On Tue, May 5, 2020 at 5:32 AM David E. Box <david.e....@linux.intel.com> wrote:
... > Register mappings are not provided by the driver. Instead, a GUID is read > from a header for each endpoint. The GUID identifies the device and is to > be used with an XML, provided by the vendor, to discover the available set > of metrics and their register mapping. This allows firmware updates to > modify the register space without needing to update the driver every time > with new mappings. Firmware writes a new GUID in this case to specify the > new mapping. Software tools with access to the associated XML file can > then interpret the changes. Is old hardware going to support this in the future? (I have in mind Apollo Lake / Broxton) > This module manages access to all PMT Telemetry endpoints on a system, > regardless of the device exporting them. It creates an intel_pmt_telem Name is not the best we can come up with. Would anyone else use PMT? Would it be vendor-agnostic ABI? (For example, I know that MIPI standardizes tracing protocols, like STM, do we have any plans to standardize this one?) telem -> telemetry. > class to manage the list. For each endpoint, sysfs files provide GUID and > size information as well as a pointer to the parent device the telemetry > comes from. Software may discover the association between endpoints and > devices by iterating through the list in sysfs, or by looking for the > existence of the class folder under the device of interest. A device node > of the same name allows software to then map the telemetry space for direct > access. ... > + tristate "Intel PMT telemetry driver" I think user should understand what is it from the title (hint: spell PMT fully). ... > obj-$(CONFIG_PMC_ATOM) += pmc_atom.o > +obj-$(CONFIG_INTEL_PMT_TELEM) += intel_pmt_telem.o Keep this and Kconfig section in order with the other stuff. ... bits.h? > +#include <linux/cdev.h> > +#include <linux/intel-dvsec.h> > +#include <linux/io-64-nonatomic-lo-hi.h> > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/pci.h> > +#include <linux/platform_device.h> > +#include <linux/slab.h> > +#include <linux/uaccess.h> > +#include <linux/xarray.h> ... > +/* platform device name to bind to driver */ > +#define TELEM_DRV_NAME "pmt_telemetry" Shouldn't be part of MFD header? ... > +#define TELEM_TBIR_MASK 0x7 GENMASK() ? > +struct pmt_telem_priv { > + struct device *dev; > + struct intel_dvsec_header *dvsec; > + struct telem_header header; > + unsigned long base_addr; > + void __iomem *disc_table; > + struct cdev cdev; > + dev_t devt; > + int devid; > +}; ... > + unsigned long phys = priv->base_addr; > + unsigned long pfn = PFN_DOWN(phys); > + unsigned long psize; > + > + psize = (PFN_UP(priv->base_addr + priv->header.size) - pfn) * > PAGE_SIZE; > + if (vsize > psize) { > + dev_err(priv->dev, "Requested mmap size is too large\n"); > + return -EINVAL; > + } ... > +static ssize_t guid_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + struct pmt_telem_priv *priv = dev_get_drvdata(dev); > + > + return sprintf(buf, "0x%x\n", priv->header.guid); > +} So, it's not a GUID but rather some custom number? Can we actually do a real GUID / UUID here? Because of TODO below I suppose it's not carved in stone (yet) and basically a protocol defined by firmware (which can be amended). ... > + /* TODO: replace with device properties??? */ So, please, fulfill. swnode I guess is what you are looking for. > + priv->dvsec = dev_get_platdata(&pdev->dev); > + if (!priv->dvsec) { > + dev_err(&pdev->dev, "Platform data not found\n"); > + return -ENODEV; > + } ... > + /* Local access and BARID only for now */ > + switch (priv->header.access_type) { > + case TELEM_ACCESS_LOCAL: > + if (priv->header.tbir) { > + dev_err(&pdev->dev, > + "Unsupported BAR index %d for access type > %d\n", > + priv->header.tbir, priv->header.access_type); > + return -EINVAL; > + } > + fallthrough; What's the point? > + > + case TELEM_ACCESS_BARID: > + break; > + default: > + dev_err(&pdev->dev, "Unsupported access type %d\n", > + priv->header.access_type); > + return -EINVAL; > + } > + err = alloc_chrdev_region(&priv->devt, 0, 1, TELEM_DRV_NAME); err or ret? Be consistent in the module. > + if (err < 0) { ' < 0' Do we need it? > + dev_err(&pdev->dev, > + "PMT telemetry chrdev_region err: %d\n", err); > + return err; > + } ... > + err = pmt_telem_create_dev(priv); > + if (err < 0) ' < 0' Do we need it? > + goto fail_create_dev; > + > + return 0; > +} ... > +static const struct platform_device_id pmt_telem_table[] = { > + { > + .name = "pmt_telemetry", > + }, { > + /* sentinel */ > + } { .name = ... }, {} is enough. > +}; ... > +static int __init pmt_telem_init(void) > +{ > + int ret = class_register(&pmt_telem_class); > + > + if (ret) int ret; ret = ... if (ret) > + return ret; > + > + ret = platform_driver_register(&pmt_telem_driver); > + if (ret) > + class_unregister(&pmt_telem_class); > + > + return ret; > +} ... > +{ > +} > + Extra blank line. > +module_init(pmt_telem_init); > +module_exit(pmt_telem_exit); Better to attach to the respective functions. ... > +#include <linux/intel-dvsec.h> There is no user of this below, but types.h has users here. > +/* Telemetry types */ > +#define PMT_TELEM_TELEMETRY 0 > +#define PMT_TELEM_CRASHLOG 1 > + > +struct telem_header { > + u8 access_type; If it's part of hardware communication, shouldn't be rather __uXX types to show that this is part of protocol between software and hardware? > + u8 telem_type; > + u16 size; > + u32 guid; > + u32 base_offset; > + u8 tbir; > +}; -- With Best Regards, Andy Shevchenko