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alistair23-linux/arch/arm/mach-imx/time.c
Anson Huang bad3db104f ARM: imx: source gpt per clk from OSC for system timer 
On i.MX6Q TO > 1.0, i.MX6DL and i.MX6SX, gpt per clock
can be from OSC instead of ipg_per, as ipg_per's rate
may be scaled when system enter low bus mode, to keep
system timer NOT drift, better to make gpt per clock
at fixed rate, here add support for gpt per clock to
be from OSC which is at fixed rate always.

There are some difference on this implementation of
gpt per clock source, see below for details:

i.MX6Q TO > 1.0: GPT_CR_CLKSRC, b'101 selects fix clock
    of OSC / 8 for gpt per clk;
i.MX6DL and i.MX6SX: GPT_CR_CLKSRC, b'101 selects OSC
    for gpt per clk, and we must enable GPT_CR_24MEM to
    enable OSC clk source for gpt per, GPT_PR_PRESCALER24M
    is for pre-scaling of this OSC clk, here set it to 8
    to make gpt per clk is 3MHz;
i.MX6SL: ipg_per can be from OSC directly, so no need to
    implement this new clk source for gpt per.

Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
2014-09-16 10:09:41 +08:00

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/*
* linux/arch/arm/plat-mxc/time.c
*
* Copyright (C) 2000-2001 Deep Blue Solutions
* Copyright (C) 2002 Shane Nay (shane@minirl.com)
* Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
* Copyright (C) 2008 Juergen Beisert (kernel@pengutronix.de)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clockchips.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/sched_clock.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
#include <asm/mach/time.h>
#include "common.h"
#include "hardware.h"
/*
* There are 2 versions of the timer hardware on Freescale MXC hardware.
* Version 1: MX1/MXL, MX21, MX27.
* Version 2: MX25, MX31, MX35, MX37, MX51
*/
/* defines common for all i.MX */
#define MXC_TCTL 0x00
#define MXC_TCTL_TEN (1 << 0) /* Enable module */
#define MXC_TPRER 0x04
/* MX1, MX21, MX27 */
#define MX1_2_TCTL_CLK_PCLK1 (1 << 1)
#define MX1_2_TCTL_IRQEN (1 << 4)
#define MX1_2_TCTL_FRR (1 << 8)
#define MX1_2_TCMP 0x08
#define MX1_2_TCN 0x10
#define MX1_2_TSTAT 0x14
/* MX21, MX27 */
#define MX2_TSTAT_CAPT (1 << 1)
#define MX2_TSTAT_COMP (1 << 0)
/* MX31, MX35, MX25, MX5, MX6 */
#define V2_TCTL_WAITEN (1 << 3) /* Wait enable mode */
#define V2_TCTL_CLK_IPG (1 << 6)
#define V2_TCTL_CLK_PER (2 << 6)
#define V2_TCTL_CLK_OSC_DIV8 (5 << 6)
#define V2_TCTL_FRR (1 << 9)
#define V2_TCTL_24MEN (1 << 10)
#define V2_TPRER_PRE24M 12
#define V2_IR 0x0c
#define V2_TSTAT 0x08
#define V2_TSTAT_OF1 (1 << 0)
#define V2_TCN 0x24
#define V2_TCMP 0x10
#define V2_TIMER_RATE_OSC_DIV8 3000000
#define timer_is_v1() (cpu_is_mx1() || cpu_is_mx21() || cpu_is_mx27())
#define timer_is_v2() (!timer_is_v1())
static struct clock_event_device clockevent_mxc;
static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
static void __iomem *timer_base;
static inline void gpt_irq_disable(void)
{
unsigned int tmp;
if (timer_is_v2())
__raw_writel(0, timer_base + V2_IR);
else {
tmp = __raw_readl(timer_base + MXC_TCTL);
__raw_writel(tmp & ~MX1_2_TCTL_IRQEN, timer_base + MXC_TCTL);
}
}
static inline void gpt_irq_enable(void)
{
if (timer_is_v2())
__raw_writel(1<<0, timer_base + V2_IR);
else {
__raw_writel(__raw_readl(timer_base + MXC_TCTL) | MX1_2_TCTL_IRQEN,
timer_base + MXC_TCTL);
}
}
