Re: [Qemu-devel] [PATCH v8 1/3] hw/arm/sysbus-fdt: helpers for platform bus nodes addition

[Eric Auger]

Hi Peter,
On 01/06/2015 07:40 PM, Peter Maydell wrote:
> On 5 January 2015 at 16:14, Eric Auger <address@hidden> wrote:
>> This new C module will be used by ARM machine files to generate
>> platform bus node and their dynamic sysbus device tree nodes.
>>
>> Dynamic sysbus device node addition is done in a machine init
>> done notifier. arm_register_platform_bus_fdt_creator does the
>> registration of this latter and is supposed to be called by
>> ARM machine files that support platform bus and their dynamic
>> sysbus. Addition of dynamic sysbus nodes is done only if the
>> user did not provide any dtb.
>>
>> Signed-off-by: Alexander Graf <address@hidden>
>> Signed-off-by: Eric Auger <address@hidden>
>> Reviewed-by: Shannon Zhao <address@hidden>
>> Reviewed-by: Alexander Graf <address@hidden>
>>
>> ---
>> v7 -> v8:
>> add Reviewed-by from Alex and Shannon
>>
>> v6 -> v7:
>> - revert indentation in add_fdt_node_functions
>>
>> v5 -> v6:
>> - add_all_platform_bus_fdt_nodes is not a modify_dtb function anymore
>> - it now takes a handle to an ARMPlatformBusFdtParams.
>> - fdt pointer is checked in case this notifier is executed after the
>>   one that executes the load_dtb (this latter deallocates the fdt pointer)
>> - check of fdt_filename moved in here.
>> - upgrade_dtb is removed
>> - copyright aligned between .h and .c
>>
>> v4 -> v5:
>> - change indentation in add_fdt_node_functions. Also becomes a
>>   static const.
>> - ARMPlatformBusFdtParams.system_params becomes a pointer to
>>   a const ARMPlatformBusSystemParams
>> - removes platform-bus.h second inclusion
>>
>> v3 -> v4:
>> - dyn_sysbus_devtree.c renamed into sysbus-fdt.c
>> - use new PlatformBusDevice object
>> - the dtb upgrade is done through modify_dtb. Before the fdt
>>   was recreated from scratch. When the user provided a dtb this
>>   latter was overwritten which was not correct.
>> - an array contains the association between device type names
>>   and their node creation function
>> - I must aknowledge I did not find any cleaner way to implement
>>   a FDT_BUILDER interface, as suggested by Paolo. The class method
>>   would need to be initialized somewhere and since it cannot
>>   happen in the device itself - according to Alex & Peter comments -,
>>   I don't see when I shall associate the device type and its
>>   interface implementation.
>>
>> v2 -> v3:
>> - add arm_ prefix
>> - arm_sysbus_device_create_devtree becomes static
>>
>> v1 -> v2:
>> - Code moved in an arch specific file to accomodate architecture
>>   dependent specificities.
>> - remove platform_bus_base from PlatformDevtreeData
>>
>> v1: code originally written by Alex Graf in e500.c and reused for
>> ARM [Eric Auger]
>> ---
>>  hw/arm/Makefile.objs        |   1 +
>>  hw/arm/sysbus-fdt.c         | 173 
>> ++++++++++++++++++++++++++++++++++++++++++++
>>  include/hw/arm/sysbus-fdt.h |  60 +++++++++++++++
>>  3 files changed, 234 insertions(+)
>>  create mode 100644 hw/arm/sysbus-fdt.c
>>  create mode 100644 include/hw/arm/sysbus-fdt.h
>>
>> diff --git a/hw/arm/Makefile.objs b/hw/arm/Makefile.objs
>> index 6088e53..0cc63e1 100644
>> --- a/hw/arm/Makefile.objs
>> +++ b/hw/arm/Makefile.objs
>> @@ -3,6 +3,7 @@ obj-$(CONFIG_DIGIC) += digic_boards.o
>>  obj-y += integratorcp.o kzm.o mainstone.o musicpal.o nseries.o
>>  obj-y += omap_sx1.o palm.o realview.o spitz.o stellaris.o
>>  obj-y += tosa.o versatilepb.o vexpress.o virt.o xilinx_zynq.o z2.o
>> +obj-y += sysbus-fdt.o
>>
>>  obj-y += armv7m.o exynos4210.o pxa2xx.o pxa2xx_gpio.o pxa2xx_pic.o
>>  obj-$(CONFIG_DIGIC) += digic.o
>> diff --git a/hw/arm/sysbus-fdt.c b/hw/arm/sysbus-fdt.c
>> new file mode 100644
