diff options
Diffstat (limited to 'drivers/hwmon/pmbus/ina233.c')
| -rw-r--r-- | drivers/hwmon/pmbus/ina233.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/drivers/hwmon/pmbus/ina233.c b/drivers/hwmon/pmbus/ina233.c new file mode 100644 index 000000000000..dde1e1678394 --- /dev/null +++ b/drivers/hwmon/pmbus/ina233.c @@ -0,0 +1,191 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Hardware monitoring driver for ina233 + * + * Copyright (c) 2025 Leo Yang + */ + +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include "pmbus.h" + +#define MFR_READ_VSHUNT 0xd1 +#define MFR_CALIBRATION 0xd4 + +#define INA233_MAX_CURRENT_DEFAULT 32768000 /* uA */ +#define INA233_RSHUNT_DEFAULT 2000 /* uOhm */ + +#define MAX_M_VAL 32767 + +static void calculate_coef(int *m, int *R, u32 current_lsb, int power_coef) +{ + u64 scaled_m; + int scale_factor = 0; + int scale_coef = 1; + + /* + * 1000000 from Current_LSB A->uA . + * scale_coef is for scaling up to minimize rounding errors, + * If there is no decimal information, no need to scale. + */ + if (1000000 % current_lsb) { + /* Scaling to keep integer precision */ + scale_factor = -3; + scale_coef = 1000; + } + + /* + * Unit Conversion (Current_LSB A->uA) and use scaling(scale_factor) + * to keep integer precision. + * Formulae referenced from spec. + */ + scaled_m = div64_u64(1000000 * scale_coef, (u64)current_lsb * power_coef); + + /* Maximize while keeping it bounded.*/ + while (scaled_m > MAX_M_VAL) { + scaled_m = div_u64(scaled_m, 10); + scale_factor++; + } + /* Scale up only if fractional part exists. */ + while (scaled_m * 10 < MAX_M_VAL && scale_coef != 1) { + scaled_m *= 10; + scale_factor--; + } + + *m = scaled_m; + *R = scale_factor; +} + +static int ina233_read_word_data(struct i2c_client *client, int page, + int phase, int reg) +{ + int ret; + + switch (reg) { + case PMBUS_VIRT_READ_VMON: + ret = pmbus_read_word_data(client, 0, 0xff, MFR_READ_VSHUNT); + + /* Adjust returned value to match VIN coefficients */ + /* VIN: 1.25 mV VSHUNT: 2.5 uV LSB */ + ret = DIV_ROUND_CLOSEST(ret * 25, 12500); + break; + default: + ret = -ENODATA; + break; + } + return ret; +} + +static int ina233_probe(struct i2c_client *client) +{ + struct device *dev = &client->dev; + int ret, m, R; + u32 rshunt; + u32 max_current; + u32 current_lsb; + u16 calibration; + struct pmbus_driver_info *info; + + info = devm_kzalloc(dev, sizeof(struct pmbus_driver_info), + GFP_KERNEL); + if (!info) + return -ENOMEM; + + info->pages = 1; + info->format[PSC_VOLTAGE_IN] = direct; + info->format[PSC_VOLTAGE_OUT] = direct; + info->format[PSC_CURRENT_OUT] = direct; + info->format[PSC_POWER] = direct; + info->func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_STATUS_INPUT + | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT + | PMBUS_HAVE_POUT + | PMBUS_HAVE_VMON | PMBUS_HAVE_STATUS_VMON; + info->m[PSC_VOLTAGE_IN] = 8; + info->R[PSC_VOLTAGE_IN] = 2; + info->m[PSC_VOLTAGE_OUT] = 8; + info->R[PSC_VOLTAGE_OUT] = 2; + info->read_word_data = ina233_read_word_data; + + /* If INA233 skips current/power, shunt-resistor and current-lsb aren't needed. */ + /* read rshunt value (uOhm) */ + ret = device_property_read_u32(dev, "shunt-resistor", &rshunt); + if (ret) { + if (ret != -EINVAL) + return dev_err_probe(dev, ret, "Shunt resistor property read fail.\n"); + rshunt = INA233_RSHUNT_DEFAULT; + } + if (!rshunt) + return dev_err_probe(dev, -EINVAL, + "Shunt resistor cannot be zero.\n"); + + /* read Maximum expected current value (uA) */ + ret = device_property_read_u32(dev, "ti,maximum-expected-current-microamp", &max_current); + if (ret) { + if (ret != -EINVAL) + return dev_err_probe(dev, ret, + "Maximum expected current property read fail.\n"); + max_current = INA233_MAX_CURRENT_DEFAULT; + } + if (max_current < 32768) + return dev_err_probe(dev, -EINVAL, + "Maximum expected current cannot less then 32768.\n"); + + /* Calculate Current_LSB according to the spec formula */ + current_lsb = max_current / 32768; + + /* calculate current coefficient */ + calculate_coef(&m, &R, current_lsb, 1); + info->m[PSC_CURRENT_OUT] = m; + info->R[PSC_CURRENT_OUT] = R; + + /* calculate power coefficient */ + calculate_coef(&m, &R, current_lsb, 25); + info->m[PSC_POWER] = m; + info->R[PSC_POWER] = R; + + /* write MFR_CALIBRATION register, Apply formula from spec with unit scaling. */ + calibration = div64_u64(5120000000ULL, (u64)rshunt * current_lsb); + if (calibration > 0x7FFF) + return dev_err_probe(dev, -EINVAL, + "Product of Current_LSB %u and shunt resistor %u too small, MFR_CALIBRATION reg exceeds 0x7FFF.\n", + current_lsb, rshunt); + ret = i2c_smbus_write_word_data(client, MFR_CALIBRATION, calibration); + if (ret < 0) + return dev_err_probe(dev, ret, "Unable to write calibration.\n"); + + dev_dbg(dev, "power monitor %s (Rshunt = %u uOhm, Current_LSB = %u uA/bit)\n", + client->name, rshunt, current_lsb); + + return pmbus_do_probe(client, info); +} + +static const struct i2c_device_id ina233_id[] = { + {"ina233", 0}, + {} +}; +MODULE_DEVICE_TABLE(i2c, ina233_id); + +static const struct of_device_id __maybe_unused ina233_of_match[] = { + { .compatible = "ti,ina233" }, + {} +}; +MODULE_DEVICE_TABLE(of, ina233_of_match); + +static struct i2c_driver ina233_driver = { + .driver = { + .name = "ina233", + .of_match_table = of_match_ptr(ina233_of_match), + }, + .probe = ina233_probe, + .id_table = ina233_id, +}; + +module_i2c_driver(ina233_driver); + +MODULE_AUTHOR("Leo Yang <leo.yang.sy0@gmail.com>"); +MODULE_DESCRIPTION("PMBus driver for INA233 and compatible chips"); +MODULE_LICENSE("GPL"); +MODULE_IMPORT_NS("PMBUS"); |