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- Add support for MediaTek MT6370 Backlight
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Merge tag 'backlight-next-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight

Pull backlight update from Lee Jones:

 - Add support for MediaTek MT6370 Backlight

* tag 'backlight-next-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight:
  video: backlight: mt6370: Add MediaTek MT6370 support
  dt-bindings: backlight: Add MediaTek MT6370 backlight
This commit is contained in:
Linus Torvalds 2022-10-05 10:45:15 -07:00
commit a47e60729d
4 changed files with 486 additions and 0 deletions
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121
Documentation/devicetree/bindings/leds/backlight/mediatek,mt6370-backlight.yaml Normal file
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@ -0,0 +1,121 @@
# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
%YAML 1.2
---
$id: http://devicetree.org/schemas/leds/backlight/mediatek,mt6370-backlight.yaml#
$schema: http://devicetree.org/meta-schemas/core.yaml#
title: MediaTek MT6370 Backlight
maintainers:
- ChiaEn Wu <chiaen_wu@richtek.com>
description: |
This module is part of the MT6370 MFD device.
The MT6370 Backlight WLED driver supports up to a 29V output voltage for
4 channels of 8 series WLEDs. Each channel supports up to 30mA of current
capability with 2048 current steps (11 bits, only for MT6370/MT6371) or
16384 current steps (14 bits, only for MT6372) in exponential or linear
mapping curves.
allOf:
- $ref: common.yaml#
properties:
compatible:
enum:
- mediatek,mt6370-backlight
- mediatek,mt6372-backlight
default-brightness:
minimum: 0
max-brightness:
minimum: 0
enable-gpios:
description: External backlight 'enable' pin
maxItems: 1
mediatek,bled-pwm-enable:
description: |
Enable external PWM input for backlight dimming
type: boolean
mediatek,bled-pwm-hys-enable:
description: |
Enable the backlight input-hysteresis for PWM mode
type: boolean
mediatek,bled-pwm-hys-input-th-steps:
$ref: /schemas/types.yaml#/definitions/uint8
enum: [1, 4, 16, 64]
description: |
The selection of the upper and lower bounds threshold of backlight
PWM resolution. If we choose selection 64, the variation of PWM
resolution needs more than 64 steps.
mediatek,bled-ovp-shutdown:
description: |
Enable the backlight shutdown when OVP level triggered
type: boolean
mediatek,bled-ovp-microvolt:
enum: [17000000, 21000000, 25000000, 29000000]
description: |
Backlight OVP level selection.
mediatek,bled-ocp-shutdown:
description: |
Enable the backlight shutdown when OCP level triggerred.
type: boolean
mediatek,bled-ocp-microamp:
enum: [900000, 1200000, 1500000, 1800000]
description: |
Backlight OC level selection.
mediatek,bled-exponential-mode-enable:
description: |
Enable the exponential mode of backlight brightness. If this property
is not enabled, the default is to use linear mode.
type: boolean
mediatek,bled-channel-use:
$ref: /schemas/types.yaml#/definitions/uint8
description: |
Backlight LED channel to be used.
Each bit mapping to:
- 0: CH4
- 1: CH3
- 2: CH2
- 3: CH1
minimum: 1
maximum: 15
if:
properties:
compatible:
contains:
const: mediatek,mt6372-backlight
then:
properties:
default-brightness:
maximum: 16384
max-brightness:
maximum: 16384
else:
properties:
default-brightness:
maximum: 2048
max-brightness:
maximum: 2048
required:
- compatible
- mediatek,bled-channel-use
additionalProperties: false

13
drivers/video/backlight/Kconfig
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@ -268,6 +268,19 @@ config BACKLIGHT_MAX8925
If you have a LCD backlight connected to the WLED output of MAX8925
WLED output, say Y here to enable this driver.
config BACKLIGHT_MT6370
tristate "MediaTek MT6370 Backlight Driver"
depends on MFD_MT6370
help
This enables support for Mediatek MT6370 Backlight driver.
It's commonly used to drive the display WLED. There are 4 channels
inside, and each channel supports up to 30mA of current capability
with 2048 current steps (only for MT6370/MT6371) or 16384 current
steps (only for MT6372) in exponential or linear mapping curves.
