Re: [PATCH 04/30] staging/vme: allow non-dynamic allocation of busnumbers

[Martyn Welch]

On 26/10/10 02:10, Emilio G. Cota wrote:
> From: Emilio G. Cota <cota@xxxxxxxxx>
> 
> In a configuration with several bridges, each bridge is
> assigned a certain bus number depending on the order in which
> vme_register_bridge is called. This can complicate multi-bridge
> installations because the eventual bus numbers will depend
> on the order the bridges were loaded.
> 
> The appended allows bridges to register with a bus number of
> their choice, while keeping the previous 'first come, first
> served' behaviour as the default.
> 

I can't see where this is being used. I assume this is a part of future
changes you wish to make?

Martyn

> Signed-off-by: Emilio G. Cota <cota@xxxxxxxxx>
> ---
>  drivers/staging/vme/bridges/vme_ca91cx42.c |    1 +
>  drivers/staging/vme/bridges/vme_tsi148.c   |    1 +
>  drivers/staging/vme/vme.c                  |   46 +++++++++++++++++++++-------
>  drivers/staging/vme/vme.h                  |    1 +
>  4 files changed, 38 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/staging/vme/bridges/vme_ca91cx42.c b/drivers/staging/vme/bridges/vme_ca91cx42.c
> index 1f2089f..14e10a6 100644
> --- a/drivers/staging/vme/bridges/vme_ca91cx42.c
> +++ b/drivers/staging/vme/bridges/vme_ca91cx42.c
> @@ -1600,6 +1600,7 @@ static int ca91cx42_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	}
>  
>  	ca91cx42_bridge->driver_priv = ca91cx42_device;
> +	ca91cx42_bridge->num = -1;
>  
>  	/* Enable the device */
>  	retval = pci_enable_device(pdev);
> diff --git a/drivers/staging/vme/bridges/vme_tsi148.c b/drivers/staging/vme/bridges/vme_tsi148.c
> index 1cba1fa..e341122 100644
> --- a/drivers/staging/vme/bridges/vme_tsi148.c
> +++ b/drivers/staging/vme/bridges/vme_tsi148.c
> @@ -2247,6 +2247,7 @@ static int tsi148_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>  	}
>  
>  	tsi148_bridge->driver_priv = tsi148_device;
> +	tsi148_bridge->num = -1;
>  
>  	/* Enable the device */
>  	retval = pci_enable_device(pdev);
> diff --git a/drivers/staging/vme/vme.c b/drivers/staging/vme/vme.c
> index 47e9d5c..9fa0609 100644
> --- a/drivers/staging/vme/vme.c
> +++ b/drivers/staging/vme/vme.c
> @@ -1307,20 +1307,42 @@ EXPORT_SYMBOL(vme_slot_get);
>  
>  /* - Bridge Registration --------------------------------------------------- */
>  
> -static int vme_alloc_bus_num(void)
> +/* call with vme_bus_num_mtx held */
> +static int __vme_alloc_bus_num(int *bus)
>  {
> -	int i;
> -
> -	mutex_lock(&vme_bus_num_mtx);
> -	for (i = 0; i < sizeof(vme_bus_numbers) * 8; i++) {
> -		if (((vme_bus_numbers >> i) & 0x1) == 0) {
> -			vme_bus_numbers |= (0x1 << i);
> -			break;
> +	int index;
> +
> +	if (*bus == -1) {
> +		/* try to find a free bus number */
> +		for (index = 0; index < VME_MAX_BRIDGES; index++) {
> +			if (~vme_bus_numbers & 1 << index) {
> +				*bus = index;
> +				break;
> +			}
> +		}
> +		if (index == VME_MAX_BRIDGES) {
> +			pr_warn("vme: No bus numbers left\n");
> +			return -ENODEV;
> +		}
> +	} else {
> +		/* check if the given bus number is already in use */
> +		if (vme_bus_numbers & (1 << *bus)) {
> +			pr_warn("vme: bus number %d already in use\n", *bus);
> +			return -EBUSY;
>  		}
>  	}
> -	mutex_unlock(&vme_bus_num_mtx);
> +	vme_bus_numbers |= 1 << *bus;
> +	return 0;
> +}
> +
> +static int vme_alloc_bus_num(int *bus)
> +{
> +	int ret;
>  
> -	return i;
> +	mutex_lock(&vme_bus_num_mtx);
> +	ret = __vme_alloc_bus_num(bus);
> +	mutex_unlock(&vme_bus_num_mtx);
> +	return ret;
>  }
>  
>  static void vme_free_bus_num(int bus)
> @@ -1336,7 +1358,9 @@ int vme_register_bridge(struct vme_bridge *bridge)
>  	int retval;
>  	int i;
>  
> -	bridge->num = vme_alloc_bus_num();
> +	retval = vme_alloc_bus_num(&bridge->num);
> +	if (retval)
> +		return retval;
>  
>  	/* This creates 32 vme "slot" devices. This equates to a slot for each
>  	 * ID available in a system conforming to the ANSI/VITA 1-1994
> diff --git a/drivers/staging/vme/vme.h b/drivers/staging/vme/vme.h
> index 48768ca..5cdfa52 100644
> --- a/drivers/staging/vme/vme.h
> +++ b/drivers/staging/vme/vme.h
> @@ -88,6 +88,7 @@ struct vme_resource {
>  
>  extern struct bus_type vme_bus_type;
>  
> +#define VME_MAX_BRIDGES		32
>  #define VME_SLOT_CURRENT	-1
>  #define VME_SLOT_ALL		-2
>  


-- 
Martyn Welch (Principal Software Engineer)   |   Registered in England and
GE Intelligent Platforms                     |   Wales (3828642) at 100
T +44(0)127322748                            |   Barbirolli Square,
Manchester,
E martyn.welch@xxxxxx                        |   M2 3AB  VAT:GB 927559189
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