[PATCH v10 1/4] firmware: qcom: scm: provide a read-modify-write function

[Mukesh Ojha <quic_mojha@quicinc.com>]

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_rmw() which masks out the bits
and write the passed value to that bit-offset.

Suggested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Mukesh Ojha <quic_mojha@quicinc.com>
Tested-by: Kathiravan Thirumoorthy <quic_kathirav@quicinc.com> # IPQ9574 and IPQ5332
---
 drivers/firmware/qcom/qcom_scm.c       | 26 ++++++++++++++++++++++++++
 include/linux/firmware/qcom/qcom_scm.h |  1 +
 2 files changed, 27 insertions(+)

diff --git a/drivers/firmware/qcom/qcom_scm.c b/drivers/firmware/qcom/qcom_scm.c
index 520de9b5633a..25549178a30f 100644
--- a/drivers/firmware/qcom/qcom_scm.c
+++ b/drivers/firmware/qcom/qcom_scm.c
@@ -19,6 +19,7 @@
 #include <linux/of_irq.h>
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
+#include <linux/spinlock.h>
 #include <linux/reset-controller.h>
 #include <linux/types.h>
 
@@ -41,6 +42,8 @@ struct qcom_scm {
 	int scm_vote_count;
 
 	u64 dload_mode_addr;
+	/* Atomic context only */
+	spinlock_t lock;
 };
 
 struct qcom_scm_current_perm_info {
@@ -481,6 +484,28 @@ static int qcom_scm_disable_sdi(void)
 	return ret ? : res.result[0];
 }
 
+int qcom_scm_io_rmw(phys_addr_t addr, unsigned int mask, unsigned int val)
+{
+	unsigned int old, new;
+	int ret;
+
+	if (!__scm)
+		return -EINVAL;
+
+	spin_lock(&__scm->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(&__scm->lock);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(qcom_scm_io_rmw);
+
 static int __qcom_scm_set_dload_mode(struct device *dev, bool enable)
 {
 	struct qcom_scm_desc desc = {
@@ -1824,6 +1849,7 @@ static int qcom_scm_probe(struct platform_device *pdev)
 		return ret;
 
 	mutex_init(&scm->scm_bw_lock);
+	spin_lock_init(&scm->lock);
 
 	scm->path = devm_of_icc_get(&pdev->dev, NULL);
 	if (IS_ERR(scm->path))
diff --git a/include/linux/firmware/qcom/qcom_scm.h b/include/linux/firmware/qcom/qcom_scm.h
index ccaf28846054..3a8bb2e603b3 100644
--- a/include/linux/firmware/qcom/qcom_scm.h
+++ b/include/linux/firmware/qcom/qcom_scm.h
@@ -82,6 +82,7 @@ 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_rmw(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