Re: [PATCH] MFD AB3100 OTP readout

[Samuel Ortiz <sameo@linux.intel.com>]

Hi Linus,

On Mon, Aug 17, 2009 at 09:37:29AM +0200, Linus Walleij wrote:
> This adds the ability to read out OTP (One-Time Programmable)
> registers in the AB3100 MFD ASIC. It's a simple sysfs file you
> can cat to prompt. The OTP registers of the AB3100 are used to
> store various device-unique information such as customer ID,
> product flags and the 3GPP standard IMEI (International Mobile
> Equipment Indentity) number.
2 comments on this patch:

1) The sysfs rule of thumb is "1 value per file" (see
Documentation/filesystems/sysfs.txt". So if you want to use sysfs for that you
should split your register reads into several sysfs entries.
It seems to me that debugfs would be a more appropriate tool for what you're
trying to achieve.

2) You really dont need to register a new driver just for adding some sysfs or
debugfs entries. Your ab3100_otp_probe() routine could just be called by your
ab3100_probe routine, or added to the ab3100_setup_debugfs() one. 

Cheers,
Samuel.

> Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
> ---
>  drivers/mfd/Makefile     |    2 +-
>  drivers/mfd/ab3100-otp.c |  123 ++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 124 insertions(+), 1 deletions(-)
>  create mode 100644 drivers/mfd/ab3100-otp.c
> 
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 6f8a9a1..13128b4 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -43,4 +43,4 @@ obj-$(CONFIG_PMIC_DA903X)	+= da903x.o
>  obj-$(CONFIG_MFD_PCF50633)	+= pcf50633-core.o
>  obj-$(CONFIG_PCF50633_ADC)	+= pcf50633-adc.o
>  obj-$(CONFIG_PCF50633_GPIO)	+= pcf50633-gpio.o
> -obj-$(CONFIG_AB3100_CORE)	+= ab3100-core.o
> +obj-$(CONFIG_AB3100_CORE)	+= ab3100-core.o ab3100-otp.o
> diff --git a/drivers/mfd/ab3100-otp.c b/drivers/mfd/ab3100-otp.c
> new file mode 100644
> index 0000000..48d998c
> --- /dev/null
> +++ b/drivers/mfd/ab3100-otp.c
> @@ -0,0 +1,123 @@
> +/*
> + * drivers/mfd/ab3100_otp.c
> + *
> + * Copyright (C) 2007-2009 ST-Ericsson AB
> + * License terms: GNU General Public License (GPL) version 2
> + * Driver to read out OTP from the AB3100 Mixed-signal circuit
> + * Author: Linus Walleij <linus.walleij@stericsson.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/ab3100.h>
> +
> +/* The OTP registers */
> +#define AB3100_OTP0		0xb0
> +#define AB3100_OTP1		0xb1
> +#define AB3100_OTP2		0xb2
> +#define AB3100_OTP3		0xb3
> +#define AB3100_OTP4		0xb4
> +#define AB3100_OTP5		0xb5
> +#define AB3100_OTP6		0xb6
> +#define AB3100_OTP7		0xb7
> +#define AB3100_OTPP		0xbf
> +
> +static ssize_t show_otp(struct device *dev,
> +			struct device_attribute *attr, char *buf)
> +{
> +	struct ab3100 *ab = dev_get_drvdata(dev);
> +	u8 otpval[8];
> +	u8 otpp;
> +	u16 cid; /* Customer ID */
> +	u32 tac; /* Type Allocation Code */
> +	u8 fac;  /* Final Assembly Code */
> +	u32 svn; /* Software Version Number */
> +	int err;
> +	char *bufp = buf;
> +
> +	err = ab3100_get_register_interruptible(ab, AB3100_OTPP, &otpp);
> +	if (err) {
> +		printk(KERN_ERR "Unable to read OTPP register\n");
> +		return err;
> +	}
> +
> +	err = ab3100_get_register_page_interruptible(ab, AB3100_OTP0,
> +						     otpval, 8);
> +	if (err) {
> +		printk(KERN_ERR "Unable to read OTPO register\n");
> +		return err;
> +	}
> +
> +	bufp += sprintf(bufp, "OTP is %s\n",
> +			(otpp & 0x80) ? "LOCKED" : "UNLOCKED");
> +
> +	bufp += sprintf(bufp, "OTP clock switch startup is %s\n",
> +			(otpp & 0x40) ? "32kHz" : "34.1kHz (1MHz/30)");
> +
> +	bufp += sprintf(bufp, "PAF is %s\n",
> +			(otpval[1] & 0x80) ? "SET" : "NOT SET");
> +
> +	bufp += sprintf(bufp, "IMEI is %s\n",
> +			(otpval[1] & 0x40) ? "CHANGEABLE" : "NOT CHANGEABLE");
> +
> +	cid = ((otpval[1] << 8) | otpval[0]) & 0x3fff;
> +	bufp += sprintf(bufp, "CID: 0x%04x (decimal: %d)\n", cid, cid);
> +	tac = ((otpval[4] & 0x0f) << 16) | (otpval[3] << 8) | otpval[2];
> +	fac = ((otpval[5] & 0x0f) << 4) | (otpval[4] >> 4);
> +	svn = (otpval[7] << 12) | (otpval[6] << 4) | (otpval[5] >> 4);
> +	bufp += sprintf(bufp, "IMEI: %u-%u-%u\n", tac, fac, svn);
> +
> +	return bufp-buf;
> +}
> +
> +static DEVICE_ATTR(otp, S_IRUGO, show_otp, NULL);
> +
> +static int __init ab3100_otp_probe(struct platform_device *pdev)
> +{
> +	int err;
> +
> +	dev_info(&pdev->dev, "AB3100 OTP readout registered\n");
> +
> +	/* sysfs entries */
> +	err = device_create_file(&pdev->dev, &dev_attr_otp);
> +	if (err != 0) {
> +		dev_err(&pdev->dev, "AB3100 OTP file registration failed!\n");
> +		return err;
> +	}
> +	return 0;
> +}
> +
> +static int __exit ab3100_otp_remove(struct platform_device *pdev)
> +{
> +	device_remove_file(&pdev->dev, &dev_attr_otp);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver ab3100_otp_driver = {
> +	.driver = {
> +		.name = "ab3100-otp",
> +		.owner = THIS_MODULE,
> +	},
> +	.remove	 = __exit_p(ab3100_otp_remove),
> +};
> +
> +static int __init ab3100_otp_init(void)
> +{
> +	return platform_driver_probe(&ab3100_otp_driver,
> +				     ab3100_otp_probe);
> +}
> +
> +static void __exit ab3100_otp_exit(void)
> +{
> +	platform_driver_unregister(&ab3100_otp_driver);
> +}
> +
> +module_init(ab3100_otp_init);
> +module_exit(ab3100_otp_exit);
> +
> +MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
> +MODULE_DESCRIPTION("AB3100 OTP Readout Driver");
> +MODULE_LICENSE("GPL");
> -- 
> 1.6.2.1
> 

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