>> index 0000000..a1dc0aa
>> --- /dev/null
>> +++ b/hw/arm/sysbus-fdt.c
>> @@ -0,0 +1,173 @@
>> +/*
>> + * ARM Platform Bus device tree generation helpers
>> + *
>> + * Copyright (c) 2014 Linaro Limited
>> + *
>> + * Authors:
>> + *  Alex Graf <address@hidden>
>> + *  Eric Auger <address@hidden>
>> + *
>> + * This program is free software; you can redistribute it and/or modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2 or later, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
>> + * more details.
>> + *
>> + * You should have received a copy of the GNU General Public License along 
>> with
>> + * this program.  If not, see <http://www.gnu.org/licenses/>.
>> + *
>> + */
>> +
>> +#include "hw/arm/sysbus-fdt.h"
>> +#include "qemu/error-report.h"
>> +#include "sysemu/device_tree.h"
>> +#include "hw/platform-bus.h"
>> +#include "sysemu/sysemu.h"
>> +
>> +/*
>> + * internal struct that contains the information to create dynamic
>> + * sysbus device node
>> + */
>> +typedef struct PlatformBusFdtData {
> 
> FDT is an acronym, so "PlatformBusFDTData" would be nicer.
> (Similar remarks apply for some other struct type names.)
Sure
> 
>> +    void *fdt; /* device tree handle */
>> +    int irq_start; /* index of the first IRQ usable by platform bus devices 
>> */
>> +    const char *pbus_node_name; /* name of the platform bus node */
>> +    PlatformBusDevice *pbus;
>> +} PlatformBusFdtData;
>> +
>> +/*
>> + * struct used when calling the machine init done notifier
>> + * that constructs the fdt nodes of platform bus devices
>> + */
>> +typedef struct PlatformBusFdtNotifierParams {
>> +    ARMPlatformBusFdtParams *fdt_params;
>> +    Notifier notifier;
> 
> Weird ordering again. If you put notifier first then you can do
> 
>    PlatformBusFdtNotifier *p = DO_UPCAST(PlatformBusFdtNotifier,
>                                          notifier, notifier);
> 
> rather than raw container_of calls. (This is of course assuming
> you see this as a type-of-notifier, which seems reasonable to
> me...hence the tweak to the struct name.)
Yes it is the case, I will correct the order.
> 
>> +} PlatformBusFdtNotifierParams;
>> +
>> +/* struct that associates a device type name and a node creation function */
>> +typedef struct NodeCreationPair {
>> +    const char *typename;
>> +    int (*add_fdt_node_fn)(SysBusDevice *sbdev, void *opaque);
>> +} NodeCreationPair;
>> +
>> +/* list of supported dynamic sysbus devices */
>> +static const NodeCreationPair add_fdt_node_functions[] = {
>> +    {"", NULL}, /*last element*/
> 
> Missing spaces: /* last element */
sure
> 
>> +};
>> +
>> +/**
>> + * add_fdt_node - add the device tree node of a dynamic sysbus device
>> + *
>> + * @sbdev: handle to the sysbus device
>> + * @opaque: handle to the PlatformBusFdtData
>> + *
>> + * Checks the sysbus type belongs to the list of device types that
>> + * are dynamically instantiable and in the positive call the node
> 
> s/and in the positive/and if so/
thanks
> 
>> + * creation function.
>> + */
>> +static int add_fdt_node(SysBusDevice *sbdev, void *opaque)
>> +{
>> +    int i;
>> +
>> +    for (i = 0; i < ARRAY_SIZE(add_fdt_node_functions); i++) {
>> +        if (!strcmp(object_get_typename(OBJECT(sbdev)),
>> +                    add_fdt_node_functions[i].typename)) {
>> +            add_fdt_node_functions[i].add_fdt_node_fn(sbdev, opaque);
>> +            return 0;
>> +        }
>> +    }
>> +    error_report("Device %s can not be dynamically instantiated",
>> +                     qdev_fw_name(DEVICE(sbdev)));
>> +    return 1;
>> +}
>> +
>> +/**
>> + * add_all_platform_bus_fdt_nodes - create all the platform bus nodes
>> + *
>> + * builds the parent platform bus node and all the nodes of dynamic
