Add ADI LTC7871 buck-boost controller driver support.
Signed-off-by: Celine Joy A. Capua <celinejoy.capua@xxxxxxxxxx>
---
drivers/regulator/Kconfig | 11 +
drivers/regulator/Makefile | 1 +
drivers/regulator/ltc7871-regulator.c | 405 ++++++++++++++++++++++++++++++++++
3 files changed, 417 insertions(+)
diff --git a/drivers/regulator/Kconfig b/drivers/regulator/Kconfig
index 39297f7d8177193e51c99bc2b360c6d9936e62fe..500e8d7a198c597a479f80866a9733ebf945e15f 100644
--- a/drivers/regulator/Kconfig
+++ b/drivers/regulator/Kconfig
@@ -566,6 +566,17 @@ config REGULATOR_LTC3676
This enables support for the LTC3676
8-output regulators controlled via I2C.
+config REGULATOR_LTC7871
+ tristate "LTC7871 six-phase buck-boost voltage regulator driver with SPI"
+ depends on SPI && OF
+ help
+ This driver controls an Analog Devices LTC7871 high performance
+ bidirectional buck or boost switching regulator controller
+ that operates in either buck or boost mode on demand.
+
+ Say M here if you want to include support for the regulator as a
+ module.
+
config REGULATOR_MAX14577
tristate "Maxim 14577/77836 regulator"
depends on MFD_MAX14577
diff --git a/drivers/regulator/Makefile b/drivers/regulator/Makefile
index 3d5a803dce8a0556ba9557fa069c6e37593b3c69..47e26fcf39db39da542a7bc4df05b214c4b7cc0f 100644
--- a/drivers/regulator/Makefile
+++ b/drivers/regulator/Makefile
@@ -69,6 +69,7 @@ obj-$(CONFIG_REGULATOR_LP8788) += lp8788-ldo.o
obj-$(CONFIG_REGULATOR_LP8755) += lp8755.o
obj-$(CONFIG_REGULATOR_LTC3589) += ltc3589.o
obj-$(CONFIG_REGULATOR_LTC3676) += ltc3676.o
+obj-$(CONFIG_REGULATOR_LTC7871) += ltc7871-regulator.o
obj-$(CONFIG_REGULATOR_MAX14577) += max14577-regulator.o
obj-$(CONFIG_REGULATOR_MAX1586) += max1586.o
obj-$(CONFIG_REGULATOR_MAX5970) += max5970-regulator.o
diff --git a/drivers/regulator/ltc7871-regulator.c b/drivers/regulator/ltc7871-regulator.c
new file mode 100644
index 0000000000000000000000000000000000000000..eeea952f9362e48e0f6b85309a0c273f77776cb0
--- /dev/null
+++ b/drivers/regulator/ltc7871-regulator.c
@@ -0,0 +1,405 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Analog Devices LTC7871 Voltage Regulator Driver
+ *
+ * Copyright 2025 Analog Devices Inc.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/crc8.h>
+#include <linux/math.h>
+#include <linux/module.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/of_regulator.h>
+#include <linux/spi/spi.h>
+
+#define LTC7871_REG_FAULT 0x01
+#define LTC7871_REG_CONFIG2 0x06
+#define LTC7871_REG_CHIP_CTRL 0x07
+#define LTC7871_REG_IDAC_VLOW 0x08
+#define LTC7871_REG_IDAC_VHIGH 0x09
+#define LTC7871_REG_SETCUR 0x0A
+#define LTC7871_REG_SSFM 0x0B
+
+#define LTC7871_FAULT_OVER_TEMP BIT(0)
+#define LTC7871_FAULT_VHIGH_UV BIT(4)
+#define LTC7871_FAULT_VHIGH_OV BIT(5)
+#define LTC7871_FAULT_VLOW_OV BIT(6)
+
+#define LTC7871_MASK_CONFIG2_BUCK_BOOST BIT(0)
+
+#define LTC7871_MASK_CHIP_CTRL_WP BIT(0)
