Messages in this thread | | | Date | Mon, 15 Jul 2013 23:41:07 -0700 | From | Greg KH <> | Subject | Re: [linux-sunxi] Re: [PATCH 1/2] Initial support for Allwinner's Security ID fuses |
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On Mon, Jul 15, 2013 at 11:16:19PM +0200, Oliver Schinagl wrote: > > With your latest patches for binary attributes and your blog post, I > thought that you want to create your binary attributes before the probe > function, to avoid the userspace race. To do that, we have two options, > create them in init (ugly?) or fill the .group member if available so it > gets automatically created from the register function.
Yes, the .group thing should be what is needed here.
> Well in my case, I'm using the module_platform_driver() macro which > expects the struct platform_driver. Platform_driver has a device_driver > member .driver where the .groups is located. Great, using that works and > we should have the sysfs entry race-free. However I don't know hot to > exchange data between that and the rest of my driver. > > Before I used to_platform_device(kobj_to_dev(kobj)) as passed via the > .read function to obtain a platform_device where i could use > platform_get_drvdata on. All was good, but that doesn't fly now and my > knowledge is a bit short as to why.
I don't understand, why not use the platform device that was passed to the binary attribute write function?
> The second method is finding some other shared structure given that we > get a platform_device in the probe function, yet I couldn't find > anything and this platform_device isn't the same as the one from the .read.
It should be, why isn't it?
> Of course using a global var bypasses this issue, but I'm sure it won't > pass review ;)
The platform device structure should have what you need, right?
> So using these new patches for binary attributes, how can I pass data > between my driver and the sysfs files using a platform_driver? Or are > other 'hacks' needed and using the .groups attribute from > platform_driver->device_driver->groups is really the wrong approach. > > I did ask around and still haven't figured it out so far, so I do > apologize if you feel I'm wasting your precious time.
How is the platform device not the same thing that was passed to your probe function?
> > Oliver
> /* > * Copyright (c) 2013 Oliver Schinagl > * http://www.linux-sunxi.org > * > * Oliver Schinagl <oliver@schinagl.nl> > * > * This program is free software; you can redistribute it and/or modify > * it under the terms of the GNU General Public License as published by > * the Free Software Foundation; either version 2 of the License, or > * (at your option) any later version. > * > * This program is distributed in the hope that 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. > * > * This driver exposes the Allwinner security ID, a 128 bit eeprom, in byte > * sized chunks. > */ > > #include <linux/compiler.h> > #include <linux/device.h> > #include <linux/err.h> > #include <linux/export.h> > #include <linux/fs.h> > #include <linux/init.h> > #include <linux/io.h> > #include <linux/kernel.h> > #include <linux/kobject.h> > #include <linux/module.h> > #include <linux/platform_device.h> > #include <linux/random.h> > #include <linux/sysfs.h> > #include <linux/types.h> > > #define DRV_NAME "sunxi-sid" > > /* There are 4 32-bit keys */ > #define SID_KEYS 4 > /* Each key is 4 bytes long */ > #define SID_SIZE (SID_KEYS * 4) > > /* We read the entire key, due to a 32 bit read alignment requirement. Since we > * want to return the requested byte, this resuls in somewhat slower code and > * uses 4 times more reads as needed but keeps code simpler. Since the SID is > * only very rarly probed, this is not really an issue. > */ > static u8 sunxi_sid_read_byte(const void __iomem *sid_reg_base, > const unsigned int offset) > { > u32 sid_key; > > if (offset >= SID_SIZE) > return 0; > > sid_key = ioread32be(sid_reg_base + round_down(offset, 4)); > sid_key >>= (offset % 4) * 8; > > return sid_key; /* Only return the last byte */ > } > > static ssize_t eeprom_read(struct file *fd, struct kobject *kobj, > struct bin_attribute *attr, char *buf, > loff_t pos, size_t size) > { > struct platform_device *pdev; > void __iomem *sid_reg_base; > int i; > > pdev = to_platform_device(kobj_to_dev(kobj)); > sid_reg_base = (void __iomem *)platform_get_drvdata(pdev);
Great, isn't that what you need?
> printk("0x%x, 0x%x 0x%x 0x%x\n", kobj, kobj_to_dev(kobj), pdev, sid_reg_base); > > if (pos < 0 || pos >= SID_SIZE) > return 0; > if (size > SID_SIZE - pos) > size = SID_SIZE - pos; > > for (i = 0; i < size; i++) > buf[i] = sunxi_sid_read_byte(sid_reg_base, pos + i); > > return i; > }
What are you missing in this function that you have in your probe function?
This driver looks fine, what is not working properly?
totally confused,
greg k-h
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