linux/drivers/clocksource/timer-msc313e.c
Romain Perier e64da64f41 clocksource/drivers/msc313e: Add support for ssd20xd-based platforms
On SSD20X family SoCs the timers are connected to a 432MHz clock instead
of 12MHz that all the previous chips used. There is no way to reduce or
divide these clocks in the clktree yet as we do not know exactly where
the 432MHz clock comes from but it is enabled at boot.

The SSD20X timers have an input clock divider within the timer itself
to configure the frequency. timer0 is preconfigured at power up to run
at 12MHz so it is backwards compatible and doesn't need special handling
right now. timer1 and timer2 run at 432Mhz at power up so are not
backward compatible.

This commit adds support for the input clock divider register and sets
timer1 and timer2 to run at 48Mhz for clockevents.

Signed-off-by: Romain Perier <romain.perier@gmail.com>
Link: https://lore.kernel.org/r/20211217195727.8955-3-romain.perier@gmail.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
2021-12-20 13:28:39 +01:00

254 lines
6.0 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* MStar timer driver
*
* Copyright (C) 2021 Daniel Palmer
* Copyright (C) 2021 Romain Perier
*
*/
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqreturn.h>
#include <linux/sched_clock.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#ifdef CONFIG_ARM
#include <linux/delay.h>
#endif
#include "timer-of.h"
#define TIMER_NAME "msc313e_timer"
#define MSC313E_REG_CTRL 0x00
#define MSC313E_REG_CTRL_TIMER_EN BIT(0)
#define MSC313E_REG_CTRL_TIMER_TRIG BIT(1)
#define MSC313E_REG_CTRL_TIMER_INT_EN BIT(8)
#define MSC313E_REG_TIMER_MAX_LOW 0x08
#define MSC313E_REG_TIMER_MAX_HIGH 0x0c
#define MSC313E_REG_COUNTER_LOW 0x10
#define MSC313E_REG_COUNTER_HIGH 0x14
#define MSC313E_REG_TIMER_DIVIDE 0x18
#define MSC313E_CLK_DIVIDER 9
#define TIMER_SYNC_TICKS 3
#ifdef CONFIG_ARM
struct msc313e_delay {
void __iomem *base;
struct delay_timer delay;
};
static struct msc313e_delay msc313e_delay;
#endif
static void __iomem *msc313e_clksrc;
static void msc313e_timer_stop(void __iomem *base)
{
writew(0, base + MSC313E_REG_CTRL);
}
static void msc313e_timer_start(void __iomem *base, bool periodic)
{
u16 reg;
reg = readw(base + MSC313E_REG_CTRL);
if (periodic)
reg |= MSC313E_REG_CTRL_TIMER_EN;
else
reg |= MSC313E_REG_CTRL_TIMER_TRIG;
writew(reg | MSC313E_REG_CTRL_TIMER_INT_EN, base + MSC313E_REG_CTRL);
}
static void msc313e_timer_setup(void __iomem *base, unsigned long delay)
{
unsigned long flags;
local_irq_save(flags);
writew(delay >> 16, base + MSC313E_REG_TIMER_MAX_HIGH);
writew(delay & 0xffff, base + MSC313E_REG_TIMER_MAX_LOW);
local_irq_restore(flags);
}
static unsigned long msc313e_timer_current_value(void __iomem *base)
{
unsigned long flags;
u16 l, h;
local_irq_save(flags);
l = readw(base + MSC313E_REG_COUNTER_LOW);
h = readw(base + MSC313E_REG_COUNTER_HIGH);
local_irq_restore(flags);
return (((u32)h) << 16 | l);
}
static int msc313e_timer_clkevt_shutdown(struct clock_event_device *evt)
{
struct timer_of *timer = to_timer_of(evt);
msc313e_timer_stop(timer_of_base(timer));
return 0;
}
static int msc313e_timer_clkevt_set_oneshot(struct clock_event_device *evt)
{
struct timer_of *timer = to_timer_of(evt);
msc313e_timer_stop(timer_of_base(timer));
msc313e_timer_start(timer_of_base(timer), false);
return 0;
}
static int msc313e_timer_clkevt_set_periodic(struct clock_event_device *evt)
{