+
+#define LTC7871_MASK_SSFM_FREQ_SPREAD GENMASK(4, 3)
+#define LTC7871_MASK_SSFM_MOD_SIG_FREQ GENMASK(2, 0)
+
+#define LTC7871_CRC_INIT 0x41
+#define LTC7871_CRC8_POLY 0x7
+#define LTC7871_DATA_POS 1
+#define LTC7871_CRC_POS 2
+#define LTC7871_FRAME_SIZE 3
+
+#define LTC7871_IDAC_MAX 63
+#define LTC7871_IDAC_MIN -64
+
+DECLARE_CRC8_TABLE(ltc7871_crc8_table);
+
+struct ltc7871 {
+ struct spi_device *spi;
+ struct regulator_dev *rdev;
+ bool enable_chip_ctrl_wp;
+ bool regulator_mode;
+ u32 ra_ext;
+ u32 rb_ext;
+ u32 rc_ext;
+ u32 rd_ext;
+ u32 r1;
+ u32 r2;
+ u32 max_vol;
+ u32 min_vol;
+ s32 idac_setcur_uA;
+ const char *freq_spread_percentage;
+ u32 switching_freq_divider;
+};
+
+static const char * const ltc7871_freq_spread_percentage[] = {
+ "+-12%",
+ "+-15%",
+ "+-10%",
+ "+-8%",
+};
+
+static const unsigned int ltc7871_switching_freq_divider[] = {
+ 512,
+ 1024,
+ 2048,
+ 4096,
+ 256,
+ 128,
+ 64,
+};
+
+static int ltc7871_reg_read(struct spi_device *spi, u8 reg, int *val)
+{
+ int ret;
+ struct spi_transfer t;
+ u8 crc;
+ u8 rx_buf[LTC7871_FRAME_SIZE] = {0};
+ u8 tx_buf[LTC7871_FRAME_SIZE] = {0};
+
+ tx_buf[0] = reg << 1 | 1;
+
+ t.tx_buf = tx_buf;
+ t.rx_buf = rx_buf;
+ t.len = LTC7871_FRAME_SIZE;
+
+ crc = crc8(ltc7871_crc8_table, rx_buf, LTC7871_CRC_POS,
+ LTC7871_CRC_INIT);
+
+ ret = spi_sync_transfer(spi, &t, 1);
+ if (ret < 0)
+ return ret;
+
+ if (rx_buf[LTC7871_CRC_POS] != crc)
+ return -EIO;
+
+ return 0;
+}
+
+static int ltc7871_reg_write(struct spi_device *spi, u8 reg, int val)
+{
+ struct spi_transfer t;
+ u8 rx_buf[LTC7871_FRAME_SIZE] = {0};
+ u8 tx_buf[LTC7871_FRAME_SIZE] = {0};
+
+ tx_buf[0] = reg << 1;
+ tx_buf[1] = val;
+ tx_buf[2] = crc8(ltc7871_crc8_table, tx_buf, LTC7871_CRC_POS, LTC7871_CRC_INIT);
+
+ t.tx_buf = tx_buf;
+ t.rx_buf = rx_buf;
+ t.len = LTC7871_FRAME_SIZE;
+
+ return spi_sync_transfer(spi, &t, 1);
+}
+
+static int ltc7871_get_error_flags(struct regulator_dev *rdev,
+ unsigned int *flags)
+{
+ u32 val;
+ int ret;
+ struct ltc7871 *ltc7871 = rdev_get_drvdata(rdev);
+
+ ret = ltc7871_reg_read(ltc7871->spi, LTC7871_REG_FAULT, &val);
+ if (ret)
+ return ret;
+
+ *flags = 0;
+
+ if (FIELD_GET(LTC7871_FAULT_VHIGH_OV, val) ||
+ FIELD_GET(LTC7871_FAULT_VLOW_OV, val))
+ *flags |= REGULATOR_ERROR_OVER_VOLTAGE_WARN;
+
+ if (FIELD_GET(LTC7871_FAULT_VHIGH_UV, val))
+ *flags |= REGULATOR_ERROR_UNDER_VOLTAGE;
+
+ if (FIELD_GET(LTC7871_FAULT_OVER_TEMP, val))
+ *flags |= REGULATOR_ERROR_OVER_TEMP;
+
+ return 0;
+}
+
+static s64 _ltc7871_dac_to_uV(struct ltc7871 *ltc7871, u32 dac_val)
+{
+ s64 tmp;
+
+ tmp = 1200 * (1000 + (div_s64(ltc7871->r2 * 1000, ltc7871->r1)));
+ tmp = tmp - dac_val * ltc7871->r2;
+
+ return tmp;
+}
+
+static s64 _ltc7871_uV_to_dac(struct ltc7871 *ltc7871, s32 uV)
+{
+ s64 tmp;
+
+ tmp = 1200 * (1000 + (div_s64(ltc7871->r2 * 1000, ltc7871->r1))) - uV;
+ tmp = div_s64(tmp, ltc7871->r2);
+
