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// SPDX-License-Identifier: GPL-2.0 OR BSD-3-Clause
/**
* rtc-raspberrypi.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>
#define RTC_TIME 0
#define RTC_ALARM 1
#define RTC_ALARM_PENDING 2
#define RTC_ALARM_ENABLE 3
#define RTC_BBAT_CHG_VOLTS 4
#define RTC_BBAT_CHG_VOLTS_MIN 5
#define RTC_BBAT_CHG_VOLTS_MAX 6
#define RTC_BBAT_VOLTS 7
struct rpi_rtc_data {
struct rtc_device *rtc;
struct rpi_firmware *fw;
u32 bbat_vchg_millivolts;
u32 bbat_vchg_min_millivolts;
u32 bbat_vchg_max_millivolts;
};
struct rpi_rtc_reg {
__le32 reg;
__le32 val;
} __packed;
static int rpi_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
struct rpi_rtc_data *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_TIME)
};
int err;
err = rpi_firmware_property(rtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
rtc_time64_to_tm(le32_to_cpu(data.val), tm);
return err;
}
static int rpi_rtc_set_time(struct device *dev, struct rtc_time *tm)
{
struct rpi_rtc_data *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_TIME),
.val = cpu_to_le32(rtc_tm_to_time64(tm))
};
return rpi_firmware_property(rtc->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 *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_ALARM_ENABLE)
};
int err;
err = rpi_firmware_property(rtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
*enabled = le32_to_cpu(data.val) & 0x1;
return err;
}
static int rpi_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
{
struct rpi_rtc_data *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_ALARM_ENABLE),
.val = cpu_to_le32(enabled)
};
return rpi_firmware_property(rtc->fw, RPI_FIRMWARE_SET_RTC_REG,
&data, sizeof(data));
}
static int rpi_rtc_alarm_clear_pending(struct device *dev)
{
struct rpi_rtc_data *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_ALARM_PENDING),
.val = cpu_to_le32(1)
};
return rpi_firmware_property(rtc->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 *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_ALARM)
};
int err;
err = rpi_rtc_alarm_irq_is_enabled(dev, &alarm->enabled);
if (!err)
err = rpi_firmware_property(rtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
rtc_time64_to_tm(le32_to_cpu(data.val), &alarm->time);
return err;
}
static int rpi_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
{
struct rpi_rtc_data *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_ALARM),
.val = cpu_to_le32(rtc_tm_to_time64(&alarm->time))
};
int err;
err = rpi_rtc_alarm_clear_pending(dev);
if (!err)
err = rpi_firmware_property(rtc->fw, RPI_FIRMWARE_SET_RTC_REG,
&data, sizeof(data));
if (!err)
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 void rpi_rtc_set_limits(struct device *dev)
{
struct rpi_rtc_data *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_BBAT_CHG_VOLTS_MIN)
};
int err = rpi_firmware_property(rtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
if (!err)
rtc->bbat_vchg_min_millivolts = le32_to_cpu(data.val) / 1000U;
else
dev_warn(dev, "failed to get minimum trickle charge voltage\n");
data.reg = cpu_to_le32(RTC_BBAT_CHG_VOLTS_MAX);
data.val = cpu_to_le32(0);
err = rpi_firmware_property(rtc->fw, RPI_FIRMWARE_GET_RTC_REG,
&data, sizeof(data));
if (!err)
rtc->bbat_vchg_max_millivolts = le32_to_cpu(data.val) / 1000U;
else
dev_warn(dev, "failed to get maximum trickle charge voltage\n");
}
static void rpi_rtc_set_charge_voltage(struct device *dev)
{
struct rpi_rtc_data *rtc = dev_get_drvdata(dev);
struct rpi_rtc_reg data = {
.reg = cpu_to_le32(RTC_BBAT_CHG_VOLTS),
.val = cpu_to_le32(rtc->bbat_vchg_millivolts * 1000U)
};
int err;
if (rtc->bbat_vchg_millivolts != 0 &&
(rtc->bbat_vchg_millivolts < rtc->bbat_vchg_min_millivolts ||
rtc->bbat_vchg_millivolts > rtc->bbat_vchg_max_millivolts)) {
dev_warn(dev, "trickle charge voltage %umV is outside of the supported range (%umV - %umV)\n",
rtc->bbat_vchg_millivolts,
rtc->bbat_vchg_min_millivolts,
rtc->bbat_vchg_max_millivolts);
return;
}
err = rpi_firmware_property(rtc->fw, RPI_FIRMWARE_SET_RTC_REG,
&data, sizeof(data));
if (err)
dev_err(dev, "failed to set trickle charge voltage to %umV: %d\n",
rtc->bbat_vchg_millivolts, err);
else if (rtc->bbat_vchg_millivolts)
dev_info(dev, "trickle charging enabled at %umV\n",
rtc->bbat_vchg_millivolts);
}
static int rpi_rtc_probe(struct platform_device *pdev)
{
struct rpi_rtc_data *rtc;
struct device *dev = &pdev->dev;
struct rpi_firmware *firmware;
int ret;
// Get the firmware device from the parent device
firmware = devm_rpi_firmware_get(dev, dev->parent->of_node);
if (!firmware)
return -EPROBE_DEFER;
rtc = devm_kzalloc(dev, sizeof(*rtc), GFP_KERNEL);
if (!rtc)
return -ENOMEM;
rtc->fw = firmware;
ret = devm_device_init_wakeup(dev);
if (ret)
return ret;
platform_set_drvdata(pdev, rtc);
rtc->rtc = devm_rtc_allocate_device(dev);
if (IS_ERR(rtc->rtc))
return PTR_ERR(rtc->rtc);
rtc->rtc->range_max = U32_MAX; /* 2106-02-07 */
set_bit(RTC_FEATURE_ALARM_WAKEUP_ONLY, rtc->rtc->features);
clear_bit(RTC_FEATURE_UPDATE_INTERRUPT, rtc->rtc->features);
rtc->rtc->ops = &rpi_rtc_ops;
rpi_rtc_alarm_clear_pending(dev);
/*
* The trickle-voltage property lives on the parent firmware node
* because we deliberately do not create a DT child node just to
* instantiate this driver (see DT maintainer guidance).
* The firmware driver registers us as a platform device at runtime.
*/
rtc->bbat_vchg_millivolts = 0;
of_property_read_u32(dev->parent->of_node, "trickle-voltage-millivolt",
&rtc->bbat_vchg_millivolts);
rpi_rtc_set_limits(dev);
rpi_rtc_set_charge_voltage(dev);
return devm_rtc_register_device(rtc->rtc);
}
static const struct platform_device_id raspberrypi_rtc_id[] = {
{ "raspberrypi-rtc" },
{ }
};
MODULE_DEVICE_TABLE(platform, raspberrypi_rtc_id);
static struct platform_driver rpi_rtc_driver = {
.driver = {
.name = "raspberrypi-rtc",
},
.id_table = raspberrypi_rtc_id,
.probe = rpi_rtc_probe
};
module_platform_driver(rpi_rtc_driver);
MODULE_AUTHOR("Jonathan Bell <jonathan@raspberrypi.com>");
MODULE_AUTHOR("Sander Speetjens <sander.speetjens@gmail.com>");
MODULE_DESCRIPTION("Raspberry Pi RTC driver");
MODULE_LICENSE("Dual BSD/GPL");
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