From: Patrick Rudolph <[email protected]> Make all CBMEM buffers available to userland. This is useful for tools that are currently using /dev/mem.
Make the id, size and address available, as well as the raw table data. Tools can easily scan the right CBMEM buffer by reading /sys/bus/coreboot/drivers/cbmem/coreboot*/cbmem_attributes/id or /sys/bus/coreboot/devices/coreboot*/cbmem_attributes/id The binary table data can then be read from /sys/bus/coreboot/drivers/cbmem/coreboot*/cbmem_attributes/data or /sys/bus/coreboot/devices/coreboot*/cbmem_attributes/data Signed-off-by: Patrick Rudolph <[email protected]> --- -v2: - Add ABI documentation - Add 0x prefix on hex values -v3: - Use BIN_ATTR_RO -v4: - Use temporary memremap instead of persistent ioremap - Constify a struct - Get rid of unused headers - Use dev_{get|set}_drvdata - Use dev_groups to automatically handle attributes - Updated file description - Updated ABI documentation --- Documentation/ABI/stable/sysfs-bus-coreboot | 44 +++++++ drivers/firmware/google/Kconfig | 9 ++ drivers/firmware/google/Makefile | 1 + drivers/firmware/google/cbmem-coreboot.c | 128 ++++++++++++++++++++ drivers/firmware/google/coreboot_table.h | 14 +++ 5 files changed, 196 insertions(+) create mode 100644 Documentation/ABI/stable/sysfs-bus-coreboot create mode 100644 drivers/firmware/google/cbmem-coreboot.c diff --git a/Documentation/ABI/stable/sysfs-bus-coreboot b/Documentation/ABI/stable/sysfs-bus-coreboot new file mode 100644 index 000000000000..6055906f41f2 --- /dev/null +++ b/Documentation/ABI/stable/sysfs-bus-coreboot @@ -0,0 +1,44 @@ +What: /sys/bus/coreboot/devices/.../cbmem_attributes/id +Date: Apr 2020 +KernelVersion: 5.6 +Contact: Patrick Rudolph <[email protected]> +Description: + coreboot device directory can contain a file named + cbmem_attributes/id if the device corresponds to a CBMEM + buffer. + The file holds an ASCII representation of the CBMEM ID in hex + (e.g. 0xdeadbeef). + +What: /sys/bus/coreboot/devices/.../cbmem_attributes/size +Date: Apr 2020 +KernelVersion: 5.6 +Contact: Patrick Rudolph <[email protected]> +Description: + coreboot device directory can contain a file named + cbmem_attributes/size if the device corresponds to a CBMEM + buffer. + The file holds an representation as decimal number of the + CBMEM buffer size (e.g. 64). + +What: /sys/bus/coreboot/devices/.../cbmem_attributes/address +Date: Apr 2020 +KernelVersion: 5.6 +Contact: Patrick Rudolph <[email protected]> +Description: + coreboot device directory can contain a file named + cbmem_attributes/address if the device corresponds to a CBMEM + buffer. + The file holds an ASCII representation of the physical address + of the CBMEM buffer in hex (e.g. 0x000000008000d000) and should + be used for debugging only. + +What: /sys/bus/coreboot/devices/.../cbmem_attributes/data +Date: Apr 2020 +KernelVersion: 5.6 +Contact: Patrick Rudolph <[email protected]> +Description: + coreboot device directory can contain a file named + cbmem_attributes/data if the device corresponds to a CBMEM + buffer. + The file holds a read-only binary representation of the CBMEM + buffer. diff --git a/drivers/firmware/google/Kconfig b/drivers/firmware/google/Kconfig index a3a6ca659ffa..11a67c397ab3 100644 --- a/drivers/firmware/google/Kconfig +++ b/drivers/firmware/google/Kconfig @@ -58,6 +58,15 @@ config GOOGLE_FRAMEBUFFER_COREBOOT This option enables the kernel to search for a framebuffer in the coreboot table. If found, it is registered with simplefb. +config GOOGLE_CBMEM_COREBOOT + tristate "Coreboot CBMEM access" + depends on GOOGLE_COREBOOT_TABLE + help + This option exposes all available CBMEM buffers to userland. + The CBMEM id, size and address as well as the raw table data + are exported as sysfs attributes of the corresponding coreboot + table. + config GOOGLE_MEMCONSOLE_COREBOOT tristate "Firmware Memory Console" depends on GOOGLE_COREBOOT_TABLE diff --git a/drivers/firmware/google/Makefile b/drivers/firmware/google/Makefile index d17caded5d88..62053cd6d058 100644 --- a/drivers/firmware/google/Makefile +++ b/drivers/firmware/google/Makefile @@ -2,6 +2,7 @@ obj-$(CONFIG_GOOGLE_SMI) += gsmi.o obj-$(CONFIG_GOOGLE_COREBOOT_TABLE) += coreboot_table.o +obj-$(CONFIG_GOOGLE_CBMEM_COREBOOT) += cbmem-coreboot.o