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/fb.h> 15 #include <linux/backlight.h> 16 17 #define EP93XX_MAX_COUNT 255 18 #define EP93XX_MAX_BRIGHT 255 19 #define EP93XX_DEF_BRIGHT 128 20 21 struct ep93xxbl { 22 void __iomem *mmio; 23 int brightness; 24 }; 25 26 static int ep93xxbl_set(struct backlight_device *bl, int brightness) 27 { 28 struct ep93xxbl *ep93xxbl = bl_get_data(bl); 29 30 writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio); 31 32 ep93xxbl->brightness = brightness; 33 34 return 0; 35 } 36 37 static int ep93xxbl_update_status(struct backlight_device *bl) 38 { 39 return ep93xxbl_set(bl, backlight_get_brightness(bl)); 40 } 41 42 static int ep93xxbl_get_brightness(struct backlight_device *bl) 43 { 44 struct ep93xxbl *ep93xxbl = bl_get_data(bl); 45 46 return ep93xxbl->brightness; 47 } 48 49 static const struct backlight_ops ep93xxbl_ops = { 50 .update_status = ep93xxbl_update_status, 51 .get_brightness = ep93xxbl_get_brightness, 52 }; 53 54 static int ep93xxbl_probe(struct platform_device *dev) 55 { 56 struct ep93xxbl *ep93xxbl; 57 struct backlight_device *bl; 58 struct backlight_properties props; 59 struct resource *res; 60 61 ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL); 62 if (!ep93xxbl) 63 return -ENOMEM; 64 65 res = platform_get_resource(dev, IORESOURCE_MEM, 0); 66 if (!res) 67 return -ENXIO; 68 69 /* 70 * FIXME - We don't do a request_mem_region here because we are 71 * sharing the register space with the framebuffer driver (see 72 * drivers/video/ep93xx-fb.c) and doing so will cause the second 73 * loaded driver to return -EBUSY. 74 * 75 * NOTE: No locking is required; the framebuffer does not touch 76 * this register. 77 */ 78 ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start, 79 resource_size(res)); 80 if (!ep93xxbl->mmio) 81 return -ENXIO; 82 83 memset(&props, 0, sizeof(struct backlight_properties)); 84 props.type = BACKLIGHT_RAW; 85 props.max_brightness = EP93XX_MAX_BRIGHT; 86 bl = devm_backlight_device_register(&dev->dev, dev->name, &dev->dev, 87 ep93xxbl, &ep93xxbl_ops, &props); 88 if (IS_ERR(bl)) 89 return PTR_ERR(bl); 90 91 bl->props.brightness = EP93XX_DEF_BRIGHT; 92 93 platform_set_drvdata(dev, bl); 94 95 ep93xxbl_update_status(bl); 96 97 return 0; 98 } 99 100 #ifdef CONFIG_PM_SLEEP 101 static int ep93xxbl_suspend(struct device *dev) 102 { 103 struct backlight_device *bl = dev_get_drvdata(dev); 104 105 return ep93xxbl_set(bl, 0); 106 } 107 108 static int ep93xxbl_resume(struct device *dev) 109 { 110 struct backlight_device *bl = dev_get_drvdata(dev); 111 112 backlight_update_status(bl); 113 return 0; 114 } 115 #endif 116 117 static SIMPLE_DEV_PM_OPS(ep93xxbl_pm_ops, ep93xxbl_suspend, ep93xxbl_resume); 118 119 static struct platform_driver ep93xxbl_driver = { 120 .driver = { 121 .name = "ep93xx-bl", 122 .pm = &ep93xxbl_pm_ops, 123 }, 124 .probe = ep93xxbl_probe, 125 }; 126 127 module_platform_driver(ep93xxbl_driver); 128 129 MODULE_DESCRIPTION("EP93xx Backlight Driver"); 130 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>"); 131 MODULE_LICENSE("GPL"); 132 MODULE_ALIAS("platform:ep93xx-bl"); 133