riscv: add option to wait for ack from secondary harts in smp functions

Add a wait option to smp_call_function() to wait for the secondary harts to acknowledge the call-function request. The request is considered to be acknowledged once each secondary hart has cleared the corresponding IPI. As part of the call-function request, the secondary harts invalidate the instruction cache after clearing the IPI. This adds a delay between acknowledgment (clear IPI) and fulfillment (call function) of the request. We want to use the acknowledgment to be able to judge when the request has been completed. Remove the delay by clearing the IPI after cache invalidation and just before calling the function from the request. Signed-off-by: Lukas Auer <[email protected]> Reviewed-by: Rick Chen <[email protected]> Tested-by: Rick Chen <[email protected]> Reviewed-by: Anup Patel <[email protected]>
imaami · Dec 10, 2019 · 90ae281 · 90ae281
1 parent 8b3e97b
commit 90ae281
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Showing 6 changed files with 29 additions and 13 deletions.
diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
@@ -197,6 +197,7 @@ spl_secondary_hart_stack_gd_setup:
 	la	a0, secondary_hart_relocate
 	mv	a1, s0
 	mv	a2, s0
+	mv	a3, zero
 	jal	smp_call_function
 
 	/* hang if relocation of secondary harts has failed */
@@ -337,6 +338,7 @@ relocate_secondary_harts:
 
 	mv	a1, s2
 	mv	a2, s3
+	mv	a3, zero
 	jal	smp_call_function
 
 	/* hang if relocation of secondary harts has failed */

diff --git a/arch/riscv/include/asm/smp.h b/arch/riscv/include/asm/smp.h
@@ -46,8 +46,9 @@ void handle_ipi(ulong hart);
  * @addr: Address of function
  * @arg0: First argument of function
  * @arg1: Second argument of function
+ * @wait: Wait for harts to acknowledge request
  * @return 0 if OK, -ve on error
  */
-int smp_call_function(ulong addr, ulong arg0, ulong arg1);
+int smp_call_function(ulong addr, ulong arg0, ulong arg1, int wait);
 
 #endif
diff --git a/arch/riscv/lib/bootm.c b/arch/riscv/lib/bootm.c
@@ -99,7 +99,7 @@ static void boot_jump_linux(bootm_headers_t *images, int flag)
 		if (IMAGE_ENABLE_OF_LIBFDT && images->ft_len) {
 #ifdef CONFIG_SMP
 			ret = smp_call_function(images->ep,
-						(ulong)images->ft_addr, 0);
+						(ulong)images->ft_addr, 0, 0);
 			if (ret)
 				hang();
 #endif

diff --git a/arch/riscv/lib/smp.c b/arch/riscv/lib/smp.c
@@ -44,11 +44,11 @@ extern int riscv_clear_ipi(int hart);
  */
 extern int riscv_get_ipi(int hart, int *pending);
 
-static int send_ipi_many(struct ipi_data *ipi)
+static int send_ipi_many(struct ipi_data *ipi, int wait)
 {
 	ofnode node, cpus;
 	u32 reg;
-	int ret;
+	int ret, pending;
 
 	cpus = ofnode_path("/cpus");
 	if (!ofnode_valid(cpus)) {
@@ -91,6 +91,15 @@ static int send_ipi_many(struct ipi_data *ipi)
 			pr_err("Cannot send IPI to hart %d\n", reg);
 			return ret;
 		}
+
+		if (wait) {
+			pending = 1;
+			while (pending) {
+				ret = riscv_get_ipi(reg, &pending);
+				if (ret)
+					return ret;
+			}
+		}
 	}
 
 	return 0;
@@ -104,21 +113,25 @@ void handle_ipi(ulong hart)
 	if (hart >= CONFIG_NR_CPUS)
 		return;
 
+	__smp_mb();
+
+	smp_function = (void (*)(ulong, ulong, ulong))gd->arch.ipi[hart].addr;
+	invalidate_icache_all();
+
+	/*
+	 * Clear the IPI to acknowledge the request before jumping to the
+	 * requested function.
+	 */
 	ret = riscv_clear_ipi(hart);
 	if (ret) {
 		pr_err("Cannot clear IPI of hart %ld\n", hart);
 		return;
 	}
 
-	__smp_mb();
-
-	smp_function = (void (*)(ulong, ulong, ulong))gd->arch.ipi[hart].addr;
-	invalidate_icache_all();
-
 	smp_function(hart, gd->arch.ipi[hart].arg0, gd->arch.ipi[hart].arg1);
 }
 
-int smp_call_function(ulong addr, ulong arg0, ulong arg1)
+int smp_call_function(ulong addr, ulong arg0, ulong arg1, int wait)
 {
 	int ret = 0;
 	struct ipi_data ipi;
@@ -127,7 +140,7 @@ int smp_call_function(ulong addr, ulong arg0, ulong arg1)
 	ipi.arg0 = arg0;
 	ipi.arg1 = arg1;
 
-	ret = send_ipi_many(&ipi);
+	ret = send_ipi_many(&ipi, wait);
 
 	return ret;
 }
diff --git a/arch/riscv/lib/spl.c b/arch/riscv/lib/spl.c
@@ -41,7 +41,7 @@ void __noreturn jump_to_image_no_args(struct spl_image_info *spl_image)
 
 	debug("image entry point: 0x%lX\n", spl_image->entry_point);
 #ifdef CONFIG_SMP
-	ret = smp_call_function(spl_image->entry_point, (ulong)fdt_blob, 0);
+	ret = smp_call_function(spl_image->entry_point, (ulong)fdt_blob, 0, 0);
 	if (ret)
 		hang();
 #endif

diff --git a/common/spl/spl_opensbi.c b/common/spl/spl_opensbi.c
@@ -78,7 +78,7 @@ void spl_invoke_opensbi(struct spl_image_info *spl_image)
 #ifdef CONFIG_SMP
 	ret = smp_call_function((ulong)spl_image->entry_point,
 				(ulong)spl_image->fdt_addr,
-				(ulong)&opensbi_info);
+				(ulong)&opensbi_info, 0);
 	if (ret)
 		hang();
 #endif