From 1a4e90f25b2ceca3152efa6f7a9e0565c52e34c1 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Tue, 20 Feb 2018 20:25:04 +0000 Subject: iommu/rockchip: Perform a reset on shutdown Trying to do a kexec whilst the iommus are still on is proving to be a challenging exercise. It is terribly unsafe, as we're reusing the memory allocated for the page tables, leading to a likely crash. Let's implement a shutdown method that will at least try to stop DMA from going crazy behind our back. Note that we need to be extra cautious when doing so, as the IOMMU may not be clocked if controlled by a another master, as typical on Rockchip system. Suggested-by: Robin Murphy Signed-off-by: Marc Zyngier Reviewed-by: Robin Murphy Signed-off-by: Joerg Roedel --- drivers/iommu/rockchip-iommu.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'drivers') diff --git a/drivers/iommu/rockchip-iommu.c b/drivers/iommu/rockchip-iommu.c index 9d991c2d8767..6a3719e118da 100644 --- a/drivers/iommu/rockchip-iommu.c +++ b/drivers/iommu/rockchip-iommu.c @@ -1209,6 +1209,23 @@ static int rk_iommu_remove(struct platform_device *pdev) return 0; } +static void rk_iommu_shutdown(struct platform_device *pdev) +{ + struct rk_iommu *iommu = platform_get_drvdata(pdev); + + /* + * Be careful not to try to shutdown an otherwise unused + * IOMMU, as it is likely not to be clocked, and accessing it + * would just block. An IOMMU without a domain is likely to be + * unused, so let's use this as a (weak) guard. + */ + if (iommu && iommu->domain) { + rk_iommu_enable_stall(iommu); + rk_iommu_disable_paging(iommu); + rk_iommu_force_reset(iommu); + } +} + static const struct of_device_id rk_iommu_dt_ids[] = { { .compatible = "rockchip,iommu" }, { /* sentinel */ } @@ -1218,6 +1235,7 @@ MODULE_DEVICE_TABLE(of, rk_iommu_dt_ids); static struct platform_driver rk_iommu_driver = { .probe = rk_iommu_probe, .remove = rk_iommu_remove, + .shutdown = rk_iommu_shutdown, .driver = { .name = "rk_iommu", .of_match_table = rk_iommu_dt_ids, -- cgit v1.2.3