diff options
Diffstat (limited to 'drivers/rtc/rtc-rpi.c')
| -rw-r--r-- | drivers/rtc/rtc-rpi.c | 277 |
1 files changed, 277 insertions, 0 deletions
diff --git a/drivers/rtc/rtc-rpi.c b/drivers/rtc/rtc-rpi.c new file mode 100644 index 000000000000..006012333e78 --- /dev/null +++ b/drivers/rtc/rtc-rpi.c @@ -0,0 +1,277 @@ +// 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"); |