[PATCH] rtc: ds1307: add trickle charger device tree binding

[PATCH] rtc: ds1307: add trickle charger device tree binding

[Matti Vaittinen]

Patch adding support for specifying trickle charger setup from device
tree. Patch is based on linux-next tree.


Some DS13XX devices have "trickle chargers". Introduce a device tree binding
for specifying the setup and register values.

Signed-off-by: Matti Vaittinen <matti.vaittinen@nsn.com>
---
 .../devicetree/bindings/i2c/trivial-devices.txt    |  1 -
 .../devicetree/bindings/rtc/dallas,ds1339.txt      | 19 ++++++++++
 drivers/rtc/rtc-ds1307.c                           | 44 ++++++++++++++++++++--
 3 files changed, 59 insertions(+), 5 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1339.txt

diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index 6af570e..e9206a4 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -35,7 +35,6 @@ catalyst,24c32		i2c serial eeprom
 cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
 dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
 dallas,ds1338		I2C RTC with 56-Byte NV RAM
-dallas,ds1339		I2C Serial Real-Time Clock
 dallas,ds1340		I2C RTC with Trickle Charger
 dallas,ds1374		I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
 dallas,ds1631		High-Precision Digital Thermometer
diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
new file mode 100644
index 0000000..9faf40e
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
@@ -0,0 +1,19 @@
+* Dallas DS1339		I2C Serial Real-Time Clock
+
+Required properties:
+- compatible: Should contain "dallas,ds1339".
+- reg: I2C address for chip
+
+Optional properties:
+- trickle_setup : Used Trickle Charger configuration,
+        corresponding to 5 lowest bits in trickle charger register.
+- trickle_reg   : Trickle charger register address. Defaults to 0x10 for ds1339.
+
+Example:
+	ds1339: rtc@68 {
+		compatible = "dallas,ds1339";
+        trickle_setup= <0x5>;
+		reg = <0x68>;
+	};
+
+
diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index f03d5ba..f9b1244 100644
--- a/drivers/rtc/rtc-ds1307.c
+++ b/drivers/rtc/rtc-ds1307.c
@@ -126,9 +126,10 @@ struct chip_desc {
 	u16			nvram_offset;
 	u16			nvram_size;
 	u16			trickle_charger_reg;
+	u8		  trickle_charger_setup;
 };
 
-static const struct chip_desc chips[last_ds_type] = {
+static struct chip_desc chips[last_ds_type] = {
 	[ds_1307] = {
 		.nvram_offset	= 8,
 		.nvram_size	= 56,
@@ -835,13 +836,37 @@ ds1307_nvram_write(struct file *filp, struct kobject *kobj,
 
 /*----------------------------------------------------------------------*/
 
+static void trickle_charger_of_init(struct chip_desc *chip,
+			struct device_node *node)
+{
+	int plen = 0;
+	const uint32_t *setup;
+	const uint32_t *reg;
+
+	setup = of_get_property(node, "trickle_setup" , &plen);
+	if (plen != 4)
+		goto out;
+	chip->trickle_charger_setup = (u8)*setup;
+	plen = 0;
+	reg = of_get_property(node, "trickle_reg" , &plen);
+	if (plen == 4)
+		chip->trickle_charger_reg = (u16)*reg;
+	return;
+out:
+	pr_debug("%s: No trickle charger data in dt for %s rtc chip\n",
+	    __func__, (node && node->name)?node->name:"ds13XX");
+}
+
+/*----------------------------------------------------------------------*/
+
+
 static int ds1307_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
 	struct ds1307		*ds1307;
 	int			err = -ENODEV;
 	int			tmp;
-	const struct chip_desc	*chip = &chips[id->driver_data];
+	struct chip_desc	*chip = &chips[id->driver_data];
 	struct i2c_adapter	*adapter = to_i2c_adapter(client->dev.parent);
 	bool			want_irq = false;
 	unsigned char		*buf;
@@ -866,9 +891,20 @@ static int ds1307_probe(struct i2c_client *client,
 	ds1307->client	= client;
 	ds1307->type	= id->driver_data;
 
-	if (pdata && pdata->trickle_charger_setup && chip->trickle_charger_reg)
+	if (!pdata && client->dev.of_node)
+		trickle_charger_of_init(chip, client->dev.of_node);
+		/* Get trickle property */
+	else if (pdata && pdata->trickle_charger_setup)
+		chip->trickle_charger_setup = pdata->trickle_charger_setup;
+
+	if (chip->trickle_charger_setup && chip->trickle_charger_reg) {
+		dev_dbg(&client->dev, "writing trickle charger info 0x%x to 0x%x\n",
+		    DS13XX_TRICKLE_CHARGER_MAGIC | chip->trickle_charger_setup,
+		    chip->trickle_charger_reg);
 		i2c_smbus_write_byte_data(client, chip->trickle_charger_reg,
-			DS13XX_TRICKLE_CHARGER_MAGIC | pdata->trickle_charger_setup);
+		    DS13XX_TRICKLE_CHARGER_MAGIC |
+		    chip->trickle_charger_setup);
+	}
 
 	buf = ds1307->regs;
 	if (i2c_check_functionality(adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
-- 
1.8.3.1


-- 
=============================================

Matti Vaittinen
Senile SW Specialist
FINLAND 

~~ When things go utterly wrong vim users can always type :help! ~~

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Mark Rutland]

On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> Patch adding support for specifying trickle charger setup from device
> tree. Patch is based on linux-next tree.
> 
> 
> Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> for specifying the setup and register values.
> 
> Signed-off-by: Matti Vaittinen <matti.vaittinen@nsn.com>
> ---
>  .../devicetree/bindings/i2c/trivial-devices.txt    |  1 -
>  .../devicetree/bindings/rtc/dallas,ds1339.txt      | 19 ++++++++++
>  drivers/rtc/rtc-ds1307.c                           | 44 ++++++++++++++++++++--
>  3 files changed, 59 insertions(+), 5 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> 
> diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> index 6af570e..e9206a4 100644
> --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> @@ -35,7 +35,6 @@ catalyst,24c32		i2c serial eeprom
>  cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
>  dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
>  dallas,ds1338		I2C RTC with 56-Byte NV RAM
> -dallas,ds1339		I2C Serial Real-Time Clock
>  dallas,ds1340		I2C RTC with Trickle Charger
>  dallas,ds1374		I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
>  dallas,ds1631		High-Precision Digital Thermometer
> diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> new file mode 100644
> index 0000000..9faf40e
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> @@ -0,0 +1,19 @@
> +* Dallas DS1339		I2C Serial Real-Time Clock
> +
> +Required properties:
> +- compatible: Should contain "dallas,ds1339".
> +- reg: I2C address for chip
> +
> +Optional properties:
> +- trickle_setup : Used Trickle Charger configuration,
> +        corresponding to 5 lowest bits in trickle charger register.

s/_/-/ in property names please.

What do these bits do? is there any documentation available?

Why do they need to be in the DT?

Why do we not have a higher-level description?

> +- trickle_reg   : Trickle charger register address. Defaults to 0x10 for ds1339.

Is this expected to change? Why does this need to be in the DT?

> +
> +Example:
> +	ds1339: rtc@68 {
> +		compatible = "dallas,ds1339";
> +        trickle_setup= <0x5>;
> +		reg = <0x68>;
> +	};
> +
> +
> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> index f03d5ba..f9b1244 100644
> --- a/drivers/rtc/rtc-ds1307.c
> +++ b/drivers/rtc/rtc-ds1307.c
> @@ -126,9 +126,10 @@ struct chip_desc {
>  	u16			nvram_offset;
>  	u16			nvram_size;
>  	u16			trickle_charger_reg;
> +	u8		  trickle_charger_setup;
>  };
>  
> -static const struct chip_desc chips[last_ds_type] = {
> +static struct chip_desc chips[last_ds_type] = {
>  	[ds_1307] = {
>  		.nvram_offset	= 8,
>  		.nvram_size	= 56,
> @@ -835,13 +836,37 @@ ds1307_nvram_write(struct file *filp, struct kobject *kobj,
>  
>  /*----------------------------------------------------------------------*/
>  
> +static void trickle_charger_of_init(struct chip_desc *chip,
> +			struct device_node *node)
> +{
> +	int plen = 0;
> +	const uint32_t *setup;
> +	const uint32_t *reg;
> +
> +	setup = of_get_property(node, "trickle_setup" , &plen);
> +	if (plen != 4)
> +		goto out;
> +	chip->trickle_charger_setup = (u8)*setup;

This isn't endian-clean, and the casting is unnecessary.

