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/*
* Pistachio clocksource based on general-purpose timers
*
* Copyright (C) 2015 Imagination Technologies
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#define pr_fmt(fmt) "%s: " fmt, __func__
#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/mfd/syscon.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/sched_clock.h>
#include <linux/time.h>
/* Top level reg */
#define CR_TIMER_CTRL_CFG 0x00
#define TIMER_ME_GLOBAL BIT(0)
#define CR_TIMER_REV 0x10
/* Timer specific registers */
#define TIMER_CFG 0x20
#define TIMER_ME_LOCAL BIT(0)
#define TIMER_RELOAD_VALUE 0x24
#define TIMER_CURRENT_VALUE 0x28
#define TIMER_CURRENT_OVERFLOW_VALUE 0x2C
#define TIMER_IRQ_STATUS 0x30
#define TIMER_IRQ_CLEAR 0x34
#define TIMER_IRQ_MASK 0x38
#define PERIP_TIMER_CONTROL 0x90
/* Timer specific configuration Values */
#define RELOAD_VALUE 0xffffffff
struct pistachio_clocksource {
void __iomem *base;
raw_spinlock_t lock;
struct clocksource cs;
};
static struct pistachio_clocksource pcs_gpt;
#define to_pistachio_clocksource(cs) \
container_of(cs, struct pistachio_clocksource, cs)
static inline u32 gpt_readl(void __iomem *base, u32 offset, u32 gpt_id)
{
return readl(base + 0x20 * gpt_id + offset);
}
static inline void gpt_writel(void __iomem *base, u32 value, u32 offset,
u32 gpt_id)
{
writel(value, base + 0x20 * gpt_id + offset);
}
static u64 notrace
pistachio_clocksource_read_cycles(struct clocksource *cs)
{
struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
u32 counter, overflow;
unsigned long flags;
/*
* The counter value is only refreshed after the overflow value is read.
* And they must be read in strict order, hence raw spin lock added.
*/
raw_spin_lock_irqsave(&pcs->lock, flags);
overflow = gpt_readl(pcs->base, TIMER_CURRENT_OVERFLOW_VALUE, 0);
counter = gpt_readl(pcs->base, TIMER_CURRENT_VALUE, 0);
raw_spin_unlock_irqrestore(&pcs->lock, flags);
return (u64)~counter;
}
static u64 notrace pistachio_read_sched_clock(void)
{
return pistachio_clocksource_read_cycles(&pcs_gpt.cs);
}
static void pistachio_clksrc_set_mode(struct clocksource *cs, int timeridx,
int enable)
{
struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
u32 val;
val = gpt_readl(pcs->base, TIMER_CFG, timeridx);
if (enable)
val |= TIMER_ME_LOCAL;
else
val &= ~TIMER_ME_LOCAL;
gpt_writel(pcs->base, val, TIMER_CFG, timeridx);
}
static void pistachio_clksrc_enable(struct clocksource *cs, int timeridx)
{
struct pistachio_clocksource *pcs = to_pistachio_clocksource(cs);
/* Disable GPT local before loading reload value */
pistachio_clksrc_set_mode(cs, timeridx, false);
gpt_writel(pcs->base, RELOAD_VALUE, TIMER_RELOAD_VALUE, timeridx);
pistachio_clksrc_set_mode(cs, timeridx, true);
}
static void pistachio_clksrc_disable(struct clocksource *cs, int timeridx)
{
/* Disable GPT local */
pistachio_clksrc_set_mode(cs, timeridx, false);
}
static int pistachio_clocksource_enable(struct clocksource *cs)
{
pistachio_clksrc_enable(cs, 0);
return 0;
}
static void pistachio_clocksource_disable(struct clocksource *cs)
{
pistachio_clksrc_disable(cs, 0);
}
/* Desirable clock source for pistachio platform */
static struct pistachio_clocksource pcs_gpt = {
.cs = {
.name = "gptimer",
.rating = 300,
.enable = pistachio_clocksource_enable,
.disable = pistachio_clocksource_disable,
.read = pistachio_clocksource_read_cycles,
.mask = CLOCKSOURCE_MASK(32),
.flags = CLOCK_SOURCE_IS_CONTINUOUS |
CLOCK_SOURCE_SUSPEND_NONSTOP,
},
};
static int __init pistachio_clksrc_of_init(struct device_node *node)
{
struct clk *sys_clk, *fast_clk;
struct regmap *periph_regs;
unsigned long rate;
int ret;
pcs_gpt.base = of_iomap(node, 0);
if (!pcs_gpt.base) {
pr_err("cannot iomap\n");
return -ENXIO;
}
periph_regs = syscon_regmap_lookup_by_phandle(node, "img,cr-periph");
if (IS_ERR(periph_regs)) {
pr_err("cannot get peripheral regmap (%ld)\n",
PTR_ERR(periph_regs));
return PTR_ERR(periph_regs);
}
/* Switch to using the fast counter clock */
ret = regmap_update_bits(periph_regs, PERIP_TIMER_CONTROL,
0xf, 0x0);
if (ret)
return ret;
sys_clk = of_clk_get_by_name(node, "sys");
if (IS_ERR(sys_clk)) {
pr_err("clock get failed (%ld)\n", PTR_ERR(sys_clk));
return PTR_ERR(sys_clk);
}
fast_clk = of_clk_get_by_name(node, "fast");
if (IS_ERR(fast_clk)) {
pr_err("clock get failed (%lu)\n", PTR_ERR(fast_clk));
return PTR_ERR(fast_clk);
}
ret = clk_prepare_enable(sys_clk);
if (ret < 0) {
pr_err("failed to enable clock (%d)\n", ret);
return ret;
}
ret = clk_prepare_enable(fast_clk);
if (ret < 0) {
pr_err("failed to enable clock (%d)\n", ret);
clk_disable_unprepare(sys_clk);
return ret;
}
rate = clk_get_rate(fast_clk);
/* Disable irq's for clocksource usage */
gpt_writel(pcs_gpt.base, 0, TIMER_IRQ_MASK, 0);
gpt_writel(pcs_gpt.base, 0, TIMER_IRQ_MASK, 1);
gpt_writel(pcs_gpt.base, 0, TIMER_IRQ_MASK, 2);
gpt_writel(pcs_gpt.base, 0, TIMER_IRQ_MASK, 3);
/* Enable timer block */
writel(TIMER_ME_GLOBAL, pcs_gpt.base);
raw_spin_lock_init(&pcs_gpt.lock);
sched_clock_register(pistachio_read_sched_clock, 32, rate);
return clocksource_register_hz(&pcs_gpt.cs, rate);
}
TIMER_OF_DECLARE(pistachio_gptimer, "img,pistachio-gptimer",
pistachio_clksrc_of_init);
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