Add Linux support for the Linear Technology LTC4245 Multiple Supply Hot Swap controller I2C monitoring interface. Signed-off-by: Ira W. Snyder <iws at ovro.caltech.edu> --- I've incorporated the suggestions from my first posting of this driver. I decided to add current and power readings for the Vee (-12v) voltage, as well as the 12v, 5v, and 3v mentioned in the suggestions. This seemed reasonable to me. I'd appreciate any more suggestions you may have. :) Changes v1 -> v2: * fixed checkpatch warnings * removed raw register access, per suggestions * changed sysfs interface, per suggestions (current, power, alarms) Documentation/hwmon/ltc4245 | 69 +++++ drivers/hwmon/Kconfig | 11 + drivers/hwmon/Makefile | 1 + drivers/hwmon/ltc4245.c | 669 +++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 750 insertions(+), 0 deletions(-) create mode 100644 Documentation/hwmon/ltc4245 create mode 100644 drivers/hwmon/ltc4245.c diff --git a/Documentation/hwmon/ltc4245 b/Documentation/hwmon/ltc4245 new file mode 100644 index 0000000..dcb1973 --- /dev/null +++ b/Documentation/hwmon/ltc4245 @@ -0,0 +1,69 @@ +Kernel driver ltc4245 +===================== + +Supported chips: + * Linear Technology LTC4245 + Prefix: 'ltc4245' + Addresses scanned: 0x20-0x3f + Datasheet: + http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517 + +Author: Ira W. Snyder <iws at ovro.caltech.edu> + + +Description +----------- + +The LTC4245 controller allows a board to be safely inserted and removed +from a live backplane in multiple supply systems such as CompactPCI and +PCI Express. + + +Sysfs entries +------------- + +The LTC4245 has built-in limits for over and under current warnings. This +makes it very likely that the reference circuit will be used. + +This driver uses the values in the datasheet to change the register values +into the values specified in the sysfs-interface document. The current readings +rely on the sense resistors listed in Table 2: "Sense Resistor Values". + +in1_input 12v input voltage (mV) +in2_input 5v input voltage (mV) +in3_input 3v input voltage (mV) +in4_input Vee (-12v) input voltage (mV) + +in1_min_alarm 12v undervoltage alarm +in2_min_alarm 5v undervoltage alarm +in3_min_alarm 3v undervoltage alarm +in4_min_alarm Vee (-12v) undervoltage alarm + +curr1_input 12v current (mA) +curr2_input 5v current (mA) +curr3_input 3v current (mA) +curr4_input Vee (-12v) current (mA) + +curr1_max_alarm 12v overcurrent alarm +curr2_max_alarm 5v overcurrent alarm +curr3_max_alarm 3v overcurrent alarm +curr4_max_alarm Vee (-12v) overcurrent alarm + +in5_input 12v output voltage (mV) +in6_input 5v output voltage (mV) +in7_input 3v output voltage (mV) +in8_input Vee (-12v) output voltage (mV) + +in9_input GPIO #1 voltage data +in10_input GPIO #2 voltage data +in11_input GPIO #3 voltage data + +power1_input 12v power usage (mW) +power2_input 5v power usage (mW) +power3_input 3v power usage (mW) +power4_input Vee (-12v) power usage (mW) + +power1_alarm 12v power bad alarm +power2_alarm 5v power bad alarm +power3_alarm 3v power bad alarm +power4_alarm Vee (-12v) power bad alarm diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig index d402e8d..91bec8a 100644 --- a/drivers/hwmon/Kconfig +++ b/drivers/hwmon/Kconfig @@ -836,6 +836,17 @@ config SENSORS_APPLESMC Say Y here if you have an applicable laptop and want to experience the awesome power of applesmc. +config SENSORS_LTC4245 + tristate "Linear Technology LTC4245" + depends on I2C && EXPERIMENTAL + default n + help + If you say yes here you get support for Linear Technology LTC4245 + Multiple Supply Hot Swap Controller I2C interface. + + This