[PATCH v3 2/5] spi: add devm_spi_new_ancillary_device()

[Antoniu Miclaus <antoniu.miclaus@analog.com>]

Add a devres-managed version of spi_new_ancillary_device() that
automatically unregisters the ancillary SPI device when the parent
device is removed.

This follows the same devm_add_action_or_reset() pattern used by the
other managed SPI functions (devm_spi_optimize_message,
devm_spi_register_controller, etc.) and eliminates the need for drivers
to open-code their own devm cleanup callbacks for ancillary devices.

Signed-off-by: Antoniu Miclaus <antoniu.miclaus@analog.com>
---
Changes in v3:
  - New patch

 drivers/spi/spi.c       | 40 ++++++++++++++++++++++++++++++++++++++++
 include/linux/spi/spi.h |  1 +
 2 files changed, 41 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 693bdcc5a12a..1b48ec67b8e0 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2612,6 +2612,46 @@ struct spi_device *spi_new_ancillary_device(struct spi_device *spi,
 }
 EXPORT_SYMBOL_GPL(spi_new_ancillary_device);
 
+static void devm_spi_unregister_device(void *spi)
+{
+	spi_unregister_device(spi);
+}
+
+/**
+ * devm_spi_new_ancillary_device() - Register managed ancillary SPI device
+ * @spi:         Pointer to the main SPI device registering the ancillary device
+ * @chip_select: Chip Select of the ancillary device
+ *
+ * Register an ancillary SPI device; for example some chips have a chip-select
+ * for normal device usage and another one for setup/firmware upload.
+ *
+ * This is the managed version of spi_new_ancillary_device(). The ancillary
+ * device will be unregistered automatically when the parent SPI device is
+ * unregistered.
+ *
+ * This may only be called from main SPI device's probe routine.
+ *
+ * Return: Pointer to new ancillary device on success; ERR_PTR on failure
+ */
+struct spi_device *devm_spi_new_ancillary_device(struct spi_device *spi,
+						 u8 chip_select)
+{
+	struct spi_device *ancillary;
+	int ret;
+
+	ancillary = spi_new_ancillary_device(spi, chip_select);
+	if (IS_ERR(ancillary))
+		return ancillary;
+
+	ret = devm_add_action_or_reset(&spi->dev, devm_spi_unregister_device,
+				       ancillary);
+	if (ret)
+		return ERR_PTR(ret);
+
+	return ancillary;
+}
+EXPORT_SYMBOL_GPL(devm_spi_new_ancillary_device);
+
 #ifdef CONFIG_ACPI
 struct acpi_spi_lookup {
 	struct spi_controller 	*ctlr;
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index cb2c2df31089..9aef1987b12f 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -374,6 +374,7 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
 }
 
 extern struct spi_device *spi_new_ancillary_device(struct spi_device *spi, u8 chip_select);
+extern struct spi_device *devm_spi_new_ancillary_device(struct spi_device *spi, u8 chip_select);
 
 /* Use a define to avoid include chaining to get THIS_MODULE */
 #define spi_register_driver(driver) \
-- 
2.43.0