+ return tmp;
+}
+
+static int ltc7871_set_voltage_sel(struct regulator_dev *rdev,
+ unsigned int sel)
+{
+ int reg;
+ int addr;
+ struct ltc7871 *ltc7871 = rdev_get_drvdata(rdev);
+
+ if (sel < ltc7871->min_vol || sel > ltc7871->max_vol)
+ return -EINVAL;
+
+ if (ltc7871->regulator_mode)
+ addr = LTC7871_REG_IDAC_VLOW;
+ else
+ addr = LTC7871_REG_IDAC_VHIGH;
+
+ reg = _ltc7871_uV_to_dac(ltc7871, sel);
+
+ return ltc7871_reg_write(ltc7871->spi, addr, reg);
+}
+
+static int ltc7871_get_voltage_sel(struct regulator_dev *rdev)
+{
+ int reg, ret;
+ int addr;
+ struct ltc7871 *ltc7871 = rdev_get_drvdata(rdev);
+
+ if (ltc7871->regulator_mode)
+ addr = LTC7871_REG_IDAC_VLOW;
+ else
+ addr = LTC7871_REG_IDAC_VHIGH;
+
+ ret = ltc7871_reg_read(ltc7871->spi, addr, ®);
+ if (ret < 0)
+ return ret;
+
+ return _ltc7871_dac_to_uV(ltc7871, reg);
+}
+
+static int ltc7871_get_prop_index(const u32 *table, size_t table_size, u32 value)
+{
+ int i;
+
+ for (i = 0; i < table_size; i++)
+ if (table[i] == value)
+ return i;
+
+ return -EINVAL;
+}
+
+static int ltc7871_parse_fw(struct ltc7871 *chip)
+{
+ int reg, ret;
+ int val1, val2;
+
+ /* Setting default values based on datasheet and DC2886A Schematic */
+ chip->idac_setcur_uA = 0;
+ chip->freq_spread_percentage = "+-12%";
+ chip->switching_freq_divider = 512;
+ chip->enable_chip_ctrl_wp = 0;
+ chip->ra_ext = 10000;
+ chip->rb_ext = 107000;
+ chip->rc_ext = 12700;
+ chip->rd_ext = 499000;
+
+ ret = device_property_read_u32(&chip->spi->dev, "adi,ra-external-ohms",
+ &chip->ra_ext);
+ if (!ret) {
+ if (!chip->ra_ext)
+ return -EINVAL;
+ }
+
+ ret = device_property_read_u32(&chip->spi->dev, "adi,rb-external-ohms",
+ &chip->rb_ext);
+ if (!ret) {
+ if (!chip->rb_ext)
+ return -EINVAL;
+ }
+
+ ret = device_property_read_u32(&chip->spi->dev, "adi,rc-external-ohms",
+ &chip->rc_ext);
+ if (!ret) {
+ if (!chip->rc_ext)
+ return -EINVAL;
+ }
+
+ ret = device_property_read_u32(&chip->spi->dev, "adi,rd-external-ohms",
+ &chip->rd_ext);
+ if (!ret) {
+ if (!chip->rd_ext)
+ return -EINVAL;
+ }
+
+ ret = ltc7871_reg_read(chip->spi, LTC7871_REG_CONFIG2, ®);
+ if (ret < 0)
+ return ret;
+
+ chip->regulator_mode = FIELD_GET(LTC7871_MASK_CONFIG2_BUCK_BOOST, reg);
+
+ if (chip->regulator_mode) {
+ chip->r1 = chip->ra_ext;
+ chip->r2 = chip->rb_ext;
+ } else {
+ chip->r1 = chip->rc_ext;
+ chip->r2 = chip->rd_ext;
+ }
+ chip->min_vol = _ltc7871_dac_to_uV(chip, LTC7871_IDAC_MAX);
+ chip->max_vol = _ltc7871_dac_to_uV(chip, LTC7871_IDAC_MIN);
+
+ ret = ltc7871_reg_read(chip->spi, LTC7871_REG_CHIP_CTRL, ®);
+ if (ret < 0)
+ return ret;
+
+ chip->enable_chip_ctrl_wp = device_property_read_bool(&chip->spi->dev,
+ "adi,enable-chip-ctrl-wp");
+ val1 = FIELD_PREP(LTC7871_MASK_CHIP_CTRL_WP, chip->enable_chip_ctrl_wp) | reg;
+ ret = ltc7871_reg_write(chip->spi, LTC7871_REG_CHIP_CTRL, val1);
+ if (ret)
+ return ret;
+
