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// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/**
* rtc-rpi.c
*
* RTC driver using firmware mailbox
* Supports battery backed RTC and wake alarms
*
* Based on rtc-meson-vrtc by Neil Armstrong
*
* Copyright (c) 2023, Raspberry Pi Ltd.
*/
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/of.h>
#include <soc/bcm2835/raspberrypi-firmware.h>
struct rpi_rtc_data {
struct rtc_device *rtc;
struct rpi_firmware *fw;
u32 bbat_vchg_microvolts;
};
#define RPI_FIRMWARE_GET_RTC_REG 0x00030087
#define RPI_FIRMWARE_SET_RTC_REG 0x00038087
enum {
RTC_TIME,
RTC_ALARM,
RTC_ALARM_PENDING,
RTC_ALARM_ENABLE,
RTC_BBAT_CHG_VOLTS,
RTC_BBAT_CHG_VOLTS_MIN,
RTC_BBAT_CHG_VOLTS_MAX,
RTC_BBAT_VOLTS
};
static int rpi_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev);
u32 data[2] = {RTC_TIME};
int err;
err = rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
rtc_time64_to_tm(data[1], tm);
return err;
}
static int rpi_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev);
u32 data[2] = {RTC_TIME, rtc_tm_to_time64(tm)};
return rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_SET_RTC_REG,
&data, sizeof(data));
}
static int rpi_rtc_alarm_irq_is_enabled(struct device *dev, unsigned char *enabled)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev);
u32 data[2] = {RTC_ALARM_ENABLE};
s32 err = 0;
err = rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
*enabled = data[1] & 0x1;
return err;
}
static int rpi_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev);
u32 data[2] = {RTC_ALARM_ENABLE, enabled};
return rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_SET_RTC_REG,
&data, sizeof(data));
}
static int rpi_rtc_alarm_clear_pending(struct device *dev)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev);
u32 data[2] = {RTC_ALARM_PENDING, 1};
return rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_SET_RTC_REG,
&data, sizeof(data));
}
static int rpi_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev);
u32 data[2] = {RTC_ALARM};
s32 err = 0;
err = rpi_rtc_alarm_irq_is_enabled(dev, &alarm->enabled);
if (!err)
err = rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
rtc_time64_to_tm(data[1], &alarm->time);
return err;
}
static int rpi_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev);
u32 data[2] = {RTC_ALARM, rtc_tm_to_time64(&alarm->time)};
int err;
err = rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_SET_RTC_REG,
&data, sizeof(data));
if (err == 0)
err = rpi_rtc_alarm_irq_enable(dev, alarm->enabled);
return err;
}
static const struct rtc_class_ops rpi_rtc_ops = {
.read_time = rpi_rtc_read_time,
.set_time = rpi_rtc_set_time,
.read_alarm = rpi_rtc_read_alarm,
.set_alarm = rpi_rtc_set_alarm,
.alarm_irq_enable = rpi_rtc_alarm_irq_enable,
};
static int rpi_rtc_set_charge_voltage(struct device *dev)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev);
u32 data[2] = {RTC_BBAT_CHG_VOLTS, vrtc->bbat_vchg_microvolts};
int err;
err = rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_SET_RTC_REG,
&data, sizeof(data));
if (err)
dev_err(dev, "failed to set trickle charge voltage to %uuV: %d\n",
vrtc->bbat_vchg_microvolts, err);
else if (vrtc->bbat_vchg_microvolts)
dev_info(dev, "trickle charging enabled at %uuV\n",
vrtc->bbat_vchg_microvolts);
return err;
}
static ssize_t rpi_rtc_print_uint_reg(struct device *dev, char *buf, u32 reg)
{
struct rpi_rtc_data *vrtc = dev_get_drvdata(dev->parent);
u32 data[2] = {reg, 0};
int ret = 0;
ret = rpi_firmware_property(vrtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
if (ret < 0)
return ret;
return sprintf(buf, "%u\n", data[1]);
}
static ssize_t charging_voltage_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return rpi_rtc_print_uint_reg(dev, buf, RTC_BBAT_CHG_VOLTS);
}
static DEVICE_ATTR_RO(charging_voltage);
static ssize_t charging_voltage_min_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return rpi_rtc_print_uint_reg(dev, buf, RTC_BBAT_CHG_VOLTS_MIN);
}
static DEVICE_ATTR_RO(charging_voltage_min);
static ssize_t charging_voltage_max_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return rpi_rtc_print_uint_reg(dev, buf, RTC_BBAT_CHG_VOLTS_MAX);
}
static DEVICE_ATTR_RO(charging_voltage_max);
static ssize_t battery_voltage_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
return rpi_rtc_print_uint_reg(dev, buf, RTC_BBAT_VOLTS);
}
static DEVICE_ATTR_RO(battery_voltage);
static struct attribute *rpi_rtc_attrs[] = {
&dev_attr_charging_voltage.attr,
&dev_attr_charging_voltage_min.attr,
&dev_attr_charging_voltage_max.attr,
&dev_attr_battery_voltage.attr,
NULL
};
static const struct attribute_group rpi_rtc_sysfs_files = {
.attrs = rpi_rtc_attrs,
};
static int rpi_rtc_probe(struct platform_device *pdev)
{
struct rpi_rtc_data *vrtc;
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
struct device_node *fw_node;
struct rpi_firmware *fw;
int ret;
fw_node = of_parse_phandle(np, "firmware", 0);
if (!fw_node) {
dev_err(dev, "Missing firmware node\n");
return -ENOENT;
}
fw = rpi_firmware_get(fw_node);
if (!fw)
return -EPROBE_DEFER;
vrtc = devm_kzalloc(&pdev->dev, sizeof(*vrtc), GFP_KERNEL);
if (!vrtc)
return -ENOMEM;
vrtc->fw = fw;
device_init_wakeup(&pdev->dev, 1);
platform_set_drvdata(pdev, vrtc);
vrtc->rtc = devm_rtc_allocate_device(&pdev->dev);
if (IS_ERR(vrtc->rtc))
return PTR_ERR(vrtc->rtc);
set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, vrtc->rtc->features);
clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, vrtc->rtc->features);
vrtc->rtc->ops = &rpi_rtc_ops;
ret = rtc_add_group(vrtc->rtc, &rpi_rtc_sysfs_files);
if (ret)
return ret;
rpi_rtc_alarm_clear_pending(dev);
/*
* Optionally enable trickle charging - if the property isn't
* present (or set to zero), trickle charging is disabled.
*/
of_property_read_u32(np, "trickle-charge-microvolt",
&vrtc->bbat_vchg_microvolts);
rpi_rtc_set_charge_voltage(dev);
return devm_rtc_register_device(vrtc->rtc);
}
static const struct of_device_id rpi_rtc_dt_match[] = {
{ .compatible = "raspberrypi,rpi-rtc"},
{},
};
MODULE_DEVICE_TABLE(of, rpi_rtc_dt_match);
static struct platform_driver rpi_rtc_driver = {
.probe = rpi_rtc_probe,
.driver = {
.name = "rpi-rtc",
.of_match_table = rpi_rtc_dt_match,
},
};
module_platform_driver(rpi_rtc_driver);
MODULE_DESCRIPTION("Raspberry Pi RTC driver");
MODULE_LICENSE("GPL");
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