bsec: add scratch register access API

Add read/write functions for BSEC scratch register, used for communication
with external agent, and to store boot parameters.

Change-Id: If024bcce127c829d8a663df0119f0e908712405e
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
Reviewed-on: https://gerrit.st.com/c/mpu/oe/st/tf-a/+/187860


Reviewed-by: CITOOLS <smet-aci-reviews@lists.codex.cro.st.com>
Reviewed-by: Yann GAUTIER <yann.gautier@st.com>

drivers/st/bsec/bsec2.c

@@ -637,6 +637,26 @@ uint32_t bsec_read_debug_conf(void)
 	return mmio_read_32(bsec_base + BSEC_DEN_OFF);
 }
 
+/*
+ * bsec_write_scratch: write value in scratch register.
+ * val: value to write.
+ * return value: none.
+ */
+void bsec_write_scratch(uint32_t val)
+{
+	bsec_lock();
+	mmio_write_32(bsec_base + BSEC_SCRATCH_OFF, val);
+	bsec_unlock();
+}
+
+/*
+ * bsec_read_scratch: return scratch register value.
+ */
+uint32_t bsec_read_scratch(void)
+{
+	return mmio_read_32(bsec_base + BSEC_SCRATCH_OFF);
+}
+
 /*
  * bsec_get_status: return status register value.
  */

include/drivers/st/bsec.h

@@ -108,6 +108,9 @@ uint32_t bsec_permanent_lock_otp(uint32_t otp);
 void bsec_write_debug_conf(uint32_t val);
 uint32_t bsec_read_debug_conf(void);
 
+void bsec_write_scratch(uint32_t val);
+uint32_t bsec_read_scratch(void);
+
 uint32_t bsec_get_status(void);
 uint32_t bsec_get_hw_conf(void);
 uint32_t bsec_get_version(void);