[PATCH v6 2/4] firmware: keembay: Add support for Trusted Firmware Service call

[muhammad . husaini . zulkifli]

From: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@xxxxxxxxx>

Export inline function to encapsulate AON_CFG1 for controling the
I/O Rail supplied voltage levels which communicate with Trusted Firmware.

Signed-off-by: Muhammad Husaini Zulkifli <muhammad.husaini.zulkifli@xxxxxxxxx>
Acked-by: Michal Simek <michal.simek@xxxxxxxxxx>
Acked-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
 include/linux/firmware/intel/keembay.h | 54 ++++++++++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 include/linux/firmware/intel/keembay.h

diff --git a/include/linux/firmware/intel/keembay.h b/include/linux/firmware/intel/keembay.h
new file mode 100644
index 000000000000..b5e3e490807e
--- /dev/null
+++ b/include/linux/firmware/intel/keembay.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  Intel Keembay SOC Firmware API Layer
+ *
+ *  Copyright (C) 2020, Intel Corporation
+ *
+ *  Author: Muhammad Husaini Zulkifli <Muhammad.Husaini.Zulkifli@xxxxxxxxx>
+ */
+
+#ifndef __FIRMWARE_KEEMBAY_SMC_H__
+#define __FIRMWARE_KEEMBAY_SMC_H__
+
+#include <linux/arm-smccc.h>
+
+/*
+ * This file defines an API function that can be called by a device driver in order to
+ * communicate with Trusted Firmware - A profile(TF-A) or Trusted Firmware - M profile (TF-M).
+ */
+
+#define KEEMBAY_SET_1V8_IO_RAIL	1
+#define KEEMBAY_SET_3V3_IO_RAIL	0
+
+#define IOV_1V8			1800000
+#define IOV_3V3			3300000
+
+#define ARM_SMCCC_SIP_KEEMBAY_SET_SD_VOLTAGE		\
+	ARM_SMCCC_CALL_VAL(ARM_SMCCC_FAST_CALL,		\
+			   ARM_SMCCC_SMC_32,		\
+			   ARM_SMCCC_OWNER_SIP,		\
+			   0xFF26)
+
+#if IS_ENABLED(CONFIG_HAVE_ARM_SMCCC_DISCOVERY)
+/*
+ * Voltage applied on the IO Rail is controlled from the Always On Register using specific
+ * bits in AON_CGF1 register. This is a secure register. Keem Bay SOC cannot exposed this
+ * register address to the outside world.
+ */
+static inline int keembay_io_rail_supplied_voltage(int volt)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_1_1_invoke(ARM_SMCCC_SIP_KEEMBAY_SET_SD_VOLTAGE, volt, &res);
+	if ((int)res.a0 < 0)
+		return -EINVAL;
+
+	return 0;
+}
+#else
+static inline int keembay_io_rail_supplied_voltage(int volt)
+{
+	return -ENODEV;
+}
+#endif
+#endif /* __FIRMWARE_KEEMBAY_SMC_H__ */
-- 
2.17.1