by Lokesh Vutla

[permalink] [raw]

Subject: Re: [PATCH v6 10/12] soc: ti: Add MSI domain bus support for Interrupt Aggregator

On 17/04/19 10:36 PM, Marc Zyngier wrote:
> On 17/04/2019 17:59, Lokesh Vutla wrote:
>>
>>
>> On 17/04/19 10:04 PM, Marc Zyngier wrote:
>>> On 10/04/2019 05:13, Lokesh Vutla wrote:
>>>> With the system coprocessor managing the range allocation of the
>>>> inputs to Interrupt Aggregator, it is difficult to represent
>>>> the device IRQs from DT.
>>>>
>>>> The suggestion is to use MSI in such cases where devices wants
>>>> to allocate and group interrupts dynamically.
>>>>
>>>> Create a MSI domain bus layer that allocates and frees MSIs for
>>>> a device.
>>>>
>>>> APIs that are implemented:
>>>> - ti_sci_inta_msi_create_irq_domain() that creates a MSI domain
>>>> - ti_sci_inta_msi_domain_alloc_irqs() that creates MSIs for the
>>>> specified device and resource.
>>>> - ti_sci_inta_msi_domain_free_irqs() frees the irqs attached to the device.
>>>> - ti_sci_inta_msi_get_virq() for getting the virq attached to a specific event.
>>>>
>>>> Signed-off-by: Lokesh Vutla <[email protected]>
>>>> ---
>>>> Changes since v5:
>>>> - Updated the input parametes to all apis
>>>> - Updated the default chip ops.
>>>> - Prefixed all the apis with ti_sci_inta_
>>>>
>>>> Marc,
>>>> Right now ti_sci_resource is being passed for irq allocatons.
>>>> I couldn't get to use resources attached to platform_device. Because
>>>> platform_device resources are allocated in of_device_alloc() and number
>>>> of resources are fixed in it. In order to update the resources, driver
>>>> has to do a krealloc(pdev->resources) and update the num of resources.
>>>> Is it allowed to update the pdev->resources during probe time? If yes,
>>>> Ill be happy to update the patch to use platform_dev resources.
>>>
>>> My suggestion was for you to define your own bus, device type and co
>>> (much like the fsl-mc stuff), and not reuse platform devices at all.
>>>
>>>>
>>>>
>>>> MAINTAINERS | 2 +
>>>> drivers/soc/ti/Kconfig | 6 +
>>>> drivers/soc/ti/Makefile | 1 +
>>>> drivers/soc/ti/ti_sci_inta_msi.c | 167 +++++++++++++++++++++++++
>>>> include/linux/irqdomain.h | 1 +
>>>> include/linux/msi.h | 6 +
>>>> include/linux/soc/ti/ti_sci_inta_msi.h | 23 ++++
>>>> 7 files changed, 206 insertions(+)
>>>> create mode 100644 drivers/soc/ti/ti_sci_inta_msi.c
>>>> create mode 100644 include/linux/soc/ti/ti_sci_inta_msi.h
>>>>
>>>> diff --git a/MAINTAINERS b/MAINTAINERS
>>>> index ba88b3033fe4..dd31d7cb2fc6 100644
>>>> --- a/MAINTAINERS
>>>> +++ b/MAINTAINERS
>>>> @@ -15353,6 +15353,8 @@ F: Documentation/devicetree/bindings/interrupt-controller/ti,sci-intr.txt
>>>> F: Documentation/devicetree/bindings/interrupt-controller/ti,sci-inta.txt
>>>> F: drivers/irqchip/irq-ti-sci-intr.c
>>>> F: drivers/irqchip/irq-ti-sci-inta.c
>>>> +F: include/linux/soc/ti/ti_sci_inta_msi.h
>>>> +F: drivers/soc/ti/ti_sci_inta_msi.c
>>>>
>>>> Texas Instruments ASoC drivers
>>>> M: Peter Ujfalusi <[email protected]>
>>>> diff --git a/drivers/soc/ti/Kconfig b/drivers/soc/ti/Kconfig
>>>> index be4570baad96..82f110fe4953 100644
>>>> --- a/drivers/soc/ti/Kconfig
>>>> +++ b/drivers/soc/ti/Kconfig
>>>> @@ -73,4 +73,10 @@ config TI_SCI_PM_DOMAINS
>>>> called ti_sci_pm_domains. Note this is needed early in boot before
>>>> rootfs may be available.
>>>>
>>>> +config TI_SCI_INTA_MSI_DOMAIN
>>>> + bool
>>>> + select GENERIC_MSI_IRQ_DOMAIN
>>>> + help
>>>> + Driver to enable Interrupt Aggregator specific MSI Domain.
>>>> +
>>>> endif # SOC_TI
>>>> diff --git a/drivers/soc/ti/Makefile b/drivers/soc/ti/Makefile
>>>> index a22edc0b258a..b3868d392d4f 100644
>>>> --- a/drivers/soc/ti/Makefile
>>>> +++ b/drivers/soc/ti/Makefile
