Re: [PATCH] powerpc: Add support to access the flash on SLOF based systems
On Jan 10, 2009, at 1:50 PM, Adrian Reber wrote:
On Sat, Jan 10, 2009 at 11:52:56AM -0600, Milton Miller wrote:
On Sun Jan 11 at 02:31:22 EST in 2009, Adrian Reber wrote:
This adds support for a simple character device to access the
flash for SLOF based systems like the PowerStation, QS2x and
PXCAB. In the SLOF git there is a user space program with
which the content of the flash for SLOF based systems can
be displayed and modified. This can be used to add a Linux
image to the flash and then directly boot the kernel from the
flash.
Signed-off-by: Adrian Reber adrian at lisas.de
---
This is based on the mmio NVRAM driver. I am not sure how useful this
is for anybody else but I am posting it anyway, hoping to get some
feedback. Also hoping it can be included at one point.
Normally such drivers are written and mtd drivers.
If slof were not an of implementation I would just say put the right
properties on the node in the device tree, but the kernel should adapt
to real OF. It should be easy to write a driver to hook up a mtd
platform device if this is a direct mapped flash.
The reason why I did not use mtd is that part of the flash is used by
the firmware image and I do not know if that works with mtd, if only a
part of the flash can be used. SLOF does also a CRC check over the
firmware image, so that image must have valid SLOF CRC. The flash is
a direct mapped flash, but the size of the firmware can vary.
But you later say you will only be using this driver to read the flash.
+ spin_lock_irqsave(slof_flash_lock, flags);
+
+ memcpy_fromio(tmp, slof_flash_start + *ppos, count);
+
+ spin_unlock_irqrestore(slof_flash_lock, flags);
+
Why do you need a spinlock? Why does it need to be irq safe?
I must confess I copied that code from the nvram driver and I do not
know if it is necessary.
I'm not sure which driver you ar referring to here. Which file name?
Its not required for memcpy_fromio. If you have no indirect indexing
or writing to require exclusing against concurrent access ...
This decision is also driving the malloc of the temporary buffer, and
you are intentionally returning a short read to userspace.
+
+const struct file_operations slof_flash_fops = {
+ .owner = THIS_MODULE,
+ .llseek = slof_flash_llseek,
+ .read = slof_flash_read,
+};
+
You mentioned userspace reflashing the image, but this driver seems to
be read only access.
This driver is read only. I am writing the new flash image using the
RTAS functionality to update the firmware flash. Using this device I
can
use a userspace tool to add a file to the flash. The tool puts the
result on the local filesystem. Then using the normal RTAS flash update
it can be rewritten. That way I can add a kernel (with a ramdisk) to
the
flash and then let SLOF boot that kernel. This is especially
interesting
for the PXCAB Cell based PCI Express card.
Ok you need to highlight that you will be using the platform support to
write the image. Reading the patch (again) it would appear that you
are just reading the size of the node from the device tree. Regardless
even if you are trying to cover the whole rom or a portion, read-ony
access should be safe, if not secure.
Can you identify slof from the information in the /openprom node? I
Yes I can identify SLOF from the model property in the /openprom node.
I
did not do it because there is almost no code accessing the /openprom
node and therefore I did not read it.
don't think all js20 and 21 use slof, although the IBM provided
firmware
may also work with this driver.
There are probably only very few js20/js21 which are using SLOF. I do
not think the original IBM product firmware for those blades mentions
anything about js20/js21 in the compatible node. I do not have access
to
such a system but the compatible node usually has some product number,
if I remember it correctly.
I am pretty sure that the original js20/js21 firmware does not have the
flash in the device tree, because RTAS is supposed to be the only valid
way to access the flash.
+ if ((slof_flash_len = 0) || (!slof_flash_addr)) {
+ printk(KERN_WARNING SLOF FLASH: address or length is
0\n);
+ rc = -EIO;
+ goto out;
+ }
Why are these warnings? again, debug is more approprate
Copied from the NVRAM driver. Will change it to debug.
