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RISC-V updates for v5.3-rc4

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A few minor RISC-V updates for v5.3-rc4:
 
 - Remove __udivdi3() from the 32-bit Linux port, converting the only
   upstream user to use do_div(), per Linux policy
 
 - Convert the RISC-V standard clocksource away from per-cpu data structures,
   since only one is used by Linux, even on a multi-CPU system
 
 - A set of DT binding updates that remove an obsolete text binding in
   favor of a YAML binding, fix a bogus compatible string in the schema
     (thus fixing a "make dtbs_check" warning), and clarifies the future
       values expected in one of the RISC-V CPU properties
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Merge tag 'riscv/for-v5.3-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux

Pull RISC-V updates from Paul Walmsley:
 "A few minor RISC-V updates for v5.3-rc4:

   - Remove __udivdi3() from the 32-bit Linux port, converting the only
     upstream user to use do_div(), per Linux policy

   - Convert the RISC-V standard clocksource away from per-cpu data
     structures, since only one is used by Linux, even on a multi-CPU
     system

   - A set of DT binding updates that remove an obsolete text binding in
     favor of a YAML binding, fix a bogus compatible string in the
     schema (thus fixing a "make dtbs_check" warning), and clarifies the
     future values expected in one of the RISC-V CPU properties"

* tag 'riscv/for-v5.3-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
  dt-bindings: riscv: fix the schema compatible string for the HiFive Unleashed board
  dt-bindings: riscv: remove obsolete cpus.txt
  RISC-V: Remove udivdi3
  riscv: delay: use do_div() instead of __udivdi3()
  dt-bindings: Update the riscv,isa string description
  RISC-V: Remove per cpu clocksource
This commit is contained in:
Linus Torvalds 2019-08-10 16:31:47 -07:00
commit 296d05cb0d
7 changed files with 24 additions and 202 deletions
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162
Documentation/devicetree/bindings/riscv/cpus.txt
View File

@ -1,162 +0,0 @@
===================
RISC-V CPU Bindings
===================
The device tree allows to describe the layout of CPUs in a system through
the "cpus" node, which in turn contains a number of subnodes (ie "cpu")
defining properties for every cpu.
Bindings for CPU nodes follow the Devicetree Specification, available from:
https://www.devicetree.org/specifications/
with updates for 32-bit and 64-bit RISC-V systems provided in this document.
===========
Terminology
===========
This document uses some terminology common to the RISC-V community that is not
widely used, the definitions of which are listed here:
* hart: A hardware execution context, which contains all the state mandated by
the RISC-V ISA: a PC and some registers. This terminology is designed to
disambiguate software's view of execution contexts from any particular
microarchitectural implementation strategy. For example, my Intel laptop is
described as having one socket with two cores, each of which has two hyper
threads. Therefore this system has four harts.
=====================================
cpus and cpu node bindings definition
=====================================
The RISC-V architecture, in accordance with the Devicetree Specification,
requires the cpus and cpu nodes to be present and contain the properties
described below.
- cpus node
Description: Container of cpu nodes
The node name must be "cpus".
A cpus node must define the following properties:
- #address-cells
Usage: required
Value type: <u32>
Definition: must be set to 1
- #size-cells
Usage: required
Value type: <u32>
Definition: must be set to 0
- cpu node
Description: Describes a hart context
PROPERTIES
- device_type
Usage: required
Value type: <string>
Definition: must be "cpu"
- reg
Usage: required
Value type: <u32>
Definition: The hart ID of this CPU node
- compatible:
Usage: required
Value type: <stringlist>
Definition: must contain "riscv", may contain one of
"sifive,rocket0"
- mmu-type:
Usage: optional
Value type: <string>
Definition: Specifies the CPU's MMU type. Possible values are
"riscv,sv32"
"riscv,sv39"
"riscv,sv48"
- riscv,isa:
Usage: required
Value type: <string>
Definition: Contains the RISC-V ISA string of this hart. These
ISA strings are defined by the RISC-V ISA manual.
Example: SiFive Freedom U540G Development Kit
---------------------------------------------
This system contains two harts: a hart marked as disabled that's used for
low-level system tasks and should be ignored by Linux, and a second hart that
Linux is allowed to run on.
cpus {
#address-cells = <1>;
#size-cells = <0>;
timebase-frequency = <1000000>;
cpu@0 {
clock-frequency = <1600000000>;
compatible = "sifive,rocket0", "riscv";
device_type = "cpu";
i-cache-block-size = <64>;
i-cache-sets = <128>;
i-cache-size = <16384>;
next-level-cache = <&L15 &L0>;
reg = <0>;
riscv,isa = "rv64imac";
status = "disabled";
L10: interrupt-controller {
#interrupt-cells = <1>;
compatible = "riscv,cpu-intc";
interrupt-controller;
};
};
cpu@1 {
clock-frequency = <1600000000>;
compatible = "sifive,rocket0", "riscv";
d-cache-block-size = <64>;
d-cache-sets = <64>;
d-cache-size = <32768>;
d-tlb-sets = <1>;
d-tlb-size = <32>;
device_type = "cpu";
i-cache-block-size = <64>;
i-cache-sets = <64>;
i-cache-size = <32768>;
i-tlb-sets = <1>;
i-tlb-size = <32>;
mmu-type = "riscv,sv39";
next-level-cache = <&L15 &L0>;
reg = <1>;
riscv,isa = "rv64imafdc";
status = "okay";
tlb-split;
L13: interrupt-controller {
#interrupt-cells = <1>;
compatible = "riscv,cpu-intc";
interrupt-controller;
};
};
};
Example: Spike ISA Simulator with 1 Hart
----------------------------------------
This device tree matches the Spike ISA golden model as run with `spike -p1`.
cpus {
cpu@0 {
device_type = "cpu";
reg = <0x00000000>;
status = "okay";
compatible = "riscv";
riscv,isa = "rv64imafdc";
mmu-type = "riscv,sv48";
clock-frequency = <0x3b9aca00>;
interrupt-controller {
#interrupt-cells = <0x00000001>;
interrupt-controller;
compatible = "riscv,cpu-intc";
}
}
}

