87 lines
2.2 KiB
C
87 lines
2.2 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 LM3630A LED driver.
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*/
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#include "hooks.h"
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#include "i2c.h"
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#include "lm3630a.h"
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#include "timer.h"
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/* I2C address */
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#define LM3630A_I2C_ADDR_FLAGS 0x36
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static inline int lm3630a_write(uint8_t reg, uint8_t val)
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{
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return i2c_write8(I2C_PORT_KBLIGHT, LM3630A_I2C_ADDR_FLAGS,
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reg, val);
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}
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static inline int lm3630a_read(uint8_t reg, int *val)
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{
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return i2c_read8(I2C_PORT_KBLIGHT, LM3630A_I2C_ADDR_FLAGS,
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reg, val);
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}
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static void deferred_lm3630a_poweron(void)
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{
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/*
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* Set full brightness so that PWM will control. This needs to happen
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* after setting the control register, because enabling the banks
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* resets the value to 0.
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*/
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lm3630a_write(LM3630A_REG_A_BRIGHTNESS, 0xff);
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}
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DECLARE_DEFERRED(deferred_lm3630a_poweron);
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int lm3630a_poweron(void)
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{
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int ret = 0;
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/*
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* LM3630A will NAK I2C transactions for 1ms (tWAIT in the datasheet)
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* after HWEN asserted or after SW reset.
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*/
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msleep(1);
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/* Sample PWM every 8 periods. */
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ret |= lm3630a_write(LM3630A_REG_FILTER_STRENGTH, 0x3);
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/* Enable feedback and PWM for banks A. */
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ret |= lm3630a_write(LM3630A_REG_CONFIG,
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LM3630A_CFG_BIT_FB_EN_A |
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LM3630A_CFG_BIT_PWM_EN_A);
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/* 24V, 800mA overcurrent protection, 500kHz boost frequency. */
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ret |= lm3630a_write(LM3630A_REG_BOOST_CONTROL,
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LM3630A_BOOST_OVP_24V |
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LM3630A_BOOST_OCP_800MA |
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LM3630A_FMODE_500KHZ);
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/* Limit current to 24.5mA */
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ret |= lm3630a_write(LM3630A_REG_A_CURRENT, 0x1a);
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/* Enable bank A, put in linear mode, and connect LED2 to bank A. */
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ret |= lm3630a_write(LM3630A_REG_CONTROL,
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LM3630A_CTRL_BIT_LINEAR_A |
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LM3630A_CTRL_BIT_LED_EN_A |
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LM3630A_CTRL_BIT_LED2_ON_A);
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/*
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* Only set the brightness after ~100 ms. Without this, LED may blink
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* for a short duration, as the PWM sampler sometimes appears to be
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* confused, and slowly dim from a large initial PWM input value.
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*/
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hook_call_deferred(&deferred_lm3630a_poweron_data, 100 * MSEC);
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return ret;
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}
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int lm3630a_poweroff(void)
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{
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return lm3630a_write(LM3630A_REG_CONTROL, LM3630A_CTRL_BIT_SLEEP_CMD);
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}
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