Re: [PATCH] ds2782_battery: add support for ds2786 battery gas gauge

From: Ryan Mallon
Date: Thu Apr 22 2010 - 17:24:59 EST

Mike Rapoport wrote:
> From: Yulia Vilensky <vilensky@xxxxxxxxxxxxxx>

Thanks for this, some comments below.

> Signed-off-by: Yulia Vilensky <vilensky@xxxxxxxxxxxxxx>
> Signed-off-by: Mike Rapoport <mike@xxxxxxxxxxxxxx>
> ---
> drivers/power/Kconfig | 4 +-
> drivers/power/ds2782_battery.c | 217 +++++++++++++++++++++++++++++++--------
> include/linux/ds2782_battery.h | 8 ++
> 3 files changed, 182 insertions(+), 47 deletions(-)
> create mode 100644 include/linux/ds2782_battery.h
>
> diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
> index faaa9b4..d8b8a19 100644
> --- a/drivers/power/Kconfig
> +++ b/drivers/power/Kconfig
> @@ -65,10 +65,10 @@ config BATTERY_DS2760
> Say Y here to enable support for batteries with ds2760 chip.
>
> config BATTERY_DS2782
> - tristate "DS2782 standalone gas-gauge"
> + tristate "DS2782/DS2786 standalone gas-gauge"
> depends on I2C
> help
> - Say Y here to enable support for the DS2782 standalone battery
> + Say Y here to enable support for the DS2782/DS2786 standalone battery

I have only used the DS2782 chip. Can we just change this to DS278x? May
as well change to CONFIG_BATTERY_DS278x while we are here.

> gas-gauge.
>
> config BATTERY_PMU
> diff --git a/drivers/power/ds2782_battery.c b/drivers/power/ds2782_battery.c
> index 99c8997..0df49b4 100644
> --- a/drivers/power/ds2782_battery.c
> +++ b/drivers/power/ds2782_battery.c
> @@ -5,6 +5,8 @@
> *
> * Author: Ryan Mallon <ryan@xxxxxxxxxxxxxxxx>
> *
> + * DS278 added by Yulia Vilensky <vilensky@xxxxxxxxxxxxxx>
> + *
> * This program is free software; you can redistribute it and/or modify
> * it under the terms of the GNU General Public License version 2 as
> * published by the Free Software Foundation.
> @@ -20,6 +22,7 @@
> #include <linux/idr.h>
> #include <linux/power_supply.h>
> #include <linux/slab.h>
> +#include <linux/ds2782_battery.h>
>
> #define DS2782_REG_RARC 0x06 /* Remaining active relative capacity */
>
> @@ -33,18 +36,39 @@
> /* Current unit measurement in uA for a 1 milli-ohm sense resistor */
> #define DS2782_CURRENT_UNITS 1563
>
> -#define to_ds2782_info(x) container_of(x, struct ds2782_info, battery)
> +#define DS2786_REG_RARC 0x02 /* Remaining active relative capacity */
> +
> +#define DS2786_REG_VOLT_MSB 0x0c
> +#define DS2786_REG_TEMP_MSB 0x0a
> +#define DS2786_REG_CURRENT_MSB 0x0e

#define DS278x_REG_CURRENT_MSB 0x0e

Its the same register on both chips, no need for two #defines. Same of
the other registers, except for RARC.

> +
> +#define DS2786_CURRENT_UNITS 25

If we make this a member of the info structure, we can easily use it in
calculations for both chips, ie

current_uA = raw * (info->current_units / sense_res);