>>>> @@ -8,3 +8,4 @@ obj-$(CONFIG_KEYSTONE_NAVIGATOR_DMA) += knav_dma.o
>>>> obj-$(CONFIG_AMX3_PM) += pm33xx.o
>>>> obj-$(CONFIG_WKUP_M3_IPC) += wkup_m3_ipc.o
>>>> obj-$(CONFIG_TI_SCI_PM_DOMAINS) += ti_sci_pm_domains.o
>>>> +obj-$(CONFIG_TI_SCI_INTA_MSI_DOMAIN) += ti_sci_inta_msi.o
>>>> diff --git a/drivers/soc/ti/ti_sci_inta_msi.c b/drivers/soc/ti/ti_sci_inta_msi.c
>>>> new file mode 100644
>>>> index 000000000000..247a5e5f216b
>>>> --- /dev/null
>>>> +++ b/drivers/soc/ti/ti_sci_inta_msi.c
>>>> @@ -0,0 +1,167 @@
>>>> +// SPDX-License-Identifier: GPL-2.0
>>>> +/*
>>>> + * Texas Instruments' K3 Interrupt Aggregator MSI bus
>>>> + *
>>>> + * Copyright (C) 2018-2019 Texas Instruments Incorporated - http://www.ti.com/
>>>> + * Lokesh Vutla <[email protected]>
>>>> + */
>>>> +
>>>> +#include <linux/of_device.h>
>>>> +#include <linux/of_address.h>
>>>> +#include <linux/of_irq.h>
>>>> +#include <linux/irq.h>
>>>> +#include <linux/irqdomain.h>
>>>> +#include <linux/msi.h>
>>>
>>> Alphabetical ordering, please.
>>
>> Sure.
>>
>>>
>>>> +#include <linux/soc/ti/ti_sci_inta_msi.h>
>>>> +#include <linux/soc/ti/ti_sci_protocol.h>
>>>> +
>>>> +static void ti_sci_inta_msi_write_msg(struct irq_data *data,
>>>> + struct msi_msg *msg)
>>>> +{
>>>> + /* Nothing to do */
>>>> +}
>>>> +
>>>> +static void ti_sci_inta_msi_compose_msi_msg(struct irq_data *data,
>>>> + struct msi_msg *msg)
>>>> +{
>>>> + /* Nothing to do */
>>>> +}
>>>> +
>>>> +static int ti_sci_inta_msi_request_resources(struct irq_data *data)
>>>> +{
>>>> + data = data->parent_data;
>>>> +
>>>> + return data->chip->irq_request_resources(data);
>>>> +}
>>>> +
>>>> +static void ti_sci_inta_msi_release_resources(struct irq_data *data)
>>>> +{
>>>> + data = data->parent_data;
>>>> + data->chip->irq_release_resources(data);
>>>> +}
>>>
>>> The two functions above are an implementation of
>>> irq_chip_{request,release}_resource_parent(). Please make them generic
>>> functions, use them and fix drivers/gpio/gpio-thunderx.c to use them too.
>>
>> okay, will create irq_chip_{request,release}_resource_parent() apis and use them.
>>
>>>
>>>> +
>>>> +static void ti_sci_inta_msi_update_chip_ops(struct msi_domain_info *info)
>>>> +{
>>>> + struct irq_chip *chip = info->chip;
>>>> +
>>>> + WARN_ON(!chip);
>>>
>>> Just doing that isn't going to help, as you'll crash on the following
>>> line...
>>
>> Checkpatch is scribbling about it. Will use BUG_ON() in next version.
>
> Screw checkpatch, but don't use BUG_ON() either. Instead, do
>
> if (!WARN_ON(!chip))
> return;
>
>>
>>>
>>>> + if (!chip->irq_mask)
>>>> + chip->irq_mask = irq_chip_mask_parent;
>>>> + if (!chip->irq_unmask)
>>>> + chip->irq_unmask = irq_chip_unmask_parent;
>>>> + if (!chip->irq_ack)
>>>> + chip->irq_ack = irq_chip_ack_parent;
>>>> + if (!chip->irq_set_type)
>>>> + chip->irq_set_type = irq_chip_set_type_parent;
>>>> + if (!chip->irq_write_msi_msg)
>>>> + chip->irq_write_msi_msg = ti_sci_inta_msi_write_msg;
>>>> + if (!chip->irq_compose_msi_msg)
>>>> + chip->irq_compose_msi_msg = ti_sci_inta_msi_compose_msi_msg;
>>>> + if (!chip->irq_request_resources)
>>>> + chip->irq_request_resources = ti_sci_inta_msi_request_resources;
>>>> + if (!chip->irq_release_resources)
>>>> + chip->irq_release_resources = ti_sci_inta_msi_release_resources;
>>>
>>> Is there any case where a client driver wouldn't use the default all the
>>> time?
>>
>> I don't think so.
>>
>>>
>>>> +}
>>>> +
>>>> +struct irq_domain
>>>> +*ti_sci_inta_msi_create_irq_domain(struct fwnode_handle *fwnode,
>>>> + struct msi_domain_info *info,
>>>> + struct irq_domain *parent)
>>>> +{
>>>> + struct irq_domain *domain;
>>>> +
>>>> + if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
>>>> + ti_sci_inta_msi_update_chip_ops(info);
>>>
