linux-kernel - Re: [PATCH v4] eeprom/at24: use device_property_*() functions instead of of_get

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Date:   Thu, 9 Feb 2017 19:43:20 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Ben Gardner <gardner.ben@...il.com>
Cc:     Wolfram Sang <wsa@...-dreams.de>, linux-i2c@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4] eeprom/at24: use device_property_*() functions instead
 of of_get_property()

On Thu, Feb 9, 2017 at 7:36 PM, Ben Gardner <gardner.ben@...il.com> wrote:
> Allow the at24 driver to get configuration information from both OF and
> ACPI by using the more generic device_property functions.
> This change was inspired by the at25.c driver.
>
> I have a custom board with a ST M24C02 EEPROM attached to an I2C bus.
> With the following ACPI construct, this patch instantiates a working
> instance of the driver.
>
> Device (EEP0) {
>  Name (_HID, "PRP0001")
>  Name (_DSD, Package () {
>   ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
>   Package () {
>    Package () {"compatible", Package () {"st,24c02"}},
>    Package () {"pagesize", 16},
>   },
>  })
>  Name (_CRS, ResourceTemplate () {
>   I2cSerialBus (
>    0x0057, ControllerInitiated, 400000,
>    AddressingMode7Bit, "\\_SB.PCI0.I2C3", 0x00,
>    ResourceConsumer,,)
>  })
> }
>
> Note: Matching the driver to the I2C device requires another patch.
>  http://www.spinics.net/lists/linux-acpi/msg71914.html

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: Ben Gardner <gardner.ben@...il.com>
> ---
>  drivers/misc/eeprom/at24.c | 45 +++++++++++++++++++--------------------------
>  1 file changed, 19 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/misc/eeprom/at24.c b/drivers/misc/eeprom/at24.c
> index 051b147..764ff5df 100644
> --- a/drivers/misc/eeprom/at24.c
> +++ b/drivers/misc/eeprom/at24.c
> @@ -19,7 +19,7 @@
>  #include <linux/log2.h>
>  #include <linux/bitops.h>
>  #include <linux/jiffies.h>
> -#include <linux/of.h>
> +#include <linux/property.h>
>  #include <linux/acpi.h>
>  #include <linux/i2c.h>
>  #include <linux/nvmem-provider.h>
> @@ -562,26 +562,26 @@ static int at24_write(void *priv, unsigned int off, void *val, size_t count)
>         return 0;
>  }
>
> -#ifdef CONFIG_OF
> -static void at24_get_ofdata(struct i2c_client *client,
> -                           struct at24_platform_data *chip)
> +static void at24_get_pdata(struct device *dev, struct at24_platform_data *chip)
>  {
> -       const __be32 *val;
> -       struct device_node *node = client->dev.of_node;
> -
> -       if (node) {
> -               if (of_get_property(node, "read-only", NULL))
> -                       chip->flags |= AT24_FLAG_READONLY;
> -               val = of_get_property(node, "pagesize", NULL);
> -               if (val)
> -                       chip->page_size = be32_to_cpup(val);
> +       int err;
> +       u32 val;
> +
> +       if (device_property_present(dev, "read-only"))
> +               chip->flags |= AT24_FLAG_READONLY;
> +
> +       err = device_property_read_u32(dev, "pagesize", &val);
> +       if (!err) {
> +               chip->page_size = val;
> +       } else {
> +               /*
> +                * This is slow, but we can't know all eeproms, so we better
> +                * play safe. Specifying custom eeprom-types via platform_data
> +                * is recommended anyhow.
> +                */
> +               chip->page_size = 1;
>         }
>  }
> -#else
> -static void at24_get_ofdata(struct i2c_client *client,
> -                           struct at24_platform_data *chip)
> -{ }
> -#endif /* CONFIG_OF */
>
>  static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  {
> @@ -613,15 +613,8 @@ static int at24_probe(struct i2c_client *client, const struct i2c_device_id *id)
>                 chip.byte_len = BIT(magic & AT24_BITMASK(AT24_SIZE_BYTELEN));
>                 magic >>= AT24_SIZE_BYTELEN;
>                 chip.flags = magic & AT24_BITMASK(AT24_SIZE_FLAGS);
> -               /*
> -                * This is slow, but we can't know all eeproms, so we better
> -                * play safe. Specifying custom eeprom-types via platform_data
> -                * is recommended anyhow.
> -                */
> -               chip.page_size = 1;
>
> -               /* update chipdata if OF is present */
> -               at24_get_ofdata(client, &chip);
> +               at24_get_pdata(&client->dev, &chip);
>
>                 chip.setup = NULL;
>                 chip.context = NULL;
> --
> 2.7.4
>



-- 
With Best Regards,
Andy Shevchenko