Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-24 Thread Logan Gunthorpe 
Hey Bjorn,

Thanks for the thorough review. It definitely helped a lot to make the
code as good as it can be.

I've made all of the changes you suggested. I'm just going to do a bit
more testing and then post a v4. See my responses to all of your
feedback bellow.

Logan

On 23/02/17 05:35 PM, Bjorn Helgaas wrote:
> Would it make any sense to integrate this with the perf tool?  It
> looks like switchtec-user measures bandwidth and latency, which sounds
> sort of perf-ish.

That would be cool but lets file that under potential future work. This
driver also enables more than bandwidth and latency so it's still
required for us.

>> +MODULE_DESCRIPTION("Microsemi Switchtec(tm) PCI-E Management Driver");
> 
> Nit: s/PCI-E/PCIe/
> 

Fixed.

>> +MODULE_VERSION("0.1");
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Microsemi Corporation");
>> +
>> +static int max_devices = 16;
> 
> This static initialization is slightly misleading because
> switchtec_init() immediately sets max_devices to at least 256.

Oops copied that from dax without thinking. I've just removed the max()
call in the init function.


>> +atomic_t event_cnt;
> 
> Why is this atomic_t?  You only do an atomic_set() (in stdev_create())
> and atomic_reads() -- no writes other than the initial one.  So I'm
> not sure what value atomic_t brings.

If you looked at a following patch in the series you'd see that there's
an atomic_inc in the ISR. The splitting of the series wasn't as precise
as it maybe should have been and thus this became a bit confusing.

>> +memcpy_fromio(stuser->data, >mmio_mrpc->output_data,
>> +  sizeof(stuser->data));
> 
> Apparently you always get 1K of data back, no matter what?

Yes, sort of unfortunately. Because these transactions can occur before
the user actually does the read, we don't know how much data the user
wants. This may be a performance improvement in the future (ie. if the
user reads before the MRPC transaction comes back, then only read the
requested amount). But we will leave it this way for now.


>> +if (!stdev_is_alive(stdev))
>> +return -ENXIO;
> 
> What exactly does this protect against?  Is it OK if stdev_is_alive()
> becomes false immediately after we check?

Yup, you're right: that's racy. Turns out cleanup is hard and I've
learned a lot even in the short time since I wrote this code. I've
gotten rid of stdev_is_alive and moved the pci cleanup code into the
device's release function so they won't occur until the last user closes
the cdev. I think that should work better but please let me know if you
see an issue with this.

>> +
>> +if (size < sizeof(stuser->cmd) ||
>> +size > sizeof(stuser->cmd) + SWITCHTEC_MRPC_PAYLOAD_SIZE)
> 
> I think I would use "sizeof(stuser->data)" instead of
> SWITCHTEC_MRPC_PAYLOAD_SIZE so it matches what mrpc_complete_cmd()
> does.  Same below in switchtec_dev_read().

Ok.

> mrpc_mutex doesn't protect the stuser things, does it?  If not, you
> could do this without the gotos.  And I think it's a little easier to
> be confident there are no buffer overruns:

I was using the mutex to protect stuser->state as well. But I've made
your changes and just adjusted stuser->state to be atomic and I think
this should be just as good.

>> +static int switchtec_init_msix_isr(struct switchtec_dev *stdev)
>> +{
>> +struct pci_dev *pdev = stdev->pdev;
>> +int rc, i, msix_count, node;
>> +
>> +node = dev_to_node(>dev);
> 
> Unused?

Yup, I've removed it.

>> +for (i = 0; i < ARRAY_SIZE(stdev->msix); ++i)
>> +stdev->msix[i].entry = i;
>> +
>> +msix_count = pci_enable_msix_range(pdev, stdev->msix, 1,
>> +   ARRAY_SIZE(stdev->msix));
>> +if (msix_count < 0)
>> +return msix_count;
> 
> Maybe this could be simplified by using pci_alloc_irq_vectors()?

Yup! I wasn't aware of that function. It's a _huge_ improvement. Thanks.
Still I'd really appreciate a quick re-review after I post v4 just to
make sure I got it correct.

>> +stdev->event_irq = ioread32(>mmio_part_cfg->vep_vector_number);
>> +if (stdev->event_irq < 0 || stdev->event_irq >= msix_count) {
>> +rc = -EFAULT;
>> +goto err_msix_request;
>> +}
> 
> Not sure what this is doing, but you immediately overwrite
> stdev->event_irq below.  If you're using it as just a temporary above
> for doing some validation, I would just use a local variable to avoid
> the connection with stdev->event_irq.

