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/*
* H8/300 16bit Timer driver
*
* Copyright 2015 Yoshinori Sato <ysato@users.sourcefoge.jp>
*/
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/clocksource.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#define TSTR 0
#define TISRC 6
#define TCR 0
#define TCNT 2
#define bset(b, a) iowrite8(ioread8(a) | (1 << (b)), (a))
#define bclr(b, a) iowrite8(ioread8(a) & ~(1 << (b)), (a))
struct timer16_priv {
struct clocksource cs;
unsigned long total_cycles;
void __iomem *mapbase;
void __iomem *mapcommon;
unsigned short cs_enabled;
unsigned char enb;
unsigned char ovf;
unsigned char ovie;
};
static unsigned long timer16_get_counter(struct timer16_priv *p)
{
unsigned short v1, v2, v3;
unsigned char o1, o2;
o1 = ioread8(p->mapcommon + TISRC) & p->ovf;
/* Make sure the timer value is stable. Stolen from acpi_pm.c */
do {
o2 = o1;
v1 = ioread16be(p->mapbase + TCNT);
v2 = ioread16be(p->mapbase + TCNT);
v3 = ioread16be(p->mapbase + TCNT);
o1 = ioread8(p->mapcommon + TISRC) & p->ovf;
} while (unlikely((o1 != o2) || (v1 > v2 && v1 < v3)
|| (v2 > v3 && v2 < v1) || (v3 > v1 && v3 < v2)));
if (likely(!o1))
return v2;
else
return v2 + 0x10000;
}
static irqreturn_t timer16_interrupt(int irq, void *dev_id)
{
struct timer16_priv *p = (struct timer16_priv *)dev_id;
bclr(p->ovf, p->mapcommon + TISRC);
p->total_cycles += 0x10000;
return IRQ_HANDLED;
}
static inline struct timer16_priv *cs_to_priv(struct clocksource *cs)
{
return container_of(cs, struct timer16_priv, cs);
}
static cycle_t timer16_clocksource_read(struct clocksource *cs)
{
struct timer16_priv *p = cs_to_priv(cs);
unsigned long raw, value;
value = p->total_cycles;
raw = timer16_get_counter(p);
return value + raw;
}
static int timer16_enable(struct clocksource *cs)
{
struct timer16_priv *p = cs_to_priv(cs);
WARN_ON(p->cs_enabled);
p->total_cycles = 0;
iowrite16be(0x0000, p->mapbase + TCNT);
iowrite8(0x83, p->mapbase + TCR);
bset(p->ovie, p->mapcommon + TISRC);
bset(p->enb, p->mapcommon + TSTR);
p->cs_enabled = true;
return 0;
}
static void timer16_disable(struct clocksource *cs)
{
struct timer16_priv *p = cs_to_priv(cs);
WARN_ON(!p->cs_enabled);
bclr(p->ovie, p->mapcommon + TISRC);
bclr(p->enb, p->mapcommon + TSTR);
p->cs_enabled = false;
}
static struct timer16_priv timer16_priv = {
.cs = {
.name = "h8300_16timer",
.rating = 200,
.read = timer16_clocksource_read,
.enable = timer16_enable,
.disable = timer16_disable,
.mask = CLOCKSOURCE_MASK(sizeof(unsigned long) * 8),
.flags = CLOCK_SOURCE_IS_CONTINUOUS,
},
};
#define REG_CH 0
#define REG_COMM 1
static int __init h8300_16timer_init(struct device_node *node)
{
void __iomem *base[2];
int ret, irq;
unsigned int ch;
struct clk *clk;
clk = of_clk_get(node, 0);
if (IS_ERR(clk)) {
pr_err("failed to get clock for clocksource\n");
return PTR_ERR(clk);
}
ret = -ENXIO;
base[REG_CH] = of_iomap(node, 0);
if (!base[REG_CH]) {
pr_err("failed to map registers for clocksource\n");
goto free_clk;
}
base[REG_COMM] = of_iomap(node, 1);
if (!base[REG_COMM]) {
pr_err("failed to map registers for clocksource\n");
goto unmap_ch;
}
ret = -EINVAL;
irq = irq_of_parse_and_map(node, 0);
if (!irq) {
pr_err("failed to get irq for clockevent\n");
goto unmap_comm;
}
of_property_read_u32(node, "renesas,channel", &ch);
timer16_priv.mapbase = base[REG_CH];
timer16_priv.mapcommon = base[REG_COMM];
timer16_priv.enb = ch;
timer16_priv.ovf = ch;
timer16_priv.ovie = 4 + ch;
ret = request_irq(irq, timer16_interrupt,
IRQF_TIMER, timer16_priv.cs.name, &timer16_priv);
if (ret < 0) {
pr_err("failed to request irq %d of clocksource\n", irq);
goto unmap_comm;
}
clocksource_register_hz(&timer16_priv.cs,
clk_get_rate(clk) / 8);
return 0;
unmap_comm:
iounmap(base[REG_COMM]);
unmap_ch:
iounmap(base[REG_CH]);
free_clk:
clk_put(clk);
return ret;
}
CLOCKSOURCE_OF_DECLARE_RET(h8300_16bit, "renesas,16bit-timer",
h8300_16timer_init);
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