driver can also be built as a module. If so, the module will + be called ltc4245. + config HWMON_DEBUG_CHIP bool "Hardware Monitoring Chip debugging messages" default n diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index 950134a..0ed56ac 100644 --- a/drivers/hwmon/Makefile +++ b/drivers/hwmon/Makefile @@ -59,6 +59,7 @@ obj-$(CONFIG_SENSORS_LM87) += lm87.o obj-$(CONFIG_SENSORS_LM90) += lm90.o obj-$(CONFIG_SENSORS_LM92) += lm92.o obj-$(CONFIG_SENSORS_LM93) += lm93.o +obj-$(CONFIG_SENSORS_LTC4245) += ltc4245.o obj-$(CONFIG_SENSORS_MAX1619) += max1619.o obj-$(CONFIG_SENSORS_MAX6650) += max6650.o obj-$(CONFIG_SENSORS_PC87360) += pc87360.o diff --git a/drivers/hwmon/ltc4245.c b/drivers/hwmon/ltc4245.c new file mode 100644 index 0000000..5189917 --- /dev/null +++ b/drivers/hwmon/ltc4245.c @@ -0,0 +1,669 @@ +/* + * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller + * + * Copyright (C) 2008 Ira W. Snyder <iws at ovro.caltech.edu> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * 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 <linux/module.h> +#include <linux/init.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/i2c.h> +#include <linux/hwmon.h> +#include <linux/hwmon-sysfs.h> + +/* Addresses to probe */ +static unsigned short normal_i2c[] = { + 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, + 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, + 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, + 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, + I2C_CLIENT_END}; + +/* Insmod parameters */ +I2C_CLIENT_INSMOD_1(ltc4245); + +/* 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_GPIOADC1 = 0x1c, + LTC4245_GPIOADC2 = 0x1d, + LTC4245_GPIOADC3 = 0x1e, +}; + +struct ltc4245_data { + struct device *hwmon_dev; + + struct mutex update_lock; + bool valid; + unsigned long last_updated; /* in jiffies */ + + /* Control registers */ + u8 cregs[0x08]; + + /* Voltage registers */ + u8 vregs[0x0f]; +}; + +/* All registers are byte-sized (8 bit) */ +static s32 ltc4245_read_reg(struct i2c_client *client, u8 reg) +{ + return i2c_smbus_read_byte_data(client, reg); +} + +#if 0 +static s32 ltc4245_write_reg(struct i2c_client *client, u8 reg, u8 val) +{ + return i2c_smbus_write_byte_data(client, reg, val); +} +#endif + +static struct ltc4245_data *ltc4245_update_device(struct device *dev) +{ + struct i2c_client *client = to_i2c_client(dev); + struct ltc4245_data *data = i2c_get_clientdata(client); + int i; + + mutex_lock(&data->update_lock); + + if (time_after(jiffies, data->last_updated + HZ) || !data->valid) { + + dev_dbg(&client->dev, "Starting ltc4245 update\n"); + + /* Read control registers -- 0x00 to 0x07 */ + for (i = 0; i < ARRAY_SIZE(data->cregs); i++) + data->cregs[i] = ltc4245_read_reg(client, i); + + /* Read voltage registers -- 0x10 to 0x1f */ + for (i = 0; i < ARRAY_SIZE(data->vregs); i++) + data->vregs[i] = ltc4245_read_reg(client, i+0x10); + + data->last_updated = jiffies; + data->valid = 1; + } + + mutex_unlock(&data->update_lock); + + return data; +} + +/* Return the voltage from the given register in millivolts */ +static u32 ltc4245_get_voltage(struct device *dev, u8 reg) +{ + struct ltc4245_data *data = ltc4245_update_device(dev); + const s32 val = data->vregs[reg - 0x10]; + const u8 regval = val; + u32 mv = 0; + + if (unlikely(val < 0)) + return 0; + + switch (reg) { + case LTC4245_12VIN: + case LTC4245_12VOUT: + mv = regval * 55; + break; + case LTC4245_12VSENSE: + mv = regval * 250 / 1000; + break; + case LTC4245_5VIN: + case LTC4245_5VOUT: + mv = regval * 22; + break; + case LTC4245_5VSENSE: + mv = regval * 125 / 