static void gpt_irq_acknowledge(void)
{
if (timer_is_v1()) {
if (cpu_is_mx1())
__raw_writel(0, timer_base + MX1_2_TSTAT);
else
__raw_writel(MX2_TSTAT_CAPT | MX2_TSTAT_COMP,
timer_base + MX1_2_TSTAT);
} else if (timer_is_v2())
__raw_writel(V2_TSTAT_OF1, timer_base + V2_TSTAT);
}
static void __iomem *sched_clock_reg;
static u64 notrace mxc_read_sched_clock(void)
{
return sched_clock_reg ? __raw_readl(sched_clock_reg) : 0;
}
static struct delay_timer imx_delay_timer;
static unsigned long imx_read_current_timer(void)
{
return __raw_readl(sched_clock_reg);
}
static int __init mxc_clocksource_init(struct clk *timer_clk)
{
unsigned int c = clk_get_rate(timer_clk);
void __iomem *reg = timer_base + (timer_is_v2() ? V2_TCN : MX1_2_TCN);
imx_delay_timer.read_current_timer = &imx_read_current_timer;
imx_delay_timer.freq = c;
register_current_timer_delay(&imx_delay_timer);
sched_clock_reg = reg;
sched_clock_register(mxc_read_sched_clock, 32, c);
return clocksource_mmio_init(reg, "mxc_timer1", c, 200, 32,
clocksource_mmio_readl_up);
}
/* clock event */
static int mx1_2_set_next_event(unsigned long evt,
struct clock_event_device *unused)
{
unsigned long tcmp;
tcmp = __raw_readl(timer_base + MX1_2_TCN) + evt;
__raw_writel(tcmp, timer_base + MX1_2_TCMP);
return (int)(tcmp - __raw_readl(timer_base + MX1_2_TCN)) < 0 ?
-ETIME : 0;
}
static int v2_set_next_event(unsigned long evt,
struct clock_event_device *unused)
{
unsigned long tcmp;
tcmp = __raw_readl(timer_base + V2_TCN) + evt;
__raw_writel(tcmp, timer_base + V2_TCMP);
return evt < 0x7fffffff &&
(int)(tcmp - __raw_readl(timer_base + V2_TCN)) < 0 ?
-ETIME : 0;
}
#ifdef DEBUG
static const char *clock_event_mode_label[] = {
[CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
[CLOCK_EVT_MODE_ONESHOT] = "CLOCK_EVT_MODE_ONESHOT",
[CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
[CLOCK_EVT_MODE_UNUSED] = "CLOCK_EVT_MODE_UNUSED",
[CLOCK_EVT_MODE_RESUME] = "CLOCK_EVT_MODE_RESUME",
};
#endif /* DEBUG */
static void mxc_set_mode(enum clock_event_mode mode,
struct clock_event_device *evt)
{
unsigned long flags;
/*
* The timer interrupt generation is disabled at least
* for enough time to call mxc_set_next_event()
*/
local_irq_save(flags);
/* Disable interrupt in GPT module */
gpt_irq_disable();
if (mode != clockevent_mode) {
/* Set event time into far-far future */
if (timer_is_v2())
__raw_writel(__raw_readl(timer_base + V2_TCN) - 3,
timer_base + V2_TCMP);
else
__raw_writel(__raw_readl(timer_base + MX1_2_TCN) - 3,
timer_base + MX1_2_TCMP);
/* Clear pending interrupt */
gpt_irq_acknowledge();
}
#ifdef DEBUG
printk(KERN_INFO "mxc_set_mode: changing mode from %s to %s\n",
clock_event_mode_label[clockevent_mode],
clock_event_mode_label[mode]);
#endif /* DEBUG */
/* Remember timer mode */
clockevent_mode = mode;
local_irq_restore(flags);
switch (mode) {
case CLOCK_EVT_MODE_PERIODIC:
printk(KERN_ERR"mxc_set_mode: Periodic mode is not "
"supported for i.MX\n");
break;
case CLOCK_EVT_MODE_ONESHOT:
/*
* Do not put overhead of interrupt enable/disable into
* mxc_set_next_event(), the core has about 4 minutes
* to call mxc_set_next_event() or shutdown clock after
* mode switching
*/
local_irq_save(flags);
gpt_irq_enable();
local_irq_restore(flags);
break;
case CLOCK_EVT_MODE_SHUTDOWN:
case CLOCK_EVT_MODE_UNUSED:
case CLOCK_EVT_MODE_RESUME:
/* Left event sources disabled, no more interrupts appear */
break;
}
