[PATCH 2/4] MIPS: Enable L2 prefetching for CM >= 2.5

From: Paul Burton
Date: Tue Sep 22 2015 - 13:12:04 EST


On systems with CM 2.5 & beyond there may be L2 prefetch units present
which are not enabled by default. Detect them, configuring & enabling
prefetching when available.

Signed-off-by: Paul Burton <paul.burton@xxxxxxxxxx>
---

arch/mips/include/asm/mips-cm.h | 17 ++++++++++++
arch/mips/mm/sc-mips.c | 61 ++++++++++++++++++++++++++++++++++++++++-
2 files changed, 77 insertions(+), 1 deletion(-)

diff --git a/arch/mips/include/asm/mips-cm.h b/arch/mips/include/asm/mips-cm.h
index d75b75e..36530fd 100644
--- a/arch/mips/include/asm/mips-cm.h
+++ b/arch/mips/include/asm/mips-cm.h
@@ -194,6 +194,8 @@ BUILD_CM_RW(reg3_mask, MIPS_CM_GCB_OFS + 0xc8)
BUILD_CM_R_(gic_status, MIPS_CM_GCB_OFS + 0xd0)
BUILD_CM_R_(cpc_status, MIPS_CM_GCB_OFS + 0xf0)
BUILD_CM_RW(l2_config, MIPS_CM_GCB_OFS + 0x130)
+BUILD_CM_RW(l2_pft_control, MIPS_CM_GCB_OFS + 0x300)
+BUILD_CM_RW(l2_pft_control_b, MIPS_CM_GCB_OFS + 0x308)

/* Core Local & Core Other register accessor functions */
BUILD_CM_Cx_RW(reset_release, 0x00)
@@ -244,6 +246,7 @@ BUILD_CM_Cx_R_(tcid_8_priority, 0x80)
((minor) << CM_GCR_REV_MINOR_SHF))

#define CM_REV_CM2 CM_ENCODE_REV(6, 0)
+#define CM_REV_CM2_5 CM_ENCODE_REV(7, 0)
#define CM_REV_CM3 CM_ENCODE_REV(8, 0)

/* GCR_ERROR_CAUSE register fields */
@@ -316,6 +319,20 @@ BUILD_CM_Cx_R_(tcid_8_priority, 0x80)
#define CM_GCR_L2_CONFIG_ASSOC_SHF 0
#define CM_GCR_L2_CONFIG_ASSOC_MSK (_ULCAST_(0xff) << 0)

+/* GCR_L2_PFT_CONTROL register fields */
+#define CM_GCR_L2_PFT_CONTROL_PAGEMASK_SHF 12
+#define CM_GCR_L2_PFT_CONTROL_PAGEMASK_MSK (_ULCAST_(0xfffff) << 12)
+#define CM_GCR_L2_PFT_CONTROL_PFTEN_SHF 8
+#define CM_GCR_L2_PFT_CONTROL_PFTEN_MSK (_ULCAST_(0x1) << 8)
+#define CM_GCR_L2_PFT_CONTROL_NPFT_SHF 0
+#define CM_GCR_L2_PFT_CONTROL_NPFT_MSK (_ULCAST_(0xff) << 0)
+
+/* GCR_L2_PFT_CONTROL_B register fields */
+#define CM_GCR_L2_PFT_CONTROL_B_CEN_SHF 8
+#define CM_GCR_L2_PFT_CONTROL_B_CEN_MSK (_ULCAST_(0x1) << 8)
+#define CM_GCR_L2_PFT_CONTROL_B_PORTID_SHF 0
+#define CM_GCR_L2_PFT_CONTROL_B_PORTID_MSK (_ULCAST_(0xff) << 0)
+
/* GCR_Cx_COHERENCE register fields */
#define CM_GCR_Cx_COHERENCE_COHDOMAINEN_SHF 0
#define CM_GCR_Cx_COHERENCE_COHDOMAINEN_MSK (_ULCAST_(0xff) << 0)
diff --git a/arch/mips/mm/sc-mips.c b/arch/mips/mm/sc-mips.c
index 53ea839..95cf07c 100644
--- a/arch/mips/mm/sc-mips.c
+++ b/arch/mips/mm/sc-mips.c
@@ -51,11 +51,69 @@ static void mips_sc_disable(void)
/* L2 cache is permanently enabled */
}

+static void mips_sc_prefetch_enable(void)
+{
+ unsigned long pftctl;
+
+ if (mips_cm_revision() < CM_REV_CM2_5)
+ return;
+
+ /*
+ * If there is one or more L2 prefetch unit present then enable
+ * prefetching for both code & data, for all ports.
+ */
+ pftctl = read_gcr_l2_pft_control();
+ if (pftctl & CM_GCR_L2_PFT_CONTROL_NPFT_MSK) {
+ pftctl &= ~CM_GCR_L2_PFT_CONTROL_PAGEMASK_MSK;
+ pftctl |= PAGE_MASK & CM_GCR_L2_PFT_CONTROL_PAGEMASK_MSK;
+ pftctl |= CM_GCR_L2_PFT_CONTROL_PFTEN_MSK;
+ write_gcr_l2_pft_control(pftctl);
+
+ pftctl = read_gcr_l2_pft_control_b();
+ pftctl |= CM_GCR_L2_PFT_CONTROL_B_PORTID_MSK;
+ pftctl |= CM_GCR_L2_PFT_CONTROL_B_CEN_MSK;
+ write_gcr_l2_pft_control_b(pftctl);
+ }
+}
+
+static void mips_sc_prefetch_disable(void)
+{
+ unsigned long pftctl;
+
+ if (mips_cm_revision() < CM_REV_CM2_5)
+ return;
+
+ pftctl = read_gcr_l2_pft_control();
+ pftctl &= ~CM_GCR_L2_PFT_CONTROL_PFTEN_MSK;
+ write_gcr_l2_pft_control(pftctl);
+
+ pftctl = read_gcr_l2_pft_control_b();
+ pftctl &= ~CM_GCR_L2_PFT_CONTROL_B_PORTID_MSK;
+ pftctl &= ~CM_GCR_L2_PFT_CONTROL_B_CEN_MSK;
+ write_gcr_l2_pft_control_b(pftctl);
+}
+
+static bool mips_sc_prefetch_is_enabled(void)
+{
+ unsigned long pftctl;
+
+ if (mips_cm_revision() < CM_REV_CM2_5)
+ return false;
+
+ pftctl = read_gcr_l2_pft_control();
+ if (!(pftctl & CM_GCR_L2_PFT_CONTROL_NPFT_MSK))
+ return false;
+ return !!(pftctl & CM_GCR_L2_PFT_CONTROL_PFTEN_MSK);
+}
+
static struct bcache_ops mips_sc_ops = {
.bc_enable = mips_sc_enable,
.bc_disable = mips_sc_disable,
.bc_wback_inv = mips_sc_wback_inv,
- .bc_inv = mips_sc_inv
+ .bc_inv = mips_sc_inv,
+ .bc_prefetch_enable = mips_sc_prefetch_enable,
+ .bc_prefetch_disable = mips_sc_prefetch_disable,
+ .bc_prefetch_is_enabled = mips_sc_prefetch_is_enabled,
};

/*
@@ -186,6 +244,7 @@ int mips_sc_init(void)
int found = mips_sc_probe();
if (found) {
mips_sc_enable();
+ mips_sc_prefetch_enable();
bcops = &mips_sc_ops;
}
return found;
--
2.5.3

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/