If CONFIG_SPL_OS_BOOT is enabled, boot OS if kernel image is found
in FIT structure.
Signed-off-by: York Sun <york.sun@nxp.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
SPL supports U-Boot image in FIT format which has data outside of
FIT structure. This adds support for embedded data for normal FIT
images.
Signed-off-by: York Sun <york.sun@nxp.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Add Kconfig option SPL_GZIP and SPL_ZLIB to enable gunzip support for
SPL boot, eg. falcon boot compressed kernel image.
Signed-off-by: York Sun <york.sun@nxp.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
The GPT timer was already initialised in board_init_f() as
it is needed in dram init. Do not repeat timer init in
board_init_r().
Signed-off-by: Anatolij Gustschin <agust@denx.de>
Acked-by: Stefano Babic <sbabic@denx.de>
Add USB serial download protocol support to SPL. If the SoC started
in recovery mode the SPL will immediately switch to SDP and wait for
further downloads/commands from the host side.
Signed-off-by: Stefan Agner <stefan.agner@toradex.com>
Reviewed-by: Stefano Babic <sbabic@denx.de>
Reviewed-by: Łukasz Majewski <lukma@denx.de>
The function blk_dread will return -ENOSYS on failure or on success the
number of blocks read, which must be the number asked to read (otherwise
it failed somewhere). Correct this check.
Signed-off-by: Tom Rini <trini@konsulko.com>
During the the conversion to $(SPL_TPL_), the SPL_ fragment was
left over for the NOR, XIP and YMODEM boot methods in SPL, making
these unselectable.
This commit fixes this by dropping the spurious 'SPL_' fragment
from each line.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reported-by: Bo Shen <voice.shen@gmail.com>
Fixes: f94e643 (spl: consistently use $(SPL_TPL_) to select features for SPL and TPL builds)
We are now using an env_ prefix for environment functions. Rename these
two functions for consistency. Also add function comments in common.h.
Quite a few places use getenv() in a condition context, provoking a
warning from checkpatch. These are fixed up in this patch also.
Suggested-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
We are now using an env_ prefix for environment functions. Rename setenv()
for consistency. Also add function comments in common.h.
Suggested-by: Wolfgang Denk <wd@denx.de>
Signed-off-by: Simon Glass <sjg@chromium.org>
To fully support DM timer in SPL and TPL, we need a few things cleaned
up and normalised:
- inclusion of the uclass and drivers should be an all-or-nothing
decision for each stage and under control of $(SPL_TPL_)TIMER
instead of having the two-level configuration with TIMER and
$(SPL_TPL_)TIMER_SUPPORT
- when $(SPL_TPL_)TIMER is enabled, the ARMv8 generic timer code can
not be compiled in
This normalises configuration to $(SPL_TPL_)TIMER and moves the config
options to drivers/timer/Kconfig (and cleans up the collateral damage
to some defconfigs that had SPL_TIMER_SUPPORT enabled).
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
We can finally drop TPL_STACK, TPL_TEXT_BASE and TPL_MAX_SIZE off the
whitelist (this time it's really happening!) and migrate the setting
(only used on the RK3368-uQ7 so far) into Kconfig.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Let's clean up behind ourselves and move the (newly defined)
TPL_STACK, TPL_MAX_SIZE and TPL_TEXT_BASE into Kconfig. Given that
0x0 might be considered to be valid values for TPL_TEXT_BASE and
TPL_STACK, we need to introduce helper config options
("TPL_NEEDS_SEPARATE_...") to indicate that these symbols are used
(and not inherited from their SPL variants) for any given
target-platform.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Now that we have split up SPL_LDSCRIPT into a SPL and TPL variant and
have started to use the TPL-variant for the RK3368, it's time to clean
up behind ourselves: move both variants into Kconfig and remove them
from the whitelist.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
This adds the TPL_DRIVER_MISC_SUPPORT option to allow activation of
DRIVER_MISC_SUPPORT for devices that need it in the TPL stage.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
To allow for a finer-grained control of features for TPL and SPL
builds all modules/boot-methods/etc. need to be consistently selected
based on the $(SPL_TPL_) macros.
This allows splitting the associated config-options in Kconfig: we
don't split the Kconfig options here and now, as this should happen on
an as-needed basis, whenever someone needs a feature/boot-method/etc.
in their TPL.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
As include/malloc.h already checks for SYS_MALLOC_SIMPLE using the
CONFIG_IS_ENABLED macro, we need to move to having separate entries
as we switch to fully separate configuration for SPL and TPL.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Even though there's now a TPL_DM configuration option, the spl logic
still checks for SPL_DM and thus does not pick up the proper config
option.
