WWAN (fibocom L850-GL) works in USB mode, so turn off PCIe 6.
BUG=b:194861116
Signed-off-by: Malik_Hsu <malik_hsu@wistron.corp-partner.google.com>
Change-Id: Ie04a5bb2af9ce11f57339f460a7f880bfc14b688
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56649
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Sync the MemInfoHob.h with current FSP code.
BUG=b:190339677
TEST=dmidecode -t 17 can show the memory information.
Signed-off-by: Eric Lai <ericr_lai@compal.corp-partner.google.com>
Change-Id: I80d1252b1f12b164d4f6d3a01221507cdfbe4d08
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56682
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Amanda Hwang <amanda_hwang@compal.corp-partner.google.com>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-by: Maulik V Vaghela <maulik.v.vaghela@intel.com>
Realtek speaker amplifiers under auto mode operation have Absolute Max
Rating (AMR) at 1.98 V. Hence probe the firmware config for speaker
amplifier and program the VCCIOSEL accordingly.
BUG=b:194120188
TEST=Build and boot to OS in Storo. Ensure that the VCCIO selection is
configured as expected and probing the GPIO reads the configured
voltage.
Change-Id: Ibd3bc90bd0bbc9a35922b29e3d1e106321bc7a06
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56616
Reviewed-by: Evan Green <evgreen@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Latency Tolerance Reporting is yet another PCIe power management feature
which can have a bad influence on realtime performance. Disable this
feature for all PCIe root ports.
Change-Id: I38023e095ca55efd2178ad944f651fee1f1c34cd
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56595
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
L1 substates of a PCIe link are meant to save some power when the link
is not active but have the drawback that the PCIe latency is increased
as PLLs are switched on and off as needed.
In order to get a better realtime performance, disable all substates for
every PCIe root port.
Change-Id: Ic5bc8410709d0f0094810bc11a7723e88c30e397
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56594
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
This variant uses I210 MACPHYs so enable the I210 driver in order to set
the needed MAC addresses. In addition add the function to retrieve a
valid MAC address for the given MACPHY.
Change-Id: Id1d59349db1b86cfdd71bbe27577c0530e8f0b51
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56567
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
All the boards based on the mc_ehl baseboard have the NC-FPGA available.
Enable the appropriate driver on baseboard level.
Change-Id: I40b76a837b7ddb70ceba3135996b1c1080170c4d
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56566
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
All variants based on mc_ehl will use the Siemens HWILIB. Select the
Kconfig switch on baseboard level.
Change-Id: I940f84a4a7449487fe78c793f8dbb1c1b49fa54b
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56565
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Enable IBECC for mc_ehl1 to provide a memory failure protection.
Change-Id: If8f81d6bacb77dc38e231c1cedf22831de8a38a9
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56564
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
In favor of better realtime performance disable dynamic frequency
support in the System Agent for mc_ehl1.
Change-Id: I0e62bcf2e5efa97d89bf7192f1536747a02ad992
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56563
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Enable measured boot for all boards based on mc_ehl baseboard.
Change-Id: I3aff943305c024d1f25d2127e6f60495828da3eb
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56542
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
All the boards based on the mc_ehl baseboard have a TPM which is
connected to SPI but mapped into the address space of the x86 so that
it acts like a LPC attached TPM. Enable the TPM driver so that it will
be used. In addition add the needed entry in devicetree.
Change-Id: I301d0ed4a108bac45d95eced120e7ba280945d9c
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56541
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
All the mainboards based on mc_ehl use the external RTC RX6110SA.
Enable the driver in Kconfig for all boards based on mc_ehl. In
addition, as mc_ehl1 has the RTC attached to the SMBus, add the
devicetree entry on behalf of the SMBus device 00:1f.4 for this variant.
Change-Id: Ie1f45d0e6f9063c00253fe58a6268d40de91cf63
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56523
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-by: Paul Menzel <paulepanter@mailbox.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
The x86 thread code is all x86_32 specific. It needs to be updated to
work with 64 bit. For now just throw an error when compiling.
BUG=b:179699789
TEST=none
Suggested-by: Furquan Shaikh <furquan@google.com>
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: I96187ad84bdec40c6883748afa41e217bc389b79
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56571
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
LTE module L850-GL may encounter U3 wakeup race condition with the host.
Setting xHCI LFPS periodic sampling off time to 0ms so that the host would not
miss the device-initiated U3 wakeup thus avoid the race condition.
BUG=b:193898133
BRANCH=dedede
TEST=flash the image to the device. Run following command to check the bits[7:4] is 0x0:
iotools mmio_read32 "XHCI MMIO BAR + 0x80A4"
Signed-off-by: Tao Xia <xiatao5@huaqin.corp-partner.google.com>
Change-Id: Ic84dc83b749cf3c6029a06730096b64ef8cb8cd9
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56626
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
TEST=Refer to `cbmem -t` output below:
Without this code changes, timestamp ids 962 and 963 are listed as
`unknown`.
962:<unknown> 1,704,863 (157)
963:<unknown> 1,704,878 (14)
With this code changes, lists the timestamps along with the timestamp
strings.
