It is designed as a generic UCLASS_THERMAL driver for any JEDEC JC-42.4 family of on-DIMM temperature sensors (TSE2004av and compatible parts).
The driver reads the temperature register over DM I2C. The "jedec,jc-42.4-temp" compatible is Linux-aligned (see Documentation/devicetree/bindings/hwmon/jedec,jc-42.4-temp.yaml in the Linux tree). When CMD_TEMPERATURE is enabled, the sensor becomes available with the standard commands "temperature list" / "temperature get". Signed-off-by: Vincent Jardin <[email protected]> --- MAINTAINERS | 5 +++ drivers/thermal/Kconfig | 7 +++ drivers/thermal/Makefile | 1 + drivers/thermal/jc42.c | 93 ++++++++++++++++++++++++++++++++++++++++ 4 files changed, 106 insertions(+) create mode 100644 drivers/thermal/jc42.c diff --git a/MAINTAINERS b/MAINTAINERS index 056902f6ef2..a7c86e3e29d 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1297,6 +1297,11 @@ T: git https://source.denx.de/u-boot/u-boot.git F: cmd/i3c.c F: drivers/i3c/ +JEDEC JC-42.4 / TSE2004av TEMPERATURE SENSOR +M: Vincent Jardin <[email protected]> +S: Maintained +F: drivers/thermal/jc42.c + KWBIMAGE / KWBOOT TOOLS M: Pali Rohár <[email protected]> M: Marek Behún <[email protected]> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig index 91c39aa4dee..04cf3bfa420 100644 --- a/drivers/thermal/Kconfig +++ b/drivers/thermal/Kconfig @@ -55,4 +55,11 @@ config TI_LM74_THERMAL Enable thermal support for the Texas Instruments LM74 chip. The driver supports reading CPU temperature. +config DM_THERMAL_JC42 + bool "JEDEC JC-42.4/TSE2004av SPD temperature sensor" + depends on DM_I2C + help + Enable support for the JEDEC JC-42.4 temperature sensor found + on the SPD bus of DDR3 and DDR4 DIMMs (TSE2004av and compatible). + endif # if DM_THERMAL diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile index b6f06c00ed9..c9fa7561b45 100644 --- a/drivers/thermal/Makefile +++ b/drivers/thermal/Makefile @@ -11,3 +11,4 @@ obj-$(CONFIG_RCAR_GEN3_THERMAL) += rcar_gen3_thermal.o obj-$(CONFIG_SANDBOX) += thermal_sandbox.o obj-$(CONFIG_TI_DRA7_THERMAL) += ti-bandgap.o obj-$(CONFIG_TI_LM74_THERMAL) += ti-lm74.o +obj-$(CONFIG_DM_THERMAL_JC42) += jc42.o diff --git a/drivers/thermal/jc42.c b/drivers/thermal/jc42.c new file mode 100644 index 00000000000..6945260e8b0 --- /dev/null +++ b/drivers/thermal/jc42.c @@ -0,0 +1,93 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright 2026 Free Mobile - Vincent Jardin + * + * JEDEC JC-42.4 / TSE2004av Temperature Sensor driver. + * + * Generic I2C temperature sensor of the Serial Presence Detect (SPD) + * bus of DDR3 and DDR4 SO-DIMMs / UDIMMs / RDIMMs per the JEDEC + * JC-42.4 standard. The TSE2004av variant adds an integrated SPD + * EEPROM, but the thermal register interface is the same and is + * what this driver exposes. + * + * Register layout (subset): + * 0x05 Ambient temperature, 16-bit big-endian: + * bit 15 : T_CRIT alarm flag (read-only) + * bit 14 : T_HIGH alarm flag (read-only) + * bit 13 : T_LOW alarm flag (read-only) + * bit 12 : sign (two's-complement within bits[12:0]) + * bits[11:0]: magnitude * 16 (LSB = 0.0625 degC = 62.5 mC) + * 0x06 Manufacturer ID (16-bit BE, JEP-106 vendor code) + * 0x07 Device ID + Revision (upper byte = ID, lower = revision) + * ... + */ + +#include <dm.h> +#include <i2c.h> +#include <thermal.h> +#include <linux/bitops.h> + +#define JC42_REG_TEMP 0x05 + +#define JC42_TEMP_SIGN BIT(12) +#define JC42_TEMP_MAGNITUDE GENMASK(11, 0) + +static int jc42_get_temp(struct udevice *dev, int *temp) +{ + u8 buf[2]; + int ret; + int mag; + + ret = dm_i2c_read(dev, JC42_REG_TEMP, buf, sizeof(buf)); + if (ret) + return ret; + + mag = ((buf[0] << 8) | buf[1]) & (JC42_TEMP_SIGN | JC42_TEMP_MAGNITUDE); + if (mag & JC42_TEMP_SIGN) + mag -= (JC42_TEMP_SIGN << 1); + + /* + * mag is in units of 1/16 degC. Multiply first to keep one + * extra bit of precision before the divide. Worst-case range + * for a 13-bit signed value is +/-4096, so the product fits + * comfortably in an int (~4.1M mC). + */ + *temp = mag * 1000 / 16; + + return 0; +} + +static const struct dm_thermal_ops jc42_ops = { + .get_temp = jc42_get_temp, +}; + +/* + * Optional DT label property override: it replace the default DM + * device name (the ofnode name, eg "temp@18") so + * temperature list or temperature get commands + * show a human-meaningful identifier such as "ddr-top" or + * "ddr-bottom". + * It mirrors the Linux hwmon binding which uses label for the + * per-sensor display name. + */ +static int jc42_bind(struct udevice *dev) +{ + const char *label = dev_read_string(dev, "label"); + + if (label && *label) + return device_set_name(dev, label); + return 0; +} + +static const struct udevice_id jc42_match[] = { + { .compatible = "jedec,jc-42.4-temp" }, + { } +}; + +U_BOOT_DRIVER(jc42_thermal) = { + .name = "jc42_thermal", + .id = UCLASS_THERMAL, + .of_match = jc42_match, + .bind = jc42_bind, + .ops = &jc42_ops, +}; -- 2.43.0 base-commit: bfe90a308a94caa9d855440683521ff04122ae2a branch: for-upstream/thermal-jc42
