drivers/clocksource/timer-versatile.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  *
0004  * Copyright (C) 2014 ARM Limited
0005  */
0006
0007 #include <linux/clocksource.h>
0008 #include <linux/io.h>
0009 #include <linux/of.h>
0010 #include <linux/of_address.h>
0011 #include <linux/sched_clock.h>
0012
0013 #define SYS_24MHZ 0x05c
0014
0015 static void __iomem *versatile_sys_24mhz;
0016
0017 static u64 notrace versatile_sys_24mhz_read(void)
0018 {
0019     return readl(versatile_sys_24mhz);
0020 }
0021
0022 static int __init versatile_sched_clock_init(struct device_node *node)
0023 {
0024     void __iomem *base = of_iomap(node, 0);
0025
0026     of_node_clear_flag(node, OF_POPULATED);
0027
0028     if (!base)
0029         return -ENXIO;
0030
0031     versatile_sys_24mhz = base + SYS_24MHZ;
0032
0033     sched_clock_register(versatile_sys_24mhz_read, 32, 24000000);
0034
0035     return 0;
0036 }
0037 TIMER_OF_DECLARE(vexpress, "arm,vexpress-sysreg",
0038                versatile_sched_clock_init);
0039 TIMER_OF_DECLARE(versatile, "arm,versatile-sysreg",
0040                versatile_sched_clock_init);