linux/drivers/clocksource/moxart_timer.c

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/*
* MOXA ART SoCs timer handling.
*
* Copyright (C) 2013 Jonas Jensen
*
* Jonas Jensen <jonas.jensen@gmail.com>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/irqreturn.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <linux/io.h>
#include <linux/clocksource.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#define TIMER1_BASE 0x00
#define TIMER2_BASE 0x10
#define TIMER3_BASE 0x20
#define REG_COUNT 0x0 /* writable */
#define REG_LOAD 0x4
#define REG_MATCH1 0x8
#define REG_MATCH2 0xC
#define TIMER_CR 0x30
#define TIMER_INTR_STATE 0x34
#define TIMER_INTR_MASK 0x38
/*
* Moxart TIMER_CR flags:
*
* MOXART_CR_*_CLOCK 0: PCLK, 1: EXT1CLK
* MOXART_CR_*_INT overflow interrupt enable bit
*/
#define MOXART_CR_1_ENABLE BIT(0)
#define MOXART_CR_1_CLOCK BIT(1)
#define MOXART_CR_1_INT BIT(2)
#define MOXART_CR_2_ENABLE BIT(3)
#define MOXART_CR_2_CLOCK BIT(4)
#define MOXART_CR_2_INT BIT(5)
#define MOXART_CR_3_ENABLE BIT(6)
#define MOXART_CR_3_CLOCK BIT(7)
#define MOXART_CR_3_INT BIT(8)
#define MOXART_CR_COUNT_UP BIT(9)
#define MOXART_TIMER1_ENABLE (MOXART_CR_2_ENABLE | MOXART_CR_1_ENABLE)
#define MOXART_TIMER1_DISABLE (MOXART_CR_2_ENABLE)
/*
* The ASpeed variant of the IP block has a different layout
* for the control register
*/
#define ASPEED_CR_1_ENABLE BIT(0)
#define ASPEED_CR_1_CLOCK BIT(1)
#define ASPEED_CR_1_INT BIT(2)
#define ASPEED_CR_2_ENABLE BIT(4)
#define ASPEED_CR_2_CLOCK BIT(5)
#define ASPEED_CR_2_INT BIT(6)
#define ASPEED_CR_3_ENABLE BIT(8)
#define ASPEED_CR_3_CLOCK BIT(9)
#define ASPEED_CR_3_INT BIT(10)
#define ASPEED_TIMER1_ENABLE (ASPEED_CR_2_ENABLE | ASPEED_CR_1_ENABLE)
#define ASPEED_TIMER1_DISABLE (ASPEED_CR_2_ENABLE)
struct moxart_timer {
void __iomem *base;
unsigned int t1_disable_val;
unsigned int t1_enable_val;
unsigned int count_per_tick;
struct clock_event_device clkevt;
};
static inline struct moxart_timer *to_moxart(struct clock_event_device *evt)
{
return container_of(evt, struct moxart_timer, clkevt);
}
static inline void moxart_disable(struct clock_event_device *evt)
{
struct moxart_timer *timer = to_moxart(evt);
writel(timer->t1_disable_val, timer->base + TIMER_CR);
}
static inline void moxart_enable(struct clock_event_device *evt)
{
struct moxart_timer *timer = to_moxart(evt);
writel(timer->t1_enable_val, timer->base + TIMER_CR);
}
static int moxart_shutdown(struct clock_event_device *evt)
{
moxart_disable(evt);
return 0;
}
static int moxart_set_oneshot(struct clock_event_device *evt)
{
moxart_disable(evt);
writel(~0, to_moxart(evt)->base + TIMER1_BASE + REG_LOAD);
return 0;
}
static int moxart_set_periodic(struct clock_event_device *evt)
{
struct moxart_timer *timer = to_moxart(evt);
moxart_disable(evt);
writel(timer->count_per_tick, timer->base + TIMER1_BASE + REG_LOAD);
writel(0, timer->base + TIMER1_BASE + REG_MATCH1);
moxart_enable(evt);
return 0;
}
static int moxart_clkevt_next_event(unsigned long cycles,
struct clock_event_device *evt)
{
struct moxart_timer *timer = to_moxart(evt);
u32 u;
moxart_disable(evt);
u = readl(timer->base + TIMER1_BASE + REG_COUNT) - cycles;