>> + * sysbus devices attached to it.
>> + */
>> +static void add_all_platform_bus_fdt_nodes(ARMPlatformBusFdtParams 
>> *fdt_params)
>> +{
>> +    const char platcomp[] = "qemu,platform\0simple-bus";
>> +    PlatformBusDevice *pbus;
>> +    DeviceState *dev;
>> +    gchar *node;
>> +    uint64_t addr, size;
>> +    int irq_start, dtb_size;
>> +    struct arm_boot_info *info = fdt_params->binfo;
>> +    const ARMPlatformBusSystemParams *params = fdt_params->system_params;
>> +    const char *intc = fdt_params->intc;
>> +    void *fdt = info->get_dtb(info, &dtb_size);
>> +
>> +    /*
>> +     * In case the user provided a dtb, we assume he already integrated the
> 
> s/In case/If/. s/he/they/.
OK
> 
>> +     * dynamic sysbus nodes. This corresponds to a use case where the 
>> dynamic
>> +     * sysbus nodes are complex and their generation is not yet supported. 
>> In
>> +     * case the use can take in charge the guest dt while qemu takes in 
>> charge
>> +     * the qom stuff.
> 
> "can take charge of".
thanks
> 
>> +     */
>> +    if (info->dtb_filename) {
>> +        return;
>> +    }
>> +
>> +    if (!fdt) {
>> +        fprintf(stderr,
>> +                "fdt NULL pointer: platform bus nodes cannot be added\n") ;
>> +        return;
>> +    }
> 
> When can this happen? If it can happen due to user command line error
> or similar, the error message should be more useful to the user.
> If it can only happen due to a bug in the board model (which I think
> is the case), then just assert(fdt);
Indeed this was meant to warn about a bug in board model. I will use
assert then.
> 
>> +
>> +    node = g_strdup_printf("/address@hidden"PRIx64, 
>> params->platform_bus_base);
>> +    addr = params->platform_bus_base;
>> +    size = params->platform_bus_size;
>> +    irq_start = params->platform_bus_first_irq;
>> +
>> +    /* Create a /platform node that we can put all devices into */
>> +    qemu_fdt_add_subnode(fdt, node);
>> +    qemu_fdt_setprop(fdt, node, "compatible", platcomp, sizeof(platcomp));
>> +
>> +    /* Our platform bus region is less than 32bit big, so 1 cell is enough 
>> for
>> +       address and size */
> 
> "32 bits".
>  /* multiline comments
>   * should look like this
>   */
OK
> 
>> +    qemu_fdt_setprop_cells(fdt, node, "#size-cells", 1);
>> +    qemu_fdt_setprop_cells(fdt, node, "#address-cells", 1);
>> +    qemu_fdt_setprop_cells(fdt, node, "ranges", 0, addr >> 32, addr, size);
>> +
>> +    qemu_fdt_setprop_phandle(fdt, node, "interrupt-parent", intc);
>> +
>> +    dev = qdev_find_recursive(sysbus_get_default(), 
>> TYPE_PLATFORM_BUS_DEVICE);
>> +    pbus = PLATFORM_BUS_DEVICE(dev);
>> +
>> +    /* We can only create dt nodes for dynamic devices when they're ready */
>> +    if (pbus->done_gathering) {
> 
> Isn't it a bug if we get here with done_gathering false? If not,
> then what arranges for us to get called again later?
Yes it would be bug in the board model. The "gathering" is done in the
notifier registered in platform_bus_realize while this function is
executed in the notifier registered in create_platform_bus, when calling
arm_register_platform_bus_fdt_creator. create_platform_bus takes care of
registering the fdt creator notifier first and then instantiating the
platform bus.

I will put an assert then.

Thanks for the review!

Best Regards

Eric
> 
>> +        PlatformBusFdtData data = {
>> +            .fdt = fdt,
>> +            .irq_start = irq_start,
>> +            .pbus_node_name = node,
>> +            .pbus = pbus,
>> +        };
>> +
>> +        /* Loop through all dynamic sysbus devices and create their node */
>> +        foreach_dynamic_sysbus_device(add_fdt_node, &data);
>> +    }
>> +
>> +    g_free(node);
>> +}
> 
> Rest looks OK I think.
> 
> -- PMM
>