mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-23 17:30:02 +00:00
![Zev Weiss](/assets/img/avatar_default.png)
This driver provides an i2c I/O mechanism for the core nct6775 driver, as might be used by a BMC. Because the Super I/O chip is shared with the host CPU in such a scenario (and the host should ultimately be in control of it), the i2c driver is strictly read-only to avoid interfering with any usage by the host (aside from the bank-select register, which seems to be replicated for the i2c interface). Signed-off-by: Zev Weiss <zev@bewilderbeest.net> Tested-by: Renze Nicolai <renze@rnplus.nl> Link: https://lore.kernel.org/r/20220428012707.24921-3-zev@bewilderbeest.net Signed-off-by: Guenter Roeck <linux@roeck-us.net>
195 lines
6 KiB
C
195 lines
6 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* nct6775-i2c - I2C driver for the hardware monitoring functionality of
|
|
* Nuvoton NCT677x Super-I/O chips
|
|
*
|
|
* Copyright (C) 2022 Zev Weiss <zev@bewilderbeest.net>
|
|
*
|
|
* This driver interacts with the chip via it's "back door" i2c interface, as
|
|
* is often exposed to a BMC. Because the host may still be operating the
|
|
* chip via the ("front door") LPC interface, this driver cannot assume that
|
|
* it actually has full control of the chip, and in particular must avoid
|
|
* making any changes that could confuse the host's LPC usage of it. It thus
|
|
* operates in a strictly read-only fashion, with the only exception being the
|
|
* bank-select register (which seems, thankfully, to be replicated for the i2c
|
|
* interface so it doesn't affect the LPC interface).
|
|
*/
|
|
|
|
#include <linux/module.h>
|
|
#include <linux/init.h>
|
|
#include <linux/i2c.h>
|
|
#include <linux/hwmon.h>
|
|
#include <linux/hwmon-sysfs.h>
|
|
#include <linux/err.h>
|
|
#include <linux/of_device.h>
|
|
#include <linux/regmap.h>
|
|
#include "nct6775.h"
|
|
|
|
static int nct6775_i2c_read(void *ctx, unsigned int reg, unsigned int *val)
|
|
{
|
|
int ret;
|
|
u32 tmp;
|
|
u8 bank = reg >> 8;
|
|
struct nct6775_data *data = ctx;
|
|
struct i2c_client *client = data->driver_data;
|
|
|
|
if (bank != data->bank) {
|
|
ret = i2c_smbus_write_byte_data(client, NCT6775_REG_BANK, bank);
|
|
if (ret)
|
|
return ret;
|
|
data->bank = bank;
|
|
}
|
|
|
|
ret = i2c_smbus_read_byte_data(client, reg & 0xff);
|
|
if (ret < 0)
|
|
return ret;
|
|
tmp = ret;
|
|
|
|
if (nct6775_reg_is_word_sized(data, reg)) {
|
|
ret = i2c_smbus_read_byte_data(client, (reg & 0xff) + 1);
|
|
if (ret < 0)
|
|
return ret;
|
|
tmp = (tmp << 8) | ret;
|
|
}
|
|
|
|
*val = tmp;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* The write operation is a dummy so as not to disturb anything being done
|
|
* with the chip via LPC.
|
|
*/
|
|
static int nct6775_i2c_write(void *ctx, unsigned int reg, unsigned int value)
|
|
{
|
|
struct nct6775_data *data = ctx;
|
|
struct i2c_client *client = data->driver_data;
|
|
|
|
dev_dbg(&client->dev, "skipping attempted write: %02x -> %03x\n", value, reg);
|
|
|
|
/*
|
|
* This is a lie, but writing anything but the bank-select register is
|
|
* something this driver shouldn't be doing.
