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SubjectRe: [PATCHv4 2/2] iommu/arm-smmu: Get clock config from device tree
Hi Thor,

On Fri, Oct 05, 2018 at 03:57:00PM -0500, thor.thayer@linux.intel.com wrote:
> From: Thor Thayer <thor.thayer@linux.intel.com>
>
> Currently the clocks are specified in a structure as well as
> in the device tree. Since all the information about clocks can be
> pulled from the device tree, parse the device tree for the clock
> information if specified.
>
> This patch is dependent upon the following patch series that
> adds clocks to the driver.
> "[v16,0/5] iommu/arm-smmu: Add runtime pm/sleep support"
> https://patchwork.kernel.org/cover/10581891/
>
> particularly this patch which adds the clocks:
> "[v16,1/5] iommu/arm-smmu: Add pm_runtime/sleep ops"
> https://patchwork.kernel.org/patch/10581899/
>
> Request testing on different platforms for verification.
> This patch was tested on a Stratix10 SOCFPGA.
>
> Signed-off-by: Thor Thayer <thor.thayer@linux.intel.com>
> ---
> v4 Change dependency on pending patch series that adds clocks.
> Add code for parsing device tree for the clocks.
> v3 Change dependency on device tree bulk clock patches.
> v2 Add structure for SOCFPGA and add dependency on clock patch.
> ---
> drivers/iommu/arm-smmu.c | 30 +++++++++++++++++++++++++++---
> 1 file changed, 27 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
> index d315ca637097..3dd10663b09c 100644
> --- a/drivers/iommu/arm-smmu.c
> +++ b/drivers/iommu/arm-smmu.c
> @@ -44,6 +44,7 @@
> #include <linux/module.h>
> #include <linux/of.h>
> #include <linux/of_address.h>
> +#include <linux/of_clk.h>
> #include <linux/of_device.h>
> #include <linux/of_iommu.h>
> #include <linux/pci.h>
> @@ -2139,6 +2140,7 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
> const struct arm_smmu_match_data *data;
> struct device *dev = &pdev->dev;
> bool legacy_binding;
> + const char **parent_names;
>
> if (of_property_read_u32(dev->of_node, "#global-interrupts",
> &smmu->num_global_irqs)) {
> @@ -2149,9 +2151,25 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
> data = of_device_get_match_data(dev);
> smmu->version = data->version;
> smmu->model = data->model;
> - smmu->num_clks = data->num_clks;
> -
> - arm_smmu_fill_clk_data(smmu, data->clks);
> + smmu->num_clks = of_clk_get_parent_count(dev->of_node);
> + /* check to see if clocks were specified in DT */
> + if (smmu->num_clks) {
> + unsigned int i;
> +
> + parent_names = kmalloc_array(smmu->num_clks,
> + sizeof(*parent_names),
> + GFP_KERNEL);
> + if (!parent_names)
> + goto fail_clk_name;
> +
> + for (i = 0; i < smmu->num_clks; i++) {
> + if (of_property_read_string_index(dev->of_node,
> + "clock-names", i,
> + &parent_names[i]))
> + goto fail_clk_name;
> + }
> + arm_smmu_fill_clk_data(smmu, parent_names);
> + }
>
> parse_driver_options(smmu);
>
> @@ -2171,6 +2189,12 @@ static int arm_smmu_device_dt_probe(struct platform_device *pdev,
> smmu->features |= ARM_SMMU_FEAT_COHERENT_WALK;
>
> return 0;
> +
> +fail_clk_name:
> + kfree(parent_names);
> + /* clock-names required for clocks in devm_clk_bulk_get() */
> + dev_err(dev, "Error: clock-name required in device tree\n");

I think you can drop the "Error: " prefix here, but the rest of the patch
looks sensible to me. We just need to work out how this co-exists with
Vivek's approach of using match_data (see the other thread).

Will

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