[PATCH 07/10] ARM: mvebu: implement Armada 375 coherency workaround
Thomas Petazzoni
thomas.petazzoni at free-electrons.com
Thu Mar 6 11:46:32 EST 2014
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. Note also that
the mvebu-mbus driver must be initialized prior to the coherency unit,
because the DRAM windows of the XOR engine must be configured during
the coherency unit initialization, due to this workaround.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
---
arch/arm/mach-mvebu/board-v7.c | 2 +-
arch/arm/mach-mvebu/coherency.c | 150 ++++++++++++++++++++++++++++++++++++++++
2 files changed, 151 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mach-mvebu/board-v7.c b/arch/arm/mach-mvebu/board-v7.c
index 256e6f6..6260cb8 100644
--- a/arch/arm/mach-mvebu/board-v7.c
+++ b/arch/arm/mach-mvebu/board-v7.c
@@ -80,8 +80,8 @@ static void __init mvebu_timer_and_clk_init(void)
of_clk_init(NULL);
clocksource_of_init();
mvebu_scu_enable();
- coherency_init();
BUG_ON(mvebu_mbus_dt_init(coherency_available()));
+ coherency_init();
#ifdef CONFIG_CACHE_L2X0
l2x0_of_init(0, ~0UL);
#endif
diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
index f63c868..73d56f2 100644
--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -24,6 +24,9 @@
#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 +69,154 @@ 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;
+
+ /*
+ * 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);
}
@@ -150,6 +299,7 @@ static void __init armada_370_coherency_init(struct device_node *np)
static void __init armada_375_coherency_init(struct device_node *np)
{
coherency_cpu_base = of_iomap(np, 0);
+ armada_375_coherency_init_wa();
}
static int coherency_type(void)
--
1.8.3.2
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