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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>
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
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
View File

@ -3,14 +3,17 @@ VIA/Wondermedia VT8500/WM8xxx series SoC PWM controller
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>;

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);
}
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;