This driver can also be built as a module. If so, the module
will be called "mt6370-backlight".
config BACKLIGHT_APPLE
tristate "Apple Backlight Driver"
depends on X86 && ACPI

1
drivers/video/backlight/Makefile
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@ -44,6 +44,7 @@ obj-$(CONFIG_BACKLIGHT_LP855X) += lp855x_bl.o
obj-$(CONFIG_BACKLIGHT_LP8788) += lp8788_bl.o
obj-$(CONFIG_BACKLIGHT_LV5207LP) += lv5207lp.o
obj-$(CONFIG_BACKLIGHT_MAX8925) += max8925_bl.o
obj-$(CONFIG_BACKLIGHT_MT6370) += mt6370-backlight.o
obj-$(CONFIG_BACKLIGHT_OMAP1) += omap1_bl.o
obj-$(CONFIG_BACKLIGHT_PANDORA) += pandora_bl.o
obj-$(CONFIG_BACKLIGHT_PCF50633) += pcf50633-backlight.o

351
drivers/video/backlight/mt6370-backlight.c Normal file
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@ -0,0 +1,351 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2022 Richtek Technology Corp.
*
* Author: ChiaEn Wu <chiaen_wu@richtek.com>
*/
#include <linux/backlight.h>
#include <linux/bitfield.h>
#include <linux/bits.h>
#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/minmax.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/regmap.h>
#define MT6370_REG_DEV_INFO 0x100
#define MT6370_REG_BL_EN 0x1A0
#define MT6370_REG_BL_BSTCTRL 0x1A1
#define MT6370_REG_BL_PWM 0x1A2
#define MT6370_REG_BL_DIM2 0x1A4
#define MT6370_VENID_MASK GENMASK(7, 4)
#define MT6370_BL_EXT_EN_MASK BIT(7)
#define MT6370_BL_EN_MASK BIT(6)
#define MT6370_BL_CODE_MASK BIT(0)
#define MT6370_BL_CH_MASK GENMASK(5, 2)
#define MT6370_BL_CH_SHIFT 2
#define MT6370_BL_DIM2_COMMON_MASK GENMASK(2, 0)
#define MT6370_BL_DIM2_COMMON_SHIFT 3
#define MT6370_BL_DIM2_6372_MASK GENMASK(5, 0)
#define MT6370_BL_DIM2_6372_SHIFT 6
#define MT6370_BL_PWM_EN_MASK BIT(7)
#define MT6370_BL_PWM_HYS_EN_MASK BIT(2)
#define MT6370_BL_PWM_HYS_SEL_MASK GENMASK(1, 0)
#define MT6370_BL_OVP_EN_MASK BIT(7)
#define MT6370_BL_OVP_SEL_MASK GENMASK(6, 5)
#define MT6370_BL_OVP_SEL_SHIFT 5
#define MT6370_BL_OC_EN_MASK BIT(3)
#define MT6370_BL_OC_SEL_MASK GENMASK(2, 1)
#define MT6370_BL_OC_SEL_SHIFT 1
#define MT6370_BL_PWM_HYS_TH_MIN_STEP 1
#define MT6370_BL_PWM_HYS_TH_MAX_STEP 64
#define MT6370_BL_OVP_MIN_UV 17000000
#define MT6370_BL_OVP_MAX_UV 29000000
#define MT6370_BL_OVP_STEP_UV 4000000
#define MT6370_BL_OCP_MIN_UA 900000
#define MT6370_BL_OCP_MAX_UA 1800000
#define MT6370_BL_OCP_STEP_UA 300000
#define MT6370_BL_MAX_COMMON_BRIGHTNESS 2048
#define MT6370_BL_MAX_6372_BRIGHTNESS 16384
#define MT6370_BL_MAX_CH 15
enum {
MT6370_VID_COMMON = 1,
MT6370_VID_6372,
};
struct mt6370_priv {
u8 dim2_mask;
u8 dim2_shift;
int def_max_brightness;
struct backlight_device *bl;
struct device *dev;
struct gpio_desc *enable_gpio;
struct regmap *regmap;
};
static int mt6370_bl_update_status(struct backlight_device *bl_dev)
{
struct mt6370_priv *priv = bl_get_data(bl_dev);
int brightness = backlight_get_brightness(bl_dev);
unsigned int enable_val;
u8 brightness_val[2];
int ret;
if (brightness) {
brightness_val[0] = (brightness - 1) & priv->dim2_mask;
brightness_val[1] = (brightness - 1) >> priv->dim2_shift;
ret = regmap_raw_write(priv->regmap, MT6370_REG_BL_DIM2,
brightness_val, sizeof(brightness_val));
if (ret)
return ret;
}
gpiod_set_value(priv->enable_gpio, !!brightness);
enable_val = brightness ? MT6370_BL_EN_MASK : 0;
return regmap_update_bits(priv->regmap, MT6370_REG_BL_EN,
MT6370_BL_EN_MASK, enable_val);
}
static int mt6370_bl_get_brightness(struct backlight_device *bl_dev)
{
struct mt6370_priv *priv = bl_get_data(bl_dev);
unsigned int enable;
u8 brightness_val[2];
int brightness, ret;
ret = regmap_read(priv->regmap, MT6370_REG_BL_EN, &enable);
