From 5ab5afd8ba837560f76f8ee527271d2e819bcaef Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Mon, 14 Apr 2014 15:47:05 +0200 Subject: [PATCH] ARM: mvebu: implement Armada 375 coherency workaround 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 Link: https://lkml.kernel.org/r/1397483228-25625-8-git-send-email-thomas.petazzoni@free-electrons.com Signed-off-by: Jason Cooper --- arch/arm/mach-mvebu/coherency.c | 168 +++++++++++++++++++++++++++++++- 1 file changed, 165 insertions(+), 3 deletions(-) diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c index 7ccaf87fd772..75db33ef93ee 100644 --- a/arch/arm/mach-mvebu/coherency.c +++ b/arch/arm/mach-mvebu/coherency.c @@ -17,6 +17,8 @@ * supplies basic routines for configuring and controlling hardware coherency */ +#define pr_fmt(fmt) "mvebu-coherency: " fmt + #include #include #include @@ -24,6 +26,9 @@ #include #include #include +#include +#include +#include #include #include #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; } -- 2.39.2