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ARM: l2c: add automatic enable of early BRESP 

The AXI bus protocol requires that a write response should only be
sent back to the master when the last write has been accepted.  Early
BRESP allows the L2C-310 to send the write response as soon as the
store buffer accepts the write address.

Cortex-A9 processors can signal to the L2C-310 that they wish to be
notified early, and if this optimisation is enabled, the L2C-310 can
signal an early write response.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
hifive-unleashed-5.1
Russell King 2014-03-19 15:39:09 +00:00
parent ddf7d79bc7
commit 4374d64933
1 changed files with 22 additions and 3 deletions
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25
arch/arm/mm/cache-l2x0.c
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@ -24,6 +24,7 @@
#include <linux/of_address.h>
#include <asm/cacheflush.h>
#include <asm/cputype.h>
#include <asm/hardware/cache-l2x0.h>
#include "cache-tauros3.h"
#include "cache-aurora-l2.h"
@ -638,6 +639,24 @@ static void l2c310_resume(void)
}
}
static void __init l2c310_enable(void __iomem *base, u32 aux, unsigned num_lock)
{
unsigned rev = readl_relaxed(base + L2X0_CACHE_ID) & L2X0_CACHE_ID_PART_MASK;
bool cortex_a9 = read_cpuid_part_number() == ARM_CPU_PART_CORTEX_A9;
if (rev >= L310_CACHE_ID_RTL_R2P0) {
if (cortex_a9) {
aux |= L310_AUX_CTRL_EARLY_BRESP;
pr_info("L2C-310 enabling early BRESP for Cortex-A9\n");
} else if (aux & L310_AUX_CTRL_EARLY_BRESP) {
pr_warn("L2C-310 early BRESP only supported with Cortex-A9\n");
aux &= ~L310_AUX_CTRL_EARLY_BRESP;
}
}
l2c_enable(base, aux, num_lock);
}
static void __init l2c310_fixup(void __iomem *base, u32 cache_id,
struct outer_cache_fns *fns)
{
@ -699,7 +718,7 @@ static const struct l2c_init_data l2c310_init_fns __initconst = {
.type = "L2C-310",
.way_size_0 = SZ_8K,
.num_lock = 8,
.enable = l2c_enable,
.enable = l2c310_enable,
.fixup = l2c310_fixup,
.save = l2c310_save,
.outer_cache = {
@ -940,7 +959,7 @@ static const struct l2c_init_data of_l2c310_data __initconst = {
.way_size_0 = SZ_8K,
.num_lock = 8,
.of_parse = l2c310_of_parse,
.enable = l2c_enable,
.enable = l2c310_enable,
.fixup = l2c310_fixup,
.save = l2c310_save,
.outer_cache = {
@ -1289,7 +1308,7 @@ static const struct l2c_init_data of_bcm_l2x0_data __initconst = {
.way_size_0 = SZ_8K,
.num_lock = 8,
.of_parse = l2c310_of_parse,
.enable = l2c_enable,
.enable = l2c310_enable,
.save = l2c310_save,
.outer_cache = {
.inv_range = bcm_inv_range,