> +#define DS278X_SIGN_BIT_MASK16 0x8000
> +
> +struct ds278x_info;
>
> -struct ds2782_info {
> +struct ds278x_battery_ops {
> + int (*get_temp)(struct ds278x_info *info, int *temp);
> + int (*get_current)(struct ds278x_info *info, int *current_uA);
> + int (*get_voltage)(struct ds278x_info *info, int *voltage_uA);
> + int (*get_capacity)(struct ds278x_info *info, int *capacity_uA);
> +};
> +
> +#define to_ds278x_info(x) container_of(x, struct ds278x_info, battery)
> +
> +struct ds278x_info {
> struct i2c_client *client;
> struct power_supply battery;
> + struct ds278x_battery_ops *ops;
> int id;
> + int rsns;
> };
>
> static DEFINE_IDR(battery_id);
> static DEFINE_MUTEX(battery_lock);
>
> -static inline int ds2782_read_reg(struct ds2782_info *info, int reg, u8 *val)
> +static inline int ds278x_read_reg(struct ds278x_info *info, int reg, u8 *val)
> {
> int ret;
>
> @@ -58,7 +82,7 @@ static inline int ds2782_read_reg(struct ds2782_info *info, int reg, u8 *val)
> return 0;
> }
>
> -static inline int ds2782_read_reg16(struct ds2782_info *info, int reg_msb,
> +static inline int ds278x_read_reg16(struct ds278x_info *info, int reg_msb,
> s16 *val)
> {
> int ret;
> @@ -73,7 +97,7 @@ static inline int ds2782_read_reg16(struct ds2782_info *info, int reg_msb,
> return 0;
> }
>
> -static int ds2782_get_temp(struct ds2782_info *info, int *temp)
> +static int ds2782_get_temp(struct ds278x_info *info, int *temp)
> {
> s16 raw;
> int err;
> @@ -84,14 +108,14 @@ static int ds2782_get_temp(struct ds2782_info *info, int *temp)
> * celsius. The temperature value is stored as a 10 bit number, plus
> * sign in the upper bits of a 16 bit register.
> */
> - err = ds2782_read_reg16(info, DS2782_REG_TEMP_MSB, &raw);
> + err = ds278x_read_reg16(info, DS2782_REG_TEMP_MSB, &raw);
> if (err)
> return err;
> *temp = ((raw / 32) * 125) / 100;
> return 0;
> }
>
> -static int ds2782_get_current(struct ds2782_info *info, int *current_uA)
> +static int ds2782_get_current(struct ds278x_info *info, int *current_uA)
> {
> int sense_res;
> int err;
> @@ -102,7 +126,7 @@ static int ds2782_get_current(struct ds2782_info *info, int *current_uA)
> * The units of measurement for current are dependent on the value of
> * the sense resistor.
> */
> - err = ds2782_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
> + err = ds278x_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
> if (err)
> return err;
> if (sense_res_raw == 0) {
> @@ -113,14 +137,14 @@ static int ds2782_get_current(struct ds2782_info *info, int *current_uA)
>
> dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
> sense_res);
> - err = ds2782_read_reg16(info, DS2782_REG_CURRENT_MSB, &raw);
> + err = ds278x_read_reg16(info, DS2782_REG_CURRENT_MSB, &raw);
> if (err)
> return err;
> *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
> return 0;
> }
>
> -static int ds2782_get_voltage(struct ds2782_info *info, int *voltage_uA)
> +static int ds2782_get_voltage(struct ds278x_info *info, int *voltage_uA)
> {
> s16 raw;
> int err;
> @@ -129,36 +153,110 @@ static int ds2782_get_voltage(struct ds2782_info *info, int *voltage_uA)
> * Voltage is measured in units of 4.88mV. The voltage is stored as
> * a 10-bit number plus sign, in the upper bits of a 16-bit register
> */
> - err = ds2782_read_reg16(info, DS2782_REG_VOLT_MSB, &raw);
> + err = ds278x_read_reg16(info, DS2782_REG_VOLT_MSB, &raw);
> if (err)
> return err;
> *voltage_uA = (raw / 32) * 4800;
> return 0;
> }
>
> -static int ds2782_get_capacity(struct ds2782_info *info, int *capacity)
> +static int ds2782_get_capacity(struct ds278x_info *info, int *capacity)
> {
> int err;
> u8 raw;
>
> - err = ds2782_read_reg(info, DS2782_REG_RARC, &raw);
> + err = ds278x_read_reg(info, DS2782_REG_RARC, &raw);
> if (err)
> return err;
> *capacity = raw;
> return raw;
> }
>
> -static int ds2782_get_status(struct ds2782_info *info, int *status)
> +static int ds2786_get_temp(struct ds278x_info *info, int *temp)
> +{
> + s16 raw;
> + int err;
> +
> + /*
> + * Temperature is measured in units of 0.125 degrees celcius, the
> + * power_supply class measures temperature in tenths of degrees
> + * celsius. The temperature value is stored as a 10 bit number, plus
> + * sign in the upper bits of a 16 bit register.
> + */
> + err = ds278x_read_reg16(info, DS2786_REG_TEMP_MSB, &raw);
> + if (err)
> + return err;
> +
> + if (raw & DS278X_SIGN_BIT_MASK16)
> + *temp = -(((~raw >> 5)+1) * 125)/100;
> + else
> + *temp = ((raw >> 5) * 125)/100;
> +
> + return 0;
> +}

This is basically the same as the ds2782 version. See Jean's comments on
my original patch about the sign math:
http://www.mail-archive.com/linux-i2c@xxxxxxxxxxxxxxx/msg01220.html

> +static int ds2786_get_current(struct ds278x_info *info, int *current_uA)
> +{
> + int err;
> + s16 raw;
> +
> + err = ds278x_read_reg16(info, DS2786_REG_CURRENT_MSB, &raw);
> + if (err)
> + return err;
> +
> + if (raw & DS278X_SIGN_BIT_MASK16)
> + *current_uA = -(((~raw >> 4)+1) *
> + (DS2786_CURRENT_UNITS / info->rsns));
> + else
> + *current_uA = (raw >> 4) *
> + (DS2786_CURRENT_UNITS / info->rsns);
> + return 0;

Can we combine the implementations of the get_current function? Both
have get rsns (though in different ways) and eventually divide the
current register by the rsns value? Possibly move the get_rsns into
separate battery ops and attempt to coalesce these?

