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>
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@ -3,14 +3,17 @@ VIA/Wondermedia VT8500/WM8xxx series SoC PWM controller
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Required properties:
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- compatible: should be "via,vt8500-pwm"
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- reg: physical base address and length of the controller's registers
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- #pwm-cells: should be 2. The first cell specifies the per-chip index
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of the PWM to use and the second cell is the period in nanoseconds.
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- #pwm-cells: Should be 3. Number of cells being used to specify PWM property.
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First cell specifies the per-chip index of the PWM to use, the second
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cell is the period in nanoseconds and bit 0 in the third cell is used to
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encode the polarity of PWM output. Set bit 0 of the third in PWM specifier
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to 1 for inverse polarity & set to 0 for normal polarity.
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- clocks: phandle to the PWM source clock
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Example:
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pwm1: pwm@d8220000 {
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#pwm-cells = <2>;
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#pwm-cells = <3>;
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compatible = "via,vt8500-pwm";
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reg = <0xd8220000 0x1000>;
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clocks = <&clkpwm>;
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@ -164,10 +164,31 @@ static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
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clk_disable(vt8500->clk);
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}
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static int vt8500_pwm_set_polarity(struct pwm_chip *chip,
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struct pwm_device *pwm,
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enum pwm_polarity polarity)
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{
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struct vt8500_chip *vt8500 = to_vt8500_chip(chip);
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u32 val;
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val = readl(vt8500->base + REG_CTRL(pwm->hwpwm));
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if (polarity == PWM_POLARITY_INVERSED)
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val |= CTRL_INVERT;
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else
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val &= ~CTRL_INVERT;
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writel(val, vt8500->base + REG_CTRL(pwm->hwpwm));
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pwm_busy_wait(vt8500, pwm->hwpwm, STATUS_CTRL_UPDATE);
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return 0;
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}
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static struct pwm_ops vt8500_pwm_ops = {
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.enable = vt8500_pwm_enable,
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.disable = vt8500_pwm_disable,
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.config = vt8500_pwm_config,
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.set_polarity = vt8500_pwm_set_polarity,
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.owner = THIS_MODULE,
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};
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@ -197,6 +218,8 @@ static int vt8500_pwm_probe(struct platform_device *pdev)
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chip->chip.dev = &pdev->dev;
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chip->chip.ops = &vt8500_pwm_ops;
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chip->chip.of_xlate = of_pwm_xlate_with_flags;
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chip->chip.of_pwm_n_cells = 3;
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chip->chip.base = -1;
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chip->chip.npwm = VT8500_NR_PWMS;
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