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

Mark Rutland
2014-08-28T13:00:26Z

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.