linux-kernel - [PATCH RFC 0/4] Start unification of of_device_id and i2c_device

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Message-ID: <20230814-i2c-id-rework-v1-0-3e5bc71c49ee@gmail.com>
Date:   Mon, 14 Aug 2023 14:52:48 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Wolfram Sang <wsa@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Andi Shyti <andi.shyti@...nel.org>,
        Biju Das <biju.das.jz@...renesas.com>,
        Jonathan Cameron <jic23@...nel.org>,
        Michael Hennerich <michael.hennerich@...log.com>,
        Peter Rosin <peda@...ntia.se>
Cc:     linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH RFC 0/4] Start unification of of_device_id and i2c_device_id

i2c_device_id is using unsigned long as driver data, whereas
of_device_id is using a void pointer. Normally drivers use them both as
either a pointer or a scalar, but in some cases driver's authors chose
to treat one as a pointer and another as a scalar that is being used as
an index in array of chip-specific data, i.e. something like this:

	data = device_get_match_data(...);
	if (!data) {
		id = i2c_client_get_device_id(...);
		data = &some_array[id->driver_data];
	}

This makes it hard to turn device_get_match_data() into truly generic
function working well for ACPI and DT, as well as for legacy cases.

So let's try to switch i2c_device_id to also use a void pointer and
first switch drivers with the patterns above to it, and then the rest of
them.

I did a conversion of a couple of drivers in i2c to illustrate.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
Dmitry Torokhov (4):
      i2c: start migrating to a pointer in i2c_device_id
      i2c: mux: ltc4306: convert to using a pointer in i2c_device_id
      i2c: mux: pca954x: convert to using a pointer in i2c_device_id
      i2c: slave-eeprom: convert to using a pointer in i2c_device_id

 drivers/i2c/i2c-core-base.c         |  2 +-
 drivers/i2c/i2c-slave-eeprom.c      | 99 ++++++++++++++++++++++++-------------
 drivers/i2c/muxes/i2c-mux-ltc4306.c |  7 ++-
 drivers/i2c/muxes/i2c-mux-pca954x.c | 28 +++++------
 include/linux/mod_devicetable.h     |  3 +-
 5 files changed, 86 insertions(+), 53 deletions(-)
---
base-commit: 21ef7b1e17d039053edaeaf41142423810572741
change-id: 20230814-i2c-id-rework-9a4742e9ee52

Best regards,
-- 
Dmitry