Date:	Fri, 18 Jun 2010 18:53:48 +0100
From:	Jonathan Cameron <kernel@...23.retrosnub.co.uk>
To:	Guenter Roeck <guenter.roeck@...csson.com>
CC:	Jean Delvare <khali@...ux-fr.org>,
	Hans de Goede <hdegoede@...hat.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	lm-sensors@...sensors.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] hwmon: Driver for SMM665 Six-Channel Active DC Output
 Controller/Monitor


Hi,

I've taken a quick look through this code.

One or two specific comments below.

Only big question is why have the limit functionality in this driver?
Given the device has no hardware support and you don't have any form
of regular polling (I think) then these limits will only be noticed if
you query them. Hence why not leave this job to userspace?

I'm not saying you are wrong to do this. Just that you need to explain
your reasoning alongside the patch.


On 06/18/10 17:06, Guenter Roeck wrote:
> This driver adds support for the monitoring features of the Summit
> Microelectronics SMM665 Six-Channel Active DC Output Controller/Monitor.
> 
> Signed-off-by: Guenter Roeck <guenter.roeck@...csson.com>
> ---
>  drivers/hwmon/Kconfig  |   12 +
>  drivers/hwmon/Makefile |    1 +
>  drivers/hwmon/smm665.c |  739 ++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 752 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/hwmon/smm665.c
> 
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index e19cf8e..fc5e229 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -739,6 +739,18 @@ config SENSORS_SIS5595
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called sis5595.
>  
> +config SENSORS_SMM665
> +	tristate "Summit Microelectronics SMM665"
> +	depends on I2C && EXPERIMENTAL
> +	default n
> +	help
> +	  If you say yes here you get support for the hardware monitoring
> +	  features of the Summit Microelectronics SMM665 Six-Channel
> +	  Active DC Output Controller / Monitor.
> +
> +	  This driver can also be built as a module. If so, the module will
> +	  be called smm665.
> +
>  config SENSORS_DME1737
>  	tristate "SMSC DME1737, SCH311x and compatibles"
>  	depends on I2C && EXPERIMENTAL
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 2138ceb..8a5c9f5 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_SENSORS_LM93)	+= lm93.o
>  obj-$(CONFIG_SENSORS_LM95241)	+= lm95241.o
>  obj-$(CONFIG_SENSORS_LTC4215)	+= ltc4215.o
>  obj-$(CONFIG_SENSORS_LTC4245)	+= ltc4245.o
> +obj-$(CONFIG_SENSORS_SMM665)	+= smm665.o
>  obj-$(CONFIG_SENSORS_MAX1111)	+= max1111.o
>  obj-$(CONFIG_SENSORS_MAX1619)	+= max1619.o
>  obj-$(CONFIG_SENSORS_MAX6650)	+= max6650.o
> diff --git a/drivers/hwmon/smm665.c b/drivers/hwmon/smm665.c
> new file mode 100644
> index 0000000..84d9d21
> --- /dev/null
> +++ b/drivers/hwmon/smm665.c
> @@ -0,0 +1,739 @@
> +/*
> + * Driver for SMM665 Power Controller / Monitor
> + *
> + * Copyright (C) 2010 Ericsson AB.
> + *
> + * 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 should with no or minor modifications also work for SMM766,
> + * SMM764, and SMM465. Only monitoring functionality is implemented.
> + *
> + * Datasheets:
> + * http://www.summitmicro.com/prod_select/summary/SMM665/SMM665B_2089_20.pdf
> + * http://www.summitmicro.com/prod_select/summary/SMM766B/SMM766B_2122.pdf
> + */
> +
> +#include <linux/kernel.h>
> +#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>
> +#include <linux/delay.h>
> +

Personally I'd be more inclined to do these as a whole lot
of '#define's.  You never use the enum type for anything
so why bother?

