Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * arch/arm64/include/asm/arch_timer.h
3 *
4 * Copyright (C) 2012 ARM Ltd.
5 * Author: Marc Zyngier <marc.zyngier@arm.com>
6 *
7 * This program is free software: you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
18 */
19#ifndef __ASM_ARCH_TIMER_H
20#define __ASM_ARCH_TIMER_H
21
22#include <asm/barrier.h>
23#include <asm/sysreg.h>
24
25#include <linux/bug.h>
26#include <linux/init.h>
27#include <linux/jump_label.h>
28#include <linux/types.h>
29
30#include <clocksource/arm_arch_timer.h>
31
32#if IS_ENABLED(CONFIG_FSL_ERRATUM_A008585)
33extern struct static_key_false arch_timer_read_ool_enabled;
34#define needs_fsl_a008585_workaround() \
35 static_branch_unlikely(&arch_timer_read_ool_enabled)
36#else
37#define needs_fsl_a008585_workaround() false
38#endif
39
40u32 __fsl_a008585_read_cntp_tval_el0(void);
41u32 __fsl_a008585_read_cntv_tval_el0(void);
42u64 __fsl_a008585_read_cntvct_el0(void);
43
44/*
45 * The number of retries is an arbitrary value well beyond the highest number
46 * of iterations the loop has been observed to take.
47 */
48#define __fsl_a008585_read_reg(reg) ({ \
49 u64 _old, _new; \
50 int _retries = 200; \
51 \
52 do { \
53 _old = read_sysreg(reg); \
54 _new = read_sysreg(reg); \
55 _retries--; \
56 } while (unlikely(_old != _new) && _retries); \
57 \
58 WARN_ON_ONCE(!_retries); \
59 _new; \
60})
61
62#define arch_timer_reg_read_stable(reg) \
63({ \
64 u64 _val; \
65 if (needs_fsl_a008585_workaround()) \
66 _val = __fsl_a008585_read_##reg(); \
67 else \
68 _val = read_sysreg(reg); \
69 _val; \
70})
71
72/*
73 * These register accessors are marked inline so the compiler can
74 * nicely work out which register we want, and chuck away the rest of
75 * the code.
76 */
77static __always_inline
78void arch_timer_reg_write_cp15(int access, enum arch_timer_reg reg, u32 val)
79{
80 if (access == ARCH_TIMER_PHYS_ACCESS) {
81 switch (reg) {
82 case ARCH_TIMER_REG_CTRL:
83 write_sysreg(val, cntp_ctl_el0);
84 break;
85 case ARCH_TIMER_REG_TVAL:
86 write_sysreg(val, cntp_tval_el0);
87 break;
88 }
89 } else if (access == ARCH_TIMER_VIRT_ACCESS) {
90 switch (reg) {
91 case ARCH_TIMER_REG_CTRL:
92 write_sysreg(val, cntv_ctl_el0);
93 break;
94 case ARCH_TIMER_REG_TVAL:
95 write_sysreg(val, cntv_tval_el0);
96 break;
97 }
98 }
99
100 isb();
101}
102
103static __always_inline
104u32 arch_timer_reg_read_cp15(int access, enum arch_timer_reg reg)
105{
106 if (access == ARCH_TIMER_PHYS_ACCESS) {
107 switch (reg) {
108 case ARCH_TIMER_REG_CTRL:
109 return read_sysreg(cntp_ctl_el0);
110 case ARCH_TIMER_REG_TVAL:
111 return arch_timer_reg_read_stable(cntp_tval_el0);
112 }
113 } else if (access == ARCH_TIMER_VIRT_ACCESS) {
114 switch (reg) {
115 case ARCH_TIMER_REG_CTRL:
116 return read_sysreg(cntv_ctl_el0);
117 case ARCH_TIMER_REG_TVAL:
118 return arch_timer_reg_read_stable(cntv_tval_el0);
119 }
120 }
121
122 BUG();
123}
124
125static inline u32 arch_timer_get_cntfrq(void)
126{
127 return read_sysreg(cntfrq_el0);
128}
129
130static inline u32 arch_timer_get_cntkctl(void)
131{
132 return read_sysreg(cntkctl_el1);
133}
134
135static inline void arch_timer_set_cntkctl(u32 cntkctl)
136{
137 write_sysreg(cntkctl, cntkctl_el1);
138}
139
140static inline u64 arch_counter_get_cntpct(void)
141{
142 /*
143 * AArch64 kernel and user space mandate the use of CNTVCT.
144 */
145 BUG();
146 return 0;
147}
148
149static inline u64 arch_counter_get_cntvct(void)
150{
151 isb();
152 return arch_timer_reg_read_stable(cntvct_el0);
153}
154
155static inline int arch_timer_arch_init(void)
156{
157 return 0;
158}
159
160#endif