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Date: Mon, 8 Jun 2020 07:03:03 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Álvaro Fernández Rojas <noltari@...il.com>,
jdelvare@...e.com, thierry.reding@...il.com,
u.kleine-koenig@...gutronix.de, linux-kernel@...r.kernel.org,
linux-hwmon@...r.kernel.org, linux-pwm@...r.kernel.org
Subject: Re: [PATCH 2/2] hwmon: Add SFR NB6 sensor driver
On 6/7/20 11:25 AM, Álvaro Fernández Rojas wrote:
> SFR NeufBox 6 is equipped with an I2C connected chip to monitor voltage,
> temperature and other stats. It also has a PWM LEDs that can be manually
> controlled or set to specific hardware monitoring modes.
>
> Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
> ---
> drivers/hwmon/Kconfig | 11 +
> drivers/hwmon/Makefile | 1 +
> drivers/hwmon/nb6-hwmon.c | 466 ++++++++++++++++++++++++++++++++++++++
Missing Documentation/hwmon/nb6-hwmon.rst
> 3 files changed, 478 insertions(+)
> create mode 100644 drivers/hwmon/nb6-hwmon.c
>
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 288ae9f63588..5523de75868d 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -1092,6 +1092,17 @@ config SENSORS_MENF21BMC_HWMON
> This driver can also be built as a module. If so the module
> will be called menf21bmc_hwmon.
>
> +config SENSORS_NB6_HWMON
> + tristate "SFR NeufBox 6 (NB6) Hardware Monitoring"
> + depends on I2C
> + depends on PWM
> + help
> + If you say yes here you get support for SFR NeufBox 6 PWM LEDs,
> + temperature and voltage sensors.
> +
This driver should not support LEDs.
> + This driver can also be built as a module. If so, the module
> + will be called nb6-hwmon.
> +
> config SENSORS_ADCXX
> tristate "National Semiconductor ADCxxxSxxx"
> depends on SPI_MASTER
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 3e32c21f5efe..5a35fde42bd8 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -141,6 +141,7 @@ obj-$(CONFIG_SENSORS_MCP3021) += mcp3021.o
> obj-$(CONFIG_SENSORS_TC654) += tc654.o
> obj-$(CONFIG_SENSORS_MLXREG_FAN) += mlxreg-fan.o
> obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
> +obj-$(CONFIG_SENSORS_NB6_HWMON) += nb6-hwmon.o
> obj-$(CONFIG_SENSORS_NCT6683) += nct6683.o
> obj-$(CONFIG_SENSORS_NCT6775) += nct6775.o
> obj-$(CONFIG_SENSORS_NCT7802) += nct7802.o
> diff --git a/drivers/hwmon/nb6-hwmon.c b/drivers/hwmon/nb6-hwmon.c
> new file mode 100644
> index 000000000000..aebb6ebbf3a8
> --- /dev/null
> +++ b/drivers/hwmon/nb6-hwmon.c
> @@ -0,0 +1,466 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Driver for SFR NeufBox 6 Hardware Monitoring
> + *
> + * Copyright 2020 Álvaro Fernández Rojas <noltari@...il.com>
> + */
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/hwmon.h>
> +#include <linux/err.h>
> +#include <linux/mutex.h>
> +#include <linux/pwm.h>
> +#include <linux/sysfs.h>
> +
> +#define NB6_LEDS_PWM_REG 0x10
> +#define NB6_TEMP_REG 0x22
> +#define NB6_VOLTAGE_REG 0x24
> +#define NB6_DMESG_CTL_REG 0x26
> +#define NB6_DMESG_VAL_REG 0x27
> +#define NB6_LEDS_MODE_REG 0x31
> +#define NB6_RELEASE_REG 0x90
> +#define NB6_STATS_BOOT_REG 0xa0
> +#define NB6_STATS_PANIC_REG 0xa1
> +#define NB6_STATS_OOPS_REG 0xa2
> +#define NB6_WDT_REG 0xee
> +
> +#define NB6_DELAY 1000
> +#define NB6_DMESG_SIZE 512
> +#define NB6_I2C_RETRIES 5
> +#define NB6_LEDS_MODE_LEN 32
> +#define NB6_LEDS_PWM_COUNT 9
> +#define NB6_PWM(x) (NB6_LEDS_PWM_REG + x)
> +#define NB6_WDT_LEN 10
> +
> +#define ADC_quantum(Vref) ((1000 * (Vref)) / 1024)
> +#define ADC_mV(Vref,x) ((ADC_quantum(Vref) * (x)) / 1000)
> +#define ADC_Temperature(t) (1000 * (100 * ADC_mV(1800, t)) / 349)
> +#define MR1 82
