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Message-ID: <20230201090357.GA22253@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
Date: Wed, 1 Feb 2023 01:03:57 -0800
From: Saurabh Singh Sengar <ssengar@...ux.microsoft.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
kys@...rosoft.com, haiyangz@...rosoft.com, wei.liu@...nel.org,
decui@...rosoft.com, daniel.lezcano@...aro.org, tglx@...utronix.de,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-hyperv@...r.kernel.org, mikelley@...rosoft.com,
ssengar@...rosoft.com
Subject: Re: [PATCH 3/4] Drivers: hv: vmbus: Device Tree support
On Mon, Jan 16, 2023 at 07:48:25PM +0100, Krzysztof Kozlowski wrote:
> On 16/01/2023 17:48, Saurabh Sengar wrote:
> > Update the driver to use vmbus_root_dev device instead of acpi_device,
> > which can be assigned to either ACPI or OF device, making VMBus agnostic
> > to whether the device is using ACPI or device tree.
> >
>
> (...)
>
> >
> > static void vmbus_reserve_fb(void)
> > @@ -2319,8 +2322,9 @@ static void vmbus_reserve_fb(void)
> > * reserving a larger area and make it smaller until it succeeds.
> > */
> > for (; !fb_mmio && (size >= 0x100000); size >>= 1)
> > - fb_mmio = __request_region(hyperv_mmio, start, size, fb_mmio_name, 0);
> > + fb_mmio = __request_region(hyperv_mmio, start, size, "fb_range", 0);
>
> Your patch is doing much more than just adding OF. Adding OF is usually
> just few lines, so this means you are refactoring driver and all this
> work should be split to self-contained patches.
did a split in v2.
>
> > }
> > +#endif /* CONFIG_ACPI */
> >
> > /**
> > * vmbus_allocate_mmio() - Pick a memory-mapped I/O range.
> > @@ -2441,13 +2445,14 @@ void vmbus_free_mmio(resource_size_t start, resource_size_t size)
> > }
> > EXPORT_SYMBOL_GPL(vmbus_free_mmio);
> >
> > +#ifdef CONFIG_ACPI
> > static int vmbus_acpi_add(struct acpi_device *device)
> > {
> > acpi_status result;
> > int ret_val = -ENODEV;
> > struct acpi_device *ancestor;
> >
> > - hv_acpi_dev = device;
> > + vmbus_root_dev = &device->dev;
> >
> > /*
> > * Older versions of Hyper-V for ARM64 fail to include the _CCA
> > @@ -2492,6 +2497,72 @@ static int vmbus_acpi_add(struct acpi_device *device)
> > vmbus_acpi_remove(device);
> > return ret_val;
> > }
> > +#endif
> > +
> > +#ifdef CONFIG_OF
> > +static int vmbus_of_driver_probe(struct platform_device *dev)
> > +{
> > + struct resource **cur_res = &hyperv_mmio;
> > + struct device_node *np;
> > + const __be32 *ranges;
> > + u32 nr_addr, nr_size, nr_parent_addr_cells, nr_ranges;
> > + u32 range_len, range_size;
> > + int i;
> > +
> > + vmbus_root_dev = &dev->dev;
> > + np = vmbus_root_dev->of_node;
> > +
> > + if (of_property_read_u32(np, "#address-cells", &nr_addr))
> > + return -ENOENT;
> > + if (of_property_read_u32(np, "#size-cells", &nr_size))
> > + return -ENOENT;
> > + nr_parent_addr_cells = of_n_addr_cells(np);
> > +
> > + if (nr_parent_addr_cells != 2 || nr_addr != 2 || nr_size != 1) {
> > + pr_err("Address format is not supported\n");
> > + return -EINVAL;
> > + }
> > +
> > + ranges = of_get_property(np, "ranges", &range_len);
> > + if (!ranges)
> > + return -ENOENT;
> > +
> > + range_size = nr_parent_addr_cells + nr_addr + nr_size; // in cells
> > + nr_ranges = range_len / sizeof(__be32) / range_size;
> > +
> > + for (i = 0; i < nr_ranges; ++i, ranges += range_size) {
> > + struct resource *res;
> > + /*
> > + * The first u64 in the ranges description isn't used currently.
> > + * u64 _ = of_read_number(ranges, nr_parent_addr_cells);
> > + */
> > + u64 start = of_read_number(ranges + nr_parent_addr_cells, nr_addr);
> > + u32 len = of_read_number(ranges + nr_parent_addr_cells + nr_addr, nr_size);
> > +
> > + pr_debug("VMBUS DeviceTree MMIO region start %#llx, %#x\n", start, len);
>
> You must not print kernel or IO space addresses. You could use some
> printk formats to hide the address, if this is really needed.
