linux-kernel - [PATCH] ARM: bcmbca: add VFP and NEON fixup for bcm6846 SoC

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Message-Id: <20220525003509.2812-1-william.zhang@broadcom.com>
Date:   Tue, 24 May 2022 17:35:09 -0700
From:   William Zhang <william.zhang@...adcom.com>
To:     Linux ARM List <linux-arm-kernel@...ts.infradead.org>
Cc:     joel.peshkin@...adcom.com, florian.fainelli@...adcom.com,
        dan.beygelman@...adcom.com, anand.gore@...adcom.com,
        kursad.oney@...adcom.com, samyon.furman@...adcom.com,
        tomer.yacoby@...adcom.com, philippe.reynes@...tathome.com,
        William Zhang <william.zhang@...adcom.com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Ray Jui <rjui@...adcom.com>,
        Russell King <linux@...linux.org.uk>,
        Scott Branden <sbranden@...adcom.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] ARM: bcmbca: add VFP and NEON fixup for bcm6846 SoC

BCM6846 SoC only has VFP and NEON support on core 0. So kernel VPF/NEON
support is disabled in this chip. Add this fixup to manually turn on
VFP/NEON in case userspace app need to access them on core 0.

Signed-off-by: William Zhang <william.zhang@...adcom.com>

---

 arch/arm/mach-bcm/Makefile |  5 ++++
 arch/arm/mach-bcm/bcmbca.c | 54 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100644 arch/arm/mach-bcm/bcmbca.c

diff --git a/arch/arm/mach-bcm/Makefile b/arch/arm/mach-bcm/Makefile
index b2394ddb0558..137b24b52139 100644
--- a/arch/arm/mach-bcm/Makefile
+++ b/arch/arm/mach-bcm/Makefile
@@ -68,3 +68,8 @@ CFLAGS_platsmp-brcmstb.o	+= -march=armv7-a
 obj-y				+= brcmstb.o
 obj-$(CONFIG_SMP)		+= platsmp-brcmstb.o
 endif
+
+# BCMBCA
+ifeq ($(CONFIG_ARCH_BCMBCA),y)
+obj-y				+= bcmbca.o
+endif
diff --git a/arch/arm/mach-bcm/bcmbca.c b/arch/arm/mach-bcm/bcmbca.c
new file mode 100644
index 000000000000..6fcdfe0b94c1
--- /dev/null
+++ b/arch/arm/mach-bcm/bcmbca.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022 Broadcom Ltd
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation version 2.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/smp.h>
+#include <asm/mach/arch.h>
+#include <asm/vfp.h>
+#include <asm/cp15.h>
+
+#include "../vfp/vfpinstr.h"
+
+/*
+ * In some low end BCA chips, only core 0 has VPF/NEON support. Kernel VPF
+ * NEON are disabled on these platforms. Add this fixup to enable VFP/NEON
+ * on core 0 manually in case some user app need to access vfp/neon on core 0
+ */
+static void __init neon_enable(void *data)
+{
+	u32 access, fpexc;
+	(void)data;
+
+	/* Enable full access to VFP (cp10 and cp11) */
+	access = get_copro_access();
+	set_copro_access(access | CPACC_FULL(10) | CPACC_FULL(11));
+
+	/* enable NEON and VFP extension */
+	fpexc = fmrx(FPEXC);
+	fmxr(FPEXC, fpexc | FPEXC_EN);
+}
+
+static void __init bcmbca_neon_fixup(void)
+{
+	smp_call_function_single(0, neon_enable, NULL, 1);
+}
+
+static const char *const bcmbca_match[] __initconst = {
+	"brcm,bcm6846",
+	NULL
+};
+
+DT_MACHINE_START(BCMBCA, "Broadcom BCMBCA SoC")
+	.dt_compat		= bcmbca_match,
+	.init_late		= bcmbca_neon_fixup,
+MACHINE_END
-- 
2.17.1


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