linux-kernel - [PATCH 7/8] riscv: Use pgtable_l4_enabled to output mmu type in cpuinfo

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Date:   Sun, 24 May 2020 05:10:07 -0400
From:   Alexandre Ghiti <alex@...ti.fr>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Zong Li <zong.li@...ive.com>, Anup Patel <anup@...infault.org>,
        Christoph Hellwig <hch@....de>,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org
Cc:     Alexandre Ghiti <alex@...ti.fr>,
        Palmer Dabbelt <palmerdabbelt@...gle.com>
Subject: [PATCH 7/8] riscv: Use pgtable_l4_enabled to output mmu type in cpuinfo

Now that the mmu type is determined at runtime using SATP
characteristic, use the global variable pgtable_l4_enabled to output
mmu type of the processor through /proc/cpuinfo instead of relying on
device tree infos.

Signed-off-by: Alexandre Ghiti <alex@...ti.fr>
Reviewed-by: Anup Patel <anup@...infault.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@...gle.com>
---
 arch/riscv/boot/dts/sifive/fu540-c000.dtsi |  4 ----
 arch/riscv/kernel/cpu.c                    | 24 ++++++++++++----------
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/arch/riscv/boot/dts/sifive/fu540-c000.dtsi b/arch/riscv/boot/dts/sifive/fu540-c000.dtsi
index 7db861053483..6138590a2229 100644
--- a/arch/riscv/boot/dts/sifive/fu540-c000.dtsi
+++ b/arch/riscv/boot/dts/sifive/fu540-c000.dtsi
@@ -50,7 +50,6 @@
 			i-cache-size = <32768>;
 			i-tlb-sets = <1>;
 			i-tlb-size = <32>;
-			mmu-type = "riscv,sv39";
 			reg = <1>;
 			riscv,isa = "rv64imafdc";
 			tlb-split;
@@ -74,7 +73,6 @@
 			i-cache-size = <32768>;
 			i-tlb-sets = <1>;
 			i-tlb-size = <32>;
-			mmu-type = "riscv,sv39";
 			reg = <2>;
 			riscv,isa = "rv64imafdc";
 			tlb-split;
@@ -98,7 +96,6 @@
 			i-cache-size = <32768>;
 			i-tlb-sets = <1>;
 			i-tlb-size = <32>;
-			mmu-type = "riscv,sv39";
 			reg = <3>;
 			riscv,isa = "rv64imafdc";
 			tlb-split;
@@ -122,7 +119,6 @@
 			i-cache-size = <32768>;
 			i-tlb-sets = <1>;
 			i-tlb-size = <32>;
-			mmu-type = "riscv,sv39";
 			reg = <4>;
 			riscv,isa = "rv64imafdc";
 			tlb-split;
diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c
index 40a3c442ac5f..38a699b997a8 100644
--- a/arch/riscv/kernel/cpu.c
+++ b/arch/riscv/kernel/cpu.c
@@ -8,6 +8,8 @@
 #include <linux/of.h>
 #include <asm/smp.h>
 
+extern bool pgtable_l4_enabled;
+
 /*
  * Returns the hart ID of the given device tree node, or -ENODEV if the node
  * isn't an enabled and valid RISC-V hart node.
@@ -54,18 +56,19 @@ static void print_isa(struct seq_file *f, const char *isa)
 	seq_puts(f, "\n");
 }
 
-static void print_mmu(struct seq_file *f, const char *mmu_type)
+static void print_mmu(struct seq_file *f)
 {
+	char sv_type[16];
+
 #if defined(CONFIG_32BIT)
-	if (strcmp(mmu_type, "riscv,sv32") != 0)
-		return;
+	strncpy(sv_type, "sv32", 5);
 #elif defined(CONFIG_64BIT)
-	if (strcmp(mmu_type, "riscv,sv39") != 0 &&
-	    strcmp(mmu_type, "riscv,sv48") != 0)
-		return;
+	if (pgtable_l4_enabled)
+		strncpy(sv_type, "sv48", 5);
+	else
+		strncpy(sv_type, "sv39", 5);
 #endif
-
-	seq_printf(f, "mmu\t\t: %s\n", mmu_type+6);
+	seq_printf(f, "mmu\t\t: %s\n", sv_type);
 }
 
 static void *c_start(struct seq_file *m, loff_t *pos)
@@ -90,14 +93,13 @@ static int c_show(struct seq_file *m, void *v)
 {
 	unsigned long cpu_id = (unsigned long)v - 1;
 	struct device_node *node = of_get_cpu_node(cpu_id, NULL);
-	const char *compat, *isa, *mmu;
+	const char *compat, *isa;
 
 	seq_printf(m, "processor\t: %lu\n", cpu_id);
 	seq_printf(m, "hart\t\t: %lu\n", cpuid_to_hartid_map(cpu_id));
 	if (!of_property_read_string(node, "riscv,isa", &isa))
 		print_isa(m, isa);
-	if (!of_property_read_string(node, "mmu-type", &mmu))
-		print_mmu(m, mmu);
+	print_mmu(m);
 	if (!of_property_read_string(node, "compatible", &compat)
 	    && strcmp(compat, "riscv"))
 		seq_printf(m, "uarch\t\t: %s\n", compat);
-- 
2.20.1