Commit Graph

900 Commits

Author SHA1 Message Date
Samuel Holland
78c2b19218 lib: utils/irqchip: Automatically delegate T-HEAD PLIC access
The T-HEAD PLIC implementation requires setting a delegation bit
to allow access from S-mode. Now that the T-HEAD PLIC has its own
compatible string, set this bit automatically from the PLIC driver,
instead of reaching into the PLIC's MMIO space from another driver.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-10-21 10:06:00 +05:30
Wei Fu
422eda499c Makefile: Add build time and compiler info string
When we are doing opensbi development, we want to know the build time
and compiler info for debug purpose.

To enable this message, please add "BUILD_INFO=y", like:

```
make BUILD_INFO=y
```

NOTE: Using `BUILD_INFO=y` without specifying SOURCE_DATE_EPOCH will
violate "reproducible builds". So it's ONLY for development and debug
purpose, and should NOT be used in a product which follows "reproducible
builds".

Signed-off-by: Wei Fu <wefu@redhat.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
2021-10-20 15:10:52 +05:30
Heinrich Schuchardt
67cbbcb100 lib: sbi: system reset with invalid parameters
The SBI specification requires that sbi_system_reset() returns
SBI_ERR_INVALID_PARAM if reset_type or reset_reason are not valid.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Xiang W <wxjstz@126.com>
2021-10-18 16:07:21 +05:30
Anup Patel
c38973e087 lib: sbi: Save context for all non-retentive suspend types
Instead of saving context only for default non-retentive suspend,
we should save context for all non-retentive suspend types.

Fixes: 74756891cc ("lib: sbi: Implement SBI HSM suspend function")
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Xiang W <wxjstz@126.com>
2021-10-18 16:07:16 +05:30
Nikita Shubin
9283d503bd lib: sbi: add priority for reset handler
Let's make system_reset_check returning priority instead of only
true/false. In that case 0 - means not supported, and anything above
means priority that makes existing reset handlers being used in first
place, unless it is decided to lower their priority.

The handler with the most priority wins.

Signed-off-by: Nikita Shubin <n.shubin@yadro.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-10-11 10:32:26 +05:30
Nikita Shubin
516161c46f lib: sbi: convert reset to list
To support different handlers for different types of resets, we are
adding a sbi_list of restart handlers.

Instead of sbi_system_reset_set_device we use
sbi_system_reset_add_device to reflect the actual meaning.

Signed-off-by: Nikita Shubin <n.shubin@yadro.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-10-11 09:59:29 +05:30
Heinrich Schuchardt
754d51192b lib: utils: identify supported GPIO reset methods
The GPIO reset driver supports reset and poweroff. But not all boards
support both. gpio_system_reset_check() must detect this situation.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-10-01 10:24:43 +05:30
Anup Patel
fa59dd317a lib: utils/reset: use sbi_timer_mdelay() in gpio reset driver
We should use sbi_timer_mdelay() instead of custom gpio_mdelay() in
the gpio reset driver.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Xiang W <wxjstz@126.com>
2021-09-26 19:52:18 +05:30
Anup Patel
9d0ab35ab4 lib: sbi: Add generic timer delay loop function
We now have frequency of the timer device provided by the platform
support so we can emulate desired delay using a loop where the number
loop iterations are based on timer frequency.

This patch provides sbi_timer_delay_loop() for above purpose.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Xiang W <wxjstz@126.com>
2021-09-26 19:52:15 +05:30
Anup Patel
6355155f51 lib: sbi: Print timer frequency at boot time
We now have frequency in timer device instance provided by platform
so let's print timer frequency as part of the boot prints.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Xiang W <wxjstz@126.com>
2021-09-26 19:52:12 +05:30
Anup Patel
12e7af9ab7 lib: sbi: Add timer frequency to struct sbi_timer_device
Generic mdelay() and udelay() functions can be provided by the
sbi_timer framework if timer frequency is available in the timer
instance provided by the platform support or timer driver.