Yes, I made this temporary.

>> +stdev->event_irq = stdev->msix[stdev->event_irq].vector;
> 
> Oh, I guess you allocate several MSI-X vectors, but you only actually
> use one of them?  Why is that?  I was confused about why you allocate
> several vectors, but there's only one devm_request_irq() call below.

The event_irq is configurable in hardware and won't necessarily be the
first irq available. (It should always be in the first four.) As I
understand it, we need to allocate all of

Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-23 Thread Bjorn Helgaas 
[+cc Peter, Ingo, Arnaldo, Alexander, Christoph]

On Thu, Feb 02, 2017 at 11:06:00AM -0700, Logan Gunthorpe wrote:
> Microsemi's "Switchtec" line of PCI switch devices is already well
> supported by the kernel with standard PCI switch drivers. However, the
> Switchtec device advertises a special management endpoint with a separate
> PCI function address and class code. This endpoint enables some additional
> functionality which includes:
> 
>  * Packet and Byte Counters
>  * Switch Firmware Upgrades
>  * Event and Error logs
>  * Querying port link status
>  * Custom user firmware commands

Would it make any sense to integrate this with the perf tool?  It
looks like switchtec-user measures bandwidth and latency, which sounds
sort of perf-ish.

> This patch introduces the switchtec kernel module which provides
> PCI driver that exposes a char device. The char device provides
> userspace access to this interface through read, write and (optionally)
> poll calls.
> 
> A userspace tool and library which utilizes this interface is available
> at [1]. This tool takes inspiration (and borrows some code) from
> nvme-cli [2]. The tool is largely complete at this time but additional
> features may be added in the future.
> 
> [1] https://github.com/sbates130272/switchtec-user
> [2] https://github.com/linux-nvme/nvme-cli
> 
> Signed-off-by: Logan Gunthorpe 
> Signed-off-by: Stephen Bates 
> ---
>  MAINTAINERS|8 +
>  drivers/pci/Kconfig|1 +
>  drivers/pci/Makefile   |1 +
>  drivers/pci/switch/Kconfig |   13 +
>  drivers/pci/switch/Makefile|1 +
>  drivers/pci/switch/switchtec.c | 1028 
> 
>  6 files changed, 1052 insertions(+)
>  create mode 100644 drivers/pci/switch/Kconfig
>  create mode 100644 drivers/pci/switch/Makefile
>  create mode 100644 drivers/pci/switch/switchtec.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 5f10c28..9c35198 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -9507,6 +9507,14 @@ S: Maintained
>  F:   Documentation/devicetree/bindings/pci/aardvark-pci.txt
>  F:   drivers/pci/host/pci-aardvark.c
>  
> +PCI DRIVER FOR MICROSEMI SWITCHTEC
> +M:   Kurt Schwemmer 
> +M:   Stephen Bates 
> +M:   Logan Gunthorpe 
> +L:   linux-...@vger.kernel.org
> +S:   Maintained
> +F:   drivers/pci/switch/switchtec*
> +
>  PCI DRIVER FOR NVIDIA TEGRA
>  M:   Thierry Reding 
>  L:   linux-te...@vger.kernel.org
> diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> index 6555eb7..f72e8c5 100644
> --- a/drivers/pci/Kconfig
> +++ b/drivers/pci/Kconfig
> @@ -133,3 +133,4 @@ config PCI_HYPERV
>  
>  source "drivers/pci/hotplug/Kconfig"
>  source "drivers/pci/host/Kconfig"
> +source "drivers/pci/switch/Kconfig"
> diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
> index 8db5079..15b46dd 100644
> --- a/drivers/pci/Makefile
> +++ b/drivers/pci/Makefile
> @@ -68,3 +68,4 @@ ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG
>  
>  # PCI host controller drivers
>  obj-y += host/
> +obj-y += switch/
> diff --git a/drivers/pci/switch/Kconfig b/drivers/pci/switch/Kconfig
> new file mode 100644
> index 000..4c49648
> --- /dev/null
> +++ b/drivers/pci/switch/Kconfig
> @@ -0,0 +1,13 @@
> +menu "PCI switch controller drivers"
> + depends on PCI
> +
> +config PCI_SW_SWITCHTEC
> + tristate "MicroSemi Switchtec PCIe Switch Management Driver"
> + help
> +  Enables support for the management interface for the MicroSemi
> +  Switchtec series of PCIe switches. Supports userspace access
> +  to submit MRPC commands to the switch via /dev/switchtecX
> +  devices. See  for more
> +  information.
> +
> +endmenu
> diff --git a/drivers/pci/switch/Makefile b/drivers/pci/switch/Makefile
> new file mode 100644
> index 000..37d8cfb
> --- /dev/null
> +++ b/drivers/pci/switch/Makefile
> @@ -0,0 +1 @@
> +obj-$(CONFIG_PCI_SW_SWITCHTEC) += switchtec.o
> diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
> new file mode 100644
> index 000..e4a4294
> --- /dev/null
> +++ b/drivers/pci/switch/switchtec.c
> @@ -0,0 +1,1028 @@
> +/*
> + * Microsemi Switchtec(tm) PCIe Management Driver
> + * Copyright (c) 2017, Microsemi Corporation
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + */
> +
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +#include 
> +

Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-10 Thread Logan Gunthorpe 


On 10/02/17 10:09 AM, Greg Kroah-Hartman wrote:
> Sure, or just wait for these to be applied to the PCI tree and then send
> a follow-on patch.  It's up to Bjorn really, as to what he wants.

Ok, I sent a working follow-on patch to this thread.

@Bjorn: I'm happy to send the patches however you like. Just let me
know. If at all possible, we'd really like to see this in for the 4.11
merge window.

Thanks,

Logan
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Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-10 Thread Logan Gunthorpe 


On 10/02/17 09:55 AM, Greg Kroah-Hartman wrote:
> Yes, but try it yourself to verify it really is correct :)

Yes, of course... turns out it wasn't. I accidentally refereed to dev
before I assigned it. I had mainly just wanted your feedback to ensure
that switching to device_register made sense.

> And it can just be an add-on patch, no need to respin a whole new
> version for just that simple change, it doesn't hurt anything as-is,
> it's just "not needed".

Ok... How should I do that exactly? Attempt to reply to the thread with
another patch?

Thanks,

Logan
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Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-10 Thread Greg Kroah-Hartman 
On Fri, Feb 10, 2017 at 10:03:10AM -0700, Logan Gunthorpe wrote:
> 
> 
> On 10/02/17 09:55 AM, Greg Kroah-Hartman wrote:
> > Yes, but try it yourself to verify it really is correct :)
> 
> Yes, of course... turns out it wasn't. I accidentally refereed to dev
> before I assigned it. I had mainly just wanted your feedback to ensure
> that switching to device_register made sense.
> 
> > And it can just be an add-on patch, no need to respin a whole new
> > version for just that simple change, it doesn't hurt anything as-is,
> > it's just "not needed".
> 
> Ok... How should I do that exactly? Attempt to reply to the thread with
> another patch?

Sure, or just wait for these to be applied to the PCI tree and then send
a follow-on patch.  It's up to Bjorn really, as to what he wants.

thanks,

greg k-h
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Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-10 Thread Greg Kroah-Hartman 
On Fri, Feb 10, 2017 at 09:48:37AM -0700, Logan Gunthorpe wrote:
> Hey Greg,
> 
> Thanks so much for the review.
> 
> On 10/02/17 07:51 AM, Greg Kroah-Hartman wrote:
> > On Thu, Feb 02, 2017 at 11:06:00AM -0700, Logan Gunthorpe wrote:
> >> +  cdev = >cdev;
> >> +  cdev_init(cdev, _fops);
> >> +  cdev->owner = THIS_MODULE;
> >> +  cdev->kobj.parent = >kobj;
> > 
> > Minor nit, the kobject in a cdev is unlike any other kobject you have
> > ever seen, don't mess with it, it's not doing anything like you think it
> > is doing.  So no need to set the parent field.
> 
> Ok, that makes sense. I'll do a v3 shortly.
> 
> I copied this from drivers/dax/dax.c so when I have a spare moment I'll
> submit a patch to remove it from there as well.
> 
> Just to make sure I get this right without extra churn: does this look
> correct?
> 
> 
> cdev = >cdev;
> cdev_init(cdev, _fops);
> cdev->owner = THIS_MODULE;
> 
> rc = cdev_add(>cdev, dev->devt, 1);
> if (rc)
> goto err_cdev;
> 
> dev = >dev;
> dev->devt = MKDEV(MAJOR(switchtec_devt), minor);
> dev->class = switchtec_class;
> dev->parent = >dev;
> dev->groups = switchtec_device_groups;
> dev->release = stdev_release;
> dev_set_name(dev, "switchtec%d", minor);
> 
> rc = device_register(dev);
> if (rc) {
> cdev_del(>cdev);
> put_device(dev);
> return ERR_PTR(rc);
> }
> 

