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ARM: mvebu: implement Armada 375 coherency workaround

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The early revisions of Armada 375 SOCs (Z1 stepping) have a bug in the
I/O coherency unit that prevents using the normal method for the I/O
coherency barrier. The recommended workaround is to use a XOR memset
transfer to act as the I/O coherency barrier.

This involves "borrowing" a XOR engine, which gets disabled in the
Device Tree so the normal XOR driver doesn't use it.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Link: https://lkml.kernel.org/r/1397483228-25625-8-git-send-email-thomas.petazzoni@free-electrons.com
Signed-off-by: Jason Cooper <jason@lakedaemon.net>
This commit is contained in:
Thomas Petazzoni 2014-04-14 15:47:05 +02:00 committed by Jason Cooper
parent 77fa4b9ab0
commit 5ab5afd8ba
1 changed files with 165 additions and 3 deletions
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168
arch/arm/mach-mvebu/coherency.c
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@ -17,6 +17,8 @@
* supplies basic routines for configuring and controlling hardware coherency
*/
#define pr_fmt(fmt) "mvebu-coherency: " fmt
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/of_address.h>
@ -24,6 +26,9 @@
#include <linux/smp.h>
#include <linux/dma-mapping.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/mbus.h>
#include <linux/clk.h>
#include <asm/smp_plat.h>
#include <asm/cacheflush.h>
#include "armada-370-xp.h"
@ -66,8 +71,157 @@ int set_cpu_coherent(unsigned int hw_cpu_id, int smp_group_id)
return ll_set_cpu_coherent(coherency_base, hw_cpu_id);
}
/*
* The below code implements the I/O coherency workaround on Armada
* 375. This workaround consists in using the two channels of the
* first XOR engine to trigger a XOR transaction that serves as the
* I/O coherency barrier.
*/
static void __iomem *xor_base, *xor_high_base;
static dma_addr_t coherency_wa_buf_phys[CONFIG_NR_CPUS];
static void *coherency_wa_buf[CONFIG_NR_CPUS];
static bool coherency_wa_enabled;
#define XOR_CONFIG(chan) (0x10 + (chan * 4))
#define XOR_ACTIVATION(chan) (0x20 + (chan * 4))
#define WINDOW_BAR_ENABLE(chan) (0x240 + ((chan) << 2))
#define WINDOW_BASE(w) (0x250 + ((w) << 2))
#define WINDOW_SIZE(w) (0x270 + ((w) << 2))
#define WINDOW_REMAP_HIGH(w) (0x290 + ((w) << 2))
#define WINDOW_OVERRIDE_CTRL(chan) (0x2A0 + ((chan) << 2))
#define XOR_DEST_POINTER(chan) (0x2B0 + (chan * 4))
#define XOR_BLOCK_SIZE(chan) (0x2C0 + (chan * 4))
#define XOR_INIT_VALUE_LOW 0x2E0
#define XOR_INIT_VALUE_HIGH 0x2E4
static inline void mvebu_hwcc_armada375_sync_io_barrier_wa(void)
{
int idx = smp_processor_id();
/* Write '1' to the first word of the buffer */
writel(0x1, coherency_wa_buf[idx]);
/* Wait until the engine is idle */
while ((readl(xor_base + XOR_ACTIVATION(idx)) >> 4) & 0x3)
;
dmb();
/* Trigger channel */
writel(0x1, xor_base + XOR_ACTIVATION(idx));
/* Poll the data until it is cleared by the XOR transaction */
while (readl(coherency_wa_buf[idx]))
;
}
static void __init armada_375_coherency_init_wa(void)
{
const struct mbus_dram_target_info *dram;
struct device_node *xor_node;
struct property *xor_status;
struct clk *xor_clk;
u32 win_enable = 0;
int i;
pr_warn("enabling coherency workaround for Armada 375 Z1, one XOR engine disabled\n");
/*
* Since the workaround uses one XOR engine, we grab a
* reference to its Device Tree node first.