Use the of_property_read_u32 accessor, with a u32 temporary variable.

> +	plen = 0;
> +	reg = of_get_property(node, "trickle_reg" , &plen);
> +	if (plen == 4)
> +		chip->trickle_charger_reg = (u16)*reg;

Likewise.

Mark.

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Guenter Roeck]

On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > Patch adding support for specifying trickle charger setup from device
> > tree. Patch is based on linux-next tree.
> > 
> > 
> > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > for specifying the setup and register values.
> > 
> > Signed-off-by: Matti Vaittinen <matti.vaittinen@nsn.com>
> > ---
> >  .../devicetree/bindings/i2c/trivial-devices.txt    |  1 -
> >  .../devicetree/bindings/rtc/dallas,ds1339.txt      | 19 ++++++++++
> >  drivers/rtc/rtc-ds1307.c                           | 44 ++++++++++++++++++++--
> >  3 files changed, 59 insertions(+), 5 deletions(-)
> >  create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > 
> > diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > index 6af570e..e9206a4 100644
> > --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > @@ -35,7 +35,6 @@ catalyst,24c32		i2c serial eeprom
> >  cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
> >  dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
> >  dallas,ds1338		I2C RTC with 56-Byte NV RAM
> > -dallas,ds1339		I2C Serial Real-Time Clock
> >  dallas,ds1340		I2C RTC with Trickle Charger
> >  dallas,ds1374		I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
> >  dallas,ds1631		High-Precision Digital Thermometer
> > diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > new file mode 100644
> > index 0000000..9faf40e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > @@ -0,0 +1,19 @@
> > +* Dallas DS1339		I2C Serial Real-Time Clock
> > +
> > +Required properties:
> > +- compatible: Should contain "dallas,ds1339".
> > +- reg: I2C address for chip
> > +
> > +Optional properties:
> > +- trickle_setup : Used Trickle Charger configuration,
> > +        corresponding to 5 lowest bits in trickle charger register.
> 
The value is provided via platform data, so it is platform specific
and presumably needs to be configurable. I did, however, not find
a single in-kernel driver which is actually setting it.
So this is a good question.

> s/_/-/ in property names please.
> 
> What do these bits do? is there any documentation available?
> 
> Why do they need to be in the DT?
> 
> Why do we not have a higher-level description?
> 
> > +- trickle_reg   : Trickle charger register address. Defaults to 0x10 for ds1339.
> 
> Is this expected to change? Why does this need to be in the DT?
> 
A quick look into the code suggests that this is a chip specific register,
and the register address is set by the driver depending on the chip type.
I don't think it should be configurable via dt.

Guenter

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Mark Rutland]

On Thu, Aug 28, 2014 at 04:51:57PM +0100, Guenter Roeck wrote:
> On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> > On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > > Patch adding support for specifying trickle charger setup from device
> > > tree. Patch is based on linux-next tree.
> > > 
> > > 
> > > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > > for specifying the setup and register values.
> > > 
> > > Signed-off-by: Matti Vaittinen <matti.vaittinen@nsn.com>
> > > ---
> > >  .../devicetree/bindings/i2c/trivial-devices.txt    |  1 -
> > >  .../devicetree/bindings/rtc/dallas,ds1339.txt      | 19 ++++++++++
> > >  drivers/rtc/rtc-ds1307.c                           | 44 ++++++++++++++++++++--
> > >  3 files changed, 59 insertions(+), 5 deletions(-)
> > >  create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > 
> > > diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > index 6af570e..e9206a4 100644
> > > --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > @@ -35,7 +35,6 @@ catalyst,24c32		i2c serial eeprom
> > >  cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
> > >  dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
> > >  dallas,ds1338		I2C RTC with 56-Byte NV RAM
> > > -dallas,ds1339		I2C Serial Real-Time Clock
> > >  dallas,ds1340		I2C RTC with Trickle Charger
> > >  dallas,ds1374		I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
> > >  dallas,ds1631		High-Precision Digital Thermometer
> > > diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > new file mode 100644
> > > index 0000000..9faf40e
> > > --- /dev/null
> > > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > @@ -0,0 +1,19 @@
> > > +* Dallas DS1339		I2C Serial Real-Time Clock
> > > +
> > > +Required properties:
> > > +- compatible: Should contain "dallas,ds1339".
> > > +- reg: I2C address for chip
> > > +
> > > +Optional properties:
> > > +- trickle_setup : Used Trickle Charger configuration,
> > > +        corresponding to 5 lowest bits in trickle charger register.
> > 
> The value is provided via platform data, so it is platform specific
> and presumably needs to be configurable. I did, however, not find
> a single in-kernel driver which is actually setting it.
> So this is a good question.

I'm uncomfortable adding a field we don't understand to DT.

Is there any publicly-available documentation for the device?

> > s/_/-/ in property names please.
> > 
> > What do these bits do? is there any documentation available?
> > 
> > Why do they need to be in the DT?
> > 
> > Why do we not have a higher-level description?
> > 
> > > +- trickle_reg   : Trickle charger register address. Defaults to 0x10 for ds1339.
> > 
> > Is this expected to change? Why does this need to be in the DT?
> > 
> A quick look into the code suggests that this is a chip specific register,
> and the register address is set by the driver depending on the chip type.
> I don't think it should be configurable via dt.

Ok.

Cheers,
Mark.

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Guenter Roeck]

On Thu, Aug 28, 2014 at 05:10:25PM +0100, Mark Rutland wrote:
> On Thu, Aug 28, 2014 at 04:51:57PM +0100, Guenter Roeck wrote:
> > On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> > > On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > > > Patch adding support for specifying trickle charger setup from device
> > > > tree. Patch is based on linux-next tree.
> > > > 
> > > > 
> > > > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > > > for specifying the setup and register values.
> > > > 
> > > > Signed-off-by: Matti Vaittinen <matti.vaittinen@nsn.com>
> > > > ---
> > > >  .../devicetree/bindings/i2c/trivial-devices.txt    |  1 -
> > > >  .../devicetree/bindings/rtc/dallas,ds1339.txt      | 19 ++++++++++
> > > >  drivers/rtc/rtc-ds1307.c                           | 44 ++++++++++++++++++++--
> > > >  3 files changed, 59 insertions(+), 5 deletions(-)
> > > >  create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > 
> > > > diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > index 6af570e..e9206a4 100644
> > > > --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > @@ -35,7 +35,6 @@ catalyst,24c32		i2c serial eeprom
> > > >  cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
> > > >  dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
> > > >  dallas,ds1338		I2C RTC with 56-Byte NV RAM
> > > > -dallas,ds1339		I2C Serial Real-Time Clock
> > > >  dallas,ds1340		I2C RTC with Trickle Charger
> > > >  dallas,ds1374		I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
> > > >  dallas,ds1631		High-Precision Digital Thermometer
> > > > diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > new file mode 100644
> > > > index 0000000..9faf40e
> > > > --- /dev/null
> > > > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > @@ -0,0 +1,19 @@
> > > > +* Dallas DS1339		I2C Serial Real-Time Clock
> > > > +
> > > > +Required properties:
> > > > +- compatible: Should contain "dallas,ds1339".
> > > > +- reg: I2C address for chip
> > > > +
> > > > +Optional properties:
> > > > +- trickle_setup : Used Trickle Charger configuration,
> > > > +        corresponding to 5 lowest bits in trickle charger register.
> > > 
> > The value is provided via platform data, so it is platform specific
> > and presumably needs to be configurable. I did, however, not find
> > a single in-kernel driver which is actually setting it.
> > So this is a good question.
> 
> I'm uncomfortable adding a field we don't understand to DT.
> 
> Is there any publicly-available documentation for the device?
> 

Lots ;-)

http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
http://datasheets.maximintegrated.com/en/ds/DS3231.pdf

Code suggests that DS1339, DS1339, and DS1340 have the register.

