Re: [Qemu-ppc] [PATCH v4 2/2] spapr: generate DT node names

[Laurent Vivier]

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On 29/09/2015 07:18, David Gibson wrote:
> On Thu, Sep 24, 2015 at 12:27:39PM +0200, Laurent Vivier wrote:
>> When DT node names for PCI devices are generated by SLOF, they
>> are generated according to the type of the device (for instance,
>> ethernet for virtio-net-pci device).
>> 
>> Node name for hotplugged devices is generated by QEMU. This patch
>> adds the mechanic to QEMU to create the node name according to
>> the device type too.
>> 
>> The data structure has been roughly copied from
>> OpenBIOS/OpenHackware, node names from SLOF.
>> 
>> Example:
>> 
>> Hotplugging some PCI cards with QEMU monitor:
>> 
>> device_add virtio-tablet-pci device_add virtio-serial-pci 
>> device_add virtio-mouse-pci device_add virtio-scsi-pci device_add
>> virtio-gpu-pci device_add ne2k_pci device_add nec-usb-xhci 
>> device_add intel-hda
>> 
>> What we can see in linux device tree:
>> 
>> for dir in /proc/device-tree/address@hidden/address@hidden/; do echo
>> $dir cat $dir/name echo done
>> 
>> WITHOUT this patch:
>> 
>> /proc/device-tree/address@hidden/address@hidden/ pci 
>> /proc/device-tree/address@hidden/address@hidden/ pci 
>> /proc/device-tree/address@hidden/address@hidden/ pci 
>> /proc/device-tree/address@hidden/address@hidden/ pci 
>> /proc/device-tree/address@hidden/address@hidden/ pci 
>> /proc/device-tree/address@hidden/address@hidden/ pci 
>> /proc/device-tree/address@hidden/address@hidden/ pci 
>> /proc/device-tree/address@hidden/address@hidden/ pci
>> 
>> WITH this patch:
>> 
>> /proc/device-tree/address@hidden/address@hidden/
>>
>> 
communication-controller
>> /proc/device-tree/address@hidden/address@hidden/ display 
>> /proc/device-tree/address@hidden/address@hidden/ ethernet 
>> /proc/device-tree/address@hidden/address@hidden/ 
>> input-controller /proc/device-tree/address@hidden/address@hidden/ 
>> mouse /proc/device-tree/address@hidden/address@hidden/ 
>> multimedia-device /proc/device-tree/address@hidden/address@hidden/ 
>> scsi /proc/device-tree/address@hidden/address@hidden/ usb-xhci
>> 
>> Signed-off-by: Laurent Vivier <address@hidden> Reviewed-by:
>> Thomas Huth <address@hidden>
> 
> Concept and approach seem good to me.
> 
> 
>> --- hw/ppc/spapr_pci.c | 292
>> ++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file
>> changed, 278 insertions(+), 14 deletions(-)
>> 
>> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c index
>> a2feb4c..63eb28c 100644 --- a/hw/ppc/spapr_pci.c +++
>> b/hw/ppc/spapr_pci.c @@ -38,6 +38,7 @@
>> 
>> #include "hw/pci/pci_bridge.h" #include "hw/pci/pci_bus.h" 
>> +#include "hw/pci/pci_ids.h" #include "hw/ppc/spapr_drc.h" 
>> #include "sysemu/device_tree.h"
>> 
>> @@ -944,6 +945,276 @@ static void
>> populate_resource_props(PCIDevice *d, ResourceProps *rp) 
>> rp->assigned_len = assigned_idx * sizeof(ResourceFields); }
>> 
>> +typedef struct PCIClass PCIClass; +typedef struct PCISubClass
>> PCISubClass; +typedef struct PCIIFace PCIIFace; + +struct
>> PCIIFace { +    uint8_t iface; +    const char *name; +}; + 
>> +struct PCISubClass { +    uint8_t subclass; +    const char
>> *name; +    const PCIIFace *iface; +}; +#define SUBCLASS(a)
>> ((uint8_t)a) +#define IFACE(a)    ((uint8_t)a) + +struct PCIClass
>> { +    const char *name; +    const PCISubClass *subc; +}; + 
>> +static const PCISubClass undef_subclass[] = { +    {
>> IFACE(PCI_CLASS_NOT_DEFINED_VGA), "display", NULL },
> 
> These IFACE and SUBCLASS macro calls seem ugly to me.  What's the 
> purpose of them?

In fact, in case of subclass, the value is ((CLASS << 8) + SUBCLASS)
and in case of iface is ((CLASS << 16) + (SUBCLASS << 8) + IFACE).
To build the array we need either only the CLASS or the ICLASS of the
value. These macros (which are indentical) take the low order byte to
have only the subclass or the iface to put it in the array.

And on this line, it's wrong, we should use SUBCLASS():

#define PCI_CLASS_NOT_DEFINED            0x0000

So class is "0x00"

#define PCI_CLASS_NOT_DEFINED_VGA        0x0001

subclass is "0x01".

For the case of iface:

#define PCI_BASE_CLASS_SERIAL            0x0c

class is "serial", 0x0c

#define PCI_CLASS_SERIAL_USB             0x0c03

subclass is "usb", 0x03

#define PCI_CLASS_SERIAL_USB_XHCI        0x0c0330

iface is "xhci", 0x30

So of course I can remove macros SUBCLASS() and IFACE() and simply
replace them by a cast "(uint8_t *)".