16
Documentation/devicetree/bindings/riscv/cpus.yaml
View File

@ -10,6 +10,18 @@ maintainers:
- Paul Walmsley <paul.walmsley@sifive.com>
- Palmer Dabbelt <palmer@sifive.com>
description: |
This document uses some terminology common to the RISC-V community
that is not widely used, the definitions of which are listed here:
hart: A hardware execution context, which contains all the state
mandated by the RISC-V ISA: a PC and some registers. This
terminology is designed to disambiguate software's view of execution
contexts from any particular microarchitectural implementation
strategy. For example, an Intel laptop containing one socket with
two cores, each of which has two hyperthreads, could be described as
having four harts.
properties:
compatible:
items:
@ -50,6 +62,10 @@ properties:
User-Level ISA document, available from
https://riscv.org/specifications/
While the isa strings in ISA specification are case
insensitive, letters in the riscv,isa string must be all
lowercase to simplify parsing.
timebase-frequency:
type: integer
minimum: 1

2
Documentation/devicetree/bindings/riscv/sifive.yaml
View File

@ -19,7 +19,7 @@ properties:
compatible:
items:
- enum:
- sifive,freedom-unleashed-a00
- sifive,hifive-unleashed-a00
- const: sifive,fu540-c000
- const: sifive,fu540
...

2
arch/riscv/lib/Makefile
View File

@ -5,5 +5,3 @@ lib-y += memset.o
lib-y += uaccess.o
lib-$(CONFIG_64BIT) += tishift.o
lib-$(CONFIG_32BIT) += udivdi3.o

6
arch/riscv/lib/delay.c
View File

@ -81,9 +81,13 @@ EXPORT_SYMBOL(__delay);
void udelay(unsigned long usecs)
{
u64 ucycles = (u64)usecs * lpj_fine * UDELAY_MULT;
u64 n;
if (unlikely(usecs > MAX_UDELAY_US)) {
__delay((u64)usecs * riscv_timebase / 1000000ULL);
n = (u64)usecs * riscv_timebase;
do_div(n, 1000000);
__delay(n);
return;
}

32
arch/riscv/lib/udivdi3.S
View File

@ -1,32 +0,0 @@
/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright (C) 2016-2017 Free Software Foundation, Inc.
*/
#include <linux/linkage.h>
ENTRY(__udivdi3)
mv a2, a1
mv a1, a0
li a0, -1
beqz a2, .L5
li a3, 1
bgeu a2, a1, .L2
.L1:
blez a2, .L2
slli a2, a2, 1
slli a3, a3, 1
bgtu a1, a2, .L1
.L2:
li a0, 0
.L3:
bltu a1, a2, .L4
sub a1, a1, a2
or a0, a0, a3
.L4:
srli a3, a3, 1
srli a2, a2, 1
bnez a3, .L3
.L5:
ret
ENDPROC(__udivdi3)

6
drivers/clocksource/timer-riscv.c
View File

@ -55,7 +55,7 @@ static u64 riscv_sched_clock(void)
return get_cycles64();
}
static DEFINE_PER_CPU(struct clocksource, riscv_clocksource) = {
static struct clocksource riscv_clocksource = {
.name = "riscv_clocksource",
.rating = 300,
.mask = CLOCKSOURCE_MASK(64),
@ -92,7 +92,6 @@ void riscv_timer_interrupt(void)
static int __init riscv_timer_init_dt(struct device_node *n)
{
int cpuid, hartid, error;
struct clocksource *cs;
hartid = riscv_of_processor_hartid(n);
if (hartid < 0) {
@ -112,8 +111,7 @@ static int __init riscv_timer_init_dt(struct device_node *n)
pr_info("%s: Registering clocksource cpuid [%d] hartid [%d]\n",
__func__, cpuid, hartid);
cs = per_cpu_ptr(&riscv_clocksource, cpuid);
error = clocksource_register_hz(cs, riscv_timebase);
error = clocksource_register_hz(&riscv_clocksource, riscv_timebase);
if (error) {
pr_err("RISCV timer register failed [%d] for cpu = [%d]\n",
error, cpuid);