = pc->cdata;
+ struct sti_cpt_data *d = pc->cpt_data[channel];
+ struct device *dev = pc->dev;
+ unsigned int f, dc;
+ unsigned int high, low;
+ bool level;
+ int ret;
+
+ if (channel > cdata->cpt_num_chan - 1) {
+ dev_err(dev, "Channel %d is not valid\n", channel);
+ return -EINVAL;
+ }
+
+ mutex_lock(&d->lock);
+
+ /* Prepare capture measurement */
+ d->index = 0;
+ regmap_write(pc->regmap, PWM_CPT_EDGE(channel), CPT_EDGE_RISING);
+ regmap_field_write(pc->pwm_cpt_int_en, BIT(channel));
+ ret = wait_event_interruptible_timeout(d->wait, d->index > 1, HZ);
+
+ /*
+ * In case we woke up for another reason than completion
+ * make sure to disable the capture.
+ */
+ regmap_write(pc->regmap, PWM_CPT_EDGE(channel), CPT_EDGE_DISABLED);
+
+ if (ret == -ERESTARTSYS)
+ goto out;
+
+ switch (d->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
+ * level of the supposed constant signal is reported
+ * using duty cycle min and max values.
+ */
+ level = gpio_get_value(d->gpio);
+
+ ret = sprintf(buf, "0:%u\n", level ? CPT_DC_MAX : 0);
+ break;
+ case 2:
+ /* We have evertying we need */
+ high = d->snapshot[1] - d->snapshot[0];
+ low = d->snapshot[2] - d->snapshot[1];
+
+ /* Calculate frequency in Hz */
+ f = clk_get_rate(pc->cpt_clk) / (1 * (high + low));
+
+ /* Calculate the duty cycle */
+ dc = CPT_DC_MAX * high / (high + low);
+
+ ret = sprintf(buf, "%u:%u\n", f, dc);
+ default:
+ dev_err(dev, "Internal error\n");
+ }
+
+out:
+ mutex_unlock(&d->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,
--
1.9.1