obj-$(CONFIG_GOOGLE_FRAMEBUFFER_COREBOOT) += framebuffer-coreboot.o obj-$(CONFIG_GOOGLE_MEMCONSOLE) += memconsole.o obj-$(CONFIG_GOOGLE_MEMCONSOLE_COREBOOT) += memconsole-coreboot.o diff --git a/drivers/firmware/google/cbmem-coreboot.c b/drivers/firmware/google/cbmem-coreboot.c new file mode 100644 index 000000000000..f76704a6eec7 --- /dev/null +++ b/drivers/firmware/google/cbmem-coreboot.c @@ -0,0 +1,128 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * cbmem-coreboot.c + * + * Exports CBMEM as attributes in sysfs. + * + * Copyright 2012-2013 David Herrmann <[email protected]> + * Copyright 2017 Google Inc. + * Copyright 2019 9elements Agency GmbH + */ + +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/string.h> +#include <linux/module.h> +#include <linux/io.h> + +#include "coreboot_table.h" + +#define CB_TAG_CBMEM_ENTRY 0x31 + +struct cb_priv { + struct lb_cbmem_entry entry; +}; + +static ssize_t id_show(struct device *dev, + struct device_attribute *attr, char *buffer) +{ + const struct cb_priv *priv = dev_get_drvdata(dev); + + return sprintf(buffer, "%#08x\n", priv->entry.id); +} + +static ssize_t size_show(struct device *dev, + struct device_attribute *attr, char *buffer) +{ + const struct cb_priv *priv = dev_get_drvdata(dev); + + return sprintf(buffer, "%u\n", priv->entry.entry_size); +} + +static ssize_t address_show(struct device *dev, + struct device_attribute *attr, char *buffer) +{ + const struct cb_priv *priv = dev_get_drvdata(dev); + + return sprintf(buffer, "%#016llx\n", priv->entry.address); +} + +static DEVICE_ATTR_RO(id); +static DEVICE_ATTR_RO(size); +static DEVICE_ATTR_RO(address); + +static struct attribute *cb_mem_attrs[] = { + &dev_attr_address.attr, + &dev_attr_id.attr, + &dev_attr_size.attr, + NULL +}; + +static ssize_t data_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, + char *buffer, loff_t offset, size_t count) +{ + const struct device *dev = kobj_to_dev(kobj); + const struct cb_priv *priv = dev_get_drvdata(dev); + void *ptr; + + /* CBMEM is always RAM with unknown caching attributes. */ + ptr = memremap(priv->entry.address, priv->entry.entry_size, + MEMREMAP_WB | MEMREMAP_WT); + if (!ptr) + return -ENOMEM; + + count = memory_read_from_buffer(buffer, count, &offset, ptr, + priv->entry.entry_size); + memunmap(ptr); + + return count; +} + +static BIN_ATTR_RO(data, 0); + +static struct bin_attribute *cb_mem_bin_attrs[] = { + &bin_attr_data, + NULL +}; + +static const struct attribute_group cb_mem_attr_group = { + .name = "cbmem_attributes", + .attrs = cb_mem_attrs, + .bin_attrs = cb_mem_bin_attrs, +}; + +static const struct attribute_group *attribute_groups[] = { + &cb_mem_attr_group, + NULL, +}; + +static int cbmem_probe(struct coreboot_device *cdev) +{ + struct device *dev = &cdev->dev; + struct cb_priv *priv; + + priv = devm_kmalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + memcpy(&priv->entry, &cdev->cbmem_entry, sizeof(priv->entry)); + + dev_set_drvdata(dev, priv); + + return 0; +} + +static struct coreboot_driver cbmem_driver = { + .probe = cbmem_probe, + .drv = { + .name = "cbmem", + .dev_groups = attribute_groups, + }, + .tag = CB_TAG_CBMEM_ENTRY, +}; + +module_coreboot_driver(cbmem_driver); + +MODULE_AUTHOR("9elements Agency GmbH"); +MODULE_LICENSE("GPL"); diff --git a/drivers/firmware/google/coreboot_table.h b/drivers/firmware/google/coreboot_table.h index 7b7b4a6eedda..fc20b8649882 100644 --- a/drivers/firmware/google/coreboot_table.h +++ b/drivers/firmware/google/coreboot_table.h @@ -59,6 +59,19 @@ struct lb_framebuffer { u8 reserved_mask_size; }; +/* + * There can be more than one of these records as there is one per cbmem entry. + * Describes a buffer in memory containing runtime data. + */ +struct lb_cbmem_entry { + u32 tag; + u32 size; + + u64 address; + u32 entry_size; + u32 id; +}; + /* A device, additionally with information from coreboot. */ struct coreboot_device { struct device dev; @@ -66,6 +79,7 @@ struct coreboot_device { struct coreboot_table_entry entry; struct lb_cbmem_ref cbmem_ref; struct lb_framebuffer framebuffer; + struct lb_cbmem_entry cbmem_entry; }; }; -- 2.24.1 _______________________________________________ coreboot mailing list -- [email protected] To unsubscribe send an email to [email protected]
