pwm: vt8500: Add polarity support

Required properties:

- compatible: should be "via,vt8500-pwm"

- reg: physical base address and length of the controller's registers

- #pwm-cells: should be 2.  The first cell specifies the per-chip index

  of the PWM to use and the second cell is the period in nanoseconds.

- #pwm-cells: Should be 3. Number of cells being used to specify PWM property.

  First cell specifies the per-chip index of the PWM to use, the second

  cell is the period in nanoseconds and bit 0 in the third cell is used to

  encode the polarity of PWM output. Set bit 0 of the third in PWM specifier

  to 1 for inverse polarity & set to 0 for normal polarity.

- clocks: phandle to the PWM source clock

Example:

pwm1: pwm@d8220000 {

	#pwm-cells = <2>;

	#pwm-cells = <3>;

	compatible = "via,vt8500-pwm";

	reg = <0xd8220000 0x1000>;

	clocks = <&clkpwm>;

	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,

};

	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;