1000; + break; + case LTC4245_3VIN: + case LTC4245_3VOUT: + mv = regval * 15; + break; + case LTC4245_3VSENSE: + mv = regval * 125 / 1000; + break; + case LTC4245_VEEIN: + case LTC4245_VEEOUT: + mv = regval * 55; + break; + case LTC4245_VEESENSE: + mv = regval * 250 / 1000; + break; + case LTC4245_GPIOADC1: + case LTC4245_GPIOADC2: + case LTC4245_GPIOADC3: + mv = regval * 10; + break; + default: + WARN_ON_ONCE(1); + break; + } + + return mv; +} + +/* Return the current in the given sense register in milliAmperes */ +static u32 ltc4245_get_current(struct device *dev, u8 reg) +{ + const u32 voltage = ltc4245_get_voltage(dev, reg); + + switch (reg) { + case LTC4245_12VSENSE: + return voltage / 50; + case LTC4245_5VSENSE: + /* Fixed point math: mV / 3.5 mOhm == mA */ + return (voltage * 35 + 5) / 10; + case LTC4245_3VSENSE: + /* Fixed point math: mV / 2.5 mOhm == mA */ + return (voltage * 25 + 5) / 10; + case LTC4245_VEESENSE: + return voltage / 100; + } + + /* If we get here, the developer messed up */ + WARN_ON_ONCE(1); + return 0; +} + +static ssize_t ltc4245_show_voltage(struct device *dev, + struct device_attribute *da, + char *buf) +{ + struct sensor_device_attribute *attr = to_sensor_dev_attr(da); + const u32 voltage = ltc4245_get_voltage(dev, attr->index); + + switch (attr->index) { + case LTC4245_12VIN: + case LTC4245_12VOUT: + case LTC4245_5VIN: + case LTC4245_5VOUT: + case LTC4245_3VIN: + case LTC4245_3VOUT: + case LTC4245_GPIOADC1: + case LTC4245_GPIOADC2: + case LTC4245_GPIOADC3: + return snprintf(buf, PAGE_SIZE, "%u\n", voltage); + case LTC4245_VEEIN: + case LTC4245_VEEOUT: + /* Vee (-12v) voltage is always negative */ + return snprintf(buf, PAGE_SIZE, "%d\n", voltage * -1); + } + + /* If we get here, the developer messed up :) */ + WARN_ON_ONCE(1); + return 0; +} + +static ssize_t ltc4245_show_current(struct device *dev, + struct device_attribute *da, + char *buf) +{ + struct sensor_device_attribute *attr = to_sensor_dev_attr(da); + const u32 current = ltc4245_get_current(dev, attr->index); + + return snprintf(buf, PAGE_SIZE, "%u\n", current); +} + +static ssize_t ltc4245_show_power(struct device *dev, + struct device_attribute *da, + char *buf) +{ + struct sensor_device_attribute *attr = to_sensor_dev_attr(da); + const u32 current = ltc4245_get_current(dev, attr->index); + const u32 output_voltage = ltc4245_get_voltage(dev, attr->index+1); + + return snprintf(buf, PAGE_SIZE, "%u\n", output_voltage * current); +} + +static ssize_t ltc4245_show_voltage_alarm(struct device *dev, + struct device_attribute *da, + char *buf) +{ + struct sensor_device_attribute *attr = to_sensor_dev_attr(da); + struct ltc4245_data *data = ltc4245_update_device(dev); + const s32 fault1 = data->cregs[LTC4245_FAULT1]; + int alarm = 0; + + if (unlikely(fault1 < 0)) { + memset(buf, 0, PAGE_SIZE); /* user should not see old data */ + return 0; + } + + switch (attr->index) { + case LTC4245_12VIN: + alarm = fault1 & (1 << 0); + break; + case LTC4245_5VIN: + alarm = fault1 & (1 << 1); + break; + case LTC4245_3VIN: + alarm = fault1 & (1 << 2); + break; + case LTC4245_VEEIN: + alarm = fault1 & (1 << 3); + break; + default: + /* If we get here, the developer messed up */ + WARN_ON_ONCE(1); + break; + } + + return snprintf(buf, PAGE_SIZE, "%d\n", alarm ? 