[PATCH v2 12/20] mips: MAAR: Add XPA mode support

Sergey.Semin
2020-05-06T17:45:09Z

From: Serge Semin <Sergey.Semin@baikalelectronics.ru>

When XPA mode is enabled the normally 32-bits MAAR pair registers
are extended to be of 64-bits width as in pure 64-bits MIPS
architecture. In this case the MAAR registers can enable the
speculative loads/stores for addresses of up to 39-bits width.
But in this case the process of the MAAR initialization changes a bit.
The upper 32-bits of the registers are supposed to be accessed by mean
of the dedicated instructions mfhc0/mthc0 and there is a CP0.MAAR.VH
bit which should be set together with CP0.MAAR.VL as indication
of the boundary validity. All of these peculiarities were taken into
account in this commit so the speculative loads/stores would work
when XPA mode is enabled.

Co-developed-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: linux-pm@vger.kernel.org
Cc: devicetree@vger.kernel.org
---
arch/mips/include/asm/maar.h | 17 +++++++++++++++--
arch/mips/include/asm/mipsregs.h | 10 ++++++++++
arch/mips/mm/init.c | 8 +++++++-
3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/arch/mips/include/asm/maar.h b/arch/mips/include/asm/maar.h
index 6908b93c4ff9..99f1c3e4b11f 100644
--- a/arch/mips/include/asm/maar.h
+++ b/arch/mips/include/asm/maar.h
@@ -32,7 +32,7 @@ unsigned platform_maar_init(unsigned num_pairs);
* @upper: The highest address that the MAAR pair will affect. Must be
* aligned to one byte before a 2^16 byte boundary.
* @attrs: The accessibility attributes to program, eg. MIPS_MAAR_S. The
- * MIPS_MAAR_VL attribute will automatically be set.
+ * MIPS_MAAR_VL/MIPS_MAAR_VH attributes will automatically be set.
*
* Program the pair of MAAR registers specified by idx to apply the attributes
* specified by attrs to the range of addresses from lower to higher.
@@ -48,17 +48,30 @@ static inline void write_maar_pair(unsigned idx, phys_addr_t lower,
/* Automatically set MIPS_MAAR_VL */
attrs |= MIPS_MAAR_VL;

- /* Write the upper address & attributes (only MIPS_MAAR_VL matters) */
+ /*
+ * Write the upper address & attributes (both MIPS_MAAR_VL and
+ * MIPS_MAAR_VH matter)
+ */
write_c0_maari(idx << 1);
back_to_back_c0_hazard();
write_c0_maar(((upper >> 4) & MIPS_MAAR_ADDR) | attrs);
back_to_back_c0_hazard();
+#ifdef CONFIG_XPA
+ upper >>= MIPS_MAARX_ADDR_SHIFT;
+ writex_c0_maar(((upper >> 4) & MIPS_MAARX_ADDR) | MIPS_MAARX_VH);
+ back_to_back_c0_hazard();
+#endif

/* Write the lower address & attributes */
write_c0_maari((idx << 1) | 0x1);
back_to_back_c0_hazard();
write_c0_maar((lower >> 4) | attrs);
back_to_back_c0_hazard();
+#ifdef CONFIG_XPA
+ lower >>= MIPS_MAARX_ADDR_SHIFT;
+ writex_c0_maar(((lower >> 4) & MIPS_MAARX_ADDR) | MIPS_MAARX_VH);
+ back_to_back_c0_hazard();
+#endif
}

/**
diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index 165f6318d861..aa8599962ea3 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -779,6 +779,14 @@
#define MIPS_MAAR_ADDR_SHIFT 12
#define MIPS_MAAR_S (_ULCAST_(1) << 1)
#define MIPS_MAAR_VL (_ULCAST_(1) << 0)
+#ifdef CONFIG_XPA
+#define MIPS_MAAR_V (MIPS_MAAR_VH | MIPS_MAAR_VL)
+#else
+#define MIPS_MAAR_V MIPS_MAAR_VL
+#endif
+#define MIPS_MAARX_VH (_ULCAST_(1) << 31)
+#define MIPS_MAARX_ADDR 0xF
+#define MIPS_MAARX_ADDR_SHIFT 32

/* MAARI bit definitions */
#define MIPS_MAARI_INDEX (_ULCAST_(0x3f) << 0)
@@ -1739,6 +1747,8 @@ do { \
#define write_c0_lladdr(val) __write_ulong_c0_register($17, 0, val)
#define read_c0_maar() __read_ulong_c0_register($17, 1)
#define write_c0_maar(val) __write_ulong_c0_register($17, 1, val)
+#define readx_c0_maar() __readx_32bit_c0_register($17, 1)
+#define writex_c0_maar(val) __writex_32bit_c0_register($17, 1, val)
#define read_c0_maari() __read_32bit_c0_register($17, 2)
#define write_c0_maari(val) __write_32bit_c0_register($17, 2, val)

diff --git a/arch/mips/mm/init.c b/arch/mips/mm/init.c
index 79684000de0e..620ebfa45ec1 100644
--- a/arch/mips/mm/init.c
+++ b/arch/mips/mm/init.c
@@ -358,17 +358,23 @@ void maar_init(void)
write_c0_maari(i);
back_to_back_c0_hazard();
upper = read_c0_maar();
+#ifdef CONFIG_XPA
+ upper |= (phys_addr_t)readx_c0_maar() << MIPS_MAARX_ADDR_SHIFT;
+#endif

write_c0_maari(i + 1);
back_to_back_c0_hazard();
lower = read_c0_maar();
+#ifdef CONFIG_XPA
+ lower |= (phys_addr_t)readx_c0_maar() << MIPS_MAARX_ADDR_SHIFT;
+#endif

attr = lower & upper;
lower = (lower & MIPS_MAAR_ADDR) << 4;
upper = ((upper & MIPS_MAAR_ADDR) << 4) | 0xffff;

pr_info(" [%d]: ", i / 2);
- if (!(attr & MIPS_MAAR_VL)) {
+ if ((attr & MIPS_MAAR_V) != MIPS_MAAR_V) {
pr_cont("disabled\n");
continue;
}
--
2.25.1