if (ret)
return ret;
if (!(enable & MT6370_BL_EN_MASK))
return 0;
ret = regmap_raw_read(priv->regmap, MT6370_REG_BL_DIM2,
brightness_val, sizeof(brightness_val));
if (ret)
return ret;
brightness = brightness_val[1] << priv->dim2_shift;
brightness += brightness_val[0] & priv->dim2_mask;
return brightness + 1;
}
static const struct backlight_ops mt6370_bl_ops = {
.options = BL_CORE_SUSPENDRESUME,
.update_status = mt6370_bl_update_status,
.get_brightness = mt6370_bl_get_brightness,
};
static int mt6370_init_backlight_properties(struct mt6370_priv *priv,
struct backlight_properties *props)
{
struct device *dev = priv->dev;
u8 prop_val;
u32 brightness, ovp_uV, ocp_uA;
unsigned int mask, val;
int ret;
/* Vendor optional properties */
val = 0;
if (device_property_read_bool(dev, "mediatek,bled-pwm-enable"))
val |= MT6370_BL_PWM_EN_MASK;
if (device_property_read_bool(dev, "mediatek,bled-pwm-hys-enable"))
val |= MT6370_BL_PWM_HYS_EN_MASK;
ret = device_property_read_u8(dev,
"mediatek,bled-pwm-hys-input-th-steps",
&prop_val);
if (!ret) {
prop_val = clamp_val(prop_val,
MT6370_BL_PWM_HYS_TH_MIN_STEP,
MT6370_BL_PWM_HYS_TH_MAX_STEP);
prop_val = prop_val <= 1 ? 0 :
prop_val <= 4 ? 1 :
prop_val <= 16 ? 2 : 3;
val |= prop_val;
}
ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_PWM,
val, val);
if (ret)
return ret;
val = 0;
if (device_property_read_bool(dev, "mediatek,bled-ovp-shutdown"))
val |= MT6370_BL_OVP_EN_MASK;
ret = device_property_read_u32(dev, "mediatek,bled-ovp-microvolt",
&ovp_uV);
if (!ret) {
ovp_uV = clamp_val(ovp_uV, MT6370_BL_OVP_MIN_UV,
MT6370_BL_OVP_MAX_UV);
ovp_uV = DIV_ROUND_UP(ovp_uV - MT6370_BL_OVP_MIN_UV,
MT6370_BL_OVP_STEP_UV);
val |= ovp_uV << MT6370_BL_OVP_SEL_SHIFT;
}
if (device_property_read_bool(dev, "mediatek,bled-ocp-shutdown"))
val |= MT6370_BL_OC_EN_MASK;
ret = device_property_read_u32(dev, "mediatek,bled-ocp-microamp",
&ocp_uA);
if (!ret) {
ocp_uA = clamp_val(ocp_uA, MT6370_BL_OCP_MIN_UA,
MT6370_BL_OCP_MAX_UA);
ocp_uA = DIV_ROUND_UP(ocp_uA - MT6370_BL_OCP_MIN_UA,
MT6370_BL_OCP_STEP_UA);
val |= ocp_uA << MT6370_BL_OC_SEL_SHIFT;
}
ret = regmap_update_bits(priv->regmap, MT6370_REG_BL_BSTCTRL,
val, val);
if (ret)
return ret;
/* Common properties */
ret = device_property_read_u32(dev, "max-brightness", &brightness);
if (ret)
brightness = priv->def_max_brightness;
props->max_brightness = min_t(u32, brightness, priv->def_max_brightness);
ret = device_property_read_u32(dev, "default-brightness", &brightness);
if (ret)
brightness = props->max_brightness;
props->brightness = min_t(u32, brightness, props->max_brightness);
val = 0;
if (device_property_read_bool(dev, "mediatek,bled-exponential-mode-enable")) {
val |= MT6370_BL_CODE_MASK;
props->scale = BACKLIGHT_SCALE_NON_LINEAR;
} else
props->scale = BACKLIGHT_SCALE_LINEAR;
ret = device_property_read_u8(dev, "mediatek,bled-channel-use",
&prop_val);
if (ret) {
dev_err(dev, "mediatek,bled-channel-use DT property missing\n");
return ret;
}
if (!prop_val || prop_val > MT6370_BL_MAX_CH) {
dev_err(dev,
"No channel specified or over than upper bound (%d)\n",
prop_val);
return -EINVAL;
}
mask = MT6370_BL_EXT_EN_MASK | MT6370_BL_CH_MASK;
val |= prop_val << MT6370_BL_CH_SHIFT;
if (priv->enable_gpio)
val |= MT6370_BL_EXT_EN_MASK;
return regmap_update_bits(priv->regmap, MT6370_REG_BL_EN, mask, val);
}
static int mt6370_check_vendor_info(struct mt6370_priv *priv)
{
/*
* Because MT6372 uses 14 bits to control the brightness,
* MT6370 and MT6371 use 11 bits. This function is used
* to check the vendor's ID and set the relative hardware
* mask, shift and default maximum brightness value that
* should be used.