> +#define MR2 20
> +#define ADC_Voltage(v) ((ADC_mV(2400, v) * ((10 * (MR1 + MR2)) / MR2)) / 10)
> +
> +struct nb6_data {
> + struct pwm_chip pwm;
> + struct i2c_client *i2c;
> + struct device *dev;
> + struct mutex lock;
> + u8 leds_mode;
> + u8 leds_pwm[NB6_LEDS_PWM_COUNT];
> + u8 release;
> + u8 stats_boot;
> + u8 stats_panic;
> + u8 stats_oops;
> + u16 temperature;
> + u16 voltage;
> + u8 watchdog;
> +};
> +
> +enum LEDS_MODE {
> + LEDS_MODE_DISABLE,
> + LEDS_MODE_BOOT,
> + LEDS_MODE_BOOT_MAIN,
> + LEDS_MODE_BOOT_TFTP,
> + LEDS_MODE_BOOT_RESCUE,
> + LEDS_MODE_LOGIN,
> + LEDS_MODE_BURNING,
> + LEDS_MODE_DOWNLOAD,
> + LEDS_MODE_WDT_TEMPERATURE,
> + LEDS_MODE_WDT_VOLTAGE,
> + LEDS_MODE_PANIC,
> + LEDS_MODE_CONTROL,
> + LEDS_MODE_NUM
> +};
> +
> +static char const *leds_modes_str[] = {
> + [LEDS_MODE_DISABLE] = "disable",
> + [LEDS_MODE_BOOT] = "boot",
> + [LEDS_MODE_BOOT_MAIN] = "boot-main",
> + [LEDS_MODE_BOOT_TFTP] = "boot-tftp",
> + [LEDS_MODE_BOOT_RESCUE] = "boot-rescue",
> + [LEDS_MODE_LOGIN] = "login",
> + [LEDS_MODE_BURNING] = "burning",
> + [LEDS_MODE_DOWNLOAD] = "downloading",
> + [LEDS_MODE_WDT_TEMPERATURE] = "wdt-temperature",
> + [LEDS_MODE_WDT_VOLTAGE] = "wdt-voltage",
> + [LEDS_MODE_PANIC] = "panic",
> + [LEDS_MODE_CONTROL] = "control",
> +};
> +
> +/* I2C Helpers */
> +
> +static u8 nb6_readb(struct nb6_data *data, u8 addr, u8 val)
This will never return an error.
> +{
> + int status;
> + unsigned i;
> +
> + for (i = 0; i < NB6_I2C_RETRIES; i++) {
> + status = i2c_smbus_read_byte_data(data->i2c, addr);
> + if (status >= 0)
> + return status;
> + udelay(NB6_DELAY);
> + }
> +
Is that system really that bad ? That needs an explanation.
> + dev_err(data->dev, "read error (%d): addr=0x%02x", status, addr);
> +
> + return val;
Obviously this error case was never reached.
> +}
> +
> +static u16 nb6_readw(struct nb6_data *data, u8 addr, u16 val)
This will never return an error.
> +{
> + u8 tmp;
> +
> + tmp = nb6_readb(data, addr, (val >> 8) & 0xff);
This ignores any received errors and, worse, converts errors
into pretty much random data.
> + val = (val & 0xff) | (tmp << 8);
> +
> + tmp = nb6_readb(data, addr + 1, val & 0xff);
> + val = (val & 0xff00) | tmp;
> +
> + return val;
> +}
> +
> +static s32 nb6_writeb(struct nb6_data *data, u8 addr, u8 val)
> +{
> + int status;
> + unsigned i;
> +
> + for (i = 0; i < NB6_I2C_RETRIES; i++) {
> + status = i2c_smbus_write_byte_data(data->i2c, addr, val);
> + if (!status)
> + return 0;
> + udelay(NB6_DELAY);
> + }
> +
> + dev_err(data->dev, "write error (%d): addr=0x%02x val=0x%02x", status, addr, val);
> +
> + return status;
> +}
> +
> +static inline void leds_mode_update(struct nb6_data *data, u8 val)
> +{
> + if ((data->leds_mode != val) &&
> + !nb6_writeb(data, NB6_LEDS_MODE_REG, val))
> + data->leds_mode = val;
> +}
> +
> +static inline void leds_pwm_update(struct nb6_data *data, u8 id, u8 val)
> +{
> + if ((data->leds_pwm[id] != val) &&
> + !nb6_writeb(data, NB6_PWM(id), val))
> + data->leds_pwm[id] = val;
> +}
> +
> +/* Hardware Monitoring */
> +
> +static ssize_t dmesg_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> + unsigned i;
> +
> + mutex_lock(&data->lock);
> +
> + if (nb6_writeb(data, NB6_DMESG_CTL_REG, 0)) {
> + mutex_unlock(&data->lock);
> + return -EINVAL;
> + }
> +
> + for (i = 0; i < NB6_DMESG_SIZE; i++)
> + buf[i] = nb6_readb(data, NB6_DMESG_VAL_REG, ~0);
> +
> + mutex_unlock(&data->lock);
> +
> + *buf = '\0';
> +
> + return i + 1;
> +}
> +
> +static DEVICE_ATTR_RO(dmesg);
> +
Non-standard attributes need to be explained and their need must be discussed.