This patch adds timer frequency (timer_freq) member in the
struct sbi_timer_device for above purpose.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Xiang W <wxjstz@126.com>
2021-09-26 19:52:10 +05:30
Anup Patel
72154f4708 lib: utils/fdt: Add fdt_parse_timebase_frequency() function
We add fdt_parse_timebase_frequency() function which can be used
by ACLINT mtimer driver and platform code to get timebase frequency.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Xiang W <wxjstz@126.com>
2021-09-26 19:52:07 +05:30
Xiang W
51113fe2a5 lib: sbi: Add BUG() macro for csr_read/write_num() and misa_string()
We use BUG() macro in csr_read_num(), csr_write_num(), and
misa_string() functions for unhandled cases.

Signed-off-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-09-22 13:38:39 +05:30
Xiang W
12753d2256 lib: sbi: add some macros to detect BUG at runtime
Three macros are added. One is called BUG, which is used to put in an
unreachable branch. One is called BUG_ON, which is used to check bugs
and assert conditions are opposite. One is called SBI_ASSERT, used for
assertion checking.

Signed-off-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-09-22 13:35:30 +05:30
Xiang W
3477f08b08 lib: sbi: fix ctz bug
The original version of ctz will cause an endless loop, if the parameter
passed in is 0. This commit fixes this bug.

Signed-off-by: Xiang W <wxjstz@126.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-09-22 13:26:23 +05:30
Samuel Holland
395ff7eede lib: utils/reset: Add a sunxi watchdog reset driver
One of the watchdogs in the D1 SoC provides a "soft reset" function,
which allows software to immediately reset the entire SoC. Add a driver
so it can implement the SBI system reset function.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-09-14 13:24:53 +05:30
Samuel Holland
0274a96004 lib: utils/reset: Sort fdt_reset driver list
In preparation for adding a new fdt_reset driver, ensure the existing
lists are sorted alphabetically.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-09-14 12:13:55 +05:30
Dong Du
bd355213bf lib: sbi: Refine the way to construct platform features
sbi_platform_get_features_str() uses sbi_snprintf() to construct the
features_str. However, it passes the wrong length value (i.e., the nfstr),
which should be (nfstr-offset) as the starting point of str (i.e.,
features_str + offset) changes.

This commit also checks the return value of snprintf, and handles the
corner case that the string buffer is full.

Signed-off-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-09-03 12:16:01 +05:30
Dong Du
1718b1642e lib: sbi: Checking fifo validness in sbi_fifo_is_empty and is_full
As other exported fifo functions, we should check whether the fifo is
valid in sbi_fifo_is_empty and sbi_fifo_is_full. To this end, this patch
changes the retval from bool to int, and the two functions will return
SBI_EINVAL in the case the fifo is invalid.

Signed-off-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-09-03 11:59:35 +05:30
Dong Du
c262306533 lib: sbi: protect dprintf output with spinlock
Avoid getting messages from multiple harts (using dprintf and printf)
concurrently with a spinlock serializaing calls to sbi_dprintf(),
sbi_printf() and sbi_puts()

Signed-off-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-08-30 09:12:37 +05:30
Rahul Pathak
bd316e2c9b lib: sbi: Correct typo in faults delegation CSR name
Correcting the name of faults delegation CSR
%s/mfdeleg/medeleg

Signed-off-by: Rahul Pathak <rpathak@ventanamicro.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-08-30 09:07:47 +05:30
Samuel Holland
b1d3e91e9a payloads/test: Add support for SBI v0.2 ecalls
It can be useful to make SBI v0.2 or newer ecalls from this payload
for testing purposes. To support this, convert the macros to use the
extension/function parameter convention.

Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-08-20 09:48:45 +05:30
Samuel Holland
ee274377b2 lib: sbi_trap: Restore redirect for access faults
commit 764a17d852 ("lib: sbi: Implement firmware counters") added
switch cases for CAUSE_LOAD_ACCESS and CAUSE_STORE_ACCESS. This caused
them to stop being redirected to U or S mode, as that is handled in the
default switch case. As a result, an error in userspace could cause the
system to hang. Fix this by allowing the acces fault case to fall
through to the default case.