> +/* ADC channel addresses */
> +enum smm665_adcregs {
> +	SMM665_MISC16_ADC_DATA_A = 0x00,
> +	SMM665_MISC16_ADC_DATA_B = 0x01,
> +	SMM665_MISC16_ADC_DATA_C = 0x02,
> +	SMM665_MISC16_ADC_DATA_D = 0x03,
> +	SMM665_MISC16_ADC_DATA_E = 0x04,
> +	SMM665_MISC16_ADC_DATA_F = 0x05,
> +	SMM665_MISC16_ADC_DATA_VDD = 0x06,
> +	SMM665_MISC16_ADC_DATA_12V = 0x07,
> +	SMM665_MISC16_ADC_DATA_INT_TEMP = 0x08,
> +	SMM665_MISC16_ADC_DATA_AIN1 = 0x09,
> +	SMM665_MISC16_ADC_DATA_AIN2 = 0x0a,
> +};
> +
> +enum smm665_cmdregs {
> +	SMM665_MISC8_CMD_STS = 0x80,
> +	SMM665_MISC8_STATUS1 = 0x81,
> +	SMM665_MISC8_STATUSS2 = 0x82,
> +	SMM665_MISC8_IO_POLARITY = 0x83,
> +	SMM665_MISC8_PUP_POLARITY = 0x84,
> +	SMM665_MISC8_ADOC_STATUS1 = 0x85,
> +	SMM665_MISC8_ADOC_STATUS2 = 0x86,
> +	SMM665_MISC8_WRITE_PROT = 0x87,
> +	SMM665_MISC8_STS_TRACK = 0x88,
> +};
> +
> +/*
> + * Configuration registers and register groups
> + */
> +#define SMM665_ADOC_ENABLE		0x0d
> +#define SMM665_LIMIT_BASE		0x80
> +
> +/*
> + * Limit register bit masks
> + */
> +#define SMM665_TRIGGER_RST	0x8000
> +#define SMM665_TRIGGER_HEALTHY	0x4000
> +#define SMM665_TRIGGER_POWEROFF	0x2000
> +#define SMM665_TRIGGER_SHUTDOWN	0x1000
> +#define SMM665_ADC_MASK		0x03ff
> +
> +#define smm665_is_critical(lim)	((lim) & (SMM665_TRIGGER_RST \
> +					| SMM665_TRIGGER_POWEROFF \
> +					| SMM665_TRIGGER_SHUTDOWN))
> +/*
> + * Fault register bit definitions
> + * Values are merged from status registers 1/2,
> + * with status register 1 providing the upper 8 bits.
> + */
> +#define SMM665_FAULT_A		0x0001
> +#define SMM665_FAULT_B		0x0002
> +#define SMM665_FAULT_C		0x0004
> +#define SMM665_FAULT_D		0x0008
> +#define SMM665_FAULT_E		0x0010
> +#define SMM665_FAULT_F		0x0020
> +#define SMM665_FAULT_VDD	0x0040
> +#define SMM665_FAULT_12V	0x0080
> +#define SMM665_FAULT_TEMP	0x0100
> +#define SMM665_FAULT_AIN1	0x0200
> +#define SMM665_FAULT_AIN2	0x0400
> +
> +/*
> + * I2C Register addresses
> + *
> + * The configuration register needs to be the configured base register.
> + * The command/status register address is derived from it.
> + */
> +#define SMM665_REGMASK		0x78
> +#define SMM665_CMDREG_BASE	0x48
> +#define SMM665_CONFREG_BASE	0x50
> +
> +/* Internal reference voltage (VREF, x 1000 */
> +#define SMM665_VREF_ADC_X1000	1250
> +
> +/*
> + *  Equations given by chip manufacturer to calculate voltage/temperature values
> + *  vref = Reference voltage on VREF_ADC pin
> + *  adc  = 10bit ADC value read back from registers
> + */
> +
I guess these are handy if you ever intend to allow different reference voltages,
but right now they add code and reduce readability.  Obviously leave be if the
intent is add that vref control in a later patch!
> +/* Voltage A-F and VDD */
> +#define SMM665_VMON_ADC_TO_VOLTS(vref, adc)  ((adc) * (vref) / 256)
> +
> +/* Voltage 12VIN */
> +#define SMM665_12VIN_ADC_TO_VOLTS(vref, adc) ((adc) * (vref) * 3 / 256)
> +
> +/* Voltage AIN1, AIN2 */
> +#define SMM665_AIN_ADC_TO_VOLTS(vref, adc)   ((adc) * (vref) / 512)
> +
> +/* Temp Sensor */
> +#define SMM665_TEMP_ADC_TO_CELSIUS(adc)      ((adc) <= 511) ?		   \
> +					      ((int)(adc) * 1000 / 4) :	   \
> +					      (((int)(adc) - 0x400) * 1000 / 4)
> +
> +#define SMM665_NUM_ADC		11
> +#define SMM665_ADC_RETRIES	5
> +#define SMM665_ADC_WAIT		100	/* conversion time is 70 uS for SMM665B,
> +					   182 uS for SMM766 */
> +
> +struct smm665_data {
> +	struct device *hwmon_dev;
> +
> +	struct mutex update_lock;
> +	bool valid;
> +	unsigned long last_updated;	/* in jiffies */
> +	u16 adc[SMM665_NUM_ADC];	/* adc values (raw) */
> +	u16 faults;			/* fault status */

