1 /* 2 * Driver for the Cirrus EP93xx lcd backlight 3 * 4 * Copyright (c) 2010 H Hartley Sweeten <hsweeten@visionengravers.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 * This driver controls the pulse width modulated brightness control output, 11 * BRIGHT, on the Cirrus EP9307, EP9312, and EP9315 processors. 12 */ 13 14 #include <linux/module.h> 15 #include <linux/platform_device.h> 16 #include <linux/io.h> 17 #include <linux/fb.h> 18 #include <linux/backlight.h> 19 20 #define EP93XX_MAX_COUNT 255 21 #define EP93XX_MAX_BRIGHT 255 22 #define EP93XX_DEF_BRIGHT 128 23 24 struct ep93xxbl { 25 void __iomem *mmio; 26 int brightness; 27 }; 28 29 static int ep93xxbl_set(struct backlight_device *bl, int brightness) 30 { 31 struct ep93xxbl *ep93xxbl = bl_get_data(bl); 32 33 writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio); 34 35 ep93xxbl->brightness = brightness; 36 37 return 0; 38 } 39 40 static int ep93xxbl_update_status(struct backlight_device *bl) 41 { 42 int brightness = bl->props.brightness; 43 44 if (bl->props.power != FB_BLANK_UNBLANK || 45 bl->props.fb_blank != FB_BLANK_UNBLANK) 46 brightness = 0; 47 48 return ep93xxbl_set(bl, brightness); 49 } 50 51 static int ep93xxbl_get_brightness(struct backlight_device *bl) 52 { 53 struct ep93xxbl *ep93xxbl = bl_get_data(bl); 54 55 return ep93xxbl->brightness; 56 } 57 58 static const struct backlight_ops ep93xxbl_ops = { 59 .update_status = ep93xxbl_update_status, 60 .get_brightness = ep93xxbl_get_brightness, 61 }; 62 63 static int __init ep93xxbl_probe(struct platform_device *dev) 64 { 65 struct ep93xxbl *ep93xxbl; 66 struct backlight_device *bl; 67 struct backlight_properties props; 68 struct resource *res; 69 70 ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL); 71 if (!ep93xxbl) 72 return -ENOMEM; 73 74 res = platform_get_resource(dev, IORESOURCE_MEM, 0); 75 if (!res) 76 return -ENXIO; 77 78 /* 79 * FIXME - We don't do a request_mem_region here because we are 80 * sharing the register space with the framebuffer driver (see 81 * drivers/video/ep93xx-fb.c) and doing so will cause the second 82 * loaded driver to return -EBUSY. 83 * 84 * NOTE: No locking is required; the framebuffer does not touch 85 * this register. 86 */ 87 ep93xxbl->mmio = devm_ioremap(&dev->dev, res->start, 88 resource_size(res)); 89 if (!ep93xxbl->mmio) 90 return -ENXIO; 91 92 memset(&props, 0, sizeof(struct backlight_properties)); 93 props.type = BACKLIGHT_RAW; 94 props.max_brightness = EP93XX_MAX_BRIGHT; 95 bl = backlight_device_register(dev->name, &dev->dev, ep93xxbl, 96 &ep93xxbl_ops, &props); 97 if (IS_ERR(bl)) 98 return PTR_ERR(bl); 99 100 bl->props.brightness = EP93XX_DEF_BRIGHT; 101 102 platform_set_drvdata(dev, bl); 103 104 ep93xxbl_update_status(bl); 105 106 return 0; 107 } 108 109 static int ep93xxbl_remove(struct platform_device *dev) 110 { 111 struct backlight_device *bl = platform_get_drvdata(dev); 112 113 backlight_device_unregister(bl); 114 platform_set_drvdata(dev, NULL); 115 return 0; 116 } 117 118 #ifdef CONFIG_PM 119 static int ep93xxbl_suspend(struct platform_device *dev, pm_message_t state) 120 { 121 struct backlight_device *bl = platform_get_drvdata(dev); 122 123 return ep93xxbl_set(bl, 0); 124 } 125 126 static int ep93xxbl_resume(struct platform_device *dev) 127 { 128 struct backlight_device *bl = platform_get_drvdata(dev); 129 130 backlight_update_status(bl); 131 return 0; 132 } 133 #else 134 #define ep93xxbl_suspend NULL 135 #define ep93xxbl_resume NULL 136 #endif 137 138 static struct platform_driver ep93xxbl_driver = { 139 .driver = { 140 .name = "ep93xx-bl", 141 .owner = THIS_MODULE, 142 }, 143 .probe = ep93xxbl_probe, 144 .remove = ep93xxbl_remove, 145 .suspend = ep93xxbl_suspend, 146 .resume = ep93xxbl_resume, 147 }; 148 149 module_platform_driver(ep93xxbl_driver); 150 151 MODULE_DESCRIPTION("EP93xx Backlight Driver"); 152 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>"); 153 MODULE_LICENSE("GPL"); 154 MODULE_ALIAS("platform:ep93xx-bl"); 155