[RFC PATCH v2 2/4] psci: add features/reset2 support

[Igor Opaniuk]

From: Igor Opaniuk <igor.opaniuk at foundries.io>

Adds support for:
* PSCI_FEATURES, which was introduced in PSCI 1.0. This provides API
that allows discovering whether a specific PSCI function is implemented
and its features.
* SYSTEM_RESET2, which was introduced in PSCI 1.1, which extends existing
SYSTEM_RESET. It provides support for vendor-specific resets, providing
reset_type as an additional param.

For additional details visit [1].

Implementations of some functions were borrowed from Linux PSCI driver
code [2].

[1] https://developer.arm.com/documentation/den0022/latest/
[2] drivers/firmware/psci/psci.c

Signed-off-by: Igor Opaniuk <igor.opaniuk at foundries.io>
---

(no changes since v1)

 drivers/firmware/psci.c | 70 +++++++++++++++++++++++++++++++++++++++++
 include/linux/psci.h    |  3 ++
 2 files changed, 73 insertions(+)

diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
index 68953cc4f4..8416cd445f 100644
--- a/drivers/firmware/psci.c
+++ b/drivers/firmware/psci.c
@@ -13,6 +13,7 @@
 #include <log.h>
 #include <dm/lists.h>
 #include <efi_loader.h>
+#include <sysreset.h>
 #include <linux/delay.h>
 #include <linux/libfdt.h>
 #include <linux/arm-smccc.h>
@@ -26,12 +27,26 @@
 #define PSCI_METHOD_HVC 1
 #define PSCI_METHOD_SMC 2
 
+/*
+ * While a 64-bit OS can make calls with SMC32 calling conventions, for some
+ * calls it is necessary to use SMC64 to pass or return 64-bit values.
+ * For such calls PSCI_FN_NATIVE(version, name) will choose the appropriate
+ * (native-width) function ID.
+ */
+#if defined(CONFIG_ARM64)
+#define PSCI_FN_NATIVE(version, name)	PSCI_##version##_FN64_##name
+#else
+#define PSCI_FN_NATIVE(version, name)	PSCI_##version##_FN_##name
+#endif
+
 #if CONFIG_IS_ENABLED(EFI_LOADER)
 int __efi_runtime_data psci_method;
 #else
 int psci_method __attribute__ ((section(".data")));
 #endif
 
+static bool reset2_supported;
+
 unsigned long __efi_runtime invoke_psci_fn
 		(unsigned long function_id, unsigned long arg0,
 		 unsigned long arg1, unsigned long arg2)
@@ -53,6 +68,27 @@ unsigned long __efi_runtime invoke_psci_fn
 	return res.a0;
 }
 
+static int psci_features(u32 psci_func_id)
+{
+	return invoke_psci_fn(PSCI_1_0_FN_PSCI_FEATURES,
+			      psci_func_id, 0, 0);
+}
+
+static u32 psci_0_2_get_version(void)
+{
+	return invoke_psci_fn(PSCI_0_2_FN_PSCI_VERSION, 0, 0, 0);
+}
+
+static void psci_init_system_reset2(void)
+{
+	int ret;
+
+	ret = psci_features(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2));
+
+	if (ret != PSCI_RET_NOT_SUPPORTED)
+		reset2_supported = true;
+}
+
 static int psci_bind(struct udevice *dev)
 {
 	/* No SYSTEM_RESET support for PSCI 0.1 */
@@ -73,6 +109,7 @@ static int psci_bind(struct udevice *dev)
 static int psci_probe(struct udevice *dev)
 {
 	const char *method;
+	u32 ver;
 
 #if defined(CONFIG_ARM64)
 	if (current_el() == 3)
@@ -94,6 +131,16 @@ static int psci_probe(struct udevice *dev)
 		return -EINVAL;
 	}
 
+	ver = psci_0_2_get_version();
+
+	pr_debug("PSCIv%d.%d detected in firmware.\n",
+		 PSCI_VERSION_MAJOR(ver),
+		 PSCI_VERSION_MINOR(ver));
+
+	if (PSCI_VERSION_MAJOR(ver) >= 1) {
+		psci_init_system_reset2();
+	}
+
 	return 0;
 }
 
@@ -141,6 +188,29 @@ void reset_misc(void)
 }
 #endif /* CONFIG_PSCI_RESET */
 
+void psci_sys_reset(u32 type)
+{
+	do_psci_probe();
+
+	if (type == SYSRESET_WARM && reset2_supported) {
+		/*
+		 * reset_type[31] = 0 (architectural)
+		 * reset_type[30:0] = 0 (SYSTEM_WARM_RESET)
+		 * cookie = 0 (ignored by the implementation)
+		 */
+		invoke_psci_fn(PSCI_FN_NATIVE(1_1, SYSTEM_RESET2), 0, 0, 0);
+	} else {
+		invoke_psci_fn(PSCI_0_2_FN_SYSTEM_RESET, 0, 0, 0);
+	}
+}
+
+void psci_sys_poweroff(void)
+{
+	do_psci_probe();
+
+	invoke_psci_fn(PSCI_0_2_FN_SYSTEM_OFF, 0, 0, 0);
+}
+
 #ifdef CONFIG_CMD_POWEROFF
 int do_poweroff(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[])
 {
diff --git a/include/linux/psci.h b/include/linux/psci.h
index 38edde3137..c78c1079a8 100644
--- a/include/linux/psci.h
+++ b/include/linux/psci.h
@@ -118,6 +118,9 @@
 #ifdef CONFIG_ARM_PSCI_FW
 unsigned long invoke_psci_fn(unsigned long a0, unsigned long a1,
 			     unsigned long a2, unsigned long a3);
+void psci_sys_reset(u32 type);
+void psci_sys_poweroff(void);
+
 #else
 static inline unsigned long invoke_psci_fn(unsigned long a0, unsigned long a1,
 					   unsigned long a2, unsigned long a3)
-- 
2.25.1