Fixes: 764a17d852 ("lib: sbi: Implement firmware counters")
Signed-off-by: Samuel Holland <samuel@sholland.org>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
2021-08-20 09:47:40 +05:30
Dong Du
33eac764f2 lib: sbi: Fix bug in sbi_ecall_rfence that misses checking
In sbi_ecall_rfence_handler, it will compare the funcid with
REMOTE_HFENCE_GVMA and REMOTE_HFENCE_VVMA_ASID. Later it check
whether the misa includes H-extension. This checking is incomplete
which misses REMOTE_HFENCE_GVMA_VMID and REMOTE_HFENCE_VVMA.

Fix the issue by updating the checking range.

Signed-off-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-08-20 09:42:39 +05:30
Anup Patel
7aa6c9aa96 lib: utils/timer: Simplify MTIMER synchronization
We simplify MTIMER synchronization as follows:

1) Detect MTIMER devices with unique (or non-shared) MTIME
   register at boot-time
2) Select first MTIMER device with no associated HART as our
   reference MTIMER device
3) Only synchronize MTIMER devices with unique (or non-shared)
   MTIME register using reference MTIMER device
4) Directly update the MTIME register at time of synchronization
   because MTIME is a read/write register.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-08-14 09:07:42 +05:30
Anup Patel
b35f7826b0 lib: utils/timer: Allow ACLINT MTIMER supporting only 32-bit MMIO
We can have ACLINT MTIMER devices which only support 32-bit MMIO
accesses on RV64 system so this patch adds a boolean DT property
"mtimer,no-64bit-mmio" to detect this from MTIMER DT node.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-08-14 09:02:44 +05:30
Anup Patel
f3a0eb8583 lib: utils/fdt: Extend fdt_parse_aclint_node() function
The fdt_parse_aclint_node() is used to parse DT node for SiFive
CLINT, ACLINT MTIMER, and ACLINT MSWI devices.

The ACLINT MTIMER has undergone following changes:
1) MTIMER DT node now requires separate addresses in for MTIME
   register and MTIMECMPx registers in the reg DT property.
2) MTIMER DT node might have no interrupts-extended DT property
   when the MTIMER device has no associated HARTs (i.e. the
   MTIMER device has no MTIMECMPx registers)

This patch extends fdt_parse_aclint_node() to handle above
mentioned changes in ACLINT MTIMER DT bindings.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-08-14 09:02:39 +05:30
Anup Patel
7a3a0cce4d lib: utils: Extend fdt_get_node_addr_size() for multiple register sets
We add "index" parameter to fdt_get_node_addr_size() API so that
calling function can specify index of desired register set. This
will allow fdt_get_node_addr_size() to handle DT nodes with
multiple register sets.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-08-14 09:02:36 +05:30
Anup Patel
e0d1b9db8a lib: utils/timer: Allow separate base addresses for MTIME and MTIMECMP
We extend the ACLINT library to support separate base addresses
for MTIME and MTIMECMP registers.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-08-14 09:02:33 +05:30
Bin Meng
47a47654e8 lib: utils/fdt: Change addr and size to uint64_t
The maximum address and size encoded in DT are 64-bit numbers, so we
should use uint64_t for 'addr' and 'size' in fdt_get_node_addr_size().

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-08-07 17:26:51 +05:30
Dong Du
d244f3dbd6 lib: sbi: Fix bug in strncmp function when count is 0
No need to compare characters when the count turns to 0.
Fix the issue in sbi_strncmp.

Signed-off-by: Dong Du <Dd_nirvana@sjtu.edu.cn>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-08-07 15:40:40 +05:30
Heinrich Schuchardt
e928472e67 lib: utils: support both of gpio-poweroff, gpio-reset
The generic GPIO reset driver has two entries in the match table:
"gpio-poweroff", "gpio-reset". Only the first entry is considered by
fdt_reset_init().

Define "gpio-poweroff" and "gpio-reset" as compatibility strings of two
separate reset drivers. They still can share code.

