[RFC 3/3] leds: Add support for UP board CPLD onboard LEDS

[larry.lai]

The UP boards come with a few FPGA-controlled onboard LEDs:
* UP Board: yellow, green, red
* UP Squared: blue, yellow, green, red

This patch depends on patch "mfd: Add support for UP board CPLD/FPGA".

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: larry.lai <larry.lai@xxxxxxxxxxxxxxx>
---
PATCH V3 -> RFC 2022/11/23: Update the changes Copyright.
PATCH V1 -> V3: There is no change.
PATCH --> PATCH V1: Refer 2022/10/03 Andy Shevchenko review, cleaned up
coding style.
---
 drivers/leds/Kconfig        | 10 +++++
 drivers/leds/Makefile       |  1 +
 drivers/leds/leds-upboard.c | 79 +++++++++++++++++++++++++++++++++++++
 3 files changed, 90 insertions(+)
 create mode 100644 drivers/leds/leds-upboard.c

diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
index 499d0f215a8b..d9d533cb38ca 100644
--- a/drivers/leds/Kconfig
+++ b/drivers/leds/Kconfig
@@ -872,6 +872,16 @@ source "drivers/leds/flash/Kconfig"
 comment "RGB LED drivers"
 source "drivers/leds/rgb/Kconfig"
 
+config LEDS_UPBOARD
+	tristate "LED support for the UP board"
+	depends on LEDS_CLASS
+	depends on MFD_INTEL_UPBOARD_FPGA
+	help
+	  This option enables support for the UP board LEDs.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called leds-upboard.
+
 comment "LED Triggers"
 source "drivers/leds/trigger/Kconfig"
 
diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
index 4fd2f92cd198..e72956645646 100644
--- a/drivers/leds/Makefile
+++ b/drivers/leds/Makefile
@@ -83,6 +83,7 @@ obj-$(CONFIG_LEDS_TI_LMU_COMMON)	+= leds-ti-lmu-common.o
 obj-$(CONFIG_LEDS_TLC591XX)		+= leds-tlc591xx.o
 obj-$(CONFIG_LEDS_TPS6105X)		+= leds-tps6105x.o
 obj-$(CONFIG_LEDS_TURRIS_OMNIA)		+= leds-turris-omnia.o
+obj-$(CONFIG_LEDS_UPBOARD)		+= leds-upboard.o
 obj-$(CONFIG_LEDS_WM831X_STATUS)	+= leds-wm831x-status.o
 obj-$(CONFIG_LEDS_WM8350)		+= leds-wm8350.o
 obj-$(CONFIG_LEDS_WRAP)			+= leds-wrap.o
diff --git a/drivers/leds/leds-upboard.c b/drivers/leds/leds-upboard.c
new file mode 100644
index 000000000000..7a597fdad43c
--- /dev/null
+++ b/drivers/leds/leds-upboard.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * UP Board FPGA-based LED driver
+ *
+ * Copyright (c) 2017, Emutex Ltd. All rights reserved.
+ * Copyright (c) 2022, YunJingTech Ltd.
+ *
+ * Author: Javier Arteaga <javier@xxxxxxxxxx>
+ */
+
+#include <linux/kernel.h>
+#include <linux/leds.h>
+#include <linux/mfd/upboard-fpga.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+struct upboard_led {
+	struct led_classdev cdev;
+	struct regmap_field *field;
+};
+
+static enum led_brightness upboard_led_brightness_get(struct led_classdev *cdev)
+{
+	struct upboard_led *led = container_of(cdev, struct upboard_led, cdev);
+	int brightness = 0;
+
+	regmap_field_read(led->field, &brightness);
+
+	return brightness;
+};
+
+static void upboard_led_brightness_set(struct led_classdev *cdev, enum led_brightness brightness)
+{
+	struct upboard_led *led = container_of(cdev, struct upboard_led, cdev);
+
+	regmap_field_write(led->field, brightness != LED_OFF);
+};
+
+static int __init upboard_led_probe(struct platform_device *pdev)
+{
+	struct upboard_fpga * const up_fpga = dev_get_drvdata(pdev->dev.parent);
+	struct reg_field fldconf = {
+		.reg = UPFPGA_REG_FUNC_EN0,
+	};
+	struct upboard_led_data * const pdata = pdev->dev.platform_data;
+	struct upboard_led *led;
+
+	led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
+	if (!led)
+		return -ENOMEM;
+
+	fldconf.lsb = pdata->bit;
+	fldconf.msb = pdata->bit;
+	led->field = devm_regmap_field_alloc(&pdev->dev, up_fpga->regmap, fldconf);
+	if (IS_ERR(led->field))
+		return PTR_ERR(led->field);
+
+	led->cdev.brightness_get = upboard_led_brightness_get;
+	led->cdev.brightness_set = upboard_led_brightness_set;
+	led->cdev.name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "upboard:%s:",
+					pdata->colour);
+	if (!led->cdev.name)
+		return -ENOMEM;
+
+	return devm_led_classdev_register(&pdev->dev, &led->cdev);
+};
+
+static struct platform_driver upboard_led_driver = {
+	.driver = {
+		.name = "upboard-led",
+	},
+};
+module_platform_driver_probe(upboard_led_driver, upboard_led_probe);
+
+MODULE_AUTHOR("Javier Arteaga <javier@xxxxxxxxxx>");
+MODULE_DESCRIPTION("UP Board LED driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:upboard-led");
-- 
2.17.1