>>> If the answer above is "no", then you can happily ignore this flag and
>>> always populate the callbacks.
>>
>> Okay, will ignore the flag and populate apis.
>>
>>>
>>>> +
>>>> + domain = msi_create_irq_domain(fwnode, info, parent);
>>>> + if (domain)
>>>> + irq_domain_update_bus_token(domain, DOMAIN_BUS_TI_SCI_INTA_MSI);
>>>> +
>>>> + return domain;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(ti_sci_inta_msi_create_irq_domain);
>>>> +
>>>> +static void ti_sci_inta_msi_free_descs(struct device *dev)
>>>> +{
>>>> + struct msi_desc *desc, *tmp;
>>>> +
>>>> + list_for_each_entry_safe(desc, tmp, dev_to_msi_list(dev), list) {
>>>> + list_del(&desc->list);
>>>> + free_msi_entry(desc);
>>>> + }
>>>> +}
>>>> +
>>>> +static int ti_sci_inta_msi_alloc_descs(struct device *dev, u32 dev_id,
>>>> + struct ti_sci_resource *res)
>>>> +{
>>>> + struct msi_desc *msi_desc;
>>>> + int set, i, count = 0;
>>>> +
>>>> + for (set = 0; set < res->sets; set++) {
>>>> + for (i = 0; i < res->desc[set].num; i++) {
>>>> + msi_desc = alloc_msi_entry(dev, 1, NULL);
>>>> + if (!msi_desc) {
>>>> + ti_sci_inta_msi_free_descs(dev);
>>>> + return -ENOMEM;
>>>> + }
>>>> +
>>>> + msi_desc->inta.index = res->desc[set].start + i;
>>>> + msi_desc->inta.dev_id = dev_id;
>>>
>>> I'm highly suspiscious of this. See further down.
>>
>> I need to pass dev_id and dev_index to my irqchip driver so that hwirq gets created.
>>
>>>
>>>> + INIT_LIST_HEAD(&msi_desc->list);
>>>> + list_add_tail(&msi_desc->list, dev_to_msi_list(dev));
>>>> + count++;
>>>> + }
>>>> + }
>>>> +
>>>> + return count;
>>>> +}
>>>> +
>>>> +int ti_sci_inta_msi_domain_alloc_irqs(struct platform_device *pdev,
>>>> + struct ti_sci_resource *res)
>>>> +{
>>>> + struct irq_domain *msi_domain;
>>>> + int ret, nvec;
>>>> +
>>>> + msi_domain = dev_get_msi_domain(&pdev->dev);
>>>> + if (!msi_domain)
>>>> + return -EINVAL;
>>>> +
>>>> + if (pdev->id < 0)
>>>> + return -ENODEV;
>>>> +
>>>> + nvec = ti_sci_inta_msi_alloc_descs(&pdev->dev, pdev->id, res);
>>>> + if (nvec <= 0)
>>>> + return nvec;
>>>> +
>>>> + ret = msi_domain_alloc_irqs(msi_domain, &pdev->dev, nvec);
>>>> + if (ret) {
>>>> + dev_err(&pdev->dev, "Failed to allocate IRQs %d\n", ret);
>>>> + goto cleanup;
>>>> + }
>>>> +
>>>> + return 0;
>>>> +
>>>> +cleanup:
>>>> + ti_sci_inta_msi_free_descs(&pdev->dev);
>>>> + return ret;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(ti_sci_inta_msi_domain_alloc_irqs);
>>>> +
>>>> +void ti_sci_inta_msi_domain_free_irqs(struct device *dev)
>>>> +{
>>>> + msi_domain_free_irqs(dev->msi_domain, dev);
>>>> + ti_sci_inta_msi_free_descs(dev);
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(ti_sci_inta_msi_domain_free_irqs);
>>>> +
>>>> +unsigned int ti_sci_inta_msi_get_virq(struct platform_device *pdev, u32 index)
>>>> +{
>>>> + struct msi_desc *desc;
>>>> +
>>>> + for_each_msi_entry(desc, &pdev->dev)
>>>> + if (desc->inta.index == index && desc->inta.dev_id == pdev->id)
>>>
>>> What is this "index"? Why isn't the right entry the index-th element in
>>> the msi_desc list? Worse, the dev_id check. The whole point of having a
>>> per-device MSI list is that it is, well, per device.
>>
>> Might be wrong choice of word here. As you know, dev_index need not be
>> contiguous. ti_sci_resource will have the range of dev_index allocated to the
>> linux host. using this dev_index irqs gets configured. Even the client drivers
>> only track this dev_index. Isn't it correct to use this dev_index to translate
>> to virq?
>
> OK. But what about the dev_id check? Surely all the MSIs allocated to a
> single device have the same devid, right? and that id is equal to pdev->id?

yeah, I can drop the dev_id check.

Thanks and regards,
Lokesh

>
> Thanks,
>
> M.
>