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    Subject[PATCH 2/3] of/pci: Add of_pci_get_pcie_reset_suspend() to parse pcie-reset-suspend
    Date
    This helper can be used by drivers to determine the expected PERST#
    behavior when in low-power system suspend (e.g., S3). I've found the
    expected behavior to vary across a few different endpoint
    implementations.

    Signed-off-by: Brian Norris <briannorris@chromium.org>
    ---
    drivers/of/of_pci.c | 25 +++++++++++++++++++++++++
    include/linux/of_pci.h | 7 +++++++
    2 files changed, 32 insertions(+)

    diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
    index e9ec931f5b9a..ab2586f86094 100644
    --- a/drivers/of/of_pci.c
    +++ b/drivers/of/of_pci.c
    @@ -137,6 +137,31 @@ int of_pci_get_max_link_speed(struct device_node *node)
    }
    EXPORT_SYMBOL_GPL(of_pci_get_max_link_speed);

    +/**
    + * This function returns true if the PCIe controller should assert PCIe Reset
    + * (PERST#) when entering system suspend (e.g., S3).
    + *
    + * @node: device tree node with the reset property
    + *
    + * Returns 1 (meaning "assert reset") or 0 ("don't assert reset"), if the DT
    + * defined a valid behavior. Otherwise, returns a negative error code.
    + */
    +int of_pci_get_pcie_reset_suspend(struct device_node *node)
    +{
    + int ret;
    + u32 val;
    +
    + ret = of_property_read_u32(node, "pcie-reset-suspend", &val);
    + if (ret)
    + return ret;
    +
    + if (val > 1)
    + return -EINVAL;
    +
    + return val;
    +}
    +EXPORT_SYMBOL_GPL(of_pci_get_pcie_reset_suspend);
    +
    /**
    * of_pci_check_probe_only - Setup probe only mode if linux,pci-probe-only
    * is present and valid
    diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
    index 518c8d20647a..df453893080b 100644
    --- a/include/linux/of_pci.h
    +++ b/include/linux/of_pci.h
    @@ -17,6 +17,7 @@ int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
    int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
    int of_get_pci_domain_nr(struct device_node *node);
    int of_pci_get_max_link_speed(struct device_node *node);
    +int of_pci_get_pcie_reset_suspend(struct device_node *node);
    void of_pci_check_probe_only(void);
    int of_pci_map_rid(struct device_node *np, u32 rid,
    const char *map_name, const char *map_mask_name,
    @@ -69,6 +70,12 @@ of_pci_get_max_link_speed(struct device_node *node)
    return -EINVAL;
    }

    +static inline int
    +of_pci_get_pcie_reset_suspend(struct device_node *node)
    +{
    + return -EINVAL;
    +}
    +
    static inline void of_pci_check_probe_only(void) { }
    #endif

    --
    2.15.0.rc0.271.g36b669edcc-goog
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