Given these aren't used often, I'd prefer more meaningful variable names.
> +	int cu[SMM665_NUM_ADC];		/* critical under limit (converted) */
> +	int au[SMM665_NUM_ADC];		/* alarm under limit (converted) */
> +	int co[SMM665_NUM_ADC];		/* critical over limit (converted) */
> +	int ao[SMM665_NUM_ADC];		/* alarm over limit (converted) */
> +	struct i2c_client *cmdreg;
> +};
> +
> +/*
> + * smm665_read16()
> + *
> + * Read 16 bit value from <reg>, <reg+1>. Upper 8 bits are in <reg>.
> + */
> +static int smm665_read16(struct i2c_client *client, int reg)
> +{
> +	int rv, val;
> +
> +	rv = i2c_smbus_read_byte_data(client, reg);
> +	if (rv < 0)
> +		return rv;
> +	val = rv << 8;
> +	rv = i2c_smbus_read_byte_data(client, reg + 1);
> +	if (rv < 0)
> +		return rv;
> +	val |= rv;
> +	return val;
> +}
> +
> +/*
> + * Read adc value.
> + */
> +static int smm665_read_adc(struct i2c_client *client, int adc)
> +{
> +	int rv = -1;
> +	int retries;
> +
Why the retries?  If there is a reason for this to sometimes fail, please
add a comment explaining what it is! If it is a hardware bug, then tell us!
> +	for (retries = 0; retries < SMM665_ADC_RETRIES; retries++) {
> +		int radc;
> +
> +		/*
> +		 * Algorithm for reading ADC, per SMM665 datasheet
> +		 *
> +		 *  {[S][addr][W][Ack]} {[offset][Ack]} {[S][addr][R][Nack]}
> +		 * [wait 70 uS]
> +		 *  {[S][addr][R][Ack]} {[datahi][Ack]} {[datalo][Ack][P]}
> +		 *
> +		 * To implement the first part of this exchange,
> +		 * do a full read transaction and expect a failure/Nack.
> +		 * This sets up the address pointer on the SMM665
> +		 * and starts the ADC conversion.
> +		 * Then do a two-byte read transaction.
> +		 */
Is there no better way of handling this? There are protocol mangling hacks
to tell the i2c core to ignore a NAKs under some circumstances.

