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 15 #include <linux/platform_device.h> 16 #include <linux/io.h> 17 #include <linux/fb.h> 18 #include <linux/backlight.h> 19 20 #include <mach/hardware.h> 21 22 #define EP93XX_RASTER_REG(x) (EP93XX_RASTER_BASE + (x)) 23 #define EP93XX_RASTER_BRIGHTNESS EP93XX_RASTER_REG(0x20) 24 25 #define EP93XX_MAX_COUNT 255 26 #define EP93XX_MAX_BRIGHT 255 27 #define EP93XX_DEF_BRIGHT 128 28 29 struct ep93xxbl { 30 void __iomem *mmio; 31 int brightness; 32 }; 33 34 static int ep93xxbl_set(struct backlight_device *bl, int brightness) 35 { 36 struct ep93xxbl *ep93xxbl = bl_get_data(bl); 37 38 __raw_writel((brightness << 8) | EP93XX_MAX_COUNT, ep93xxbl->mmio); 39 40 ep93xxbl->brightness = brightness; 41 42 return 0; 43 } 44 45 static int ep93xxbl_update_status(struct backlight_device *bl) 46 { 47 int brightness = bl->props.brightness; 48 49 if (bl->props.power != FB_BLANK_UNBLANK || 50 bl->props.fb_blank != FB_BLANK_UNBLANK) 51 brightness = 0; 52 53 return ep93xxbl_set(bl, brightness); 54 } 55 56 static int ep93xxbl_get_brightness(struct backlight_device *bl) 57 { 58 struct ep93xxbl *ep93xxbl = bl_get_data(bl); 59 60 return ep93xxbl->brightness; 61 } 62 63 static const struct backlight_ops ep93xxbl_ops = { 64 .update_status = ep93xxbl_update_status, 65 .get_brightness = ep93xxbl_get_brightness, 66 }; 67 68 static int __init ep93xxbl_probe(struct platform_device *dev) 69 { 70 struct ep93xxbl *ep93xxbl; 71 struct backlight_device *bl; 72 struct backlight_properties props; 73 74 ep93xxbl = devm_kzalloc(&dev->dev, sizeof(*ep93xxbl), GFP_KERNEL); 75 if (!ep93xxbl) 76 return -ENOMEM; 77 78 /* 79 * This register is located in the range already ioremap'ed by 80 * the framebuffer driver. A MFD driver seems a bit of overkill 81 * to handle this so use the static I/O mapping; this address 82 * is already virtual. 83 * 84 * NOTE: No locking is required; the framebuffer does not touch 85 * this register. 86 */ 87 ep93xxbl->mmio = EP93XX_RASTER_BRIGHTNESS; 88 89 memset(&props, 0, sizeof(struct backlight_properties)); 90 props.type = BACKLIGHT_RAW; 91 props.max_brightness = EP93XX_MAX_BRIGHT; 92 bl = backlight_device_register(dev->name, &dev->dev, ep93xxbl, 93 &ep93xxbl_ops, &props); 94 if (IS_ERR(bl)) 95 return PTR_ERR(bl); 96 97 bl->props.brightness = EP93XX_DEF_BRIGHT; 98 99 platform_set_drvdata(dev, bl); 100 101 ep93xxbl_update_status(bl); 102 103 return 0; 104 } 105 106 static int ep93xxbl_remove(struct platform_device *dev) 107 { 108 struct backlight_device *bl = platform_get_drvdata(dev); 109 110 backlight_device_unregister(bl); 111 platform_set_drvdata(dev, NULL); 112 return 0; 113 } 114 115 #ifdef CONFIG_PM 116 static int ep93xxbl_suspend(struct platform_device *dev, pm_message_t state) 117 { 118 struct backlight_device *bl = platform_get_drvdata(dev); 119 120 return ep93xxbl_set(bl, 0); 121 } 122 123 static int ep93xxbl_resume(struct platform_device *dev) 124 { 125 struct backlight_device *bl = platform_get_drvdata(dev); 126 127 backlight_update_status(bl); 128 return 0; 129 } 130 #else 131 #define ep93xxbl_suspend NULL 132 #define ep93xxbl_resume NULL 133 #endif 134 135 static struct platform_driver ep93xxbl_driver = { 136 .driver = { 137 .name = "ep93xx-bl", 138 .owner = THIS_MODULE, 139 }, 140 .probe = ep93xxbl_probe, 141 .remove = __devexit_p(ep93xxbl_remove), 142 .suspend = ep93xxbl_suspend, 143 .resume = ep93xxbl_resume, 144 }; 145 146 static int __init ep93xxbl_init(void) 147 { 148 return platform_driver_register(&ep93xxbl_driver); 149 } 150 module_init(ep93xxbl_init); 151 152 static void __exit ep93xxbl_exit(void) 153 { 154 platform_driver_unregister(&ep93xxbl_driver); 155 } 156 module_exit(ep93xxbl_exit); 157 158 MODULE_DESCRIPTION("EP93xx Backlight Driver"); 159 MODULE_AUTHOR("H Hartley Sweeten <hsweeten@visionengravers.com>"); 160 MODULE_LICENSE("GPL"); 161 MODULE_ALIAS("platform:ep93xx-bl"); 162