writel(u, timer->base + TIMER1_BASE + REG_MATCH1);
moxart_enable(evt);
return 0;
}
static irqreturn_t moxart_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = dev_id;
evt->event_handler(evt);
return IRQ_HANDLED;
}
static int __init moxart_timer_init(struct device_node *node)
{
int ret, irq;
unsigned long pclk;
struct clk *clk;
struct moxart_timer *timer;
timer = kzalloc(sizeof(*timer), GFP_KERNEL);
if (!timer)
return -ENOMEM;
timer->base = of_iomap(node, 0);
if (!timer->base) {
pr_err("%s: of_iomap failed\n", node->full_name);
ret = -ENXIO;
goto out_free;
}
irq = irq_of_parse_and_map(node, 0);
if (irq <= 0) {
pr_err("%s: irq_of_parse_and_map failed\n", node->full_name);
ret = -EINVAL;
goto out_unmap;
}
clk = of_clk_get(node, 0);
if (IS_ERR(clk)) {
pr_err("%s: of_clk_get failed\n", node->full_name);
ret = PTR_ERR(clk);
goto out_unmap;
}
pclk = clk_get_rate(clk);
if (of_device_is_compatible(node, "moxa,moxart-timer")) {
timer->t1_enable_val = MOXART_TIMER1_ENABLE;
timer->t1_disable_val = MOXART_TIMER1_DISABLE;
} else if (of_device_is_compatible(node, "aspeed,ast2400-timer")) {
timer->t1_enable_val = ASPEED_TIMER1_ENABLE;
timer->t1_disable_val = ASPEED_TIMER1_DISABLE;
} else {
pr_err("%s: unknown platform\n", node->full_name);
ret = -EINVAL;
goto out_unmap;
}
timer->count_per_tick = DIV_ROUND_CLOSEST(pclk, HZ);
timer->clkevt.name = node->name;
timer->clkevt.rating = 200;
timer->clkevt.features = CLOCK_EVT_FEAT_PERIODIC |
CLOCK_EVT_FEAT_ONESHOT;
timer->clkevt.set_state_shutdown = moxart_shutdown;
timer->clkevt.set_state_periodic = moxart_set_periodic;
timer->clkevt.set_state_oneshot = moxart_set_oneshot;
timer->clkevt.tick_resume = moxart_set_oneshot;
timer->clkevt.set_next_event = moxart_clkevt_next_event;
timer->clkevt.cpumask = cpumask_of(0);
timer->clkevt.irq = irq;
ret = clocksource_mmio_init(timer->base + TIMER2_BASE + REG_COUNT,
"moxart_timer", pclk, 200, 32,
clocksource_mmio_readl_down);
if (ret) {
pr_err("%s: clocksource_mmio_init failed\n", node->full_name);
goto out_unmap;
}
ret = request_irq(irq, moxart_timer_interrupt, IRQF_TIMER,
node->name, &timer->clkevt);
if (ret) {
pr_err("%s: setup_irq failed\n", node->full_name);
goto out_unmap;
}
/* Clear match registers */
writel(0, timer->base + TIMER1_BASE + REG_MATCH1);
writel(0, timer->base + TIMER1_BASE + REG_MATCH2);
writel(0, timer->base + TIMER2_BASE + REG_MATCH1);
writel(0, timer->base + TIMER2_BASE + REG_MATCH2);
/*
* Start timer 2 rolling as our main wall clock source, keep timer 1
* disabled
*/
writel(0, timer->base + TIMER_CR);
writel(~0, timer->base + TIMER2_BASE + REG_LOAD);
writel(timer->t1_disable_val, timer->base + TIMER_CR);
/*
* documentation is not publicly available:
* min_delta / max_delta obtained by trial-and-error,
* max_delta 0xfffffffe should be ok because count
* register size is u32
*/
clockevents_config_and_register(&timer->clkevt, pclk, 0x4, 0xfffffffe);
return 0;
out_unmap:
iounmap(timer->base);
out_free:
kfree(timer);
return ret;
}
CLOCKSOURCE_OF_DECLARE(moxart, "moxa,moxart-timer", moxart_timer_init);
CLOCKSOURCE_OF_DECLARE(aspeed, "aspeed,ast2400-timer", moxart_timer_init);