linux-kernel - Re: [PATCH 3/6] mfd: stmpe: prope properly from the device tree

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Message-ID: <20140417104409.GL28725@lee--X1>
Date:	Thu, 17 Apr 2014 11:44:09 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Samuel Ortiz <sameo@...ux.intel.com>, linux-kernel@...r.kernel.org,
	Silvio F <silvio.fricke@...il.com>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Shawn Guo <shawn.guo@...aro.org>,
	Viresh Kumar <viresh.linux@...il.com>,
	Shiraz Hashim <shiraz.hashim@...com>, spear-devel@...t.st.com
Subject: Re: [PATCH 3/6] mfd: stmpe: prope properly from the device tree

> The current STMPE I2C probing code does not really match the
> compatible strings - it matches node names happening to give
> the right device name. Instead, let's introduce some real
> compatible matching, more complex, more accurate.
> 
> Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
> ---
>  drivers/mfd/stmpe-i2c.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 59 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/stmpe-i2c.c b/drivers/mfd/stmpe-i2c.c
> index 0da02e11d58e..8902a600d978 100644
> --- a/drivers/mfd/stmpe-i2c.c
> +++ b/drivers/mfd/stmpe-i2c.c
> @@ -14,6 +14,7 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/types.h>
> +#include <linux/of_device.h>
>  #include "stmpe.h"
>  
>  static int i2c_reg_read(struct stmpe *stmpe, u8 reg)
> @@ -52,15 +53,71 @@ static struct stmpe_client_info i2c_ci = {
>  	.write_block = i2c_block_write,
>  };
>  
> +#ifdef CONFIG_OF

Didn't you say that the only platform using this device is DT only? So
why don't we make the driver depend on OF and get rid of this ugly
#ifdeffery?

> +static const struct of_device_id stmpe_of_match[] = {
> +	{
> +		.compatible = "st,stmpe610",
> +		.data = (void *)STMPE610,
> +	},
> +	{
> +		.compatible = "st,stmpe801",
> +		.data = (void *)STMPE801,
> +	},
> +	{
> +		.compatible = "st,stmpe811",
> +		.data = (void *)STMPE811,
> +	},
> +	{
> +		.compatible = "st,stmpe1601",
> +		.data = (void *)STMPE1601,
> +	},
> +	{
> +		.compatible = "st,stmpe1801",
> +		.data = (void *)STMPE1801,
> +	},
> +	{
> +		.compatible = "st,stmpe2401",
> +		.data = (void *)STMPE2401,
> +	},
> +	{
> +		.compatible = "st,stmpe2403",
> +		.data = (void *)STMPE2403,
> +	},
> +	{},
> +};

If none of these stray over 80 chars, I think I'd like to see
of_device_id tables as single line entries (unlike mfd_cell structures
where there can be more than 2 entries, which I like spread out - I
know, double standards right?)

+static const struct of_device_id stmpe_of_match[] = {
+	{ .compatible = "st,stmpe610",  .data = (void *)STMPE610,  },
+	{ .compatible = "st,stmpe801",  .data = (void *)STMPE801,  },
+	{ .compatible = "st,stmpe811",  .data = (void *)STMPE811,  },
+	{ .compatible = "st,stmpe1601", .data = (void *)STMPE1601, },
+	{ .compatible = "st,stmpe1801", .data = (void *)STMPE1801, },
+	{ .compatible = "st,stmpe2401", .data = (void *)STMPE2401, },
+	{ .compatible = "st,stmpe2403", .data = (void *)STMPE2403, },
+	{},
+};

> +MODULE_DEVICE_TABLE(of, stmpe_of_match);
> +
> +int stmpe_i2c_of_probe(struct i2c_client *i2c)

Erm, static?

> +{
> +	const struct of_device_id *of_id;
> +
> +	of_id = of_match_device(stmpe_of_match, &i2c->dev);
> +	if (!of_id)
> +		return -EINVAL;
> +	return (int)of_id->data;
> +}
> +#else
> +int stmpe_i2c_of_probe(struct i2c_client *i2c)
> +{
> +	return -EINVAL;
> +}
> +#endif
> +
>  static int
>  stmpe_i2c_probe(struct i2c_client *i2c, const struct i2c_device_id *id)
>  {
> +	int partnum;
> +
>  	i2c_ci.data = (void *)id;
>  	i2c_ci.irq = i2c->irq;
>  	i2c_ci.client = i2c;
>  	i2c_ci.dev = &i2c->dev;
>  
> -	return stmpe_probe(&i2c_ci, id->driver_data);

if (IS_DEFINED(OF)) {

> +	partnum = stmpe_i2c_of_probe(i2c);

Then you can remove the spare stmpe_i2c_of_probe(), or better still
make the whole driver depend on OF.

> +	if (partnum < 0)
> +		partnum = id->driver_data;

Should this be able to fail and for us to still carry on?

Or are we then running on an unsupported device?

> +	return stmpe_probe(&i2c_ci, partnum);
>  }
>  
>  static int stmpe_i2c_remove(struct i2c_client *i2c)
> @@ -89,6 +146,7 @@ static struct i2c_driver stmpe_i2c_driver = {
>  #ifdef CONFIG_PM
>  		.pm = &stmpe_dev_pm_ops,
>  #endif
> +		.of_match_table = of_match_ptr(stmpe_of_match),
>  	},
>  	.probe		= stmpe_i2c_probe,
>  	.remove		= stmpe_i2c_remove,

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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