Fixes: e3d6919d10 ("lib: utils/reset: Add generic GPIO reset driver")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-07-27 17:26:54 +05:30
Heinrich Schuchardt
ce03c88ee1 lib: utils: remove unused variable in fdt_reset_init
The value of variable current_driver is unused. Remove the variable.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-07-27 17:16:02 +05:30
David Abdurachmanov
217d5e4880 generic: fu740: add workaround for CIP-1200 errata
Instruction TLB can fail to respect a non-global SFENCE thus we need to
flush the TLB using SFENCE.VMA x0, x0

See full description of CIP-1200 in Errata_FU740-C000_20210205 from
https://www.sifive.com/boards/hifive-unmatched

Signed-off-by: David Abdurachmanov <david.abdurachmanov@sifive.com>
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
2021-07-27 15:29:59 +05:30
Xiang W
74db0acbe5 firmware: use _fw_start for load address
The previous code uses _start as the load address, this default .entry is
the first segment, using _fw_start does not need to make this assumption.

Signed-off-by: Xiang W <wxjstz@126.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-27 15:20:49 +05:30
Bin Meng
989039117f Makefile: Manually forward RELAX_FLAG to the assembler when linking with LLD
When generating code with -mno-relax, GCC puts .option norelax in
the generated assembly, and so doesn’t bother passing on -mno-relax
to the assembler. This has the unfortunate effect that, when using
GCC to assemble hand-written assembly, -mno-relax does nothing,
and we have to pass -Wa,-mno-relax to manually forward it to the
assembler.

This is an old GCC bug that was fixed [1] recently. For the time
being, let's pass "-Wa,-mno-relax" to ASFLAGS for the GCC + LLD
combination to work, e.g.:

  $ make CC=riscv64-unknown-elf-gcc LLVM=1 PLATFORM=generic

[1] 3b0a7d624e

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-27 14:29:31 +05:30
Bin Meng
81eb7088b6 README: Update toolchain information
Recent FW_PIC=y changes actually require toolchains with PIE support
and it is on by default. Existing doc uses a GNU bare-metal toolchain
as examples but it does not support PIE.

Replace references of bare-metal toolchain prefix with Linux toolchain
prefix everywhere in documentation.

Also indicate that "riscv64-unknown-freebsd-" as an alternative to
"riscv64-linux-" GNU toolchain.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-17 18:32:20 +05:30
Bin Meng
2c74dc3c47 docs: Document FW_PIC compile time option
FW_PIC=y is on by default, but the doc is missing when this was
introduced. Add some description for it.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-17 17:43:37 +05:30
Bin Meng
a4555e5698 docs: Document parameters passed to firmware and alignment requirement
This updates documentation to describe parameters passed to firmware
from previous booting stage, and corresponding address alignment
requirement.

This also fixes a typo in fw_dynamic.md (it's => its).

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-17 17:30:48 +05:30
Bin Meng
8a1475b5a1 firmware: Remove the unhelpful alignment codes before fdt relocation
If the device tree is at an address that is not __SIZEOF_POINTER__
aligned, the fdt relocation code tries to align both source and
destination address to __SIZEOF_POINTER__ before the memory copy.
But such alignment can lead to unexpected results if either source
or destination address is not aligned.

In fact libfdt requires that the device tree must be at an 8-byte
aligned address. Hence remove the unhelpful alignment codes.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-17 17:13:43 +05:30
Alex Richardson
f3a8f603a7 include: types: Use __builtin_offsetof when supported
Clang provides a __builtin_offsetof which can be detected using
__has_builtin().

Signed-off-by: Alex Richardson <Alexander.Richardson@cl.cam.ac.uk>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-17 16:40:07 +05:30
Alex Richardson
7210e90785 firmware: use __SIZEOF_LONG__ for field offsets in fw_dynamic.h
The fields are of type unsigned long and are not pointers. While this
happens to be the same for RV32/RV64, it is not correct when compiling
for a CHERI-RISC-V system where pointers are twice the size of long.