|
|
*/
|
|
return 0;
|
|
}
|
|
|
|
static const struct of_device_id __maybe_unused nct6775_i2c_of_match[] = {
|
|
{ .compatible = "nuvoton,nct6106", .data = (void *)nct6106, },
|
|
{ .compatible = "nuvoton,nct6116", .data = (void *)nct6116, },
|
|
{ .compatible = "nuvoton,nct6775", .data = (void *)nct6775, },
|
|
{ .compatible = "nuvoton,nct6776", .data = (void *)nct6776, },
|
|
{ .compatible = "nuvoton,nct6779", .data = (void *)nct6779, },
|
|
{ .compatible = "nuvoton,nct6791", .data = (void *)nct6791, },
|
|
{ .compatible = "nuvoton,nct6792", .data = (void *)nct6792, },
|
|
{ .compatible = "nuvoton,nct6793", .data = (void *)nct6793, },
|
|
{ .compatible = "nuvoton,nct6795", .data = (void *)nct6795, },
|
|
{ .compatible = "nuvoton,nct6796", .data = (void *)nct6796, },
|
|
{ .compatible = "nuvoton,nct6797", .data = (void *)nct6797, },
|
|
{ .compatible = "nuvoton,nct6798", .data = (void *)nct6798, },
|
|
{ },
|
|
};
|
|
MODULE_DEVICE_TABLE(of, nct6775_i2c_of_match);
|
|
|
|
static const struct i2c_device_id nct6775_i2c_id[] = {
|
|
{ "nct6106", nct6106 },
|
|
{ "nct6116", nct6116 },
|
|
{ "nct6775", nct6775 },
|
|
{ "nct6776", nct6776 },
|
|
{ "nct6779", nct6779 },
|
|
{ "nct6791", nct6791 },
|
|
{ "nct6792", nct6792 },
|
|
{ "nct6793", nct6793 },
|
|
{ "nct6795", nct6795 },
|
|
{ "nct6796", nct6796 },
|
|
{ "nct6797", nct6797 },
|
|
{ "nct6798", nct6798 },
|
|
{ }
|
|
};
|
|
MODULE_DEVICE_TABLE(i2c, nct6775_i2c_id);
|
|
|
|
static int nct6775_i2c_probe_init(struct nct6775_data *data)
|
|
{
|
|
u32 tsi_channel_mask;
|
|
struct i2c_client *client = data->driver_data;
|
|
|
|
/*
|
|
* The i2c interface doesn't provide access to the control registers
|
|
* needed to determine the presence of other fans, but fans 1 and 2
|
|
* are (in principle) always there.
|
|
*
|
|
* In practice this is perhaps a little silly, because the system
|
|
* using this driver is mostly likely a BMC, and hence probably has
|
|
* totally separate fan tachs & pwms of its own that are actually
|
|
* controlling/monitoring the fans -- these are thus unlikely to be
|
|
* doing anything actually useful.
|
|
*/
|
|
data->has_fan = 0x03;
|
|
data->has_fan_min = 0x03;
|
|
data->has_pwm = 0x03;
|
|
|
|
/*
|
|
* Because on a BMC this driver may be bound very shortly after power
|
|
* is first applied to the device, the automatic TSI channel detection
|
|
* in nct6775_probe() (which has already been run at this point) may
|
|
* not find anything if a channel hasn't yet produced a temperature
|
|
* reading. Augment whatever was found via autodetection (if
|
|
* anything) with the channels DT says should be active.
|
|
*/
|
|
if (!of_property_read_u32(client->dev.of_node, "nuvoton,tsi-channel-mask",
|
|
&tsi_channel_mask))
|
|
data->have_tsi_temp |= tsi_channel_mask & GENMASK(NUM_TSI_TEMP - 1, 0);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct regmap_config nct6775_i2c_regmap_config = {
|
|
.reg_bits = 16,
|
|
.val_bits = 16,
|
|
.reg_read = nct6775_i2c_read,
|
|
.reg_write = nct6775_i2c_write,
|
|
};
|
|
|
|
static int nct6775_i2c_probe(struct i2c_client *client)
|
|
{
|
|
struct nct6775_data *data;
|
|
const struct of_device_id *of_id;
|
|
const struct i2c_device_id *i2c_id;
|
|
struct device *dev = &client->dev;
|
|
|
|
of_id = of_match_device(nct6775_i2c_of_match, dev);
|
|
i2c_id = i2c_match_id(nct6775_i2c_id, client);
|
|
|
|
if (of_id && (unsigned long)of_id->data != i2c_id->driver_data)
|
|
dev_notice(dev, "Device mismatch: %s in device tree, %s detected\n",
|
|
of_id->name, i2c_id->name);
|
|
|
|
data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
|
|
if (!data)
|
|
return -ENOMEM;
|
|
|
|
data->kind = i2c_id->driver_data;
|
|
|
|
data->read_only = true;
|
|
data->driver_data = client;
|
|
data->driver_init = nct6775_i2c_probe_init;
|
|
|
|
return nct6775_probe(dev, data, &nct6775_i2c_regmap_config);
|
|
}
|
|
|
|
static struct i2c_driver nct6775_i2c_driver = {
|
|
.class = I2C_CLASS_HWMON,
|
|
.driver = {
|
|
.name = "nct6775-i2c",
|
|
.of_match_table = of_match_ptr(nct6775_i2c_of_match),
|
|
},
|
|
.probe_new = nct6775_i2c_probe,
|
|
.id_table = nct6775_i2c_id,
|
|
};
|
|
|
|
module_i2c_driver(nct6775_i2c_driver);
|
|
|
|
MODULE_AUTHOR("Zev Weiss <zev@bewilderbeest.net>");
|
|
MODULE_DESCRIPTION("I2C driver for NCT6775F and compatible chips");
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_IMPORT_NS(HWMON_NCT6775);
|