removed in v2
>
> > +
> > + res = kzalloc(sizeof(*res), GFP_ATOMIC);
> > + if (!res)
> > + return -ENOMEM;
> > +
> > + res->name = "hyperv mmio";
> > + res->flags = IORESOURCE_MEM | IORESOURCE_MEM_64;
> > + res->start = start;
> > + res->end = start + len;
> > +
> > + *cur_res = res;
> > + cur_res = &res->sibling;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int vmbus_of_driver_remove(struct platform_device *dev)
> > +{
> > + vmbus_remove_mmio();
> > + return 0;
> > +}
> > +#endif
> >
> > #ifdef CONFIG_PM_SLEEP
> > static int vmbus_bus_suspend(struct device *dev)
> > @@ -2630,6 +2701,9 @@ static int vmbus_bus_resume(struct device *dev)
> > #define vmbus_bus_resume NULL
> > #endif /* CONFIG_PM_SLEEP */
> >
> > +#define DRV_NAME "vmbus"
> > +
> > +#ifdef CONFIG_ACPI
> > static const struct acpi_device_id vmbus_acpi_device_ids[] = {
> > {"VMBUS", 0},
> > {"VMBus", 0},
> > @@ -2659,7 +2733,7 @@ static int vmbus_bus_resume(struct device *dev)
> > };
> >
> > static struct acpi_driver vmbus_acpi_driver = {
> > - .name = "vmbus",
> > + .name = DRV_NAME,
>
> How this is related?
removed in v2
>
> > .ids = vmbus_acpi_device_ids,
> > .ops = {
> > .add = vmbus_acpi_add,
> > @@ -2669,6 +2743,7 @@ static int vmbus_bus_resume(struct device *dev)
> > .drv.probe_type = PROBE_FORCE_SYNCHRONOUS,
> > };
> >
> > +#endif
> > static void hv_kexec_handler(void)
> > {
> > hv_stimer_global_cleanup();
> > @@ -2737,7 +2812,32 @@ static void hv_synic_resume(void)
> > .resume = hv_synic_resume,
> > };
> >
> > -static int __init hv_acpi_init(void)
> > +#ifdef CONFIG_OF
> > +static const struct of_device_id vmbus_of_match[] = {
> > + {
> > + .name = "msft,vmbus",
>
> Why do you need name?
removed in v2.
>
> > + .compatible = "msft,vmbus",
> > + .data = NULL
>
> Why do you need data field?
removed in v2
>
> > + },
> > + {
> > + /* sentinel */
> > + },
> > +};
> > +MODULE_DEVICE_TABLE(of, vmbus_of_match);
> > +
> > +static struct platform_driver vmbus_platform_driver = {
> > + .probe = vmbus_of_driver_probe,
> > + .remove = vmbus_of_driver_remove,
> > + .driver = {
> > + .name = DRV_NAME,
> > + .of_match_table = of_match_ptr(vmbus_of_match),
> > + .pm = &vmbus_pm,
> > + .bus = &hv_bus,
> > + }
> > +};
> > +#endif
>
> Why platform driver is hidden by CONFIG_OF? It should not be the case.
> The interface - ACPI or OF - should not differ for driver
> infrastructure. Even one probe could be used - just drop all of_...
> methods and use generic device_property_
Changed the driver to platform driver as suggested and used common probe
in v2. Also using device_property_ instead of of_property.
> > +
> > +static int __init vmbus_init(void)
> > {
> > int ret;
> >
> > @@ -2747,18 +2847,27 @@ static int __init hv_acpi_init(void)
> > if (hv_root_partition && !hv_nested)
> > return 0;
> >
> > +#ifdef CONFIG_ACPI
> > /*
> > - * Get ACPI resources first.
> > + * Request ACPI resources and wait for the completion
> > */
> > ret = acpi_bus_register_driver(&vmbus_acpi_driver);
> >
> > if (ret)
> > return ret;
> >
> > - if (!hv_acpi_dev) {
> > - ret = -ENODEV;
> > + if (!vmbus_root_dev) {
> > + ret = -ETIMEDOUT;
> > goto cleanup;
> > }
> > +#endif
> > +#ifdef CONFIG_OF
> > + ret = platform_driver_register(&vmbus_platform_driver);
> > + if (ret) {
> > + pr_err("Error registering platform resources: %d\n", ret);
> > + goto cleanup;
> > + }
> > +#endif
> >
> > /*
> > * If we're on an architecture with a hardcoded hypervisor
> > @@ -2785,8 +2894,14 @@ static int __init hv_acpi_init(void)
> > return 0;
> >
> > cleanup:
> > +#ifdef CONFIG_ACPI
> > acpi_bus_unregister_driver(&vmbus_acpi_driver);
> > - hv_acpi_dev = NULL;
> > +#endif
> > +#ifdef CONFIG_OF
> > + platform_driver_unregister(&vmbus_platform_driver);
> > +#endif
> > + vmbus_root_dev = NULL;
> > +
> > return ret;
> > }
> >
> > @@ -2839,12 +2954,17 @@ static void __exit vmbus_exit(void)
> >
> > cpuhp_remove_state(hyperv_cpuhp_online);
> > hv_synic_free();
> > +#ifdef CONFIG_ACPI
> > acpi_bus_unregister_driver(&vmbus_acpi_driver);
> > +#endif
> > +#ifdef CONFIG_OF
> > + platform_driver_unregister(&vmbus_platform_driver);
> > +#endif
> > + vmbus_root_dev = NULL;
> > }
> >
> > -
>
> This is really a messy patch...
fixed in v2 with changing this driver to platform.
>
> > MODULE_LICENSE("GPL");
> > MODULE_DESCRIPTION("Microsoft Hyper-V VMBus Driver");
> >
> > -subsys_initcall(hv_acpi_init);
> > +subsys_initcall(vmbus_init);
> > module_exit(vmbus_exit);
>
> Best regards,
> Krzysztof
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