system76-coreboot/src/drivers/i2c/rx6110sa/rx6110sa.c

/*
 * This file is part of the coreboot project.
 *
 * Copyright 2017 Siemens AG.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <device/i2c_bus.h>
#include <device/device.h>
#include <version.h>
#include <console/console.h>
#include <bcd.h>
#include <timer.h>
#include "chip.h"
#include "rx6110sa.h"

/* Function to write a register in the RTC with the given value. */
static void rx6110sa_write(struct device *dev, uint8_t reg, uint8_t val)
{
	i2c_writeb_at(dev, reg, val);
}

/* Function to read a register in the RTC. */
static uint8_t rx6110sa_read(struct device *dev, uint8_t reg)
{
	return (uint8_t)i2c_readb_at(dev, reg);
}

/* Set RTC date from coreboot build date. */
static void rx6110sa_set_build_date(struct device *dev)
{
	rx6110sa_write(dev, YEAR_REG, coreboot_build_date.year);
	rx6110sa_write(dev, MONTH_REG, coreboot_build_date.month);
	rx6110sa_write(dev, DAY_REG, coreboot_build_date.day);
	rx6110sa_write(dev, WEEK_REG, (1 << coreboot_build_date.weekday));
}

/* Set RTC date from user defined date (available in e.g. device tree). */
static void rx6110sa_set_user_date(struct device *dev)
{
	struct drivers_i2c_rx6110sa_config *config = dev->chip_info;

	rx6110sa_write(dev, YEAR_REG, bin2bcd(config->user_year));
	rx6110sa_write(dev, MONTH_REG, bin2bcd(config->user_month));
	rx6110sa_write(dev, DAY_REG, bin2bcd(config->user_day));
	rx6110sa_write(dev, WEEK_REG, (1 << config->user_weekday));
}

static void rx6110sa_final(struct device *dev)
{
	uint8_t hour, minute, second, year, month, day;

	/* Read back current RTC date and time and print it to the console. */
	hour = rx6110sa_read(dev, HOUR_REG);
	minute = rx6110sa_read(dev, MINUTE_REG);
	second = rx6110sa_read(dev, SECOND_REG);
	year = rx6110sa_read(dev, YEAR_REG);
	month = rx6110sa_read(dev, MONTH_REG);
	day = rx6110sa_read(dev, DAY_REG);

	printk(BIOS_INFO, "%s: Current date %02d.%02d.%02d %02d:%02d:%02d\n",
		dev->chip_ops->name, bcd2bin(month), bcd2bin(day),
		bcd2bin(year), bcd2bin(hour), bcd2bin(minute), bcd2bin(second));
}

static void rx6110sa_init(struct device *dev)
{
	struct drivers_i2c_rx6110sa_config *config = dev->chip_info;
	uint8_t reg, flags;
	struct stopwatch sw;

	/* Do a dummy read first as requested in the datasheet. */
	rx6110sa_read(dev, SECOND_REG);
	/* Check power loss status by reading the VLF-bit. */
	flags = rx6110sa_read(dev, FLAG_REGISTER);
	if (flags & VLF_BIT) {
		/*
		 * Voltage low detected, perform RX6110 SA reset sequence as
		 * requested in the datasheet. The meaning of the registers 0x60
		 * and above is not documented in the datasheet, they have to be
		 * used as requested according to Epson.
		 */
		rx6110sa_write(dev, BATTERY_BACKUP_REG, 0x00);
		rx6110sa_write(dev, CTRL_REG, 0x00);
		rx6110sa_write(dev, CTRL_REG, TEST_BIT);
		rx6110sa_write(dev, 0x60, 0xd3);
		rx6110sa_write(dev, 0x66, 0x03);
		rx6110sa_write(dev, 0x6b, 0x02);
		rx6110sa_write(dev, 0x6b, 0x01);
		/* According to the datasheet one have to wait for at least 2 ms
		 * before the VLF bit can be cleared in the flag register after
		 * this reset sequence. As the other registers are still
		 * accessible use the stopwatch to parallel the flow.
		 */
		stopwatch_init_msecs_expire(&sw, AFTER_RESET_DELAY_MS);
	}
	/*
	 * Set up important registers even if there was no power loss to make
	 * sure that the right mode is used as it directly influences the
	 * backup current consumption and therefore the backup time. These
	 * settings do not change current date and time and the RTC will not
	 * be stopped while the registers are set up.
	 */
	reg = (config->pmon_sampling & PMON_SAMPL_MASK) |
		(!!config->bks_off << 2) | (!!config->bks_on << 3) |
		(!!config->iocut_en << 4);
	rx6110sa_write(dev, BATTERY_BACKUP_REG, reg);