Thanks. These would still apply to a mtd driver.
+
+ rc = misc_register(slof_flash_dev);
And as I said, this should be a mtd driver.
Thanks for the review. Should it also be a mtd driver with the firmware
at the beginning of the flash with an unknown size?
I would also prefer to continue to use the RTAS flash update
functionality to write the flash instead of reimplementing it in the
operating system.
I don't have a problem with that, but it should have been mentioned up
front.
My main motivation for this code was to have a way to access the
firmware
Re: [PATCH] powerpc: Add support to access the flash on SLOF based systems
Adrian Reber wrote: On Sat, Jan 10, 2009 at 11:52:56AM -0600, Milton Miller wrote: Normally such drivers are written and mtd drivers. If slof were not an of implementation I would just say put the right properties on the node in the device tree, but the kernel should adapt to real OF. It should be easy to write a driver to hook up a mtd platform device if this is a direct mapped flash. The reason why I did not use mtd is that part of the flash is used by the firmware image and I do not know if that works with mtd, if only a part of the flash can be used. SLOF does also a CRC check over the firmware image, so that image must have valid SLOF CRC. The flash is a direct mapped flash, but the size of the firmware can vary. It can. MTD can create partitions within the flash, for an example see lines 84-110 of arch/powerpc/bootdts/sbc8641d.dts (http://tinyurl.com/7k2kym) Partitions can also be labeled as read-only, I guess the CRC could be checked from userspace as necessary. HTH, Martyn -- Martyn Welch MEng MPhil MIET (Principal Software Engineer) T:+44(0)1327322748 GE Fanuc Intelligent Platforms Ltd,|Registered in England and Wales Tove Valley Business Park, Towcester, |(3828642) at 100 Barbirolli Square, Northants, NN12 6PF, UK T:+44(0)1327359444 |Manchester,M2 3AB VAT:GB 729849476 ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [PATCH] powerpc: Add support to access the flash on SLOF based systems
On Monday 12 January 2009, Martyn Welch wrote: Adrian Reber wrote: The reason why I did not use mtd is that part of the flash is used by the firmware image and I do not know if that works with mtd, if only a part of the flash can be used. SLOF does also a CRC check over the firmware image, so that image must have valid SLOF CRC. The flash is a direct mapped flash, but the size of the firmware can vary. It can. MTD can create partitions within the flash, for an example see lines 84-110 of arch/powerpc/bootdts/sbc8641d.dts (http://tinyurl.com/7k2kym) Partitions can also be labeled as read-only, I guess the CRC could be checked from userspace as necessary. Murali has also done a modified firmware for experiments in the past where he added the device tree entry for the flash on a PxCAB. As I recall, he did not see any problems with that. Arnd ___ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev
Re: [PATCH] powerpc: Add support to access the flash on SLOF based systems
On Sun Jan 11 at 02:31:22 EST in 2009, Adrian Reber wrote:
This adds support for a simple character device to access the
flash for SLOF based systems like the PowerStation, QS2x and
PXCAB. In the SLOF git there is a user space program with
which the content of the flash for SLOF based systems can
be displayed and modified. This can be used to add a Linux
image to the flash and then directly boot the kernel from the
flash.
Signed-off-by: Adrian Reber adrian at lisas.de
---
This is based on the mmio NVRAM driver. I am not sure how useful this
is for anybody else but I am posting it anyway, hoping to get some
feedback. Also hoping it can be included at one point.
Normally such drivers are written and mtd drivers.
If slof were not an of implementation I would just say put the right
properties on the node in the device tree, but the kernel should adapt
to real OF. It should be easy to write a driver to hook up a mtd
platform device if this is a direct mapped flash.