Yes, but try it yourself to verify it really is correct :)

And it can just be an add-on patch, no need to respin a whole new
version for just that simple change, it doesn't hurt anything as-is,
it's just "not needed".

thanks,

greg k-h
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Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-10 Thread Logan Gunthorpe 
Hey Greg,

Thanks so much for the review.

On 10/02/17 07:51 AM, Greg Kroah-Hartman wrote:
> On Thu, Feb 02, 2017 at 11:06:00AM -0700, Logan Gunthorpe wrote:
>> +cdev = >cdev;
>> +cdev_init(cdev, _fops);
>> +cdev->owner = THIS_MODULE;
>> +cdev->kobj.parent = >kobj;
> 
> Minor nit, the kobject in a cdev is unlike any other kobject you have
> ever seen, don't mess with it, it's not doing anything like you think it
> is doing.  So no need to set the parent field.

Ok, that makes sense. I'll do a v3 shortly.

I copied this from drivers/dax/dax.c so when I have a spare moment I'll
submit a patch to remove it from there as well.

Just to make sure I get this right without extra churn: does this look
correct?


cdev = >cdev;
cdev_init(cdev, _fops);
cdev->owner = THIS_MODULE;

rc = cdev_add(>cdev, dev->devt, 1);
if (rc)
goto err_cdev;

dev = >dev;
dev->devt = MKDEV(MAJOR(switchtec_devt), minor);
dev->class = switchtec_class;
dev->parent = >dev;
dev->groups = switchtec_device_groups;
dev->release = stdev_release;
dev_set_name(dev, "switchtec%d", minor);

rc = device_register(dev);
if (rc) {
cdev_del(>cdev);
put_device(dev);
return ERR_PTR(rc);
}


Thanks,

Logan
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Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-10 Thread Greg Kroah-Hartman 
On Thu, Feb 02, 2017 at 11:06:00AM -0700, Logan Gunthorpe wrote:
> Microsemi's "Switchtec" line of PCI switch devices is already well
> supported by the kernel with standard PCI switch drivers. However, the
> Switchtec device advertises a special management endpoint with a separate
> PCI function address and class code. This endpoint enables some additional
> functionality which includes:
> 
>  * Packet and Byte Counters
>  * Switch Firmware Upgrades
>  * Event and Error logs
>  * Querying port link status
>  * Custom user firmware commands
> 
> This patch introduces the switchtec kernel module which provides
> PCI driver that exposes a char device. The char device provides
> userspace access to this interface through read, write and (optionally)
> poll calls.
> 
> A userspace tool and library which utilizes this interface is available
> at [1]. This tool takes inspiration (and borrows some code) from
> nvme-cli [2]. The tool is largely complete at this time but additional
> features may be added in the future.
> 
> [1] https://github.com/sbates130272/switchtec-user
> [2] https://github.com/linux-nvme/nvme-cli
> 
> Signed-off-by: Logan Gunthorpe 
> Signed-off-by: Stephen Bates 

Reviewed-by: Greg Kroah-Hartman 
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Re: [PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-10 Thread Greg Kroah-Hartman 
On Thu, Feb 02, 2017 at 11:06:00AM -0700, Logan Gunthorpe wrote:
> + cdev = >cdev;
> + cdev_init(cdev, _fops);
> + cdev->owner = THIS_MODULE;
> + cdev->kobj.parent = >kobj;

Minor nit, the kobject in a cdev is unlike any other kobject you have
ever seen, don't mess with it, it's not doing anything like you think it
is doing.  So no need to set the parent field.

thanks,

greg k-h
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[PATCH v2 1/4] MicroSemi Switchtec management interface driver

2017-02-02 Thread Logan Gunthorpe 
Microsemi's "Switchtec" line of PCI switch devices is already well
supported by the kernel with standard PCI switch drivers. However, the
Switchtec device advertises a special management endpoint with a separate
PCI function address and class code. This endpoint enables some additional
functionality which includes:

 * Packet and Byte Counters
 * Switch Firmware Upgrades
 * Event and Error logs
 * Querying port link status
 * Custom user firmware commands

This patch introduces the switchtec kernel module which provides
PCI driver that exposes a char device. The char device provides
userspace access to this interface through read, write and (optionally)
poll calls.