This introduces the use of CONFIG_IS_ENABLED(DM) in spl.c to always
pick up the desired configuration option instead of having a
hard-coded check for the SPL variant.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
TPL_NAND_SUPPORT, TPL_SERIAL_SUPPORT, TPL_SPI_FLASH_SUPPORT and
TPL_SPI_SUPPORT refer to SPL in their help text. This fixes up
the description to correctly reference TPL.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
The (upstream) changes to break up SYS_MALLOC_F_LEN for the full
U-Boot and the SPL stage, break TPL (if simple malloc is enabled in
TPL).
This adds support for a TPL-variant of SYS_MALLOC_F_LEN:
- adds TPL_SYS_MALLOC_F_LEN
- rewrites a test for CONFIG_SPL_SYS_MALLOC_F_LEN to access
CONFIG_VAL(SYS_MALLOC_F_LEN)
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
On the RK3368, we want our TPL to use the 'return to bootrom' boot
method (to have the bootrom load up the SPL stage) and then continue
with different boot methods (MMC, SPI, etc.) from SPL.
This adds the config option needed to control the availabily of the
'return to bootrom' boot-method separately for the TPL stage.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Some devices (e.g. the RK3368) have only limited SRAM, but provide
support for loading the next boot stage after our SPL performs basic
setup (e.g. DRAM).
For target systems like these, we add a boot device BOOTROM that will
invoke a board-specific hook to return to the bootrom (if supported).
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
At present if U-Boot proper uses driver model for MMC, then SPL has to
also. While this is desirable, it places a significant barrier to moving
to driver model in some cases. For example, with a space-constrained SPL
it may be necessary to enable CONFIG_SPL_OF_PLATDATA which involves
adjusting some drivers.
Add new SPL versions of the options for DM_MMC, DM_MMC_OPS and BLK. By
default these follow their non-SPL versions, but this can be changed by
boards which need it.
Signed-off-by: Simon Glass <sjg@chromium.org>
Some platforms have very limited SRAM to run SPL code, so there may
not be the same amount space for a malloc pool before relocation in
the SPL stage as the normal U-Boot stage.
Make SPL and (the full) U-Boot stage use independent SYS_MALLOC_F_LEN,
so the size of pre-relocation malloc pool can be configured memory
space independently.
Signed-off-by: Andy Yan <andy.yan@rock-chips.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
[fixed up commit-message:]
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
This function is only used in common/spl/spl_mmc.c[
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
The 'mode' parameter is actually a flag to determine whether to display
a list of devices found during the scan. Rename it to reflect this, add a
function comment and adjust callers to use a boolean.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Some of the functions within spl_fit will be used for non spl purposes.
Instead of duplicating functions simply break the functions to be reused
into its own file.
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Only add the new define to image.h, otherwise we see breakage
due to massive include leakage into host tools in some cases]
Signed-off-by: Tom Rini <trini@konsulko.com>
Fastmap was always enabled in ubispl, make it selectable by
CONFIG_MTD_UBI_FASTMAP.
Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Acked-by: Heiko Schocher <hs@denx.de>
Enable support for XIP (execute in place) of U-Boot or kernel image. There is
no need to copy image from flash to ram if flash supports execute in place.
Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
Reviewed-by: Alexandru Gagniuc <alex.g@adaptrum.com>
On ARM v7M, the processor will return to ARM mode when executing blx
instruction with bit 0 of the address == 0. Always set it to 1 to stay in thumb
mode.
At present, it is applied only for raw U-Boot. This patch moves it to just
before booting next image. This way armv7m will be in thumb mode for any image
like raw or image with header like zImage or standard U-Boot.
Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
Much of the entries here simply depend on SPL (or TPL). Instead of this
redundancy use if SPL / if TPL to guard the rest of the choices and only
show them when we have the relevant option enabled.
Signed-off-by: Tom Rini <trini@konsulko.com>
At present bootstage only supports U-Boot proper. But SPL can also consume
boot time so it is useful to have the record start there.
Add bootstage support to SPL. Also support stashing the timing information
when SPL finishes so that it can be picked up and reported by U-Boot
proper. This provides a full boot time record, excluding only the time
taken by the boot ROM.
Signed-off-by: Simon Glass <sjg@chromium.org>
Add Kconfig symbols for various configurations
supported by FAT filesystem support code.
CONFIG_SUPPORT_VFAT has been left out since its
force enabled in include/fat.h and probably
should get removed at some point.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
[trini: add select FS_FAT for CMD_FAT and SPL_FAT_SUPPORT]
Signed-off-by: Tom Rini <trini@konsulko.com>
Commit 94e3c8c4fd ("crypto/fsl - Add progressive hashing support
using hardware acceleration.") created entries for CONFIG_SHA1,
CONFIG_SHA256, CONFIG_SHA_HW_ACCEL, and CONFIG_SHA_PROG_HW_ACCEL.
