// SPDX-License-Identifier: GPL-2.0-only /* * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller * * Copyright (C) 2008 Ira W. Snyder * * This driver is based on the ds1621 and ina209 drivers. * * Datasheet: * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517 */ #include #include #include #include #include #include #include #include #include #include #include /* Here are names of the chip's registers (a.k.a. commands) */ enum ltc4245_cmd { LTC4245_STATUS = 0x00, /* readonly */ LTC4245_ALERT = 0x01, LTC4245_CONTROL = 0x02, LTC4245_ON = 0x03, LTC4245_FAULT1 = 0x04, LTC4245_FAULT2 = 0x05, LTC4245_GPIO = 0x06, LTC4245_ADCADR = 0x07, LTC4245_12VIN = 0x10, LTC4245_12VSENSE = 0x11, LTC4245_12VOUT = 0x12, LTC4245_5VIN = 0x13, LTC4245_5VSENSE = 0x14, LTC4245_5VOUT = 0x15, LTC4245_3VIN = 0x16, LTC4245_3VSENSE = 0x17, LTC4245_3VOUT = 0x18, LTC4245_VEEIN = 0x19, LTC4245_VEESENSE = 0x1a, LTC4245_VEEOUT = 0x1b, LTC4245_GPIOADC = 0x1c, }; struct ltc4245_data { struct i2c_client *client; struct mutex update_lock; bool valid; unsigned long last_updated; /* in jiffies */ /* Control registers */ u8 cregs[0x08]; /* Voltage registers */ u8 vregs[0x0d]; /* GPIO ADC registers */ bool use_extra_gpios; int gpios[3]; }; /* * Update the readings from the GPIO pins. If the driver has been configured to * sample all GPIO's as analog voltages, a round-robin sampling method is used. * Otherwise, only the configured GPIO pin is sampled. * * LOCKING: must hold data->update_lock */ static void ltc4245_update_gpios(struct device *dev) { struct ltc4245_data *data = dev_get_drvdata(dev); struct i2c_client *client = data->client; u8 gpio_curr, gpio_next, gpio_reg; int i; /* no extra gpio support, we're basically done */ if (!data->use_extra_gpios) { data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10]; return; } /* * If the last reading was too long ago, then we mark all old GPIO * readings as stale by setting them to -EAGAIN */ if (time_after(jiffies, data->last_updated + 5 * HZ)) { for (i = 0; i < ARRAY_SIZE(data->gpios); i++) data->gpios[i] = -EAGAIN; } /* * Get the current GPIO pin * * The datasheet calls these GPIO[1-3], but we'll calculate the zero * based array index instead, and call them GPIO[0-2]. This is much * easier to think about. */ gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6; if (gpio_curr > 0) gpio_curr -= 1; /* Read the GPIO voltage from the GPIOADC register */ data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10]; /* Find the next GPIO pin to read */ gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios); /* * Calculate the correct setting for the GPIO register so it will * sample the next GPIO pin */ gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6); /* Update the GPIO register */ i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg); /* Update saved data */ data->cregs[LTC4245_GPIO] = gpio_reg; } static struct ltc4245_data *ltc4245_update_device(struct device *dev) { struct ltc4245_data *data = dev_get_drvdata(dev); struct i2c_client *client = data->client; s32 val; int i; mutex_lock(&data->update_lock); if (time_after(jiffies, data->last_updated + HZ) || !data->valid) { /* Read control registers -- 0x00 to 0x07 */ for (i = 0; i < ARRAY_SIZE(data->cregs); i++) { val = i2c_smbus_read_byte_data(client, i); if (unlikely(val < 0)) data->cregs[i] = 0; else data->cregs[i] = val; } /* Read voltage registers -- 0x10 to 0x1c */ for (i = 0; i < ARRAY_SIZE(data->vregs); i++) { val = i2c_smbus_read_byte_data(client, i+0x10); if (unlikely(val < 0)) data->vregs[i] = 0; else data->vregs[i] = val; } /* Update GPIO readings */ ltc4245_update_gpios(dev); data->last_updated = jiffies; data->valid = true; } mutex_unlock(&data->update_lock); return data; } /* Return the voltage from the given register in millivolts */ static int ltc4245_get_voltage(struct device *dev, u8 reg) { struct ltc4245_data *data = ltc4245_update_device(dev); const u8 regval = data->vregs[reg - 0x10]; u32 voltage = 0; switch (reg) { case LTC4245_12VIN: case LTC4245_12VOUT: voltage = regval * 55; break; case LTC4245_5VIN: case LTC4245_5VOUT: voltage = regval * 22; break; case LTC4245_3VIN: case LTC4245_3VOUT: voltage = regval * 15; break; case LTC4245_VEEIN: case LTC4245_VEEOUT: voltage = regval * -55; break; case LTC4245_GPIOADC: voltage = regval * 10; break; default: /* If we get here, the developer messed up */ WARN_ON_ONCE(1); break; } return voltage; } /* Return the current in the given sense register in milliAmperes */ static unsigned int ltc4245_get_current(struct device *dev, u8 reg) { struct ltc4245_data *data = ltc4245_update_device(dev); const u8 regval = data->vregs[reg - 0x10]; unsigned int voltage; unsigned int curr; /* * The strange looking conversions that follow are fixed-point * math, since we cannot do floating point in the kernel. * * Step 1: convert sense register to microVolts * Step 2: convert voltage to milliAmperes * * If you play around with the V=IR equation, you come up with * the following: X uV / Y mOhm == Z mA * * With the resistors that are fractions of a milliOhm, we multiply * the voltage and resistance by 10, to shift the decimal point. * Now we can use the normal division operator again. */ switch (reg) { case LTC4245_12VSENSE: voltage = regval * 250; /* voltage in uV */ curr = voltage / 50; /* sense resistor 50 mOhm */ break; case LTC4245_5VSENSE: voltage = regval * 125; /* voltage in uV */ curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */ break; case LTC4245_3VSENSE: voltage = regval * 125; /* voltage in uV */ curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */ break; case LTC4245_VEESENSE: voltage = regval * 250; /* voltage in uV */ curr = voltage / 100; /* sense resistor 100 mOhm */ break; default: /* If we get here, the developer messed up */ WARN_ON_ONCE(1); curr = 0; break; } return curr; } /* Map from voltage channel index to voltage register */ static const s8 ltc4245_in_regs[] = { LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN, LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT, }; /* Map from current channel index to current register */ static const s8 ltc4245_curr_regs[] = { LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE, }; static int ltc4245_read_curr(struct device *dev, u32 attr, int channel, long *val) { struct ltc4245_data *data = ltc4245_update_device(dev); switch (attr) { case hwmon_curr_input: *val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]); return 0; case hwmon_curr_max_alarm: *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4)); return 0; default: return -EOPNOTSUPP; } } static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val) { struct ltc4245_data *data = ltc4245_update_device(dev); switch (attr) { case hwmon_in_input: if (channel < 8) { *val = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]); } else { int regval = data->gpios[channel - 8]; if (regval < 0) return regval; *val = regval * 10; } return 0; case hwmon_in_min_alarm: if (channel < 4) *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel)); else *val = !!