Messages in this thread | | | Date | Tue, 16 Jul 2013 23:02:22 +0200 | From | Oliver Schinagl <> | Subject | Re: [linux-sunxi] Re: [PATCH 1/2] Initial support for Allwinner's Security ID fuses |
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On 07/16/13 08:41, Greg KH wrote: > 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. That's what I thought (and used). > >> 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? Because the pointers don't match and I get a null pointer from platform_get_data > >> 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? I think that's a little above my grasp :p > >> 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? Should, but doesn't :( > >> 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? I don't know :( But i'll add the relevant sections with printk results below, which I should have done before, then again those printk's were not supposed to be in that e-mail to begin with ;)
So if I'm not seeing something stupidly obvious, feel free to shout at me :)
static ssize_t sid_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); printk("0x%p, 0x%p, 0x%p, 0x%p\n", kobj, kobj_to_dev(kobj), pdev, sid_reg_base);
0xef1e7c80, 0xef1e7c78, 0xef1e7c68, 0x (null)
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; }
static struct bin_attribute sid_bin_attr = { .attr = { .name = "eeprom", .mode = S_IRUGO, }, .size = SID_SIZE, .read = sid_read, };
static struct bin_attribute *sunxi_sid_attrs[] = { &sid_bin_attr, NULL, };
static const struct attribute_group sunxi_sid_group = { .bin_attrs = sunxi_sid_attrs, };
static const struct attribute_group *sunxi_sid_groups[] = { &sunxi_sid_group, NULL, };
static int __init sunxi_sid_probe(struct platform_device *pdev) { struct resource *res; void __iomem *sid_reg_base; u8 entropy[SID_SIZE]; unsigned int i;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0); sid_reg_base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(sid_reg_base)) return PTR_ERR(sid_reg_base); platform_set_drvdata(pdev, sid_reg_base);
for (i = 0; i < SID_SIZE; i++) entropy[i] = sunxi_sid_read_byte(sid_reg_base, i); add_device_randomness(entropy, SID_SIZE); dev_dbg(&pdev->dev, "%s loaded\n", DRV_NAME); printk("0x%p, 0x%p\n", pdev, sid_reg_base);
0xef02b000, 0xf1c23800
return 0; }
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