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[212.71.14.70]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4870bf27ce2sm15276567f8f.20.2026.09.17.05.25.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Sep 2026 05:25:15 -0700 (PDT) From: Sander Speetjens To: Alexandre Belloni Cc: Rob Herring , Krzysztof Kozlowski , Conor Dooley , Florian Fainelli , Jonathan Bell , Stefan Wahren , linux-rtc@vger.kernel.org, devicetree@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org, sander.speetjens@gmail.com, Dom Cobley Subject: [PATCH v2 2/2] rtc: Add Raspberry Pi 5 RTC driver Date: Thu, 17 Sep 2026 14:21:44 +0200 Message-ID: <20260917122144.703221-3-sander.speetjens@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260917122144.703221-1-sander.speetjens@gmail.com> References: <20260917122144.703221-1-sander.speetjens@gmail.com> Precedence: bulk X-Mailing-List: linux-rtc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Upstreaming the downstream Raspberry Pi 5 RTC driver. This driver supports the custom DA9091, which is accessed through the firmware mailbox. V1 -> V2: Instead of the original driver, which was directly bound to the device tree. This driver is bound to the Raspberry Pi firmware device by creating a child device in the firmware driver probe function. The child device is then bound to this driver, which uses the firmware mailbox to access the RTC. A couple of minor changes have been made to the driver since it was originally written, including: - Checking if the model is a Raspberry Pi 5, as the RTC is only present on that model. - Using the new devm_rpi_firmware_get() and devm_init_wakeup() helper to get the firmware device and avoid leaking memory. - Using millivolts instead of microvolts for the trickle charge voltage, to match the RTC standard. - Instead of setting the trickle charge voltage to 0 to disable trickle charging, the property is now optional. If the property is not present, trickle charging is disabled, per the RTC standard. - Renaming the driver dt match compatible to "raspberrypi,firmware-rtc" to match the other firmware bindings. - Renaming the driver name to "raspberrypi-rtc" to match the other firmware drivers. Signed-off-by: Jonathan Bell Signed-off-by: Dom Cobley Signed-off-by: Sander Speetjens --- drivers/firmware/raspberrypi.c | 19 +++ drivers/rtc/Kconfig | 11 ++ drivers/rtc/Makefile | 1 + drivers/rtc/rtc-raspberrypi.c | 277 +++++++++++++++++++++++++++++++++ 4 files changed, 308 insertions(+) create mode 100644 drivers/rtc/rtc-raspberrypi.c diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c index 0aa322e9a2e7..b284c689f782 100644 --- a/drivers/firmware/raspberrypi.c +++ b/drivers/firmware/raspberrypi.c @@ -24,6 +24,7 @@ static struct platform_device *rpi_hwmon; static struct platform_device *rpi_clk; +static struct platform_device *rpi_rtc; struct rpi_firmware { struct mbox_client cl; @@ -231,6 +232,21 @@ static void rpi_register_clk_driver(struct device *dev) -1, NULL, 0); } +static void rpi_register_rtc_driver(struct device *dev) +{ + struct device_node *firmware; + + firmware = of_get_compatible_child(dev->of_node, + "raspberrypi,firmware-rtc"); + if (firmware) { + of_node_put(firmware); + return; + } + + rpi_rtc = platform_device_register_data(dev, "raspberrypi-rtc", + -1, NULL, 0); +} + unsigned int rpi_firmware_clk_get_max_rate(struct rpi_firmware *fw, unsigned int id) { struct rpi_firmware_clk_rate_request msg = @@ -305,6 +321,7 @@ static int rpi_firmware_probe(struct platform_device *pdev) rpi_firmware_print_firmware_revision(fw); rpi_register_hwmon_driver(dev, fw); rpi_register_clk_driver(dev); + rpi_register_rtc_driver(dev); return 