diff options
Diffstat (limited to 'arch/arm/mach-omap2/omap4-common.c')
| -rw-r--r-- | arch/arm/mach-omap2/omap4-common.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/arch/arm/mach-omap2/omap4-common.c b/arch/arm/mach-omap2/omap4-common.c index 16350eefa66c..949696b6f17b 100644 --- a/arch/arm/mach-omap2/omap4-common.c +++ b/arch/arm/mach-omap2/omap4-common.c @@ -51,6 +51,127 @@ static void __iomem *twd_base; #define IRQ_LOCALTIMER 29 +#ifdef CONFIG_OMAP_INTERCONNECT_BARRIER + +/* Used to implement memory barrier on DRAM path */ +#define OMAP4_DRAM_BARRIER_VA 0xfe600000 + +static void __iomem *dram_sync, *sram_sync; +static phys_addr_t dram_sync_paddr; +static u32 dram_sync_size; + +/* + * The OMAP4 bus structure contains asynchrnous bridges which can buffer + * data writes from the MPU. These asynchronous bridges can be found on + * paths between the MPU to EMIF, and the MPU to L3 interconnects. + * + * We need to be careful about re-ordering which can happen as a result + * of different accesses being performed via different paths, and + * therefore different asynchronous bridges. + */ + +/* + * OMAP4 interconnect barrier which is called for each mb() and wmb(). + * This is to ensure that normal paths to DRAM (normal memory, cacheable + * accesses) are properly synchronised with writes to DMA coherent memory + * (normal memory, uncacheable) and device writes. + * + * The mb() and wmb() barriers only operate only on the MPU->MA->EMIF + * path, as we need to ensure that data is visible to other system + * masters prior to writes to those system masters being seen. + * + * Note: the SRAM path is not synchronised via mb() and wmb(). + */ +static void omap4_mb(void) +{ + if (dram_sync) + writel_relaxed(0, dram_sync); +} + +/* + * OMAP4 Errata i688 - asynchronous bridge corruption when entering WFI. + * + * If a data is stalled inside asynchronous bridge because of back + * pressure, it may be accepted multiple times, creating pointer + * misalignment that will corrupt next transfers on that data path until + * next reset of the system. No recovery procedure once the issue is hit, + * the path remains consistently broken. + * + * Async bridges can be found on paths between MPU to EMIF and MPU to L3 + * interconnects. + * + * This situation can happen only when the idle is initiated by a Master + * Request Disconnection (which is trigged by software when executing WFI + * on the CPU). + * + * The work-around for this errata needs all the initiators connected + * through an async bridge to ensure that data path is properly drained + * before issuing WFI. This condition will be met if one Strongly ordered + * access is performed to the target right before executing the WFI. + * + * In MPU case, L3 T2ASYNC FIFO and DDR T2ASYNC FIFO needs to be drained. + * IO barrier ensure that there is no synchronisation loss on initiators + * operating on both interconnect port simultaneously. + * + * This is a stronger version of the OMAP4 memory barrier below, and + * operates on both the MPU->MA->EMIF path but also the MPU->OCP path + * as well, and is necessary prior to executing a WFI. + */ +void omap_interconnect_sync(void) +{ + if (dram_sync && sram_sync) { + writel_relaxed(readl_relaxed(dram_sync), dram_sync); + writel_relaxed(readl_relaxed(sram_sync), sram_sync); + isb(); + } +} + +static int __init omap4_sram_init(void) +{ + struct device_node *np; + struct gen_pool *sram_pool; + + np = of_find_compatible_node(NULL, NULL, "ti,omap4-mpu"); + if (!np) + pr_warn("%s:Unable to allocate sram needed to handle errata I688\n", + __func__); + sram_pool = of_gen_pool_get(np, "sram", 0); + if (!sram_pool) + pr_warn("%s:Unable to get sram pool needed to handle errata I688\n", + __func__); + else + sram_sync = (void *)gen_pool_alloc(sram_pool, PAGE_SIZE); + + return 0; +} +omap_arch_initcall(omap4_sram_init); + +/* Steal one page physical memory for barrier implementation */ +void __init omap_barrier_reserve_memblock(void) +{ + dram_sync_size = ALIGN(PAGE_SIZE, SZ_1M); + dram_sync_paddr = arm_memblock_steal(dram_sync_size, SZ_1M); +} + +void __init omap_barriers_init(void) +{ + struct map_desc dram_io_desc[1]; + + dram_io_desc[0].virtual = OMAP4_DRAM_BARRIER_VA; + dram_io_desc[0].pfn = __phys_to_pfn(dram_sync_paddr); + dram_io_desc[0].length = dram_sync_size; + dram_io_desc[0].type = MT_MEMORY_RW_SO; + iotable_init(dram_io_desc, ARRAY_SIZE(dram_io_desc)); + dram_sync = (void __iomem *) dram_io_desc[0].virtual; + + pr_info("OMAP4: Map %pa to %p for dram barrier\n", + &dram_sync_paddr, dram_sync); + + soc_mb = omap4_mb; +} + +#endif + void gic_dist_disable(void) { if (gic_dist_base_addr) |