mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-16 01:38:22 +00:00
60262cd041
RISC-V privileged architecture v1.10 defines a real-time counter, exposed as a memory-mapped machine-mode register - mtime. mtime must run at constant frequency, and the platform must provide a mechanism for determining the timebase of mtime. The mtime register has a 64-bit precision on all RV32, RV64, and RV128 systems. Different platform may have different implementation of the mtime block hence an API riscv_get_time() is required by this driver for platform codes to hide such implementation details. For example, on some platforms mtime is provided by the CLINT module, while on some other platforms a simple 'rdtime' can be used to get the timer counter. With this timer driver the U-Boot timer functionalities like delay works correctly now. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de> Reviewed-by: Anup Patel <anup@brainfault.org>
56 lines
1.4 KiB
C
56 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0+
|
|
/*
|
|
* Copyright (C) 2018, Bin Meng <bmeng.cn@gmail.com>
|
|
*
|
|
* RISC-V privileged architecture defined generic timer driver
|
|
*
|
|
* This driver relies on RISC-V platform codes to provide the essential API
|
|
* riscv_get_time() which is supposed to return the timer counter as defined
|
|
* by the RISC-V privileged architecture spec.
|
|
*
|
|
* This driver can be used in both M-mode and S-mode U-Boot.
|
|
*/
|
|
|
|
#include <common.h>
|
|
#include <dm.h>
|
|
#include <errno.h>
|
|
#include <timer.h>
|
|
#include <asm/io.h>
|
|
|
|
/**
|
|
* riscv_get_time() - get the timer counter
|
|
*
|
|
* Platform codes should provide this API in order to make this driver function.
|
|
*
|
|
* @time: the 64-bit timer count as defined by the RISC-V privileged
|
|
* architecture spec.
|
|
* @return: 0 on success, -ve on error.
|
|
*/
|
|
extern int riscv_get_time(u64 *time);
|
|
|
|
static int riscv_timer_get_count(struct udevice *dev, u64 *count)
|
|
{
|
|
return riscv_get_time(count);
|
|
}
|
|
|
|
static int riscv_timer_probe(struct udevice *dev)
|
|
{
|
|
struct timer_dev_priv *uc_priv = dev_get_uclass_priv(dev);
|
|
|
|
/* clock frequency was passed from the cpu driver as driver data */
|
|
uc_priv->clock_rate = dev->driver_data;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct timer_ops riscv_timer_ops = {
|
|
.get_count = riscv_timer_get_count,
|
|
};
|
|
|
|
U_BOOT_DRIVER(riscv_timer) = {
|
|
.name = "riscv_timer",
|
|
.id = UCLASS_TIMER,
|
|
.probe = riscv_timer_probe,
|
|
.ops = &riscv_timer_ops,
|
|
.flags = DM_FLAG_PRE_RELOC,
|
|
};
|