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fefa713b18
The PWM device provided by Chrome OS EC doesn't really support anything other than setting a relative duty cycle. To support it as a backlight, this patch makes the PWM period optional in the device tree and pretends the valid brightness range is its period_ns. Also adds a sandbox test for a PWM channel that has a fixed period, checking that the resulting duty_cycle matches on a set_config() even if the requested period_ns can't be set. Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com> Reviewed-by: Simon Glass <sjg@chromium.org>
121 lines
2.6 KiB
C
121 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (c) 2015 Google, Inc
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* Written by Simon Glass <sjg@chromium.org>
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*/
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#include <common.h>
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#include <dm.h>
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#include <errno.h>
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#include <pwm.h>
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#include <asm/test.h>
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enum {
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NUM_CHANNELS = 3,
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};
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/**
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* struct sandbox_pwm_chan - a sandbox PWM channel
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*
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* @period_ns: Period of the PWM in nanoseconds
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* @duty_ns: Current duty cycle of the PWM in nanoseconds
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* @enable: true if the PWM is enabled
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* @polarity: true if the PWM polarity is active high
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*/
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struct sandbox_pwm_chan {
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uint period_ns;
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uint duty_ns;
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bool enable;
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bool polarity;
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};
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struct sandbox_pwm_priv {
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struct sandbox_pwm_chan chan[NUM_CHANNELS];
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};
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int sandbox_pwm_get_config(struct udevice *dev, uint channel, uint *period_nsp,
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uint *duty_nsp, bool *enablep, bool *polarityp)
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{
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struct sandbox_pwm_priv *priv = dev_get_priv(dev);
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struct sandbox_pwm_chan *chan;
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if (channel >= NUM_CHANNELS)
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return -ENOSPC;
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chan = &priv->chan[channel];
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*period_nsp = chan->period_ns;
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*duty_nsp = chan->duty_ns;
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*enablep = chan->enable;
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*polarityp = chan->polarity;
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return 0;
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}
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static int sandbox_pwm_set_config(struct udevice *dev, uint channel,
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uint period_ns, uint duty_ns)
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{
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struct sandbox_pwm_priv *priv = dev_get_priv(dev);
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struct sandbox_pwm_chan *chan;
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if (channel >= NUM_CHANNELS)
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return -ENOSPC;
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chan = &priv->chan[channel];
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if (channel == 2) {
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/* Pretend to have some fixed period */
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chan->period_ns = 4096;
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chan->duty_ns = duty_ns * 4096 / period_ns;
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} else {
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chan->period_ns = period_ns;
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chan->duty_ns = duty_ns;
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}
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return 0;
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}
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static int sandbox_pwm_set_enable(struct udevice *dev, uint channel,
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bool enable)
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{
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struct sandbox_pwm_priv *priv = dev_get_priv(dev);
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struct sandbox_pwm_chan *chan;
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if (channel >= NUM_CHANNELS)
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return -ENOSPC;
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chan = &priv->chan[channel];
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chan->enable = enable;
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return 0;
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}
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static int sandbox_pwm_set_invert(struct udevice *dev, uint channel,
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bool polarity)
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{
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struct sandbox_pwm_priv *priv = dev_get_priv(dev);
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struct sandbox_pwm_chan *chan;
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if (channel >= NUM_CHANNELS)
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return -ENOSPC;
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chan = &priv->chan[channel];
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chan->polarity = polarity;
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return 0;
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}
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static const struct pwm_ops sandbox_pwm_ops = {
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.set_config = sandbox_pwm_set_config,
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.set_enable = sandbox_pwm_set_enable,
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.set_invert = sandbox_pwm_set_invert,
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};
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static const struct udevice_id sandbox_pwm_ids[] = {
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{ .compatible = "sandbox,pwm" },
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{ }
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};
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U_BOOT_DRIVER(warm_pwm_sandbox) = {
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.name = "pwm_sandbox",
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.id = UCLASS_PWM,
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.of_match = sandbox_pwm_ids,
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.ops = &sandbox_pwm_ops,
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.priv_auto = sizeof(struct sandbox_pwm_priv),
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};
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