> +		rv = i2c_smbus_read_byte_data(client, adc << 3);
> +		if (rv >= 0) {
> +			/* No error, something is wrong. Retry. */
> +			rv = -1;
> +			continue;
> +		}
> +		udelay(SMM665_ADC_WAIT);
> +		/*
> +		 * Now read two bytes.
> +		 *
> +		 * Neither i2c_smbus_read_byte() nor
> +		 * i2c_smbus_read_block_data() worked here,
> +		 * so use i2c_smbus_read_word_data() instead.
> +		 * We could also try to use i2c_master_recv(),
> +		 * but that is not always supported.
> +		 */
> +		rv = i2c_smbus_read_word_data(client, 0);
> +		if (rv < 0)
> +			continue;
> +		/*
> +		 * Validate/verify readback adc channel (in bit 11..14)
> +		 * High byte is in lower 8 bit of rv, so only shift by 3.
> +		 */
> +		radc = (rv >> 3) & 0x0f;
> +		if (radc != adc) {
> +			rv = -1;
> +			continue;
> +		}
> +
> +		/* Byte order is reversed, need to swap. */
Isn't this endian dependent?
> +		rv = swab16(rv) & SMM665_ADC_MASK;
> +		break;
> +	}
> +	return rv;
> +}
> +
> +static struct smm665_data *smm665_update_device(struct device *dev)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct smm665_data *data = i2c_get_clientdata(client);
> +
> +	mutex_lock(&data->update_lock);
> +
> +	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
> +		int i, faults;
> +
> +		/*
> +		 * read status registers
> +		 */
> +		faults = smm665_read16(client, SMM665_MISC8_STATUS1);
> +		if (unlikely(faults < 0))
> +			data->faults = 0;
> +		else
> +			data->faults = faults;
> +
> +		/* Read adc registers */
> +		for (i = 0; i < SMM665_NUM_ADC; i++) {
> +			int val = smm665_read_adc(data->cmdreg, i);
> +			if (unlikely(val < 0))
> +				data->adc[i] = 0;
> +			else
> +				data->adc[i] = val;
> +		}
> +
> +		data->last_updated = jiffies;
> +		data->valid = 1;
> +	}
> +
> +	mutex_unlock(&data->update_lock);
> +
> +	return data;
> +}
> +
> +/* Return converted value from given adc */
> +static int smm665_convert(u16 adcval, int index)
> +{
> +	int val = 0;
> +
> +	switch (index) {
> +	case SMM665_MISC16_ADC_DATA_12V:
> +		val = SMM665_12VIN_ADC_TO_VOLTS(SMM665_VREF_ADC_X1000,
> +						adcval & SMM665_ADC_MASK);
> +		break;
> +
> +	case SMM665_MISC16_ADC_DATA_VDD:
> +	case SMM665_MISC16_ADC_DATA_A:
> +	case SMM665_MISC16_ADC_DATA_B:
> +	case SMM665_MISC16_ADC_DATA_C:
> +	case SMM665_MISC16_ADC_DATA_D:
> +	case SMM665_MISC16_ADC_DATA_E:
> +	case SMM665_MISC16_ADC_DATA_F:
> +		val = SMM665_VMON_ADC_TO_VOLTS(SMM665_VREF_ADC_X1000,
> +					       adcval & SMM665_ADC_MASK);
> +		break;
> +
> +	case SMM665_MISC16_ADC_DATA_AIN1:
> +	case SMM665_MISC16_ADC_DATA_AIN2:
> +		val = SMM665_AIN_ADC_TO_VOLTS(SMM665_VREF_ADC_X1000,
> +					      adcval & SMM665_ADC_MASK);
> +		break;
> +
> +	case SMM665_MISC16_ADC_DATA_INT_TEMP:
> +		val = SMM665_TEMP_ADC_TO_CELSIUS(adcval & SMM665_ADC_MASK);
> +		break;
> +
> +	default:
> +		/* If we get here, the developer messed up */
> +		WARN_ON_ONCE(1);
> +		break;
> +	}
> +
> +	return val;
> +}
> +
> +/* Return converted value from given adc */
> +static int smm665_get_input(struct device *dev, int adc)
> +{
> +	struct smm665_data *data = smm665_update_device(dev);
> +
> +	return smm665_convert(data->adc[adc], adc);
> +}
> +
> +static int smm665_get_min(struct device *dev, int index)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct smm665_data *data = i2c_get_clientdata(client);
> +
> +	return data->au[index];
> +}
> +
> +static int smm665_get_max(struct device *dev, int index)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct smm665_data *data = i2c_get_clientdata(client);
> +
> +	return data->ao[index];
> +}
> +
> +static int smm665_get_crit(struct device *dev, int index)
> +{
> +	struct i2c_client *client = to_i2c_client(dev);
> +	struct smm665_data *data = i2c_get_clientdata(client);
> +
> +	return data->co[index];
> +}
> +

I'm confused.  So these alarms are purely software constructs.
Given I don't think the device does regular polling, why not
leave this to userspace?