Looking into the datasheets, the configuration consists of two parts:
- diode connected or not
- trickle charger resistor value (250, 2000, or 4000 ohm)

Given that, it seems to me that those values should be configured
explicitly instead of using a binary value, and that the driver
should perform the conversion from dt entry to register value.

Note that the relevant bits are the lower 4 bits, not the
lower 5 bits, so the above text is wrong.

Guenter

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Jason Cooper]

On Thu, Aug 28, 2014 at 09:48:25AM -0700, Guenter Roeck wrote:
> On Thu, Aug 28, 2014 at 05:10:25PM +0100, Mark Rutland wrote:
> > On Thu, Aug 28, 2014 at 04:51:57PM +0100, Guenter Roeck wrote:
> > > On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> > > > On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > > > > Patch adding support for specifying trickle charger setup from device
> > > > > tree. Patch is based on linux-next tree.
> > > > > 
> > > > > 
> > > > > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > > > > for specifying the setup and register values.
> > > > > 
> > > > > Signed-off-by: Matti Vaittinen <matti.vaittinen@nsn.com>
> > > > > ---
> > > > >  .../devicetree/bindings/i2c/trivial-devices.txt    |  1 -
> > > > >  .../devicetree/bindings/rtc/dallas,ds1339.txt      | 19 ++++++++++
> > > > >  drivers/rtc/rtc-ds1307.c                           | 44 ++++++++++++++++++++--
> > > > >  3 files changed, 59 insertions(+), 5 deletions(-)
> > > > >  create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > 
> > > > > diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > > index 6af570e..e9206a4 100644
> > > > > --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > > +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > > @@ -35,7 +35,6 @@ catalyst,24c32		i2c serial eeprom
> > > > >  cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
> > > > >  dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
> > > > >  dallas,ds1338		I2C RTC with 56-Byte NV RAM
> > > > > -dallas,ds1339		I2C Serial Real-Time Clock
> > > > >  dallas,ds1340		I2C RTC with Trickle Charger
> > > > >  dallas,ds1374		I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
> > > > >  dallas,ds1631		High-Precision Digital Thermometer
> > > > > diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > new file mode 100644
> > > > > index 0000000..9faf40e
> > > > > --- /dev/null
> > > > > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > @@ -0,0 +1,19 @@
> > > > > +* Dallas DS1339		I2C Serial Real-Time Clock
> > > > > +
> > > > > +Required properties:
> > > > > +- compatible: Should contain "dallas,ds1339".
> > > > > +- reg: I2C address for chip
> > > > > +
> > > > > +Optional properties:
> > > > > +- trickle_setup : Used Trickle Charger configuration,
> > > > > +        corresponding to 5 lowest bits in trickle charger register.
> > > > 
> > > The value is provided via platform data, so it is platform specific
> > > and presumably needs to be configurable. I did, however, not find
> > > a single in-kernel driver which is actually setting it.
> > > So this is a good question.
> > 
> > I'm uncomfortable adding a field we don't understand to DT.
> > 
> > Is there any publicly-available documentation for the device?
> > 
> 
> Lots ;-)
> 
> http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
> 
> Code suggests that DS1339, DS1339, and DS1340 have the register.
> 
> Looking into the datasheets, the configuration consists of two parts:
> - diode connected or not
> - trickle charger resistor value (250, 2000, or 4000 ohm)
> 
> Given that, it seems to me that those values should be configured
> explicitly instead of using a binary value, and that the driver
> should perform the conversion from dt entry to register value.

iiuc, there is no way for the kernel to determine what is being trickle
charged, and thus no way to determine how it should set this register.

It may be a bit of overkill, but I think a DT macro would be the most
maintainable solution here:

#define DS1339_TRCKL_DIODE   0x08
#define DS1339_TRCKL_NODIODE 0x04
#define DS1339_TRCKL_R250    0x01
#define DS1339_TRCKL_R2000   0x02
#define DS1339_TRCKL_R4000   0x03

trickle_setup = <DS1339_TRCKL_DIODE | DS1339_TRCKL_R250>;

And the driver would take care of oring it with the enable pattern.

thx,

Jason.

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Guenter Roeck]

On Thu, Aug 28, 2014 at 01:28:42PM -0400, Jason Cooper wrote:
> On Thu, Aug 28, 2014 at 09:48:25AM -0700, Guenter Roeck wrote:
> > On Thu, Aug 28, 2014 at 05:10:25PM +0100, Mark Rutland wrote:
> > > On Thu, Aug 28, 2014 at 04:51:57PM +0100, Guenter Roeck wrote:
> > > > On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> > > > > On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > > > > > Patch adding support for specifying trickle charger setup from device
> > > > > > tree. Patch is based on linux-next tree.
> > > > > > 
> > > > > > 
> > > > > > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > > > > > for specifying the setup and register values.
> > > > > > 
> > > > > > Signed-off-by: Matti Vaittinen <matti.vaittinen@nsn.com>
> > > > > > ---
> > > > > >  .../devicetree/bindings/i2c/trivial-devices.txt    |  1 -
> > > > > >  .../devicetree/bindings/rtc/dallas,ds1339.txt      | 19 ++++++++++
> > > > > >  drivers/rtc/rtc-ds1307.c                           | 44 ++++++++++++++++++++--
> > > > > >  3 files changed, 59 insertions(+), 5 deletions(-)
> > > > > >  create mode 100644 Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > > 
> > > > > > diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > > > index 6af570e..e9206a4 100644
> > > > > > --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > > > +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > > > > > @@ -35,7 +35,6 @@ catalyst,24c32		i2c serial eeprom
> > > > > >  cirrus,cs42l51		Cirrus Logic CS42L51 audio codec
> > > > > >  dallas,ds1307		64 x 8, Serial, I2C Real-Time Clock
> > > > > >  dallas,ds1338		I2C RTC with 56-Byte NV RAM
> > > > > > -dallas,ds1339		I2C Serial Real-Time Clock
> > > > > >  dallas,ds1340		I2C RTC with Trickle Charger
> > > > > >  dallas,ds1374		I2C, 32-Bit Binary Counter Watchdog RTC with Trickle Charger and Reset Input/Output
> > > > > >  dallas,ds1631		High-Precision Digital Thermometer
> > > > > > diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > > new file mode 100644
> > > > > > index 0000000..9faf40e
> > > > > > --- /dev/null
> > > > > > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > > @@ -0,0 +1,19 @@
> > > > > > +* Dallas DS1339		I2C Serial Real-Time Clock
> > > > > > +
> > > > > > +Required properties:
> > > > > > +- compatible: Should contain "dallas,ds1339".
> > > > > > +- reg: I2C address for chip
> > > > > > +
> > > > > > +Optional properties:
> > > > > > +- trickle_setup : Used Trickle Charger configuration,
> > > > > > +        corresponding to 5 lowest bits in trickle charger register.
> > > > > 
> > > > The value is provided via platform data, so it is platform specific
> > > > and presumably needs to be configurable. I did, however, not find
> > > > a single in-kernel driver which is actually setting it.
> > > > So this is a good question.
> > > 
> > > I'm uncomfortable adding a field we don't understand to DT.
> > > 
> > > Is there any publicly-available documentation for the device?
> > > 
> > 
> > Lots ;-)
> > 
> > http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> > http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> > http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> > http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> > http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> > http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> > http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
> > 
> > Code suggests that DS1339, DS1339, and DS1340 have the register.
> > 
> > Looking into the datasheets, the configuration consists of two parts:
> > - diode connected or not
> > - trickle charger resistor value (250, 2000, or 4000 ohm)
> > 
> > Given that, it seems to me that those values should be configured
> > explicitly instead of using a binary value, and that the driver
> > should perform the conversion from dt entry to register value.
> 
> iiuc, there is no way for the kernel to determine what is being trickle
> charged, and thus no way to determine how it should set this register.
> 
> It may be a bit of overkill, but I think a DT macro would be the most
> maintainable solution here:
> 
> #define DS1339_TRCKL_DIODE   0x08
> #define DS1339_TRCKL_NODIODE 0x04
> #define DS1339_TRCKL_R250    0x01
> #define DS1339_TRCKL_R2000   0x02
> #define DS1339_TRCKL_R4000   0x03
> 
> trickle_setup = <DS1339_TRCKL_DIODE | DS1339_TRCKL_R250>;
> 
> And the driver would take care of oring it with the enable pattern.
> 

Yes, that sounds reasonable as well.