> +}
> +
> +static int ds2786_get_voltage(struct ds278x_info *info, int *voltage_uA)
> +{
> + s16 raw;
> + int err;
> +
> + /*
> + * Voltage is measured in units of 1.22mV. The voltage is stored as
> + * a 10-bit number plus sign, in the upper bits of a 16-bit register
> + */
> + err = ds278x_read_reg16(info, DS2786_REG_VOLT_MSB, &raw);
> + if (err)
> + return err;
> +
> + if (raw & DS278X_SIGN_BIT_MASK16)
> + *voltage_uA = -(((~raw >> 3)+1) * 1220);
> + else
> + *voltage_uA = (raw >> 3) * 1220;
> + return 0;
> +}

Again, if we move the multiplier value (1220 for ds2786 and 4800 for
ds2782) to the info structure then we can use the same code to get the
voltage for both chips.

> +static int ds2786_get_capacity(struct ds278x_info *info, int *capacity)
> +{
> + int err;
> + u8 raw;
> +
> + err = ds278x_read_reg(info, DS2786_REG_RARC, &raw);
> + if (err)
> + return err;
> + /* Relative capacity is displayed with resolution 0.5 % */
> + *capacity = raw/2 ;
> + return 0;
> +}

Same here, move the divider to the info structure (will be 1 for ds2782)
and combine the functions.