> +static int smm665_get_min_alarm(struct device *dev, int index)
> +{
> +	struct smm665_data *data = smm665_update_device(dev);
> +	int val = smm665_convert(data->adc[index], index);
> +
> +	/*
> +	 * Look for lower alarm limit. Report alarm if the current
> +	 * adc value is equal to or lower than the specified limit.
> +	 */
> +	if (val <= data->au[index])
> +		return 1;
(nitpick) Inconsistent spacing between this and the next function.
> +	return 0;
> +}
> +
> +static int smm665_get_max_alarm(struct device *dev, int index)
> +{
> +	struct smm665_data *data = smm665_update_device(dev);
> +	int val = smm665_convert(data->adc[index], index);
> +
> +	/*
> +	 * Look for upper alarm limit. Report alarm if the current
> +	 * adc value is equal to or larger than the specified limit.
> +	 */
> +	if (val >= data->ao[index])
> +		return 1;
> +
> +	return 0;
> +}
> +
> +static int smm665_get_fault(struct device *dev, int index)
> +{
> +	struct smm665_data *data = smm665_update_device(dev);
> +
> +	if (data->faults & (1 << index))
> +		return 1;
> +
> +	return 0;
> +}
> +
> +#define SMM665_SHOW(what) \
> +  static ssize_t smm665_show_##what(struct device *dev, \
> +				    struct device_attribute *da, char *buf) \
> +{ \
> +	struct sensor_device_attribute *attr = to_sensor_dev_attr(da); \
> +	const int val = smm665_get_##what(dev, attr->index); \
> +	return snprintf(buf, PAGE_SIZE, "%d\n", val); \
> +}
> +
> +SMM665_SHOW(input);
> +SMM665_SHOW(min);
> +SMM665_SHOW(max);
> +SMM665_SHOW(crit);
> +SMM665_SHOW(fault);
> +SMM665_SHOW(min_alarm);
> +SMM665_SHOW(max_alarm);
> +
> +/* 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 SMM665_ATTR(name, type, cmd_idx) \
> +	static SENSOR_DEVICE_ATTR(name##_##type, S_IRUGO, \
> +				  smm665_show_##type, NULL, cmd_idx)
> +
> +/* Construct a sensor_device_attribute structure for each register */
> +
> +/* Input voltages */
> +SMM665_ATTR(in1, input, SMM665_MISC16_ADC_DATA_12V);
> +SMM665_ATTR(in2, input, SMM665_MISC16_ADC_DATA_VDD);
> +SMM665_ATTR(in3, input, SMM665_MISC16_ADC_DATA_A);
> +SMM665_ATTR(in4, input, SMM665_MISC16_ADC_DATA_B);
> +SMM665_ATTR(in5, input, SMM665_MISC16_ADC_DATA_C);
> +SMM665_ATTR(in6, input, SMM665_MISC16_ADC_DATA_D);
> +SMM665_ATTR(in7, input, SMM665_MISC16_ADC_DATA_E);
> +SMM665_ATTR(in8, input, SMM665_MISC16_ADC_DATA_F);
> +SMM665_ATTR(in9, input, SMM665_MISC16_ADC_DATA_AIN1);
> +SMM665_ATTR(in10, input, SMM665_MISC16_ADC_DATA_AIN2);
> +
> +/* Input voltages min */
> +SMM665_ATTR(in1, min, SMM665_MISC16_ADC_DATA_12V);
> +SMM665_ATTR(in2, min, SMM665_MISC16_ADC_DATA_VDD);
> +SMM665_ATTR(in3, min, SMM665_MISC16_ADC_DATA_A);
> +SMM665_ATTR(in4, min, SMM665_MISC16_ADC_DATA_B);
> +SMM665_ATTR(in5, min, SMM665_MISC16_ADC_DATA_C);
> +SMM665_ATTR(in6, min, SMM665_MISC16_ADC_DATA_D);
> +SMM665_ATTR(in7, min, SMM665_MISC16_ADC_DATA_E);
> +SMM665_ATTR(in8, min, SMM665_MISC16_ADC_DATA_F);
> +SMM665_ATTR(in9, min, SMM665_MISC16_ADC_DATA_AIN1);
> +SMM665_ATTR(in10, min, SMM665_MISC16_ADC_DATA_AIN2);
> +
> +/* Input voltages max */
> +SMM665_ATTR(in1, max, SMM665_MISC16_ADC_DATA_12V);
> +SMM665_ATTR(in2, max, SMM665_MISC16_ADC_DATA_VDD);
> +SMM665_ATTR(in3, max, SMM665_MISC16_ADC_DATA_A);
> +SMM665_ATTR(in4, max, SMM665_MISC16_ADC_DATA_B);
> +SMM665_ATTR(in5, max, SMM665_MISC16_ADC_DATA_C);
> +SMM665_ATTR(in6, max, SMM665_MISC16_ADC_DATA_D);
> +SMM665_ATTR(in7, max, SMM665_MISC16_ADC_DATA_E);
> +SMM665_ATTR(in8, max, SMM665_MISC16_ADC_DATA_F);
> +SMM665_ATTR(in9, max, SMM665_MISC16_ADC_DATA_AIN1);
> +SMM665_ATTR(in10, max, SMM665_MISC16_ADC_DATA_AIN2);
> +
> +/* Input voltage min alarms */