1 : 0); +} + +static ssize_t ltc4245_show_current_alarm(struct device *dev, + struct device_attribute *da, + char *buf) +{ + struct sensor_device_attribute *attr = to_sensor_dev_attr(da); + struct ltc4245_data *data = ltc4245_update_device(dev); + const s32 fault1 = data->cregs[LTC4245_FAULT1]; + int alarm = 0; + + if (unlikely(fault1 < 0)) { + memset(buf, 0, PAGE_SIZE); /* user should not see old data */ + return 0; + } + + switch (attr->index) { + case LTC4245_12VSENSE: + alarm = fault1 & (1 << 4); + break; + case LTC4245_5VSENSE: + alarm = fault1 & (1 << 5); + break; + case LTC4245_3VSENSE: + alarm = fault1 & (1 << 6); + break; + case LTC4245_VEESENSE: + alarm = fault1 & (1 << 7); + break; + default: + /* If we get here, the developer messed up */ + WARN_ON_ONCE(1); + break; + } + + return snprintf(buf, PAGE_SIZE, "%d\n", alarm ? 1 : 0); +} + +static ssize_t ltc4245_show_power_alarm(struct device *dev, + struct device_attribute *da, + char *buf) +{ + struct sensor_device_attribute *attr = to_sensor_dev_attr(da); + struct ltc4245_data *data = ltc4245_update_device(dev); + const s32 fault2 = data->cregs[LTC4245_FAULT2]; + int alarm = 0; + + if (unlikely(fault2 < 0)) { + memset(buf, 0, PAGE_SIZE); /* user should not see old data */ + return 0; + } + + switch (attr->index) { + case LTC4245_12VOUT: + alarm = fault2 & (1 << 0); + break; + case LTC4245_5VOUT: + alarm = fault2 & (1 << 1); + break; + case LTC4245_3VOUT: + alarm = fault2 & (1 << 2); + break; + case LTC4245_VEEOUT: + alarm = fault2 & (1 << 3); + break; + default: + /* If we get here, the developer messed up */ + WARN_ON_ONCE(1); + break; + } + + return snprintf(buf, PAGE_SIZE, "%d\n", alarm ? 1 : 0); +} + +/* These macros are used below in constructing device attribute objects + * for use with sysfs_create_group() to make a sysfs device file + * for each register. + */ +#define LTC4245_VOLTAGE_RO(name, ltc4245_cmd_idx) \ + static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ + ltc4245_show_voltage, NULL, ltc4245_cmd_idx) + +#define LTC4245_CURRENT_RO(name, ltc4245_cmd_idx) \ + static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ + ltc4245_show_current, NULL, ltc4245_cmd_idx) + +#define LTC4245_POWER_RO(name, ltc4245_cmd_idx) \ + static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ + ltc4245_show_power, NULL, ltc4245_cmd_idx) + +#define LTC4245_VOLTAGE_ALARM(name, ltc4245_cmd_idx) \ + static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ + ltc4245_show_voltage_alarm, NULL, ltc4245_cmd_idx) + +#define LTC4245_CURRENT_ALARM(name, ltc4245_cmd_idx) \ + static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ + ltc4245_show_current_alarm, NULL, ltc4245_cmd_idx) + +#define LTC4245_POWER_ALARM(name, ltc4245_cmd_idx) \ + static SENSOR_DEVICE_ATTR(name, S_IRUGO, \ + ltc4245_show_power_alarm, NULL, ltc4245_cmd_idx) + +/* Construct a sensor_device_attribute structure for each register */ + +/* Input voltages */ +LTC4245_VOLTAGE_RO(in1_input, LTC4245_12VIN); +LTC4245_VOLTAGE_RO(in2_input, LTC4245_5VIN); +LTC4245_VOLTAGE_RO(in3_input, LTC4245_3VIN); +LTC4245_VOLTAGE_RO(in4_input, LTC4245_VEEIN); + +/* Input undervoltage alarms */ +LTC4245_VOLTAGE_ALARM(in1_min_alarm, LTC4245_12VIN); +LTC4245_VOLTAGE_ALARM(in2_min_alarm, LTC4245_5VIN); +LTC4245_VOLTAGE_ALARM(in3_min_alarm, LTC4245_3VIN); +LTC4245_VOLTAGE_ALARM(in4_min_alarm, LTC4245_VEEIN); + +/* Currents (via sense resistor) */ +LTC4245_CURRENT_RO(curr1_input, LTC4245_12VSENSE); +LTC4245_CURRENT_RO(curr2_input, LTC4245_5VSENSE); +LTC4245_CURRENT_RO(curr3_input, LTC4245_3VSENSE); +LTC4245_CURRENT_RO(curr4_input, LTC4245_VEESENSE); + +/* Overcurrent alarms */ +LTC4245_CURRENT_ALARM(curr1_max_alarm, LTC4245_12VSENSE); +LTC4245_CURRENT_ALARM(curr2_max_alarm, LTC4245_5VSENSE); +LTC4245_CURRENT_ALARM(curr3_max_alarm, LTC4245_3VSENSE); +LTC4245_CURRENT_ALARM(curr4_max_alarm, LTC4245_VEESENSE); + +/* Output voltages */ +LTC4245_VOLTAGE_RO(in5_input, LTC4245_12VOUT); +LTC4245_VOLTAGE_RO(in6_input, LTC4245_5VOUT); +LTC4245_VOLTAGE_RO(in7_input, LTC4245_3VOUT); +LTC4245_VOLTAGE_RO(in8_input, LTC4245_VEEOUT); + +/* GPIO voltages */ +LTC4245_VOLTAGE_RO(in9_input, LTC4245_GPIOADC1); +LTC4245_VOLTAGE_RO(in10_input, LTC4245_GPIOADC2); +LTC4245_VOLTAGE_RO(in11_input, LTC4245_GPIOADC3); + +/* Power Consumption (virtual) */ +LTC4245_POWER_RO(power1_input, LTC4245_12VSENSE); +LTC4245_POWER_RO(power2_input, LTC4245_5VSENSE); +LTC4245_POWER_RO(power3_input, LTC4245_3VSENSE); +LTC4245_POWER_RO(power4_input, LTC4245_VEESENSE); + +/* Power Bad alarms */ +LTC4245_POWER_ALARM(power1_alarm, LTC4245_12VOUT); +LTC4245_POWER_ALARM(power2_alarm, LTC4245_5VOUT); +LTC4245_POWER_ALARM(power3_alarm, LTC4245_3VOUT); +LTC4245_POWER_ALARM(power4_alarm, LTC4245_VEEOUT); + +/* Finally, construct an array of pointers to members of the above objects, + * as required for sysfs_create_group() + */ +static struct attribute *ltc4245_attributes[] = { + &sensor_dev_attr_in1_input.dev_attr.attr, + &sensor_dev_attr_in2_input.dev_attr.attr, + &sensor_dev_attr_in3_input.dev_attr.attr, + &sensor_dev_attr_in4_input.dev_attr.attr, + + &sensor_dev_attr_in1_min_alarm.dev_attr.attr, + &sensor_dev_attr_in2_min_alarm.dev_attr.attr, + &sensor_dev_attr_in3_min_alarm.dev_attr.attr, + &sensor_dev_attr_in4_min_alarm.dev_attr.attr, + + &sensor_dev_attr_curr1_input.dev_attr.attr, + &sensor_dev_attr_curr2_input.dev_attr.attr, + &sensor_dev_attr_curr3_input.dev_attr.attr, + &sensor_dev_attr_curr4_input.dev_attr.attr, + + &sensor_dev_attr_curr1_max_alarm.dev_attr.attr, + &sensor_dev_attr_curr2_max_alarm.dev_attr.attr, + &sensor_dev_attr_curr3_max_alarm.dev_attr.attr, + &sensor_dev_attr_curr4_max_alarm.dev_attr.attr, + + &sensor_dev_attr_in5_input.dev_attr.attr, + &sensor_dev_attr_in6_input.dev_attr.attr, + &sensor_dev_attr_in7_input.dev_attr.attr, + &sensor_dev_attr_in8_input.dev_attr.attr, + + &sensor_dev_attr_in9_input.dev_attr.attr, + &sensor_dev_attr_in10_input.dev_attr.attr, + &sensor_dev_attr_in11_input.dev_attr.attr, + + &sensor_dev_attr_power1_input.dev_attr.attr, + &sensor_dev_attr_power2_input.dev_attr.attr, + &sensor_dev_attr_power3_input.dev_attr.attr, + &sensor_dev_attr_power4_input.dev_attr.attr, + + &sensor_dev_attr_power1_alarm.dev_attr.attr, + &sensor_dev_attr_power2_alarm.dev_attr.attr, + &sensor_dev_attr_power3_alarm.dev_attr.attr, + &sensor_dev_attr_power4_alarm.dev_attr.attr, + + NULL, +}; + +static struct attribute_group ltc4245_group = { + .attrs = ltc4245_attributes, +}; + +static int ltc4245_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct ltc4245_data *data; + int ret; + + data = kzalloc(sizeof(*data), GFP_KERNEL); + + if (!data) { + ret = -ENOMEM; + goto out_kzalloc; + } + + i2c_set_clientdata(client, data); + mutex_init(&data->update_lock); + + /* Initialize the LTC4245 chip */ + /* TODO */ + + /* Register sysfs hooks */ + ret = sysfs_create_group(&client->dev.kobj, <c4245_group); + + if (ret) + goto out_sysfs_create_group; + + data->hwmon_dev = hwmon_device_register(&client->dev); + + if (IS_ERR(data->hwmon_dev)) { + ret = PTR_ERR(data->hwmon_dev); + goto out_hwmon_device_register; + } + + return 0; + +out_hwmon_device_register: + sysfs_remove_group(&client->dev.kobj, <c4245_group); +out_sysfs_create_group: + kfree(data); +out_kzalloc: + return ret; +} + +static int ltc4245_remove(struct i2c_client *client) +{ + struct ltc4245_data *data = i2c_get_clientdata(client); + + hwmon_device_unregister(data->hwmon_dev); + sysfs_remove_group(&client->dev.kobj, <c4245_group); + + kfree(data); + + return 0; +} + +/* Check that some bits in a control register appear at all possible + * locations without changing