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/* Copyright 2018 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* TI LM3630A LED driver.
*/
#include "hooks.h"
#include "i2c.h"
#include "lm3630a.h"
#include "timer.h"
/* I2C address */
#define LM3630A_I2C_ADDR_FLAGS 0x36
static inline int lm3630a_write(uint8_t reg, uint8_t val)
{
return i2c_write8(I2C_PORT_KBLIGHT, LM3630A_I2C_ADDR_FLAGS,
reg, val);
}
static inline int lm3630a_read(uint8_t reg, int *val)
{
return i2c_read8(I2C_PORT_KBLIGHT, LM3630A_I2C_ADDR_FLAGS,
reg, val);
}
static void deferred_lm3630a_poweron(void)
{
/*
* Set full brightness so that PWM will control. This needs to happen
* after setting the control register, because enabling the banks
* resets the value to 0.
*/
lm3630a_write(LM3630A_REG_A_BRIGHTNESS, 0xff);
}
DECLARE_DEFERRED(deferred_lm3630a_poweron);
int lm3630a_poweron(void)
{
int ret = 0;
/*
* LM3630A will NAK I2C transactions for 1ms (tWAIT in the datasheet)
* after HWEN asserted or after SW reset.
*/
msleep(1);
/* Sample PWM every 8 periods. */
ret |= lm3630a_write(LM3630A_REG_FILTER_STRENGTH, 0x3);
/* Enable feedback and PWM for banks A. */
ret |= lm3630a_write(LM3630A_REG_CONFIG,
LM3630A_CFG_BIT_FB_EN_A |
LM3630A_CFG_BIT_PWM_EN_A);
/* 24V, 800mA overcurrent protection, 500kHz boost frequency. */
ret |= lm3630a_write(LM3630A_REG_BOOST_CONTROL,
LM3630A_BOOST_OVP_24V |
LM3630A_BOOST_OCP_800MA |
LM3630A_FMODE_500KHZ);
/* Limit current to 24.5mA */
ret |= lm3630a_write(LM3630A_REG_A_CURRENT, 0x1a);
/* Enable bank A, put in linear mode, and connect LED2 to bank A. */
ret |= lm3630a_write(LM3630A_REG_CONTROL,
LM3630A_CTRL_BIT_LINEAR_A |
LM3630A_CTRL_BIT_LED_EN_A |
LM3630A_CTRL_BIT_LED2_ON_A);
/*
* Only set the brightness after ~100 ms. Without this, LED may blink
* for a short duration, as the PWM sampler sometimes appears to be
* confused, and slowly dim from a large initial PWM input value.
*/
hook_call_deferred(&deferred_lm3630a_poweron_data, 100 * MSEC);
return ret;
}
int lm3630a_poweroff(void)
{
return lm3630a_write(LM3630A_REG_CONTROL, LM3630A_CTRL_BIT_SLEEP_CMD);
}
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