Guenter

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Matti Vaittinen]

On Thu, Aug 28, 2014 at 10:40:34AM -0700, ext Guenter Roeck wrote:
> On Thu, Aug 28, 2014 at 01:28:42PM -0400, Jason Cooper wrote:
> > On Thu, Aug 28, 2014 at 09:48:25AM -0700, Guenter Roeck wrote:
> > > On Thu, Aug 28, 2014 at 05:10:25PM +0100, Mark Rutland wrote:
> > > > On Thu, Aug 28, 2014 at 04:51:57PM +0100, Guenter Roeck wrote:
> > > > > On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> > > > > > On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > > > > > > Patch adding support for specifying trickle charger setup from device
> > > > > > > tree. Patch is based on linux-next tree.
> > > > > > > 
> > > > > > > 
> > > > > > > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > > > > > > for specifying the setup and register values.
> > > > > > > 
> > > > > > > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > > > @@ -0,0 +1,19 @@
> > > > > > > +* Dallas DS1339		I2C Serial Real-Time Clock
> > > > > > > +
> > > > > > > +Required properties:
> > > > > > > +- compatible: Should contain "dallas,ds1339".
> > > > > > > +- reg: I2C address for chip
> > > > > > > +
> > > > > > > +Optional properties:
> > > > > > > +- trickle_setup : Used Trickle Charger configuration,
> > > > > > > +        corresponding to 5 lowest bits in trickle charger register.
> > > > > > 
> > > > > The value is provided via platform data, so it is platform specific
> > > > > and presumably needs to be configurable. I did, however, not find
> > > > > a single in-kernel driver which is actually setting it.
> > > > > So this is a good question.
> > > > 
> > > > I'm uncomfortable adding a field we don't understand to DT.
> > > > 
> > > > Is there any publicly-available documentation for the device?
> > > > 
> > > 
> > > Lots ;-)
> > > 
> > > http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> > > http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> > > http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> > > http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> > > http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> > > http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> > > http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
> > > 
> > > Code suggests that DS1339, DS1339, and DS1340 have the register.
> > > 
> > > Looking into the datasheets, the configuration consists of two parts:
> > > - diode connected or not
> > > - trickle charger resistor value (250, 2000, or 4000 ohm)
> > > 
> > > Given that, it seems to me that those values should be configured
> > > explicitly instead of using a binary value, and that the driver
> > > should perform the conversion from dt entry to register value.
> > 
> > iiuc, there is no way for the kernel to determine what is being trickle
> > charged, and thus no way to determine how it should set this register.
> > 
> > It may be a bit of overkill, but I think a DT macro would be the most
> > maintainable solution here:
> > 
> > #define DS1339_TRCKL_DIODE   0x08
> > #define DS1339_TRCKL_NODIODE 0x04
> > #define DS1339_TRCKL_R250    0x01
> > #define DS1339_TRCKL_R2000   0x02
> > #define DS1339_TRCKL_R4000   0x03
> > 
> > trickle_setup = <DS1339_TRCKL_DIODE | DS1339_TRCKL_R250>;
> > 
> > And the driver would take care of oring it with the enable pattern.
> > 
> 
> Yes, that sounds reasonable as well.
> 
I thought of this too. However the ds1307 seems to be designed to work
with bunch of chips. What then when next chip supported by this driver
introduces 75, 1000 and 5000 ohm resistors? Or something else. (Or add
some other configuration). I do not see this approach to be maintainable
in long run. I see strong possibility of polluting dt with endless 
amount of defines. Furthermore I believe the benefits of these defines
would be negligible compared to effort maintaining defines and
documentation of them causes. Surely the one who needs to add dt node
for this chip in his board's dt has the manual for the chip he has on
board. Especially so if he knows the trickle charger there and wants to
configure it. The plain resistor type still gives zero information
without knowing the other details.

-- 
=============================================

Matti Vaittinen
Senile SW Specialist
FINLAND 

~~ When things go utterly wrong vim users can always type :help! ~~

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Mark Rutland]

On Fri, Aug 29, 2014 at 08:34:25AM +0100, Matti Vaittinen wrote:
> On Thu, Aug 28, 2014 at 10:40:34AM -0700, ext Guenter Roeck wrote:
> > On Thu, Aug 28, 2014 at 01:28:42PM -0400, Jason Cooper wrote:
> > > On Thu, Aug 28, 2014 at 09:48:25AM -0700, Guenter Roeck wrote:
> > > > On Thu, Aug 28, 2014 at 05:10:25PM +0100, Mark Rutland wrote:
> > > > > On Thu, Aug 28, 2014 at 04:51:57PM +0100, Guenter Roeck wrote:
> > > > > > On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> > > > > > > On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > > > > > > > Patch adding support for specifying trickle charger setup from device
> > > > > > > > tree. Patch is based on linux-next tree.
> > > > > > > > 
> > > > > > > > 
> > > > > > > > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > > > > > > > for specifying the setup and register values.
> > > > > > > > 
> > > > > > > > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > > > > @@ -0,0 +1,19 @@
> > > > > > > > +* Dallas DS1339		I2C Serial Real-Time Clock
> > > > > > > > +
> > > > > > > > +Required properties:
> > > > > > > > +- compatible: Should contain "dallas,ds1339".
> > > > > > > > +- reg: I2C address for chip
> > > > > > > > +
> > > > > > > > +Optional properties:
> > > > > > > > +- trickle_setup : Used Trickle Charger configuration,
> > > > > > > > +        corresponding to 5 lowest bits in trickle charger register.
> > > > > > > 
> > > > > > The value is provided via platform data, so it is platform specific
> > > > > > and presumably needs to be configurable. I did, however, not find
> > > > > > a single in-kernel driver which is actually setting it.
> > > > > > So this is a good question.
> > > > > 
> > > > > I'm uncomfortable adding a field we don't understand to DT.
> > > > > 
> > > > > Is there any publicly-available documentation for the device?
> > > > > 
> > > > 
> > > > Lots ;-)
> > > > 
> > > > http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> > > > http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> > > > http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> > > > http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> > > > http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> > > > http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> > > > http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
> > > > 
> > > > Code suggests that DS1339, DS1339, and DS1340 have the register.
> > > > 
> > > > Looking into the datasheets, the configuration consists of two parts:
> > > > - diode connected or not
> > > > - trickle charger resistor value (250, 2000, or 4000 ohm)
> > > > 
> > > > Given that, it seems to me that those values should be configured
> > > > explicitly instead of using a binary value, and that the driver
> > > > should perform the conversion from dt entry to register value.
> > > 
> > > iiuc, there is no way for the kernel to determine what is being trickle
> > > charged, and thus no way to determine how it should set this register.
> > > 
> > > It may be a bit of overkill, but I think a DT macro would be the most
> > > maintainable solution here:
> > > 
> > > #define DS1339_TRCKL_DIODE   0x08
> > > #define DS1339_TRCKL_NODIODE 0x04
> > > #define DS1339_TRCKL_R250    0x01
> > > #define DS1339_TRCKL_R2000   0x02
> > > #define DS1339_TRCKL_R4000   0x03
> > > 
> > > trickle_setup = <DS1339_TRCKL_DIODE | DS1339_TRCKL_R250>;
> > > 
> > > And the driver would take care of oring it with the enable pattern.
> > > 
> > 
> > Yes, that sounds reasonable as well.
> > 
> I thought of this too. However the ds1307 seems to be designed to work
> with bunch of chips. What then when next chip supported by this driver
> introduces 75, 1000 and 5000 ohm resistors? Or something else. (Or add
> some other configuration). I do not see this approach to be
> maintainable in long run.

