linux-kernel - Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device Tree

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Date:   Wed, 4 Jan 2017 11:54:24 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Richard Purdie <rpurdie@...ys.net>,
        Jacek Anaszewski <j.anaszewski@...sung.com>,
        Pavel Machek <pavel@....cz>, Jingoo Han <jingoohan1@...il.com>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-iio@...r.kernel.org, linux-leds@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...ymobile.com>
Subject: Re: [PATCH v4 2/5] mfd: lm3533: Support initialization from Device
 Tree

On Mon, 26 Dec 2016, Bjorn Andersson wrote:

> From: Bjorn Andersson <bjorn.andersson@...ymobile.com>
> 
> Implement support for initialization of the lm3533 driver core and
> probing child devices from Device Tree.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...ymobile.com>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
> 
> Changes since v3:
> - Moved parsing of child of nodes into each child driver
> - Use of_platform_populate() to instanciate child devices
> 
>  drivers/mfd/lm3533-core.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 76 insertions(+)
> 
> diff --git a/drivers/mfd/lm3533-core.c b/drivers/mfd/lm3533-core.c
> index 5abcbb2e8849..f147677f05ff 100644
> --- a/drivers/mfd/lm3533-core.c
> +++ b/drivers/mfd/lm3533-core.c
> @@ -18,6 +18,8 @@
>  #include <linux/gpio.h>
>  #include <linux/i2c.h>
>  #include <linux/mfd/core.h>
> +#include <linux/of_gpio.h>
> +#include <linux/of_platform.h>
>  #include <linux/regmap.h>
>  #include <linux/seq_file.h>
>  #include <linux/slab.h>
> @@ -512,6 +514,11 @@ static int lm3533_device_init(struct lm3533 *lm3533)
>  	lm3533_device_bl_init(lm3533);
>  	lm3533_device_led_init(lm3533);
>  
> +	if (lm3533->dev->of_node) {
> +		of_platform_populate(lm3533->dev->of_node, NULL, NULL,
> +				     lm3533->dev);
> +	}

I think it's save to call of_platform_populate(), even if !of_node.
It will just fail and return an error code, which you are ignoring
anyway.

>  	ret = sysfs_create_group(&lm3533->dev->kobj, &lm3533_attribute_group);
>  	if (ret < 0) {
>  		dev_err(lm3533->dev, "failed to create sysfs attributes\n");
> @@ -588,10 +595,73 @@ static const struct regmap_config regmap_config = {
>  	.precious_reg	= lm3533_precious_register,
>  };
>  
> +static int lm3533_of_parse_enum(struct device *dev, const char *propname,
> +				const unsigned int *match, size_t num_matches)
> +{
> +	size_t i;
> +	int ret;
> +	u32 val;
> +
> +	ret = of_property_read_u32(dev->of_node, propname, &val);
> +	if (ret < 0) {
> +		dev_err(dev, "failed to parse %s\n", propname);
> +		return ret;
> +	}
> +
> +	for (i = 0; i < num_matches; i++) {
> +		if (val == match[i])
> +			return i;
> +	}
> +
> +	dev_err(dev, "unsupported value of %s\n", propname);
> +	return -EINVAL;
> +}
> +
> +static int lm3533_pdata_from_of_node(struct device *dev)
> +{
> +	struct lm3533_platform_data *pdata;
> +	int ret;
> +	const unsigned int freqs[] = {
> +		[LM3533_BOOST_FREQ_500KHZ] = 500000,
> +		[LM3533_BOOST_FREQ_1000KHZ] = 1000000,
> +	};
> +	const unsigned int ovps[] = {
> +		[LM3533_BOOST_OVP_16V] = 16000,
> +		[LM3533_BOOST_OVP_24V] = 24000,
> +		[LM3533_BOOST_OVP_32V] = 32000,
> +		[LM3533_BOOST_OVP_40V] = 40000,
> +	};
> +
> +	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
> +	if (!pdata)
> +		return -ENOMEM;
> +
> +	pdata->gpio_hwen = of_get_named_gpio(dev->of_node, "hwen-gpios", 0);
> +	if (pdata->gpio_hwen < 0)
> +		return pdata->gpio_hwen;
> +
> +	ret = lm3533_of_parse_enum(dev, "ti,boost-freq-hz",
> +				   freqs, ARRAY_SIZE(freqs));
> +	if (ret < 0)
> +		return ret;
> +	pdata->boost_freq = ret;
> +
> +	ret = lm3533_of_parse_enum(dev, "ti,boost-ovp-mv",
> +				   ovps, ARRAY_SIZE(ovps));
> +	if (ret < 0)
> +		return ret;
> +	pdata->boost_ovp = ret;
> +
> +	dev->platform_data = pdata;
> +
> +	return 0;
> +}
> +
>  static int lm3533_i2c_probe(struct i2c_client *i2c,
>  					const struct i2c_device_id *id)
>  {
>  	struct lm3533 *lm3533;
> +	int ret;
>  
>  	dev_dbg(&i2c->dev, "%s\n", __func__);
>  
> @@ -608,6 +678,12 @@ static int lm3533_i2c_probe(struct i2c_client *i2c,
>  	lm3533->dev = &i2c->dev;
>  	lm3533->irq = i2c->irq;
>  
> +	if (i2c->dev.of_node) {

I'd prefer this check to be placed in lm3533_pdata_from_of_node().

Just return silently if !dev->of_node.

> +		ret = lm3533_pdata_from_of_node(lm3533->dev);
> +		if (ret < 0)
> +			return ret;
> +	}
> +
>  	return lm3533_device_init(lm3533);
>  }
>  

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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