[PATCH v7 1/3] firmware: qcom_scm: provide a read-modify-write function

[Mukesh Ojha <quic_mojha@xxxxxxxxxxx>]

It was realized by Srinivas K. that there is a need of
read-modify-write scm exported function so that it can
be used by multiple clients.

Let's introduce qcom_scm_io_update_field() which masks
out the bits and write the passed value to that bit-offset.

Suggested-by: Srinivas Kandagatla <srinivas.kandagatla@xxxxxxxxxx>
Signed-off-by: Mukesh Ojha <quic_mojha@xxxxxxxxxxx>
Tested-by: Kathiravan Thirumoorthy <quic_kathirav@xxxxxxxxxxx> # IPQ9574 and IPQ5332
---
 drivers/firmware/qcom_scm.c            | 20 ++++++++++++++++++++
 include/linux/firmware/qcom/qcom_scm.h |  2 ++
 2 files changed, 22 insertions(+)

diff --git a/drivers/firmware/qcom_scm.c b/drivers/firmware/qcom_scm.c
index 520de9b5633a..084e4782b88d 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -122,6 +122,7 @@ static const char * const qcom_scm_convention_names[] = {
 };
 
 static struct qcom_scm *__scm;
+static DEFINE_SPINLOCK(lock);
 
 static int qcom_scm_clk_enable(void)
 {
@@ -481,6 +482,25 @@ static int qcom_scm_disable_sdi(void)
 	return ret ? : res.result[0];
 }
 
+int qcom_scm_io_update_field(phys_addr_t addr, unsigned int mask, unsigned int val)
+{
+	unsigned int old, new;
+	int ret;
+
+	spin_lock(&lock);
+	ret = qcom_scm_io_readl(addr, &old);
+	if (ret)
+		goto unlock;
+
+	new = (old & ~mask) | (val & mask);
+
+	ret = qcom_scm_io_writel(addr, new);
+unlock:
+	spin_unlock(&lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(qcom_scm_io_update_field);
+
 static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
 {
 	struct qcom_scm_desc desc = {
diff --git a/include/linux/firmware/qcom/qcom_scm.h b/include/linux/firmware/qcom/qcom_scm.h
index ccaf28846054..5497eaf9c7b5 100644
--- a/include/linux/firmware/qcom/qcom_scm.h
+++ b/include/linux/firmware/qcom/qcom_scm.h
@@ -82,6 +82,8 @@ bool qcom_scm_pas_supported(u32 peripheral);
 
 int qcom_scm_io_readl(phys_addr_t addr, unsigned int *val);
 int qcom_scm_io_writel(phys_addr_t addr, unsigned int val);
+int qcom_scm_io_update_field(phys_addr_t addr, unsigned int mask,
+			     unsigned int val);
 
 bool qcom_scm_restore_sec_cfg_available(void);
 int qcom_scm_restore_sec_cfg(u32 device_id, u32 spare);
-- 
2.7.4