If a new chip comes out with new features, the driver will need an
update anyhow. We have no guarantee that the register placement will be
the same, let alone the layout.

If and when said new chip comes out we allocate a new compatible string.
If it's compatible iwith (i.e. is a superset of) an existing device's
programming model, we add that existing string as a fallback in the
compatible list so old kernels can drive the subset of features they
understand.

> I see strong possibility of polluting dt with endless amount of
> defines. Furthermore I believe the benefits of these defines would be
> negligible compared to effort maintaining defines and documentation of
> them causes. Surely the one who needs to add dt node for this chip in
> his board's dt has the manual for the chip he has on board. Especially
> so if he knows the trickle charger there and wants to configure it.
> The plain resistor type still gives zero information without knowing
> the other details.

I would rather that the driver had some idea of what it were doing
rather than being a glorified copy routine.

I would suggest we have two properties that describe the resistor's
rating and whether or not there is a diode:

trickle-resistor-ohms = <250>
diode-connected;

That's easy for a human to write and/or validate, we can easily extend
it in future, requires no proliferation of macros, and describes the
hardware rather than telling software what to do.

The driver becomes a little more complicated, but gains sanity checking,
which is a good thing.

I'm still worried that we have no idea what the device is intended to
charge. Surely that's important?

Thanks,
Mark.

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Matti Vaittinen]

On Fri, Aug 29, 2014 at 11:40:02AM +0100, ext Mark Rutland wrote:
> On Fri, Aug 29, 2014 at 08:34:25AM +0100, Matti Vaittinen wrote:
> > On Thu, Aug 28, 2014 at 10:40:34AM -0700, ext Guenter Roeck wrote:
> > > On Thu, Aug 28, 2014 at 01:28:42PM -0400, Jason Cooper wrote:
> > > > On Thu, Aug 28, 2014 at 09:48:25AM -0700, Guenter Roeck wrote:
> > > > 
> > > > It may be a bit of overkill, but I think a DT macro would be the most
> > > > maintainable solution here:
> > > > 
> > > > #define DS1339_TRCKL_DIODE   0x08
> > > > #define DS1339_TRCKL_NODIODE 0x04
> > > > #define DS1339_TRCKL_R250    0x01
> > > > #define DS1339_TRCKL_R2000   0x02
> > > > #define DS1339_TRCKL_R4000   0x03
> > > > 
> > > > trickle_setup = <DS1339_TRCKL_DIODE | DS1339_TRCKL_R250>;
> > > > 
> > > > And the driver would take care of oring it with the enable pattern.
> > > > 
> > > 
> > > Yes, that sounds reasonable as well.
> > > 
> > I thought of this too. However the ds1307 seems to be designed to work
> > with bunch of chips. What then when next chip supported by this driver
> > introduces 75, 1000 and 5000 ohm resistors? Or something else. (Or add
> > some other configuration). I do not see this approach to be
> > maintainable in long run.
> 
> If a new chip comes out with new features, the driver will need an
> update anyhow. We have no guarantee that the register placement will be
> the same, let alone the layout.

This is why I originally also added the trickle_reg property. But let's
leave it out.

> 
> If and when said new chip comes out we allocate a new compatible string.
> If it's compatible iwith (i.e. is a superset of) an existing device's
> programming model, we add that existing string as a fallback in the
> compatible list so old kernels can drive the subset of features they
> understand.

Yes.

> 
> > I see strong possibility of polluting dt with endless amount of
> > defines. Furthermore I believe the benefits of these defines would be
> > negligible compared to effort maintaining defines and documentation of
> > them causes. Surely the one who needs to add dt node for this chip in
> > his board's dt has the manual for the chip he has on board. Especially
> > so if he knows the trickle charger there and wants to configure it.
> > The plain resistor type still gives zero information without knowing
> > the other details.
> 
> I would rather that the driver had some idea of what it were doing
> rather than being a glorified copy routine.
> 
> I would suggest we have two properties that describe the resistor's
> rating and whether or not there is a diode:
> 
> trickle-resistor-ohms = <250>
> diode-connected;
> 
> That's easy for a human to write and/or validate, we can easily extend
> it in future, requires no proliferation of macros, and describes the
> hardware rather than telling software what to do.
> 
> The driver becomes a little more complicated, but gains sanity checking,
> which is a good thing.

This looks like a nice way. Problem is that I can not provide support for 
all chips ds1307 supports. I have access to ds1339 variant only. I assume
the driver should thus reject this dt information for all other chips for 
now.

> 
> I'm still worried that we have no idea what the device is intended to
> charge. Surely that's important?

In my case it will charge capcitor which provides Vbackup for short
power breaks.

Br.
--Matti Vaittinen


-- 
=============================================

Matti Vaittinen
Senile SW Specialist
FINLAND 

~~ When things go utterly wrong vim users can always type :help! ~~

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Jason Cooper]

On Fri, Aug 29, 2014 at 11:40:02AM +0100, Mark Rutland wrote:
> On Fri, Aug 29, 2014 at 08:34:25AM +0100, Matti Vaittinen wrote:
> > On Thu, Aug 28, 2014 at 10:40:34AM -0700, ext Guenter Roeck wrote:
> > > On Thu, Aug 28, 2014 at 01:28:42PM -0400, Jason Cooper wrote:
> > > > On Thu, Aug 28, 2014 at 09:48:25AM -0700, Guenter Roeck wrote:
> > > > > On Thu, Aug 28, 2014 at 05:10:25PM +0100, Mark Rutland wrote:
> > > > > > On Thu, Aug 28, 2014 at 04:51:57PM +0100, Guenter Roeck wrote:
> > > > > > > On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> > > > > > > > On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > > > > > > > > Patch adding support for specifying trickle charger setup from device
> > > > > > > > > tree. Patch is based on linux-next tree.
> > > > > > > > > 
> > > > > > > > > 
> > > > > > > > > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > > > > > > > > for specifying the setup and register values.
> > > > > > > > > 
> > > > > > > > > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > > > > > @@ -0,0 +1,19 @@
> > > > > > > > > +* Dallas DS1339		I2C Serial Real-Time Clock
> > > > > > > > > +
> > > > > > > > > +Required properties:
> > > > > > > > > +- compatible: Should contain "dallas,ds1339".
> > > > > > > > > +- reg: I2C address for chip
> > > > > > > > > +
> > > > > > > > > +Optional properties:
> > > > > > > > > +- trickle_setup : Used Trickle Charger configuration,
> > > > > > > > > +        corresponding to 5 lowest bits in trickle charger register.
> > > > > > > > 
> > > > > > > The value is provided via platform data, so it is platform specific
> > > > > > > and presumably needs to be configurable. I did, however, not find
> > > > > > > a single in-kernel driver which is actually setting it.
> > > > > > > So this is a good question.
> > > > > > 
> > > > > > I'm uncomfortable adding a field we don't understand to DT.
> > > > > > 
> > > > > > Is there any publicly-available documentation for the device?
> > > > > > 
> > > > > 
> > > > > Lots ;-)
> > > > > 
> > > > > http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> > > > > http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> > > > > http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> > > > > http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> > > > > http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> > > > > http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> > > > > http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
> > > > > 
> > > > > Code suggests that DS1339, DS1339, and DS1340 have the register.
> > > > > 
> > > > > Looking into the datasheets, the configuration consists of two parts:
> > > > > - diode connected or not
> > > > > - trickle charger resistor value (250, 2000, or 4000 ohm)
> > > > > 
> > > > > Given that, it seems to me that those values should be configured
> > > > > explicitly instead of using a binary value, and that the driver
> > > > > should perform the conversion from dt entry to register value.
> > > > 
> > > > iiuc, there is no way for the kernel to determine what is being trickle
> > > > charged, and thus no way to determine how it should set this register.
> > > > 
> > > > It may be a bit of overkill, but I think a DT macro would be the most
> > > > maintainable solution here:
> > > > 
> > > > #define DS1339_TRCKL_DIODE   0x08
> > > > #define DS1339_TRCKL_NODIODE 0x04
> > > > #define DS1339_TRCKL_R250    0x01
> > > > #define DS1339_TRCKL_R2000   0x02
> > > > #define DS1339_TRCKL_R4000   0x03
> > > > 
> > > > trickle_setup = <DS1339_TRCKL_DIODE | DS1339_TRCKL_R250>;
> > > > 
> > > > And the driver would take care of oring it with the enable pattern.
> > > > 
> > > 
> > > Yes, that sounds reasonable as well.
> > > 
> > I thought of this too. However the ds1307 seems to be designed to work
> > with bunch of chips. What then when next chip supported by this driver
> > introduces 75, 1000 and 5000 ohm resistors? Or something else. (Or add
> > some other configuration). I do not see this approach to be
> > maintainable in long run.
> 
> If a new chip comes out with new features, the driver will need an
> update anyhow. We have no guarantee that the register placement will be
> the same, let alone the layout.