struct timer_of *timer = to_timer_of(evt);
msc313e_timer_stop(timer_of_base(timer));
msc313e_timer_setup(timer_of_base(timer), timer_of_period(timer));
msc313e_timer_start(timer_of_base(timer), true);
return 0;
}
static int msc313e_timer_clkevt_next_event(unsigned long evt, struct clock_event_device *clkevt)
{
struct timer_of *timer = to_timer_of(clkevt);
msc313e_timer_stop(timer_of_base(timer));
msc313e_timer_setup(timer_of_base(timer), evt);
msc313e_timer_start(timer_of_base(timer), false);
return 0;
}
static irqreturn_t msc313e_timer_clkevt_irq(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
evt->event_handler(evt);
return IRQ_HANDLED;
}
static u64 msc313e_timer_clksrc_read(struct clocksource *cs)
{
return msc313e_timer_current_value(msc313e_clksrc) & cs->mask;
}
#ifdef CONFIG_ARM
static unsigned long msc313e_read_delay_timer_read(void)
{
return msc313e_timer_current_value(msc313e_delay.base);
}
#endif
static u64 msc313e_timer_sched_clock_read(void)
{
return msc313e_timer_current_value(msc313e_clksrc);
}
static struct clock_event_device msc313e_clkevt = {
.name = TIMER_NAME,
.rating = 300,
.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
.set_state_shutdown = msc313e_timer_clkevt_shutdown,
.set_state_periodic = msc313e_timer_clkevt_set_periodic,
.set_state_oneshot = msc313e_timer_clkevt_set_oneshot,
.tick_resume = msc313e_timer_clkevt_shutdown,
.set_next_event = msc313e_timer_clkevt_next_event,
};
static int __init msc313e_clkevt_init(struct device_node *np)
{
int ret;
struct timer_of *to;
to = kzalloc(sizeof(*to), GFP_KERNEL);
if (!to)
return -ENOMEM;
to->flags = TIMER_OF_IRQ | TIMER_OF_CLOCK | TIMER_OF_BASE;
to->of_irq.handler = msc313e_timer_clkevt_irq;
ret = timer_of_init(np, to);
if (ret)
return ret;
if (of_device_is_compatible(np, "sstar,ssd20xd-timer")) {
to->of_clk.rate = clk_get_rate(to->of_clk.clk) / MSC313E_CLK_DIVIDER;
to->of_clk.period = DIV_ROUND_UP(to->of_clk.rate, HZ);
writew(MSC313E_CLK_DIVIDER - 1, timer_of_base(to) + MSC313E_REG_TIMER_DIVIDE);
}
msc313e_clkevt.cpumask = cpu_possible_mask;
msc313e_clkevt.irq = to->of_irq.irq;
to->clkevt = msc313e_clkevt;
clockevents_config_and_register(&to->clkevt, timer_of_rate(to),
TIMER_SYNC_TICKS, 0xffffffff);
return 0;
}
static int __init msc313e_clksrc_init(struct device_node *np)
{
struct timer_of to = { 0 };
int ret;
u16 reg;
to.flags = TIMER_OF_BASE | TIMER_OF_CLOCK;
ret = timer_of_init(np, &to);
if (ret)
return ret;
msc313e_clksrc = timer_of_base(&to);
reg = readw(msc313e_clksrc + MSC313E_REG_CTRL);
reg |= MSC313E_REG_CTRL_TIMER_EN;
writew(reg, msc313e_clksrc + MSC313E_REG_CTRL);
#ifdef CONFIG_ARM
msc313e_delay.base = timer_of_base(&to);
msc313e_delay.delay.read_current_timer = msc313e_read_delay_timer_read;
msc313e_delay.delay.freq = timer_of_rate(&to);
register_current_timer_delay(&msc313e_delay.delay);
#endif
sched_clock_register(msc313e_timer_sched_clock_read, 32, timer_of_rate(&to));
return clocksource_mmio_init(timer_of_base(&to), TIMER_NAME, timer_of_rate(&to), 300, 32,
msc313e_timer_clksrc_read);
}
static int __init msc313e_timer_init(struct device_node *np)
{
int ret = 0;
static int num_called;
switch (num_called) {
case 0:
ret = msc313e_clksrc_init(np);
if (ret)
return ret;
break;
default:
ret = msc313e_clkevt_init(np);
if (ret)
return ret;
break;
}
num_called++;
return 0;
}
TIMER_OF_DECLARE(msc313, "mstar,msc313e-timer", msc313e_timer_init);
TIMER_OF_DECLARE(ssd20xd, "sstar,ssd20xd-timer", msc313e_timer_init);