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. Subsequent patch will use this function.

Suggested-by: Srinivas Kandagatla <srinivas.kandaga...@linaro.org>
Signed-off-by: Mukesh Ojha <quic_mo...@quicinc.com>
---
 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 fde33acd46b7..5ea8fc4fd4e8 100644
--- a/drivers/firmware/qcom_scm.c
+++ b/drivers/firmware/qcom_scm.c
@@ -78,6 +78,7 @@ static const char * const qcom_scm_convention_names[] = {
 };
 
 static struct qcom_scm *__scm;
+static DEFINE_SPINLOCK(lock);
 
 static int qcom_scm_clk_enable(void)
 {
@@ -407,6 +408,25 @@ int qcom_scm_set_remote_state(u32 state, u32 id)
 }
 EXPORT_SYMBOL(qcom_scm_set_remote_state);
 
+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 250ea4efb7cb..ca41e4eb33ad 100644
--- a/include/linux/firmware/qcom/qcom_scm.h
+++ b/include/linux/firmware/qcom/qcom_scm.h
@@ -84,6 +84,8 @@ extern bool qcom_scm_pas_supported(u32 peripheral);
 
 extern int qcom_scm_io_readl(phys_addr_t addr, unsigned int *val);
 extern int qcom_scm_io_writel(phys_addr_t addr, unsigned int val);
+extern int qcom_scm_io_update_field(phys_addr_t addr, unsigned int mask,
+                                   unsigned int val);
 
 extern bool qcom_scm_restore_sec_cfg_available(void);
 extern int qcom_scm_restore_sec_cfg(u32 device_id, u32 spare);
-- 
2.7.4

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