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pwm: vt8500: Add polarity support

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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>
This commit is contained in:
Tony Prisk 2013-01-03 08:44:16 +13:00 committed by Thierry Reding
parent 8ab432caa4
commit 3ccb1c1702
2 changed files with 29 additions and 3 deletions
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9
Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
View file

@ -3,14 +3,17 @@ VIA/Wondermedia VT8500/WM8xxx series SoC PWM controller
Required properties: Required properties:
- compatible: should be "via,vt8500-pwm" - compatible: should be "via,vt8500-pwm"
- reg: physical base address and length of the controller's registers - reg: physical base address and length of the controller's registers
- #pwm-cells: should be 2. The first cell specifies the per-chip index - #pwm-cells: Should be 3. Number of cells being used to specify PWM property.
of the PWM to use and the second cell is the period in nanoseconds. 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 - clocks: phandle to the PWM source clock
Example: Example:
pwm1: pwm@d8220000 { pwm1: pwm@d8220000 {
#pwm-cells = <2>; #pwm-cells = <3>;
compatible = "via,vt8500-pwm"; compatible = "via,vt8500-pwm";
reg = <0xd8220000 0x1000>; reg = <0xd8220000 0x1000>;
clocks = <&clkpwm>; clocks = <&clkpwm>;

23
drivers/pwm/pwm-vt8500.c
View file

@ -164,10 +164,31 @@ static void vt8500_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
clk_disable(vt8500->clk); 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 = { static struct pwm_ops vt8500_pwm_ops = {
.enable = vt8500_pwm_enable, .enable = vt8500_pwm_enable,
.disable = vt8500_pwm_disable, .disable = vt8500_pwm_disable,
.config = vt8500_pwm_config, .config = vt8500_pwm_config,
.set_polarity = vt8500_pwm_set_polarity,
.owner = THIS_MODULE, .owner = THIS_MODULE,
}; };
@ -197,6 +218,8 @@ static int vt8500_pwm_probe(struct platform_device *pdev)
chip->chip.dev = &pdev->dev; chip->chip.dev = &pdev->dev;
chip->chip.ops = &vt8500_pwm_ops; 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.base = -1;
chip->chip.npwm = VT8500_NR_PWMS; chip->chip.npwm = VT8500_NR_PWMS;