A userspace tool and library which utilizes this interface is available
at [1]. This tool takes inspiration (and borrows some code) from
nvme-cli [2]. The tool is largely complete at this time but additional
features may be added in the future.

[1] https://github.com/sbates130272/switchtec-user
[2] https://github.com/linux-nvme/nvme-cli

Signed-off-by: Logan Gunthorpe 
Signed-off-by: Stephen Bates 
---
 MAINTAINERS|8 +
 drivers/pci/Kconfig|1 +
 drivers/pci/Makefile   |1 +
 drivers/pci/switch/Kconfig |   13 +
 drivers/pci/switch/Makefile|1 +
 drivers/pci/switch/switchtec.c | 1028 
 6 files changed, 1052 insertions(+)
 create mode 100644 drivers/pci/switch/Kconfig
 create mode 100644 drivers/pci/switch/Makefile
 create mode 100644 drivers/pci/switch/switchtec.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 5f10c28..9c35198 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -9507,6 +9507,14 @@ S:   Maintained
 F: Documentation/devicetree/bindings/pci/aardvark-pci.txt
 F: drivers/pci/host/pci-aardvark.c
 
+PCI DRIVER FOR MICROSEMI SWITCHTEC
+M: Kurt Schwemmer 
+M: Stephen Bates 
+M: Logan Gunthorpe 
+L: linux-...@vger.kernel.org
+S: Maintained
+F: drivers/pci/switch/switchtec*
+
 PCI DRIVER FOR NVIDIA TEGRA
 M: Thierry Reding 
 L: linux-te...@vger.kernel.org
diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
index 6555eb7..f72e8c5 100644
--- a/drivers/pci/Kconfig
+++ b/drivers/pci/Kconfig
@@ -133,3 +133,4 @@ config PCI_HYPERV
 
 source "drivers/pci/hotplug/Kconfig"
 source "drivers/pci/host/Kconfig"
+source "drivers/pci/switch/Kconfig"
diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
index 8db5079..15b46dd 100644
--- a/drivers/pci/Makefile
+++ b/drivers/pci/Makefile
@@ -68,3 +68,4 @@ ccflags-$(CONFIG_PCI_DEBUG) := -DDEBUG
 
 # PCI host controller drivers
 obj-y += host/
+obj-y += switch/
diff --git a/drivers/pci/switch/Kconfig b/drivers/pci/switch/Kconfig
new file mode 100644
index 000..4c49648
--- /dev/null
+++ b/drivers/pci/switch/Kconfig
@@ -0,0 +1,13 @@
+menu "PCI switch controller drivers"
+   depends on PCI
+
+config PCI_SW_SWITCHTEC
+   tristate "MicroSemi Switchtec PCIe Switch Management Driver"
+   help
+Enables support for the management interface for the MicroSemi
+Switchtec series of PCIe switches. Supports userspace access
+to submit MRPC commands to the switch via /dev/switchtecX
+devices. See  for more
+information.
+
+endmenu
diff --git a/drivers/pci/switch/Makefile b/drivers/pci/switch/Makefile
new file mode 100644
index 000..37d8cfb
--- /dev/null
+++ b/drivers/pci/switch/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_PCI_SW_SWITCHTEC) += switchtec.o
diff --git a/drivers/pci/switch/switchtec.c b/drivers/pci/switch/switchtec.c
new file mode 100644
index 000..e4a4294
--- /dev/null
+++ b/drivers/pci/switch/switchtec.c
@@ -0,0 +1,1028 @@
+/*
+ * Microsemi Switchtec(tm) PCIe Management Driver
+ * Copyright (c) 2017, Microsemi Corporation
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+#include 
+
+MODULE_DESCRIPTION("Microsemi Switchtec(tm) PCI-E Management Driver");
+MODULE_VERSION("0.1");
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Microsemi Corporation");
+
+static int max_devices = 16;
+module_param(max_devices, int, 0644);
+MODULE_PARM_DESC(max_devices, "max number of switchtec device instances");
+
+static dev_t switchtec_devt;
+static struct class *switchtec_class;
+static DEFINE_IDA(switchtec_minor_ida);
+
+#define MICROSEMI_VENDOR_ID 0x11f8
+#define MICROSEMI_NTB_CLASSCODE