+ ret = device_property_read_u32(&chip->spi->dev, "adi,idac-setcur-microamp",
+ &chip->idac_setcur_uA);
+ if (!ret) {
+ if (chip->idac_setcur_uA < LTC7871_IDAC_MIN ||
+ chip->idac_setcur_uA > LTC7871_IDAC_MAX) {
+ return -EINVAL;
+ }
+
+ ret = ltc7871_reg_write(chip->spi, LTC7871_REG_SETCUR,
+ chip->idac_setcur_uA);
+ if (ret)
+ return ret;
+ }
+ ret = device_property_match_property_string(&chip->spi->dev,
+ "adi,freq-spread-percentage",
+ ltc7871_freq_spread_percentage,
+ ARRAY_SIZE(ltc7871_freq_spread_percentage));
+
+ if (ret >= 0)
+ val1 = FIELD_PREP(LTC7871_MASK_SSFM_FREQ_SPREAD, ret);
+ else
+ val1 = 0;
+
+ ret = device_property_read_u32(&chip->spi->dev,
+ "adi,switching-freq-divider",
+ &chip->switching_freq_divider);
+ if (!ret) {
+ ret = ltc7871_get_prop_index(ltc7871_switching_freq_divider,
+ ARRAY_SIZE(ltc7871_switching_freq_divider),
+ chip->switching_freq_divider);
+ if (ret < 0)
+ return ret;
+
+ val2 = FIELD_PREP(LTC7871_MASK_SSFM_MOD_SIG_FREQ, ret);
+ }
+
+ return ltc7871_reg_write(chip->spi, LTC7871_REG_SSFM, val1 | val2);
+}
+
+static const struct regulator_ops ltc7871_regulator_ops = {
+ .set_voltage_sel = ltc7871_set_voltage_sel,
+ .get_voltage_sel = ltc7871_get_voltage_sel,
+ .get_error_flags = ltc7871_get_error_flags,
+};
+
+static const struct regulator_desc ltc7871_regulator_desc = {
+ .ops = <c7871_regulator_ops,
+ .name = "ltc7871",
+ .type = REGULATOR_VOLTAGE,
+ .owner = THIS_MODULE,
+};
+
+static int ltc7871_probe(struct spi_device *spi)
+{
+ int ret;
+ struct regulator_init_data *init_data;
+ struct device *dev = &spi->dev;
+ struct regulator_config config = { };
+ struct ltc7871 *chip;
+
+ init_data = of_get_regulator_init_data(dev, spi->dev.of_node,
+ <c7871_regulator_desc);
+ if (!init_data)
+ return -EINVAL;
+
+ chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+ if (!chip)
+ return -ENOMEM;
+
+ crc8_populate_msb(ltc7871_crc8_table, LTC7871_CRC8_POLY);
+
+ chip->spi = spi;
+
+ ret = ltc7871_parse_fw(chip);
+ if (ret < 0)
+ return ret;
+
+ config.dev = dev;
+ config.init_data = init_data;
+ config.driver_data = chip;
+
+ chip->rdev = devm_regulator_register(dev, <c7871_regulator_desc,
+ &config);
+
+ return PTR_ERR_OR_ZERO(chip->rdev);
+}
+
+static const struct of_device_id ltc7871_of_match[] = {
+ { .compatible = "adi,ltc7871", },
+ { .compatible = "adi,ltc7872", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, ltc7871_of_match);
+
+static const struct spi_device_id ltc7871_id[] = {
+ {"ltc7871" },
+ {"ltc7872" },
+ { },
+};
+MODULE_DEVICE_TABLE(spi, ltc7871_id);
+
+static struct spi_driver ltc7871_driver = {
+ .driver = {
+ .name = "ltc7871",
+ .of_match_table = ltc7871_of_match,
+ },
+ .probe = ltc7871_probe,
+ .id_table = ltc7871_id,
+};
+module_spi_driver(ltc7871_driver);
+
+MODULE_DESCRIPTION("LTC7871 Voltage Regulator Driver");
+MODULE_AUTHOR("Celine Joy Capua <celinejoy.capua@xxxxxxxxxx>");
+MODULE_LICENSE("GPL");
--
2.34.1