0; } @@ -327,6 +344,8 @@ static void rpi_firmware_remove(struct platform_device *pdev) rpi_hwmon = NULL; platform_device_unregister(rpi_clk); rpi_clk = NULL; + platform_device_unregister(rpi_rtc); + rpi_rtc = NULL; rpi_firmware_put(fw); } diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index 05b9233b9418..382973d46e06 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -1999,6 +1999,17 @@ config RTC_DRV_R7301 This driver can also be built as a module. If so, the module will be called rtc-r7301. +config RTC_DRV_RPI + tristate "Raspberry Pi RTC" + depends on ARCH_BRCMSTB || COMPILE_TEST + default ARCH_BRCMSTB + help + If you say yes here you get support for the RTC found on + Raspberry Pi devices. + + This driver can also be built as a module. If so, the module + will be called rtc-rpi. + config RTC_DRV_STM32 tristate "STM32 RTC" select REGMAP_MMIO diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile index 0347645b021f..46f1a0fc2416 100644 --- a/drivers/rtc/Makefile +++ b/drivers/rtc/Makefile @@ -144,6 +144,7 @@ obj-$(CONFIG_RTC_DRV_PS3) += rtc-ps3.o obj-$(CONFIG_RTC_DRV_PXA) += rtc-pxa.o obj-$(CONFIG_RTC_DRV_R7301) += rtc-r7301.o obj-$(CONFIG_RTC_DRV_R9701) += rtc-r9701.o +obj-$(CONFIG_RTC_DRV_RPI) += rtc-raspberrypi.o obj-$(CONFIG_RTC_DRV_RC5T583) += rtc-rc5t583.o obj-$(CONFIG_RTC_DRV_RC5T619) += rtc-rc5t619.o obj-$(CONFIG_RTC_DRV_RK808) += rtc-rk808.o diff --git a/drivers/rtc/rtc-raspberrypi.c b/drivers/rtc/rtc-raspberrypi.c new file mode 100644 index 000000000000..af775ae55a87 --- /dev/null +++ b/drivers/rtc/rtc-raspberrypi.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 +#include +#include +#include +#include + +struct rpi_rtc_data { + struct rtc_device *rtc; + struct rpi_firmware *fw; + u32 bbat_vchg_millivolts; +}; + +#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_millivolts * 1000U}; + 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 %umV: %d\n", + vrtc->bbat_vchg_millivolts, err); + else if (vrtc->bbat_vchg_millivolts) + dev_info(dev, "trickle charging enabled at %umV\n", + vrtc->bbat_vchg_millivolts); + + 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 rpi_firmware *firmware; + int ret; + + // Check if our model is a Raspberry Pi 5, as the RTC is only present on that model. + const char *model = of_get_property(of_root, "model", NULL); + if (!model || strncmp(model, "Raspberry Pi 5", 14) != 0) { + dev_err(dev, "RTC is only available on Raspberry Pi 5\n"); + return -ENODEV; + } + + // Get the firmware device from the parent device + firmware = devm_rpi_firmware_get(dev, dev->parent->of_node); + + if (!firmware) + return -EPROBE_DEFER; + + vrtc = devm_kzalloc(dev, sizeof(*vrtc), GFP_KERNEL); + if (!vrtc) + return -ENOMEM; + + vrtc->fw = firmware; + + devm_device_init_wakeup(dev); + + platform_set_drvdata(pdev, vrtc); + + vrtc->rtc = devm_rtc_allocate_device(dev); + if (IS_ERR(vrtc->rtc)) + return PTR_ERR(vrtc->rtc); + + vrtc->rtc->range_max = U32_MAX; /* 2106-02-07 */ + + 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); + + vrtc->bbat_vchg_millivolts = 0; + of_property_read_u32(dev->parent->of_node, "trickle-charge-millivolt", + &vrtc->bbat_vchg_millivolts); + + 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,firmware-rtc"}, + {}, +}; +MODULE_DEVICE_TABLE(of, rpi_rtc_dt_match); + +static struct platform_driver rpi_rtc_driver = { + .probe = rpi_rtc_probe, + .driver = { + .name = "raspberrypi-rtc", + .of_match_table = rpi_rtc_dt_match, + }, +}; + +module_platform_driver(rpi_rtc_driver); + +MODULE_DESCRIPTION("Raspberry Pi RTC driver"); +MODULE_LICENSE("GPL"); -- 2.55.0