*/
xor_node = of_find_compatible_node(NULL, NULL, "marvell,orion-xor");
BUG_ON(!xor_node);
/*
* Then we mark it as disabled so that the real XOR driver
* will not use it.
*/
xor_status = kzalloc(sizeof(struct property), GFP_KERNEL);
BUG_ON(!xor_status);
xor_status->value = kstrdup("disabled", GFP_KERNEL);
BUG_ON(!xor_status->value);
xor_status->length = 8;
xor_status->name = kstrdup("status", GFP_KERNEL);
BUG_ON(!xor_status->name);
of_update_property(xor_node, xor_status);
/*
* And we remap the registers, get the clock, and do the
* initial configuration of the XOR engine.
*/
xor_base = of_iomap(xor_node, 0);
xor_high_base = of_iomap(xor_node, 1);
xor_clk = of_clk_get_by_name(xor_node, NULL);
BUG_ON(!xor_clk);
clk_prepare_enable(xor_clk);
dram = mv_mbus_dram_info();
for (i = 0; i < 8; i++) {
writel(0, xor_base + WINDOW_BASE(i));
writel(0, xor_base + WINDOW_SIZE(i));
if (i < 4)
writel(0, xor_base + WINDOW_REMAP_HIGH(i));
}
for (i = 0; i < dram->num_cs; i++) {
const struct mbus_dram_window *cs = dram->cs + i;
writel((cs->base & 0xffff0000) |
(cs->mbus_attr << 8) |
dram->mbus_dram_target_id, xor_base + WINDOW_BASE(i));
writel((cs->size - 1) & 0xffff0000, xor_base + WINDOW_SIZE(i));
win_enable |= (1 << i);
win_enable |= 3 << (16 + (2 * i));
}
writel(win_enable, xor_base + WINDOW_BAR_ENABLE(0));
writel(win_enable, xor_base + WINDOW_BAR_ENABLE(1));
writel(0, xor_base + WINDOW_OVERRIDE_CTRL(0));
writel(0, xor_base + WINDOW_OVERRIDE_CTRL(1));
for (i = 0; i < CONFIG_NR_CPUS; i++) {
coherency_wa_buf[i] = kzalloc(PAGE_SIZE, GFP_KERNEL);
BUG_ON(!coherency_wa_buf[i]);
/*
* We can't use the DMA mapping API, since we don't
* have a valid 'struct device' pointer
*/
coherency_wa_buf_phys[i] =
virt_to_phys(coherency_wa_buf[i]);
BUG_ON(!coherency_wa_buf_phys[i]);
/*
* Configure the XOR engine for memset operation, with
* a 128 bytes block size
*/
writel(0x444, xor_base + XOR_CONFIG(i));
writel(128, xor_base + XOR_BLOCK_SIZE(i));
writel(coherency_wa_buf_phys[i],
xor_base + XOR_DEST_POINTER(i));
}
writel(0x0, xor_base + XOR_INIT_VALUE_LOW);
writel(0x0, xor_base + XOR_INIT_VALUE_HIGH);
coherency_wa_enabled = true;
}
static inline void mvebu_hwcc_sync_io_barrier(void)
{
if (coherency_wa_enabled) {
mvebu_hwcc_armada375_sync_io_barrier_wa();
return;
}
writel(0x1, coherency_cpu_base + IO_SYNC_BARRIER_CTL_OFFSET);
while (readl(coherency_cpu_base + IO_SYNC_BARRIER_CTL_OFFSET) & 0x1);
}
@ -198,9 +352,17 @@ int __init coherency_init(void)
static int __init coherency_late_init(void)
{
if (coherency_available())
bus_register_notifier(&platform_bus_type,
&mvebu_hwcc_platform_nb);
int type = coherency_type();
if (type == COHERENCY_FABRIC_TYPE_NONE)
return 0;
if (type == COHERENCY_FABRIC_TYPE_ARMADA_375)
armada_375_coherency_init_wa();
bus_register_notifier(&platform_bus_type,
&mvebu_hwcc_platform_nb);
return 0;
}