> +static ssize_t leds_mode_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> + loff_t off = 0;
> + unsigned i;
> +
> + mutex_lock(&data->lock);
> + data->leds_mode = nb6_readb(data, NB6_LEDS_MODE_REG, data->leds_mode);
> + mutex_unlock(&data->lock);
> +
> + for (i = 0; i < ARRAY_SIZE(leds_modes_str); i++) {
> + off += sprintf(buf + off,
> + (i == data->leds_mode) ? "[%s] " : "%s ",
> + leds_modes_str[i]);
> + }
> +
> + off += sprintf(buf + off, "\n");
> +
> + return off;
> +}
> +
> +static ssize_t leds_mode_store(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf, size_t count)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> + char _s[NB6_LEDS_MODE_LEN];
> + char *s;
> + unsigned i;
> +
> + snprintf(_s, sizeof(_s), "%s", buf);
> + s = strstrip(_s);
> + for (i = 0; i < ARRAY_SIZE(leds_modes_str); i++) {
> + if (!strcmp(s, leds_modes_str[i])) {
> + leds_mode_update(data, i);
> + break;
> + }
> + }
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR_RW(leds_mode);
> +
I won't accept any attributes not associated with hardware monitoring.
> +static ssize_t release_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> +
> + mutex_lock(&data->lock);
> + data->release = nb6_readb(data, NB6_RELEASE_REG, data->release);
> + mutex_unlock(&data->lock);
> +
> + return sprintf(buf, "%u\n", data->release);
> +}
> +
> +static DEVICE_ATTR_RO(release);
> +
And I will most definitely not accept unexplained non-standard attributes.
> +static ssize_t stats_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> +
> + mutex_lock(&data->lock);
> + data->stats_boot = nb6_readb(data, NB6_STATS_BOOT_REG,
> + data->stats_boot);
> + data->stats_panic = nb6_readb(data, NB6_STATS_PANIC_REG,
> + data->stats_panic);
> + data->stats_oops = nb6_readb(data, NB6_STATS_OOPS_REG,
> + data->stats_oops);
> + mutex_unlock(&data->lock);
> +
> + return sprintf(buf, "boot: %u\npanic: %u\noops: %u\n",
> + data->stats_boot, data->stats_panic, data->stats_oops);
> +}
> +
> +static DEVICE_ATTR_RO(stats);
> +
> +static ssize_t temperature_show(struct device *dev,
> + struct device_attribute *da, char *buf)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> +
> + mutex_lock(&data->lock);
> + data->temperature = nb6_readw(data, NB6_TEMP_REG, data->temperature);
> + mutex_unlock(&data->lock);
> +
> + return sprintf(buf, "%u\n", ADC_Temperature(data->temperature));
> +}
> +
> +static DEVICE_ATTR_RO(temperature);
> +
> +static ssize_t voltage_show(struct device *dev, struct device_attribute *attr,
> + char *buf)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> +
> + mutex_lock(&data->lock);
> + data->voltage = nb6_readw(data, NB6_VOLTAGE_REG, data->voltage);
> + mutex_unlock(&data->lock);
> +
> + return sprintf(buf, "%u\n", ADC_Voltage(data->voltage));
> +}
> +
> +static DEVICE_ATTR_RO(voltage);
> +
This are not standard hardware monitoring attributes.
> +static ssize_t watchdog_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> +
> + mutex_lock(&data->lock);
> + data->watchdog = nb6_readb(data, NB6_WDT_REG, data->watchdog);
> + mutex_unlock(&data->lock);
> +
> + return sprintf(buf, "%u\n", data->watchdog);
> +}
> +
> +static ssize_t watchdog_store(struct device *dev,
> + struct device_attribute *attr, const char *buf,
> + size_t len)
> +{
> + struct nb6_data *data = dev_get_drvdata(dev);
> + unsigned long val;
> + int ret;
> +
> + ret = kstrtoul(buf, 0, &val);
> + if (ret < 0)
> + return ret;
> +
> + mutex_lock(&data->lock);
> + if (!nb6_writeb(data, NB6_WDT_REG, val))
> + data->watchdog = val;
> + mutex_unlock(&data->lock);
> +
> + return len;
> +}
> +
> +static DEVICE_ATTR_RW(watchdog);
> +
While there are situations where we accept a watchdog driver as part
of a hardware monitoring driver, it has to be a standard watchdog
driver, not a random attribute such as "watchdog" and "status".
