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 <li...@prisktech.co.nz>
---
v2:
Change binding document to detail flags usage.
Add missing .of_xlate function
Add missing .of_pwm_n_cells
.../devicetree/bindings/pwm/vt8500-pwm.txt | 9 +++++---
drivers/pwm/pwm-vt8500.c | 23 ++++++++++++++++++++
2 files changed, 29 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
b/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
index bcc6367..d21d82d 100644
--- a/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
+++ b/Documentation/devicetree/bindings/pwm/vt8500-pwm.txt
@@ -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>;
diff --git a/drivers/pwm/pwm-vt8500.c b/drivers/pwm/pwm-vt8500.c
index bbc3750..98d79e9 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;
--
1.7.9.5
--
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