962:calling FspMultiPhaseSiInit 1,704,863 (157)
963:returning from FspMultiPhaseSiInit 1,704,878 (14)
Change-Id: I528567e4cc630e15dffffd1c7684798fcdde4535
Signed-off-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56641
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Configure I2C high / low time in the device tree to ensure I2C
CLK runs accurately between 380 kHz and 400 kHz.
Audio codec:388.91 kHz
Touchpad:394.48 kHz
BUG=b:193864546
BRANCH=dedede
TEST=Build and check after tuning I2C clock is between 380 kHz and 400 kHz
Signed-off-by: Alex1 Kao <alex1_kao@pegatron.corp-partner.google.com>
Change-Id: Ia57c90ead44ceb0990878dc0566e595bae5a9099
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56383
Reviewed-by: Kirk Wang <kirk_wang@pegatron.corp-partner.google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
When looking for C compilers, xcompile uses the "" prefix to "gcc" and
"clang" as a last-resort option. This fails in environments where such
default names are blocked to prevent "unclean" builds - such as Chrome
OS.
Allow overriding this prefix using the GENERIC_COMPILER_PREFIX variable
that is hopefully both descriptive enough to suggest what it is for and
unusual enough to not trigger by chance.
Change-Id: I16239f66730f1dbcb7482f223cea4ee5957af10c
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56643
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Martin Roth <martinroth@google.com>
Add supported memory parts in mem_parts_used.txt, and generate
SPD id for these parts.
MT53E512M32D1NP-046 WT:B
MT53E1G32D2NP-046 WT:B
H54G46CYRBX267
H54G56CYRBX247
K4U6E3S4AB-MGCL
K4UBE3D4AB-MGCL
BUG=b:194766276 b:194686484 b:194765811
TEST=build
Signed-off-by: David Wu <david_wu@quanta.corp-partner.google.com>
Change-Id: Iba019c50224be8322865eee7baf81e3a574ff9a4
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56630
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
This change adds the following memory parts to LP4x global list and
generates SPDs using gen_spd.go for ADL:
1. H54G46CYRBX267
2. H54G56CYRBX247
3. K4U6E3S4AB-MGCL
4. K4UBE3D4AB-MGCL
BUG=b:194686484 b:194765811
TEST=build.
Signed-off-by: David Wu <david_wu@quanta.corp-partner.google.com>
Change-Id: If85088f843ab11cc531a3975b5cac3e36b573970
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56597
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Add Charger Performance Control table TCHG for DPTF setting.
BUG=b:194256990
BRANCH=firmware-volteer-13672.B
TEST=build test firmware and verified by thermal team.
Change-Id: I9dba3f0e75d07d8ee9656bd1ee8d6de2d3b8c152
Signed-off-by: Wayne3 Wang <Wayne3_Wang@pegatron.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56500
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Ariel Chang <ariel_chang@pegatron.corp-partner.google.com>
Reviewed-by: Paul F Yang <paul.f.yang@intel.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Reviewed-by: Wayne3 Wang <wayne3_wang@pegatron.corp-partner.google.com>
Updating from commit id 1e800ac83:
2021-03-01 22:59:54 +0000 - (docs: point md files in master to main/HEAD)
to commit id 4c21b57eb:
2021-07-19 11:36:07 +0000 - (pd: Fix missing polarity_rm_dts in some conditions)
This brings in 3145 new commits.
Change-Id: Iff2e9f766e750070d71644c2f9895ad10e8b1c9a
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56431
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Updating from commit id 96404aa27:
2021-05-13 18:27:27 +0200 - (Merge "build(hooks): update Commitizen to ^4.2.4" into integration)
to commit id 586aafa3a:
2021-07-19 05:36:18 +0200 - (Merge "errata: workaround for Neoverse V1 errata 1791573" into integration)
This brings in 207 new commits.
Change-Id: Iaf8af5ffaf377070ee1430ed7cfdc51001a1ba6b
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56416
Reviewed-by: Julius Werner <jwerner@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
According to the schematic diagram of proto, modify the clock of nvme
from the baseboard default to src0.
BUG=b:194487277
Signed-off-by: Malik_Hsu <malik_hsu@wistron.corp-partner.google.com>
Change-Id: I41be517b434513bca2332ec37e54f56910302bb7
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56584
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
This reverts commit 4c569b52f6. This has
introduced a regression in mainboards using JSL SoC such that it
overrides the soft straps for all the GPIOs. This in turn has led to
some of the peripherals not working.
BUG=None
TEST=Build and boot to OS in Storo. Ensure that the regressed
peripherals are working back again.
Change-Id: Ibfeed1075fe28051b926ddd7ca771693dc19dae8
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56613
Reviewed-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This reverts commit ce79ceec86. This has
introduced a regression in mainboards using JSL SoC such that it
overrides the soft straps for all the GPIOs. This in turn has led to
some of the peripherals not working.
Change-Id: Ifea5d4d0f474873f8bf4818ec1986e534f455216
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56615
Reviewed-by: Evan Green <evgreen@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Use bit-wise and logical operators instead of their equivalent methods.