Yes, I'm reminded of our conversations a year ago in Edinburgh.  It's
impossible to engineer a perfect, future-proof binding.  But that
being said...

> If and when said new chip comes out we allocate a new compatible string.
> If it's compatible iwith (i.e. is a superset of) an existing device's
> programming model, we add that existing string as a fallback in the
> compatible list so old kernels can drive the subset of features they
> understand.
> 
> > I see strong possibility of polluting dt with endless amount of
> > defines. Furthermore I believe the benefits of these defines would be
> > negligible compared to effort maintaining defines and documentation of
> > them causes. Surely the one who needs to add dt node for this chip in
> > his board's dt has the manual for the chip he has on board. Especially
> > so if he knows the trickle charger there and wants to configure it.
> > The plain resistor type still gives zero information without knowing
> > the other details.
> 
> I would rather that the driver had some idea of what it were doing
> rather than being a glorified copy routine.
> 
> I would suggest we have two properties that describe the resistor's
> rating and whether or not there is a diode:
> 
> trickle-resistor-ohms = <250>
> diode-connected;

I much prefer this solution over my own suggestion.  With one small
change, s/diode-connected/trickle-diode-enable/  Does that sound ok?

> That's easy for a human to write and/or validate, we can easily extend
> it in future, requires no proliferation of macros, and describes the
> hardware rather than telling software what to do.
> 
> The driver becomes a little more complicated, but gains sanity checking,
> which is a good thing.
> 
> I'm still worried that we have no idea what the device is intended to
> charge. Surely that's important?

In the docs it said a variety of batteries and supercaps.  Yeah, not
much help...

thx,

Jason.

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Mark Rutland]

On Fri, Aug 29, 2014 at 01:24:52PM +0100, Jason Cooper wrote:
> On Fri, Aug 29, 2014 at 11:40:02AM +0100, Mark Rutland wrote:
> > On Fri, Aug 29, 2014 at 08:34:25AM +0100, Matti Vaittinen wrote:
> > > On Thu, Aug 28, 2014 at 10:40:34AM -0700, ext Guenter Roeck wrote:
> > > > On Thu, Aug 28, 2014 at 01:28:42PM -0400, Jason Cooper wrote:
> > > > > On Thu, Aug 28, 2014 at 09:48:25AM -0700, Guenter Roeck wrote:
> > > > > > On Thu, Aug 28, 2014 at 05:10:25PM +0100, Mark Rutland wrote:
> > > > > > > On Thu, Aug 28, 2014 at 04:51:57PM +0100, Guenter Roeck wrote:
> > > > > > > > On Thu, Aug 28, 2014 at 01:59:15PM +0100, Mark Rutland wrote:
> > > > > > > > > On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > > > > > > > > > Patch adding support for specifying trickle charger setup from device
> > > > > > > > > > tree. Patch is based on linux-next tree.
> > > > > > > > > > 
> > > > > > > > > > 
> > > > > > > > > > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > > > > > > > > > for specifying the setup and register values.
> > > > > > > > > > 
> > > > > > > > > > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > > > > > > > > > @@ -0,0 +1,19 @@
> > > > > > > > > > +* Dallas DS1339		I2C Serial Real-Time Clock
> > > > > > > > > > +
> > > > > > > > > > +Required properties:
> > > > > > > > > > +- compatible: Should contain "dallas,ds1339".
> > > > > > > > > > +- reg: I2C address for chip
> > > > > > > > > > +
> > > > > > > > > > +Optional properties:
> > > > > > > > > > +- trickle_setup : Used Trickle Charger configuration,
> > > > > > > > > > +        corresponding to 5 lowest bits in trickle charger register.
> > > > > > > > > 
> > > > > > > > The value is provided via platform data, so it is platform specific
> > > > > > > > and presumably needs to be configurable. I did, however, not find
> > > > > > > > a single in-kernel driver which is actually setting it.
> > > > > > > > So this is a good question.
> > > > > > > 
> > > > > > > I'm uncomfortable adding a field we don't understand to DT.
> > > > > > > 
> > > > > > > Is there any publicly-available documentation for the device?
> > > > > > > 
> > > > > > 
> > > > > > Lots ;-)
> > > > > > 
> > > > > > http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> > > > > > http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> > > > > > http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> > > > > > http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> > > > > > http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> > > > > > http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> > > > > > http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
> > > > > > 
> > > > > > Code suggests that DS1339, DS1339, and DS1340 have the register.
> > > > > > 
> > > > > > Looking into the datasheets, the configuration consists of two parts:
> > > > > > - diode connected or not
> > > > > > - trickle charger resistor value (250, 2000, or 4000 ohm)
> > > > > > 
> > > > > > Given that, it seems to me that those values should be configured
> > > > > > explicitly instead of using a binary value, and that the driver
> > > > > > should perform the conversion from dt entry to register value.
> > > > > 
> > > > > iiuc, there is no way for the kernel to determine what is being trickle
> > > > > charged, and thus no way to determine how it should set this register.
> > > > > 
> > > > > It may be a bit of overkill, but I think a DT macro would be the most
> > > > > maintainable solution here:
> > > > > 
> > > > > #define DS1339_TRCKL_DIODE   0x08
> > > > > #define DS1339_TRCKL_NODIODE 0x04
> > > > > #define DS1339_TRCKL_R250    0x01
> > > > > #define DS1339_TRCKL_R2000   0x02
> > > > > #define DS1339_TRCKL_R4000   0x03
> > > > > 
> > > > > trickle_setup = <DS1339_TRCKL_DIODE | DS1339_TRCKL_R250>;
> > > > > 
> > > > > And the driver would take care of oring it with the enable pattern.
> > > > > 
> > > > 
> > > > Yes, that sounds reasonable as well.
> > > > 
> > > I thought of this too. However the ds1307 seems to be designed to work
> > > with bunch of chips. What then when next chip supported by this driver
> > > introduces 75, 1000 and 5000 ohm resistors? Or something else. (Or add
> > > some other configuration). I do not see this approach to be
> > > maintainable in long run.
> > 
> > If a new chip comes out with new features, the driver will need an
> > update anyhow. We have no guarantee that the register placement will be
> > the same, let alone the layout.
> 
> Yes, I'm reminded of our conversations a year ago in Edinburgh.  It's
> impossible to engineer a perfect, future-proof binding.  But that
> being said...
> 
> > If and when said new chip comes out we allocate a new compatible string.
> > If it's compatible iwith (i.e. is a superset of) an existing device's
> > programming model, we add that existing string as a fallback in the
> > compatible list so old kernels can drive the subset of features they
> > understand.
> > 
> > > I see strong possibility of polluting dt with endless amount of
> > > defines. Furthermore I believe the benefits of these defines would be
> > > negligible compared to effort maintaining defines and documentation of
> > > them causes. Surely the one who needs to add dt node for this chip in
> > > his board's dt has the manual for the chip he has on board. Especially
> > > so if he knows the trickle charger there and wants to configure it.
> > > The plain resistor type still gives zero information without knowing
> > > the other details.
> > 
> > I would rather that the driver had some idea of what it were doing
> > rather than being a glorified copy routine.
> > 
> > I would suggest we have two properties that describe the resistor's
> > rating and whether or not there is a diode:
> > 
> > trickle-resistor-ohms = <250>
> > diode-connected;
> 
> I much prefer this solution over my own suggestion.  With one small
> change, s/diode-connected/trickle-diode-enable/  Does that sound ok?