*/
unsigned int dev_info, hw_vid, of_vid;
int ret;
ret = regmap_read(priv->regmap, MT6370_REG_DEV_INFO, &dev_info);
if (ret)
return ret;
of_vid = (uintptr_t)device_get_match_data(priv->dev);
hw_vid = FIELD_GET(MT6370_VENID_MASK, dev_info);
hw_vid = (hw_vid == 0x9 || hw_vid == 0xb) ? MT6370_VID_6372 : MT6370_VID_COMMON;
if (hw_vid != of_vid)
return dev_err_probe(priv->dev, -EINVAL,
"Buggy DT, wrong compatible string\n");
if (hw_vid == MT6370_VID_6372) {
priv->dim2_mask = MT6370_BL_DIM2_6372_MASK;
priv->dim2_shift = MT6370_BL_DIM2_6372_SHIFT;
priv->def_max_brightness = MT6370_BL_MAX_6372_BRIGHTNESS;
} else {
priv->dim2_mask = MT6370_BL_DIM2_COMMON_MASK;
priv->dim2_shift = MT6370_BL_DIM2_COMMON_SHIFT;
priv->def_max_brightness = MT6370_BL_MAX_COMMON_BRIGHTNESS;
}
return 0;
}
static int mt6370_bl_probe(struct platform_device *pdev)
{
struct backlight_properties props = {
.type = BACKLIGHT_RAW,
};
struct device *dev = &pdev->dev;
struct mt6370_priv *priv;
int ret;
priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->dev = dev;
priv->regmap = dev_get_regmap(dev->parent, NULL);
if (!priv->regmap)
return dev_err_probe(dev, -ENODEV, "Failed to get regmap\n");
ret = mt6370_check_vendor_info(priv);
if (ret)
return dev_err_probe(dev, ret, "Failed to check vendor info\n");
priv->enable_gpio = devm_gpiod_get_optional(dev, "enable",
GPIOD_OUT_HIGH);
if (IS_ERR(priv->enable_gpio))
return dev_err_probe(dev, PTR_ERR(priv->enable_gpio),
"Failed to get 'enable' gpio\n");
ret = mt6370_init_backlight_properties(priv, &props);
if (ret)
return dev_err_probe(dev, ret,
"Failed to init backlight properties\n");
priv->bl = devm_backlight_device_register(dev, pdev->name, dev, priv,
&mt6370_bl_ops, &props);
if (IS_ERR(priv->bl))
return dev_err_probe(dev, PTR_ERR(priv->bl),
"Failed to register backlight\n");
backlight_update_status(priv->bl);
platform_set_drvdata(pdev, priv);
return 0;
}
static int mt6370_bl_remove(struct platform_device *pdev)
{
struct mt6370_priv *priv = platform_get_drvdata(pdev);
struct backlight_device *bl_dev = priv->bl;
bl_dev->props.brightness = 0;
backlight_update_status(priv->bl);
return 0;
}
static const struct of_device_id mt6370_bl_of_match[] = {
{ .compatible = "mediatek,mt6370-backlight", .data = (void *)MT6370_VID_COMMON },
{ .compatible = "mediatek,mt6372-backlight", .data = (void *)MT6370_VID_6372 },
{}
};
MODULE_DEVICE_TABLE(of, mt6370_bl_of_match);
static struct platform_driver mt6370_bl_driver = {
.driver = {
.name = "mt6370-backlight",
.of_match_table = mt6370_bl_of_match,
},
.probe = mt6370_bl_probe,
.remove = mt6370_bl_remove,
};
module_platform_driver(mt6370_bl_driver);
MODULE_AUTHOR("ChiaEn Wu <chiaen_wu@richtek.com>");
MODULE_DESCRIPTION("MediaTek MT6370 Backlight Driver");
MODULE_LICENSE("GPL v2");