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Date: Sat, 19 Jan 2013 18:00:03 -0800
From: Anton Vorontsov <anton@...msg.org>
To: Pali Rohár <pali.rohar@...il.com>
Cc: David Woodhouse <dwmw2@...radead.org>,
linux-kernel@...r.kernel.org,
Mark Brown <broonie@...nsource.wolfsonmicro.com>
Subject: Re: [PATCH] power: bq27x00_battery: Export all battery registers via
sysfs
On Sat, Jan 19, 2013 at 03:01:43PM +0100, Pali Rohár wrote:
> bq27xxx batteries have a lot of properties, more than power_supply interface.
> Some of them can be usefull for userspace applications (like CI bit) but
> does not make sense to add bq specified property to power_supply interface.
> When bq27x00_battery is not loaded userspace application (like i2cget) can
> use /dev/i2c-* interface for raw access. But when kernel module is attached
> to i2c device, userspace applications cannot access it via /dev/i2c-*.
> Also it is not usefull for userspace to unload module before reading values
> form /dev/i2c-* and then load it again.
If it is useful for userspace applications, you probably do want to
make a proper interface for it? What is "CI" bit?
We were discussing it before, right?
http://permalink.gmane.org/gmane.linux.kernel/1220570
I said:
In any case, I just think that being able to access already bound
I2C devices from userspace might be a good thing for debugging,
but having such an interface per-driver is impractical.
So, I still think that making a generic interface is the way to go.
And Mark Brown said:
if this is a device that has registers that fit within regmap then the
regmap API provides a debugfs interface for dumping the register map as
standard.
...
The regmap debug file is a file of lines in the format 'regnum: value'
where both fields have a fixed width so should be easily parsable.
So, it seems that we have that interface already.
Here is the whole discussion:
http://comments.gmane.org/gmane.linux.kernel/1209421
Thanks,
> This patch exporting all battery registers to sysfs entry "registers" in
> battery power_supply directory. Format is "register=value" on separate line.
> Because length of registers are different for each bq battery more for loops
> are needed.
>
> Signed-off-by: Pali Rohár <pali.rohar@...il.com>
> ---
> drivers/power/bq27x00_battery.c | 98 +++++++++++++++++++++++++++++++++++++--
> 1 file changed, 95 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/power/bq27x00_battery.c b/drivers/power/bq27x00_battery.c
> index 7087d0d..af0f68f 100644
> --- a/drivers/power/bq27x00_battery.c
> +++ b/drivers/power/bq27x00_battery.c
> @@ -690,6 +690,90 @@ static void bq27x00_external_power_changed(struct power_supply *psy)
> schedule_delayed_work(&di->work, 0);
> }
>
> +/* code for register device access via sysfs */
> +
> +static ssize_t bq27x00_battery_sysfs_print_reg(struct bq27x00_device_info *di,
> + u8 reg, bool single, char *buf)
> +{
> + int ret = bq27x00_read(di, reg, single);
> + if (ret < 0)
> + return sprintf(buf, "%#.2x=error %d\n", reg, ret);
> + else
> + return sprintf(buf, "%#.2x=%#.2x\n", reg, ret);
> +}
> +
> +static ssize_t bq27x00_battery_sysfs_show_registers(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct power_supply *psy = dev_get_drvdata(dev);
> + struct bq27x00_device_info *di = container_of(psy,
> + struct bq27x00_device_info,
> + bat);
> + u8 reg;
> + ssize_t ret = 0;
> +
> + switch (di->chip) {
> +
> + case BQ27000:
> + for (reg=0x00; reg<=0x01; reg+=1)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, true, buf+ret);
> + for (reg=0x02; reg<=0x08; reg+=2)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, false, buf+ret);
> + for (reg=0x0A; reg<=0x0B; reg+=1)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, true, buf+ret);
> + for (reg=0x0C; reg<=0x2A; reg+=2)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, false, buf+ret);
> + for (reg=0x2C; reg<=0x7F; reg+=1)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, true, buf+ret);
> + break;
> +
> + case BQ27500:
> + for (reg=0x00; reg<=0x2C; reg+=2)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, false, buf+ret);
> + for (reg=0x2E; reg<=0x3B; reg+=1)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, true, buf+ret);
> + for (reg=0x3C; reg<=0x3C; reg+=2)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, false, buf+ret);
> + for (reg=0x3E; reg<=0x7F; reg+=1)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, true, buf+ret);
> + break;
> +
> + case BQ27425:
> + for (reg=0x00; reg<=0x3C; reg+=2)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, false, buf+ret);
> + for (reg=0x3E; reg<=0x7F; reg+=1)
> + ret += bq27x00_battery_sysfs_print_reg(di, reg, true, buf+ret);
> + break;
> +
> + }
> +
> + return ret;
> +}
> +
> +static DEVICE_ATTR(registers, S_IRUGO,
> + bq27x00_battery_sysfs_show_registers, NULL);
> +
> +static struct attribute *bq27x00_battery_sysfs_attributes[] = {
> + &dev_attr_registers.attr,
> + NULL,
> +};
> +
> +static const struct attribute_group bq27x00_battery_sysfs_attr_group = {
> + .attrs = bq27x00_battery_sysfs_attributes,
> +};
> +
> +static int bq27x00_battery_sysfs_init(struct bq27x00_device_info *di)
> +{
> + return sysfs_create_group(&di->bat.dev->kobj,
> + &bq27x00_battery_sysfs_attr_group);
> +}
> +
> +static void bq27x00_battery_sysfs_exit(struct bq27x00_device_info *di)
> +{
> + sysfs_remove_group(&di->bat.dev->kobj,
> + &bq27x00_battery_sysfs_attr_group);
> +}
> +
> static int bq27x00_powersupply_init(struct bq27x00_device_info *di)
> {
> int ret;
> @@ -705,15 +789,22 @@ static int bq27x00_powersupply_init(struct bq27x00_device_info *di)
> di->bat.get_property = bq27x00_battery_get_property;
> di->bat.external_power_changed = bq27x00_external_power_changed;
>
> - INIT_DELAYED_WORK(&di->work, bq27x00_battery_poll);
> - mutex_init(&di->lock);
> -
> ret = power_supply_register(di->dev, &di->bat);
> if (ret) {
> dev_err(di->dev, "failed to register battery: %d\n", ret);
> return ret;
> }
>
> + ret = bq27x00_battery_sysfs_init(di);
> + if (ret) {
> + dev_err(di->dev, "failed to register battery: %d\n", ret);
> + power_supply_unregister(&di->bat);
> + return ret;
> + }
> +
> + INIT_DELAYED_WORK(&di->work, bq27x00_battery_poll);
> + mutex_init(&di->lock);
> +
> dev_info(di->dev, "support ver. %s enabled\n", DRIVER_VERSION);
>
> bq27x00_update(di);
> @@ -733,6 +824,7 @@ static void bq27x00_powersupply_unregister(struct bq27x00_device_info *di)
>
> cancel_delayed_work_sync(&di->work);
>
> + bq27x00_battery_sysfs_exit(di);
> power_supply_unregister(&di->bat);
>
> mutex_destroy(&di->lock);
> --
> 1.7.10.4
--
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