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