mirror of
https://github.com/cirosantilli/linux-kernel-module-cheat.git
synced 2026-01-26 11:41:35 +01:00
60 lines
1.7 KiB
C
60 lines
1.7 KiB
C
#include <stdio.h>
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#include <inttypes.h>
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#include "common_aarch64.h"
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#define CNTV_CTL_ENABLE (1 << 0)
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#define CNTV_CTL_IMASK (1 << 1)
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#define CNTV_CTL_ISTATUS (1 << 2)
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/* Frequency in Hz. ? */
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SYSREG_READ_WRITE(uint64_t, cntfrq_el0)
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/* Current virtual counter value. */
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SYSREG_READ(uint64_t, cntvct_el0)
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/* Compare value. See: cntv_ctl_el0_enable. */
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SYSREG_READ_WRITE(uint64_t, cntv_cval_el0)
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/* On write, set cntv_cval_el0 = (cntvct_el0 + cntv_tval_el0).
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* This means that the next interrupt will happen in cntv_tval_el0 cycles.
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*/
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SYSREG_READ_WRITE(uint64_t, cntv_tval_el0)
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/* Control register. */
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SYSREG_READ_WRITE(uint32_t, cntv_ctl_el0)
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void cntv_ctl_el0_disable(void) {
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sysreg_cntv_ctl_el0_write(sysreg_cntv_ctl_el0_read() & ~CNTV_CTL_ENABLE);
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}
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/* If enabled, when: cntv_ctl > cntv_cval then:
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*
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* * if CNTV_CTL_IMASK is clear, raise an interrupt
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* * set CNTV_CTL_ISTATUS
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*/
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void cntv_ctl_el0_enable(void) {
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sysreg_cntv_ctl_el0_write(sysreg_cntv_ctl_el0_read() | CNTV_CTL_ENABLE);
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}
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int main(void) {
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/* Initial state. */
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printf("cntv_ctl_el0 0x%" PRIx32 "\n", sysreg_cntv_ctl_el0_read());
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printf("cntfrq_el0 0x%" PRIx64 "\n", sysreg_cntfrq_el0_read());
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printf("cntv_cval_el0 0x%" PRIx64 "\n", sysreg_cntv_cval_el0_read());
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/* Get the counter value many times to watch the time pass. */
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printf("cntvct_el0 0x%" PRIx64 "\n", sysreg_cntvct_el0_read());
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printf("cntvct_el0 0x%" PRIx64 "\n", sysreg_cntvct_el0_read());
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printf("cntvct_el0 0x%" PRIx64 "\n", sysreg_cntvct_el0_read());
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#if 0
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/* TODO crashes gem5. */
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puts("cntfrq_el0 = 1");
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sysreg_cntfrq_el0_write(1);
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printf("cntfrq_el0 0x%" PRIx64 "\n", sysreg_cntfrq_el0_read());
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#endif
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return 0;
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}
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