pwm: mxs: Add support for inverse polarity

If I'm reading of_pwm_xlate_with_flags() right, existing device trees
that set #pwm-cells = 2 will continue to work.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>

diff --git a/drivers/pwm/pwm-mxs.c b/drivers/pwm/pwm-mxs.c
index 5a6835e..5756222 100644 (file)
--- a/drivers/pwm/pwm-mxs.c
+++ b/drivers/pwm/pwm-mxs.c
@@ -25,8 +25,11 @@
 #define  PERIOD_PERIOD(p)      ((p) & 0xffff)
 #define  PERIOD_PERIOD_MAX     0x10000
 #define  PERIOD_ACTIVE_HIGH    (3 << 16)
+#define  PERIOD_ACTIVE_LOW     (2 << 16)
+#define  PERIOD_INACTIVE_HIGH  (3 << 18)
 #define  PERIOD_INACTIVE_LOW   (2 << 18)
 #define  PERIOD_POLARITY_NORMAL        (PERIOD_ACTIVE_HIGH | PERIOD_INACTIVE_LOW)
+#define  PERIOD_POLARITY_INVERSE       (PERIOD_ACTIVE_LOW | PERIOD_INACTIVE_HIGH)
 #define  PERIOD_CDIV(div)      (((div) & 0x7) << 20)
 #define  PERIOD_CDIV_MAX       8
 
@@ -50,9 +53,7 @@ static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
        unsigned int period_cycles, duty_cycles;
        unsigned long rate;
        unsigned long long c;
-
-       if (state->polarity != PWM_POLARITY_NORMAL)
-               return -ENOTSUPP;
+       unsigned int pol_bits;
 
        /*
         * If the PWM channel is disabled, make sure to turn on the
@@ -91,9 +92,12 @@ static int mxs_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
         * only take effect at the beginning of a new period, avoiding
         * glitches.
         */
+
+       pol_bits = state->polarity == PWM_POLARITY_NORMAL ?
+               PERIOD_POLARITY_NORMAL : PERIOD_POLARITY_INVERSE;
        writel(duty_cycles << 16,
               mxs->base + PWM_ACTIVE0 + pwm->hwpwm * 0x20);
-       writel(PERIOD_PERIOD(period_cycles) | PERIOD_POLARITY_NORMAL | PERIOD_CDIV(div),
+       writel(PERIOD_PERIOD(period_cycles) | pol_bits | PERIOD_CDIV(div),
               mxs->base + PWM_PERIOD0 + pwm->hwpwm * 0x20);
 
        if (state->enabled) {
@@ -135,6 +139,8 @@ static int mxs_pwm_probe(struct platform_device *pdev)
 
        mxs->chip.dev = &pdev->dev;
        mxs->chip.ops = &mxs_pwm_ops;
+       mxs->chip.of_xlate = of_pwm_xlate_with_flags;
+       mxs->chip.of_pwm_n_cells = 3;
        mxs->chip.base = -1;
 
        ret = of_property_read_u32(np, "fsl,pwm-number", &mxs->chip.npwm);