The remoteproc MMUs in OMAP4+ SoCs have some additional debug registers that can give out the PC value in addition to the MMU fault address. The PC value can be extracted properly only on the DSP cores, and is not available on the ARM processors within the IPU sub-systems. Instead, the MMUs have been enhanced to throw a bus-error response back to the IPU processors.
This functionality is programmable through the MMU_GP_REG register. The cores are simply stalled if the MMU_GP_REG.BUS_ERR_BACK_EN bit is not set. When set, a bus-error exception is raised allowing the processor to handle it as a bus fault and provide additional debug information. This feature is turned on by default by the driver on iommus supporting it. Signed-off-by: Subramaniam Chanderashekarapuram <subramaniam...@ti.com> Signed-off-by: Suman Anna <s-a...@ti.com> --- drivers/iommu/omap-iommu.c | 2 ++ drivers/iommu/omap-iommu.h | 5 +++++ drivers/iommu/omap-iommu2.c | 3 +++ 3 files changed, 10 insertions(+) diff --git a/drivers/iommu/omap-iommu.c b/drivers/iommu/omap-iommu.c index 4329ab1..e64025a 100644 --- a/drivers/iommu/omap-iommu.c +++ b/drivers/iommu/omap-iommu.c @@ -964,6 +964,8 @@ static int omap_iommu_probe(struct platform_device *pdev) if (err != 0) return err; obj->da_end = obj->da_start + len; + if (of_find_property(of, "ti,iommu-bus-err-back", NULL)) + obj->has_bus_err_back = MMU_GP_REG_BUS_ERR_BACK_EN; } else { obj->nr_tlb_entries = pdata->nr_tlb_entries; obj->name = pdata->name; diff --git a/drivers/iommu/omap-iommu.h b/drivers/iommu/omap-iommu.h index 1200842..ea920c3 100644 --- a/drivers/iommu/omap-iommu.h +++ b/drivers/iommu/omap-iommu.h @@ -52,6 +52,8 @@ struct omap_iommu { void *ctx; /* iommu context: registres saved area */ u32 da_start; u32 da_end; + + int has_bus_err_back; }; struct cr_regs { @@ -130,6 +132,7 @@ static inline struct omap_iommu *dev_to_omap_iommu(struct device *dev) #define MMU_READ_CAM 0x68 #define MMU_READ_RAM 0x6c #define MMU_EMU_FAULT_AD 0x70 +#define MMU_GP_REG 0x88 #define MMU_REG_SIZE 256 @@ -163,6 +166,8 @@ static inline struct omap_iommu *dev_to_omap_iommu(struct device *dev) #define MMU_RAM_MIXED_MASK (1 << MMU_RAM_MIXED_SHIFT) #define MMU_RAM_MIXED MMU_RAM_MIXED_MASK +#define MMU_GP_REG_BUS_ERR_BACK_EN 0x1 + /* * utilities for super page(16MB, 1MB, 64KB and 4KB) */ diff --git a/drivers/iommu/omap-iommu2.c b/drivers/iommu/omap-iommu2.c index d745094..5e1ea3b 100644 --- a/drivers/iommu/omap-iommu2.c +++ b/drivers/iommu/omap-iommu2.c @@ -98,6 +98,9 @@ static int omap2_iommu_enable(struct omap_iommu *obj) iommu_write_reg(obj, pa, MMU_TTB); + if (obj->has_bus_err_back) + iommu_write_reg(obj, MMU_GP_REG_BUS_ERR_BACK_EN, MMU_GP_REG); + __iommu_set_twl(obj, true); return 0; -- 1.8.5.3 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html