> +SMM665_ATTR(in1, min_alarm, SMM665_MISC16_ADC_DATA_12V);
> +SMM665_ATTR(in2, min_alarm, SMM665_MISC16_ADC_DATA_VDD);
> +SMM665_ATTR(in3, min_alarm, SMM665_MISC16_ADC_DATA_A);
> +SMM665_ATTR(in4, min_alarm, SMM665_MISC16_ADC_DATA_B);
> +SMM665_ATTR(in5, min_alarm, SMM665_MISC16_ADC_DATA_C);
> +SMM665_ATTR(in6, min_alarm, SMM665_MISC16_ADC_DATA_D);
> +SMM665_ATTR(in7, min_alarm, SMM665_MISC16_ADC_DATA_E);
> +SMM665_ATTR(in8, min_alarm, SMM665_MISC16_ADC_DATA_F);
> +SMM665_ATTR(in9, min_alarm, SMM665_MISC16_ADC_DATA_AIN1);
> +SMM665_ATTR(in10, min_alarm, SMM665_MISC16_ADC_DATA_AIN2);
> +
> +/* Input voltage max alarms */
> +SMM665_ATTR(in1, max_alarm, SMM665_MISC16_ADC_DATA_12V);
> +SMM665_ATTR(in2, max_alarm, SMM665_MISC16_ADC_DATA_VDD);
> +SMM665_ATTR(in3, max_alarm, SMM665_MISC16_ADC_DATA_A);
> +SMM665_ATTR(in4, max_alarm, SMM665_MISC16_ADC_DATA_B);
> +SMM665_ATTR(in5, max_alarm, SMM665_MISC16_ADC_DATA_C);
> +SMM665_ATTR(in6, max_alarm, SMM665_MISC16_ADC_DATA_D);
> +SMM665_ATTR(in7, max_alarm, SMM665_MISC16_ADC_DATA_E);
> +SMM665_ATTR(in8, max_alarm, SMM665_MISC16_ADC_DATA_F);
> +SMM665_ATTR(in9, max_alarm, SMM665_MISC16_ADC_DATA_AIN1);
> +SMM665_ATTR(in10, max_alarm, SMM665_MISC16_ADC_DATA_AIN2);
> +
> +/* Faults */
> +SMM665_ATTR(in1, fault, SMM665_FAULT_12V);
> +SMM665_ATTR(in2, fault, SMM665_FAULT_VDD);
> +SMM665_ATTR(in3, fault, SMM665_FAULT_A);
> +SMM665_ATTR(in4, fault, SMM665_FAULT_B);
> +SMM665_ATTR(in5, fault, SMM665_FAULT_C);
> +SMM665_ATTR(in6, fault, SMM665_FAULT_D);
> +SMM665_ATTR(in7, fault, SMM665_FAULT_E);
> +SMM665_ATTR(in8, fault, SMM665_FAULT_F);
> +SMM665_ATTR(in9, fault, SMM665_FAULT_AIN1);
> +SMM665_ATTR(in10, fault, SMM665_FAULT_AIN2);
> +
> +/* Temperature */
> +SMM665_ATTR(temp1, input, SMM665_MISC16_ADC_DATA_INT_TEMP);
> +SMM665_ATTR(temp1, min, SMM665_MISC16_ADC_DATA_INT_TEMP);
> +SMM665_ATTR(temp1, max, SMM665_MISC16_ADC_DATA_INT_TEMP);
> +SMM665_ATTR(temp1, crit, SMM665_MISC16_ADC_DATA_INT_TEMP);
> +SMM665_ATTR(temp1, min_alarm, SMM665_MISC16_ADC_DATA_INT_TEMP);
> +SMM665_ATTR(temp1, max_alarm, SMM665_MISC16_ADC_DATA_INT_TEMP);
> +SMM665_ATTR(temp1, fault, SMM665_FAULT_TEMP);
> +
> +/*
> + * Finally, construct an array of pointers to members of the above objects,
> + * as required for sysfs_create_group()
> + */
> +static struct attribute *smm665_attributes[] = {
> +	&sensor_dev_attr_in1_input.dev_attr.attr,
> +	&sensor_dev_attr_in1_min.dev_attr.attr,
> +	&sensor_dev_attr_in1_max.dev_attr.attr,
> +	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in1_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in2_input.dev_attr.attr,
> +	&sensor_dev_attr_in2_min.dev_attr.attr,
> +	&sensor_dev_attr_in2_max.dev_attr.attr,
> +	&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in2_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in2_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in3_input.dev_attr.attr,
> +	&sensor_dev_attr_in3_min.dev_attr.attr,
> +	&sensor_dev_attr_in3_max.dev_attr.attr,
> +	&sensor_dev_attr_in3_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in3_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in3_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in4_input.dev_attr.attr,
> +	&sensor_dev_attr_in4_min.dev_attr.attr,
> +	&sensor_dev_attr_in4_max.dev_attr.attr,
> +	&sensor_dev_attr_in4_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in4_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in4_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in5_input.dev_attr.attr,
> +	&sensor_dev_attr_in5_min.dev_attr.attr,
> +	&sensor_dev_attr_in5_max.dev_attr.attr,