However, no defconfig has migrated to it. Complete the move by first
adding additional logic to various Kconfig files to select this when
required and then use the moveconfig tool. In many cases we can select
these because they are required to implement other drivers. We also
correct how we include the various hashing algorithms in SPL.
This commit was generated as follows (after Kconfig additions):
[1] tools/moveconfig.py -y SHA1 SHA256 SHA_HW_ACCEL
[2] tools/moveconfig.py -y SHA_PROG_HW_ACCEL
Note:
We cannot move SHA_HW_ACCEL and SHA_PROG_HW_ACCEL simultaneously
because there is dependency between them.
Cc: Poonam Aggrwal <poonam.aggrwal@freescale.com>
Cc: Naveen Burmi <NaveenBurmi@freescale.com>
Cc: Po Liu <po.liu@freescale.com>
Cc: Shengzhou Liu <Shengzhou.Liu@freescale.com>
Cc: Priyanka Jain <Priyanka.Jain@freescale.com>
Cc: Shaohui Xie <Shaohui.Xie@freescale.com>
Cc: Chunhe Lan <Chunhe.Lan@freescale.com>
Cc: Chander Kashyap <k.chander@samsung.com>
Cc: Steve Rae <steve.rae@raedomain.com>
Cc: Dirk Eibach <eibach@gdsys.de>
Cc: Feng Li <feng.li_2@nxp.com>
Cc: Alison Wang <alison.wang@freescale.com>
Cc: Sumit Garg <sumit.garg@nxp.com>
Cc: Mingkai Hu <Mingkai.Hu@freescale.com>
Cc: York Sun <york.sun@nxp.com>
Cc: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
Cc: Jaehoon Chung <jh80.chung@samsung.com>
Cc: Akshay Saraswat <akshay.s@samsung.com>
Cc: Heiko Schocher <hs@denx.de>
Cc: Jagan Teki <jagan@amarulasolutions.com>
Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
This converts the following to Kconfig:
CONFIG_SPL_BOARD_INIT
Signed-off-by: Ley Foon Tan <ley.foon.tan@intel.com>
[trini: Update the Kconfig logic]
Signed-off-by: Tom Rini <trini@konsulko.com>
So far we were not using the FIT image format to its full potential:
The SPL FIT loader was just loading the first image from the /images
node plus one of the listed DTBs.
Now with the refactored loader code it's easy to load an arbitrary
number of images in addition to the two mentioned above.
As described in the FIT image source file format description, iterate
over all images listed at the "loadables" property in the configuration
node and load every image at its desired location.
This allows to load any kind of images:
- firmware images to execute before U-Boot proper (for instance
ARM Trusted Firmware (ATF))
- firmware images for management processors (SCP, arisc, ...)
- firmware images for devices like WiFi controllers
- bit files for FPGAs
- additional configuration data
- kernels and/or ramdisks
The actual usage of this feature would be platform and/or board specific.
Also update the FIT documentation to mention the new SPL feature and
provide an example .its file to demonstrate its features.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Lokesh Vutla <lokeshvuta@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
At the moment we load two images from a FIT image: the actual U-Boot
image and the .dtb file. Both times we have very similar code, that deals
with alignment requirements the media we load from imposes upon us.
Factor out this code into a new function, which we just call twice.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Jagan Teki <jagan@openedev.com>
At the moment we ignore any errors due to missing FIT properties,
instead go ahead and calculate our addresses with the -1 return value.
Fix this and bail out if any of the mandatory properties are missing.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Jagan Teki <jagan@openedev.com>
Currently the SPL FIT loader always looks only for the first image in
the /images node a FIT tree, which it loads and later executes.
Generalize this by looking for a "firmware" property in the matched
configuration subnode, or, if that does not exist, for the first string
in the "loadables" property. Then using the string in that property,
load the image of that name from the /images node.
This still loads only one image at the moment, but refactors the code to
allow extending this in a following patch.
To simplify later re-usage, we also generalize the spl_fit_select_index()
function to not return the image location, but just the node offset.
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Lokesh Vutla <lokeshvuta@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Jagan Teki <jagan@openedev.com>
Currently the SPL FIT loader uses the spl_fit_select_fdt() function to
find the offset to the right DTB within the FIT image.
For this it iterates over all subnodes of the /configuration node in
the FIT tree and compares all "description" strings therein using a
board specific matching function.
