1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Driver for the Cirrus EP93xx lcd backlight 4 * 5 * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com> 6 * 7 * This driver controls the pulse width modulated brightness control output, 8 * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors. 9 */ 10 11 #include <linux/module.h> 12 #include <linux/platform_device.h> 13 #include <linux/io.h> 14 #include <linux/backlight.h> 15 16 #define EP93XX_MAX_COUNT 255 17 #define EP93XX_MAX_BRIGHT 255 18 #define EP93XX_DEF_BRIGHT 128 19 20 struct ep93xxbl { 21 void __iomem *mmio; 22 int brightness; 23 }; 24 25 static int ep93xxbl_set(struct backlight_device *bl, int brightness) 26 { 27 struct ep93xxbl *ep93xxbl = bl_get_data(bl); 28 29 writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio); 30 31 ep93xxbl->brightness = brightness; 32 33 return 0; 34 } 35 36 static int ep93xxbl_update_status(struct backlight_device *bl) 37 { 38 return ep93xxbl_set(bl, backlight_get_brightness(bl)); 39 } 40 41 static int ep93xxbl_get_brightness(struct backlight_device *bl) 42 { 43 struct ep93xxbl *ep93xxbl = bl_get_data(bl); 44 45 return ep93xxbl->brightness; 46 } 47 48 static const struct backlight_ops ep93xxbl_ops = { 49 .update_status = ep93xxbl_update_status, 50 .get_brightness = ep93xxbl_get_brightness, 51 }; 52 53 static int ep93xxbl_probe(struct platform_device *dev) 54 { 55 struct ep93xxbl *ep93xxbl; 56 struct backlight_device *bl; 57 struct backlight_properties props; 58 struct resource *res; 59 60 ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL); 61 if (!ep93xxbl) 62 return -ENOMEM; 63 64 res = platform_get_resource(dev, IORESOURCE_MEM, 0); 65 if (!res) 66 return -ENXIO; 67 68 /* 69 * FIXME - We don't do a request_mem_region here because we are 70 * sharing the register space with the framebuffer driver (see 71 * drivers/video/ep93xx-fb.c) and doing so will cause the second 72 * loaded driver to return -EBUSY. 73 * 74 * NOTE: No locking is required; the framebuffer does not touch 75 * this register. 76 */ 77 ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start, 78 resource_size(res)); 79 if (!ep93xxbl->mmio) 80 return -ENXIO; 81 82 memset(&props, 0, sizeof(struct backlight_properties)); 83 props.type = BACKLIGHT_RAW; 84 props.max_brightness = EP93XX_MAX_BRIGHT; 85 bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev, 86 ep93xxbl, &ep93xxbl_ops, &props); 87 if (IS_ERR(bl)) 88 return PTR_ERR(bl); 89 90 bl->props.brightness = EP93XX_DEF_BRIGHT; 91 92 platform_set_drvdata(dev, bl); 93 94 ep93xxbl_update_status(bl); 95 96 return 0; 97 } 98 99 #ifdef CONFIG_PM_SLEEP 100 static int ep93xxbl_suspend(struct device *dev) 101 { 102 struct backlight_device *bl = dev_get_drvdata(dev); 103 104 return ep93xxbl_set(bl, 0); 105 } 106 107 static int ep93xxbl_resume(struct device *dev) 108 { 109 struct backlight_device *bl = dev_get_drvdata(dev); 110 111 backlight_update_status(bl); 112 return 0; 113 } 114 #endif 115 116 static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume); 117 118 static struct platform_driver ep93xxbl_driver = { 119 .driver = { 120 .name = "ep93xx-bl", 121 .pm = &ep93xxbl_pm_ops, 122 }, 123 .probe = ep93xxbl_probe, 124 }; 125 126 module_platform_driver(ep93xxbl_driver); 127 128 MODULE_DESCRIPTION("EP93xx Backlight Driver"); 129 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>"); 130 MODULE_LICENSE("GPL"); 131 MODULE_ALIAS("platform:ep93xx-bl"); 132