Re: [PATCH v5 4/4] pmbus: ltc2978: add regulator support

[Guenter Roeck]

On 10/02/2014 11:37 AM, atull@xxxxxxxxxxxxxxxxxxxxx wrote:
> From: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
>
> Add simple on/off regulator support for ltc2978 and
> other pmbus parts supported by ltc2978.c
>
> Signed-off-by: Alan Tull <atull@xxxxxxxxxxxxxxxxxxxxx>
> ---
> v2: Remove '#include <linux/regulator/machine.h>'
>      Only one regulator per pmbus device
>      Get regulator_init_data from pdata or device tree
>
> v3: Support multiple regulators for each chip
>      Move most code to pmbus_core.c
>      fixed values for on/off
>
> v4: fix a #endif comment
>      simplify probe code, remove added switch statement
>      remove BUG_ON(), add error message and fix num_regulators
>
> v5: Kconfig: update list of supported chips
>      use "regulator: of: Provide simplified DT parsing method"
>      remove #include <linux/regulator/of_regulator.h>
>      remove of_regulator_match
> ---
>   drivers/hwmon/pmbus/Kconfig   |   11 +++++++++--
>   drivers/hwmon/pmbus/ltc2978.c |   24 ++++++++++++++++++++++++
>   2 files changed, 33 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/pmbus/Kconfig b/drivers/hwmon/pmbus/Kconfig
> index 6e1e493..a674cd8 100644
> --- a/drivers/hwmon/pmbus/Kconfig
> +++ b/drivers/hwmon/pmbus/Kconfig
> @@ -47,15 +47,22 @@ config SENSORS_LM25066
>   	  be called lm25066.
>
>   config SENSORS_LTC2978
> -	tristate "Linear Technologies LTC2974, LTC2978, LTC3880, and LTC3883"
> +	tristate "Linear Technologies LTC2978 and compatibles"
>   	default n
>   	help
>   	  If you say yes here you get hardware monitoring support for Linear
> -	  Technology LTC2974, LTC2978, LTC3880, and LTC3883.
> +	  Technology LTC2974, LTC2977, LTC2978, LTC3880, LTC3883, and LTM4676.
>
>   	  This driver can also be built as a module. If so, the module will
>   	  be called ltc2978.
>
> +config SENSORS_LTC2978_REGULATOR
> +	boolean "Regulator support for LTC2978 and compatibles"
> +	depends on SENSORS_LTC2978 && REGULATOR
> +	help
> +	  If you say yes here you get regulator support for Linear
> +	  Technology LTC2974, LTC2977, LTC2978, LTC3880, LTC3883, and LTM4676.
> +
>   config SENSORS_MAX16064
>   	tristate "Maxim MAX16064"
>   	default n
> diff --git a/drivers/hwmon/pmbus/ltc2978.c b/drivers/hwmon/pmbus/ltc2978.c
> index e24ed52..efac4bf 100644
> --- a/drivers/hwmon/pmbus/ltc2978.c
> +++ b/drivers/hwmon/pmbus/ltc2978.c
> @@ -22,6 +22,7 @@
>   #include <linux/err.h>
>   #include <linux/slab.h>
>   #include <linux/i2c.h>
> +#include <linux/regulator/driver.h>
>   #include "pmbus.h"
>
>   enum chips { ltc2974, ltc2977, ltc2978, ltc3880, ltc3883, ltm4676 };
> @@ -374,6 +375,19 @@ static const struct i2c_device_id ltc2978_id[] = {
>   };
>   MODULE_DEVICE_TABLE(i2c, ltc2978_id);
>
> +#if IS_ENABLED(CONFIG_SENSORS_LTC2978_REGULATOR)
> +static const struct regulator_desc ltc2978_reg_desc[] = {
> +	PMBUS_REGULATOR("vout_en", 0),
> +	PMBUS_REGULATOR("vout_en", 1),
> +	PMBUS_REGULATOR("vout_en", 2),
> +	PMBUS_REGULATOR("vout_en", 3),
> +	PMBUS_REGULATOR("vout_en", 4),
> +	PMBUS_REGULATOR("vout_en", 5),
> +	PMBUS_REGULATOR("vout_en", 6),
> +	PMBUS_REGULATOR("vout_en", 7),
> +};
> +#endif /* CONFIG_SENSORS_LTC2978_REGULATOR */
> +
>   static int ltc2978_probe(struct i2c_client *client,
>   			 const struct i2c_device_id *id)
>   {
> @@ -487,6 +501,16 @@ static int ltc2978_probe(struct i2c_client *client,
>   	default:
>   		return -ENODEV;
>   	}
> +
> +#if IS_ENABLED(CONFIG_SENSORS_LTC2978_REGULATOR)
> +	info->num_regulators = info->pages;
> +	info->reg_desc = ltc2978_reg_desc;
> +	if (info->num_regulators > ARRAY_SIZE(ltc2978_reg_desc)) {
> +		dev_err(&client->dev, "num_regulators too large!");
> +		info->num_regulators = ARRAY_SIZE(ltc2978_reg_desc);
> +	}
> +#endif
> +
>   	return pmbus_do_probe(client, id, info);
>   }

Unfortunately the code now only compiles in -next, since the following
fields are only defined there.

drivers/hwmon/pmbus/ltc2978.c:380:2: error: unknown field 'of_match' specified in initializer
drivers/hwmon/pmbus/ltc2978.c:380:2: error: unknown field 'regulators_node' specified in initializer

This means I can not apply the code unless I pull in the relevant changes.
Mark, do you have an immutable branch / tag for me to merge ?

If not this patch series will have to wait until the relevant regulator
changes are available in mainline.

On a side note, I am not too happy with the following comment in the
"Provide simplified DT parsing method" patch: "The current code leaks
the phandles for the child nodes, this will be addressed incrementally
and makes no practical difference for FDT anyway as the DT data
structures are never freed".

My use case includes instantiating the LTC chips through devicetree overlays,
which obviously does not work well with leaking DT nodes.

Thanks,
Guenter

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