(data->cregs[LTC4245_FAULT2] & BIT(channel - 4)); return 0; default: return -EOPNOTSUPP; } } static int ltc4245_read_power(struct device *dev, u32 attr, int channel, long *val) { unsigned long curr; long voltage; switch (attr) { case hwmon_power_input: (void)ltc4245_update_device(dev); curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]); voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]); *val = abs(curr * voltage); return 0; default: return -EOPNOTSUPP; } } static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type, u32 attr, int channel, long *val) { switch (type) { case hwmon_curr: return ltc4245_read_curr(dev, attr, channel, val); case hwmon_power: return ltc4245_read_power(dev, attr, channel, val); case hwmon_in: return ltc4245_read_in(dev, attr, channel - 1, val); default: return -EOPNOTSUPP; } } static umode_t ltc4245_is_visible(const void *_data, enum hwmon_sensor_types type, u32 attr, int channel) { const struct ltc4245_data *data = _data; switch (type) { case hwmon_in: if (channel == 0) return 0; switch (attr) { case hwmon_in_input: if (channel > 9 && !data->use_extra_gpios) return 0; return 0444; case hwmon_in_min_alarm: if (channel > 8) return 0; return 0444; default: return 0; } case hwmon_curr: switch (attr) { case hwmon_curr_input: case hwmon_curr_max_alarm: return 0444; default: return 0; } case hwmon_power: switch (attr) { case hwmon_power_input: return 0444; default: return 0; } default: return 0; } } static const struct hwmon_channel_info *ltc4245_info[] = { HWMON_CHANNEL_INFO(in, HWMON_I_INPUT, HWMON_I_INPUT | HWMON_I_MIN_ALARM, HWMON_I_INPUT | HWMON_I_MIN_ALARM, HWMON_I_INPUT | HWMON_I_MIN_ALARM, HWMON_I_INPUT | HWMON_I_MIN_ALARM, HWMON_I_INPUT | HWMON_I_MIN_ALARM, HWMON_I_INPUT | HWMON_I_MIN_ALARM, HWMON_I_INPUT | HWMON_I_MIN_ALARM, HWMON_I_INPUT | HWMON_I_MIN_ALARM, HWMON_I_INPUT, HWMON_I_INPUT, HWMON_I_INPUT), HWMON_CHANNEL_INFO(curr, HWMON_C_INPUT | HWMON_C_MAX_ALARM, HWMON_C_INPUT | HWMON_C_MAX_ALARM, HWMON_C_INPUT | HWMON_C_MAX_ALARM, HWMON_C_INPUT | HWMON_C_MAX_ALARM), HWMON_CHANNEL_INFO(power, HWMON_P_INPUT, HWMON_P_INPUT, HWMON_P_INPUT, HWMON_P_INPUT), NULL }; static const struct hwmon_ops ltc4245_hwmon_ops = { .is_visible = ltc4245_is_visible, .read = ltc4245_read, }; static const struct hwmon_chip_info ltc4245_chip_info = { .ops = <c4245_hwmon_ops, .info = ltc4245_info, }; static bool ltc4245_use_extra_gpios(struct i2c_client *client) { struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev); struct device_node *np = client->dev.of_node; /* prefer platform data */ if (pdata) return pdata->use_extra_gpios; /* fallback on OF */ if (of_find_property(np, "ltc4245,use-extra-gpios", NULL)) return true; return false; } static int ltc4245_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct i2c_adapter *adapter = client->adapter; struct ltc4245_data *data; struct device *hwmon_dev; if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) return -ENODEV; data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); if (!data) return -ENOMEM; data->client = client; mutex_init(&data->update_lock); data->use_extra_gpios = ltc4245_use_extra_gpios(client); /* Initialize the LTC4245 chip */ i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00); i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00); hwmon_dev = devm_hwmon_device_register_with_info(&client->dev, client->name, data, <c4245_chip_info, NULL); return PTR_ERR_OR_ZERO(hwmon_dev); } static const struct i2c_device_id ltc4245_id[] = { { "ltc4245", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, ltc4245_id); /* This is the driver that will be inserted */ static struct i2c_driver ltc4245_driver = { .driver = { .name = "ltc4245", }, .probe = ltc4245_probe, .id_table = ltc4245_id, }; module_i2c_driver(ltc4245_driver); MODULE_AUTHOR("Ira W. Snyder "); MODULE_DESCRIPTION("LTC4245 driver"); MODULE_LICENSE("GPL");