Many backlights need to use a PWM to control the brightness. Add a driver for this. It understands the standard device tree binding.
Signed-off-by: Simon Glass sjg@chromium.org ---
drivers/video/Makefile | 3 + drivers/video/pwm_backlight.c | 134 ++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 137 insertions(+) create mode 100644 drivers/video/pwm_backlight.c
diff --git a/drivers/video/Makefile b/drivers/video/Makefile index fa90721..6d89532 100644 --- a/drivers/video/Makefile +++ b/drivers/video/Makefile @@ -10,6 +10,9 @@ obj-$(CONFIG_DISPLAY_PORT) += dp-uclass.o obj-$(CONFIG_DM_VIDEO) += backlight-uclass.o obj-$(CONFIG_DM_VIDEO) += video-uclass.o vidconsole-uclass.o console_normal.o obj-$(CONFIG_DM_VIDEO) += video_bmp.o +ifdef CONFIG_DM_VIDEO +obj-$(CONFIG_DM_PWM) += pwm_backlight.o +endif obj-$(CONFIG_VIDEO_ROTATION) += console_rotate.o endif
diff --git a/drivers/video/pwm_backlight.c b/drivers/video/pwm_backlight.c new file mode 100644 index 0000000..de6277f --- /dev/null +++ b/drivers/video/pwm_backlight.c @@ -0,0 +1,134 @@ +/* + * Copyright (c) 2016 Google, Inc + * Written by Simon Glass sjg@chromium.org + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <common.h> +#include <dm.h> +#include <backlight.h> +#include <pwm.h> +#include <asm/gpio.h> +#include <power/regulator.h> + +DECLARE_GLOBAL_DATA_PTR; + +struct pwm_backlight_priv { + struct udevice *reg; + struct gpio_desc enable; + struct udevice *pwm; + uint channel; + uint period_ns; + uint default_level; + uint min_level; + uint max_level; +}; + +static int pwm_backlight_enable(struct udevice *dev) +{ + struct pwm_backlight_priv *priv = dev_get_priv(dev); + uint duty_cycle; + int ret; + + debug("%s: Enable '%s', regulator '%s'\n", __func__, dev->name, + priv->reg->name); + ret = regulator_set_enable(priv->reg, true); + if (ret) { + debug("%s: Cannot enable regulator for PWM '%s'\n", __func__, + dev->name); + return ret; + } + mdelay(120); + + duty_cycle = priv->period_ns * (priv->default_level - priv->min_level) / + (priv->max_level - priv->min_level + 1); + ret = pwm_set_config(priv->pwm, priv->channel, priv->period_ns, + duty_cycle); + if (ret) + return ret; + ret = pwm_set_enable(priv->pwm, priv->channel, true); + if (ret) + return ret; + mdelay(10); + dm_gpio_set_value(&priv->enable, 1); + + return 0; +} + +static int pwm_backlight_ofdata_to_platdata(struct udevice *dev) +{ + struct pwm_backlight_priv *priv = dev_get_priv(dev); + struct fdtdec_phandle_args args; + const void *blob = gd->fdt_blob; + int node = dev->of_offset; + int index, ret, count, len; + const u32 *cell; + + ret = uclass_get_device_by_phandle(UCLASS_REGULATOR, dev, + "power-supply", &priv->reg); + if (ret) { + debug("%s: Cannot get power supply: ret=%d\n", __func__, ret); + return ret; + } + ret = gpio_request_by_name(dev, "enable-gpios", 0, &priv->enable, + GPIOD_IS_OUT); + if (ret) { + debug("%s: Warning: cannot get enable GPIO: ret=%d\n", + __func__, ret); + if (ret != -ENOENT) + return ret; + } + ret = fdtdec_parse_phandle_with_args(blob, node, "pwms", "#pwm-cells", + 0, 0, &args); + if (ret) { + debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret); + return ret; + } + + ret = uclass_get_device_by_of_offset(UCLASS_PWM, args.node, &priv->pwm); + if (ret) { + debug("%s: Cannot get PWM: ret=%d\n", __func__, ret); + return ret; + } + priv->channel = args.args[0]; + priv->period_ns = args.args[1]; + + index = fdtdec_get_int(blob, node, "default-brightness-level", 255); + cell = fdt_getprop(blob, node, "brightness-levels", &len); + count = len / sizeof(u32); + if (cell && count > index) { + priv->default_level = fdt32_to_cpu(cell[index]); + priv->max_level = fdt32_to_cpu(cell[count - 1]); + } else { + priv->default_level = index; + priv->max_level = 255; + } + + + return 0; +} + +static int pwm_backlight_probe(struct udevice *dev) +{ + return 0; +} + +static const struct backlight_ops pwm_backlight_ops = { + .enable = pwm_backlight_enable, +}; + +static const struct udevice_id pwm_backlight_ids[] = { + { .compatible = "pwm-backlight" }, + { } +}; + +U_BOOT_DRIVER(pwm_backlight) = { + .name = "pwm_backlight", + .id = UCLASS_PANEL_BACKLIGHT, + .of_match = pwm_backlight_ids, + .ops = &pwm_backlight_ops, + .ofdata_to_platdata = pwm_backlight_ofdata_to_platdata, + .probe = pwm_backlight_probe, + .priv_auto_alloc_size = sizeof(struct pwm_backlight_priv), +};