> +	&sensor_dev_attr_in5_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in5_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in5_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in6_input.dev_attr.attr,
> +	&sensor_dev_attr_in6_min.dev_attr.attr,
> +	&sensor_dev_attr_in6_max.dev_attr.attr,
> +	&sensor_dev_attr_in6_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in6_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in6_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in7_input.dev_attr.attr,
> +	&sensor_dev_attr_in7_min.dev_attr.attr,
> +	&sensor_dev_attr_in7_max.dev_attr.attr,
> +	&sensor_dev_attr_in7_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in7_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in7_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in8_input.dev_attr.attr,
> +	&sensor_dev_attr_in8_min.dev_attr.attr,
> +	&sensor_dev_attr_in8_max.dev_attr.attr,
> +	&sensor_dev_attr_in8_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in8_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in8_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in9_input.dev_attr.attr,
> +	&sensor_dev_attr_in9_min.dev_attr.attr,
> +	&sensor_dev_attr_in9_max.dev_attr.attr,
> +	&sensor_dev_attr_in9_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in9_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in9_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_in10_input.dev_attr.attr,
> +	&sensor_dev_attr_in10_min.dev_attr.attr,
> +	&sensor_dev_attr_in10_max.dev_attr.attr,
> +	&sensor_dev_attr_in10_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in10_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_in10_fault.dev_attr.attr,
> +
> +	&sensor_dev_attr_temp1_input.dev_attr.attr,
> +	&sensor_dev_attr_temp1_min.dev_attr.attr,
> +	&sensor_dev_attr_temp1_max.dev_attr.attr,
> +	&sensor_dev_attr_temp1_crit.dev_attr.attr,
> +	&sensor_dev_attr_temp1_min_alarm.dev_attr.attr,
> +	&sensor_dev_attr_temp1_max_alarm.dev_attr.attr,
> +	&sensor_dev_attr_temp1_fault.dev_attr.attr,
> +
> +	NULL,
> +};
> +
> +static const struct attribute_group smm665_group = {
> +	.attrs = smm665_attributes,
> +};
> +
> +static int smm665_probe(struct i2c_client *client,
> +			const struct i2c_device_id *id)
> +{
> +	struct i2c_adapter *adapter = client->adapter;
> +	struct smm665_data *data;
> +	int i, ret;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA
> +				     | I2C_FUNC_SMBUS_WORD_DATA))
> +		return -ENODEV;
> +
> +	if (i2c_smbus_read_byte_data(client, SMM665_ADOC_ENABLE) < 0)
> +		return -ENODEV;
> +
> +	data = kzalloc(sizeof(*data), GFP_KERNEL);
> +	if (!data) {
> +		ret = -ENOMEM;
> +		goto out_kzalloc;
> +	}
> +
> +	i2c_set_clientdata(client, data);
> +	mutex_init(&data->update_lock);
> +
> +	data->cmdreg = i2c_new_dummy(adapter, (client->addr & ~SMM665_REGMASK)
> +				     | SMM665_CMDREG_BASE);
> +	if (!data->cmdreg) {
> +		ret = -ENOMEM;
> +		goto out_new_dummy;
> +	}
> +	if (i2c_smbus_read_byte_data(data->cmdreg, SMM665_MISC8_CMD_STS) < 0) {
> +		ret = -ENODEV;
> +		goto out_sysfs_create_group;
> +	}
> +
> +	/*
> +	 * Read limits.
> +	 *
> +	 * Limit registers start with register SMM665_LIMIT_BASE.
> +	 * Each channel uses 8 registers, providing four limit values
> +	 * per channel.
> +	 *
> +	 * Available limits from chip registers, per channel:
A simple statement of endianess and number of bytes would do the job.
> +	 *  u1: under limit 1
> +	 *  u2: under limit 2
> +	 *  o1: over limit 1
> +	 *  o2: over limit 2
> +	 *
> +	 * Register address offsets:
> +	 * +0:  u1[h]
> +	 * +1:  u1[l]
