[PATCH kvmtool 02/21] hw/serial: Use device abstraction for FDT generator function

[Alexandru Elisei]

Hi Andre,

On 12/10/20 2:28 PM, Andre Przywara wrote:
> At the moment we use the .generate_fdt_node member of the ioport ops
> structure to store the function pointer for the FDT node generator
> function. ioport__register() will then put a wrapper and this pointer
> into the device header.
> The serial device is the only device making use of this special ioport
> feature, so let's move this over to using the device header directly.
>
> This will allow us to get rid of this .generate_fdt_node member in the
> ops and simplify the code.
>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> ---
>  hw/serial.c       | 49 +++++++++++++++++++++++++++++++++++++----------
>  include/kvm/kvm.h |  2 ++
>  2 files changed, 41 insertions(+), 10 deletions(-)
>
> diff --git a/hw/serial.c b/hw/serial.c
> index 13c4663e..b0465d99 100644
> --- a/hw/serial.c
> +++ b/hw/serial.c
> @@ -23,6 +23,7 @@
>  #define UART_IIR_TYPE_BITS	0xc0
>  
>  struct serial8250_device {
> +	struct device_header	dev_hdr;
>  	struct mutex		mutex;
>  	u8			id;
>  
> @@ -53,9 +54,20 @@ struct serial8250_device {
>  	.msr			= UART_MSR_DCD | UART_MSR_DSR | UART_MSR_CTS, \
>  	.mcr			= UART_MCR_OUT2,
>  
> +#ifdef CONFIG_HAS_LIBFDT
> +static
> +void serial8250_generate_fdt_node(void *fdt, struct device_header *dev_hdr,
> +				  fdt_irq_fn irq_fn);
> +#else
> +#define serial8250_generate_fdt_node	NULL
> +#endif
>  static struct serial8250_device devices[] = {
>  	/* ttyS0 */
>  	[0]	= {
> +		.dev_hdr = {
> +			.bus_type	= DEVICE_BUS_IOPORT,
> +			.data		= serial8250_generate_fdt_node,
> +		},
>  		.mutex			= MUTEX_INITIALIZER,
>  
>  		.id			= 0,
> @@ -66,6 +78,10 @@ static struct serial8250_device devices[] = {
>  	},
>  	/* ttyS1 */
>  	[1]	= {
> +		.dev_hdr = {
> +			.bus_type	= DEVICE_BUS_IOPORT,
> +			.data		= serial8250_generate_fdt_node,
> +		},
>  		.mutex			= MUTEX_INITIALIZER,
>  
>  		.id			= 1,
> @@ -76,6 +92,10 @@ static struct serial8250_device devices[] = {
>  	},
>  	/* ttyS2 */
>  	[2]	= {
> +		.dev_hdr = {
> +			.bus_type	= DEVICE_BUS_IOPORT,
> +			.data		= serial8250_generate_fdt_node,
> +		},
>  		.mutex			= MUTEX_INITIALIZER,
>  
>  		.id			= 2,
> @@ -86,6 +106,10 @@ static struct serial8250_device devices[] = {
>  	},
>  	/* ttyS3 */
>  	[3]	= {
> +		.dev_hdr = {
> +			.bus_type	= DEVICE_BUS_IOPORT,
> +			.data		= serial8250_generate_fdt_node,
> +		},
>  		.mutex			= MUTEX_INITIALIZER,
>  
>  		.id			= 3,
> @@ -371,13 +395,14 @@ char *fdt_stdout_path = NULL;
>  
>  #define DEVICE_NAME_MAX_LEN 32
>  static
> -void serial8250_generate_fdt_node(struct ioport *ioport, void *fdt,
> -				  void (*generate_irq_prop)(void *fdt,
> -							    u8 irq,
> -							    enum irq_type))
> +void serial8250_generate_fdt_node(void *fdt, struct device_header *dev_hdr,
> +				  fdt_irq_fn irq_fn)
>  {
>  	char dev_name[DEVICE_NAME_MAX_LEN];
> -	struct serial8250_device *dev = ioport->priv;
> +	struct serial8250_device *dev = container_of(dev_hdr,
> +						     struct serial8250_device,
> +						     dev_hdr);
> +
>  	u64 addr = KVM_IOPORT_AREA + dev->iobase;
>  	u64 reg_prop[] = {
>  		cpu_to_fdt64(addr),
> @@ -395,24 +420,26 @@ void serial8250_generate_fdt_node(struct ioport *ioport, void *fdt,
>  	_FDT(fdt_begin_node(fdt, dev_name));
>  	_FDT(fdt_property_string(fdt, "compatible", "ns16550a"));
>  	_FDT(fdt_property(fdt, "reg", reg_prop, sizeof(reg_prop)));
> -	generate_irq_prop(fdt, dev->irq, IRQ_TYPE_LEVEL_HIGH);
> +	irq_fn(fdt, dev->irq, IRQ_TYPE_LEVEL_HIGH);
>  	_FDT(fdt_property_cell(fdt, "clock-frequency", 1843200));
>  	_FDT(fdt_end_node(fdt));
>  }
> -#else
> -#define serial8250_generate_fdt_node	NULL
>  #endif
>  
>  static struct ioport_operations serial8250_ops = {
>  	.io_in			= serial8250_in,
>  	.io_out			= serial8250_out,
> -	.generate_fdt_node	= serial8250_generate_fdt_node,
>  };
>  
> -static int serial8250__device_init(struct kvm *kvm, struct serial8250_device *dev)
> +static int serial8250__device_init(struct kvm *kvm,
> +				   struct serial8250_device *dev)
>  {
>  	int r;
>  
> +	r = device__register(&dev->dev_hdr);
> +	if (r < 0)
> +		return r;
> +
>  	ioport__map_irq(&dev->irq);
>  	r = ioport__register(kvm, dev->iobase, &serial8250_ops, 8, dev);

It's unfortunate that we now create two devices for one serial instance: one here,
and one created by ioport__register(). But I guess that's unavoidable in this
patch, and later patches will remove it.

>  
> @@ -438,6 +465,7 @@ cleanup:
>  		struct serial8250_device *dev = &devices[j];
>  
>  		ioport__unregister(kvm, dev->iobase);
> +		device__unregister(&dev->dev_hdr);
>  	}
>  
>  	return r;
> @@ -455,6 +483,7 @@ int serial8250__exit(struct kvm *kvm)
>  		r = ioport__unregister(kvm, dev->iobase);
>  		if (r < 0)
>  			return r;
> +		device__unregister(&dev->dev_hdr);
>  	}
>  
>  	return 0;
> diff --git a/include/kvm/kvm.h b/include/kvm/kvm.h
> index 53373b08..ee99c28e 100644
> --- a/include/kvm/kvm.h
> +++ b/include/kvm/kvm.h
> @@ -31,6 +31,8 @@
>  	.name = #ext,			\
>  	.code = ext
>  
> +typedef void (*fdt_irq_fn)(void *fdt, u8 irq, enum irq_type);

Shouldn't that last parameter be enum irq_type irq_type? Would you consider moving
the typedef to include/kvm/fdt.h?

Other than the nitpicks above, the patch looks sound to me. I also did a quick
test by running kvm-unit-tests:

Reviewed-by: Alexandru Elisei <alexandru.elisei at arm.com>

Thanks,
Alex
> +
>  enum {
>  	KVM_VMSTATE_RUNNING,
>  	KVM_VMSTATE_PAUSED,