I'm not too keen on 'enable'; I was under the impression that this
described whether or not there was an external diode. Perhaps I've
misunderstood?

Thanks,
Mark.

> > That's easy for a human to write and/or validate, we can easily extend
> > it in future, requires no proliferation of macros, and describes the
> > hardware rather than telling software what to do.
> > 
> > The driver becomes a little more complicated, but gains sanity checking,
> > which is a good thing.
> > 
> > I'm still worried that we have no idea what the device is intended to
> > charge. Surely that's important?
> 
> In the docs it said a variety of batteries and supercaps.  Yeah, not
> much help...
> 
> thx,
> 
> Jason.
> 

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Jason Cooper]

On Fri, Aug 29, 2014 at 01:42:16PM +0100, Mark Rutland wrote:
> On Fri, Aug 29, 2014 at 01:24:52PM +0100, Jason Cooper wrote:
> > On Fri, Aug 29, 2014 at 11:40:02AM +0100, Mark Rutland wrote:
...
Someone wrote:
> > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> > > > > > > http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
...
> > > I would suggest we have two properties that describe the resistor's
> > > rating and whether or not there is a diode:
> > > 
> > > trickle-resistor-ohms = <250>
> > > diode-connected;
> > 
> > I much prefer this solution over my own suggestion.  With one small
> > change, s/diode-connected/trickle-diode-enable/  Does that sound ok?
> 
> I'm not too keen on 'enable'; I was under the impression that this
> described whether or not there was an external diode. Perhaps I've
> misunderstood?

iiuc from the link ds1339 ds, the register configuration is enabling
internal diodes and resistors for the trickle charge configuration.  I
may have read it incorrectly, though.

In either case, my main point was to prepend 'trickle-' to the property
to more accurately describe what it is toggling.

thx,

Jason.

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Mark Rutland]

On Fri, Aug 29, 2014 at 01:48:29PM +0100, Jason Cooper wrote:
> On Fri, Aug 29, 2014 at 01:42:16PM +0100, Mark Rutland wrote:
> > On Fri, Aug 29, 2014 at 01:24:52PM +0100, Jason Cooper wrote:
> > > On Fri, Aug 29, 2014 at 11:40:02AM +0100, Mark Rutland wrote:
> ...
> Someone wrote:
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
> ...
> > > > I would suggest we have two properties that describe the resistor's
> > > > rating and whether or not there is a diode:
> > > > 
> > > > trickle-resistor-ohms = <250>
> > > > diode-connected;
> > > 
> > > I much prefer this solution over my own suggestion.  With one small
> > > change, s/diode-connected/trickle-diode-enable/  Does that sound ok?
> > 
> > I'm not too keen on 'enable'; I was under the impression that this
> > described whether or not there was an external diode. Perhaps I've
> > misunderstood?
> 
> iiuc from the link ds1339 ds, the register configuration is enabling
> internal diodes and resistors for the trickle charge configuration.  I
> may have read it incorrectly, though.

Ok.

> In either case, my main point was to prepend 'trickle-' to the property
> to more accurately describe what it is toggling.

That's fine by me. My only concern was 'enable' due to the
internal/external confusion.

Thanks,
Mark.

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Matti Vaittinen]

On Fri, Aug 29, 2014 at 08:48:29AM -0400, ext Jason Cooper wrote:
> On Fri, Aug 29, 2014 at 01:42:16PM +0100, Mark Rutland wrote:
> > On Fri, Aug 29, 2014 at 01:24:52PM +0100, Jason Cooper wrote:
> > > On Fri, Aug 29, 2014 at 11:40:02AM +0100, Mark Rutland wrote:
> ...
> Someone wrote:
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1307.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1337.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1338.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1339.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1340.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS1388.pdf
> > > > > > > > http://datasheets.maximintegrated.com/en/ds/DS3231.pdf
> ...
> > > > I would suggest we have two properties that describe the resistor's
> > > > rating and whether or not there is a diode:
> > > > 
> > > > trickle-resistor-ohms = <250>
> > > > diode-connected;
> > > 
> > > I much prefer this solution over my own suggestion.  With one small
> > > change, s/diode-connected/trickle-diode-enable/  Does that sound ok?
> > 
> > I'm not too keen on 'enable'; I was under the impression that this
> > described whether or not there was an external diode. Perhaps I've
> > misunderstood?
> 
> iiuc from the link ds1339 ds, the register configuration is enabling
> internal diodes and resistors for the trickle charge configuration.  I
> may have read it incorrectly, though.

Yes. It is about using internal diode.

I will cook new patch based on these comments on monday.

Regards
  Matti Vaittinen

-- 
=============================================

Matti Vaittinen
Senile SW Specialist
FINLAND 

~~ When things go utterly wrong vim users can always type :help! ~~

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Pavel Machek]

Hi!

> I would suggest we have two properties that describe the resistor's
> rating and whether or not there is a diode:
> 
> trickle-resistor-ohms = <250>
> diode-connected;
> 
> That's easy for a human to write and/or validate, we can easily extend
> it in future, requires no proliferation of macros, and describes the
> hardware rather than telling software what to do.
> 
> The driver becomes a little more complicated, but gains sanity checking,
> which is a good thing.

Certainly looks better than register bit defines.

As rtc-bq32k has similar options, I'm interested, too. I believe we
should add

trickle-charge-enable;

(we may not want to charge at all), and I believe the diode should be

disconnect-diode;

... With diode connected, charge is slower, and that probably should
be the default value. We don't want to give too much current in
default case.  (bq32k has hard-coded resistor value for
diode/not-diode case).

Thanks and best regards,
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Mark Rutland]

On Mon, Sep 08, 2014 at 02:52:42PM +0100, Pavel Machek wrote:
> Hi!
> 
> > I would suggest we have two properties that describe the resistor's
> > rating and whether or not there is a diode:
> > 
> > trickle-resistor-ohms = <250>
> > diode-connected;
> > 
> > That's easy for a human to write and/or validate, we can easily extend
> > it in future, requires no proliferation of macros, and describes the
> > hardware rather than telling software what to do.
> > 
> > The driver becomes a little more complicated, but gains sanity checking,
> > which is a good thing.
> 
> Certainly looks better than register bit defines.
> 
> As rtc-bq32k has similar options, I'm interested, too. I believe we
> should add
> 
> trickle-charge-enable;
> 
> (we may not want to charge at all), and I believe the diode should be
> 
> disconnect-diode;
> 
> ... With diode connected, charge is slower, and that probably should
> be the default value. We don't want to give too much current in
> default case.  (bq32k has hard-coded resistor value for
> diode/not-diode case).

I agree that if one case is less likely to be problematic / damaging
that should be the default.

Mark.

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Matti Vaittinen]

On Mon, Sep 08, 2014 at 03:58:25PM +0100, ext Mark Rutland wrote:
> On Mon, Sep 08, 2014 at 02:52:42PM +0100, Pavel Machek wrote:
> > > I would suggest we have two properties that describe the resistor's
> > > rating and whether or not there is a diode:
> > > 
> > > trickle-resistor-ohms = <250>
> > > diode-connected;
> > > 
> > > That's easy for a human to write and/or validate, we can easily extend
> > > it in future, requires no proliferation of macros, and describes the
> > > hardware rather than telling software what to do.
> > > 
> > > The driver becomes a little more complicated, but gains sanity checking,
> > > which is a good thing.
> > 
> > Certainly looks better than register bit defines.
> > 
> > As rtc-bq32k has similar options, I'm interested, too. I believe we
> > should add
> > 
> > trickle-charge-enable;

I am unsure about this. It makes sense for devices where we cannot
select resistor but just enable or disable charger. Is there any such
devices? For devices like ds1339 this makes no sense. For them it is
simpler to just enable the charger if resistor value is specified, and
default the charger to be off. But I do not see a problem in supporting
the trickle-charge-enable; for devices needing this (independently from
the ds1307 driver).

