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Message-ID: <4CC7F3BE.5090503@ge.com>
Date: Wed, 27 Oct 2010 10:41:18 +0100
From: Martyn Welch <martyn.welch@...com>
To: "Emilio G. Cota" <cota@...ap.org>
CC: Greg KH <greg@...ah.com>, LKML <linux-kernel@...r.kernel.org>,
devel@...verdev.osuosl.org,
Juan David Gonzalez Cobas <david.cobas@...il.com>,
Bill Pemberton <wfp5p@...ginia.edu>
Subject: Re: [PATCH 04/30] staging/vme: allow non-dynamic allocation of bus
numbers
On 26/10/10 02:10, Emilio G. Cota wrote:
> From: Emilio G. Cota <cota@...ap.org>
>
> 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@...ap.org>
> ---
> 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@...com | M2 3AB VAT:GB 927559189
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