> +static struct attribute *nb6_attrs[] = {
> + &dev_attr_dmesg.attr,
> + &dev_attr_leds_mode.attr,
> + &dev_attr_release.attr,
> + &dev_attr_stats.attr,
> + &dev_attr_temperature.attr,
> + &dev_attr_voltage.attr,
> + &dev_attr_watchdog.attr,
> + NULL,
> +};
Not a single standard hardware monitoring attribute.
> +
> +ATTRIBUTE_GROUPS(nb6);
> +
> +/* PWM */
> +
> +static inline struct nb6_data *to_nb6_pwm(struct pwm_chip *chip)
> +{
> + return container_of(chip, struct nb6_data, pwm);
> +}
> +
> +static int nb6_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct nb6_data *data = to_nb6_pwm(chip);
> +
> + mutex_lock(&data->lock);
> + if (!nb6_writeb(data, NB6_PWM(pwm->hwpwm), 0))
> + data->leds_pwm[pwm->hwpwm] = 0;
> + else
> + data->leds_pwm[pwm->hwpwm] = ~0;
> + mutex_unlock(&data->lock);
> +
> + return 0;
> +}
> +
> +static void nb6_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct nb6_data *data = to_nb6_pwm(chip);
> + unsigned i;
> +
> + mutex_lock(&data->lock);
> + for (i = 0; i < NB6_LEDS_PWM_COUNT; i++) {
> + if (data->leds_pwm[i]) {
> + leds_mode_update(data, LEDS_MODE_DISABLE);
> + break;
> + }
> + }
> + mutex_unlock(&data->lock);
> +}
> +
> +static int nb6_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
> + int duty_ns, int period_ns)
> +{
> + struct nb6_data *data = to_nb6_pwm(chip);
> +
> + mutex_lock(&data->lock);
> + leds_mode_update(data, LEDS_MODE_CONTROL);
> + leds_pwm_update(data, pwm->hwpwm, duty_ns);
> + mutex_unlock(&data->lock);
> +
> + return 0;
> +}
> +
> +static int nb6_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct nb6_data *data = to_nb6_pwm(chip);
> +
> + mutex_lock(&data->lock);
> + leds_mode_update(data, LEDS_MODE_CONTROL);
> + mutex_unlock(&data->lock);
> +
> + return 0;
> +}
> +
> +static void nb6_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
> +{
> + struct nb6_data *data = to_nb6_pwm(chip);
> +
> + mutex_lock(&data->lock);
> + leds_pwm_update(data, pwm->hwpwm, 0);
> + mutex_unlock(&data->lock);
> +}
> +
> +static const struct pwm_ops nb6_pwm_ops = {
> + .request = nb6_pwm_request,
> + .free = nb6_pwm_free,
> + .config = nb6_pwm_config,
> + .enable = nb6_pwm_enable,
> + .disable = nb6_pwm_disable,
> + .owner = THIS_MODULE,
> +};
> +
> +/* Driver */
> +
> +static int nb6_hwmon_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct device *dev = &client->dev;
> + struct nb6_data *data;
> + struct device *hwmon_dev;
> + int ret;
> +
> + data = devm_kzalloc(dev, sizeof(struct nb6_data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + data->dev = dev;
> + data->i2c = client;
> + data->leds_mode = LEDS_MODE_NUM;
> + i2c_set_clientdata(client, data);
> + mutex_init(&data->lock);
> +
> + hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
> + data,
> + nb6_groups);
New drivers must use devm_hwmon_device_register_with_info().
> + if (IS_ERR(hwmon_dev))
> + return PTR_ERR(hwmon_dev);
> +
> + data->pwm.dev = dev;
> + data->pwm.ops = &nb6_pwm_ops;
> + data->pwm.base = -1;
> + data->pwm.npwm = NB6_LEDS_PWM_COUNT;
> +
> + ret = pwmchip_add(&data->pwm);
> + if (ret < 0)
> + return ret;
> +
This very much looks like a multi-function chip (hardware monitoring,
pwm, LEDs, and possibly watchdog) and should be implemented as such.
> + return 0;
> +};
> +
> +static const struct of_device_id nb6_hwmon_of_match[] = {
> + { .compatible = "sfr,nb6_hwmon" },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, nb6_hwmon_of_match);
> +
> +static struct i2c_driver nb6_hwmon_driver = {
> + .class = I2C_CLASS_HWMON,
> + .driver = {
> + .name = "nb6-hwmon",
> + .of_match_table = of_match_ptr(nb6_hwmon_of_match),
> + },
> + .probe = nb6_hwmon_probe,
> +};
> +module_i2c_driver(nb6_hwmon_driver);
>
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