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Date:   Tue, 17 Jan 2023 08:20:37 -0600
From:   Rob Herring <robh@kernel.org>
To:     Saurabh Sengar <ssengar@linux.microsoft.com>
Cc:     krzysztof.kozlowski+dt@linaro.org, kys@microsoft.com,
        haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com,
        daniel.lezcano@linaro.org, tglx@linutronix.de,
        devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-hyperv@vger.kernel.org, mikelley@microsoft.com,
        ssengar@microsoft.com
Subject: Re: [PATCH 3/4] Drivers: hv: vmbus: Device Tree support
Message-ID: <20230117142037.GA2995150-robh@kernel.org>
References: <1673887688-19151-1-git-send-email-ssengar@linux.microsoft.com>
 <1673887688-19151-4-git-send-email-ssengar@linux.microsoft.com>
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On Mon, Jan 16, 2023 at 08:48:07AM -0800, 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.
> 
> When built for OF, the driver registers as a platform driver and includes
> a 'of' probe function that is alternate to the existing ACPI registration
> and probe when built for ACPI. The VMBus driver maintains its registration
> as the bus that other VMBus devices plug into, regardless of whether it is
> initially probed and initialized via ACPI or OF.
> 
> This change also introduce vmbus_remove_mmio function, which helps removing
> the duplicate code for mmio cleanup between APIC and OF driver.
> 
> Signed-off-by: Saurabh Sengar <ssengar@linux.microsoft.com>
> ---
>  drivers/hv/vmbus_drv.c | 190 ++++++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 155 insertions(+), 35 deletions(-)
> 
> diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
> index 1901556..894b360 100644
> --- a/drivers/hv/vmbus_drv.c
> +++ b/drivers/hv/vmbus_drv.c
> @@ -11,11 +11,13 @@
>  
>  #include <linux/init.h>
>  #include <linux/module.h>
> -#include <linux/device.h>
> +#include <linux/platform_device.h>
>  #include <linux/interrupt.h>
>  #include <linux/sysctl.h>
>  #include <linux/slab.h>
>  #include <linux/acpi.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
>  #include <linux/completion.h>
>  #include <linux/hyperv.h>
>  #include <linux/kernel_stat.h>
> @@ -44,14 +46,14 @@ struct vmbus_dynid {
>  	struct hv_vmbus_device_id id;
>  };
>  
> -static struct acpi_device  *hv_acpi_dev;
> -
>  static int hyperv_cpuhp_online;
>  
>  static void *hv_panic_page;
>  
>  static long __percpu *vmbus_evt;
>  
> +static struct device *vmbus_root_dev;
> +
>  /* Values parsed from ACPI DSDT */
>  int vmbus_irq;
>  int vmbus_interrupt;
> @@ -136,17 +138,13 @@ static int hv_die_panic_notify_crash(struct notifier_block *self,
>  	return NOTIFY_DONE;
>  }
>  
> -static const char *fb_mmio_name = "fb_range";
>  static struct resource *fb_mmio;
>  static struct resource *hyperv_mmio;
>  static DEFINE_MUTEX(hyperv_mmio_lock);
>  
>  static int vmbus_exists(void)
>  {
> -	if (hv_acpi_dev == NULL)
> -		return -ENODEV;
> -
> -	return 0;
> +	return vmbus_root_dev ? 0 : -ENODEV;
>  }
>  
>  static u8 channel_monitor_group(const struct vmbus_channel *channel)
> @@ -932,7 +930,7 @@ static int vmbus_dma_configure(struct device *child_device)
>  	 * On x86/x64 coherence is assumed and these calls have no effect.
>  	 */
>  	hv_setup_dma_ops(child_device,
> -		device_get_dma_attr(&hv_acpi_dev->dev) == DEV_DMA_COHERENT);
> +		device_get_dma_attr(vmbus_root_dev) == DEV_DMA_COHERENT);
>  	return 0;
>  }
>  
> @@ -2090,7 +2088,7 @@ int vmbus_device_register(struct hv_device *child_device_obj)
>  		     &child_device_obj->channel->offermsg.offer.if_instance);
>  
>  	child_device_obj->device.bus = &hv_bus;
> -	child_device_obj->device.parent = &hv_acpi_dev->dev;
> +	child_device_obj->device.parent = vmbus_root_dev;
>  	child_device_obj->device.release = vmbus_device_release;
>  
>  	child_device_obj->device.dma_parms = &child_device_obj->dma_parms;
> @@ -2151,7 +2149,26 @@ void vmbus_device_unregister(struct hv_device *device_obj)
>  	device_unregister(&device_obj->device);
>  }
>  
> +static void vmbus_remove_mmio(void)
> +{
> +	struct resource *cur_res;
> +	struct resource *next_res;
> +
> +	if (hyperv_mmio) {
> +		if (fb_mmio) {
> +			__release_region(hyperv_mmio, fb_mmio->start,
> +					 resource_size(fb_mmio));
> +			fb_mmio = NULL;
> +		}
> +
> +		for (cur_res = hyperv_mmio; cur_res; cur_res = next_res) {
> +			next_res = cur_res->sibling;
> +			kfree(cur_res);
> +		}
> +	}
> +}
>  
> +#ifdef CONFIG_ACPI
>  /*
>   * VMBUS is an acpi enumerated device. Get the information we
>   * need from DSDT.
> @@ -2264,21 +2281,7 @@ static acpi_status vmbus_walk_resources(struct acpi_resource *res, void *ctx)
>  
>  static void vmbus_acpi_remove(struct acpi_device *device)
>  {
> -	struct resource *cur_res;
> -	struct resource *next_res;
> -
> -	if (hyperv_mmio) {
> -		if (fb_mmio) {
> -			__release_region(hyperv_mmio, fb_mmio->start,
> -					 resource_size(fb_mmio));
> -			fb_mmio = NULL;
> -		}
> -
> -		for (cur_res = hyperv_mmio; cur_res; cur_res = next_res) {
> -			next_res = cur_res->sibling;
> -			kfree(cur_res);
> -		}
> -	}
> +	vmbus_remove_mmio();
>  }
>  
>  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);
>  }
> +#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);

These are all standard properties, so you shouldn't be parsing them 
yourself. Likely you are doing it wrong. For example, where do you 
handle address translations in parent nodes?

Use or add to what is in drivers/of/address.c.


> +		pr_debug("VMBUS DeviceTree MMIO region start %#llx, %#x\n", start, len);
> +
> +		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,
>  	.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",
> +		.compatible = "msft,vmbus",
> +		.data = NULL
> +	},
> +	{
> +		/* 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
> +
> +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

Use 'if (IS_ENABLED(CONFIG_ACPI))' here and anywhere else you can.

Rob