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Date:	Fri, 14 Feb 2014 15:49:40 +0100
From:	Belisko Marek <marek.belisko@...il.com>
To:	Mark Rutland <mark.rutland@....com>
Cc:	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	Pawel Moll <Pawel.Moll@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	"galak@...eaurora.org" <galak@...eaurora.org>,
	"rob@...dley.net" <rob@...dley.net>,
	"dbaryshkov@...il.com" <dbaryshkov@...il.com>,
	"dwmw2@...radead.org" <dwmw2@...radead.org>,
	"grant.likely@...aro.org" <grant.likely@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"hns@...delico.com" <hns@...delico.com>
Subject: Re: [PATCH] power: twl4030_madc_battery: Add device tree support.

On Fri, Feb 14, 2014 at 2:43 PM, Mark Rutland <mark.rutland@....com> wrote:
> On Fri, Feb 14, 2014 at 01:24:19PM +0000, Marek Belisko wrote:
>> Signed-off-by: Marek Belisko <marek@...delico.com>
>> ---
>>  .../bindings/power_supply/twl4030_madc_battery.txt |  15 +++
>>  drivers/power/twl4030_madc_battery.c               | 109 +++++++++++++++++++++
>>  2 files changed, 124 insertions(+)
>>  create mode 100644 Documentation/devicetree/bindings/power_supply/twl4030_madc_battery.txt
>>
>> diff --git a/Documentation/devicetree/bindings/power_supply/twl4030_madc_battery.txt b/Documentation/devicetree/bindings/power_supply/twl4030_madc_battery.txt
>> new file mode 100644
>> index 0000000..bebc876
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/power_supply/twl4030_madc_battery.txt
>> @@ -0,0 +1,15 @@
>> +twl4030_madc_battery
>> +
>> +Required properties:
>> + - compatible : "ti,twl4030-madc-battery"
>> + - capacity : battery capacity in uAh
>> + - charging-calibration-data : list of voltage(mV):level(%) values for charging calibration (see example)
>> + - discharging-calibration-data : list of voltage(mV):level(%) values for discharging calibration (see example)
>> +
>> +Example:
>> +     madc-battery {
>> +             compatible = "ti,twl4030-madc-battery";
>> +             capacity = <1200000>;
>> +             charging-calibration-data = <4200 100 4100 75 4000 55 3900 25 3800 5 3700 2 3600 1 3300 0>;
>> +             discharging-calibration-data = <4200 100 4100 95 4000 70 3800 50 3700 10 3600 5 3300 0>;
>
> Please bracket list entries individually.
OK.
>
>> +     };
>> diff --git a/drivers/power/twl4030_madc_battery.c b/drivers/power/twl4030_madc_battery.c
>> index 7ef445a..2843382 100644
>> --- a/drivers/power/twl4030_madc_battery.c
>> +++ b/drivers/power/twl4030_madc_battery.c
>> @@ -19,6 +19,7 @@
>>  #include <linux/sort.h>
>>  #include <linux/i2c/twl4030-madc.h>
>>  #include <linux/power/twl4030_madc_battery.h>
>> +#include <linux/of.h>
>>
>>  struct twl4030_madc_battery {
>>       struct power_supply psy;
>> @@ -188,6 +189,110 @@ static int twl4030_cmp(const void *a, const void *b)
>>               ((struct twl4030_madc_bat_calibration *)a)->voltage;
>>  }
>>
>> +#ifdef CONFIG_OF
>> +static struct twl4030_madc_bat_platform_data *
>> +     twl4030_madc_dt_probe(struct platform_device *pdev)
>> +{
>> +     struct twl4030_madc_bat_platform_data *pdata;
>> +     struct device_node *np = pdev->dev.of_node;
>> +     struct property *prop;
>> +     int ret;
>> +     int sz, i, j = 0;
>> +
>> +     pdata = devm_kzalloc(&pdev->dev,
>> +                     sizeof(struct twl4030_madc_bat_platform_data),
>> +                     GFP_KERNEL);
>> +     if (!pdata)
>> +             return ERR_PTR(-ENOMEM);
>> +
>> +     ret = of_property_read_u32(np, "capacity", &pdata->capacity);
>> +     if (ret != 0)
>> +             return ERR_PTR(-EINVAL);
>> +
>> +     /* parse and prepare charging data */
>> +     prop = of_find_property(np, "charging-calibration-data", &sz);
>> +     if (!prop)
>> +             return ERR_PTR(-EINVAL);
>> +
>> +     if (sz % 2) {
>> +             dev_warn(&pdev->dev, "Count of charging-calibration-data must be even!\n");
>> +             return ERR_PTR(-EINVAL);
>> +     }
>
> As sz is in bytes this checks that the property is a multiple of 2
> bytes, not that it has an even number of u32 elements.
>
> Heiko Stübner recently added of_property_count_u32_elems [1,2]. Use that
> instead.
OK I'll convert it to that approach. Then seems code will be much
easier. Thanks for pointing to it.
>
>> +
>> +     sz /= sizeof(u32);
>> +
>> +     {
>> +             u32 data[sz];
>> +
>> +             ret = of_property_read_u32_array(np,
>> +                             "charging-calibration-data", &data[0], sz);
>> +             if (ret)
>> +                     return ERR_PTR(ret);
>
> Why not just allocate then try to read, possibly having to free if the
> read fails?
>
> Otherwise we're trying to put an arbitrarily large value onto the stack
> for no good reason.
>
>> +
>> +             pdata->charging = devm_kzalloc(&pdev->dev,
>> +                             sizeof(struct twl4030_madc_bat_calibration) * (sz / 2),
>> +                             GFP_KERNEL);
>> +
>> +             for (i = 0; i < sz; i += 2) {
>> +                     pdata->charging[j].voltage = data[i];
>> +                     pdata->charging[j].level = data[i+1];
>> +                     j++;
>
> Why not have (i = 0; i < sz/2; i++), and get rid of j?
>
>> +             }
>> +
>> +             pdata->charging_size = sz / 2;
>> +     }
>> +
>> +     /* parse and prepare discharging data */
>> +     prop = of_find_property(np, "discharging-calibration-data", &sz);
>> +     if (!prop)
>> +             return ERR_PTR(-EINVAL);
>> +
>> +     if (sz % 2) {
>> +             dev_warn(&pdev->dev, "Count of discharging-calibration-data must be even!\n");
>> +             return ERR_PTR(-EINVAL);
>> +     }
>
> This has the same issues as with charging-calibration-data.
>
> Thanks,
> Mark.
>
> [1] http://www.spinics.net/lists/devicetree/msg21358.html
> [2] http://www.spinics.net/lists/devicetree/msg21502.html

BR,

marek

-- 
as simple and primitive as possible
-------------------------------------------------
Marek Belisko - OPEN-NANDRA
Freelance Developer

Ruska Nova Ves 219 | Presov, 08005 Slovak Republic
Tel: +421 915 052 184
skype: marekwhite
twitter: #opennandra
web: http://open-nandra.com
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