+
+static void __iomem *slof_flash_start;
+static long slof_flash_len;
+static DEFINE_SPINLOCK(slof_flash_lock);
+
+
+static ssize_t slof_flash_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ unsigned long flags;
+ char *tmp;
+ int rc;
+
+ spin_lock_irqsave(slof_flash_lock, flags);
+
+ memcpy_fromio(tmp, slof_flash_start + *ppos, count);
+
+ spin_unlock_irqrestore(slof_flash_lock, flags);
+
Why do you need a spinlock? Why does it need to be irq safe?
This decision is also driving the malloc of the temporary buffer, and
you are intentionally returning a short read to userspace.
+
+const struct file_operations slof_flash_fops = {
+ .owner = THIS_MODULE,
+ .llseek = slof_flash_llseek,
+ .read = slof_flash_read,
+};
+
You mentioned userspace reflashing the image, but this driver seems to
be read only access.
+static struct miscdevice slof_flash_dev = {
+ SLOF_FLASH_MINOR,
+ slof_flash,
+ slof_flash_fops
+};
+
+
+static int __init slof_flash_init(void)
+{
+ struct device_node *slof_flash;
+ struct device_node *compatible;
+ struct resource r;
+ int rc;
+ unsigned long slof_flash_addr;
+ /* SLOF is known to run on systems with following values
+* for the compatible property: */
+ char *compstrs[] = {IBM,Bimini, IBM,JS21, IBM,JS20,
IBM,CBEA };
+ int i;
+
+ for (i = 0; i ARRAY_SIZE(compstrs); i++) {
+ compatible = of_find_compatible_node(NULL, NULL,
compstrs[i]);
+
+ if (compatible)
+ break;
+ }
Can you identify slof from the information in the /openprom node? I
don't think all js20 and 21 use slof, although the IBM provided
firmware may also work with this driver.
+
+ /* not a system with a SLOF flash */
+ if (!compatible)
+ return -ENODEV;
+
+ of_node_put(compatible);
+
+ slof_flash = of_find_node_by_type(NULL, flash);
+ if (!slof_flash) {
+ printk(KERN_WARNING SLOF FLASH:
+ no flash node found in device-tree\n);
+ return -ENODEV;
+ }
+ rc = of_address_to_resource(slof_flash, 0, r);
+ if (rc) {
+ printk(KERN_WARNING SLOF FLASH:
+ failed to get address (err %d)\n, rc);
+ goto out;
+ }
+
+ slof_flash_addr = r.start;
+ slof_flash_len = r.end - r.start + 1;
+
+ if ((slof_flash_len = 0) || (!slof_flash_addr)) {
+ printk(KERN_WARNING SLOF FLASH: address or length is
0\n);
+ rc = -EIO;
+ goto out;
+ }
Why are these warnings? again, debug is more approprate
+
+ slof_flash_start = ioremap(slof_flash_addr, slof_flash_len);
+ if (!slof_flash_start) {
+ printk(KERN_WARNING SLOF FLASH: failed to ioremap\n);
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ printk(KERN_INFO SLOF FLASH: %luk at 0x%lx mapped to %p\n,
+ slof_flash_len 10, slof_flash_addr,
slof_flash_start);
This looks to be a debug message at most.
+
+ rc = misc_register(slof_flash_dev);
And as I said, this should be a mtd driver.
Thanks,
milton
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Re: [PATCH] powerpc: Add support to access the flash on SLOF based systems
On Sat, Jan 10, 2009 at 11:52:56AM -0600, Milton Miller wrote:
On Sun Jan 11 at 02:31:22 EST in 2009, Adrian Reber wrote:
This adds support for a simple character device to access the
flash for SLOF based systems like the PowerStation, QS2x and
PXCAB. In the SLOF git there is a user space program with
which the content of the flash for SLOF based systems can
be displayed and modified. This can be used to add a Linux
image to the flash and then directly boot the kernel from the
flash.
Signed-off-by: Adrian Reber adrian at lisas.de
---
This is based on the mmio NVRAM driver. I am not sure how useful this
is for anybody else but I am posting it anyway, hoping to get some
feedback. Also hoping it can be included at one point.
