Re: [Qemu-devel] [RESEND RFC 5/6] hw/arm/sysbus-fdt: helpers for clock node generation

["Alex Bennée" <alex.bennee@linaro.org>]

Eric Auger <eric.auger@linaro.org> writes:

> Some passthrough'ed devices depend on clock nodes. Those need to be
> generated in the guest device tree. This patch introduces some helpers
> to build a clock node from information retrieved from host device tree.
>
> - inherit_properties copies properties from a host device tree node to
>   a guest device tree node
> - fdt_build_clock_node builds a guest clock node and checks the host
>   fellow clock is a fixed one.
>
> fdt_build_clock_node will become static as soon as a they get used
>
> Signed-off-by: Eric Auger <eric.auger@linaro.org>
> ---
>  hw/arm/sysbus-fdt.c | 110 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 110 insertions(+)
>
> diff --git a/hw/arm/sysbus-fdt.c b/hw/arm/sysbus-fdt.c
> index 9d28797..22e5801 100644
> --- a/hw/arm/sysbus-fdt.c
> +++ b/hw/arm/sysbus-fdt.c
> @@ -21,6 +21,7 @@
>   *
>   */
>
> +#include <libfdt.h>
>  #include "hw/arm/sysbus-fdt.h"
>  #include "qemu/error-report.h"
>  #include "sysemu/device_tree.h"
> @@ -56,6 +57,115 @@ typedef struct NodeCreationPair {
>      int (*add_fdt_node_fn)(SysBusDevice *sbdev, void *opaque);
>  } NodeCreationPair;
>
> +/* helpers */
> +
> +struct HostProperty {
> +    const char *name;
> +    bool optional;
> +};
> +
> +typedef struct HostProperty HostProperty;
> +
> +/**
> + * inherit_properties
> + *
> + * copies properties listed in an array from host device tree to
> + * guest device tree. If a non optional property is not found, the
> + * function exits. Not found optional ones are ignored.
> + * props: array of HostProperty to copy
> + * nb_props: number of properties in the array
> + * host_dt: host device tree blob
> + * guest_dt: guest device tree blob
> + * node_path: host dt node path where the property is supposed to be
> +              found
> + * nodename: guest node name the properties should be added to
> + *
> + */
> +static void inherit_properties(HostProperty *props, int nb_props,
> +                               void *host_fdt, void *guest_fdt,
> +                               char *node_path, char *nodename)
> +{
> +    int i, prop_len;
> +    const void *r;
> +
> +    for (i = 0; i < nb_props; i++) {
> +        r = qemu_fdt_getprop_optional(host_fdt, node_path,
> +                             props[i].name,
> +                             props[i].optional,
> +                             &prop_len);

indentation?

> +        if (r) {
> +            qemu_fdt_setprop(guest_fdt, nodename,
> +                             props[i].name, r, prop_len);
> +        }
> +    }
> +}
> +
> +/* clock properties whose values are copied/pasted from host */
> +static HostProperty clock_inherited_properties[] = {
> +    {"compatible", 0},
> +    {"#clock-cells", 0},
> +    {"clock-frequency", 1},
> +    {"clock-output-names", 1},
> +};
> +
> +/**
> + * fdt_build_clock_node
> + *
> + * Build a guest clock node, used as a dependency from a passthrough'ed
> + * device. Most information are retrieved from the host fellow node.
> + * Also check the host clock is a fixed one.
> + *
> + * host_fdt: host device tree blob from which info are retrieved
> + * guest_fdt: guest device tree blob where the clock node is added
> + * host_phandle: phandle of the clock in host device tree
> + * guest_phandle: phandle to assign to the guest node
> + */
> +int fdt_build_clock_node(void *host_fdt, void *guest_fdt,
> +                                uint32_t host_phandle,
> +                                uint32_t guest_phandle);
> +int fdt_build_clock_node(void *host_fdt, void *guest_fdt,
> +                                uint32_t host_phandle,
> +                                uint32_t guest_phandle)

I'm seeing double here ;-)

> +{
> +    char node_path[256];
> +    char *nodename;
> +    const void *r;
> +    int ret, prop_len;
> +
> +    ret = fdt_node_offset_by_phandle(host_fdt, host_phandle);
> +    if (ret <= 0) {
> +        error_report("not able to locate clock handle %d in host device tree\n",
> +                     host_phandle);
> +        goto out;
> +    }
> +    ret = fdt_get_path(host_fdt, ret, node_path, 256);
> +    if (ret < 0) {
> +        error_report("not able to retrieve node path for clock handle %d\n",
> +                     host_phandle);
> +        goto out;
> +    }
> +
> +    r = qemu_fdt_getprop(host_fdt, node_path, "compatible", &prop_len);
> +    if (strcmp(r, "fixed-clock")) {
> +        error_report("clock handle %d is not a fixed clock\n", host_phandle);
> +        ret = -1;
> +        goto out;
> +    }
> +
> +    nodename = strrchr(node_path, '/');
> +    qemu_fdt_add_subnode(guest_fdt, nodename);
> +
> +    inherit_properties(clock_inherited_properties,
> +                       ARRAY_SIZE(clock_inherited_properties),
> +                       host_fdt, guest_fdt,
> +                       node_path, nodename);
> +
> +    qemu_fdt_setprop_cell(guest_fdt, nodename, "phandle", guest_phandle);
> +
> +out:
> +    return ret;
> +}
> +
>  /* Device Specific Code */
>
>  /**


--
Alex Bennée