> > 
> > (we may not want to charge at all), and I believe the diode should be
> > 
> > disconnect-diode;
> > 
> > ... With diode connected, charge is slower, and that probably should
> > be the default value. We don't want to give too much current in
> > default case.  (bq32k has hard-coded resistor value for
> > diode/not-diode case).
> 
> I agree that if one case is less likely to be problematic / damaging
> that should be the default.

_Maybe_ 
diode-connected = <1>; or 
diode-connected = <0>; 
or both
diode-connected; and 
diode-disconnected;
could be used and let the driver to choose the defaults? But yes, I have
no problem with inverting the default to be diode-connected.

Then one question regarding the "process". Now if I cook up fourth patch
with inverted diode-connected default for ds1339, should I collect new
acks for this new patch? (V3 was acked by Alessandro and Jason.) I assume 
yes.

> 
> Mark.

-- 
=============================================

Matti Vaittinen
Senile SW Specialist
FINLAND 

~~ When things go utterly wrong vim users can always type :help! ~~

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Pavel Machek]

Hi!

> > > > trickle-resistor-ohms = <250>
> > > > diode-connected;
> > > > 
> > > > That's easy for a human to write and/or validate, we can easily extend
> > > > it in future, requires no proliferation of macros, and describes the
> > > > hardware rather than telling software what to do.
> > > > 
> > > > The driver becomes a little more complicated, but gains sanity checking,
> > > > which is a good thing.
> > > 
> > > Certainly looks better than register bit defines.
> > > 
> > > As rtc-bq32k has similar options, I'm interested, too. I believe we
> > > should add
> > > 
> > > trickle-charge-enable;
> 
> I am unsure about this. It makes sense for devices where we cannot
> select resistor but just enable or disable charger. Is there any such
> devices? For devices like ds1339 this makes no sense. For them it is
> simpler to just enable the charger if resistor value is specified, and
> default the charger to be off. But I do not see a problem in supporting
> the trickle-charge-enable; for devices needing this (independently from
> the ds1307 driver).

Ok, just cc me on next version of the driver, and I'll adjust bq32k to
be similar.

> > > (we may not want to charge at all), and I believe the diode should be
> > > 
> > > disconnect-diode;
> > > 
> > > ... With diode connected, charge is slower, and that probably should
> > > be the default value. We don't want to give too much current in
> > > default case.  (bq32k has hard-coded resistor value for
> > > diode/not-diode case).
> > 
> > I agree that if one case is less likely to be problematic / damaging
> > that should be the default.
> 
> _Maybe_ 
> diode-connected = <1>; or 
> diode-connected = <0>; 

That should work.

Actually, make it "connect-diode = <0/1>;", because hardware can
actually select if the diode is connected or not.

> Then one question regarding the "process". Now if I cook up fourth patch
> with inverted diode-connected default for ds1339, should I collect new
> acks for this new patch? (V3 was acked by Alessandro and Jason.) I assume 
> yes.

It depends if patch changed "a lot". I guess you can keep the acks.

								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Jason Cooper]

On Tue, Sep 09, 2014 at 01:34:25PM +0200, Pavel Machek wrote:
...
> > _Maybe_ 
> > diode-connected = <1>; or 
> > diode-connected = <0>; 
> 
> That should work.

meh.  The presence or absence of the property should express the
boolean.

The safe state should be the default (property absent), and the property
name should describe the state when the property is present.

thx,

Jason.

VS: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Vaittinen, Matti (NSN - FI/Oulu)]

Lähettäjä: ext Jason Cooper 

> meh.  The presence or absence of the property should express the
boolean.
> 
> The safe state should be the default (property absent), and the property
name should describe the state when the property is present.

This is What the v5 of patch does. It introduces boolean flag trickle-diode-disable. Diode enabled should be safer and it is also the default.
Jason, I added your ack to that patch, thanks.

Br. Matti Vaittinen 

Re: [PATCH] rtc: ds1307: add trickle charger device tree binding

[Matti Vaittinen]

On Thu, Aug 28, 2014 at 01:59:15PM +0100, ext Mark Rutland wrote:
> On Thu, Aug 28, 2014 at 01:42:44PM +0100, Matti Vaittinen wrote:
> > Patch adding support for specifying trickle charger setup from device
> > tree. Patch is based on linux-next tree.
> > 
> > 
> > Some DS13XX devices have "trickle chargers". Introduce a device tree binding
> > for specifying the setup and register values.
> > 
> > diff --git a/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > new file mode 100644
> > index 0000000..9faf40e
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/rtc/dallas,ds1339.txt
> > @@ -0,0 +1,19 @@
> > +* Dallas DS1339		I2C Serial Real-Time Clock
> > +
> > +Required properties:
> > +- compatible: Should contain "dallas,ds1339".
> > +- reg: I2C address for chip
> > +
> > +Optional properties:
> > +- trickle_setup : Used Trickle Charger configuration,
> > +        corresponding to 5 lowest bits in trickle charger register.
> 
> s/_/-/ in property names please.
I'll fix this, thanks.

> Why do we not have a higher-level description?
I can add the meanings for this specific chip in the binding document,
  however I would still keep the raw register value as the dt entry due
  to reasons explained in my previous email.
> 
> > +- trickle_reg   : Trickle charger register address. Defaults to 0x10 for ds1339.
> 
> Is this expected to change? Why does this need to be in the DT?

I was thinking it might be handly as I do not know the details of all
variants of this chip. However I guess it could be left out.

> 
> > +
> > +Example:
> > +	ds1339: rtc@68 {
> > +		compatible = "dallas,ds1339";
> > +        trickle_setup= <0x5>;
> > +		reg = <0x68>;
> > +	};
> > +
> > +
> > diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> > index f03d5ba..f9b1244 100644
> > --- a/drivers/rtc/rtc-ds1307.c
> > +++ b/drivers/rtc/rtc-ds1307.c
> > @@ -126,9 +126,10 @@ struct chip_desc {
> >  	u16			nvram_offset;
> >  	u16			nvram_size;
> >  	u16			trickle_charger_reg;
> > +	u8		  trickle_charger_setup;
> >  };
> >  
> > -static const struct chip_desc chips[last_ds_type] = {
> > +static struct chip_desc chips[last_ds_type] = {
> >  	[ds_1307] = {
> >  		.nvram_offset	= 8,
> >  		.nvram_size	= 56,
> > @@ -835,13 +836,37 @@ ds1307_nvram_write(struct file *filp, struct kobject *kobj,
> >  
> >  /*----------------------------------------------------------------------*/
> >  
> > +static void trickle_charger_of_init(struct chip_desc *chip,
> > +			struct device_node *node)
> > +{
> > +	int plen = 0;
> > +	const uint32_t *setup;
> > +	const uint32_t *reg;
> > +
> > +	setup = of_get_property(node, "trickle_setup" , &plen);
> > +	if (plen != 4)
> > +		goto out;
> > +	chip->trickle_charger_setup = (u8)*setup;
> 
> This isn't endian-clean, and the casting is unnecessary.
> 
> Use the of_property_read_u32 accessor, with a u32 temporary variable.

I'll fix this, thanks.

> 
> > +	plen = 0;
> > +	reg = of_get_property(node, "trickle_reg" , &plen);
> > +	if (plen == 4)
> > +		chip->trickle_charger_reg = (u16)*reg;
> 
> Likewise.
> 
I'll drop the register address from dt alltogether.


I will fix these issues and prepare a new patch.

Br. Matti Vaittinen


-- 
=============================================

Matti Vaittinen
Senile SW Specialist
FINLAND 

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