If that finds a match, it uses the string in the "fdt" property of that
subnode to locate the matching subnode in the /images node, which points
to the DTB data.
Now this works very well, but is quite specific to cover this particular
use case. To open up the door for a more generic usage, let's split this
function into:
1) a function that just returns the node offset for the matching
configuration node (spl_fit_find_config_node())
2) a function that returns the image data any given property in a given
configuration node points to, additionally using a given index into
a possbile list of strings (spl_fit_select_index())
This allows us to replace the specific function above by asking for the
image the _first string of the "fdt" property_ in the matching
configuration subnode points to.
This patch introduces no functional changes, it just refactors the code
to allow reusing it later.
(diff is overly clever here and produces a hard-to-read patch, so I
recommend to throw a look at the result instead).
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Lokesh Vutla <lokeshvuta@ti.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Jagan Teki <jagan@openedev.com>
ATF(ARM Trusted Firmware) is used by ARM arch64 SoCs, find more infomation
about ATF at: https://github.com/ARM-software/arm-trusted-firmware
SPL is considered as BL2 in ATF terminology, it needs to load other parts
of ATF binary like BL31, BL32, SCP-BL30, and BL33(U-Boot). And needs to
prepare the parameter for BL31 which including entry and image information
for all other images. Then the SPL handle PC to BL31 with the parameter,
the BL31 will do the rest of work and at last get into U-Boot(BL33).
This patch needs work with patches from Andre for SPL support multi
binary in FIT.
The entry point of bl31 and bl33 are still using hard code because we
still can not get them from the FIT image information.
Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
This simplifies makefiles. Also, arrange the order of objects in
drivers/mmc/Makefile so that the framework objects are listed before
drivers.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Now CONFIG_GENERIC_MMC and CONFIG_MMC match for all defconfig.
We do not need two options for the same feature. Deprecate the
former.
This commit was generated with the sed script 's/GENERIC_MMC/MMC/'
and manual fixup of drivers/mmc/Kconfig.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
The SPL-DFU feature enable to load and
execute u-boot from RAM over usb from
PC using dfu-util.
Hence dfu-reset should not be issued
when dfu-util -R switch is issued.
Signed-off-by: Ravi Babu <ravibabu@ti.com>
Since SPL_DFU_SUPPORT is depends on SPL_RAM_SUPPORT,
hence select SPL_DFU_SUPPORT only when
SPL_RAM_SUPPORT is chosen.
Signed-off-by: Ravi Babu <ravibabu@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
In single stage bootmode or falcon boot mode, the SPL shall update the
device tree that we load with the normal fixups done via
arch_fixup_fdt(), when possible (ie we have enough information in this
restricted environment to be able to do that still). This will include
for example updating them memory nodes.
Signed-off-by: Ravi Babu <ravibabu@ti.com>
[trini: Reword commit message]
Move the assignment of board info to global data a bit early which is
safe,
so that ram details can be used to enable caches.
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Ravi Babu <ravibabu@ti.com>
Reviewed-by: Lukasz Majewski <lukma@denx.de>
Reviewed-by: Tom Rini <trini@konsulko.com>
For the RK3399-Q7, we need some flexibility (depending on the feature
set we include in the SPL stage and how large our SPI flash is) in
positioning the SPL payload (i.e. the FIT image containing U-Boot, ATF
and the M0 payload) in our SPI flash.
To avoid having to deal with this through different U-Boot images, we
introduce a the '/config/u-boot,spl-payload-offset' property node
allow it to override the default setting.
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Acked-by: Simon Glass <sjg@chromium.org>
At present fdt blob or argument address being passed to kernel is fixed at
compile time using macro CONFIG_SYS_SPL_ARGS_ADDR. FDT blob from
different media like nand, nor flash are copied to the address pointed
by the macro.
The problem is, it makes args/fdt blob compulsory to copy which is not required
in cases like for NOR Flash. This patch removes this limitation.
Signed-off-by: Vikas Manocha <vikas.manocha@st.com>
FIT support in the net boot case is much like the RAM boot case in that
we load our image to "load_addr" and pass a dummy read function into
"spl_load_simple_fit()". As the load address is no longer hard-coded to
the final execution address, legacy image loading will require load_addr
to be set correctly in the image header.
Signed-off-by: Andrew F. Davis <afd@ti.com>
York Sun
Kever Yang
Anatolij Gustschin
Stefan Agner
Tom Rini
Philipp Tomsich
Simon Glass
Andy Yan
Masahiro Yamada
Cooper Jr., Franklin
Ladislav Michl
Vikas Manocha
Sekhar Nori
Ley Foon Tan
Andre Przywara
B, Ravi
Lokesh Vutla
Andrew F. Davis