value + * + * @client: the i2c client to use + * @reg: the register to read + * @bits: the bits to check (0xff checks all bits, + * 0x03 checks only the last two bits) + * + * return -ENODEV if the register value doesn't stay constant at all + * possible addresses + * + * return 0 for success + */ +static int ltc4245_check_control_reg(struct i2c_client *client, u8 reg, u8 bits) +{ + int i; + s32 v, voff1, voff2; + + v = ltc4245_read_reg(client, reg) & bits; + + if (v < 0) + return -ENODEV; + + for (i = 0x00; i < 0xff; i += 0x20) { + voff1 = ltc4245_read_reg(client, reg + i) & bits; + voff2 = ltc4245_read_reg(client, reg + i + 0x08) & bits; + + if (voff1 < 0 || voff2 < 0 || v != voff1 || v != voff2) + return -ENODEV; + } + + return 0; +} + +static int ltc4245_detect(struct i2c_client *client, + int kind, + struct i2c_board_info *info) +{ + struct i2c_adapter *adapter = client->adapter; + + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) + return -ENODEV; + + if (kind < 0) { /* probed detection - check the chip type */ + s32 v; /* 8 bits from the chip, or -ERRNO */ + + /* Chip registers 0x00-0x07 are control registers + * Chip registers 0x10-0x1f are data registers + * + * Address bits b7-b5 are ignored. This makes the chip "repeat" + * in steps of 0x20. Any control registers should appear with + * the same values across all duplicated addresses. + * + * Register 0x02 bit b2 is reserved, expect 0 + * Register 0x07 bits b7 to b4 are reserved, expect 0 + * + * Registers 0x01, 0x02 are control registers and should not + * change on their own. + * + * Register 0x06 bits b6 and b7 are control bits, and should + * not change on their own. + * + * Register 0x07 bits b3 to b0 are control bits, and should + * not change on their own. + */ + + /* read register 0x02 reserved bit, expect 0 */ + v = ltc4245_read_reg(client, LTC4245_CONTROL); + if (v < 0 || (v & 0x04) != 0) + return -ENODEV; + + /* read register 0x07 reserved bits, expect 0 */ + v = ltc4245_read_reg(client, LTC4245_ADCADR); + if (v < 0 || (v & 0xf0) != 0) + return -ENODEV; + + /* check that the alert register appears at all locations */ + if (ltc4245_check_control_reg(client, LTC4245_ALERT, 0xff)) + return -ENODEV; + + /* check that the control register appears at all locations */ + if (ltc4245_check_control_reg(client, LTC4245_CONTROL, 0xff)) + return -ENODEV; + + /* check that register 0x06 bits b6 and b7 stay constant */ + if (ltc4245_check_control_reg(client, LTC4245_GPIO, 0xc0)) + return -ENODEV; + + /* check that register 0x07 bits b3-b0 stay constant */ + if (ltc4245_check_control_reg(client, LTC4245_ADCADR, 0x0f)) + return -ENODEV; + } + + strlcpy(info->type, "ltc4245", I2C_NAME_SIZE); + pr_info("ltc4245: %s on i2c-%u address 0x%02x\n", + kind < 0 ? "probed" : "forced", + adapter->nr, client->addr); + + return 0; +} + +static const struct i2c_device_id ltc4245_id[] = { + { "ltc4245", ltc4245 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, ltc4245_id); + +/* This is the driver that will be inserted */ +static struct i2c_driver ltc4245_driver = { + .class = I2C_CLASS_HWMON, + .driver = { + .name = "ltc4245", + }, + .probe = ltc4245_probe, + .remove = ltc4245_remove, + .id_table = ltc4245_id, + .detect = ltc4245_detect, + .address_data = &addr_data, +}; + +static int __init ltc4245_init(void) +{ + return i2c_add_driver(<c4245_driver); +} + +static void __exit ltc4245_exit(void) +{ + i2c_del_driver(<c4245_driver); +} + +MODULE_AUTHOR("Ira W. Snyder <iws at ovro.caltech.edu>"); +MODULE_DESCRIPTION("LTC4245 driver"); +MODULE_LICENSE("GPL"); + +module_init(ltc4245_init); +module_exit(ltc4245_exit); -- 1.5.4.3
