backlight: Add RAVE SP backlight driver

This driver provides access to RAVE SP backlight control
functionality.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Acked-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/video/backlight/Kconfig

@@ -467,6 +467,12 @@ config BACKLIGHT_ARCXCNN
 	  If you have an ARCxCnnnn family backlight say Y to enable
 	  the backlight driver.
 
+config BACKLIGHT_RAVE_SP
+	tristate "RAVE SP Backlight driver"
+	depends on RAVE_SP_CORE
+	help
+	  Support for backlight control on RAVE SP device.
+
 endif # BACKLIGHT_CLASS_DEVICE
 
 endif # BACKLIGHT_LCD_SUPPORT

drivers/video/backlight/Makefile

@@ -57,3 +57,4 @@ obj-$(CONFIG_BACKLIGHT_TOSA)		+= tosa_bl.o
 obj-$(CONFIG_BACKLIGHT_TPS65217)	+= tps65217_bl.o
 obj-$(CONFIG_BACKLIGHT_WM831X)		+= wm831x_bl.o
 obj-$(CONFIG_BACKLIGHT_ARCXCNN) 	+= arcxcnn_bl.o
+obj-$(CONFIG_BACKLIGHT_RAVE_SP)		+= rave-sp-backlight.o

drivers/video/backlight/rave-sp-backlight.c

@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/*
+ * LCD Backlight driver for RAVE SP
+ *
+ * Copyright (C) 2018 Zodiac Inflight Innovations
+ *
+ */
+
+#include <linux/backlight.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mfd/rave-sp.h>
+#include <linux/platform_device.h>
+
+#define	RAVE_SP_BACKLIGHT_LCD_EN	BIT(7)
+
+static int rave_sp_backlight_update_status(struct backlight_device *bd)
+{
+	const struct backlight_properties *p = &bd->props;
+	const u8 intensity =
+		(p->power == FB_BLANK_UNBLANK) ? p->brightness : 0;
+	struct rave_sp *sp = dev_get_drvdata(&bd->dev);
+	u8 cmd[] = {
+		[0] = RAVE_SP_CMD_SET_BACKLIGHT,
+		[1] = 0,
+		[2] = intensity ? RAVE_SP_BACKLIGHT_LCD_EN | intensity : 0,
+		[3] = 0,
+		[4] = 0,
+	};
+
+	return rave_sp_exec(sp, cmd, sizeof(cmd), NULL, 0);
+}
+
+static const struct backlight_ops rave_sp_backlight_ops = {
+	.options	= BL_CORE_SUSPENDRESUME,
+	.update_status	= rave_sp_backlight_update_status,
+};
+
+static struct backlight_properties rave_sp_backlight_props = {
+	.type		= BACKLIGHT_PLATFORM,
+	.max_brightness = 100,
+	.brightness	= 50,
+};
+
+static int rave_sp_backlight_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct backlight_device *bd;
+
+	bd = devm_backlight_device_register(dev, pdev->name, dev->parent,
+					    dev_get_drvdata(dev->parent),
+					    &rave_sp_backlight_ops,
+					    &rave_sp_backlight_props);
+	if (IS_ERR(bd))
+		return PTR_ERR(bd);
+
+	backlight_update_status(bd);
+
+	return 0;
+}
+
+static const struct of_device_id rave_sp_backlight_of_match[] = {
+	{ .compatible = "zii,rave-sp-backlight" },
+	{}
+};
+
+static struct platform_driver rave_sp_backlight_driver = {
+	.probe = rave_sp_backlight_probe,
+	.driver	= {
+		.name = KBUILD_MODNAME,
+		.of_match_table = rave_sp_backlight_of_match,
+	},
+};
+module_platform_driver(rave_sp_backlight_driver);
+
+MODULE_DEVICE_TABLE(of, rave_sp_backlight_of_match);
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Andrey Vostrikov <andrey.vostrikov@cogentembedded.com>");
+MODULE_AUTHOR("Nikita Yushchenko <nikita.yoush@cogentembedded.com>");
+MODULE_AUTHOR("Andrey Smirnov <andrew.smirnov@gmail.com>");
+MODULE_DESCRIPTION("RAVE SP Backlight driver");

include/linux/mfd/rave-sp.h

@@ -21,6 +21,7 @@ enum rave_sp_command {
 	RAVE_SP_CMD_STATUS			= 0xA0,
 	RAVE_SP_CMD_SW_WDT			= 0xA1,
 	RAVE_SP_CMD_PET_WDT			= 0xA2,
+	RAVE_SP_CMD_SET_BACKLIGHT		= 0xA6,
 	RAVE_SP_CMD_RESET			= 0xA7,
 	RAVE_SP_CMD_RESET_REASON		= 0xA8,