Re: [PATCH 5/5] eeprom: at24: Convert the driver to NVMEM

[Antony Pavlov <antonynpavlov@gmail.com>]

On Mon, 12 Aug 2019 13:19:15 -0700
Andrey Smirnov <andrew.smirnov@gmail.com> wrote:

Hi!

Could you please test this patch with disabled NVMEM?

I see that this patch leads to barebox crash in memory allocation code
if CONFIG_NVMEM is not set.

> Convert AT24 driver to use NVMEM subsystem instead of explicitly
> creating a dedicated cdev. This way it becomes possible to access the
> contenst of EEPROM via NVMEM API, which could be usefull for things
> like MAC-addresses and such.
> 
> Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
> ---
>  drivers/eeprom/at24.c | 48 ++++++++++++++++++++++++-------------------
>  1 file changed, 27 insertions(+), 21 deletions(-)
> 
> diff --git a/drivers/eeprom/at24.c b/drivers/eeprom/at24.c
> index db452c1076..568aa02a4c 100644
> --- a/drivers/eeprom/at24.c
> +++ b/drivers/eeprom/at24.c
> @@ -23,6 +23,8 @@
>  #include <gpio.h>
>  #include <of_gpio.h>
>  
> +#include <linux/nvmem-provider.h>
> +
>  /*
>   * I2C EEPROMs from most vendors are inexpensive and mostly interchangeable.
>   * Differences between different vendor product lines (like Atmel AT24C or
> @@ -50,8 +52,8 @@
>  struct at24_data {
>  	struct at24_platform_data chip;
>  
> -	struct cdev		cdev;
> -	struct cdev_operations	fops;
> +	struct nvmem_config nvmem_config;
> +	struct nvmem_device *nvmem;
>  
>  	u8 *writebuf;
>  	unsigned write_max;
> @@ -242,10 +244,10 @@ static ssize_t at24_read(struct at24_data *at24,
>  	return retval;
>  }
>  
> -static ssize_t at24_cdev_read(struct cdev *cdev, void *buf, size_t count,
> -		loff_t off, ulong flags)
> +static int at24_nvmem_read(struct device_d *dev, int off,
> +			       void *buf, int count)
>  {
> -	struct at24_data *at24 = cdev->priv;
> +	struct at24_data *at24 = dev->parent->priv;
>  
>  	return at24_read(at24, buf, off, count);
>  }
> @@ -360,14 +362,19 @@ static ssize_t at24_write(struct at24_data *at24, const char *buf, loff_t off,
>  	return retval;
>  }
>  
> -static ssize_t at24_cdev_write(struct cdev *cdev, const void *buf, size_t count,
> -		loff_t off, ulong flags)
> +static int at24_nvmem_write(struct device_d *dev, const int off,
> +			       const void *buf, int count)
>  {
> -	struct at24_data *at24 = cdev->priv;
> +	struct at24_data *at24 = dev->parent->priv;
>  
>  	return at24_write(at24, buf, off, count);
>  }
>  
> +static const struct nvmem_bus at24_nvmem_bus = {
> +	.write = at24_nvmem_write,
> +	.read  = at24_nvmem_read,
> +};
> +
>  static int at24_probe(struct device_d *dev)
>  {
>  	struct i2c_client *client = to_i2c_client(dev);
> @@ -441,13 +448,6 @@ static int at24_probe(struct device_d *dev)
>  		devname = xasprintf("eeprom%d", err);
>  	}
>  
> -	at24->cdev.name = devname;
> -	at24->cdev.priv = at24;
> -	at24->cdev.dev = dev;
> -	at24->cdev.ops = &at24->fops;
> -	at24->fops.read	= at24_cdev_read,
> -	at24->cdev.size = chip.byte_len;
> -
>  	writable = !(chip.flags & AT24_FLAG_READONLY);
>  
>  	if (of_get_property(dev->device_node, "read-only", NULL))
> @@ -456,8 +456,6 @@ static int at24_probe(struct device_d *dev)
>  	if (writable) {
>  		unsigned write_max = chip.page_size;
>  
> -		at24->fops.write = at24_cdev_write;
> -
>  		if (write_max > io_limit)
>  			write_max = io_limit;
>  		at24->write_max = write_max;
> @@ -494,13 +492,21 @@ static int at24_probe(struct device_d *dev)
>  		}
>  	}
>  
> -	err = devfs_create(&at24->cdev);
> +	at24->nvmem_config.name = devname;
> +	at24->nvmem_config.dev = dev;
> +	at24->nvmem_config.read_only = !writable;
> +	at24->nvmem_config.bus = &at24_nvmem_bus;
> +	at24->nvmem_config.stride = 1;
> +	at24->nvmem_config.word_size = 1;
> +	at24->nvmem_config.size = chip.byte_len;
> +
> +	dev->priv = at24;
> +
> +	at24->nvmem = nvmem_register(&at24->nvmem_config);
> +	err = PTR_ERR_OR_ZERO(at24->nvmem);
>  	if (err)
>  		goto err_devfs_create;
>  
> -	of_parse_partitions(&at24->cdev, dev->device_node);
> -	of_partitions_register_fixup(&at24->cdev);
> -
>  	return 0;
>  
>  err_devfs_create:
> -- 
> 2.21.0
> 
> 
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-- 
Best regards,
  Antony Pavlov

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