[PATCH 1/3] soc: qcom: smem_state: Add devm_qcom_smem_state_get()

[Stephan Gerhold <stephan@gerhold.net>]

It is easy to forget to call qcom_smem_state_put() after
a qcom_smem_state_get(). Introduce a devm_qcom_smem_state_get()
helper function that automates this so that qcom_smem_state_put()
is automatically called when a device is removed.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
---
I use this in my WIP bam-dmux driver, so it might simplify coordination
later if we can somehow get this in for 5.14 (if it isn't too late yet).

Similar code can be found in clk-devres.c for example:
https://elixir.bootlin.com/linux/v5.13-rc6/source/drivers/clk/clk-devres.c#L7
---
 drivers/soc/qcom/smem_state.c       | 36 +++++++++++++++++++++++++++++
 include/linux/soc/qcom/smem_state.h |  7 ++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/soc/qcom/smem_state.c b/drivers/soc/qcom/smem_state.c
index d2b558438deb..31faf4aa868e 100644
--- a/drivers/soc/qcom/smem_state.c
+++ b/drivers/soc/qcom/smem_state.c
@@ -151,6 +151,42 @@ void qcom_smem_state_put(struct qcom_smem_state *state)
 }
 EXPORT_SYMBOL_GPL(qcom_smem_state_put);
 
+static void devm_qcom_smem_state_release(struct device *dev, void *res)
+{
+	qcom_smem_state_put(*(struct qcom_smem_state **)res);
+}
+
+/**
+ * devm_qcom_smem_state_get() - acquire handle to a devres managed state
+ * @dev:	client device pointer
+ * @con_id:	name of the state to lookup
+ * @bit:	flags from the state reference, indicating which bit's affected
+ *
+ * Returns handle to the state, or ERR_PTR(). qcom_smem_state_put() is called
+ * automatically when @dev is removed.
+ */
+struct qcom_smem_state *devm_qcom_smem_state_get(struct device *dev,
+						 const char *con_id,
+						 unsigned *bit)
+{
+	struct qcom_smem_state **ptr, *state;
+
+	ptr = devres_alloc(devm_qcom_smem_state_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	state = qcom_smem_state_get(dev, con_id, bit);
+	if (!IS_ERR(state)) {
+		*ptr = state;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
+
+	return state;
+}
+EXPORT_SYMBOL_GPL(devm_qcom_smem_state_get);
+
 /**
  * qcom_smem_state_register() - register a new state
  * @of_node:	of_node used for matching client lookups
diff --git a/include/linux/soc/qcom/smem_state.h b/include/linux/soc/qcom/smem_state.h
index 63ad8cddad14..17c56a50302f 100644
--- a/include/linux/soc/qcom/smem_state.h
+++ b/include/linux/soc/qcom/smem_state.h
@@ -14,6 +14,7 @@ struct qcom_smem_state_ops {
 #ifdef CONFIG_QCOM_SMEM_STATE
 
 struct qcom_smem_state *qcom_smem_state_get(struct device *dev, const char *con_id, unsigned *bit);
+struct qcom_smem_state *devm_qcom_smem_state_get(struct device *dev, const char *con_id, unsigned *bit);
 void qcom_smem_state_put(struct qcom_smem_state *);
 
 int qcom_smem_state_update_bits(struct qcom_smem_state *state, u32 mask, u32 value);
@@ -29,6 +30,12 @@ static inline struct qcom_smem_state *qcom_smem_state_get(struct device *dev,
 	return ERR_PTR(-EINVAL);
 }
 
+static inline struct qcom_smem_state *devm_qcom_smem_state_get(struct device *dev,
+	const char *con_id, unsigned *bit)
+{
+	return ERR_PTR(-EINVAL);
+}
+
 static inline void qcom_smem_state_put(struct qcom_smem_state *state)
 {
 }
-- 
2.32.0