> 
> [snip]
>> +static const char *pci_find_device_name(uint8_t class, uint8_t
>> subclass, +                                        uint8_t
>> iface) +{ +    const PCIClass *pclass; +    const PCISubClass
>> *psubclass; +    const PCIIFace *piface; +    const char *name; 
>> + +    if (class >= ARRAY_SIZE(pci_classes)) { +        return
>> "pci"; +    } + +    pclass = pci_classes + class; +    name =
>> pclass->name; + +    if (pclass->subc == NULL) { +        return
>> name; +    } + +    psubclass = pclass->subc; +    while
>> (psubclass->subclass != 0xff) { +        if (psubclass->subclass
>> == subclass) { +            name = psubclass->name; +
>> break; +        } +        psubclass++; +    } + +    piface =
>> psubclass->iface; +    if (piface == NULL) { +        return
>> name; +    } +    while (piface->iface != 0xff) { +        if
>> (piface->iface == iface) { +            name = piface->name; +
>> break; +        } +        piface++; +    } + +    return name; 
>> +} + +static void pci_get_node_name(char *nodename, int len,
>> PCIDevice *dev) +{ +    int slot = PCI_SLOT(dev->devfn); +    int
>> func = PCI_FUNC(dev->devfn); +    uint32_t ccode =
>> pci_default_read_config(dev, PCI_CLASS_PROG, 3); +    const char
>> *name; + +    name = pci_find_device_name((ccode >> 16) & 0xff,
>> (ccode >> 8) & 0xff, +                                ccode &
>> 0xff); + +    if (func != 0) { +        snprintf(nodename, len,
>> "address@hidden,%x", name, slot, func); +    } else { +
>> snprintf(nodename, len, "address@hidden", name, slot); +    } +} + static
>> uint32_t spapr_phb_get_pci_drc_index(sPAPRPHBState *phb, 
>> PCIDevice *pdev);
>> 
>> @@ -955,6 +1226,7 @@ static int
>> spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int
>> offset, int pci_status, err; char *buf = NULL; uint32_t drc_index
>> = spapr_phb_get_pci_drc_index(sphb, dev); +    uint32_t ccode =
>> pci_default_read_config(dev, PCI_CLASS_PROG, 3);
>> 
>> if (pci_default_read_config(dev, PCI_HEADER_TYPE, 1) == 
>> PCI_HEADER_TYPE_BRIDGE) { @@ -968,8 +1240,7 @@ static int
>> spapr_populate_pci_child_dt(PCIDevice *dev, void *fdt, int
>> offset, pci_default_read_config(dev, PCI_DEVICE_ID, 2))); 
>> _FDT(fdt_setprop_cell(fdt, offset, "revision-id", 
>> pci_default_read_config(dev, PCI_REVISION_ID, 1))); -
>> _FDT(fdt_setprop_cell(fdt, offset, "class-code", -
>> pci_default_read_config(dev, PCI_CLASS_PROG, 3))); +
>> _FDT(fdt_setprop_cell(fdt, offset, "class-code", ccode)); if
>> (pci_default_read_config(dev, PCI_INTERRUPT_PIN, 1)) { 
>> _FDT(fdt_setprop_cell(fdt, offset, "interrupts", 
>> pci_default_read_config(dev, PCI_INTERRUPT_PIN, 1))); @@ -1010,11
>> +1281,10 @@ static int spapr_populate_pci_child_dt(PCIDevice
>> *dev, void *fdt, int offset, _FDT(fdt_setprop(fdt, offset,
>> "udf-supported", NULL, 0)); }
>> 
>> -    /* NOTE: this is normally generated by firmware via
>> path/unit name, -     * but in our case we must set it manually
>> since it does not get -     * processed by OF beforehand -
>> */ -    _FDT(fdt_setprop_string(fdt, offset, "name", "pci")); +
>> _FDT(fdt_setprop_string(fdt, offset, "name", +
>> pci_find_device_name((ccode >> 16) & 0xff, +
>> (ccode >> 8) & 0xff, +
>> ccode & 0xff)));
> 
> Heh.  This isn't wrong, but there's a non-obvious wrinkle as to
> why. Generally flattened trees shouldn't require the 'name'
> property (the consumer is supposed to infer that from the node
> name).  However, since this may also be used to generate tree
> fragments which get passed through the PAPR dynamic reconfiguration
> interface, and that *does* expect the name property to be passed
> through.

In fact, this is also the behavior of SLOF.

> 
>> buf = spapr_phb_get_loc_code(sphb, dev); if (!buf) { 
>> error_report("Failed setting the ibm,loc-code"); @@ -1051,15
>> +1321,9 @@ static int spapr_create_pci_child_dt(sPAPRPHBState
>> *phb, PCIDevice *dev, void *fdt, int node_offset) { int offset,
>> ret; -    int slot = PCI_SLOT(dev->devfn); -    int func =
>> PCI_FUNC(dev->devfn); char nodename[FDT_NAME_MAX];
>> 
>> -    if (func != 0) { -        snprintf(nodename, FDT_NAME_MAX,
>> "address@hidden,%x", slot, func); -    } else { -
>> snprintf(nodename, FDT_NAME_MAX, "address@hidden", slot); -    } +
>> pci_get_node_name(nodename, FDT_NAME_MAX, dev); offset =
>> fdt_add_subnode(fdt, node_offset, nodename); ret =
>> spapr_populate_pci_child_dt(dev, fdt, offset, phb);
>> 
> 
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