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[212.71.14.70]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a18c198134sm431809745e9.15.2026.10.14.01.30.34 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Oct 2026 01:30:34 -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, pbrobinson@gmail.com Subject: [PATCH v11 3/3] rtc: Add Raspberry Pi 5 RTC driver Date: Wed, 14 Oct 2026 10:30:16 +0200 Message-ID: <20261014083016.332338-4-sander.speetjens@gmail.com> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261014083016.332338-1-sander.speetjens@gmail.com> References: <20261014083016.332338-1-sander.speetjens@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261014_093037_386072_0C6D584C X-CRM114-Status: GOOD ( 39.50 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Upstreaming the downstream Raspberry Pi 5 RTC driver. This driver supports the custom DA9091, which is accessed through the firmware mailbox. Based on code originally written by Jonathan Bell and Dom Cobley Reviewed-by: Stefan Wahren Signed-off-by: Sander Speetjens --- V10 -> V11: - Change enum order in include - Remove compatible - Rename vrtc to rtc - Change from MODULE ALIAS to id_table V9 -> V10: - Fix sign-off-by - Change enum to defines - Change comment in firmware V8 -> V9: - Fix whitespace in Kconfig - Move RTC regs to firmware header - Add a warn when getting the min or max charging values fails - Remove the unused return value of set charge voltage V7 -> V8: - Fix whitespacing errors - Use of_machine_is_compatible instead of strncmp V6 -> V7: - Move from u32 array to struct - Fix encapsulation as mentioned by sashiko-bot V5 -> V6: - Add MODULE_ALIAS, as mentioned by sashiko-bot - Encapsulate the mailbox data in le32_to_cpu or cpu_to_le32, as mentioned by sashiko-bot. For good practice V4 -> V5: No changes V3 -> V4: - Fix Kconfig depends that disallows having Raspberrypi firmware built as a module while the rtc driver is built in - Remove sysfs - Add limits from firmware properties and check in rpi_rtc_set_charge_voltage V2 -> V3: - Move platform check to firmware and abort before registering a platform device if on another platform - Add a dependency on the Raspberry Pi firmware to Kconfig - Check return value of devm_device_init_wakeup - Fix property name 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. drivers/firmware/raspberrypi.c | 25 ++ drivers/rtc/Kconfig | 12 + drivers/rtc/Makefile | 1 + drivers/rtc/rtc-raspberrypi.c | 275 +++++++++++++++++++++ include/soc/bcm2835/raspberrypi-firmware.h | 2 + 5 files changed, 315 insertions(+) create mode 100644 drivers/rtc/rtc-raspberrypi.c diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c index 0aa322e9a2e7..b22c59a429de 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 +232,27 @@ static void rpi_register_clk_driver(struct device *dev) -1, NULL, 0); } +static void rpi_register_rtc_driver(struct device *dev) +{ + struct platform_device *pdev; + struct device_node *firmware; + + /* + * Check if our model of Raspberry Pi board is from the 5th gen + * as the RTC is only present on that model. + */ + if (!of_machine_is_compatible("brcm,bcm2712")) + return; + + pdev = platform_device_register_data(dev, "raspberrypi-rtc", + -1, NULL, 0); + + if (IS_ERR(pdev)) + return; + + rpi_rtc = pdev; +} + unsigned int rpi_firmware_clk_get_max_rate(struct rpi_firmware *fw, unsigned int id) { struct rpi_firmware_clk_rate_request msg = @@ -305,6 +327,7 @@ 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 +350,8 @@ 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..6adaf425a76b 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -1999,6 +1999,18 @@ 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 RASPBERRYPI_FIRMWARE || (COMPILE_TEST && !RASPBERRYPI_FIRMWARE) + 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 5th gen devices. + + This driver can also be built as a module. If so, the module + will be called rtc-raspberrypi. + 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..6d5c8111f4db --- /dev/null +++ b/drivers/rtc/rtc-raspberrypi.c @@ -0,0 +1,275 @@ +// 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 +#include +#include +#include +#include + +#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_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 "); +MODULE_AUTHOR("Sander Speetjens "); +MODULE_DESCRIPTION("Raspberry Pi RTC driver"); +MODULE_LICENSE("Dual BSD/GPL"); diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h index 975bef529854..8c3d43977a03 100644 --- a/include/soc/bcm2835/raspberrypi-firmware.h +++ b/include/soc/bcm2835/raspberrypi-firmware.h @@ -75,6 +75,7 @@ enum rpi_firmware_property_tag { RPI_FIRMWARE_GET_THROTTLED = 0x00030046, RPI_FIRMWARE_GET_CLOCK_MEASURED = 0x00030047, RPI_FIRMWARE_NOTIFY_REBOOT = 0x00030048, + RPI_FIRMWARE_GET_RTC_REG = 0x00030087, RPI_FIRMWARE_SET_CLOCK_STATE = 0x00038001, RPI_FIRMWARE_SET_CLOCK_RATE = 0x00038002, RPI_FIRMWARE_SET_VOLTAGE = 0x00038003, @@ -92,6 +93,7 @@ enum rpi_firmware_property_tag { RPI_FIRMWARE_SET_POE_HAT_VAL = 0x00030050, RPI_FIRMWARE_NOTIFY_XHCI_RESET = 0x00030058, RPI_FIRMWARE_NOTIFY_DISPLAY_DONE = 0x00030066, + RPI_FIRMWARE_SET_RTC_REG = 0x00038087, /* Dispmanx TAGS */ RPI_FIRMWARE_FRAMEBUFFER_ALLOCATE = 0x00040001, -- 2.56.0