	/* Clear timer enable bit and set frequency of clock output. */
	reg = rx6110sa_read(dev, EXTENSION_REG);
	reg &= ~(FSEL_MASK);
	reg |= ((config->cof_selection << 6) & FSEL_MASK);
	if (config->timer_preset) {
		/* Timer needs to be in stop mode prior to programming it. */
		if (reg & TE_BIT) {
			reg &= ~TE_BIT;
			rx6110sa_write(dev, EXTENSION_REG, reg);
		}
		/* Program the timer preset value. */
		rx6110sa_write(dev, TMR_COUNTER_0_REG,
				config->timer_preset & 0xff);
		rx6110sa_write(dev, TMR_COUNTER_1_REG,
				(config->timer_preset >> 8) & 0xff);
		/* Set Timer Enable bit and the timer clock value. */
		reg &= ~TSEL_MASK;
		reg |= ((!!config->timer_en << 4) |
			(config->timer_clk & TSEL_MASK));
	}
	rx6110sa_write(dev, EXTENSION_REG, reg);
	rx6110sa_write(dev, CTRL_REG, 0x00);
	rx6110sa_write(dev, DIGITAL_REG, 0x00);
	rx6110sa_write(dev, RESERVED_BIT_REG, RTC_INIT_VALUE);
	reg = (!!config->enable_1hz_out << 4) |
		(!!config->irq_output_pin << 2) |
		(config->fout_output_pin & FOUT_OUTPUT_PIN_MASK);
	rx6110sa_write(dev, IRQ_CONTROL_REG, reg);
	/* If there was no power loss event no further steps are needed. */
	if (!(flags & VLF_BIT))
		return;
	/* There was a power loss event, clear voltage low detect bit.
	 * Take the needed delay after a reset sequence into account before the
	 * VLF-bit can be cleared.
	 */
	stopwatch_wait_until_expired(&sw);
	flags &= ~VLF_BIT;
	rx6110sa_write(dev, FLAG_REGISTER, flags);

	/* Before setting the clock stop oscillator. */
	rx6110sa_write(dev, CTRL_REG, STOP_BIT);

	if (config->set_user_date) {
		/* Set user date defined in device tree. */
		printk(BIOS_DEBUG, "%s: Set to user date\n",
				dev->chip_ops->name);
		rx6110sa_set_user_date(dev);
	} else {
		/* Set date from coreboot build. */
		printk(BIOS_DEBUG, "%s: Set to coreboot build date\n",
				dev->chip_ops->name);
		rx6110sa_set_build_date(dev);
	}
	rx6110sa_write(dev, HOUR_REG, 1);
	rx6110sa_write(dev, MINUTE_REG, 0);
	rx6110sa_write(dev, SECOND_REG, 0);
	/* Start oscillator again as the RTC is set up now. */
	reg = (!!config->timer_irq_en << 4) |
		(config->timer_mode & TMR_MODE_MASK);
	rx6110sa_write(dev, CTRL_REG, reg);
}

static struct device_operations rx6110sa_ops = {
	.read_resources		= DEVICE_NOOP,
	.set_resources		= DEVICE_NOOP,
	.enable_resources	= DEVICE_NOOP,
	.init			= rx6110sa_init,
	.final			= rx6110sa_final
};

static void rx6110sa_enable(struct device *dev)
{
	dev->ops = &rx6110sa_ops;
}

struct chip_operations drivers_i2c_rx6110sa_ops = {
	CHIP_NAME("RX6110 SA")
	.enable_dev = rx6110sa_enable
};