[RFC PATCH 4/6] firmware: arm_sdei: use SMCCC v1.0 helper functions

[Etienne Carriere]

Change Arm SDEI firmware driver to use SMCCC v1.0 helper functions.

Functional changes are Arm SDEI firmware driver can find appropriate
set conduit if it does not define one but another device has set
the kernel conduit for SMCCC calls.

Other functional changes are the trace messages emitted at device
probe time that now dev_*() traces instead of pr_*() traces.

Signed-off-by: Etienne Carriere <etienne.carriere@xxxxxxxxxx>
---
 drivers/firmware/arm_sdei.c | 79 +++++++++++++------------------------
 1 file changed, 27 insertions(+), 52 deletions(-)

diff --git a/drivers/firmware/arm_sdei.c b/drivers/firmware/arm_sdei.c
index 334c8be0c11f..92f8077e0bde 100644
--- a/drivers/firmware/arm_sdei.c
+++ b/drivers/firmware/arm_sdei.c
@@ -34,12 +34,9 @@
 #include <linux/uaccess.h>
 
 /*
- * The call to use to reach the firmware.
+ * The SMCCC cnduit for the call to use to reach the firmware.
  */
-static asmlinkage void (*sdei_firmware_call)(unsigned long function_id,
-		      unsigned long arg0, unsigned long arg1,
-		      unsigned long arg2, unsigned long arg3,
-		      unsigned long arg4, struct arm_smccc_res *res);
+static enum arm_smccc_conduit sdei_firmware_call_conduit;
 
 /* entry point from firmware to arch asm code */
 static unsigned long sdei_entry_point;
@@ -144,14 +141,14 @@ static int invoke_sdei_fn(unsigned long function_id, unsigned long arg0,
 	int err = 0;
 	struct arm_smccc_res res;
 
-	if (sdei_firmware_call) {
+	if (sdei_firmware_call_conduit != SMCCC_CONDUIT_NONE) {
 		sdei_firmware_call(function_id, arg0, arg1, arg2, arg3, arg4,
 				   &res);
 		if (sdei_is_err(&res))
 			err = sdei_to_linux_errno(res.a0);
 	} else {
 		/*
-		 * !sdei_firmware_call means we failed to probe or called
+		 * No SMCCC conduit means we failed to probe or called
 		 * sdei_mark_interface_broken(). -EIO is not an error returned
 		 * by sdei_to_linux_errno() and is used to suppress messages
 		 * from this driver.
@@ -364,7 +361,7 @@ static void sdei_mark_interface_broken(void)
 {
 	pr_err("disabling SDEI firmware interface\n");
 	on_each_cpu(&_ipi_mask_cpu, NULL, true);
-	sdei_firmware_call = NULL;
+	sdei_firmware_call_conduit = SMCCC_CONDUIT_NONE;
 }
 
 static int sdei_platform_reset(void)
@@ -874,23 +871,19 @@ static struct notifier_block sdei_reboot_nb = {
 	.notifier_call = sdei_reboot_notifier,
 };
 
-static void sdei_smccc_smc(unsigned long function_id,
-			   unsigned long arg0, unsigned long arg1,
-			   unsigned long arg2, unsigned long arg3,
-			   unsigned long arg4, struct arm_smccc_res *res)
-{
-	arm_smccc_smc(function_id, arg0, arg1, arg2, arg3, arg4, 0, 0, res);
-}
-NOKPROBE_SYMBOL(sdei_smccc_smc);
 
-static void sdei_smccc_hvc(unsigned long function_id,
-			   unsigned long arg0, unsigned long arg1,
-			   unsigned long arg2, unsigned long arg3,
-			   unsigned long arg4, struct arm_smccc_res *res)
+static asmlinkage void sdei_firmware_call(unsigned long function_id,
+					  unsigned long arg0,
+					  unsigned long arg1,
+					  unsigned long arg2,
+					  unsigned long arg3,
+					  unsigned long arg4,
+					  struct arm_smccc_res *res)
 {
-	arm_smccc_hvc(function_id, arg0, arg1, arg2, arg3, arg4, 0, 0, res);
+	arm_smccc_1_0_invoke(function_id, arg0, arg1, arg2, arg3, arg4,
+			     0, 0, res);
 }
-NOKPROBE_SYMBOL(sdei_smccc_hvc);
+NOKPROBE_SYMBOL(sdei_firmware_call);
 
 int sdei_register_ghes(struct ghes *ghes, sdei_event_callback *normal_cb,
 		       sdei_event_callback *critical_cb)
@@ -959,48 +952,30 @@ int sdei_unregister_ghes(struct ghes *ghes)
 	return err;
 }
 
-static int sdei_get_conduit(struct platform_device *pdev)
+static enum arm_smccc_conduit sdei_get_conduit(struct platform_device *pdev)
 {
-	const char *method;
-	struct device_node *np = pdev->dev.of_node;
-
-	sdei_firmware_call = NULL;
-	if (np) {
-		if (of_property_read_string(np, "method", &method)) {
-			pr_warn("missing \"method\" property\n");
-			return SMCCC_CONDUIT_NONE;
-		}
-
-		if (!strcmp("hvc", method)) {
-			sdei_firmware_call = &sdei_smccc_hvc;
-			return SMCCC_CONDUIT_HVC;
-		} else if (!strcmp("smc", method)) {
-			sdei_firmware_call = &sdei_smccc_smc;
-			return SMCCC_CONDUIT_SMC;
-		}
-
-		pr_warn("invalid \"method\" property: %s\n", method);
+	if (pdev->dev.of_node) {
+		devm_arm_smccc_1_0_set_conduit(pdev->dev);
 	} else if (IS_ENABLED(CONFIG_ACPI) && !acpi_disabled) {
-		if (acpi_psci_use_hvc()) {
-			sdei_firmware_call = &sdei_smccc_hvc;
-			return SMCCC_CONDUIT_HVC;
-		} else {
-			sdei_firmware_call = &sdei_smccc_smc;
-			return SMCCC_CONDUIT_SMC;
-		}
+		if (acpi_psci_use_hvc())
+			arm_smccc_1_0_set_conduit(SMCCC_CONDUIT_HVC);
+		else
+			arm_smccc_1_0_set_conduit(SMCCC_CONDUIT_SMC);
 	}
 
-	return SMCCC_CONDUIT_NONE;
+	sdei_firmware_call_conduit = arm_smccc_1_0_get_conduit();
+
+	return sdei_firmware_call_conduit;
 }
 
 static int sdei_probe(struct platform_device *pdev)
 {
 	int err;
 	u64 ver = 0;
-	int conduit;
+	enum arm_smccc_conduit conduit;
 
 	conduit = sdei_get_conduit(pdev);
-	if (!sdei_firmware_call)
+	if (conduit == SMCCC_CONDUIT_NONE)
 		return 0;
 
 	err = sdei_api_get_version(&ver);
-- 
2.17.1