[RFC 10/10] mmc: sdhci-tegra: Add IOMMU support
From: Hiroshi DOyu <hidden>
Date: 2014-06-27 09:46:10
Also in:
linux-devicetree, linux-iommu, linux-tegra, lkml
Thierry Reding [off-list ref] writes:
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From: Thierry Reding <redacted> Attach to the device's master interface of the IOMMU at .probe() time. IOMMU support becomes available via the DMA mapping API interoperation code, but this explicit attachment is necessary to ensure proper probe order. Signed-off-by: Thierry Reding <redacted> --- drivers/mmc/host/sdhci-tegra.c | 8 ++++++++ 1 file changed, 8 insertions(+)diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c index 33100d10d176..b884614fa4e6 100644 --- a/drivers/mmc/host/sdhci-tegra.c +++ b/drivers/mmc/host/sdhci-tegra.c@@ -15,6 +15,7 @@ #include <linux/err.h> #include <linux/module.h> #include <linux/init.h> +#include <linux/iommu.h> #include <linux/platform_device.h> #include <linux/clk.h> #include <linux/io.h>@@ -237,6 +238,11 @@ static int sdhci_tegra_probe(struct platform_device *pdev) match = of_match_device(sdhci_tegra_dt_match, &pdev->dev); if (!match) return -EINVAL; + + rc = iommu_attach(&pdev->dev); + if (rc < 0) + return rc; +
I thought that, if we consider that ->probe() should include minimal H/W probing so that DMA API call in ->probe() could be deferred after ->probe() and till it's in use actually, like opening a device node. For me this decision(minimal h/w probe) seemed logical but it would add a new restriction. One advantage is that we could still keep all drivers wihtout any IOMMU code if it doesn't call DMA API in ->probe().
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soc_data = match->data; host = sdhci_pltfm_init(pdev, soc_data->pdata, 0);@@ -310,6 +316,8 @@ static int sdhci_tegra_remove(struct platform_device *pdev) clk_disable_unprepare(pltfm_host->clk); clk_put(pltfm_host->clk); + iommu_detach(&pdev->dev); + sdhci_pltfm_free(pdev); return 0;