ASoC: Rework initialization of i2c_device_ids

Uwe Kleine-König (The Capable Hub) <u.kleine-koenig@baylibre.com> says:

This series is a preparation for

	diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
	index 23ff24080dfd..aebd3a5e90af 100644
	--- a/include/linux/mod_devicetable.h
	+++ b/include/linux/mod_devicetable.h
	@@ -477,7 +477,11 @@ struct rpmsg_device_id {

	 struct i2c_device_id {
		char name[I2C_NAME_SIZE];
	-	kernel_ulong_t driver_data;	/* Data private to the driver */
	+	union {
	+		/* Data private to the driver */
	+		kernel_ulong_t driver_data;
	+		const void *driver_data_ptr;
	+	};
	 };

	 /* pci_epf */

and this requires that .driver_data is assigned via a named initializer
for static data. This requirement isn't a bad one because named
initializers are also much better readable than list initializers.

The union added to struct i2c_device_id enables further cleanups like:

        diff --git a/drivers/iio/accel/kxcjk-1013.c b/drivers/iio/accel/kxcjk-1013.c
        index 8a082ff034dd..b2aac7348d22 100644
        --- a/drivers/iio/accel/kxcjk-1013.c
        +++ b/drivers/iio/accel/kxcjk-1013.c
	@@ -1429,7 +1429,7 @@ static int kxcjk1013_probe(struct i2c_client *client)

		if (id) {
			name = id->name;
	-		data->info = (const struct kx_chipset_info *)(id->driver_data);
	+		data->info = id->driver_data_ptr;
		} else {
			name = iio_get_acpi_device_name_and_data(&client->dev, &ddata);
			data->info = ddata;
	@@ -1630,11 +1630,11 @@ static const struct dev_pm_ops kxcjk1013_pm_ops = {
	 };

	 static const struct i2c_device_id kxcjk1013_id[] = {
	-	{ .name = "kxcjk1013", .driver_data = (kernel_ulong_t)&kxcjk1013_info },
	-	{ .name = "kxcj91008", .driver_data = (kernel_ulong_t)&kxcj91008_info },
	-	{ .name = "kxtj21009", .driver_data = (kernel_ulong_t)&kxtj21009_info },
	-	{ .name = "kxtf9", .driver_data = (kernel_ulong_t)&kxtf9_info },
	-	{ .name = "kx023-1025", .driver_data = (kernel_ulong_t)&kx0231025_info },
	+	{ .name = "kxcjk1013", .driver_data_ptr = &kxcjk1013_info },
	+	{ .name = "kxcj91008", .driver_data_ptr = &kxcj91008_info },
	+	{ .name = "kxtj21009", .driver_data_ptr = &kxtj21009_info },
	+	{ .name = "kxtf9", .driver_data_ptr = &kxtf9_info },
	+	{ .name = "kx023-1025", .driver_data_ptr = &kx0231025_info },
		{ }
	 };
	 MODULE_DEVICE_TABLE(i2c, kxcjk1013_id);

that are an improvement for readability (again!) and it keeps some
properties of the pointers (here: being const) without having to pay
attention for that. (I didn't find a good example in sound/soc, so an
iio driver was used to demonstrate the gain.)

My additional motivation for this effort is CHERI[1]. This is a hardware
extension that uses 128 bit pointers but unsigned long is still 64 bit.
So with CHERI you cannot store pointers in unsigned long variables.

The first patch drops a few empty remove callbacks that I found while
working on patch #2. The second converts all hwmon drivers to use named
initializers.

Link: https://patch.msgid.link/cover.1778692164.git.u.kleine-koenig@baylibre.com

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