x86: quark: Configure MTRR to enable cache

Quark SoC does not support MSR MTRRs. Fixed and variable range MTRRs
are accessed indirectly via the message port and not the traditional
MSR mechanism. Only UC, WT and WB cache types are supported.

We configure all the fixed range MTRRs with common values (VGA RAM
as UC, others as WB) and 3 variable range MTRRs for ROM/eSRAM/RAM as
WB, which significantly improves the boot time performance.

With this commit, it takes only 2 seconds for U-Boot to boot to shell
on Intel Galileo board. Previously it took about 6 seconds.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>
Tested-by: Simon Glass <sjg@chromium.org>

2 files changed, 67 insertions, 0 deletions

diff --git a/arch/x86/cpu/quark/dram.c b/arch/x86/cpu/quark/dram.c
index 9cac846c69..1b89376387 100644
--- a/arch/x86/cpu/quark/dram.c
+++ b/arch/x86/cpu/quark/dram.c
@@ -7,8 +7,10 @@
 #include <common.h>
 #include <errno.h>
 #include <fdtdec.h>
+#include <asm/mtrr.h>
 #include <asm/post.h>
 #include <asm/arch/mrc.h>
+#include <asm/arch/msg_port.h>
 #include <asm/arch/quark.h>
 
 DECLARE_GLOBAL_DATA_PTR;
@@ -111,6 +113,14 @@ int dram_init(void)
 	gd->ram_size = mrc_params.mem_size;
 	post_code(POST_DRAM);
 
+	/* variable range MTRR#2: RAM area */
+	disable_caches();
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_VAR_PHYBASE(MTRR_VAR_RAM),
+		       0 | MTRR_TYPE_WRBACK);
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_VAR_PHYMASK(MTRR_VAR_RAM),
+		       (~(gd->ram_size - 1)) | MTRR_PHYS_MASK_VALID);
+	enable_caches();
+
 	return 0;
 }
 
diff --git a/arch/x86/cpu/quark/quark.c b/arch/x86/cpu/quark/quark.c
index 8b78a867ef..77d644a491 100644
--- a/arch/x86/cpu/quark/quark.c
+++ b/arch/x86/cpu/quark/quark.c
@@ -8,6 +8,7 @@
 #include <mmc.h>
 #include <asm/io.h>
 #include <asm/irq.h>
+#include <asm/mtrr.h>
 #include <asm/pci.h>
 #include <asm/post.h>
 #include <asm/processor.h>
@@ -34,6 +35,55 @@ static void unprotect_spi_flash(void)
 	qrk_pci_write_config_dword(QUARK_LEGACY_BRIDGE, 0xd8, bc);
 }
 
+static void quark_setup_mtrr(void)
+{
+	u32 base, mask;
+	int i;
+
+	disable_caches();
+
+	/* mark the VGA RAM area as uncacheable */
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_FIX_16K_A0000,
+		       MTRR_FIX_TYPE(MTRR_TYPE_UNCACHEABLE));
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_FIX_16K_B0000,
+		       MTRR_FIX_TYPE(MTRR_TYPE_UNCACHEABLE));
+
+	/* mark other fixed range areas as cacheable */
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_FIX_64K_00000,
+		       MTRR_FIX_TYPE(MTRR_TYPE_WRBACK));
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_FIX_64K_40000,
+		       MTRR_FIX_TYPE(MTRR_TYPE_WRBACK));
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_FIX_16K_80000,
+		       MTRR_FIX_TYPE(MTRR_TYPE_WRBACK));
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_FIX_16K_90000,
+		       MTRR_FIX_TYPE(MTRR_TYPE_WRBACK));
+	for (i = MTRR_FIX_4K_C0000; i <= MTRR_FIX_4K_FC000; i++)
+		msg_port_write(MSG_PORT_HOST_BRIDGE, i,
+			       MTRR_FIX_TYPE(MTRR_TYPE_WRBACK));
+
+	/* variable range MTRR#0: ROM area */
+	mask = ~(CONFIG_SYS_MONITOR_LEN - 1);
+	base = CONFIG_SYS_TEXT_BASE & mask;
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_VAR_PHYBASE(MTRR_VAR_ROM),
+		       base | MTRR_TYPE_WRBACK);
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_VAR_PHYMASK(MTRR_VAR_ROM),
+		       mask | MTRR_PHYS_MASK_VALID);
+
+	/* variable range MTRR#1: eSRAM area */
+	mask = ~(ESRAM_SIZE - 1);
+	base = CONFIG_ESRAM_BASE & mask;
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_VAR_PHYBASE(MTRR_VAR_ESRAM),
+		       base | MTRR_TYPE_WRBACK);
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_VAR_PHYMASK(MTRR_VAR_ESRAM),
+		       mask | MTRR_PHYS_MASK_VALID);
+
+	/* enable both variable and fixed range MTRRs */
+	msg_port_write(MSG_PORT_HOST_BRIDGE, MTRR_DEF_TYPE,
+		       MTRR_DEF_TYPE_EN | MTRR_DEF_TYPE_FIX_EN);
+
+	enable_caches();
+}
+
 static void quark_setup_bars(void)
 {
 	/* GPIO - D31:F0:R44h */
@@ -191,6 +241,13 @@ int arch_cpu_init(void)
 		return ret;
 
 	/*
+	 * Quark SoC does not support MSR MTRRs. Fixed and variable range MTRRs
+	 * are accessed indirectly via the message port and not the traditional
+	 * MSR mechanism. Only UC, WT and WB cache types are supported.
+	 */
+	quark_setup_mtrr();
+
+	/*
 	 * Quark SoC has some non-standard BARs (excluding PCI standard BARs)
 	 * which need be initialized with suggested values
 	 */