Signed-off-by: Alex Richardson <Alexander.Richardson@cl.cam.ac.uk>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-17 16:35:23 +05:30
Green Wan
e3d6919d10 lib: utils/reset: Add generic GPIO reset driver
We add generic GPIO reset driver inspired from gpio-restart
and gpio-poweroff drivers of Linux kernel.

Signed-off-by: Green Wan <green.wan@sifive.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-07-17 14:12:07 +05:30
Green Wan
4c3df2ab96 lib: utils/gpio: Add minimal SiFive GPIO driver
We add a minimal SiFive GPIO driver so that we can do GPIO based
system power-off and reset.

Signed-off-by: Green Wan <green.wan@sifive.com>
Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-07-17 13:56:42 +05:30
Anup Patel
c14f1fe0df lib: utils/gpio: Add simple FDT based GPIO framework
We add a simple FDT based GPIO framework which is built on top
of generic GPIO library. The phandle of FDT GPIO chip DT node
is treated as unique GPIO chip ID required by the generic GPIO
library. The FDT based GPIO chip drivers will be probed on-demand
from fdt_gpio_pin_get() called by the GPIO client drivers.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-07-17 13:41:17 +05:30
Anup Patel
36b8effe4a lib: utils/gpio: Add generic GPIO configuration library
We add generic GPIO configuration library which is independent of
hardware description format (FDT or ACPI). The OpenSBI platform
support or GPIO drivers can register GPIO chip instances which
can be discovered and used by different GPIO clients. Each GPIO
chip instance has a unique ID which can be used by GPIO clients
to lookup GPIO chip instance.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-07-17 11:42:51 +05:30
Anup Patel
e931f387b2 lib: utils/fdt: Add fdt_parse_phandle_with_args() API
The libfdt project does not have a generic API to parse phandle
with args from a DT node so we add fdt_parse_phandle_with_args()
for this purpose. This new API will be useful to FDT based drivers.

Signed-off-by: Anup Patel <anup.patel@wdc.com>
Reviewed-by: Atish Patra <atish.patra@wdc.com>
2021-07-17 11:40:49 +05:30
Jessica Clarke
17729d44da lib: utils: Drop dependency on libgcc by importing part of FreeBSD's libquad
We only need libgcc for 64-bit division on RV32. Whilst GCC toolchains
bundle libgcc, Clang toolchains tend not to ship libclang_rt.builtins
given every compiler is a cross-compiler for every target and so you
would need a silly number of builds of it, with only the native library
available; only vendor-provided Clang toolchains specifically for bare
metal cross-compiling are likely to provide it.

Thus, import part of FreeBSD's implementation of the division support
functions needed and stop linking against libgcc.

Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Tested-by: Anup Patel <anup.patel@wdc.com>
2021-07-11 21:01:44 +05:30
Jessica Clarke
2942777425 Makefile: Support building with Clang and LLVM binutils
This is intended to mirror the Linux kernel. Building with CC=clang will
use Clang as the compiler but default to using the existing binutils.
Building with LLVM=1 will default to using Clang and LLVM binutils.

Whilst GCC will accept the -N linker option and forward it on to the
linker, Clang will not, and so in order to support both compilers we
must use -Wl, to forward it to the linker as is required for most other
linker options.

Note that there is currently a bug when using Clang as the compiler and
riscv64-linux-gnu-ld as the linker for FW_PIC=y. At first glance this
appears to be a bug in GNU binutils, but this could also be Clang or
OpenSBI at fault in some subtle way. Thus, for now, advise that this
combination be avoided.

Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
Tested-by: Anup Patel <anup.patel@wdc.com>
2021-07-11 20:22:55 +05:30
Jessica Clarke
09ad811ec4 firmware: Only default FW_PIC to y if supported
Bare-metal GNU ld does not support PIE, so if using it this will result
in a failure to build. Instead, default to FW_PIC=n if not supported.
Note that an explicit FW_PIC=y is not overridden, to ensure the build
fails rather than silently producing a position-dependent binary.

Signed-off-by: Jessica Clarke <jrtc27@jrtc27.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Anup Patel <anup.patel@wdc.com>
2021-07-11 20:03:06 +05:30