--- /dev/null
+// 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");
projects / linux-block.git / commitdiff