u-boot/arch/riscv/lib/andes_plmt.c
Sean Anderson e86463f8e3 riscv: Rework Andes PLMT as a UCLASS_TIMER driver
This converts the PLMT driver from the riscv-specific timer interface to be
a DM-based UCLASS_TIMER driver.

The clock-frequency/clocks properties are preferred over timebase-frequency
for two reasons. First, properties which affect a device should be located
near its binding in the device tree. Using timebase-frequency only really
makes sense when the cpu itself is the timer device. This is the case when
we read the time from a CSR, but not when there is a separate device.
Second, it lets the device use the clock subsystem which adds flexibility.
If the device is configured for a different clock speed, the timer can
adjust itself.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Rick Chen <rick@andestech.com>
2020-09-30 08:54:45 +08:00

52 lines
1.1 KiB
C

// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (C) 2019, Rick Chen <rick@andestech.com>
* Copyright (C) 2020, Sean Anderson <seanga2@gmail.com>
*
* U-Boot syscon driver for Andes's Platform Level Machine Timer (PLMT).
* The PLMT block holds memory-mapped mtime register
* associated with timer tick.
*/
#include <common.h>
#include <dm.h>
#include <timer.h>
#include <asm/io.h>
#include <linux/err.h>
/* mtime register */
#define MTIME_REG(base) ((ulong)(base))
static int andes_plmt_get_count(struct udevice *dev, u64 *count)
{
*count = readq((void __iomem *)MTIME_REG(dev->priv));
return 0;
}
static const struct timer_ops andes_plmt_ops = {
.get_count = andes_plmt_get_count,
};
static int andes_plmt_probe(struct udevice *dev)
{
dev->priv = dev_read_addr_ptr(dev);
if (!dev->priv)
return -EINVAL;
return timer_timebase_fallback(dev);
}
static const struct udevice_id andes_plmt_ids[] = {
{ .compatible = "riscv,plmt0" },
{ }
};
U_BOOT_DRIVER(andes_plmt) = {
.name = "andes_plmt",
.id = UCLASS_TIMER,
.of_match = andes_plmt_ids,
.ops = &andes_plmt_ops,
.probe = andes_plmt_probe,
.flags = DM_FLAG_PRE_RELOC,
};