> +	 * +2:  u2[h]
> +	 * +3:  u2[l]
> +	 * +4:  o1[h]
> +	 * +5:  o1[l]
> +	 * +6:  o2[h]
> +	 * +7:  o2[l]
> +	 *
> +	 * Limit register order is as defined with smm665_adcregs,
> +	 * so we use smm665_adcregs values throughout the code to index
> +	 * limit registers.
> +	 *
> +	 * We save the first retrieved value both as "critical" and "alarm"
> +	 * value. The second value overwrites either the critical or the
> +	 * alarm value, depending on its configuration. This ensures that both
> +	 * critical and alarm values are initialized, even if both registers are
> +	 * configured as critical or non-critical.
> +	 *
> +	 * Note: Critical values for voltage channels are saved, even though
> +	 * this information is currently not used by the driver. This is mostly
> +	 * for consistency, though it might eventually be useful if future APIs
> +	 * support reporting "critical" voltage values.
> +	 */
> +	ret = -ENODEV;
> +	for (i = 0; i < SMM665_NUM_ADC; i++) {
> +		int val;
> +
> +		val = smm665_read16(client, SMM665_LIMIT_BASE + i * 8);
> +		if (unlikely(val < 0))
> +			goto out_sysfs_create_group;
> +		data->cu[i] = data->au[i] = smm665_convert(val, i);
> +		val = smm665_read16(client, SMM665_LIMIT_BASE + i * 8 + 2);
> +		if (unlikely(val < 0))
> +			goto out_sysfs_create_group;
> +		if (smm665_is_critical(val))
> +			data->cu[i] = smm665_convert(val, i);
> +		else
> +			data->au[i] = smm665_convert(val, i);
> +		val = smm665_read16(client, SMM665_LIMIT_BASE + i * 8 + 4);
> +		if (unlikely(val < 0))
> +			goto out_sysfs_create_group;
> +		data->co[i] = data->ao[i] = smm665_convert(val, i);
> +		val = smm665_read16(client, SMM665_LIMIT_BASE + i * 8 + 6);
> +		if (unlikely(val < 0))
> +			goto out_sysfs_create_group;
> +		if (smm665_is_critical(val))
> +			data->co[i] = smm665_convert(val, i);
> +		else
> +			data->ao[i] = smm665_convert(val, i);
> +	}
> +
> +	/* Register sysfs hooks */
> +	ret = sysfs_create_group(&client->dev.kobj, &smm665_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, &smm665_group);
> +out_sysfs_create_group:
> +	i2c_unregister_device(data->cmdreg);
> +out_new_dummy:
> +	kfree(data);
> +out_kzalloc:
> +	return ret;
> +}
> +
> +static int smm665_remove(struct i2c_client *client)
> +{
> +	struct smm665_data *data = i2c_get_clientdata(client);
> +
> +	i2c_unregister_device(data->cmdreg);
> +	hwmon_device_unregister(data->hwmon_dev);
> +	sysfs_remove_group(&client->dev.kobj, &smm665_group);
> +
> +	kfree(data);
> +
> +	return 0;
> +}
> +

Personally I'd be cynical.  If the other devices you list above
should work. I'd add them to the id table and Kconfig description
and just put a note saying they are untested.

Obviously don't do this if you have any reason to suspect they
are not fully compatible.

But then that is me :)

> +static const struct i2c_device_id smm665_id[] = {
> +	{"smm665", 0},
> +	{}
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, smm665_id);
> +
> +/* This is the driver that will be inserted */
> +static struct i2c_driver smm665_driver = {
> +	.driver = {
> +		   .name = "smm665",
> +		   },
> +	.probe = smm665_probe,
> +	.remove = smm665_remove,
> +	.id_table = smm665_id,
> +};
> +
> +static int __init smm665_init(void)
> +{
> +	return i2c_add_driver(&smm665_driver);
> +}
> +
> +static void __exit smm665_exit(void)
> +{
> +	i2c_del_driver(&smm665_driver);
> +}
> +
> +MODULE_AUTHOR("Guenter Roeck");
> +MODULE_DESCRIPTION("SMM665 driver");
> +MODULE_LICENSE("GPL");
> +
> +module_init(smm665_init);
> +module_exit(smm665_exit);

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