}
/*
* IRQ handler for the timer
*/
static irqreturn_t mxc_timer_interrupt(int irq, void *dev_id)
{
struct clock_event_device *evt = &clockevent_mxc;
uint32_t tstat;
if (timer_is_v2())
tstat = __raw_readl(timer_base + V2_TSTAT);
else
tstat = __raw_readl(timer_base + MX1_2_TSTAT);
gpt_irq_acknowledge();
evt->event_handler(evt);
return IRQ_HANDLED;
}
static struct irqaction mxc_timer_irq = {
.name = "i.MX Timer Tick",
.flags = IRQF_TIMER | IRQF_IRQPOLL,
.handler = mxc_timer_interrupt,
};
static struct clock_event_device clockevent_mxc = {
.name = "mxc_timer1",
.features = CLOCK_EVT_FEAT_ONESHOT,
.set_mode = mxc_set_mode,
.set_next_event = mx1_2_set_next_event,
.rating = 200,
};
static int __init mxc_clockevent_init(struct clk *timer_clk)
{
if (timer_is_v2())
clockevent_mxc.set_next_event = v2_set_next_event;
clockevent_mxc.cpumask = cpumask_of(0);
clockevents_config_and_register(&clockevent_mxc,
clk_get_rate(timer_clk),
0xff, 0xfffffffe);
return 0;
}
static void __init _mxc_timer_init(int irq,
struct clk *clk_per, struct clk *clk_ipg)
{
uint32_t tctl_val;
if (IS_ERR(clk_per)) {
pr_err("i.MX timer: unable to get clk\n");
return;
}
if (!IS_ERR(clk_ipg))
clk_prepare_enable(clk_ipg);
clk_prepare_enable(clk_per);
/*
* Initialise to a known state (all timers off, and timing reset)
*/
__raw_writel(0, timer_base + MXC_TCTL);
__raw_writel(0, timer_base + MXC_TPRER); /* see datasheet note */
if (timer_is_v2()) {
tctl_val = V2_TCTL_FRR | V2_TCTL_WAITEN | MXC_TCTL_TEN;
if (clk_get_rate(clk_per) == V2_TIMER_RATE_OSC_DIV8) {
tctl_val |= V2_TCTL_CLK_OSC_DIV8;
if (cpu_is_imx6dl() || cpu_is_imx6sx()) {
/* 24 / 8 = 3 MHz */
__raw_writel(7 << V2_TPRER_PRE24M,
timer_base + MXC_TPRER);
tctl_val |= V2_TCTL_24MEN;
}
} else {
tctl_val |= V2_TCTL_CLK_PER;
}
} else {
tctl_val = MX1_2_TCTL_FRR | MX1_2_TCTL_CLK_PCLK1 | MXC_TCTL_TEN;
}
__raw_writel(tctl_val, timer_base + MXC_TCTL);
/* init and register the timer to the framework */
mxc_clocksource_init(clk_per);
mxc_clockevent_init(clk_per);
/* Make irqs happen */
setup_irq(irq, &mxc_timer_irq);
}
void __init mxc_timer_init(void __iomem *base, int irq)
{
struct clk *clk_per = clk_get_sys("imx-gpt.0", "per");
struct clk *clk_ipg = clk_get_sys("imx-gpt.0", "ipg");
timer_base = base;
_mxc_timer_init(irq, clk_per, clk_ipg);
}
static void __init mxc_timer_init_dt(struct device_node *np)
{
struct clk *clk_per, *clk_ipg;
int irq;
if (timer_base)
return;
timer_base = of_iomap(np, 0);
WARN_ON(!timer_base);
irq = irq_of_parse_and_map(np, 0);
clk_ipg = of_clk_get_by_name(np, "ipg");
/* Try osc_per first, and fall back to per otherwise */
clk_per = of_clk_get_by_name(np, "osc_per");
if (IS_ERR(clk_per))
clk_per = of_clk_get_by_name(np, "per");
_mxc_timer_init(irq, clk_per, clk_ipg);
}
CLOCKSOURCE_OF_DECLARE(mx1_timer, "fsl,imx1-gpt", mxc_timer_init_dt);
CLOCKSOURCE_OF_DECLARE(mx25_timer, "fsl,imx25-gpt", mxc_timer_init_dt);
CLOCKSOURCE_OF_DECLARE(mx50_timer, "fsl,imx50-gpt", mxc_timer_init_dt);
CLOCKSOURCE_OF_DECLARE(mx51_timer, "fsl,imx51-gpt", mxc_timer_init_dt);
CLOCKSOURCE_OF_DECLARE(mx53_timer, "fsl,imx53-gpt", mxc_timer_init_dt);
CLOCKSOURCE_OF_DECLARE(mx6q_timer, "fsl,imx6q-gpt", mxc_timer_init_dt);
CLOCKSOURCE_OF_DECLARE(mx6sl_timer, "fsl,imx6sl-gpt", mxc_timer_init_dt);
CLOCKSOURCE_OF_DECLARE(mx6sx_timer, "fsl,imx6sx-gpt", mxc_timer_init_dt);
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