1 /* 2 * Backlight driver for Pandora handheld. 3 * Pandora uses TWL4030 PWM0 -> TPS61161 combo for control backlight. 4 * Based on pwm_bl.c 5 * 6 * Copyright 2009,2012 Gražvydas Ignotas <notasas@gmail.com> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 #include <linux/module.h> 14 #include <linux/kernel.h> 15 #include <linux/platform_device.h> 16 #include <linux/delay.h> 17 #include <linux/fb.h> 18 #include <linux/backlight.h> 19 #include <linux/mfd/twl.h> 20 #include <linux/err.h> 21 22 #define TWL_PWM0_ON 0x00 23 #define TWL_PWM0_OFF 0x01 24 25 #define TWL_INTBR_GPBR1 0x0c 26 #define TWL_INTBR_PMBR1 0x0d 27 28 #define TWL_PMBR1_PWM0_MUXMASK 0x0c 29 #define TWL_PMBR1_PWM0 0x04 30 #define PWM0_CLK_ENABLE BIT(0) 31 #define PWM0_ENABLE BIT(2) 32 33 /* range accepted by hardware */ 34 #define MIN_VALUE 9 35 #define MAX_VALUE 63 36 #define MAX_USER_VALUE (MAX_VALUE - MIN_VALUE) 37 38 #define PANDORABL_WAS_OFF BL_CORE_DRIVER1 39 40 static int pandora_backlight_update_status(struct backlight_device *bl) 41 { 42 int brightness = bl->props.brightness; 43 u8 r; 44 45 if (bl->props.power != FB_BLANK_UNBLANK) 46 brightness = 0; 47 if (bl->props.state & BL_CORE_FBBLANK) 48 brightness = 0; 49 if (bl->props.state & BL_CORE_SUSPENDED) 50 brightness = 0; 51 52 if ((unsigned int)brightness > MAX_USER_VALUE) 53 brightness = MAX_USER_VALUE; 54 55 if (brightness == 0) { 56 if (bl->props.state & PANDORABL_WAS_OFF) 57 goto done; 58 59 /* first disable PWM0 output, then clock */ 60 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1); 61 r &= ~PWM0_ENABLE; 62 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1); 63 r &= ~PWM0_CLK_ENABLE; 64 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1); 65 66 goto done; 67 } 68 69 if (bl->props.state & PANDORABL_WAS_OFF) { 70 /* 71 * set PWM duty cycle to max. TPS61161 seems to use this 72 * to calibrate it's PWM sensitivity when it starts. 73 */ 74 twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF); 75 76 /* first enable clock, then PWM0 out */ 77 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1); 78 r &= ~PWM0_ENABLE; 79 r |= PWM0_CLK_ENABLE; 80 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1); 81 r |= PWM0_ENABLE; 82 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1); 83 84 /* 85 * TI made it very easy to enable digital control, so easy that 86 * it often triggers unintentionally and disabes PWM control, 87 * so wait until 1 wire mode detection window ends. 88 */ 89 usleep_range(2000, 10000); 90 } 91 92 twl_i2c_write_u8(TWL_MODULE_PWM, MIN_VALUE + brightness, TWL_PWM0_OFF); 93 94 done: 95 if (brightness != 0) 96 bl->props.state &= ~PANDORABL_WAS_OFF; 97 else 98 bl->props.state |= PANDORABL_WAS_OFF; 99 100 return 0; 101 } 102 103 static const struct backlight_ops pandora_backlight_ops = { 104 .options = BL_CORE_SUSPENDRESUME, 105 .update_status = pandora_backlight_update_status, 106 }; 107 108 static int pandora_backlight_probe(struct platform_device *pdev) 109 { 110 struct backlight_properties props; 111 struct backlight_device *bl; 112 u8 r; 113 114 memset(&props, 0, sizeof(props)); 115 props.max_brightness = MAX_USER_VALUE; 116 props.type = BACKLIGHT_RAW; 117 bl = devm_backlight_device_register(&pdev->dev, pdev->name, &pdev->dev, 118 NULL, &pandora_backlight_ops, &props); 119 if (IS_ERR(bl)) { 120 dev_err(&pdev->dev, "failed to register backlight\n"); 121 return PTR_ERR(bl); 122 } 123 124 platform_set_drvdata(pdev, bl); 125 126 /* 64 cycle period, ON position 0 */ 127 twl_i2c_write_u8(TWL_MODULE_PWM, 0x80, TWL_PWM0_ON); 128 129 bl->props.state |= PANDORABL_WAS_OFF; 130 bl->props.brightness = MAX_USER_VALUE; 131 backlight_update_status(bl); 132 133 /* enable PWM function in pin mux */ 134 twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_PMBR1); 135 r &= ~TWL_PMBR1_PWM0_MUXMASK; 136 r |= TWL_PMBR1_PWM0; 137 twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_PMBR1); 138 139 return 0; 140 } 141 142 static struct platform_driver pandora_backlight_driver = { 143 .driver = { 144 .name = "pandora-backlight", 145 }, 146 .probe = pandora_backlight_probe, 147 }; 148 149 module_platform_driver(pandora_backlight_driver); 150 151 MODULE_AUTHOR("Gražvydas Ignotas <notasas@gmail.com>"); 152 MODULE_DESCRIPTION("Pandora Backlight Driver"); 153 MODULE_LICENSE("GPL"); 154 MODULE_ALIAS("platform:pandora-backlight"); 155