mfd: dln2: Add cell for initializing DLN2 ADC

This patch extends the DLN2 driver; adding cell for adc_dln2 module.

The original patch[1] fell through the cracks when the driver was added
so ADC has never actually been usable. That patch did not have ACPI
support which was added in v5.9, so the oldest supported version this
current patch can be backported to is 5.10.

[1] https://www.spinics.net/lists/linux-iio/msg33975.html

Cc: <stable@vger.kernel.org> # 5.10+
Signed-off-by: Jack Andersen <jackoalan@gmail.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20211018112541.25466-1-noralf@tronnes.org

drivers/mfd/dln2.c

@@ -50,6 +50,7 @@ enum dln2_handle {
 	DLN2_HANDLE_GPIO,
 	DLN2_HANDLE_I2C,
 	DLN2_HANDLE_SPI,
+	DLN2_HANDLE_ADC,
 	DLN2_HANDLES
 };
 
@@ -653,6 +654,7 @@ enum {
 	DLN2_ACPI_MATCH_GPIO	= 0,
 	DLN2_ACPI_MATCH_I2C	= 1,
 	DLN2_ACPI_MATCH_SPI	= 2,
+	DLN2_ACPI_MATCH_ADC	= 3,
 };
 
 static struct dln2_platform_data dln2_pdata_gpio = {
@@ -683,6 +685,16 @@ static struct mfd_cell_acpi_match dln2_acpi_match_spi = {
 	.adr = DLN2_ACPI_MATCH_SPI,
 };
 
+/* Only one ADC port supported */
+static struct dln2_platform_data dln2_pdata_adc = {
+	.handle = DLN2_HANDLE_ADC,
+	.port = 0,
+};
+
+static struct mfd_cell_acpi_match dln2_acpi_match_adc = {
+	.adr = DLN2_ACPI_MATCH_ADC,
+};
+
 static const struct mfd_cell dln2_devs[] = {
 	{
 		.name = "dln2-gpio",
@@ -702,6 +714,12 @@ static const struct mfd_cell dln2_devs[] = {
 		.platform_data = &dln2_pdata_spi,
 		.pdata_size = sizeof(struct dln2_platform_data),
 	},
+	{
+		.name = "dln2-adc",
+		.acpi_match = &dln2_acpi_match_adc,
+		.platform_data = &dln2_pdata_adc,
+		.pdata_size = sizeof(struct dln2_platform_data),
+	},
 };
 
 static void dln2_stop(struct dln2_dev *dln2)