86 lines
2.0 KiB
C
86 lines
2.0 KiB
C
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/* Copyright 2018 The Chromium OS Authors. All rights reserved.
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*
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* TI LM3509 LED driver.
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*/
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#include "compile_time_macros.h"
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#include "i2c.h"
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#include "keyboard_backlight.h"
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#include "lm3509.h"
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static inline int lm3509_write(uint8_t reg, uint8_t val)
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{
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return i2c_write8(I2C_PORT_KBLIGHT, LM3509_I2C_ADDR_FLAGS,
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reg, val);
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}
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static inline int lm3509_read(uint8_t reg, int *val)
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{
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return i2c_read8(I2C_PORT_KBLIGHT, LM3509_I2C_ADDR_FLAGS,
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reg, val);
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}
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/* Brightness level (0.0 to 100.0%) to brightness register conversion table */
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static const uint16_t lm3509_brightness[32] = {
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0, 1, 6, 10, 11, 13, 16, 20,
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24, 28, 31, 37, 43, 52, 62, 75,
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87, 100, 125, 150, 168, 187, 225, 262,
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312, 375, 437, 525, 612, 700, 875, 1000
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};
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static int brightness_to_bmain(int percent)
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{
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int i;
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int b = percent * 10;
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for (i = 1; i < sizeof(lm3509_brightness); i++) {
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int low = lm3509_brightness[i - 1];
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int high = lm3509_brightness[i];
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if (high < b)
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continue;
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/* rounding to the nearest */
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return (b - low < high - b) ? i - 1 : i;
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}
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/* Brightness is out of range. Return the highest value. */
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return i - 1;
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}
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static int lm3509_power(int enable)
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{
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/* Enable both MAIN and SUB in unison mode.
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* Don't alter brightness here. It's not driver's business. */
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return lm3509_write(LM3509_REG_GP, enable ? 0x7 : 0);
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}
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static int lm3509_set_brightness(int percent)
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{
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/* We don't need to read/mask/write BMAIN because bit6 and 7 are non
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* functional read only bits.
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*/
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return lm3509_write(LM3509_REG_BMAIN, brightness_to_bmain(percent));
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}
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static int lm3509_get_brightness(void)
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{
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int rv, val;
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rv = lm3509_read(LM3509_REG_BMAIN, &val);
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if (rv)
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return -1;
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val &= LM3509_BMAIN_MASK;
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return lm3509_brightness[val] / 10;
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}
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static int lm3509_init(void)
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{
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return EC_SUCCESS;
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}
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const struct kblight_drv kblight_lm3509 = {
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.init = lm3509_init,
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.set = lm3509_set_brightness,
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.get = lm3509_get_brightness,
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.enable = lm3509_power,
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};
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