pwm: vt8500: Add polarity support

Add support to set polarity on PWM devices, allowing for inverted
duty cycles.

Also update the binding document to #pwm-cells = <3> to allow
passing the flags from devicetree.

Signed-off-by: Tony Prisk <linux@prisktech.co.nz>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>

1 files changed, 23 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
index bbc37504103a..98d79e9f0144 100644
--- a/drivers/pwm/pwm-vt8500.c
+++ b/drivers/pwm/pwm-vt8500.c
@@ -164,10 +164,31 @@ static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
         clk_disable(vt8500->clk);
 }
 
+static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
+                                   struct pwm_device *pwm,
+                                   enum pwm_polarity polarity)
+{
+        struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
+        u32 val;
+
+        val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
+
+        if (polarity == PWM_POLARITY_INVERSED)
+                val |= CTRL_INVERT;
+        else
+                val &= ~CTRL_INVERT;
+
+        writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
+        pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
+
+        return 0;
+}
+
 static struct pwm_ops vt8500_pwm_ops = {
         .enable = vt8500_pwm_enable,
         .disable = vt8500_pwm_disable,
         .config = vt8500_pwm_config,
+        .set_polarity = vt8500_pwm_set_polarity,
         .owner = THIS_MODULE,
 };
 
@@ -197,6 +218,8 @@ static int vt8500_pwm_probe(struct platform_device *pdev)
 
         chip->chip.dev = &pdev->dev;
         chip->chip.ops = &vt8500_pwm_ops;
+        chip->chip.of_xlate = of_pwm_xlate_with_flags;
+        chip->chip.of_pwm_n_cells = 3;
         chip->chip.base = -1;
         chip->chip.npwm = VT8500_NR_PWMS;