Built roda/rw11 with `BUILD_TIMELESS=1` and coreboot.rom remains the
same.
Change-Id: I30807e14b2a9a8203a76d418f586423bcaec2a3a
Signed-off-by: Felix Singer <felix.singer@secunet.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56606
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
Use `FOOO[1337]` instead of `Index(FOOO, 1337)`.
Built roda/rw11 with `BUILD_TIMELESS=1` and coreboot.rom remains the
same.
Change-Id: I4f5d5cb8ce8c3ae37dc44ca87bd67596af9feee8
Signed-off-by: Felix Singer <felix.singer@secunet.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56604
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
The GPE offset of 16 is PCH specific.
Built roda/rw11 with `BUILD_TIMELESS=1` and coreboot.rom remains the
same.
Change-Id: I4ec38fc28d2436f84a090bb4ab38f20612cfd795
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56080
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Add wifi sar for magister.
Due to fw-config cannot distinguish between magolor and magister.
Using sku_id to decide to load magister custom wifi sar.
BUG=b:192290227
TEST=build and test on magolor/magister
Cq-Depend: chrome-internal:3986580
Signed-off-by: David Wu <david_wu@quanta.corp-partner.google.com>
Change-Id: I4510cc2ad42a11ec802ecd439b353f8e87d63868
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56334
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
This dev tree config controls the Vnn/Vcc1P05 bypass mode for Jasperlake.
BUG=b:191691430
BRANCH=dedede
TEST=Build fw and confirm FSP setting are set properly by log
Signed-off-by: Simon Yang <simon1.yang@intel.com>
Change-Id: I10bc203d3fed32ab65f325978426b7d0fca6f392
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55744
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jamie Chen <jamie.chen@intel.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
This patch adds device tree settings to control pcie modphy tuning
FSP UPDs. With this patch, the pcie modphy can be tuned per board.
BUG=b:192716633
BRANCH=NONE
TEST=build dedede variant coreboot with fw_debug enable and check if
these settings have been changed successfully on fsp debug log.
Change-Id: I80a91d45f9dd8ef218846e1284fdad309313e831
Signed-off-by: Jamie Chen <jamie.chen@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56336
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
LTE module L850-GL may encounter U3 wakeup race condition with the host.
Setting xHCI LFPS periodic sampling off time to 0ms so that the host would not
miss the device-initiated U3 wakeup thus avoid the race condition.
BUG=b:191426542
BRANCH=dedede
TEST=flash the image to the device. Run following command to check the bits[7:4] is 0x0:
iotools mmio_read32 "XHCI MMIO BAR + 0x80A4"
Signed-off-by: Tao Xia <xiatao5@huaqin.corp-partner.google.com>
Change-Id: I3be7adad49f87956a6764ad91fec6e76681b393f
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56518
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Chiasheng Lee <chiasheng.lee@intel.com>
This symbol is only used in generating a default fmap.
Change-Id: I8d92eba9978cdad5795b0f5755e1d75db7b3cb2d
Signed-off-by: Arthur Heymans <arthur@aheymans.xyz>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56592
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Frans Hendriks <fhendriks@eltan.com>
Enable the impedance tracking for channel 2 and channel 3.
The impedance tracking can compensate the settings of impedance
when the temperature changes.
Signed-off-by: Ryan Chuang <ryan.chuang@mediatek.corp-partner.google.com>
Change-Id: I047ab70bb59736a8ba8ae75ab15659900c784342
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56620
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Reviewed-by: Hung-Te Lin <hungte@chromium.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Since the specification isn't very clear on this, add a comment about
the optional raw data part of a acpi_generic_error_status block.
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I6df7d2f216fe0515e89d08c8ed01f06d19461429
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56611
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Since current AMD SoCs don't need some wait time between INIT and SIPI,
we can skip the 10ms wait there, which improves the boot time a bit.
before: CPU_CLUSTER: 0 init finished in 632 msecs
after: CPU_CLUSTER: 0 init finished in 619 msecs
mpinit still works on Mandolin and all CPU cores show up and are usable.
This also doesn't change the binary in a timeless build for boards/SoCs
that don't select X86_AMD_INIT_SIPI which I verified for lenovo/x230.
BUG=b:193885336
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I1e044776f45021742a88a5e369a74383c1baaab6
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56533
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
The biosram accessor support in soc/amd/common/block/acpimmio/biosram.c
is only used on Stoneyridge and the old amd/southbridge code and not on
Picasso or Cezanne. It also only builds as a 32 bit binary and breaks
when trying to build as a 64 bit binary, since the size of an uintptr_t
is different on those two. There is no support for using the 32 bit
binaryPI with a 64 bit coreboot while there is code to use a 32 bit FSP
with 64 bit coreboot, so not building this for FSP-based SoC support
moves us one step closer to be able to build coreboot as 64 bit binary
for Picasso and Cezanne.
Signed-off-by: Felix Held <felix-coreboot@felixheld.de>
Change-Id: I2d87ec2fa1b217eaf55d865e4390308812502e56
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56570
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Malik_Hsu