Normally such drivers are written and mtd drivers.
If slof were not an of implementation I would just say put the right
properties on the node in the device tree, but the kernel should adapt
to real OF. It should be easy to write a driver to hook up a mtd
platform device if this is a direct mapped flash.
The reason why I did not use mtd is that part of the flash is used by
the firmware image and I do not know if that works with mtd, if only a
part of the flash can be used. SLOF does also a CRC check over the
firmware image, so that image must have valid SLOF CRC. The flash is
a direct mapped flash, but the size of the firmware can vary.
+
+static void __iomem *slof_flash_start;
+static long slof_flash_len;
+static DEFINE_SPINLOCK(slof_flash_lock);
+
+
+static ssize_t slof_flash_read(struct file *file, char __user *buf,
+ size_t count, loff_t *ppos)
+{
+ unsigned long flags;
+ char *tmp;
+ int rc;
+
+ spin_lock_irqsave(slof_flash_lock, flags);
+
+ memcpy_fromio(tmp, slof_flash_start + *ppos, count);
+
+ spin_unlock_irqrestore(slof_flash_lock, flags);
+
Why do you need a spinlock? Why does it need to be irq safe?
I must confess I copied that code from the nvram driver and I do not
know if it is necessary.
This decision is also driving the malloc of the temporary buffer, and
you are intentionally returning a short read to userspace.
+
+const struct file_operations slof_flash_fops = {
+ .owner = THIS_MODULE,
+ .llseek = slof_flash_llseek,
+ .read = slof_flash_read,
+};
+
You mentioned userspace reflashing the image, but this driver seems to
be read only access.
This driver is read only. I am writing the new flash image using the
RTAS functionality to update the firmware flash. Using this device I can
use a userspace tool to add a file to the flash. The tool puts the
result on the local filesystem. Then using the normal RTAS flash update
it can be rewritten. That way I can add a kernel (with a ramdisk) to the
flash and then let SLOF boot that kernel. This is especially interesting
for the PXCAB Cell based PCI Express card.
+static struct miscdevice slof_flash_dev = {
+ SLOF_FLASH_MINOR,
+ slof_flash,
+ slof_flash_fops
+};
+
+
+static int __init slof_flash_init(void)
+{
+ struct device_node *slof_flash;
+ struct device_node *compatible;
+ struct resource r;
+ int rc;
+ unsigned long slof_flash_addr;
+ /* SLOF is known to run on systems with following values
+* for the compatible property: */
+ char *compstrs[] = {IBM,Bimini, IBM,JS21, IBM,JS20,
IBM,CBEA };
+ int i;
+
+ for (i = 0; i ARRAY_SIZE(compstrs); i++) {
+ compatible = of_find_compatible_node(NULL, NULL,
compstrs[i]);
+
+ if (compatible)
+ break;
+ }
Can you identify slof from the information in the /openprom node? I
Yes I can identify SLOF from the model property in the /openprom node. I
did not do it because there is almost no code accessing the /openprom
node and therefore I did not read it.
don't think all js20 and 21 use slof, although the IBM provided firmware
may also work with this driver.
There are probably only very few js20/js21 which are using SLOF. I do
not think the original IBM product firmware for those blades mentions
anything about js20/js21 in the compatible node. I do not have access to
such a system but the compatible node usually has some product number,
if I remember it correctly.
I am pretty sure that the original js20/js21 firmware does not have the
flash in the device tree, because RTAS is supposed to be the only valid
way to access the flash.
+
+ /* not a system with a SLOF flash */
+ if (!compatible)
+ return -ENODEV;
+
+ of_node_put(compatible);
+
+ slof_flash = of_find_node_by_type(NULL, flash);
+ if (!slof_flash) {
+ printk(KERN_WARNING SLOF FLASH:
+ no flash node found in device-tree\n);
+ return -ENODEV;
+ }
+ rc = of_address_to_resource(slof_flash, 0, r);