> +
> +static int ds278x_get_status(struct ds278x_info *info, int *status)
> {
> int err;
> int current_uA;
> int capacity;
>
> - err = ds2782_get_current(info, &current_uA);
> + err = info->ops->get_current(info, &current_uA);
> if (err)
> return err;
>
> - err = ds2782_get_capacity(info, &capacity);
> + err = info->ops->get_capacity(info, &capacity);
> if (err)
> return err;
>
> @@ -174,32 +272,32 @@ static int ds2782_get_status(struct ds2782_info *info, int *status)
> return 0;
> }
>
> -static int ds2782_battery_get_property(struct power_supply *psy,
> +static int ds278x_battery_get_property(struct power_supply *psy,
> enum power_supply_property prop,
> union power_supply_propval *val)
> {
> - struct ds2782_info *info = to_ds2782_info(psy);
> + struct ds278x_info *info = to_ds278x_info(psy);
> int ret;
>
> switch (prop) {
> case POWER_SUPPLY_PROP_STATUS:
> - ret = ds2782_get_status(info, &val->intval);
> + ret = ds278x_get_status(info, &val->intval);
> break;
>
> case POWER_SUPPLY_PROP_CAPACITY:
> - ret = ds2782_get_capacity(info, &val->intval);
> + ret = info->ops->get_capacity(info, &val->intval);
> break;
>
> case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> - ret = ds2782_get_voltage(info, &val->intval);
> + ret = info->ops->get_voltage(info, &val->intval);
> break;
>
> case POWER_SUPPLY_PROP_CURRENT_NOW:
> - ret = ds2782_get_current(info, &val->intval);
> + ret = info->ops->get_current(info, &val->intval);
> break;
>
> case POWER_SUPPLY_PROP_TEMP:
> - ret = ds2782_get_temp(info, &val->intval);
> + ret = info->ops->get_temp(info, &val->intval);
> break;
>
> default:
> @@ -209,7 +307,7 @@ static int ds2782_battery_get_property(struct power_supply *psy,
> return ret;
> }
>
> -static enum power_supply_property ds2782_battery_props[] = {
> +static enum power_supply_property ds278x_battery_props[] = {
> POWER_SUPPLY_PROP_STATUS,
> POWER_SUPPLY_PROP_CAPACITY,
> POWER_SUPPLY_PROP_VOLTAGE_NOW,
> @@ -217,18 +315,18 @@ static enum power_supply_property ds2782_battery_props[] = {
> POWER_SUPPLY_PROP_TEMP,
> };
>
> -static void ds2782_power_supply_init(struct power_supply *battery)
> +static void ds278x_power_supply_init(struct power_supply *battery)
> {
> battery->type = POWER_SUPPLY_TYPE_BATTERY;
> - battery->properties = ds2782_battery_props;
> - battery->num_properties = ARRAY_SIZE(ds2782_battery_props);
> - battery->get_property = ds2782_battery_get_property;
> + battery->properties = ds278x_battery_props;
> + battery->num_properties = ARRAY_SIZE(ds278x_battery_props);
> + battery->get_property = ds278x_battery_get_property;
> battery->external_power_changed = NULL;
> }
>
> -static int ds2782_battery_remove(struct i2c_client *client)
> +static int ds278x_battery_remove(struct i2c_client *client)
> {
> - struct ds2782_info *info = i2c_get_clientdata(client);
> + struct ds278x_info *info = i2c_get_clientdata(client);
>
> power_supply_unregister(&info->battery);
> kfree(info->battery.name);
> @@ -243,13 +341,38 @@ static int ds2782_battery_remove(struct i2c_client *client)
> return 0;
> }
>
> -static int ds2782_battery_probe(struct i2c_client *client,
> +static struct ds278x_battery_ops ds278x_ops[] = {
> + [0] = {
> + .get_temp = ds2782_get_temp,
> + .get_current = ds2782_get_current,
> + .get_voltage = ds2782_get_voltage,
> + .get_capacity = ds2782_get_capacity,
> + },
> + [1] = {
> + .get_temp = ds2786_get_temp,
> + .get_current = ds2786_get_current,
> + .get_voltage = ds2786_get_voltage,
> + .get_capacity = ds2786_get_capacity,
> + }
> +};
> +
> +static int ds278x_battery_probe(struct i2c_client *client,
> const struct i2c_device_id *id)
> {
> - struct ds2782_info *info;
> + struct ds278x_platform_data *pdata = client->dev.platform_data;
> + struct ds278x_info *info;
> int ret;
> int num;
>
> + /*
> + * ds2786 should have the sense resistor value set
> + * in the platform data .
> + */
> + if (id->driver_data == 1 && pdata == 0) {
> + dev_err(&client->dev, "missing platform data for ds2786\n");
> + return -EINVAL;
> + }
> +
> /* Get an ID for this battery */
> ret = idr_pre_get(&battery_id, GFP_KERNEL);
> if (ret == 0) {
> @@ -269,7 +392,7 @@ static int ds2782_battery_probe(struct i2c_client *client,
> goto fail_info;
> }
>
> - info->battery.name = kasprintf(GFP_KERNEL, "ds2782-%d", num);
> + info->battery.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);
> if (!info->battery.name) {
> ret = -ENOMEM;
> goto fail_name;
> @@ -277,7 +400,10 @@ static int ds2782_battery_probe(struct i2c_client *client,
>
> i2c_set_clientdata(client, info);
> info->client = client;
> - ds2782_power_supply_init(&info->battery);
> + info->id = num;
> + info->ops = &ds278x_ops[id->driver_data];
> + info->rsns = pdata->rsns;
> + ds278x_power_supply_init(&info->battery);
>
> ret = power_supply_register(&client->dev, &info->battery);
> if (ret) {
> @@ -300,31 +426,32 @@ fail_id:
> return ret;
> }
>
> -static const struct i2c_device_id ds2782_id[] = {
> +static const struct i2c_device_id ds278x_id[] = {
> {"ds2782", 0},
> + {"ds2786", 1},
> {},
> };
>
> -static struct i2c_driver ds2782_battery_driver = {
> +static struct i2c_driver ds278x_battery_driver = {
> .driver = {
> .name = "ds2782-battery",
> },
> - .probe = ds2782_battery_probe,
> - .remove = ds2782_battery_remove,
> - .id_table = ds2782_id,
> + .probe = ds278x_battery_probe,
> + .remove = ds278x_battery_remove,
> + .id_table = ds278x_id,
> };
>
> -static int __init ds2782_init(void)
> +static int __init ds278x_init(void)
> {
> - return i2c_add_driver(&ds2782_battery_driver);
> + return i2c_add_driver(&ds278x_battery_driver);
> }
> -module_init(ds2782_init);
> +module_init(ds278x_init);
>
> -static void __exit ds2782_exit(void)
> +static void __exit ds278x_exit(void)
> {
> - i2c_del_driver(&ds2782_battery_driver);
> + i2c_del_driver(&ds278x_battery_driver);
> }
> -module_exit(ds2782_exit);
> +module_exit(ds278x_exit);
>
> MODULE_AUTHOR("Ryan Mallon <ryan@xxxxxxxxxxxxxxxx>");
> MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
> diff --git a/include/linux/ds2782_battery.h b/include/linux/ds2782_battery.h
> new file mode 100644
> index 0000000..b4e281f
> --- /dev/null
> +++ b/include/linux/ds2782_battery.h
> @@ -0,0 +1,8 @@
> +#ifndef __LINUX_DS2782_BATTERY_H
> +#define __LINUX_DS2782_BATTERY_H
> +
> +struct ds278x_platform_data {
> + int rsns;
> +};
> +
> +#endif


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Ryan Mallon 5 Amuri Park, 404 Barbadoes St
ryan@xxxxxxxxxxxxxxxx PO Box 13 889, Christchurch 8013
http://www.bluewatersys.com New Zealand
Phone: +64 3 3779127 Freecall: Australia 1800 148 751
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