[PATCH v4 07/11] firmware: samsung: acpm: Add devm_acpm_get_by_phandle helper

[Tudor Ambarus <tudor.ambarus@linaro.org>]

Introduce devm_acpm_get_by_phandle() to standardize how consumer
drivers acquire a handle to the ACPM IPC interface. Enforce the
use of the "samsung,acpm-ipc" property name across the SoC and
simplify the boilerplate code in client drivers.

The first consumer of this helper is the Exynos ACPM Thermal Management
Unit (TMU) driver. The TMU utilizes a hybrid management approach: direct
register access from the Application Processor (AP) is restricted to the
interrupt pending (INTPEND) registers for event identification.
High-level functional tasks, such as sensor initialization, threshold
programming, and temperature reads, are delegated to the ACPM firmware
via this IPC interface.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
---
 drivers/firmware/samsung/exynos-acpm.c             | 23 ++++++++++++++++++++++
 .../linux/firmware/samsung/exynos-acpm-protocol.h  |  6 ++++++
 2 files changed, 29 insertions(+)

diff --git a/drivers/firmware/samsung/exynos-acpm.c b/drivers/firmware/samsung/exynos-acpm.c
index 655b80fc635f..6dee461f5827 100644
--- a/drivers/firmware/samsung/exynos-acpm.c
+++ b/drivers/firmware/samsung/exynos-acpm.c
@@ -812,6 +812,29 @@ struct acpm_handle *devm_acpm_get_by_node(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(devm_acpm_get_by_node);
 
+/**
+ * devm_acpm_get_by_phandle - Resource managed lookup of the standardized
+ * "samsung,acpm-ipc" handle.
+ * @dev: consumer device
+ *
+ * Returns a pointer to the acpm_handle on success, or an ERR_PTR on failure.
+ */
+struct acpm_handle *devm_acpm_get_by_phandle(struct device *dev)
+{
+	struct acpm_handle *handle;
+	struct device_node *np;
+
+	np = of_parse_phandle(dev->of_node, "samsung,acpm-ipc", 0);
+	if (!np)
+		return ERR_PTR(-ENODEV);
+
+	handle = devm_acpm_get_by_node(dev, np);
+	of_node_put(np);
+
+	return handle;
+}
+EXPORT_SYMBOL_GPL(devm_acpm_get_by_phandle);
+
 static const struct acpm_match_data acpm_gs101 = {
 	.initdata_base = ACPM_GS101_INITDATA_BASE,
 	.acpm_clk_dev_name = "gs101-acpm-clk",
diff --git a/include/linux/firmware/samsung/exynos-acpm-protocol.h b/include/linux/firmware/samsung/exynos-acpm-protocol.h
index 08d9f5c95701..83cbd425b652 100644
--- a/include/linux/firmware/samsung/exynos-acpm-protocol.h
+++ b/include/linux/firmware/samsung/exynos-acpm-protocol.h
@@ -71,6 +71,7 @@ struct device;
 #if IS_ENABLED(CONFIG_EXYNOS_ACPM_PROTOCOL)
 struct acpm_handle *devm_acpm_get_by_node(struct device *dev,
 					  struct device_node *np);
+struct acpm_handle *devm_acpm_get_by_phandle(struct device *dev);
 #else
 
 static inline struct acpm_handle *devm_acpm_get_by_node(struct device *dev,
@@ -78,6 +79,11 @@ static inline struct acpm_handle *devm_acpm_get_by_node(struct device *dev,
 {
 	return ERR_PTR(-ENODEV);
 }
+
+static inline struct acpm_handle *devm_acpm_get_by_phandle(struct device *dev)
+{
+	return ERR_PTR(-ENODEV);
+}
 #endif
 
 #endif /* __EXYNOS_ACPM_PROTOCOL_H */

-- 
2.54.0.545.g6539524ca2-goog